JP7217558B2 - Projection lens and projection device - Google Patents

Description

The present invention relates to a projection lens and a projection device for projecting light from a light source into a rectangular range.

2. Description of the Related Art Projection systems used in object detection devices, distance measurement devices, backlights of display devices, and the like are known to project light from a light source over a wide range using a projection lens. In Patent Document 1, in order to secure the light intensity within the projection range while making the projection range oval, the emission surface is formed into a complicated three-dimensional shape, and the projection range by the emission surface is disclosed. A projection lens is described in which the incident surface is hemispherical so as not to affect the formation of .

Japanese Patent No. 6460878

However, in the technique described in Patent Document 1, the projection range of the light that has passed through the projection lens is an ellipse. When the range is included inside the oval projection range, the amount of light projected outside the detection range tends to increase. As a result, the light intensity within the detection range is relatively reduced, and the problem arises that the detection sensitivity of the object detection device is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a projection lens and a projection device capable of securing the light intensity within the projection range while making the projection range closer to a rectangular shape. With the goal.

In order to achieve this object, the projection lens of the present invention comprises an incident surface on which light emitted from a light source is incident, and a surface on the opposite side of the incident surface from which the light passes through the incident surface. and an exit surface that emits light to the side, where the optical axis intersecting the entrance surface and the exit surface is the Z axis, and the axes orthogonal to the Z axis and perpendicular to each other are the X axis and the Y axis. The surface and the exit surface are formed line-symmetrically with respect to the Z axis in the XZ cross section and the YZ cross section, respectively. The output surface in the YZ cross section is a concave curve toward the light projection side, and the absolute value of the curvature of the incident surface at the intersection of the Z axis and the incident surface in the XZ cross section is the Z axis and the exit surface, and in the YZ cross section, the absolute value of the curvature of the entrance surface at the intersection of the Z axis and the exit surface is equal to the Z axis and the exit surface is smaller than the absolute value of the curvature of the exit surface at the intersection of .

According to the projection lens of claim 1, in the XZ cross section, the incident surface is a concave curve toward the light source side, and the absolute value of the curvature of the incident surface at the intersection of the Z axis and the incident surface is the Z axis and the exit surface. Since it is larger than the absolute value of the curvature of the exit surface at the intersection with the surface, the light from the light source can be spread mainly in the X-axis direction by the entrance surface. In addition, in the YZ cross section, the exit surface is a concave curve toward the light projection side, and the absolute value of the curvature of the entrance surface at the intersection of the Z axis and the entrance surface is the curvature of the exit surface at the intersection of the Z axis and the exit surface. is smaller than the absolute value of , the light can be spread mainly in the Y-axis direction by the exit surface. In this way, the light from the light source is spread mainly in the X-axis direction by the entrance surface and then spread mainly in the Y-axis direction by the exit surface. can get closer.

Furthermore, since the absolute value of the curvature of the incident surface in the XZ cross section becomes smaller as the distance from the Z axis increases, the incident surface diffuses the ray bundle greatly in the vicinity of the Z axis, while at the peripheral part away from the Z axis in the X axis direction. It can spread small. As a result, the light intensity of the light reaching the exit surface can be reduced in the vicinity of the Z-axis and increased in the peripheral portion away from the Z-axis in the X-axis direction. By aligning the portion of the light emitted from the light source where the light intensity is high with the Z-axis, the light intensity of the light reaching the exit surface through the entrance surface can be ensured over substantially the entire length in the X-axis direction. Since the ray bundle with such light intensity is spread mainly in the Y-axis direction by the exit surface, the light intensity of the light that has passed through the projection lens can be ensured over substantially the entire projection range.

According to the projection lens of claim 2, in addition to the effects of the projection lens of claim 1, the following effects are achieved. Since the absolute value of the curvature of the XZ cross section at the intersection of the Z axis and the incident surface is larger than the absolute value of the curvature of the YZ cross section at the intersection of the Z axis and the incident surface, the incident surface directs the light to the Y axis. It can diffuse small in the direction and large in the X-axis direction. In addition, since the absolute value of the curvature of the YZ section at the intersection of the Z axis and the emission surface is larger than the absolute value of the curvature of the XZ section at the intersection of the Z axis and the emission surface, the light is emitted by the emission surface. It can diffuse small in the X-axis direction and large in the Y-axis direction. As a result, the role of expanding the light from the light source in the X-axis direction and the role of expanding the light in the Y-axis direction can be easily divided between the entrance surface and the exit surface, respectively. can be made closer to a rectangular shape, and the light intensity within the projection range can be easily ensured.

According to the projection lens of claim 3, in addition to the effects of the projection lens of claim 1 or 2, the following effects are achieved. The entrance surface and the exit surface are anamorphic surfaces formed symmetrically with respect to the XZ cross section and the YZ cross section, respectively. As a result, it is possible to easily individually set how the light spreads in the X-axis direction and how the light spreads in the Y-axis direction on the incident surface, and how the light spreads in the X-axis direction and the Y-axis direction on the exit surface. How to spread light in the axial direction can be easily set individually. As a result, it is possible to easily design a light projecting lens for securing the light intensity within the light projection range while making the light projection range closer to a rectangular shape.

According to the projection lens of claim 4, in addition to the effects of the projection lens of claim 3, the following effects are achieved. One of the incident surface and the exit surface is a cylindrical surface having a linear cross section perpendicular to either the X-axis direction or the Y-axis direction. The other of the incident surface and the exit surface is a toroidal surface having curved cross sections perpendicular to both the X-axis direction and the Y-axis direction. The cylindrical surface, which is easier to form than the toroidal surface and has a small error sensitivity, can easily diffuse light in one direction, and the toroidal surface facilitates diffusion of light in the other direction while diffusing light in one direction. can be adjusted. As a result, the projection range of the light that has passed through the projection lens can be easily adjusted in a rectangular shape, and the light intensity within the projection range can be easily ensured.

According to the projection lens of claim 5, in addition to the effects of the projection lens of any one of claims 1 to 4, the following effects are achieved. The exit surface in the XZ cross section is formed by a curved line that is concave in the vicinity of the Z axis and becomes convex at a position away from the Z axis. As a result, the ray bundle emitted from the exit surface can be greatly diffused in the vicinity of the Z-axis while being slightly diffused in the peripheral portion away from the Z-axis in the X-axis direction. can be increased at the periphery.

According to the projection lens of claim 6, in addition to the effects of the projection lens of any one of claims 1 to 5, the following effects are achieved. The exit surface in the YZ cross section is a concave curve whose absolute value of curvature decreases with increasing distance from the Z axis. As a result, the ray bundle emitted from the exit surface can be greatly diffused in the vicinity of the Z-axis while being slightly diffused in the peripheral portion away from the Z-axis in the Y-axis direction. can be increased at the periphery.

According to the projection lens of claim 7, in addition to the effects of the projection lens of any one of claims 1 to 6, the following effects are achieved. In the XZ cross section, rays emitted from the light source include inner rays whose divergence angle is in the range of more than 0° and less than or equal to the half-value half-angle. In the XZ cross section, the ray that the inner ray is incident on the incident surface and refracted is defined as the first X refracted ray, and the line obtained by extending the inner ray is defined as the first X extension line. Further, a ray that is refracted after entering the exit surface of the first X refracted ray is referred to as a second X refracted ray, and a line obtained by extending the first X refracted ray is referred to as a second X extension line. When the light source is placed at a position where the angle of incidence of the inner ray on the incident surface increases as the incident position of the inner ray on the incident surface moves away from the Z axis, a shape that satisfies the following two conditions is obtained in the XZ cross section. An entrance surface and an exit surface are set.

The first condition is that the first X refracted ray lies on the side of the first X extension line opposite the Z axis, and the second X refracted ray lies on the side of the second X extension line opposite the Z axis. That is. The second condition is that as the incident position of the inner ray on the incident surface moves away from the Z axis, the 1st X deviation angle between the 1X refracted ray and the 1st X extension line increases, and the 1X The second X deflection angle between the second X refracted ray and the second X extension line increases as the incident position of the refracted ray moves away from the Z axis. By satisfying these conditions, the inner ray can be diffused over a wide range in the X-axis direction, and the angle of view of the projection lens can be widened in the X-axis direction.

