JP5000403B2 - Magnification optical system and imaging device - Google Patents

Description

  The present invention relates to a variable power optical system and an image pickup apparatus that are suitably used for small devices having an image pickup function, in particular, digital still cameras, camera-equipped mobile phones, and personal digital assistants (PDAs).

  In recent years, in an imaging apparatus such as a digital still camera, as the imaging element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) has been miniaturized, further miniaturization of the entire apparatus is required. Accordingly, a photographic lens, particularly a variable magnification optical system (zoom lens) is required to be thinned by shortening the entire length or the like. Conventionally, as a variable power optical system used for a digital still camera or the like, for example, a five-group configuration as a whole as disclosed in Patent Document 1 is known. The zoom optical system described in Patent Document 1 is a so-called straight type optical system in which optical members constituting a lens system are linearly arranged in one direction without changing the direction of the optical axis. Here, the size of the imaging device in the thickness direction is substantially determined by the length from the most object-side optical member to the imaging device. On the other hand, the number of lenses has increased in order to satisfy recent demands for higher pixel and higher performance imaging devices, and it has become difficult to shorten the overall length of the lens system. For this reason, it has become difficult to achieve a reduction in the thickness of the entire imaging apparatus. In order to reduce the thickness of the imaging apparatus, a so-called bending optical system has been developed in which the optical path of the lens system is bent halfway.

In the bending optical system, a reflecting member such as a right-angle prism is disposed in the first lens group, and the length of the optical system in the thickness direction is shortened by bending the optical path approximately 90 ° in the middle. As such a variable magnification optical system of the bent type, an optical system having a four-group configuration as a whole and moving the second lens group and the fourth lens group at the time of zooming is known. In recent years, since there is a demand for a higher zoom ratio, a variable magnification optical system of a bent type, which has a five-group configuration as a whole and has a higher zoom ratio than a four-group configuration. Have been developed (see Patent Documents 2 to 4). The zoom optical system described in Patent Document 3 moves only the second lens group and the fourth lens group at the time of zooming. In the zoom optical system described in Patent Documents 2 and 4, In addition to the group and the fourth lens group, the fifth lens group is also moved during zooming. In the variable magnification optical system described in Patent Document 2, the fifth lens group has a focusing function, and focusing from infinity to a short distance is performed by moving the fifth lens group to the image plane side. At the time of zooming, the focal length is changed by the linear operation of the second lens group and the fourth lens group, and the image plane variation is corrected by the non-linear operation of the fifth lens group.
Japanese Patent No. 3196283 JP 2006-301543 A JP 2006-323051 A JP 2006-98686 A

  However, the optical system described in Patent Document 1 is disadvantageous for miniaturization because the focal length f1 of the first lens group is long and the total lens length is long. In addition, since the optical system described in Patent Document 2 is a system that performs focusing by moving the fifth lens group to the image plane side, when the fifth lens group is moved at the time of focusing, fluctuations in the exit pupil distance are caused. And shading changes are likely to occur. In addition, since the fifth lens group approaches the image plane when focused, there is a problem that dust and scratches attached to the lens surface of the fifth lens group easily affect the image quality. In the optical system described in Patent Document 3, when the first lens group is divided into the front group and the rear group from the reflecting surface, the focal length f1r of the rear group in the first lens group is set to be long. For this reason, the total lens length becomes long, which is disadvantageous for downsizing. In the optical system described in Patent Document 4, since the focal length f2 of the second lens group is set to be long, the total length of the lens becomes long, which is disadvantageous for downsizing.

  The present invention has been made in view of such problems, and an object thereof is to provide a variable magnification optical system and an imaging apparatus that can achieve a reduction in size while reducing the overall lens length while maintaining good optical performance. There is to do.

