JP2005250394A - Illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminator using a light emitting element which restrains the heat generation of the light emitting element and radiates high-luminance and uniform light. <P>SOLUTION: The illuminator 21 is constituted of white LEDs 28, rods 29, a direction changing member 30 and a reflector 31. A plurality of white LEDs 28 are annularly provided by leaving space in between. The rods 29 are provided corresponding to a plurality of white LEDs 28 respectively, provided to extend toward a focal point 36 from the vicinity of the white LEDs 28, and formed to be a square pillar. The direction changing member 30 is provided at the position of the focal point 36 so as to change a light advancing direction. The reflection surface 31a of the reflector 31 is formed in parabolic shape. When the light is emitted from the white LED 28, parallel beams are radiated from the reflector 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lighting device.

  The illumination device is used in a liquid crystal projector, for example, and constitutes a part of an illumination optical system inside the liquid crystal projector. In addition to the illumination device, the illumination optical system includes an integrator lens, a polarization conversion element, and the like. This illumination optical system irradiates light onto a liquid crystal panel incorporated in the liquid crystal projector. The liquid crystal panel is preferably irradiated with bright and uniform light. For this purpose, it is desirable that the light emitted from the lighting device be uniform with high brightness. Conventionally, it has been common to use high-intensity discharge lamps such as ultra-high pressure mercury lamps, metal halide lamps, and xenon lamps as lighting devices.

  Recently, high-brightness LEDs have been developed, and it is considered promising to use LEDs in lighting devices. Compared with the high-intensity discharge lamp described above, the LED is advantageous in terms of small size and light weight, low voltage driving, response speed, and the like. On the other hand, there is a problem that it is difficult to obtain sufficient brightness with a single lamp. Patent Document 1 proposes an illumination device using LEDs arranged in an array. The light from the arrayed LED is incident on the rod lens and is irradiated as uniform light after repeated multiple reflection inside.

JP 2003-26295 A

  However, in the illumination device shown in Patent Document 1, since LEDs are arranged in an array, heat generation becomes a problem. The LED reduces brightness or accelerates deterioration due to heat generation.

  An object of the present invention is to provide an illuminating device using a light-emitting element that can suppress heat generation of the light-emitting element and can radiate high-luminance and uniform light.

  The present invention provides a plurality of light emitting elements arranged in an annular shape, and extends toward a predetermined position on the central axis of the ring, and is provided corresponding to each of the light emitting elements and transmits light. A rod made of a material and emitting light emitted from the light emitting element from one end face near the light emitting element and emitting the light from the other end face near the predetermined position; and a rod provided at the predetermined position and emitted from the rod. And a direction changing member that changes a traveling direction of the light, and a reflector that reflects the light from the direction changing member with the predetermined position as a focal position and irradiates the light to the outside. The material forming the rod is preferably formed of a material having a refractive index higher than that of air.

  In the vicinity of the light emitting element, a mirror that reflects light from the light emitting element and makes it incident on the one end face of the rod is preferably provided.

  The rod is preferably provided with an inclination so as to approach the bottom of the reflector as it extends toward the predetermined position.

  According to the present invention, a plurality of light emitting elements arranged in an annular shape, and extending toward a predetermined position on the central axis of the ring, provided corresponding to each of the light emitting elements, A rod that is formed of a transparent material and emits light emitted from the light emitting element from one end face near the light emitting element and emits the light from the other end face near the predetermined position; and a rod provided at the predetermined position from the rod Since it has a direction changing member that changes the traveling direction of the emitted light and a reflector that reflects the light from the direction changing member with the predetermined position as a focal position and irradiates the light to the outside, it is emitted from a plurality of light emitting elements. After being incident on the corresponding rod, the light is emitted from the rod toward the direction changing member. The traveling direction of the light is changed by the direction changing member, the light is reflected by the reflector, passes through a rod formed of a material that transmits light, and is irradiated to the outside. As described above, since the plurality of light emitting elements are arranged at intervals, heat generation can be suppressed. Further, since light from a plurality of light emitting elements can be irradiated, illumination with high luminance is obtained. Furthermore, since the direction changing member is located at the focal position of the reflector, the light emitted from the direction changing member and reflected by the reflector is uniform. In particular, if the reflecting surface of the reflector has a parabolic shape, the irradiated light becomes parallel light, and if the reflecting surface of the reflector has an elliptical shape, the irradiated light becomes convergent light.

  If a mirror that reflects light from the light emitting element and makes it incident on the one end surface of the rod is provided in the vicinity of the light emitting element, the irradiation part of the light emitting element is directed to the mirror, and the fixing part of the light emitting element is Since it can arrange | position on the plane orthogonal to the center axis | shaft of a ring, a some light emitting element can be arranged in a circle | round | yen, and can be provided in the board | substrate orthogonal to the center axis | shaft of the said ring. Thereby, manufacture becomes easy.