According to the projection lens of claim 8, in addition to the effects of the projection lens of any one of claims 1 to 7, the following effects are achieved. In the YZ cross section, a ray that travels from the incident surface to the exit surface is the first Y refracted ray, a ray that is incident on the exit surface and refracted by the first Y refracted ray is the second Y refracted ray, and a line obtained by extending the first Y refracted ray is the second Y refracted ray. 2Y extension line. In the YZ cross section, the second Y refracted ray is located on the side opposite to the Z axis with respect to the second Y extension line, and the second Y refracted ray and The shape of the output surface is set so that the second Y deflection angle with respect to the second Y extension line is large. As a result, the light can be diffused over a wide range in the Y-axis direction by the exit surface, so that the angle of view of the projection lens can be widened in the Y-axis direction.

According to the projection lens of claim 9, in addition to the effects of the projection lens of any one of claims 1 to 8, the following effects are achieved. The projection lens is made of a material having a refractive index of 1.56 or more at the wavelength of light emitted from the light source. This makes it possible to widen the angle of view while reducing the size of the projection lens.

According to claim 10, there is provided a projection device comprising a light source for emitting light in the Z-axis direction and the projection lens according to any one of claims 1 to 9. In addition to the effects of any one of the projection lenses, the following effects are obtained. The light emitted from the light source has light intensity distributions in the XZ cross section and the YZ cross section that are symmetrical with respect to the Z axis, and the light intensity decreases as the distance from the Z axis increases. is also big. This light is spread by the plane of incidence mainly in the X-axis direction so that the light intensity decreases near the Z-axis by the plane of incidence and increases in the periphery away from the Z-axis in the X-axis direction, and then spreads on the plane of exit. is expanded in the Y-axis direction by . As a result, the light projecting device can secure the light intensity over substantially the entire light projection range while making the light projection range closer to a rectangular shape.

1 is a perspective view of a light projecting device according to a first embodiment; FIG. (a) is an XZ sectional view of the projection lens, and (b) is a YZ sectional view of the projection lens. 4 is a light intensity distribution diagram of light emitted from a light source; FIG. (a) is a diagram showing the relationship between the incident angle, the refraction angle, and the deflection angle on the incident surface of the XZ cross section and the divergence angle of the light beam from the light source; FIG. 10C is a relational diagram between angles and divergence angles of light rays from a light source, and FIG. 1C is a relational diagram between incident angles, refraction angles, deviation angles, and divergence angles of light rays from the light source on the exit surface of the YZ cross section. (a) is a diagram showing a light projection range by a light projecting device, (b) is a light intensity distribution diagram in the X-axis direction, and (c) is a light intensity distribution diagram in the Y-axis direction. (a) is an XZ sectional view of the projection lens in the second embodiment, and (b) is a YZ sectional view of the projection lens. (a) is a diagram showing a light projection range by a light projecting device, (b) is a light intensity distribution diagram in the X-axis direction, and (c) is a light intensity distribution diagram in the Y-axis direction. (a) is an XZ sectional view of the projection lens in the third embodiment, and (b) is a YZ sectional view of the projection lens. (a) is a diagram showing a light projection range by a light projecting device, (b) is a light intensity distribution diagram in the X-axis direction, and (c) is a light intensity distribution diagram in the Y-axis direction. (a) is an XZ sectional view of the projection lens in the fourth embodiment, and (b) is a YZ sectional view of the projection lens. (a) is a diagram showing a light projection range by a light projecting device, (b) is a light intensity distribution diagram in the X-axis direction, and (c) is a light intensity distribution diagram in the Y-axis direction. (a) is an XZ sectional view of the projection lens in the fifth embodiment, and (b) is a YZ sectional view of the projection lens. (a) is a diagram showing a light projection range by a light projecting device, (b) is a light intensity distribution diagram in the X-axis direction, and (c) is a light intensity distribution diagram in the Y-axis direction.

Preferred embodiments will now be described with reference to the accompanying drawings. First, a light projecting device and a light projecting lens according to one embodiment will be described with reference to FIGS. 2(a) and 2(b), the light source 2 is schematically shown as a point, and only the sections of the projection lens 11 are illustrated, and the portion seen behind the section is omitted. .

As shown in FIG. 1, the light projecting device 10 includes a light source 2 that emits near-infrared light, and a light source that diffuses the light from the light source 2 and emits it to the light projection side (opposite side to the light source 2). a lens 11; The light projecting device 10 is used for a light projecting system of an object detection device or a distance measuring device. The optical axis extending from the light source 2 to the projection lens 11 is defined as the Z-axis, and the axes orthogonal to the Z-axis and perpendicular to each other are defined as the X-axis and the Y-axis, respectively. A section containing the Z-axis and the X-axis is defined as an XZ section, and a section containing the Z-axis and the Y-axis is defined as a YZ section. In each drawing, these X-, Y-, and Z-axes are indicated by dashed lines.

The light source 2 is a laser diode element that emits a Gaussian beam of single-wavelength near-infrared light selected from the range of 750 to 1400 nm in the Z-axis direction. As illustrated in FIG. 3, the light emitted from the light source 2 has light intensity distributions in the XZ cross section and the YZ cross section that are symmetrical with respect to the Z axis, and the light intensity decreases as the distance from the Z axis increases. Further, the light emitted from the light source 2 has a divergence angle θ in the XZ cross section that is larger than the divergence angle θ in the YZ cross section, and the light projection range has an elliptical shape with the X axis as the major axis.

As shown in FIGS. 1, 2(a) and 2(b), the projection lens 11 is a single lens for projecting the light incident from the light source 2 over a wide range. The projection lens 11 converts and projects the light incident from the light source 2 so that the light projection range approaches a rectangular shape and the light intensity is ensured over substantially the entire projection range.

Since the light emitted from the light source 2 has a single wavelength, the projection lens 11 can be designed without considering chromatic aberration. Also, the projection lens 11 is made of a material having a refractive index of 1.56 or more at the wavelength of the light emitted from the light source 2 . As a result, the projection lens 11 can be miniaturized and widened.

The projection lens 11 includes an incident surface 12 on which light emitted from the light source 2 is incident, and an output surface 13 opposite to the incident surface 12 . The entrance surface 12 and the exit surface 13 intersect the Z axis, and the XZ cross section and the YZ cross section are formed line-symmetrically with respect to the Z axis. The XZ cross section of the incident surface 12 is necessarily a curved line, and the YZ cross section may be a straight line. Moreover, the exit surface 13 may always have a curved YZ cross section and may have a straight XZ cross section.

In this specification, the description of the shapes of the entrance surface 12 and the exit surface 13 relates to the inside of the effective diameter of each surface, and the shapes of the entrance surface 12 and the exit surface 13 outside the effective diameter can be set as appropriate. Note that the effective diameters of the incident surface 12 and the exit surface 13 are relative to 1/e ² (e: Napier's number) or more when the light intensity on the Z-axis is assumed to be 1 among the rays emitted from the light source 2 . This is the range through which a ray of intensity passes.

First, the XZ cross section and the YZ cross section of the entrance surface 12 and the exit surface 13 will be described. In the XZ cross section, the incident surface 12 is a curved line concave toward the light source 2, and the absolute value of the curvature decreases as the distance from the Z axis increases. Furthermore, in the XZ cross section, the absolute value of the curvature of the entrance surface 12 at the intersection of the Z axis and the entrance surface 12 is greater than the absolute value of the curvature of the exit surface 13 at the intersection of the Z axis and the exit surface 13 . Thereby, the light from the light source 2 can be spread mainly in the X-axis direction by the incident surface 12 .

In the YZ cross section, the exit surface 13 is a concave curve toward the light projection side (upper side of the paper surface in FIG. 2(b)). Furthermore, in the YZ cross section, the absolute value of the curvature of the entrance surface 12 at the intersection of the Z axis and the entrance surface 12 is smaller than the absolute value of the curvature of the exit surface 13 at the intersection of the Z axis and the exit surface 13 . Thereby, the light from the entrance surface 12 can be spread mainly in the Y-axis direction by the exit surface 13 .

