Lens device and imaging device

Abstract

To provide a lens device capable of positioning a lens with high accuracy while reducing lens surface distortion with a simple configuration.SOLUTION: A lens device comprises a lens, a holding lens barrel that holds the lens, a biasing barrel that holds the lens between the holding lens barrel and the biasing barrel, and an elastic member that biases the biasing barrel toward the holding lens barrel. The holding lens barrel includes an optical axis direction receiving portion for positioning the lens in an optical axis direction and an orthogonal direction receiving portion for positioning the lens in an orthogonal direction to an optical axis. The elastic member biases the biasing barrel to cause the lens to be pressed against the optical axis direction receiving portion and the orthogonal direction receiving portion and cause the lens to be held with respect to the holding lens barrel in the optical axis direction and the orthogonal direction, and the lens device comprises a movement amount limiting portion that limits a relative movement amount between the biasing barrel and the holding lens barrel in the optical axis direction and the orthogonal direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to lens an apparatus and an imaging device.

Background Art

[0002] In a lens barrel such as an interchangeable lens, there is a case where a thermal caulking or an adhesive is used to fix a lens to the lens barrel. In this case, due to the stress generated to fix the lens to the lens barrel, a change (lens surface distortion) may occur in the surface accuracy of the lens surface, and the optical performance of the lens may deteriorate.

[0003] Patent Document 1 discloses a technique for biasing and fixing a lens to a lens holder by pressing the lens toward a holding recess of the lens holder with a pressing member that snap-fits to the lens holder. The pressing portion, which is the portion of the pressing member that presses the lens, has an elastic material such as a foamed material or rubber arranged in a ring shape, and the lens is pressed against the lens holder via the elastic material. Thereby, a technique for fixing the lens to the lens holder while suppressing lens surface distortion is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to suppress distortion of the lens surface caused by the stress for fixing the lens when fixing the lens to the lens barrel, it is necessary to fix the lens with a weak force. Specifically, when the lens mass is about 10 g, if the lens is pressed and fixed with a force of about 500 mN, the stress acting on the lens with respect to the rigidity of the lens is small, and the distortion of the lens surface can be suppressed to a small extent.

[0006] However, when fixing the lens via an elastic member placed in a narrow slit between it and the pressing member, the spring constant of the elastic member becomes very large, and the pressing force also becomes large. Furthermore, it is not easy to fix each lens with the same force without variation.

[0007] Patent Document 1 does not disclose any method for fixing the lens in a direction perpendicular to the optical axis. Even when the lens is pressed into the lens barrel for fixation, the resulting stress can worsen the distortion of the lens surface. Furthermore, if there is play between the lens barrel that holds the lens and the optical axis of the lens, the lens may move, worsening the accuracy of the lens position and potentially degrading the optical performance of the lens.

[0008] Therefore, the present invention aims to provide a lens device that can position lenses with high precision while minimizing lens surface distortion, using a simple configuration. [Means for solving the problem]

[0009] To achieve the above objective, one aspect of the present invention is lens The device is lens And, as stated above lens Hold hold mirror A cylinder and the retainer mirror Between the cylinder and the above lens A biasing cylinder that holds the biasing cylinder, and the holding mirror It has an elastic member that biases toward the cylinder, and the holding mirror The cylinder is the aforementioned lens An optical axis receiving portion for positioning in the optical axis direction, and lens It has an orthogonal receiving portion for positioning in a direction perpendicular to the optical axis, and the biasing cylinder is biased by the elastic member, lens The optical axis receiving portion and the orthogonal direction receiving portion are pressed against the holding portion. mirror Positioned and held in the optical axis direction and the orthogonal direction with respect to the cylinder, lens With the position and holding state, the biasing cylinder and the holding in the optical axis direction and the orthogonal direction mirrorIt is characterized by having a movement amount limiting part that limits the relative movement amount of the cylinder.

Advantages of the Invention

[0010] In the present invention, a lens device capable of positioning a lens with high precision while reducing lens surface distortion with a simple configuration is provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic diagram showing the configuration of an imaging device including the lens barrel of the present invention. [Figure 2] It is a diagram showing the configuration of the lens barrel of the present invention. [Figure 3] It is a diagram showing the configuration of the lens barrel of the present invention. [Figure 4] It is a cross-sectional view taken along A-A of FIG. 2. [Figure 5] It is a cross-sectional view taken along B-B of FIG. 3.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

Examples

[0013] Referring to FIG. 1, the system configuration of the imaging device 1 including the lens device 100 and the camera device 200 of the present invention will be described.

