JPH0943471A - Lens moving mechanism - Google Patents

Abstract

(57) Abstract: To reduce play caused by a gap in a direction perpendicular to an optical axis of a moving mechanism in a lens moving mechanism that performs focus adjustment and focus detection by moving in the optical axis direction. A holding member for holding a lens is held by an elastic member on a disk with respect to an outer cylinder, and the holding member is pressed in the optical axis direction by a pressing member.
In particular, the elastic member is composed of a metallic thin film plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens moving mechanism for moving an optical lens group in an optical axis direction in a photographing lens device.

[0002]

2. Description of the Related Art Conventionally, in photographing lens devices,
A mechanism as shown in FIG. 12 is used as a mechanism for moving the lens group in the optical axis direction such as optical tracking adjustment. In the figure, 71 is a moving lens group, 72 is a lens holding member for holding 71, 73 is a fixed portion (fixed lens barrel) of the lens barrel main body corresponding to the outer cylinder, and the lens holding member 72 is the fixed portion 73. It is possible to move straight in the direction of the optical axis by fitting it into the hole provided in. Reference numeral 74 is a ring member having a cam groove, which is fitted to the outer periphery of the fixed portion 73 and is rotatable about the optical axis. Reference numeral 75 denotes a pin member, which is attached to the lens holding member 72 and has a straight groove provided in the fixing portion 73.
It is fitted in the cam groove of the ring member 74.

In the above-described structure, when the ring member 74 is rotated manually or electrically using a motor or the like as shown in FIG. 12, the pin member 75 causes the ring member 7 to rotate.
4 along with the cam groove of 4 and the straight groove of the fixed portion 73,
The lens holding member 72 to which the pin member 75 is attached moves straight in the optical axis direction. The moving lens group 71 is
The lens is moved straight in the optical axis direction to achieve the intended optical lens adjustment.

[0004]

However, in the above-mentioned conventional example, since the lens holding member 72 is frictionally slid at the fitting portion with the hole of the fixing portion 73 and moves linearly, the lens holding member 72 is applied with a small force. In order to move smoothly, it is necessary that there is an appropriate gap between the fitting portion between the lens holding member 72 and the fixed portion 73. Therefore, as shown in FIG. 13A, the lens holding member 72 may be eccentric, or as shown in FIG. 13B, the lens holding member 72 may be tilted due to backlash to deteriorate the optical performance.

[0005]

SUMMARY OF THE INVENTION The present invention is to prevent the occurrence of tilting and decentering of a moving lens caused by a conventional movement in the optical axis direction. The cylinder is held by a disk-shaped elastic member, and the holding member is pressed in the optical axis direction by a pressing member. Particularly, by configuring the elastic member with a metallic thin film plate, Even if the lens moves in the optical axis direction, decentering in the direction perpendicular to the optical axis is suppressed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention. In the figure, 1 is a moving lens group, 2 is a lens holding member for holding the moving lens, and 3 is a fixed portion (fixed lens barrel) of the lens barrel main body. Reference numeral 4 denotes a metallic thin elastic disk having copper as a main component, which holds the lens holding member 2 so as to cover the entire periphery thereof, and the outer diameter portion is fixed to the fixing portion 3. Further, the lens holding member 2 and the elastic disc 4 do not rotate with respect to the fixed portion 3. Reference numeral 5 denotes a cam member having a surface cam 5a on its end surface, which is rotatable with respect to the fixed portion 3. Reference numeral 6 denotes an operation ring member, which is connected to the cam member 5 via the pin member 7 and is rotatable with respect to the fixed portion 3. Reference numeral 8 denotes a cam follower member provided on the holding member, two or more of which are the lens holding member 2.
Are attached at positions symmetrical with respect to the optical axis center, and abut on two surface cams of the cam member 5, respectively. Here, the same number of surface cams as the cam follower members 8 are machined on the cam members. Further, the elastic disc 4 is almost flat in the unloaded state, but is always deformed when incorporated in the mechanism of this embodiment, and its elastic force is constantly pressed between the cam follower 8 and the surface cam of the cam member 5. It is attached with force.

In such a structure, when the operation ring 6 is rotated manually or electrically by a motor or the like, the cam member 5 connected by the pin member 7 also rotates. When 5 rotates, the cam follower 8 is pushed out by the surface cam 5 as shown in FIG. 1 (B), the lens holder 2 moves in the optical axis direction, and the lens group 1 also moves. The elastic disk is
As described above, since it is made of a metal thin film, even if it is deformed in the optical axis direction, it is hardly decentered with respect to the direction perpendicular to the optical axis.