The zoom lens system according to onset Ming, in order from the object side, a first lens unit having a positive refractive power fixed during zooming and focusing, the negative refractive power and moves during zooming A second lens group, a third lens group having a positive refractive power that is fixed during zooming and focusing, and a fourth lens group having a positive refractive power that moves during zooming and has a focusing function; A fifth lens unit having a negative refractive power that moves during zooming, and the first lens unit includes, in order from the object side, a front group having a negative refractive power, a reflecting member that bends the optical path, and a positive It is comprised by the rear group which has refractive power, and is comprised so that the following conditional expressions may be satisfied. In the formula, f1f represents the focal length of the front group in the first lens group, and f1r represents the focal length of the rear group in the first lens group.
−3.5 <f1f / f1r <−1.8 ( 1 )
Moreover, it is preferable to be configured so as to satisfy the following conditional expression. In the equation, fw is the focal length of the entire system at the wide-angle end, f2 is the focal length of the second lens group, and f1 is the focal length of the first lens group .
0.5 <| f2 / fw | <0.8 (2)
0.4 <fw / f1 <0.8 (3)

In the zoom lens system according to onset bright, generally at 5-group configuration, the second lens group during zooming, by a method of moving the fourth lens group and the fifth lens group, the high zoom ratio It will be advantageous. In addition, since the optical path is bent by the reflecting member disposed in the first lens group, the length in the thickness direction of the optical system is suppressed while maintaining good optical performance. Therefore, it is easy to reduce the thickness when incorporated in an imaging apparatus. When the bending optical system is incorporated in an image pickup apparatus, the thickness of the bending optical system largely depends on the size of the first lens group, which is a portion that bends the optical path, rather than the total length of the lens. Satisfying the conditional expression ( 1 ) makes it easy to reduce the overall length and reduce the size of the first lens group including the reflecting member. In addition, since the fourth lens group has a focusing function, the variation in the exit pupil distance is less during focusing and the shading change is smaller than when the fifth lens group has a focusing function. Less. Furthermore, dust and scratches attached to the lens surface of the fifth lens group G5 closest to the image plane at the time of focusing are less likely to affect the image quality.

In the zoom lens system according to onset Ming, during zooming, the second lens group and the fifth lens group, at different movement direction on the optical axis, and move together to the linear linear motion, The fourth lens group may move so as to make a non-linear motion.
As a result, when the second lens group and the fifth lens group are moved, they can be moved by a single motor, and the number of motors originally required for each moving lens group and the simplification of movement control are achieved. This makes it possible to reduce the size and cost of the photographing apparatus including the mechanism.

Further, in the zoom lens system according to onset bright, while each lens group of the first to fifth lens group may include at least one plastic lens. This is advantageous for reducing the weight and cost of the optical system.

Further, in the zoom lens system according to onset bright, when the first lens group has at least one positive lens in the rear group, the second lens group has at least one negative lens Preferably, a plastic lens is used for at least one positive lens in the rear group in the first lens group, and a plastic lens is used for at least one negative lens in the second lens group. Thereby, the focal movement at the time of temperature change by using a plastic lens is reduced.

Imaging apparatus according to the present invention, a zoom lens system according to onset bright, in which an imaging device that outputs an imaging signal corresponding to an optical image formed by the variable power optical system.
In the imaging device according to the present invention, a high-resolution imaging signal is obtained based on the high-resolution optical image obtained by the variable power optical system of the present invention.

According to the variable-power optical system according to the present onset bright, generally at 5-group configuration, the second lens group during zooming, the fourth lens group and the fifth lens group and a method of moving, and the first lens group The optical path is bent by the reflecting member placed on the lens, and the appropriate conditions are satisfied with respect to the focal lengths of the front group and the rear group in the first lens group, so that good optical performance is maintained. However, it is possible to reduce the overall length of the lens and reduce the size.

  In addition, according to the imaging apparatus of the present invention, since an imaging signal corresponding to the optical image formed by the high-performance variable magnification optical system of the present invention is output, a high-resolution imaging signal can be obtained. Can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B show a first configuration example of a variable magnification optical system according to an embodiment of the present invention. This configuration example corresponds to a lens configuration of a first numerical example (FIGS. 9A, 9B, and 10) described later. 1A corresponds to the optical system arrangement at the wide-angle end (shortest focal length state), and FIG. 1B corresponds to the optical system arrangement at the telephoto end (longest focal length state). Similarly, cross-sectional configurations of second to seventh configuration examples corresponding to lens configurations of second to seventh numerical examples to be described later are shown in FIGS. 2 (A), (B) to FIG. 7 (A), Shown in (B). In FIGS. 1A and 1B to FIGS. 7A and 7B, the symbol Ri increases sequentially toward the image side (imaging side), with the surface of the component closest to the object side being the first. In this way, the radius of curvature of the i-th surface that is labeled is shown. The symbol Di indicates the surface interval on the optical axis Z1 between the i-th surface and the i + 1-th surface. In addition, about the code | symbol Di, the code | symbol is attached | subjected only to the surface intervals D8, D13, D16, D21, and D23 of the part which changes with scaling. Since the basic configuration is the same for each configuration example, the following description is based on the first configuration example shown in FIGS. 1 (A) and 1 (B).