[0014] The lens device 100 includes, in order from the object side (the left side in FIG. 1) to the image side (the right side in FIG. 1), a first lens group 101, a second lens group 102, a third lens group 103, an aperture unit 104, a fourth lens group 105, and a fifth lens group 106. The second lens group 102 is supported by a lens barrel having a mechanism that can move with a component perpendicular to the optical axis, and constitutes an image blur correction unit that is driven in a plane perpendicular to the optical axis for image blur correction. The fourth lens group 105 is supported by a lens barrel that can move in the optical axis direction, and is a focus lens group that performs focus adjustment by moving in the optical axis direction. The first lens group 101, the third lens group 103, and the fifth lens group 106 are held by a lens barrel that does not move in the optical axis direction.

[0015] Each of the first lens group 101, the second lens group 102, the third lens group 103, the fourth lens group 105, and the fifth lens group 106 is composed of one or more lenses. In optical operations such as zooming, focus adjustment, and image blur correction, the positional relationship of the lenses within each lens group does not change.

[0016] The lens device 100 also includes a gyro sensor 111 as detection means for detecting the vibration of the lens device 100, and a lens control unit 110 that performs drive control of the movable lens groups and the aperture stop.

[0017] The lens control unit 110 controls an aperture drive unit 113 and a focus lens drive unit 114 to drive the aperture unit 104 and the fourth lens group 105, and changes the aperture diameter and performs focus adjustment.

[0018] Based on the detection value of the gyro sensor 111, the lens control unit 110 calculates an image blur correction amount, controls an image blur correction drive unit 112, and performs image blur correction. The image blur correction is performed by driving the second lens group 102 in the y direction (yaw direction) and the p direction (pitch direction) that are perpendicular to each other in a plane perpendicular to the optical axis direction (the x direction in the figure).

[0019] Furthermore, the lens control unit 110 also has the function of determining the holding state (change in posture) of the lens device 100 or the camera device 200 based on the detected value of the gyro sensor 111.

[0020] The lens device 100 is detachably connected to the camera device 200 via a mount 120. The camera device 200 has an image sensor 201 and captures an image of the subject formed by the optical system in the lens device 100.

[0021] The camera device 200 is equipped with a camera control unit 202, a release button 203 as an operating element, a main power control unit 204, a recording unit 205, and the like. The release button 203 has a two-stage configuration, allowing for a first release operation with a shallow press depth and a second release operation with a deeper press depth. When the first release operation is performed, the camera control unit 202, in cooperation with the lens control unit 110 as needed, prepares for shooting, such as returning from shooting standby, starting image blur correction, starting autofocus, and starting metering. When the second release operation is performed, the camera control unit 202 takes a picture and records the image to the recording unit 205.

[0022] Furthermore, power is exchanged between the camera device 200 and the lens device 100 via a contact block (not shown) provided on the mount 120, and shooting information is communicated between the camera control unit 202 and the lens control unit 110.

[0023] A lens barrel according to Embodiment 1 of the present invention will be described with reference to Figures 2 to 5.

[0024] Figures 2 to 5 show a five-group lens barrel 300 holding a fifth lens group 106, which is an example of an embodiment 1 of the present invention.

[0025] Figure 2 is a view of the 5-group lens barrel 300 from the object side along the optical axis. Figure 3 is a side view of the 5-group lens barrel 300, viewed from the bottom of the paper in Figure 2. Figure 4 is a cross-sectional view AA of Figure 2. Figure 5 is a cross-sectional view BB of Figure 3.

[0026] The 5-group lens barrel 300 is a lens barrel that holds the lens 301 constituting the 5th lens group 106, and includes a biasing barrel 302, a holding barrel 303, and an elastic member 304. In this embodiment, the elastic member 304 is composed of two tension coil springs, but the present invention is not limited thereto, and may be composed of a compression coil spring, a leaf spring, rubber, etc. The elastic member 304 has a first hook portion provided at one end that engages with the elastic member fixing portion 302e of the biasing barrel 302, and a second hook portion provided at the other end that engages with the elastic member fixing portion 303e of the holding barrel 303. The two elastic members 304 are positioned substantially opposite each other across the optical axis O.