On the other hand, when the operation ring 6 is rotated in the opposite direction from the above state, the cam member 5 is also rotated in the reverse direction, and the cam follower 8 is rotated.
The amount of displacement of the surface cam at the position where is abutted is reduced. This time,
Since the lens barrel 2 is pushed toward the cam member by the elastic force of the elastic disc 4, the cam follower 8 moves according to the surface cam, and the lens holding member 2 also moves in the opposite direction.

In this way, by rotating the operation ring 6, the movable lens group 1 can be moved back and forth in the optical axis direction.

FIG. 2 shows a view seen from the optical axis direction of FIG.
Although the lens holding member 2 is held by the elastic disc as shown in FIG. 2, the elastic disc receives the force of pushing the lens holding member by the surface cam dispersed in its inner diameter and deforms into a conical shape. At this time, since only a force perpendicular to the surface of the elastic disk is applied, the center of the disk does not change and the optical axis of the lens group does not decenter. Also, since the lens holding member is pushed by the symmetrically arranged cam followers, it moves in parallel,
No tilt of the optical axis of the lens group occurs. Furthermore, since the present embodiment has a simple structure, it can be made compact and lightweight, and can be manufactured at low cost.

As described above, according to this embodiment, it is possible to realize a compact and lightweight lens moving mechanism in which the optical axis of the lens group is not decentered and does not tilt at low cost.

In this embodiment, the elastic disk is shown in FIG.
Although the above donut shape is shown, the same effect can be obtained by using the elastic disk 9 having one or more through holes 10 as shown in FIG. 2 (B). However, in this case, the shape and position of the through hole 10 of the elastic disk 9 must be symmetrical with respect to the position of the cam follower 8 that pushes the lens holding member 2 and the optical axis center. This is because when the lens holding member 2 is pushed, the elastic disk 9 is deformed symmetrically when viewed from the cam follower 8 when the cam follower is located at a symmetrical position on the line XX in FIG. 2B. Then, the lens holding member 2 moves without tilting, but if the cam follower 8 is located at an asymmetrical position as on the ZZ line, the elastic disk 9 is asymmetrically deformed, so that the lens holding member 2 tilts. This is because it will end up.

Further, in this embodiment, the lens barrel and the elastic disk are constructed as separate parts, but it is easily inferred that the same function and effect can be obtained even if they are integrally molded.

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, the members 1 to 4 are the same as those in the first embodiment and have the same configuration, so the description thereof is omitted.
Reference numeral 11 denotes a ring-shaped plate, and two pin members 12 having sharp tips are attached to one surface of the plate at symmetrical positions with respect to the center of the optical axis. At the position, a conical hole 13 and a V-shaped groove 14 are machined. However, the positions of the conical hole 13 and the V-shaped groove 14 are 180 °.
It is assumed to be off. The tip of the pin member 12 is in contact with the end surface of the lens holding member 2. In addition, FIG.
Shows the main part of the lens seen from above, and FIG. 3B shows the main parts seen from the side.

A conical hole 15 is formed on the wall surface of the fixing portion 3 facing the conical hole 13, and between the conical holes 13 and 15.
The ball member 16 is sandwiched. Further, a through hole 17 is provided on the wall surface of the fixed portion 3 facing the V-shaped groove 14. A ball member 18 is fitted into the through hole 17 so as to project to both sides of the hole 17. One side of the ball 18 is fitted into the V-shaped groove 14, and the opposite side is in contact with the cam surface of the cam member 19. The cam member 19 is rotatably supported with respect to the fixed portion 3, and can be rotated manually or electrically by a motor or the like.

A disc 20 having a slit is attached so as to rotate in synchronization with the cam member 19. Reference numeral 21 is a photo interrupter, which is arranged so as to sandwich the disk 20, and detects when the slit of 20 passes between 21 when the cam member 19 and the disk 20 rotate.

When the cam member 19 is rotated manually or electrically in such a structure, as shown in FIG.
The sphere member 18 is pushed by the cam surface of, and moves in the through hole 17 toward the ring-shaped plate 11, and pushes the ring-shaped plate 11. The plate 11 moves in the direction perpendicular to the optical axis by the effect of the spherical member 16 sandwiched between the conical holes of the opposing grooves 13 and 15 and the spherical member 16 fitted into the V-shaped groove 14 and the through hole 17. Is regulated, so that it is inclined toward the lens holding member 2 side with 16 as a fulcrum. Then, the pin member 12 pushes the lens holding member 2, and the holding member moves in the optical axis direction.

On the other hand, when the cam member 19 is reversed to reduce the displacement of the cam surface contacting the spherical member 18, the lens holding member 2 is driven by the elastic force of the elastic disc 4 as in the first embodiment. Moves in the opposite direction.

