JPH0772367A - Lens driving device - Google Patents

Abstract

PURPOSE:To position a cam member for correction invariably with high precision irrelevantly to the position of a lens by storing correction quantities of the cam member for correction at necessary intervals and driving the cam member for correction according to the correction quantities. CONSTITUTION:A main controller 61 generates a signal S1 of crank position information at the point of time each time a crank 10 rotates by a specific angle and a correction quantity calculating device 62 calculates the correction quantity of the cam plate 14 for correction. A correction quantity storage device 63 stores correction quantity data on the cam plate 14 for connection the positions of a movable lens group and temperatures. Then the correction quantity calculating device 62 reads the corresponding correction quantity of the plate 14 for connection out of the correction quantity storage device 63 on the basis of the signal S1 and temperature information and the correction quantity calculating device 62 calculates the driving quantity of the cam plate for connection from a signal S3 of the correction quantity data and sends a driving signal to a correction cam plate driving circuit 64 to drive a correction cam plate driving actuator (stepping motor) 53, thereby determining the position of the cam plate 14 for connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for driving a plurality of movable lens groups in association with each other.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view showing the basic structure of a lens driving device (Japanese Patent Application No. 4-333165) already proposed by the present applicant. Movable lens group 1 and movable lens group 2
Is an optical system that performs an operation such as zooming or focusing by moving along the optical axis according to a predetermined relationship. The movable lens group 1 and the movable lens group 2 can be moved in the optical axis direction by slider portions 1a and 2a with respect to a guide shaft 5 fixed in parallel to the optical axis on a support plate 3 that is a base of the lens barrel. It is supported. Further, the movable lens group 1 and the movable lens group 2 are engaged with the guide shaft 4 so as to limit the rotation around the guide shaft 5. Therefore, the movable lens group 1 and the movable lens group 2 can move in the optical axis direction with respect to the guide shaft 4 and the guide shaft 5, but cannot move in the rotation direction around the guide shaft 5.

The movable lens group 1 is driven by using a slider crank mechanism including a slider portion 1a, a crank 10, a connecting member 11 and the like. The crank 10 has a rotating shaft integrated with the shaft 41 of the motor 42.
Rotates according to the rotation of the motor shaft 41. The motor 42 is fixed to the support plate 3 by a member (not shown). The crank 10 is rotatably connected to the connecting member 11 via a connecting member 22, and the connecting member 11 is rotatably connected to the movable lens group 1 via a connecting member 21. Therefore, when the motor shaft 41 rotates, the slider portion 1a slides on the guide shaft 5 via the crank 10 and the connecting member 11, so that the movable lens group 1 moves in the optical axis direction.

The correction lever 13 has a connecting member 2 at one end.
3 is rotatably connected to the slider portion 2a of the movable lens group 2, and a cam follower 26 is fixed to the other end. The cam follower 26 is movable along the cam groove 14a of the correcting cam plate 14. The correction lever 13 is rotatably connected to one end of the connecting member 12 by a connecting member 24, and the crank 10 is rotatably connected to the other end of the connecting member 12 by a connecting member 25.
Therefore, also on the movable lens group 2 side, the slider portion 2a, the connecting member 12, and the crank 10 constitute a slider crank mechanism.

As described above, the movable lens group 2 is movable only in the optical axis direction, and the correction cam plate 14 is also fixed to the support plate 3 via the correction cam fixing plate 8.
The movement of the correction lever 13 is restricted, and the correction lever 13
The position of the movable lens group 2 is determined by determining the position of a certain point above. That is, as the crank 10 rotates, the position of the connecting member 25, which is one of the fulcrums of the connecting member 12, is determined, and since the correction lever 13 and the connecting member 12 are linked by the connecting member 24,
Since the position of the correction lever 13 is determined, the position of the movable lens group 2 is determined. That is, in this lens driving device, the connecting member 12 plays a role of approximately positioning the position of the movable lens group 2 with respect to an accurate set position,
Further, the correction lever 13 is set with a movement amount for correction by the movement of the cam follower 26 that engages with the correction cam plate 14, so that the movable lens group 2 can move to the regular position. To do.

The correction cam plate 14 is movable with respect to the correction cam fixing plate 8 formed integrally with the support plate 3, and by adjusting the position of the correction cam plate 14,
It was possible to correct the position of the movable lens group 2 with respect to the movable lens group 1 to correct the focal point movement or the like that occurs when the focal length of the lens system is changed.