[0027] The two tension coil springs of the elastic member 304 are positioned at an angle of approximately 45 degrees with respect to a plane perpendicular to the optical axis O. This arrangement causes the resultant force of the tensile forces from the two tension coil springs to act in a direction inclined approximately 45 degrees with respect to the plane perpendicular to the optical axis O. Here, approximately 45 degrees with respect to the plane perpendicular to the optical axis means an angle of 30 degrees or more and 60 degrees or less, preferably 40 degrees or more and 50 degrees or less, and more preferably 42 degrees or more and 48 degrees or less with respect to the plane perpendicular to the optical axis.

[0028] Furthermore, the two tension coil springs of the elastic member 304 are arranged so that their extension directions are substantially parallel to each other. Arranging the two tension coil springs of the elastic member 304 substantially parallel to each other is preferable because the resultant elastic force of each spring efficiently acts as a biasing force on the lens 301. Here, the arrangement where the extension directions of the two tension coil springs are substantially parallel to each other means that the angle between the extension direction of one spring and the extension direction of the other spring is 10 degrees or less, preferably 5 degrees or less, and more preferably 3 degrees or less.

[0029] As shown in Figure 3, the biasing tube 302 is biased by the elastic member 304 toward the retaining lens barrel 303 in a direction diagonally downward to the left of the paper (in a direction tilted approximately 45 degrees with respect to the plane perpendicular to the optical axis). The lens 301 is positioned sandwiched between the retaining lens barrel 303 and the biasing tube 302 in the plane perpendicular to the optical axis and in the plane perpendicular to the optical axis.

[0030] The lens holder 303 has optical axis receiving portions 303c at three locations at approximately equal intervals of approximately 120 degrees in the circumferential direction around the optical axis, which receive the lens 301 in the optical axis direction. The biasing tube 302 has optical axis biasing portions 302c at three locations at approximately equal intervals of approximately 120 degrees in the circumferential direction around the optical axis. The lens 301 is pressed against the optical axis receiving portions 303c by the optical axis biasing portions 302c of the biasing tube 302, which are subjected to elastic force from the elastic member 304, and is positioned in the optical axis direction. The optical axis receiving portions 303c may be configured at three or more locations, or they may be configured around the entire circumference.

[0031] The optical axis biasing portion 302c may be configured at three or more locations, or it may be configured around the entire circumference.

[0032] As mentioned above, the resultant force of the biasing force acting on the biasing cylinder 302 by the two tension coil springs, which are elastic members 304, acts near the optical axis. Therefore, the biasing cylinder 302 can bias the lens 301 near its center of gravity in the direction of the optical axis relative to the holding lens barrel 303. As a result, the lens 301 can be biased and positioned in a balanced and even manner. This prevents the axis of the lens 301 from tilting relative to the optical axis of the optical system of the lens device 100, which would otherwise degrade the overall optical performance of the lens device, due to the resultant force of the biasing force acting at a position away from the center of gravity of the lens 301.

[0033] The lens holder 303 has two optical axis orthogonal bearing portions 303d for positioning the lens 301 in a plane perpendicular to the optical axis. The biasing cylinder 302 is biased to the left side of the paper in Figure 3 by a biasing force having a component in a plane perpendicular to the optical axis, provided by two tension coil springs. The two optical axis orthogonal bearing portions 303d located on the lens holder 303 are positioned on the opposite side of the biasing cylinder 302 from the side where the two elastic member fixing portions 302e are located, with respect to a first plane parallel to the optical axis passing through the two elastic member fixing portions 303e. Furthermore, the two optical axis orthogonal bearing portions 303d are positioned symmetrically with respect to a second plane perpendicular to the first plane and containing the optical axis, and are positioned approximately 120° apart from each other with respect to the optical axis.