As described above, also according to the second embodiment, a lens moving mechanism using an elastic disk can be obtained, and its effect is the first.
It is similar to the embodiment.

In particular, in the second embodiment, since the ring-shaped plate 11 for pushing the lens holding member 2 tilts about the sphere member 16 as a fulcrum, the lever member is displaced by pushing the holding member 2 at the position of the pin member 12. The ratio of the amount of displacement to the amount of displacement given to the ring-shaped plate 11 from the cam member 19 via the spherical member 18 is the distance from the spherical member 16 serving as a fulcrum to the pin member 12 and the spherical member 18
Equal to the ratio of the distances. That is, the displacement amount of the cam increases by the distance ratio times the lens movement amount. As a result, when you want to move the lens group by a very small amount, the effect of cam processing error is less than when the cam displacement and lens group movement amount are the same, and cam processing is easier and lens position accuracy is better. The effect of improving is also obtained.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the ring-shaped plate 11 of the second embodiment shown in FIGS. 3 and 4 is used.
Instead of the elastic plate 31, a fulcrum is fixed to the fixing portion 3 with a screw 32. However, for convenience of illustration, the ball member 18 is changed to a pin member 33 having a sharp tip, but both have the same role. Other,
Members having the same numbers as in FIGS. 3 and 4 are the same as those in the second embodiment and have the same configuration.

In the figure, when the cam member 19 rotates, the pin 33 moves along with the displacement of the cam, and the elastic plate 31 is moved.
Is pressed. When the elastic plate 31 is pushed, the elastic plate 31 is deformed around the fixing portion of the screw 32 as shown in FIG. At this time, the pin member 12 attached to the elastic plate 31 is also pushed out to the lens holding member 2 side, and hence the lens group 1 is moved back and forth in the same manner as in the second embodiment.

The effect of the third embodiment is the same as that of the second embodiment, but in particular, in this embodiment, the elastic plate 31 is deformed, and the displacement amount is higher than the distance from the fixed portion by 32. Since it is a function, the ratio of the displacement of the position of the pin member 12 to the displacement given at the position of the cam member 19 is smaller than that in the second embodiment in which the displacement amount is a linear function of the distance from the fulcrum. That is, when the lens groups are moved by the same amount, the displacement amount of the cam is larger in the third embodiment than in the second embodiment if the dimensional relationship is the same. This allows
When the lens group is moved by a small amount, the processing of the cam is facilitated, and the effect of improving the accuracy of the lens position is further increased.

FIGS. 6 to 8 show the cam members for moving the lenses in the first to third embodiments, respectively, which are changed to feed screws.

First, referring to FIG. 6, in the first embodiment, the cam member 5 of FIG. 1 is changed to a ring member 41 having a screw on the outer circumference, and the cam member 5 is engaged with a female screw machined on the inner diameter of the fixing portion 3 to feed it. It is a screw. In this configuration, when the operation ring 6 is rotated, 41 is rotated via the pin member 7, and 41 is moved in the optical axis direction by the effect of the feed screw,
The lens group 1 is moved by pushing the lens barrel 2.

Next, FIG. 7 shows a second embodiment in which the cam member is changed to a feed screw. In FIG.
2 is a male screw of a feed screw, 43 is a female screw, and 42 is connected to an output shaft of a motor 44. Reference numeral 45 denotes a pin member attached to the female screw 43, which is fitted in an elongated hole provided in the fixing portion 3 so that the female screw 43 can move straight in the axial direction without rotating. Reference numeral 46 denotes a pin member having a sharp tip, which is attached to the female screw 43, and is a V of the ring-shaped plate 11.
It fits into the groove 14 and pushes 11. In this configuration, when the male screw 42 is rotated, the female screw 43 moves straight and pushes 11, so that the lens group 1 is moved in the same manner as in the second embodiment.

In FIG. 8, the cam member of the third embodiment is replaced with a feed screw, in which 43 female threads are integrally formed with 31 elastic plates. As a result, when the male screw 42 rotates, the displacement is directly given to the lens 31, and the lens group 1 can be moved as in the third embodiment.

As described above, in the first to third embodiments, even if the lens moving cam member is changed to the feed screw,
Similarly, the lens group can be moved, and the same effect can be obtained.

(Other Embodiments) FIG. 9 shows an example in which a plurality of elastic disks 4 for holding the lens barrel 2 are used in the second embodiment. According to the present embodiment, when held by one elastic disk 4, when the weight of the moving lens group 1 or the lens barrel 2 is heavy, or when the moving lens group 1 has a long overall length in the optical axis direction. The problem that the position of the lens barrel 2 held is likely to be unstable is solved. This has the same effect in the other embodiments described above.