In this way, the projection lens 11 expands the light from the light source 2 mainly in the X-axis direction by the entrance surface 12 to form a belt-like shape, and then spreads the long belt-like light in the X-axis direction by the exit surface 13 mainly in the Y direction. Spread axially. As a result, the projection range of the light that has passed through the projection lens 11 can be made closer to a rectangular shape.

Furthermore, according to such a projection lens 11, it is easy to individually set how to spread light in the X-axis direction and how to spread light in the Y-axis direction. Therefore, even if the divergence angle θ of the light from the light source 2 differs between the XZ cross section and the YZ cross section, the light projecting device 10 can easily bring the light projection range closer to a rectangular shape.

In addition, since the absolute value of the curvature of the incident surface 12 in the XZ cross section becomes smaller as the distance from the Z axis increases, the incident surface 12 greatly diffuses the light beam composed of a plurality of light rays from the light source 2 in the vicinity of the Z axis, It can be diffused to a small extent in the X-peripheral part away from the Z-axis in the X-axis direction. As a result, the light intensity of the light reaching the emission surface 13 can be reduced in the vicinity of the Z-axis and increased in the X-periphery.

Since the intensity of the light from the light source 2 decreases as the distance from the Z-axis increases, the intensity of the light that reaches the exit surface 13 from the light source 2 through the entrance surface 12 can be ensured over substantially the entire length in the X-axis direction. Since the ray bundle with such light intensity is spread mainly in the Y-axis direction by the exit surface 13, the light intensity of the light passing through the projection lens 11 can be ensured over substantially the entire rectangular projection range. Therefore, when the light projecting device 10 is used in the projection system of an object detection device that detects an object in a rectangular range, the detection range can be easily matched with the light projection range of the light projecting device 10. The intensity of the light can be increased, and the detection sensitivity can be improved.

The light from the light source 2 has a larger divergence angle θ in the XZ cross section than the divergence angle θ in the YZ cross section. Since the light intensity can be ensured by the incident surface 12 over substantially the entire length in the X-axis direction, which is easy to widen, the light intensity can be easily ensured over substantially the entire light projection range of the light projecting device 10 . In addition, the light from the light source 2, which is originally small in the Y-axis direction, is not greatly spread in the Y-axis direction by the entrance surface 12, but is largely spread in the Y-axis direction by the exit surface 13. It can be made compact in the axial direction.

The absolute value of the curvature of the output surface 13 in the YZ cross section becomes smaller as the distance from the Z axis increases. As a result, the output surface 13 can diffuse the ray bundle greatly in the vicinity of the Z-axis while diffusing it slightly in the Y-peripheral portion away from the Z-axis in the Y-axis direction. As a result, the light intensity of the light emitted from the exit surface 13 can be reduced in the vicinity of the Z-axis and increased in the Y-periphery. In particular, the light from the light source 2, whose light intensity decreases with distance from the Z axis, passes through the projection lens 11, which reduces the light intensity near the Z axis and increases it near the Y axis. The light intensity of the emitted light can be ensured over substantially the entire length in the Y-axis direction.

As described above, the light intensity of the light projected by the light projecting device 10 decreases near the Z-axis due to the entrance surface 12 and the exit surface 13, increases in the X-axis periphery due to the entrance surface 12, and reaches the exit surface 13. increases the Y perimeter. Therefore, the light projecting device 10 can approximate the isointensity lines of the light intensity to a rectangular shape within the light projection range that is approximated to a rectangular shape.

The exit surface 13 in the XZ cross section is preferably formed by a curved line that is concave toward the light projection side in the vicinity of the Z axis and convex toward the light projection side at a position away from the Z axis. As a result, the ray bundle emitted from the exit surface 13 can be diffused to a smaller extent in the X peripheral portion, so that the light intensity in the X peripheral portion can be further increased.

In particular, in the XZ cross section of the output surface 13, the distance in the X-axis direction from the Z-axis to the inflection point that changes from concave to convex is the effective diameter (1/e2 relative intensity emitted from the light source ² ) from the Z-axis. When the distance in the X-axis direction to the position through which the light ray passes) is taken as 100%, it is preferably 75% or less. As a result, the ray bundle emitted from the exit surface 13 can be diffused to a small extent in a wide range of the X peripheral portion, so that the light intensity of the X peripheral portion can be further increased.

It is preferable that the absolute value of the curvature of the XZ cross section at the intersection of the Z axis and the incidence surface 12 is larger than the absolute value of the curvature of the YZ cross section at the intersection of the Z axis and the incidence surface 12 . As a result, the incident surface 12 can diffuse the light to a small extent in the Y-axis direction and a large extent in the X-axis direction. Moreover, it is preferable that the absolute value of the curvature of the YZ section at the intersection of the Z axis and the emission surface 13 is larger than the absolute value of the curvature of the XZ section at the intersection of the Z axis and the emission surface 13 . As a result, the light can be diffused slightly in the X-axis direction and greatly in the Y-axis direction by the exit surface 13 .

As a result, the role of spreading the light from the light source 2 in the X-axis direction and the role of spreading the light in the Y-axis direction can be easily shared between the entrance surface 12 and the exit surface 13, respectively. Therefore, it is possible to make the projection range of the light passing through the projection lens 11 closer to a rectangular shape and to easily secure the light intensity within the projection range.

Next, the overall shape of the entrance surface 12 and the exit surface 13 will be described. The entrance surface 12 and the exit surface 13 are preferably anamorphic surfaces formed symmetrically with respect to the XZ cross section and the YZ cross section, respectively. The anamorphic plane includes a toroidal plane having curved cross sections perpendicular to both the X-axis direction and the Y-axis direction, and a straight cross section perpendicular to either the X-axis direction or the Y-axis direction, and a cylindrical surface having a curved cross-section perpendicular to either the X-axis direction or the Y-axis direction.

The intersection of the Z-axis and each surface is the origin, the distance in the X-axis direction is x, the distance in the Y-axis direction is y, and the distance in the Z-axis direction is z. A cylindrical surface represented by the formula (1) and having a linear cross section perpendicular to the X-axis direction is represented by the following formula (2). z becomes a positive value at a position closer to the light projection side than the origin. Also, the formula showing the shape of the cylindrical surface whose cross section perpendicular to the Y-axis direction is linear is obtained by changing _x to _y , _cx to _cy , and kx to ky in formula (2). be.

但し、
ｃ_ｘ：ＸＺ断面とＺ軸との交点におけるＸＺ断面の曲率
ｃ_ｙ：ＹＺ断面とＺ軸との交点におけるＹＺ断面の曲率
ｋ_ｘ：ＸＺ断面のコーニック定数
ｋ_ｙ：ＹＺ断面のコーニック定数
Ａ，Ｂ，Ｃ，Ｄ，Ａ_ｉ，Ｂ_ｉ：非球面係数（ｉは４～２０の範囲の偶数）

however,
cx: the curvature of the XZ cross section at the intersection of the XZ cross section and the Z _{axis cy} : the curvature of the YZ cross section at the intersection of the YZ cross section and the Z _axis kx: the conic constant of the XZ cross section _ky : the conic constant of the YZ cross section A, B, C, D, A _i , B _i : aspheric coefficients (i is an even number in the range of 4 to 20)

If both the entrance surface 12 and the exit surface 13 are anamorphic surfaces, it is possible to easily set how the light spreads on the entrance surface 12 in the X-axis direction and how the light spreads in the Y-axis direction. It is possible to easily individually set how to spread the light in the X-axis direction and how to spread the light in the Y-axis direction on the exit surface 13 . As a result, the projection lens 11 for securing the light intensity within the light projection range can be easily designed while the light projection range of the light projection device 10 is brought closer to a rectangular shape.

Furthermore, since both the entrance surface 12 and the exit surface 13 are anamorphic surfaces, while setting how to spread the light in the Y-axis direction over the entire X-axis direction, It is possible to set how to spread the light of, and to set those settings individually. As a result, the light projecting device 10 can easily approximate the isointensity lines of the light intensity to a rectangular shape within the light projection range approximated to a rectangular shape.