  Since the rod is provided with an inclination so as to approach the bottom of the reflector as it extends toward the predetermined position, the reflector having the predetermined position as a focal position can be easily formed in an elliptical shape. If the reflector is formed in an elliptical shape, light reflected from the reflector becomes convergent light.

  As shown in FIG. 1, the liquid crystal projector 2 includes an illumination optical system 3, mirrors 4 and 5, a dichroic mirror 6, a liquid crystal panel 7, a dichroic prism 8, and a projection lens 9.

  The illumination optical system 3 includes an illumination device 21, an integrator lens 22, and a polarization conversion optical system 23. The illumination device 21, which will be described in detail later, irradiates with high brightness and uniform white parallel light. The integrator lens 22 further uniformizes this light. The polarization conversion optical system 23 aligns the polarization direction of light.

  The light that has been made uniform and whose polarization direction is aligned is separated into light of three colors R, G, and B by the dichroic mirror 6 through the mirror 4. These three color lights are applied to the liquid crystal panel 7 corresponding to each color. The liquid crystal panel 7 is made of an element in which a liquid crystal and a polarizing film are sandwiched between two transparent plates, and the transmittance for each pixel is changed by changing the polarization direction of linearly polarized light. The three color lights transmitted through the respective liquid crystal panels 7 are combined by the dichroic prism 8 and projected onto the screen 24 provided outside via the projection lens 9.

  As shown in FIG. 2, the illumination device 21 of the illumination optical system 3 includes a plurality of white LEDs 28, a plurality of rods 29, a direction changing member 30, and a reflector 31.

  The white LED 28 has a bottom portion 28a fixed inside a cylindrical mounting member 35 (see FIG. 3), and is provided at a predetermined interval. A plurality of white LEDs 28 are provided in an annular shape. The irradiation part 28b of the white LED 28 faces the center point of the ring. The center point of the ring coincides with the focal point 36 (see FIG. 3) of the reflecting surface 31a of the reflector 31. Reference numeral 37 denotes a central axis of the ring.

  The rod 29 is prepared corresponding to each of the plurality of white LEDs 28. The rod 29 is formed in a quadrangular prism and is provided so as to extend from the vicinity of the white LED 28 toward the focal point 36. The rod 29 is tapered in the circumferential direction of the central axis 37, and the cross-sectional area of the rod 29 decreases as the rod 29 moves toward the focal point 36. The rod 29 is made of a material having a refractive index larger than that of air. The rod 29 receives light from the white LED 28 on one end surface 29 a in the vicinity of the white LED 28 and emits the light from the other end surface 29 b in the vicinity of the focal point 36. An antireflection film (not shown) is attached to the inner surface 29c (see FIG. 3) of the rod 29 facing the reflecting surface 31a of the reflector 31. Reference numeral 29 d indicates the outer surface of the rod 29. Although not shown, an air gap is formed between the rods 29.

  As shown in FIG. 3, the direction changing member 30 is provided at the focal point 36 position. The direction changing member 30 is a lens that changes the traveling direction of light. The direction changing member 30 irradiates the light emitted from the other end surface 29 b of the rod 29 toward the reflecting surface 31 a of the reflector 31. The direction changing member 30 only needs to change the traveling direction of light. For example, the direction changing member 30 may be a hemispherical mirror having a reflective outer surface, or may be a known member. The reflector 31 is provided so as to surround the direction changing member 30 and the rod 29. The reflector 31 has a parabolic shape on the reflecting surface 31a.

  Hereinafter, the operation of the above configuration will be described with reference to FIG. 3 focusing on the operation of the illumination device 21 of the illumination optical system. When the white LED 28 is turned on, white light is emitted, and the light enters the rod 29 from one end surface 29 a of the rod 29. The light repeats total reflection on the inner surface of the rod 29 and exits from the other end surface 29b. Light is emitted almost uniformly from the other end surface 29 b of the rod 29. The emitted light has its traveling direction changed by the direction changing member 30 and is incident on the reflecting surface 31 a of the reflector 31 almost uniformly. Here, the direction changing member 30 can be considered as a pseudo point light source.

  The light incident on the reflector 31 is reflected by the parabolic reflecting surface 31a to become parallel light. The reflected parallel light is incident on the rod 29 from the inner surface 29 c of the rod 29, and then is irradiated to the outside from the outer surface 29 d of the rod 29. Here, since the light incident on the rod 29 enters the outer surface 29d from the inside of the rod 29 at a substantially right angle, the light can enter the outer surface 29d at an angle larger than the critical angle, and no reflection occurs on the outer surface 29d.