FIGS. 10 and 11 show an example in which the lens moving mechanism according to the present invention is mounted on a photographing lens device and is used in a device for performing focus detection by slightly moving the lens group in the optical axis direction. Further, FIG. 10B shows an example in which the photographing lens device equipped with the lens moving mechanism according to the present invention is attached to a camera.

FIG. 11 is a block diagram when the lens moving mechanism of the present invention is used in a focus detection device of a lens device having an automatic focus adjustment function.

In FIG. 11, reference numeral 51 is a focus lens group for focusing, 52 is a zoom lens group for zooming, 53 is a diaphragm section for adjusting exposure, and 54 is a lens group that makes a minute movement in the optical axis direction. , 55 are lens moving mechanisms for moving the lens group 54 in the optical axis direction, and the lens moving mechanism according to FIG. 3 of the present embodiment is adopted in this portion. Further, reference numeral 56 is a drive unit for driving the lens moving mechanism 55, 57 is a relay lens group having an image forming action, and 58
Is a drive unit for driving the focus lens 51. Reference numeral 59 is an image pickup device, 60 is a control unit that controls the drive units 56 and 58 to operate the automatic focus adjustment function, and 61 is a circuit that executes control of the entire camera.

In the configuration of FIG. 11, the lens group 54 is
Even if it is moved slightly in the optical axis direction, the image magnification hardly changes and only the focus is blurred. Therefore, when the driving unit 56 slightly moves the lens group 54 in the optical axis direction, the focal position on the image pickup surface of the image pickup device 59 changes slightly, which can be detected as a change in the video signal. This is sent to the circuit 61 on the camera side for signal processing, the amount and direction of defocusing are calculated, and the result is output to the control unit 60. The control unit 60 outputs a drive signal according to the amount and direction of the out-of-focus, and the drive unit 58 causes the focus lens 5 to move.
By driving 1, automatic focus adjustment can be performed.

In this automatic focus adjustment method, the focus is out of focus due to the movement of the lens group to be wobbled. Therefore, the image signal does not change in the lens apparatus for photographing, particularly in the TV and video lens apparatuses that handle moving images. It is necessary to suppress the blurring within a detectable range and to the extent that it is visually unnoticeable. For this reason, the wobbling lens group must move with a very small moving amount, with high accuracy, and at high speed. However, in the case where the lens holding member is tilted due to the fitting gap as in the conventional lens moving mechanism, even if the lens is slightly moved, the tilt changes but does not move in the optical axis direction. Therefore, it cannot be moved accurately. On the other hand, according to the lens moving mechanism of the present invention, since the lens group can be moved without tilting, it is possible to move the lens group with a small amount of movement with high precision. Since the influence of the processing accuracy of is reduced, the accuracy is further improved. Further, unlike the conventional fitting method, the moving part is light in weight, so that it can be moved at high speed.

As described above, the lens moving mechanism of the present invention is suitable for use in the focus detection device of the above-described lens device with an automatic focus adjustment function, which makes it possible to achieve extremely high precision and high speed. It is possible to realize a lens device with a simple automatic focus adjustment function.

[0036]

As described above, according to the present invention,
It is possible to obtain a lens moving mechanism that is less likely to cause deterioration in optical performance due to decentering or tilting of the moving lens group, and that is small, lightweight, and inexpensive.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a lens moving mechanism according to the present invention.

FIG. 2 is a front view of the lens moving mechanism of FIG.

FIG. 3 is a diagram showing a second embodiment of the lens moving mechanism according to the present invention.

FIG. 4 is a diagram showing a state where a lens is moved by the lens moving mechanism of FIG.

FIG. 5 is a diagram showing a lens moving mechanism according to a third embodiment of the present invention.

FIG. 6 is a view showing a fourth embodiment of the lens moving mechanism according to the present invention.

FIG. 7 is a view showing a fifth embodiment of the lens moving mechanism according to the present invention.

FIG. 8 is a diagram showing a sixth embodiment of the lens moving mechanism according to the present invention.

FIG. 9 is a view showing a structure for holding another mode of the lens moving mechanism according to the present invention.

FIG. 10 is a diagram showing a state in which a lens moving mechanism according to the present invention is mounted on a camera.

FIG. 11 is a block diagram of the entire lens control according to the present invention.

FIG. 12 is a view showing a conventional lens moving mechanism.

FIG. 13 is a view showing a conventional lens moving mechanism.

Claims (2)

[Claims] 1. A lens, characterized in that a holding member for holding the lens is held by a disk-shaped elastic member with respect to the outer cylinder, and the holding member is pressed in the optical axis direction by a pressing member. Moving mechanism. 2. The lens moving mechanism according to claim 1, wherein the elastic member is a metallic thin film plate.