  This variable magnification optical system is used by being mounted on a small device having an imaging function, such as a digital still camera, a mobile phone with a camera, and a PDA. This variable magnification optical system has a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power in order from the object side along the optical axis Z1. It includes a third lens group G3, an aperture stop St for adjusting the amount of light, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power.

  An imaging device 100 such as a CCD is disposed on the imaging surface of the variable magnification optical system. At least the zoom optical system and the image sensor 100 constitute an image pickup apparatus according to the present invention. Various optical members GC may be arranged between the fifth lens group G5 and the image sensor 100 according to the configuration on the camera side where the lens is mounted. For example, a flat optical member such as a cover glass for protecting the imaging surface or an infrared cut filter may be disposed.

  This zoom optical system is always fixed when the first lens group G1 and the third lens group G3 are zoomed and focused, and the second lens group G2, the fourth lens group G4, and the fifth lens are fixed at the time of zooming. The group G5 moves on the optical axis Z1. The fourth lens group G4 has a focusing function, and the fourth lens group G4 moves on the optical axis Z1 not only at the time of zooming but also at the time of focusing. As this zooming optical system zooms from the wide-angle end to the telephoto end, each moving group moves from the state shown in FIG. 1A to the state shown in FIG. Move like drawing. In this case, the second lens group G2 and the fifth lens group G5 move on the optical axis Z1 in different moving directions and so as to perform linear linear motions together. The fourth lens group G4 moves so as to make a non-linear motion. The second lens group G2 and the fifth lens group G5 are mainly responsible for the zooming action, and the fourth lens group G4 is responsible for correcting the image plane variation accompanying the zooming.

  The first lens group G1 includes, in order from the object side, a front group G1f having a negative refractive power, a reflecting member G1p that bends the optical path, and a rear group G1r having a positive refractive power. The front group G1f includes, for example, one negative lens L11. The rear group G1r includes, for example, two positive lenses L12 and L13. The reflecting member G1p is configured by, for example, a right-angle prism LP having an internal reflection surface that bends the optical path by approximately 90 °.

  For example, the second lens group G2 includes, in order from the object side, a single negative lens L21 and a cemented lens including a negative lens L22 and a positive lens L23. The third lens group G3 is composed of, for example, one positive lens L31. For example, the fourth lens group G4 includes, in order from the object side, a cemented lens including two lenses L41 and L42 and a positive lens L43 having a convex surface facing the object side. For example, the fifth lens group G5 includes one negative lens L51.

This variable magnification optical system satisfies the following conditional expression (1 ) . In the formula, f1f represents the focal length of the front group G1f in the first lens group G1, and f1r represents the rear group G1r in the first lens group G1 .
−3.5 <f1f / f1r <−1.8 (1)

This zoom optical system preferably satisfies the following conditional expressions (2) and (3). In the equation, fw is the focal length of the entire system at the wide-angle end, f2 is the focal length of the second lens group G2, and f1 is the focal length of the first lens group G1 .
0.5 <| f2 / fw | <0.8 (2)
0.4 <fw / f1 <0.8 (3)

  FIG. 8 shows a configuration example of a lens moving mechanism in the variable magnification optical system. FIG. 8 shows a configuration of the variable magnification optical system as viewed from the front side (light incident side). This lens moving mechanism includes a linear moving mechanism that moves the second lens group G2 and the fifth lens group G5, and a non-linear moving mechanism that moves the fourth lens group G4 non-linearly.

  The nonlinear moving mechanism includes a single motor M2, a shaft 20 connected to the motor M2, and a transmission block 21 screwed to the shaft 20. The shaft 20 is formed with a male screw. When the shaft 20 rotates with the rotation of the motor M2, the transmission block 21 screwed into the shaft 20 moves linearly. A lens drive control unit (not shown) nonlinearly moves the fourth lens group G4 by controlling the amount of rotation of the motor M2.