More preferably, one of the entrance surface 12 and the exit surface 13 is a cylindrical surface and the other is a toroidal surface. As a result, the cylindrical surface, which is easier to form than the toroidal surface and has low error sensitivity, can easily diffuse light in one direction, and the toroidal surface can diffuse light in one direction while diffusing light in another direction. You can adjust how it spreads. As a result, the projection range of the light that has passed through the projection lens 11 can be easily adjusted into a rectangular shape, and the light intensity within the projection range can be easily secured. In addition, the isointensity lines of the light intensity within the light projection range can be easily approximated to a rectangular shape.

Next, the path of light rays emitted from the light source 2 will be described in more detail with reference to FIGS. 2(a) and 2(b). As shown in FIG. 2A, in the XZ cross section, light rays emitted from the light source 2 are refracted by the entrance surface 12 and the exit surface 13, respectively, to form a path of one light ray. For the path of one ray in this XZ cross section, each line and each angle are defined as follows.

A ray from the light source 2 to the incident surface 12 is defined as an X ray 14 . A first X refracted ray 15 is the X ray 14 incident on the incident surface 12 and refracted. A virtual line extending the X-ray 14 is defined as a first X-extended line 16 . A second X refracted ray 17 is obtained by refracting the first X refracted ray 15 incident on the exit surface 13 . A virtual line obtained by extending the first X refracted ray 15 is assumed to be a second X extension line 18 .

The angle between the X ray 14 and the normal 19 of the incident surface 12 at the position where the X ray 14 is incident is defined as an incident angle α1. The angle between the first X refracted ray 15 and the normal 19 of the incident surface 12 at the position where the first X refracted ray 15 intersects is defined as a refraction angle α2. The angle between the first X refracted ray 15 and the normal 20 of the exit surface 13 at the position where the first X refracted ray 15 is incident is defined as an incident angle α3. The angle between the second X refracted ray 17 and the normal 20 of the exit surface 13 at the position where the first X refracted ray 17 intersects is defined as a refraction angle α4. The angle between the first X refracted ray 15 and the first X extension line 16 at the position where the first X refracted ray 15 intersects on the plane of incidence 12 is defined as a first X deflection angle α5. The angle between the second X refracted ray 17 and the second X extension line 18 at the position where the second X refracted ray 17 intersects on the exit surface 13 is defined as a second X deflection angle α6.

In the XZ cross section, the X rays 14 include X inner rays whose divergence angle θ is greater than 0° and equal to or less than half angle at half maximum. The half-maximum angle of the X-ray 14 is the angle between the Z-axis and a ray having a relative intensity of 0.5 when the intensity of the light on the Z-axis is set to 1 in the X-ray 14 .

When the incident surface 12 in the XZ cross section is a concave curve toward the light source 2 side, the incident angle α1 of the X inner ray on the incident surface 12 increases as the incident position of the X inner ray on the incident surface 12 moves away from the Z axis. It is preferable to set the entrance surface 12 and the exit surface 13 in such a shape that each path formed by the X inner ray satisfies the following two conditions when the light source 2 is placed at a position of .

The first condition is that the first X refracted ray 15 is positioned on the side opposite to the Z axis with respect to the first X extension line 16, and the second X refracted ray 17 is positioned on the second X extension line 18 opposite to the Z axis. It is to be located on the side. The second condition is that as the incident position of the X inner ray on the incident surface 12 is away from the Z axis, the first X deflection angle α5 increases, and the incident position of the first X refracted ray 15 on the exit surface 13 is away from the Z axis. The difference is that the second X argument α6 increases as the distance increases. By satisfying these conditions, the X inner ray can be diffused over a wide range in the X-axis direction, and the projection lens 11 can be widened in the X-axis direction.

Next, in the YZ cross section shown in FIG. 2B, similarly, the light beam emitted from the light source 2 is refracted by the entrance surface 12 and the exit surface 13, forming a path of one light beam. Regarding the path of one ray in this YZ section, each line and each angle are defined as follows.

A ray from the light source 2 to the incident surface 12 is assumed to be a Y ray 22 . A first Y refracted ray 23 is a ray of the Y ray 22 incident on the incident surface 12 and refracted. A virtual line obtained by extending the Y ray 22 is defined as a first Y extension line 24 . A second Y refracted ray 25 is a ray obtained by refracting the first Y refracted ray 23 incident on the exit surface 13 . A virtual line obtained by extending the first Y refracted ray 23 is assumed to be a second Y extension line 26 .

The angle between the Y ray 22 and the normal 27 of the incident surface 12 at the position where the Y ray 22 is incident is defined as an incident angle β1. The angle between the first Y-refracted ray 23 and the normal 27 of the incident surface 12 at the position where the first Y-refracted ray 23 intersects is defined as a refraction angle β2. The angle between the first Y-refracted ray 23 and the normal 28 of the exit surface 13 at the position where the first Y-refracted ray 23 is incident is defined as an incident angle β3. The angle between the second Y-refracted light ray 25 and the normal line 28 of the exit surface 13 at the position where the second Y-refracted light ray 25 intersects is defined as a refraction angle β4. The angle between the first Y refracted light ray 23 and the first Y extension line 24 at the position where the first Y refracted light ray 23 intersects on the plane of incidence 12 is defined as a first Y deflection angle β5. The angle between the second Y refracted light ray 25 and the second Y extension line 26 at the position where the second Y refracted light ray 25 intersects on the output surface 13 is defined as a second Y deflection angle β6.

Since the incident surface 12 in the YZ cross section may be a straight line, the second Y refracted ray 25 is positioned on the opposite side of the Z axis with respect to the second Y extension line 26, and the incident position of the first Y refracted ray 23 on the exit surface 13 is It is preferable that the shape of the output surface 13 is set such that the second Y deflection angle β6 increases as the distance from the Z axis increases. As a result, the Y ray 22 can be diffused over a wide range in the Y-axis direction by the exit surface 13, so that the angle of the projection lens 11 can be widened in the Y-axis direction.

Similarly, in the YZ cross section, the Y light ray 22 includes the Y inner light ray whose divergence angle θ is greater than 0° and equal to or less than half angle at half maximum. The half-value half angle of the Y ray 22 is the angle between the Z axis and a ray of the Y ray 22 having a relative intensity of 0.5 when the intensity of the light on the Z axis is 1.

The YZ section of the incident surface 12 may be formed by a curved line. At this time, in the YZ cross section, when the light source 2 is placed at a position where the incident angle β1 of the Y inner ray to the incident surface 12 increases as the incident position of the Y inner ray to the incident surface 12 moves away from the Z axis, It is preferable to set the incident surface 12 in a shape in which each path formed by the Y inner ray satisfies the following two conditions.

The first condition is that the first Y refracted ray 23 is positioned on the opposite side of the first Y extension line 24 from the Z axis. The second condition is that the first Y deflection angle β5 increases as the incident position of the Y inner ray on the incident surface 12 moves away from the Z axis. By satisfying these conditions, even if the YZ cross section of the incident surface 12 is curved, the inner light rays can be diffused over a wide range in the Y-axis direction, and the angle of the projection lens 11 can be widened in the Y-axis direction.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Descriptions common to each embodiment will be described only for the first embodiment, and descriptions for the other embodiments will be omitted.

(First embodiment)
As shown in FIGS. 1, 2(a) and 2(b), the projection device 10 in the first embodiment comprises a light source 2 and one projection lens 11. As shown in FIG. The light source 2 is a laser diode element that emits near-infrared light with a peak wavelength of 905 nm having the light intensity distribution shown in FIG. 3 in the Z-axis direction. The light source 2 is arranged so that the light intensity of the light from the light source 2 is maximized on the Z-axis. In a cross section perpendicular to the Z-axis, the projection range of light from the light source 2 has an elliptical shape with the X-axis as the major axis.

In the light intensity distribution diagram shown in FIG. 3, the horizontal axis represents the divergence angle θ (°=deg) from the Z-axis. The vertical axis in FIG. 3 represents the relative intensity of light (RELATIVE INTENSITY) when the intensity of light on the Z-axis (where the divergence angle θ is 0°) is set to 1. As shown in FIG. A solid line indicates the light intensity distribution in the XZ cross section, and a broken line indicates the light intensity distribution in the YZ cross section.