[0034] Furthermore, in this embodiment, the optical axis orthogonal direction receiving portion 303d is configured to have a circular arc shape with radius L1 centered at the position of the optical axis in a plane perpendicular to the optical axis. However, the optical axis orthogonal direction receiving portion 303d is not limited to being formed as a circular arc shape in a plane perpendicular to the optical axis, and may, for example, be configured as a D-cut. In that case, the optical axis orthogonal direction receiving portion 303d is configured such that the distance between the D-cut plane and the optical axis is L1.

[0035] The retaining lens barrel 303 is provided with a guide portion 303f on the side opposite to the optical axis perpendicular receiving portion 303d with respect to the first plane. The guide portion 303f is provided to temporarily assemble and roughly position the lens 301 and the retaining lens barrel 303 before the biasing barrel 302 is assembled to the retaining lens barrel 303. The guide portion 303f is formed in the shape of an arc with a radius L2 centered on the optical axis position. The portion of the retaining lens barrel 303 corresponding to the position of the optical axis perpendicular biasing portion 302d of the biasing barrel 302, which will be described later, is notched so that the optical axis perpendicular biasing portion 302d can contact the outer diameter portion of the lens 301 and bias it.

[0036] The biasing cylinder 302 has an optical axis orthogonal biasing portion 302d on the opposite side of the optical axis orthogonal receiving portion 303d with respect to the first plane, which biases the lens 301 toward the optical axis orthogonal receiving portion 303d (to the left in Figure 5) by the biasing force of the elastic member 304. As a result, the lens 301 is positioned in a plane perpendicular to the optical axis with respect to the holding barrel 303.

[0037] Here, the radius L1 of the optical axis centered on the optical axis of the optical axis receiving portion 303d, the radius L2 of the optical axis centered on the optical axis of the guide portion 303f, and the radius R of the outer diameter of the lens 301 are: L1=R ··· (1) R <L2 ··· (2) The following relationship is satisfied. That is, when the lens 301 is in contact with the optical axis direction receiving portion 303c and the optical axis perpendicular direction receiving portion 303d, the guide portion 303f is configured such that there is play between the holding lens barrel 303 and the lens 301 in at least one direction in a plane perpendicular to the optical axis.

[0038] First, by configuring the lens holder 303 to satisfy equation (1), the lens 301 is positioned with play against the optical axis perpendicular receiving portion 303d of the lens holder 303, so that the lens 301 can be fixed to the lens holder 303 without eccentricity. This prevents a decrease in the overall optical performance of the lens device 100. Also, the difference between radii L2 and L1 (L2-L1) (>0) is set to be as small as possible within the range in which the lens 301 can be temporarily assembled to the lens holder 303, taking into account manufacturing tolerances, etc. Regarding this difference (L2-L1), when the lens 301 is temporarily assembled to the lens holder 303, it is sufficient that the lens 301 and the lens holder 303 are held in a plane perpendicular to the optical axis with some play, rather than being press-fitted. For example, L2 should be set to be, for example, 0.01 mm larger than L1. In the illustrated embodiment, the guide portion 303f is shown to be formed in the shape of an arc with radius L2 centered on the optical axis position, but the present invention is not limited to this shape. The guide portion 303f is provided on the opposite side of the receiving portion 303d perpendicular to the optical axis with respect to the first plane, with the closest position being at a distance R from the optical axis position.

[0039] As a result, the lens 301 is not pressed into the retaining barrel 303 during the temporary holding stage, and no stress is applied to the lens 301, thus preventing the deterioration of lens surface distortion.

[0040] Furthermore, when the lens 301 is temporarily held in the retaining barrel 303, the lens 301 is held in a position close to the completed assembly of the biasing barrel 302, making subsequent assembly and fixing easier. Also, when the assembly is completed, if an impact force having a component perpendicular to the optical axis and in the opposite direction to the biasing force of the elastic member 304 is applied to the lens device 100, the biasing barrel 302 and the lens 301 will be displaced relative to the retaining barrel 303. However, since the lens 301 is in contact with the guide portion 303f of the retaining barrel 303, the lens 301 will not be displaced by a magnitude greater than the difference between L2 and L1.

[0041] Thus, the elastic member 304 that biases the lens 301 to the holding barrel 303 via the biasing cylinder 302 biases the lens 301 at an angle with respect to the optical axis, and thus the biasing cylinder 302 alone can position the lens 301 in both the direction of the optical axis and in a plane perpendicular to the optical axis.