  The linear movement mechanism includes a single motor M1, a shaft 10 connected to the motor M1, and two transmission blocks 11 and 12 screwed to the shaft 10. The motor M1 is driven in accordance with an instruction from a lens drive control unit (not shown) and supplies the rotational force to the shaft 10. The shaft 10 is arranged in parallel with the optical axis after being reflected by the right-angle prism LP, and a first male screw 10A is provided in the moving range of the fifth lens group G5 in a portion corresponding to the moving range of the second lens group G2. A second male screw 10B is formed in the corresponding part.

  The first male screw 10A and the second male screw 10B have opposite winding directions. That is, if the first male screw 10A is a right screw, the second male screw 10B is a left screw. Further, the lead amounts of the first male screw 10A and the second male screw 10B are also different. Therefore, the amount of advancement of the first male screw 10A and the amount of advancement of the second male screw 10B differ when the shaft 10 is rotated once. The first transmission block 11 is screwed to the first male screw 10A, and the second transmission block 12 is screwed to the second male screw 10B. The first transmission block 11 is physically connected to the second lens group G2, and the second transmission block 12 is physically connected to the fifth lens group G5. As a result, when the shaft 10 rotates by driving the motor M1, the first transmission block 11 and the second transmission block 12 are linearly driven. At this time, the first male screw 10A and the second male screw 10B are opposite in the winding direction, so that the first transmission block 11 and the second transmission block 12 screwed together are in opposite directions. Moving. The second lens group G2 and the fifth lens group G5 that are physically connected to the first transmission block 11 and the second transmission block 12 also move in directions opposite to each other. Further, since the first male screw 10A and the second male screw 10B have different lead amounts, the movement amounts of the first transmission block 11 and the second transmission block 12 are also different from each other. As a result, the second lens group G2 and the second male screw 10B The amount of movement of the five lens group G5 is also different. As a result, the second lens group G2 and the fifth lens group G5 can be linearly moved in a desired direction with a desired amount of movement only by driving a single motor M1.

  In this lens moving mechanism, the focal length changing operation of the second lens group G2 and the fifth lens group G5 and the image plane position correcting operation of the fourth lens group G4 at the time of zooming are separated. Thereby, the moving mechanism of the 2nd lens group G2 and the 5th lens group G5 can be simplified, As a result, cost reduction and space saving can be achieved. The linear movement mechanism in FIG. 8 is an example, and other forms may be used as long as the second lens group G2 and the fifth lens group G5 can be linearly moved. For example, in the above-described example, a transmission mechanism having the shaft 10 and the transmission blocks 11 and 12 is used, but the two driving lenses are driven by a single motor M1 as linear motions having different movement directions and movement amounts. Other transmission mechanisms may be used as long as they can transmit to the groups G2 and G5 at the same time. For example, a transmission mechanism having two types of pinions having different pitches and both connected to the rotating shaft of the motor and two types of racks engaged with the two types of pinions may be used.

Next, operations and effects of the variable magnification optical system configured as described above will be described.
This zoom optical system has a five-group configuration as a whole, and is advantageous in increasing the zoom ratio by moving the second lens group G2, the fourth lens group G4, and the fifth lens group G5 during zooming. By satisfying the appropriate conditional expressions ( 3 ) and (2) regarding the focal lengths of the first lens group G1 and the second lens group G2, the total lens length is shortened while maintaining good optical performance. Thus, downsizing becomes easy.

Conditional expression ( 3 ) is an expression relating to the focal length f1 of the first lens group G1, and by satisfying this expression, the optical system can be miniaturized and aberrations in the entire zooming range can be corrected well. If the lower limit of conditional expression ( 3 ) is not reached, the refractive power of the first lens group G1 becomes small, so that the total lens length becomes long, and the outer diameter of the first lens group G1 including the reflecting member G1p is also enlarged. Miniaturization of the optical system cannot be achieved. If the value exceeds the upper limit, the refractive power of the first lens group G1 becomes strong, which is advantageous for downsizing the optical system. However, since the aberration generated in the first lens group G1 is increased, the entire zooming range is increased. It becomes difficult to correct aberrations satisfactorily.

  Conditional expression (2) is an expression relating to the focal length f2 of the second lens group G2. By satisfying this expression, the optical system can be miniaturized and aberrations in the entire zooming range can be corrected well. If the lower limit of conditional expression (2) is not reached, the refractive power of the second lens group G2 increases, which is advantageous for downsizing, but the aberration generated in the second lens group G2 increases, and aberrations in the entire zoom range. Is difficult to correct well. If the upper limit is exceeded, the refractive power of the second lens group G2 will be reduced and the aberration generated in the second lens group G2 will be reduced, but the overall length of the lens will be increased and miniaturization cannot be achieved.