In the XZ cross section, the half-value half angle, which is the divergence angle θ when the relative intensity is 0.5, is about 15°, and the divergence angle θ when the relative intensity is 1/e ² (about 0.135) is about 27°. In the YZ cross section, the half angle at half maximum, which is the divergence angle θ when the relative intensity is 0.5, is about 8°, and the divergence angle θ when the relative intensity is 1/e ² is about 13°.

The projection lens 11 includes an incident surface 12 formed by a cylindrical surface having a linear cross section perpendicular to the X-axis direction, and an exit surface 13 formed by a toroidal surface. The distance on the Z-axis from the light source 2 to the entrance surface 12 is 10.5 mm, and the distance on the Z-axis from the entrance surface 12 to the exit surface 13 is 4.7 mm. The projection lens 11 is made of a synthetic resin having a refractive index of 1.63 for light with a wavelength of 905 nm.

Table 1 shows the optical values and lens data of this projection lens 11 . In this specification, some values are expressed using E as a power of 10 (eg, 1.0×10 ⁻⁴ is 1.0E−4). Constants that are shown in formulas (1) and (2) but not listed in Table 1 are assumed to be zero.

The shapes of the entrance surface 12 and the exit surface 13 obtained by substituting the optical values shown in Table 1 into the equations (1) and (2) are as follows. The XZ cross section of the incident surface 12 is a concave curve toward the light source 2 side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The XZ cross section of the output surface 13 is formed by a curve that is concave toward the light projection side near the Z axis and convex toward the light projection side at a position away from the Z axis. The distance in the X-axis direction from the Z-axis to the point of inflection where the concave changes to convex is 40% when the distance in the X-axis direction from the Z-axis to the effective diameter is 100%. The YZ cross section of the output surface 13 is a concave curve toward the light projection side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The absolute value _0.667 of the curvature cx of the XZ cross section of the entrance surface 12 is larger than the absolute value 0.004 of the curvature _cx of the XZ cross section of the exit surface 13, and the curvature of the YZ cross section of the entrance surface 12 is linear. Greater than 0. The absolute value 0.417 of the curvature of the YZ cross section c _y of the exit surface 13 is greater than the curvature 0 of the YZ cross section of the entrance surface 12 and greater than the absolute value 0.004 of the curvature c _x of the XZ cross section of the exit surface 13 . .

FIG. 4A shows a relationship diagram of the incident angle α1, the refraction angle α2, the first X deflection angle α5 on the XZ cross section of the incident surface 12, and the divergence angle θ on the XZ cross section. FIG. 4B shows a relationship diagram of the incident angle α3, the refraction angle α4, the second X deflection angle α6 on the XZ cross section of the output surface 13, and the divergence angle θ on the XZ cross section. FIG. 4C shows a relationship diagram of the incident angle β3, the refraction angle β4, the second Y deflection angle β6 in the YZ section of the exit surface 13, and the divergence angle θ in the YZ section.

4(a), 4(b), and 4(c), the horizontal axis is the divergence angle θ, and the vertical axis is each angle (deg) in the cross section. It is approximated that the larger the divergence angle θ on the horizontal axis, the farther the incident position of the light beam on each cross section from the Z-axis. In each drawing, a solid line represents a graph of incident angles, a broken line represents a graph of refraction angles, and a dashed line represents a graph of deflection angles. Furthermore, in each drawing, the position A of the half-value half-value angle and the position B of the divergence angle θ when the relative intensity is 1/e ² are indicated by two-dot chain lines.

If the first X refracted ray 15 is positioned on the opposite side of the Z axis with respect to the first X extension line 16, then the first X deflection angle α5 is a positive value. Similarly, when the second X refracted ray 17 is positioned on the opposite side of the second X extension line 18 from the Z axis, the second X deflection angle α6 is a positive value, and the second Y refracted ray 25 is positioned on the second Y extension line 26, the second Y deflection angle β6 is a positive value.

As shown in FIGS. 4A and 4B, the first X argument α5 and the second X argument α6 are positive values. In addition, in the range where the divergence angle θ is smaller than the position A, that is, in the range where the X inner ray is incident on the incident surface 12, as the divergence angle θ increases, the incident angle α1, the first X deflection angle α5 and the second X deflection angle The angle α6 becomes large. As a result, the first X refracted light ray 15 and the second X refracted light ray 17 refracted from the X inner light ray can be diffused over a wide range in the X-axis direction by the entrance surface 12 and the exit surface 13 . As a result, it can be seen that the angle of projection lens 11 can be widened in the X-axis direction.

Furthermore, in a range where the divergence angle θ is smaller than the position A, as the divergence angle θ increases, the rate of increase of the first X argument α5 decreases. Within this range, it can be seen that the distance between the first X refracted light beams 15 emitted from the incident surface 12 can be made smaller as the distance from the Z-axis in the X-axis direction increases. Similarly, in a range where the divergence angle θ is smaller than the position A, as the divergence angle θ increases, the rate of increase of the second X deflection angle α6 decreases. It can be seen that the spacing can be made smaller with increasing distance from the Z-axis in the X-axis direction.

Also, as the divergence angle θ increases, the first X argument α5 and the second X argument α6 between the position A and the position B change from increasing to decreasing. In the range where the first X deflection angle α5 and the second X deflection angle α6 decrease, the interval between the first X refracted rays 15 emitted from the entrance surface 12 and the interval between the second X refracted rays 17 emitted from the exit surface 13 are can be made smaller as it moves away from the Z-axis in the X-axis direction.

Also, as shown in FIG. 4(c), the second Y deviation angle β6 is a positive value, and the second Y deviation angle β6 increases as the divergence angle θ increases. As a result, the second Y-refracted light ray 25 can be diffused over a wide range in the Y-axis direction by the exit surface 13, and the angle of the projection lens 11 can be widened in the Y-axis direction. Furthermore, as the divergence angle θ increases, the rate of increase of the second Y deflection angle β6 decreases. I know you can.

Although not shown, the absolute values of the incident angle β1, the refraction angle β2, and the first Y deflection angle β5 in the YZ section of the linear incident surface 12 increase in proportion to the increase in the divergence angle θ in the YZ section. Since the first Y refracted ray 23 is positioned on the Z-axis side with respect to the first Y extension line 24, the first Y deflection angle β5 is a negative value.

Next, FIG. 5A shows the outline of the projection range of the light projected from the light projection device 10 of the first embodiment onto a predetermined spherical surface centered on the light source 2. As shown in FIG. The vertical axis in FIG. 5A is the angle (Y ANGLE (deg)) between the light beam emitted from the light projecting device 10 and the XZ cross section in the Y-axis direction. The horizontal axis of FIG. 5A is the angle (X ANGLE (deg)) in the X-axis direction between the light beam emitted from the light projecting device 10 and the YZ cross section. The Z-axis is the position where the angle in the X-axis direction and the angle in the Y-axis direction are 0°.

The light projecting device 10 can form the elliptical light from the light source 2 into a long rectangular shape (rectangular shape) in the X-axis direction by the light projecting lens 11, as shown in FIG. 5(a). In addition, since the light from the light source 2, the incident surface 12 and the emitting surface 13 are symmetrical with respect to the XZ cross section and the YZ cross section, the light intensity distribution within the light projection range by the light projecting device 10 is can be symmetrical with respect to

In the light projection range of the light projecting device 10, the solid line represents the light intensity distribution in the X-axis direction when the angle in the Y-axis direction is 0°, and the light intensity in the X-axis direction when the angle in the Y-axis direction is ±20°. The distribution is shown in FIG. 5B by a broken line, the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is 0° is shown in a solid line, and the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is ±45°. The light intensity distribution is shown by a dashed line in FIG. 5(c). The vertical axes in FIGS. 5B and 5C are relative light intensity (RELATIVE INTENSITY (%)) when the highest light intensity in the light projection range of the light projecting device 10 is taken as 100%. be. The horizontal axis in FIG. 5B is the angle in the X-axis direction, and the horizontal axis in FIG. 5C is the angle in the Y-axis direction.

As shown in FIGS. 5(b) and 5(c), the light projecting device 10 can secure the light intensity so that the relative intensity is 50% or more over substantially the entire light projection range. Furthermore, the light projecting device 10 can reduce the light intensity in the vicinity of the Z-axis and increase the light intensity in the peripheral part away from the Z-axis.