[0042] For positioning the lens 301 in the optical axis direction, the biasing tube 302 causes the lens 301 to be positioned by playfully pushing it towards the optical axis receiving portion 303c of the retaining lens barrel 303. By precisely creating the surface of the optical axis receiving portion 303c, the position of the lens 301 in the optical axis direction can be precisely positioned, preventing the lens from becoming distorted. The biasing force in the optical axis direction by the elastic member 304 is set to a force of about 2 to 10 times the lens mass. Specifically, if the lens mass is 10g, the biasing force in the optical axis direction by the elastic member 304 is set to about 200mN to 1000mN. This is smaller than, for example, the stress applied when fixing the lens to the lens barrel by heat crimping, and it is possible to suppress the distortion generated on the lens surface and prevent deterioration of optical performance.

[0043] The positioning of the lens 301 in a direction perpendicular to the optical axis is achieved by the biasing cylinder 302, which causes the lens 301 to playfully move towards the optical axis perpendicular receiving portion 303d of the retaining lens barrel 303. Since the distance L1 from the optical axis (radius of the arc) of the optical axis perpendicular receiving portion 303d and the radius R of the lens 301 are set to L1 = R, the lens 301 has a reference surface that allows it to be positioned with good eccentricity accuracy relative to the retaining lens barrel 303. The biasing force applied by the elastic member 304 to the lens 301 in a direction perpendicular to the optical axis is set to a force of about 2 to 10 times the lens mass. Specifically, if the lens mass is 10g, the biasing force in the optical axis direction by the elastic member 304 is set to about 200mN to 1000mN. This is, for example, very small compared to the stress applied to the lens 301 when it is press-fitted radially into the retaining lens barrel 303 and fixed. Therefore, when fixing the lens to the lens barrel according to the present invention, the distortion generated on the lens surface can be kept to a minimum, and the deterioration of optical performance can be suppressed.

[0044] In this embodiment, a tension coil spring is used as the elastic member 304. If a wave washer is used as the elastic member 304, it is difficult to secure a sufficiently long space for placement in the biasing direction, making it difficult to reduce the spring constant. As a result, even a slight change in the position in the biasing direction (compression length of the wave washer) can cause a large change in the biasing force, making it difficult to apply the desired biasing force. As mentioned above, if the desired biasing force is a relatively small biasing force of about 200mN to 1000mN, it becomes even more difficult to apply the desired biasing force. In the case of resin springs or rubber, the spring constant becomes large, making it difficult to apply the desired biasing force, and there is also a concern that the biasing force will change over time if creep occurs.

[0045] When tension is used, if the spring length can be secured, the spring constant can be set small, and it is easy to achieve a weak biasing force as per the design value. Furthermore, the risk of the biasing force changing over time can be kept low. Therefore, in this embodiment, both the application of the desired biasing force and space-saving arrangement are achieved. As for the elastic member 304, not only tension coil springs but also leaf springs and the like can be used as long as the above requirements are met.

[0046] In order to stably and accurately bias and fix the lens 301, the resultant force of the biasing forces acting on the two elastic member fixing parts 302e where the elastic member 304 engages must act near the center of gravity P of the lens 301. The region V shown in Figure 4 represents the area within half the distance from the center of gravity P of the lens 301 to the outer shape of the lens 301. That is, region V is the area enclosed by the midpoint of the line segment from the center of gravity P of the lens 301 to the outer shape of the lens 301. If the resultant force of the biasing forces by the elastic member 304 is configured to act within region V, the lens 301 can be stably and accurately biased and fixed to the lens barrel 303.

[0047] Conversely, if the resultant force of the biasing forces acts at a position outside region V, the resultant force of the biasing forces and the reaction force of the optical axis axial support portion 303c to the biasing forces become unbalanced, and the lens may not be held down sufficiently at the phase where the biasing force is weak, potentially causing the lens to tilt. Also, if the resultant force of the biasing forces acts at a position far outside region V, the relationship with the reaction force from the optical axis axial support portion 303c to the biasing forces may cause the lens to tilt due to the moment, especially when an impact force is applied from the outside.