  In this variable magnification optical system, the object light incident on the first lens group G1 is bent by approximately 90 ° toward the second lens group G2 by the internal reflection surface of the right-angle prism LP, and is incident on the incident surface of the first lens group G1. An image is formed on the image sensor 100 arranged to be orthogonal. By adopting such a bending optical system configuration, it is possible to suppress the length of the optical system in the thickness direction while maintaining good optical performance, and achieve thinning when incorporated in an imaging device. It becomes possible to do. In such a bending optical system, the first lens group G1 is composed of, in order from the object side, a front group G1f having a negative refractive power, a reflecting member G1p that bends the optical path, and a rear group G1r having a positive refractive power. By disposing the front group G1f having negative refractive power in front of the reflecting member G1p, the reflecting member G1p can be reduced in size and the optical system can be reduced in thickness.

Conditional expression ( 1 ) is an expression relating to the focal lengths f1f and f1r between the front group G1f having negative refractive power and the rear group G1r having positive refractive power in the first lens group G1, and satisfies this expression. Thus, it is possible to reduce the outer diameter of the first lens group G1 including the reflecting member G1p and shorten the overall lens length. If the lower limit of conditional expression ( 1 ) is not reached, the refractive power of the front group G1f in the first lens group G1 decreases, and the diameter of the light beam passing through the reflecting member G1p increases, so the first lens including the reflecting member G1p. The outer diameter of group G1 will become large. If the upper limit is exceeded, the refractive power of the rear group G1r in the first lens group G1 becomes small, and the total lens length becomes long.

  Furthermore, in this zoom optical system, when the second lens group G2 and the fifth lens group G5 are moved during zooming, both the second lens group G2 and the second lens group G2, When the fifth lens group G5 is moved, it can be moved by a single motor M1 as shown in FIG. As a result, the reduction in the number of motors originally required for each moving lens group and the simplification of the movement control can be achieved, whereby the downsizing and cost reduction of the photographing apparatus including the mechanism can be achieved. Further, by moving the fourth lens group G4 at the time of focusing, the variation of the exit pupil distance is small even at the time of focusing, and the change in shading can be reduced. Furthermore, dust and scratches attached to the lens surface of the fifth lens group G5 are less likely to affect the image quality as compared with the method of moving the fifth lens group G5 closest to the image plane during focusing.

  In the zoom optical system, at least one plastic lens may be included in each of the first to fifth lens groups G1 to G5. As a result, the weight and cost of the optical system can be reduced. In this case, it is preferable that a plastic lens is used for at least one positive lens in the rear group G1r in the first lens group G1, and a plastic lens is used for at least one negative lens in the second lens group G2. The plastic lens has a larger refractive index change and expansion coefficient than the glass lens when the temperature changes. Therefore, if a lot of plastic lenses are used, the focal point shift when the temperature changes increases, but at least one of the rear group G1r in the first lens group G1. By using a plastic lens as one positive lens and using a plastic lens as at least one negative lens in the second lens group G2, it is possible to reduce the focal shift when the temperature changes.

  As described above, according to the variable magnification optical system according to the present embodiment, it is possible to achieve a miniaturized optical system by shortening the entire lens length while maintaining good optical performance. In addition, according to the imaging apparatus according to the present embodiment, since an imaging signal corresponding to the optical image formed by the high-performance variable magnification optical system according to the present embodiment is output, high resolution is achieved. An imaging signal can be obtained.

  Next, specific numerical examples of the variable magnification optical system according to the present embodiment will be described. Hereinafter, the first to seventh numerical examples will be described together.