[0007]

However, in the lens driving device described above, by adjusting the position of the correcting cam plate 14, errors due to machining errors of each member and variations in assembling work (hereinafter, these will be summarized as follows. Manufacturing error)
Can be corrected to some extent, but the degree of freedom for adjusting the correction cam plate 14 is X, Y in FIG.
Since it is only a combination of the movement in the direction and the rotation around θ, it is difficult to completely correct the manufacturing error in all the movable ranges.

Further, while the crank 10 moves from one end to the other end of the movable range, the movable lens group 2 is moved by the correction cam plate 14.
When the above-mentioned same portion is passed a plurality of times, that is, in the case of an optical system in which the movable lens group 2 reciprocates, there are a plurality of positions of the correction cam plate 14 for correcting manufacturing errors, and all of them are present. It was difficult to accurately correct the state of. Furthermore, when the movable lens group 2 reciprocates,
Since there are a plurality of approximation error correction amounts by the slider crank mechanism at the same cam position, it may not be possible to realize a mechanism capable of correcting lens positions within an allowable value at all of the plurality of positions.

Further, since the correction cam plate 14 is fixed after the assembly adjustment, it is difficult to deal with the dimensional change due to the temperature change of the use environment after the final adjustment. Furthermore, it is not easy to adjust the correction cam plate 14 within the permissible range over the entire driving range by combining the X and Y directions and the θ rotation.

An object of the present invention is to solve all of the above problems and to provide a lens driving device capable of highly accurate positioning regardless of the lens position.

[0011]

In order to solve the above-mentioned problems, the first solution means of the lens driving device according to the present invention comprises:
First and second movable lens groups, support means for movably supporting the first and second movable lens groups in the optical axis direction by the first and second slide members, and the first slide member And a first crank member connected to the first slide member via a first connecting member to form a slider crank mechanism, and to move the first movable lens group.
Moving means, driving means for driving the crank member to rotate, the second slide member and the second slide member, and the crank member connected to the second slide member via a second connecting member to form a slider crank mechanism. Then, the second moving unit that moves the second lens group to an approximate position and the driven member that engages with the second connecting member are driven by the correction cam member having a predetermined shape. A lens driving device including a correction unit that corrects the moving position of the second movable lens unit to a normal position, and stores a correction amount of the correction cam member corresponding to the position of the first movable lens unit. And a correction cam member driving unit that drives the correction cam member based on the correction amount stored in the correction amount storage unit.

A second solving means is the lens driving device according to the first solving means, wherein the correcting cam member driving means is
The correcting cam member is driven so as to slightly move the second movable lens group in the optical axis direction.

A third solving means is the lens driving device of the first solving means, further comprising a temperature detecting means for detecting the temperature of a use environment, and the correction amount storing means stores a correction amount for each temperature. The correction cam member drive means drives the correction cam member based on a correction amount corresponding to the temperature detected by the temperature detection means.

[0014]

According to the first solving means, the correction cam storing means can correct the position of the second movable lens group with respect to the position of the second movable lens group by the correction amount storing means. The correction amount can be stored for each required interval, and the correction cam member driving means can drive the correction cam member according to the correction amount. Further, when the second movable lens group passes through the same portion on the correction cam member a plurality of times while the crank member moves from one end to the other end of the movable range, that is, the second movable lens group reciprocates. In the case of the optical system as well, the correction amount corresponding to the position is read out from the correction amount storage means each time, and the correction cam member driving means can drive the correction cam member based on the correction amount. Therefore, high-precision positioning can always be performed regardless of the lens position.

According to the second solving means, the correcting cam member driving means can drive the correcting cam member so that the second movable lens group is slightly moved in the optical axis direction. For this reason, it becomes possible to drive the lens to generate the image signal necessary for the autofocus control of the lens.

According to the third solving means, the temperature is measured by the temperature detecting means and the correcting cam member driving means is used.
It is possible to drive the correction cam member based on the correction amount that provides the optimum value at that temperature. For this reason, the correction cam member can be driven even after the assembly adjustment, so that it is possible to cope with the dimensional change due to the temperature change of the use environment that occurs after the final adjustment.

[0017]

Embodiments will be described in more detail below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a lens driving device according to the present invention. It should be noted that parts having the same functions as those of the basic configuration shown in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted. In the lens drive device of this embodiment, the correction cam plate 14 is rotatably held by the holding member 8 fixed to the support base 3, and the correction cam plate drive device 50 moves the correction cam plate 14 for correction. It has a structure that allows it.