[0048] In this case, in order to apply a biasing force within the region V of the lens 301, two elastic member fixing parts 302e, which engage with tension coil springs (elastic members 304), are positioned approximately opposite each other, with the vicinity of the center of gravity P of the lens 301 in between. Furthermore, as shown in Figure 3, the two tension coil springs are positioned approximately parallel to each other and at an angle of approximately 45 degrees with respect to a plane perpendicular to the optical axis. This arrangement makes it possible to apply the resultant force of the biasing forces within region V with a small number of springs and a small space. The elastic member 304 is not limited to being composed of two tension coil springs; three or more elastic members may be used as long as it is possible to bias the lens 301 so that the resultant force of the biasing forces acts within region V.

[0049] Next, we will describe the assembly of this unit. First, the lens 301 is placed in the retaining barrel 303, aligned with the optical axis perpendicular receiving portion 303d and the guide portion 303f. Since the lens 301 is not press-fitted in the radial direction, no special tools are required, and the lens 301 can be easily placed in the optical axis direction receiving portion 303c of the retaining barrel 303 without applying stress to press-fit the lens 301.

[0050] Next, the biasing tube 302 is assembled into the lens barrel 303. The biasing tube 302 has three bayonet claws 302g that engage with the lens barrel 303, spaced 120 degrees apart. The lens barrel 303 has three bayonet grooves 303g that correspond to the bayonet claws 302g, spaced 120 degrees apart. The lens barrel 303 has an assembly groove for the bayonet claws 302g to pass through when assembling the biasing tube 302, located approximately 15 degrees around the optical axis from the position where the bayonet grooves 303g are located. When assembling the biasing tube 302 into the lens barrel 303, in this phase state, the biasing tube 302 is inserted into the lens barrel 303 to a predetermined optical axis position, and then rotated 15 degrees to assemble it into the completed position shown in Figure 2. This is similar to the configuration and assembly of a typical bayonet system.

[0051] In this state, the tension coil springs are fixed by hooking the hook portions of the two tension coil springs, which are elastic members 304, onto the elastic member fixing portions 302e and 303e. As a result, the rotational phase position of the biasing tube 302 with respect to the relative optical axis of the holding tube 303 is also determined.

[0052] As described above, the lens 301 can be easily and precisely fixed to the lens barrel 303 without using any special tools, such as those used for heat crimping of lenses, during assembly.

[0053] Next, I will explain the behavior of the lens device when it is subjected to impact. As shown in Figure 4, when the lens 301 is assembled to the lens barrel 303 by the biasing cylinder 302 and the elastic member 304, the optical axis perpendicular stopper portion 302b and the optical axis perpendicular stopper portion 303b are configured to have a gap d2 in a direction perpendicular to the optical axis. It is desirable to make the gap d2 as small as possible, within a range that cannot be zero even considering manufacturing variations of the parts.

[0054] Between the bayonet groove 303g provided in the retaining barrel 303 and the bayonet claw 302g provided in the biasing barrel 302, the optical axis direction stopper portion 303a and the optical axis direction stopper portion 302a are configured to have a gap d1 in the optical axis direction. The gap d1 is not zero even when considering manufacturing variations of the parts, but it is desirable to make it as small as possible.

[0055] With the bayonet mechanism described above, when the lens 301 is held in place, there is relative positional play between the biasing barrel 302 and the holding barrel 303 in the direction perpendicular to the optical axis, and a movement limiting unit is configured to limit the relative amount of movement.

[0056] If the lens device 100 is subjected to an impact such as a fall, and a force greater than the biasing force applied in the opposite direction to the biasing force by the elastic member 304 of the biasing cylinder 302 is applied, the biasing cylinder 302 will move in the opposite direction to the biasing force. As a result, the lens 301 will move in the same way. However, in the direction perpendicular to the optical axis, the optical axis perpendicular direction stopper portion 302b and the optical axis perpendicular direction stopper portion 303b act as stoppers that define the limit of movement, and the relative displacement of the biasing cylinder 302 and the lens 301 will not exceed d2. When the impact force is removed, the biasing force of the elastic member 304 will return the device to its original positioning position.