  FIGS. 9A, 9B and 10 show specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 1A and 1B. In particular, FIG. 9A shows the basic lens data, and FIGS. 9B and 10 show other data. In the field of the surface number Si in the lens data shown in FIG. 9A, in the variable magnification optical system according to Example 1, the surface of the component closest to the object side is the first, and sequentially increases toward the image side. The number of the i-th surface (i = 1 to 25) with the reference numerals attached is shown. In the column of the curvature radius Ri, the value (mm) of the curvature radius of the i-th surface from the object side is shown in correspondence with the reference symbol Ri in FIG. Similarly, the column of the surface interval Di indicates the interval (mm) on the optical axis between the i-th surface Si and the i + 1-th surface Si + 1 from the object side. The column of Ndi shows the value of the refractive index for the d-line (587.6 nm) between the i-th surface Si and the i + 1-th surface Si + 1 from the object side. The column of νdj shows the Abbe number value for the d-line of the j-th optical element from the object side. FIG. 8A also shows various data of the paraxial focal length f (mm), F number (FNO.), And field angle 2ω (ω: half field angle) of the entire system at the wide angle end and the telephoto end. The values are also shown.

  In the variable magnification optical system according to Example 1, the second lens group G2, the fourth lens group G4, and the fifth lens group G5 move on the optical axis as the magnification changes. The values of the surface intervals D8, D13, D16, D21, and D23 are variable. FIG. 9B shows values at the wide-angle end and the telephoto end as data at the time of zooming of these surface intervals D8, D13, D16, D21, and D23.

  In the lens data of FIG. 9A, the symbol “*” attached to the left side of the surface number indicates that the lens surface has an aspherical shape. The variable magnification optical system according to Example 1 includes both surfaces S7 and S8 of the lens L13 in the first lens group G1, both surfaces S14 and S15 of the lens L31 in the third lens group G3, and a lens L43 in the fourth lens group G4. Both surfaces S20 and S21 are aspherical. The basic lens data in FIG. 9A shows the numerical values of the curvature radii near the optical axis as the curvature radii of these aspheric surfaces.

FIG. 10 shows aspherical data in the variable magnification optical system according to the first example. In the numerical values shown as aspherical data, the symbol “E” indicates that the subsequent numerical value is a “power exponent” with a base of 10, and the numerical value represented by an exponential function with the base of 10 is Indicates that the value before “E” is multiplied. For example, “1.0E-02” indicates “1.0 × 10 ⁻² ”.

As the aspherical data of the variable magnification optical system according to Example 1, the values of the coefficients _An and K in the aspherical shape expression represented by the following expression (A) are described. More specifically, Z is the length (mm) of a perpendicular line drawn from a point on the aspheric surface at a height Y from the optical axis to the tangential plane (plane perpendicular to the optical axis) of the apex of the aspheric surface. Show.
Example variable magnification optical system according to 1 are represented appropriately effectively using order of up to A ₃ to A ₂₀ as aspherical coefficients A _n.
Z = C · Y ² / {1+ (1−K · C ² · Y ² ) ^1/2 } + ΣA _n · Y ⁿ (A)
(N = an integer greater than 3)
However,
Z: Depth of aspheric surface (mm)
Y: Distance from the optical axis to the lens surface (height) (mm)
K: eccentricity C: paraxial curvature = 1 / R
(R: paraxial radius of curvature)
A _n : nth-order aspheric coefficient

  In the same manner as the variable magnification optical system according to the first embodiment, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. (A), FIG. 11 (B) and FIG. Similarly, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 3A and 3B is set as Example 3, and FIGS. 13A, 13B, and FIG. 14 shows. Similarly, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 4A and 4B is taken as Example 4, and FIGS. 15A, 15B, and FIG. 16 shows. Similarly, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 5A and 5B is taken as Example 5, and FIGS. 17A, 17B, and FIG. 18 shows. Similarly, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 6A and 6B is taken as Example 6, and FIGS. 19A, 19B, and FIG. 20 shows. Similarly, specific lens data corresponding to the configuration of the variable magnification optical system shown in FIGS. 7A and 7B is taken as Example 7, and FIGS. 21A, 21B, and FIG. 22 shows.

  In any of the variable magnification optical systems of Examples 2 to 6, similarly to the variable magnification optical system according to Example 1, both surfaces S7 and S8 of the lens L13 in the first lens group G1 and the third lens group G3 are used. Both surfaces S14 and S15 of the lens L31 and both surfaces S20 and S21 of the lens L43 in the fourth lens group G4 are aspherical.