(Second embodiment)
As shown in FIGS. 6A and 6B, the projection device 30 in the second embodiment includes a light source 2 and one projection lens 31. As shown in FIGS. The projection lens 31 has an incident surface 32 formed by a cylindrical surface having a linear cross section perpendicular to the X-axis direction, and an exit surface 33 formed by a cylindrical surface having a linear cross section perpendicular to the Y-axis direction. and have. The distance on the Z-axis from the light source 2 to the incident surface 32 is 10.0 mm, and the distance on the Z-axis from the incident surface 32 to the exit surface 33 is 4.1 mm. The projection lens 31 is made of synthetic resin having a refractive index of 1.63 for light with a wavelength of 905 nm.

Table 2 shows the optical values and lens data of this projection lens 31 . Constants that are shown in formula (2) and the like but not listed in Table 2 are assumed to be zero.

The shapes of the entrance surface 32 and the exit surface 33 obtained by substituting the optical values shown in Table 2 into the formula (2) are as follows. The XZ cross section of the incident surface 32 is a curved line concave toward the light source 2, and the absolute value of the curvature decreases as the distance from the Z axis increases. The YZ cross section of the output surface 33 is a concave curve toward the light projection side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The absolute value 0.435 of the curvature c _x of the XZ cross section of the incident surface 32 is larger than the curvature 0 of the linear XZ cross section of the exit surface 33 and larger than the curvature 0 of the linear YZ cross section of the incident surface 32. big. The absolute value _0.091 of the curvature of the YZ cross section cy of the exit surface 33 is larger than the curvature 0 of the YZ cross section of the entrance surface 32 and larger than the curvature 0 of the XZ cross section of the exit surface 33 .

In addition, the relationship diagram between the incident angle α1, the refraction angle α2, the first X deflection angle α5 in the XZ cross section of the incident surface 32, and the divergence angle θ in the XZ cross section is a range where the divergence angle θ is smaller than the position A. Except that the first X argument α5 changes from increasing to decreasing as θ increases, it has been confirmed that the behavior is substantially the same as in the relationship diagram of Example 1 shown in FIG. 4(a). Illustration and description thereof are omitted. Similarly, the relationship diagram of the incident angle β3, the refraction angle β4, the second Y deflection angle β6 in the YZ cross section of the output surface 33, and the divergence angle θ in the YZ cross section shows that the divergence angle θ Except that the second Y argument β6 changes from increasing to decreasing as the angle θ increases, it has been confirmed that the behavior is substantially the same as that of the relationship diagram of Example 1 shown in FIG. 4(c). , the illustration and description thereof will be omitted.

Also, the absolute values of the incident angle α3, the refraction angle α4, and the second X deflection angle α6 in the XZ cross section of the linear exit surface 33 increase in proportion to the increase in the divergence angle θ in the XZ cross section. The absolute values of the incident angle β1, the refraction angle β2, and the first Y deflection angle β5 in the YZ section of the linear incident surface 32 increase in proportion to the increase in the divergence angle θ in the YZ section. The second X argument α6 has a positive value, and the first Y argument β5 has a negative value.

Next, FIG. 7A shows the outline of the light projection range of the light projected from the light projection device 30 of the second embodiment onto a predetermined spherical surface centered on the light source 2 . The light projecting device 30 can form the elliptical light from the light source 2 into a long rectangular shape (rectangular shape) in the X-axis direction by the light projecting lens 31, as shown in FIG. 7(a).

In the light projection range of the light projecting device 30, the solid line represents the light intensity distribution in the X-axis direction when the angle in the Y-axis direction is 0°, and the light intensity in the X-axis direction when the angle in the Y-axis direction is ±10°. The distribution is shown in FIG. 7B by a broken line, the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is 0° is shown in a solid line, and the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is ±40°. The light intensity distribution is shown by a dashed line in FIG. 7(c). As shown in FIGS. 7(b) and 7(c), the light projection device 30 can ensure the light intensity so that the relative intensity is 50% or more over substantially the entire light projection range.

(Third embodiment)
As shown in FIGS. 8A and 8B, the projection device 40 in the third embodiment includes the light source 2 and one projection lens 41. As shown in FIGS. The projection lens 41 has an incident surface 42 formed by a cylindrical surface having a linear cross section perpendicular to the X-axis direction, and an exit surface 43 formed by a cylindrical surface having a linear cross section perpendicular to the Y-axis direction. and have. The distance on the Z-axis from the light source 2 to the entrance surface 42 is 10.0 mm, and the distance on the Z-axis from the entrance surface 42 to the exit surface 43 is 4.1 mm. The projection lens 41 is made of a synthetic resin having a refractive index of 1.63 for light with a wavelength of 905 nm.

Table 3 shows the optical values and lens data of the projection lens 41. Constants that are shown in formula (2) and the like but not listed in Table 3 are assumed to be zero.

The shapes of the entrance surface 42 and the exit surface 43 obtained by substituting the optical values shown in Table 3 into the formula (2) are as follows. The XZ cross section of the incident surface 42 is a curved line concave toward the light source 2, and the absolute value of the curvature decreases as the distance from the Z axis increases. The YZ cross section of the output surface 43 is a curved line concave toward the light projection side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The absolute value 0.435 of the curvature c _x of the XZ cross section of the entrance surface 42 is larger than the curvature 0 of the linear XZ cross section of the exit surface 43 and larger than the curvature 0 of the linear YZ cross section of the entrance surface 42. big. The absolute value 0.333 of the curvature of the YZ cross section _cy of the exit surface 43 is larger than the curvature 0 of the YZ cross section of the entrance surface 42 and larger than the curvature 0 of the XZ cross section of the exit surface 43 .

In addition, the relationship diagram of the incident angle α1, the refraction angle α2, the first X deflection angle α5 in the XZ cross section of the incident surface 42, and the divergence angle θ in the XZ cross section is a range where the divergence angle θ is smaller than the position A. Except that the first X argument α5 changes from increasing to decreasing as θ increases, it has been confirmed that the behavior is substantially the same as in the relationship diagram of Example 1 shown in FIG. 4(a). Illustration and description thereof are omitted. Similarly, the relationship diagram of the incident angle β3, the refraction angle β4, the second Y deflection angle β6 in the YZ cross section of the output surface 43, and the divergence angle θ in the YZ cross section is the relationship of Example 1 shown in FIG. Since it has been confirmed that the behavior is substantially the same as that shown in the figure, illustration and description thereof are omitted.

Also, the absolute values of the incident angle α3, the refraction angle α4, and the second X deflection angle α6 in the XZ cross section of the linear exit surface 43 increase in proportion to the increase in the divergence angle θ in the XZ cross section. The absolute values of the incident angle β1, the refraction angle β2, and the first Y deflection angle β5 in the YZ section of the linear incident surface 42 increase in proportion to the increase in the divergence angle θ in the YZ section. The second X argument α6 has a positive value, and the first Y argument β5 has a negative value.

Next, FIG. 9A shows the outline of the light projection range of the light projected from the light projection device 40 of the third embodiment on a predetermined spherical surface centered on the light source 2 . The light projecting device 40 converts the elliptical light from the light source 2 with the light projecting lens 41, and as shown in FIG. be able to. Specifically, the projection range can be made closer to a rectangular shape with corners extending diagonally outward.

In the light projection range of the light projecting device 40, the solid line represents the light intensity distribution in the X-axis direction when the angle in the Y-axis direction is 0°, and the light intensity in the X-axis direction when the angle in the Y-axis direction is ±20°. The distribution is shown in FIG. 9B by a broken line, the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is 0° is shown in a solid line, and the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is ±40°. The light intensity distribution is shown by a dashed line in FIG. 9(c). As shown in FIGS. 9(b) and 9(c), the light projecting device 40 can secure the light intensity so that the relative intensity is 50% or more over substantially the entire light projection range.