[0057] In the optical axis direction, the optical axis direction stopper portion 303a of the holding barrel 303 and the optical axis direction stopper portion 302a of the biasing barrel 302 act as stoppers that define the limit of movement, so that the relative displacement of the biasing barrel 302 and the lens 301 does not exceed d1. When the impact force is removed, the biasing force of the elastic member 304 returns them to their original positioning position.

[0058] In this case, if the gap d2 perpendicular to the optical axis and the gap d1 in the direction of the optical axis are large, the relative amount of movement between the biasing barrel 302 and the lens 301 will also be large. However, in this embodiment, since the gaps d2 and d1 are set to be small, the amount of movement is small. This reduces the risk of the lens tilting and twisting when the amount of movement is large, and the risk of it stopping before reaching the position due to friction when the amount of movement is small or when it is press-fitted and fixed. In other words, even if the lens device 100 is subjected to an impact, the relative positional relationship between the lens 301 and the retaining barrel 303 remains unchanged and it is easy to return to the original relative positional relationship. In short, it is possible to realize a lens in which the optical performance does not change much even when an impact is applied.

[0059] As described above, by applying the configuration of this embodiment, lens surface distortion can be reduced and the lens can be positioned with high precision, thereby realizing a lens device that prevents deterioration of optical performance due to the assembly of the lens into the lens device. In particular, in order to reduce the overall length and weight of the lens, it is desirable to make the thickness of the lens at the center and at the periphery as thin as possible. However, when the thickness of the lens is reduced, the rigidity of the lens decreases, making it more susceptible to distortion of the lens surface. Even in such cases, the present invention can be used to suppress distortion of the lens surface and realize a high-performance lens.

[0060] Furthermore, even if distortion occurs on the lens surface, if similar distortion occurs on the object side and the image side (back surface) of the lens, the adverse effect on optical performance may be canceled out. On the other hand, when using mirror lenses (reflective optical elements) used in telescopes, etc., there is no such cancellation relationship as described above, so the surface distortion of the mirror lens directly leads to a deterioration of optical performance. In this invention, since the lens surface distortion itself can be kept small without relying on a cancellation relationship, it is also effective for the holding configuration of mirror lenses.

[0061] In this embodiment, an example of application to the fifth lens group was illustrated, but the present invention is not limited thereto and can be applied to positioning and fixing lenses to the lens barrel in other lens groups. Furthermore, in the above embodiment, an example of application to a lens group that does not move for focusing or zooming was illustrated, but the present invention is not limited thereto and can be similarly applied to a lens group that moves. When applying to a moving lens group, it is advisable to determine the magnitude of the elastic force that biases the lens by considering the acceleration and direction during movement.

[0062] This embodiment includes the following configuration. (Composition 1) Lens and, A retaining barrel for holding the aforementioned lens, A biasing cylinder that holds the lens between itself and the aforementioned retaining lens barrel, The biasing cylinder has an elastic member that biases it toward the holding lens barrel, The lens barrel has an optical axis receiving portion for positioning the lens in the optical axis direction and an orthogonal receiving portion for positioning the lens in a direction perpendicular to the optical axis. By biasing the biasing cylinder with the elastic member, the lens is pressed against the optical axis receiving portion and the orthogonal direction receiving portion, and is positioned and held in the optical axis direction and the orthogonal direction relative to the holding lens barrel. A lens device characterized by having a movement limiting unit that limits the relative amount of movement between the biasing cylinder and the holding lens barrel in the optical axis direction and the orthogonal direction when the lens is positioned and held. (Configuration 2) The lens device according to configuration 1, characterized in that, when the lens is in contact with the optical axis axial receiving portion and the orthogonal receiving portion, the holding lens barrel has a guide portion configured such that the lens has play in a plane perpendicular to the optical axis. (Composition 3) The orthogonal receiving portion has an arc shape with the radius of the lens as its radius, The guide portion has an arc shape centered on the position of the optical axis of the lens when the lens is in contact with the optical axis receiving portion and the orthogonal direction receiving portion. The lens device according to configuration 2, characterized in that the radius of the arc shape of the guide portion is larger than the radius of the lens. (Composition 4) The lens device according to any one of configurations 1 to 3, characterized in that the movement limiting unit is a bayonet mechanism configured between the holding lens barrel and the biasing barrel. (Composition 5) The lens device according to any one of configurations 1 to 4, characterized in that the elastic member is composed of at least two coil springs. (Composition 6) The lens device according to configuration 5, characterized in that the resultant force of the biasing forces acting on the lens by the at least two coil springs acts in a region within half the distance from the center of gravity of the lens to its outer shape. (Composition 7) The elastic member consists of two coil springs. The two coil springs are positioned opposite each other, with the center of gravity of the lens in between. One end of each of the two coil springs engages with the retaining lens barrel, and the other end of each of the two coil springs engages with the biasing barrel, and they are positioned obliquely to a plane perpendicular to the optical axis. A lens device as described in any of configurations 1 to 6. (Composition 8) The lens device according to configuration 7, characterized in that each of the two coil springs is arranged to have an angle of 30 degrees or more and 60 degrees or less with respect to a plane perpendicular to the optical axis. (Composition 9) The lens device according to configuration 7, characterized in that each of the two coil springs is arranged to have an angle of 40 degrees or more and 50 degrees or less with respect to a plane perpendicular to the optical axis. (Composition 10) The lens device according to configuration 7, characterized in that the two coil springs are arranged parallel to each other. (Composition 11) An imaging device characterized by having a lens device described in any of configurations 1 to 10, and an image sensor for capturing an image formed by the lens device. [Explanation of symbols]