  Similarly to the variable magnification optical system according to Example 1, the variable magnification optical system according to Example 7 includes both surfaces S7 and S8 of the lens L13 in the first lens group G1, and both surfaces S14 of the lens L31 in the third lens group G3. , S15 and both surfaces S20, S21 of the lens L43 in the fourth lens group G4 are all aspherical. Furthermore, in the variable magnification optical system of Example 7, both surfaces S9 and S10 of the lens L21 in the second lens group G2 are aspherical in addition to them. In the variable magnification optical system of Example 7, one plastic lens is included in each of the first to fifth lens groups G1 to G5. Specifically, the positive lens L13 in the rear group G1r of the first lens group G1, the negative lens L21 in the second lens group G2, the positive lens L31 in the third lens group G3, and the fourth lens group G4. Plastic lenses are used for the positive lens L43 in the middle and the negative lens L51 in the fifth lens group G5.

  FIG. 23 shows a summary of values relating to the above-described conditional expressions for the respective examples. As can be seen from FIG. 23, the value of each example is within the numerical range of each conditional expression.

  24A to 24D show spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration at the wide angle end in the variable magnification optical system according to Example 1, respectively. FIGS. 25A to 25D show similar aberrations at the telephoto end. Each aberration diagram shows an aberration with the d-line (587.6 nm) as a reference wavelength. The spherical aberration diagram and the lateral chromatic aberration diagram also show aberrations at wavelengths of 460 nm and 615 nm. In the astigmatism diagram, the solid line indicates the sagittal direction and the broken line indicates the tangential direction. FNO. Indicates an F value, and ω indicates a half angle of view.

  Similarly, various aberrations of the variable magnification optical system according to Example 2 are shown in FIGS. 26 (A) to 26 (D) (wide angle end) and FIGS. 27 (A) to 27 (D) (telephoto end). Show. Similarly, various aberrations of the variable magnification optical system according to Example 3 are shown in FIGS. 28A to 28D (wide-angle end) and FIGS. 29A to 29D (telephoto end). FIGS. 30A to 30D (wide angle end) and FIGS. 31A to 31D (telephoto end) are shown in FIG. FIG. 32A to FIG. 32D (wide angle end) and FIG. 33A to FIG. 33D (telephoto end) are shown in FIG. Various aberrations regarding the variable magnification optical system are shown in FIGS. 34 (A) to 34 (D) (wide-angle end) and FIGS. 35 (A) to 35 (D) (telephoto end). In addition, various aberrations of the variable magnification optical system according to Example 7 are shown in FIGS. 36A to 36D (wide-angle end) and FIGS. 37A to 37D (telephoto end).

  As can be seen from the above numerical data and aberration diagrams, for each example, the various aberrations are corrected well, while maintaining good optical performance, the entire lens length is shortened, and miniaturization is achieved. A variable magnification optical system suitable for being mounted and thinned is realized.

  In addition, this invention is not limited to the said embodiment and each Example, A various deformation | transformation implementation is possible. For example, the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to the values shown in the above numerical examples, and may take other values.