(Fourth embodiment)
As shown in FIGS. 10(a) and 10(b), the projection device 50 in the fourth embodiment includes a light source 2 and one projection lens 51. As shown in FIGS. The projection lens 51 has an incident surface 52 formed by a cylindrical surface having a linear cross section perpendicular to the X-axis direction, and an exit surface 53 formed by a cylindrical surface having a linear cross section perpendicular to the Y-axis direction. and have. The distance on the Z-axis from the light source 2 to the entrance surface 52 is 10.5 mm, and the distance on the Z-axis from the entrance surface 52 to the exit surface 53 is 4.1 mm. The projection lens 51 is made of synthetic resin having a refractive index of 1.63 for light with a wavelength of 905 nm.

Table 4 shows the optical values and lens data of the projection lens 51. Constants that are shown in formula (2) and the like but not listed in Table 4 are assumed to be zero.

The shapes of the entrance surface 52 and the exit surface 53 obtained by substituting the optical values shown in Table 4 into Equation (2) are as follows. The XZ cross section of the incident surface 52 is a curved line concave toward the light source 2, and the absolute value of the curvature decreases as the distance from the Z axis increases. The YZ cross section of the output surface 53 is a concave curve toward the light projection side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The absolute value _0.714 of the curvature cx of the XZ cross section of the entrance surface 52 is larger than the curvature 0 of the linear XZ cross section of the exit surface 53 and larger than the curvature 0 of the linear YZ cross section of the entrance surface 52. big. The absolute value _0.357 of the curvature of the YZ cross section cy of the exit surface 53 is larger than the curvature 0 of the YZ cross section of the entrance surface 52 and larger than the curvature 0 of the XZ cross section of the exit surface 53 .

In addition, the relationship diagram of the incident angle α1, the refraction angle α2, the first X deflection angle α5 in the XZ cross section of the incident surface 52, and the divergence angle θ in the XZ cross section is a range where the divergence angle θ is smaller than the position A. Except that the first X argument α5 changes from increasing to decreasing as θ increases, it has been confirmed that the behavior is substantially the same as in the relationship diagram of Example 1 shown in FIG. 4(a). Illustration and description thereof are omitted. Similarly, the relationship diagram of the incident angle β3, the refraction angle β4, the second Y deflection angle β6 in the YZ cross section of the output surface 53, and the divergence angle θ in the YZ cross section is the relationship of Example 1 shown in FIG. Since it has been confirmed that the behavior is substantially the same as that shown in the figure, illustration and description thereof are omitted.

Also, the absolute values of the incident angle α3, the refraction angle α4, and the second X deflection angle α6 in the XZ cross section of the linear exit surface 53 increase in proportion to the increase in the divergence angle θ in the XZ cross section. The absolute values of the incident angle β1, the refraction angle β2, and the first Y deflection angle β5 in the YZ section of the linear incident surface 52 increase in proportion to the increase in the divergence angle θ in the YZ section. The second X argument α6 has a positive value, and the first Y argument β5 has a negative value.

Next, FIG. 11A shows the outline of the light projection range of the light projected from the light projection device 50 of the fourth embodiment onto a predetermined spherical surface centered on the light source 2 . The light projecting device 50 converts the elliptical light from the light source 2 with the light projecting lens 51, and as shown in FIG. be able to.

In the light projection range of the light projecting device 50, the solid line represents the light intensity distribution in the X-axis direction when the angle in the Y-axis direction is 0°, and the light intensity in the X-axis direction when the angle in the Y-axis direction is ±20°. The distribution is shown in FIG. 11B by a broken line, the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is 0° is shown in a solid line, and the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is ±45°. The light intensity distribution is shown by a dashed line in FIG. 11(c). As shown in FIGS. 11(b) and 11(c), the light projecting device 50 can secure the light intensity so that the relative intensity is 50% or more over substantially the entire light projection range.

(Fifth embodiment)
As shown in FIGS. 12( a ) and 12 ( b ), the projection device 60 in the fifth embodiment has a light source 2 and one projection lens 61 . The projection lens 61 includes an incident surface 62 formed by a cylindrical surface having a linear cross section perpendicular to the X-axis direction, and an exit surface 63 formed by a toroidal surface. The distance on the Z-axis from the light source 2 to the incident surface 62 is 10.5 mm, and the distance on the Z-axis from the incident surface 62 to the exit surface 63 is 4.1 mm. The projection lens 61 is made of synthetic resin having a refractive index of 1.63 for light with a wavelength of 905 nm.

Table 5 shows the optical values and lens data of the projection lens 61. Constants shown in formulas (1) and (2) but not listed in Table 5 are set to zero.

The shapes of the entrance surface 62 and the exit surface 63 obtained by substituting the optical values shown in Table 5 into the equations (1) and (2) are as follows. The XZ cross section of the incident surface 62 is a curved line concave toward the light source 2, and the absolute value of the curvature decreases as the distance from the Z axis increases. The XZ cross section of the emission surface 63 is formed by a curved line that is convex toward the light projection side in the vicinity of the Z axis. The YZ cross section of the output surface 63 is a concave curve toward the light projection side, and the absolute value of the curvature decreases as the distance from the Z axis increases.

The absolute value _0.714 of the curvature _cx of the XZ cross section of the entrance surface 62 is larger than the absolute value 0.002 of the curvature cx of the XZ cross section of the exit surface 63, and the curvature of the YZ cross section of the entrance surface 62 is linear. Greater than 0. The absolute value 0.417 of the curvature of the YZ cross section c _y of the exit surface 63 is larger than the curvature 0 of the YZ cross section of the entrance surface 62 and larger than the absolute value 0.002 of the curvature c _x of the XZ cross section of the exit surface 63 . .

The relationship diagram of the incident angle α1, the refraction angle α2, the first X deflection angle α5 in the XZ cross section of the incident surface 62, and the divergence angle θ in the XZ cross section is the relationship diagram of the first embodiment shown in FIG. Since it has been confirmed that the behavior is substantially the same as that of , illustration and description thereof are omitted. Similarly, the relationship diagram of the incident angle α3, the refraction angle α4, the second X deflection angle α6 in the XZ cross section of the output surface 63, and the divergence angle θ in the XZ cross section is the relationship of the first embodiment shown in FIG. Since it has been confirmed that the behavior is substantially the same as that shown in the figure, illustration and description thereof are omitted.

Similarly, the relationship diagram of the incident angle β3, the refraction angle β4, the second Y deflection angle β6 in the YZ cross section of the output surface 63, and the divergence angle θ in the YZ cross section is the relationship of Example 1 shown in FIG. Since it has been confirmed that the behavior is substantially the same as that shown in the figure, illustration and description thereof are omitted. Also, the absolute values of the incident angle β1, the refraction angle β2, and the first Y deflection angle β5 in the YZ section of the linear incident surface 62 increase in proportion to the increase in the divergence angle θ in the YZ section. Note that the first Y argument β5 is a negative value.

Next, FIG. 13A shows the outline of the light projection range of the light projected from the light projection device 60 of the fifth embodiment onto a predetermined spherical surface centered on the light source 2 . The light projecting device 60 converts the elliptical light from the light source 2 with the light projecting lens 61, and as shown in FIG. be able to. Specifically, the projection range can be made closer to a rectangular shape with the corners extending outward in the X-axis direction.

In the light projection range of the light projecting device 60, the solid line represents the light intensity distribution in the X-axis direction when the angle in the Y-axis direction is 0°, and the light intensity in the X-axis direction when the angle in the Y-axis direction is ±20°. The distribution is shown in FIG. 13B by a broken line, the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is 0° is shown in a solid line, and the light intensity distribution in the Y-axis direction when the angle in the X-axis direction is ±45°. The light intensity distribution is shown by a dashed line in FIG. 13(c). As shown in FIGS. 13(b) and 13(c), the light projecting device 60 can secure the light intensity so that the relative intensity is 50% or more over substantially the entire light projection range.

Next, the above Examples 1 to 5 are compared. In Example 2, in which the projection range in the Y-axis direction is narrow, the projection range can be made rectangular. Compared with the projection range of the second embodiment, the projection range is farther from the rectangular shape. On the other hand, in contrast to Examples 2 to 4, in Examples 1 and 5, the light projection range can be widened in the Y-axis direction, and the light projection range can be made closer to a rectangular shape. It is possible to easily secure the light intensity over the entire area. Here, the exit surfaces 33, 43 and 53 of Examples 2 to 4 are cylindrical surfaces, while the exit surfaces 13 and 63 of Examples 1 and 5 are toroidal surfaces. As a result, by using the toroidal surface, even if the light projection range of the light projection devices 10 and 60 is widened, the light projection range can be easily approximated to a rectangular shape. can be easily secured.