  Thus, since the light from the plurality of white LEDs 28 can be used, the illumination device 21 can perform illumination with high luminance. Further, the illumination from the illumination device 21 is substantially uniform. Furthermore, since the plurality of white LEDs 28 are arranged at intervals, heat generation can be suppressed. As a result, the white LED 28 can be prevented from lowering brightness or deteriorating due to heat generation.

  The light emitted from the illuminating device 21 is incident on the integrator lens 22 and then irradiated on the liquid crystal panel 7 through the polarization conversion optical system 23, the dichroic mirror 6, and the like.

  In the above embodiment, the white LED 28 is arranged so that the irradiation portion 28b faces the one end surface 29a of the rod 29. However, as shown in FIG. 4, the irradiation portion 28b faces the light irradiation direction to the outside. In this way, the white LED 28 may be disposed in the vicinity of the one end surface 29 a of the rod 29. In this case, a mirror 40 that reflects white light emitted from the white LED 28 and enters the one end surface 29 a of the rod 29 is provided. Further, the bottom portion 28 a of the white LED 28 is fixed to a substrate 41 formed in a donut shape outside the reflector 31. Thereby, the plurality of white LEDs 28 can be easily attached to one substrate 41.

  In the above embodiment, the extending direction of the rod 29 and the central axis 37 are orthogonal to each other, and the intersection is the focal point 36 of the reflector 31 having the parabolic reflecting surface 31a. The direction in which the rod 29 extends and the central axis 37 may intersect at a predetermined angle that is not a right angle, and as shown in FIG. 5, a reflector 45 having an ellipsoidal reflecting surface 45a with the intersection 46 as a focal point 46 may be provided. The rod 29 extends toward the focal point 46 and is disposed so as to approach the bottom 45b of the reflector 45 as the focal point 46 is approached. Note that the bottom 45b indicates the peripheral area of the intersection of the central axis 37 and the reflection surface 45a in the reflection surface 45a. If the rod 29 is arranged in this way, the reflecting surface 45a of the reflector 45 can be deepened, and the degree of freedom in designing the reflector shape is increased. That is, since the outer diameter can be increased even at the same focal length, more white LEDs 28 can be arranged. Moreover, since more reflected light by the direction change member 30 can be taken in, the utilization efficiency of light can be increased. By appropriately selecting the shape of the rod and the shape of the reflecting surface of the reflector, it is possible to radiate parallel light or convergent light to the outside.

  In the above embodiment, the rod 29 is tapered only in the circumferential direction of the central axis 37, but further, the area of the other end surface (outgoing surface) of the rod is also tapered by tapering in the central axis 37 direction. A light source closer to a point light source can be obtained by reducing the size and the direction changing member. Thereby, the utilization efficiency of light by the subsequent integrator can be increased.

  In the above embodiment, the rod 29 is formed in the shape of a quadrangular prism. However, the rod 29 is not limited to this shape as long as it emits light from the white LED incident from one end face almost uniformly from the other end face. .

  In the above embodiment, the illumination device 21 of the present invention is used for the liquid crystal projector 2, but may be used for other devices.

It is the schematic of a liquid crystal projector. It is an external appearance perspective view of an illuminating device. It is explanatory drawing of an illuminating device. It is explanatory drawing of the illuminating device at the time of providing a mirror in the vicinity of white LED. It is explanatory drawing of the illuminating device at the time of providing a rod in cone shape.

Explanation of symbols

2 Liquid Crystal Projector 3 Illumination Optical System 21 Illumination Device 22 Integrator Lens 23 Polarization Conversion Optical System 28 White LED (Light Emitting Element)
28a Bottom portion 28b Irradiation portion 29 Rod 29a One end surface 29b Other end surface 29c Inner surface 30 Direction changing member 31 Reflector 31a Reflecting surface 36 Focus 37 Central axis 40 Mirror 41 Substrate 45 Reflector 45a Reflecting surface 45b Bottom 46 Focus

Claims (3)

A plurality of light emitting elements arranged in an annular shape;
Extending toward a predetermined position on the central axis of the ring and provided corresponding to each of the light emitting elements, formed of a material that transmits light, and emits light emitted from the light emitting element in the vicinity of the light emitting element. A rod that is incident from the end face and emits the light from the other end face in the vicinity of the predetermined position;
A direction changing member that changes a traveling direction of light emitted from the rod provided at the predetermined position;
An illuminating apparatus comprising: a reflector that reflects the light from the direction changing member with the predetermined position as a focal position and irradiates the light to the outside.   The illumination device according to claim 1, wherein a mirror that reflects light from the light emitting element and makes it incident on the one end surface of the rod is provided in the vicinity of the light emitting element. The lighting device according to claim 1, wherein the rod is provided with an inclination so as to approach the bottom of the reflector as it extends toward the predetermined position.

Images