1 is a lens cross-sectional view corresponding to Example 1, illustrating a first configuration example of a variable magnification optical system according to an embodiment of the present invention. FIG. 2 is a lens cross-sectional view corresponding to Example 2 and illustrating a second configuration example of a variable magnification optical system according to an embodiment of the present invention. FIG. FIG. 6 is a lens cross-sectional view illustrating a third configuration example of a variable magnification optical system according to an embodiment of the present invention and corresponding to Example 3; FIG. 9 is a lens cross-sectional view illustrating a fourth configuration example of a variable magnification optical system according to an embodiment of the present invention and corresponding to Example 4; 5 is a lens cross-sectional view corresponding to Example 5 and illustrating a fifth configuration example of a variable magnification optical system according to an embodiment of the present invention. FIG. 6 is a lens cross-sectional view illustrating a sixth configuration example of a variable magnification optical system according to an embodiment of the present invention and corresponding to Example 6. FIG. 7 is a lens cross-sectional view illustrating a seventh configuration example of a variable magnification optical system according to an embodiment of the present invention and corresponding to Example 7. FIG. It is sectional drawing which shows the example of the lens moving mechanism in the variable magnification optical system which concerns on one embodiment of this invention. 2A and 2B are diagrams illustrating lens data of a variable magnification optical system according to Example 1. FIG. 1A illustrates basic lens data, and FIG. 3B illustrates surface distance data of a portion that moves with zooming. FIG. 4 is a diagram illustrating data relating to an aspherical surface of the variable magnification optical system according to Example 1. FIG. 6 is a diagram illustrating lens data of a variable magnification optical system according to Example 2, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 6 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 2. FIG. 6 is a diagram illustrating lens data of a variable magnification optical system according to Example 3, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 6 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 3. FIG. 10 is a diagram illustrating lens data of a variable magnification optical system according to Example 4, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 10 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 4. FIG. 10 is a diagram illustrating lens data of a variable magnification optical system according to Example 5, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 10 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 5. FIG. 10 is a diagram illustrating lens data of a variable magnification optical system according to Example 6, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 10 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 6. FIG. 10 is a diagram illustrating lens data of a variable magnification optical system according to Example 7, wherein (A) illustrates basic lens data, and (B) illustrates data of a surface interval of a portion that moves with zooming. FIG. 10 is a diagram illustrating data relating to an aspherical surface of a variable magnification optical system according to Example 7. It is the figure which showed the value regarding a conditional expression collectively about each Example. FIG. 4 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 1. (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 4 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 1. (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 6 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 2, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 6 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 2, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 6 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 3, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 6 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 3. (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 6 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 4, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 4, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 5, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 5, where (A) is spherical aberration, (B) is astigmatism, (C) is distortion, and (D) is chromatic aberration of magnification. Show. FIG. 11 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 6, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 6, wherein (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion, and (D) shows chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the wide-angle end of the variable magnification optical system according to Example 7, wherein (A) is spherical aberration, (B) is astigmatism, (C) is distortion, and (D) is chromatic aberration of magnification. Show. FIG. 10 is an aberration diagram showing various aberrations at the telephoto end of the variable magnification optical system according to Example 7, wherein (A) is spherical aberration, (B) is astigmatism, (C) is distortion, and (D) is chromatic aberration of magnification. Show.

Explanation of symbols

  GC ... optical member, G1 ... first lens group, G2 ... second lens group, G3 ... third lens group, G4 ... fourth lens group, G5 ... fifth lens group, G1f ... front group in the first lens group G1r: rear group in the first lens group, G1p: reflecting member, LP: right-angle prism, St ... diaphragm, Ri ... curvature radius of the i-th lens surface from the object side, Di: i-th from the object side Surface distance from the (i + 1) th lens surface, Z1... Optical axis, 100.

Claims (7)

In order from the object side, a first lens unit having a fixed positive refractive power during zooming and focusing, a second lens unit having a negative refractive power moving during zooming, and zooming and focusing. A third lens group having a fixed positive refractive power, a fourth lens group having a positive refractive power that moves during zooming and has a focusing function, and a negative refractive power that moves during zooming It consists of a fifth lens group,
The first lens group includes, in order from the object side, a front group having negative refractive power, a reflecting member that bends the optical path, and a rear group having positive refractive power, and satisfies the following conditional expression: A variable magnification optical system characterized by being configured as follows.
−3.5 <f1f / f1r <−1.8 ( 1 )
However,
f1f: focal length of the front group in the first lens group f1r: focal length of the rear group in the first lens group. The zoom lens system according to claim 1 , further satisfying the following conditional expression:
0.5 <| f2 / fw | <0.8 (2)
However,
fw: focal length of the entire system at the wide angle end f2: the focal length of the second lens group. Furthermore, the following conditional expression is satisfied
The variable magnification optical system according to claim 1 or 2, wherein
0.4 <fw / f1 <0.8 (3)
However,
fw: focal length of the entire system at the wide-angle end
f1: Focal length of the first lens group At the time of zooming, the second lens group and the fifth lens group move in different movement directions on the optical axis and move linearly together, and the fourth lens group moves nonlinearly. The zoom lens system according to any one of claims 1 to 3 , wherein the zoom lens system moves so as to perform. The first to the variable-power optical system according to any one of claims 1 to 4, characterized in that it comprises at least one plastic lens in the fifth lens each lens group of the group. The first lens group has at least one positive lens in the rear group,
The second lens group has at least one negative lens,
A plastic lens is used for at least one of the positive lenses in the rear group in the first lens group, and a plastic lens is used for at least one of the negative lenses in the second lens group. variable-power optical system according to any one of claims 1 to 5, characterized. A variable magnification optical system according to any one of claims 1 to 6 ,
An imaging device comprising: an imaging element that outputs an imaging signal corresponding to an optical image formed by the zoom optical system.

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