Compared to Example 5 in which the vicinity of the Z axis of the XZ cross section of the output surface 63 is a convex curve toward the light projection side, in Example 1 in which the vicinity of the Z axis of the XZ cross section of the output surface 13 is a concave curve toward the light projection side. Thus, it is possible to easily secure the light intensity over substantially the entire projection range while making the projection range closer to a rectangular shape. Therefore, by forming the vicinity of Z of the XZ cross section of the emission surface 13 as a concave curve toward the light projection side, the light projection range of the light projection device 10 can be easily approximated to a rectangular shape, and substantially the entire light projection range can be It can be seen that the light intensity can be easily secured.

Although the present invention has been described above based on the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various improvements and modifications are possible without departing from the scope of the present invention. It can be easily inferred that A lens having almost no refractive power (cover glass or the like) may be provided on the light source 2 side or the light projection side of the projection lenses 11, 31, 41, 51, and 61.

Although the light source 2 is a laser diode element that emits near-infrared light with a wavelength of 905 nm in the above embodiment and the above embodiment, it is not necessarily limited to this. For example, a light source that emits near-infrared light with a wavelength of 750 to 1400 nm, a light source that emits infrared light with a wavelength of 1400 nm or more, a light source that emits visible light with a wavelength of 380 to 750 nm, or a light source that emits ultraviolet light with a wavelength of 380 nm or less is used. can be By forming the projection lenses 11, 31, 41, 51, 61 from a material having a refractive index of 1.56 or more at this wavelength, the projection lenses 11, 31, 41, 51, 61 can be miniaturized and widened. .

Further, the light source is not limited to a light source that emits light of a single wavelength, and a light source that emits light of a spectrum having a plurality of peak wavelengths, such as an LED light source, may be used. In this case, by forming the projection lenses 11, 31, 41, 51, 61 with a material having a refractive index of 1.56 or more at the peak wavelength with the highest intensity, the projection lenses 11, 31, 41, 51, 61 It is possible to widen the angle while downsizing. Further, depending on the type of light source, the light projecting device of the present invention may be used as a backlight of a display device or the like.

Note that, even with a light source other than a laser diode element, the light intensity of the light emitted from the light source is generally high at the central portion and low at portions away from the central portion. By aligning the center of the light with the Z-axis, the light intensity of the light projected from the light projecting device can be ensured over substantially the entire light projection range.

In the above embodiments, the incidence surfaces 12, 32, 42, 52, 62 are cylindrical surfaces and the exit surfaces 13, 33, 43, 53, 63 are cylindrical surfaces or toroidal surfaces. It is not limited. For example, the entrance surface may be a toroidal surface and the exit surface may be a cylindrical surface, or both the entrance surface and the exit surface may be toroidal surfaces. At least one of the entrance surface and the exit surface may be a free-form surface other than an anamorphic surface, or may be an axisymmetric surface with respect to the Z-axis.

2 Light source 10, 30, 40, 50, 60 Projection device 11, 31, 41, 51, 61 Projection lens 12, 32, 42, 52, 62 Incident surface 13, 33, 43, 53, 63 Output surface 15 th 1X refracted ray 16 1st X extension 17 2nd X refracted ray 18 2nd X extension 23 1st Y refracted ray 25 2nd Y refracted ray 26 2nd Y extension α5 1st X deflection angle α6 2nd X deflection angle β6 2nd Y deflection angle

Claims (10)

an incident surface on which light emitted from a light source is incident;
an emission surface on the opposite side of the incidence surface for emitting the light that has passed through the incidence surface to a light projection side,
When the optical axis that intersects the entrance surface and the exit surface is the Z axis, and the axes orthogonal to the Z axis and perpendicular to each other are the X axis and the Y axis,
the entrance surface and the exit surface are formed line-symmetrically with respect to the Z axis in the XZ cross section and the YZ cross section, respectively;
The incident surface in the XZ cross section is a concave curve on the light source side, and the absolute value of the curvature decreases as the distance from the Z axis increases,
the exit surface in the YZ cross section is a concave curve toward the light projection side;
In the XZ cross section, the absolute value of the curvature of the entrance surface at the intersection of the Z axis and the entrance surface is greater than the absolute value of the curvature of the exit surface at the intersection of the Z axis and the exit surface,
In the YZ cross section, the absolute value of the curvature of the incident surface at the intersection of the Z axis and the incident surface is smaller than the absolute value of the curvature of the exit surface at the intersection of the Z axis and the exit surface. projection lens. In the incident surface, the absolute value of the curvature of the XZ cross section at the intersection of the Z axis and the incident surface is larger than the absolute value of the curvature of the YZ cross section at the intersection of the Z axis and the incident surface,
The emission surface is characterized in that the absolute value of the curvature of the YZ section at the intersection of the Z axis and the emission surface is larger than the absolute value of the curvature of the XZ section at the intersection of the Z axis and the emission surface. Item 1. The projection lens according to Item 1. 3. The projection lens according to claim 1, wherein the entrance surface and the exit surface are anamorphic surfaces formed symmetrically with respect to the XZ section and the YZ section, respectively. one of the entrance surface and the exit surface is a cylindrical surface having a linear cross section perpendicular to either the X-axis direction or the Y-axis direction;
4. The projection lens according to claim 3, wherein the other of said entrance surface and said exit surface is a toroidal surface having curved cross sections perpendicular to both the X-axis direction and the Y-axis direction. 5. The projection according to any one of claims 1 to 4, wherein the exit surface in the XZ cross section is formed by a curved line that is concave in the vicinity of the Z axis and becomes convex at a position away from the Z axis. optical lens. 6. The projection lens according to claim 1, wherein the exit surface in the YZ cross section is a concave curve whose absolute value of curvature decreases with increasing distance from the Z axis. In the XZ cross section,
The light rays emitted from the light source include inner rays with a divergence angle greater than 0° and less than or equal to a half-value half-angle,
When the light source is placed at a position where the angle of incidence of the inner ray on the incident surface increases as the incident position of the inner ray on the incident surface moves away from the Z axis,
a first X refracted ray obtained by refracting the inner ray incident on the incident surface is located on the opposite side of the Z axis with respect to a first X extension line extending the inner ray;
a second X refracted ray obtained by refracting the first X refracted ray incident on the exit surface is positioned on the opposite side of the Z axis with respect to a second X extension line extending the first X refracted ray;
a first X deflection angle between the first X refracted ray and the first X extension line increases as the incident position of the inner ray on the incident surface moves away from the Z axis;
so that the second X deviation angle between the second X refracted ray and the second X extension line increases as the incident position of the first X refracted ray on the exit surface increases away from the Z axis,
7. The projection lens according to any one of claims 1 to 6, wherein the shapes of the entrance surface and the exit surface are set. In the YZ cross section,
the first Y-refracted ray is the ray that travels from the incident surface to the exit surface;
a second Y refracted ray obtained by refracting the first Y refracted ray incident on the exit surface is positioned on the opposite side of the Z axis with respect to a second Y extension line extending the first Y refracted ray;
The second Y deflection angle between the second Y refracted ray and the second Y extension line is such that the position of incidence of the first Y refracted ray on the exit surface increases as the position of incidence of the first Y refracted ray on the exit surface moves away from the Z axis.
8. The projection lens according to any one of claims 1 to 7, wherein the exit surface has a predetermined shape. 9. The projection lens according to claim 1, wherein the projection lens is made of a material having a refractive index of 1.56 or more at the wavelength of the light emitted from the light source. A light projecting device comprising a light source that emits light in the Z-axis direction and the projection lens according to any one of claims 1 to 9,
The light emitted from the light source has light intensity distributions in the XZ cross section and the YZ cross section that are symmetrical with respect to the Z axis, and the light intensity decreases as the distance from the Z axis increases, and the divergence angle in the XZ cross section is the divergence angle in the YZ cross section. A floodlight device characterized in that it is larger than

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