[0063] 100 Lens device 106 Fifth lens group 301 Lens 302 Force tube 303 Retaining lens barrel 304 Elastic member 303c Optical axis receiving part 303d Optical axis perpendicular direction receiving part

Claims

1. A lens and, A retaining barrel for holding the aforementioned lens, A biasing cylinder that holds the lens between itself and the aforementioned retaining lens barrel, The biasing cylinder has an elastic member that biases it toward the holding lens barrel, The lens barrel has an optical axis receiving portion for positioning the lens in the optical axis direction and an orthogonal receiving portion for positioning the lens in a direction perpendicular to the optical axis. By biasing the biasing cylinder with the elastic member, the lens is pressed against the optical axis receiving portion and the orthogonal direction receiving portion, and is positioned and held in the optical axis direction and the orthogonal direction relative to the holding lens barrel. A lens device characterized by having a movement limiting unit that limits the relative amount of movement between the biasing cylinder and the holding lens barrel in the optical axis direction and the orthogonal direction when the lens is positioned and held.

2. The lens device according to claim 1, characterized in that, when the lens is in contact with the optical axis axial receiving portion and the orthogonal receiving portion, the holding lens barrel has a guide portion configured such that the lens has play in a plane perpendicular to the optical axis.

3. The orthogonal receiving portion has an arc shape with the radius of the lens as its radius, The guide portion has an arc shape centered on the position of the optical axis of the lens when the lens is in contact with the optical axis receiving portion and the orthogonal direction receiving portion. The lens device according to claim 2, characterized in that the radius of the arc shape of the guide portion is larger than the radius of the lens.

4. The lens device according to claim 1, characterized in that the movement limiting part is a bayonet mechanism configured between the holding lens barrel and the biasing barrel.

5. The lens device according to claim 1, characterized in that the elastic member is composed of at least two coil springs.

6. The lens device according to claim 5, characterized in that the resultant force of the biasing forces acting on the lens by the at least two coil springs acts in a region within half the distance from the center of gravity of the lens to its outer shape.

7. The elastic member is two coil springs, The two coil springs are positioned opposite each other, with the center of gravity of the lens in between. One end of each of the two coil springs engages with the retaining lens barrel, and the other end of each of the two coil springs engages with the biasing barrel, and they are positioned obliquely to a plane perpendicular to the optical axis. The lens device according to claim 1.

8. The lens device according to claim 7, characterized in that each of the two coil springs is arranged to have an angle of 30 degrees or more and 60 degrees or less with respect to a plane perpendicular to the optical axis.

9. The lens device according to claim 7, characterized in that each of the two coil springs is arranged to have an angle of 40 degrees or more and 50 degrees or less with respect to a plane perpendicular to the optical axis.

10. The lens device according to claim 7, characterized in that the two coil springs are arranged parallel to each other.

11. An imaging device characterized by having a lens device according to any one of claims 1 to 10, and an image sensor for capturing an image formed by the lens device.

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