FIG. 2 is a front view showing the details of the correcting cam plate driving device of the embodiment shown in FIG. The correction cam plate 14 is
It is rotatably supported by the holding member 8 with the connecting member 51 as a fulcrum (see FIG. 1). Stepping motor 53
Is an actuator that drives the correction cam plate 14, and is supported by the support member 52 fixed to the holding member 8 at the portion of the rotary shaft 54. This rotary shaft 54 has
A male screw is formed, and the support member 52 has a rotating shaft 5
4 is formed with a female screw. Further, the stepping motor 53 is provided with a flange 55,
A rotation stopping shaft 56 is attached to the flange 55. The rotation stop shaft 56 is provided on the guide portion 5 of the support member 52.
The shaft 2a is movable in the axial direction of the rotary shaft 54, and is engaged with the shaft 2a so as not to rotate in the circumferential direction of the rotary shaft 54. Therefore, when the stepping motor 53 rotates, the rotary shaft 54 moves in the axial direction. Also, the holding member 8
A tension spring 57 is provided between the correction cam plate 14 and the correction cam plate 14, and the correction cam plate 14 is always pulled to the holding member 8 side by being biased by the tension spring 57. . Therefore, the correction cam plate 14 and the rotary shaft 5
The tip 54a of No. 4 is always in contact.

As described above, the rotary shaft 54 has the tip portion 54a.
Is in contact with the correction cam plate 14, and the correction cam plate 14
Is a in the figure as the tip 54a of the rotary shaft 54 moves.
Since it moves in the direction, the correction cam plate 14 can be moved to an arbitrary position within the movable range by controlling the rotation angle of the stepping motor 53.

Next, the operation of this embodiment will be described together with the control circuit. FIG. 3 is a block diagram showing a control circuit of an embodiment of the lens driving device according to the present invention. The main controller 61 is a device that controls the entire lens driving device of this embodiment. The lens position input device 66 is a device for inputting a position signal that determines the lens position, and its output is connected to the main control device 61. The main control device 61 sends a control signal to the crank drive circuit 67 based on the position signal from the lens position input device 66 to drive the crank drive actuator 42,
The crank 10 is rotated so that the crank angle corresponds to the determined lens position.

At this time, the main controller 61 determines that the crank 1
Every time 0 rotates by a predetermined angle, a signal S1 of crank position information at that time is generated and output to the correction amount calculation device 62. The correction amount calculation device 62 is for calculating the correction amount of the correction cam plate 14 based on signals from the main control device 61, the correction amount storage device 63, the temperature sensor 65, and the like.

The correction amount storage device 63 stores the correction amount data of the correction cam plate 14 necessary for correcting the manufacturing error for each position of the movable lens group 1 and each temperature. This correction amount data is obtained by measuring the deviation amount of the optical performance in each state and each temperature of the movable lens group 1 after the assembly adjustment of the lens barrel and correcting the deviation amount. The correction amount in the optical axis direction of the lens group 2 is obtained and converted into the drive amount of the correction cam plate 14 for performing the correction in the optical axis direction.

The correction amount calculation device 62 corrects the correction amount of the corresponding correction cam plate 14 based on the crank position information signal S1 input from the main control device 61 and the temperature information from the temperature sensor 65. It is read from the quantity storage device 63.
The correction amount calculation device 62 obtains the drive amount of the correction cam plate 14 based on the signal S3 of the read correction amount data, sends a drive signal to the correction cam plate drive circuit 64, and the correction cam plate drive actuator. (Stepping motor) 5
3 is driven, and the position of the correction cam plate 14 is determined.

In a video camera or the like, when autofocusing is performed, a specific lens group is slightly moved in the optical axis direction at a specific cycle, and image data when the movement is performed is processed to set the focus direction. It is often calculated.
Therefore, in the lens driving device according to the present embodiment, a signal is issued from the main control device 61 so that the movable lens group 2 makes a desired minute movement, whereby the correction cam plate 14 is minutely moved, and the movable lens is moved. I am trying to move group 2.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also included in the present invention. For example, although an example in which a stepping motor is used as the actuator that drives the correction cam plate 14 has been described, the same is true even if this is replaced with an actuator such as a servo mechanism using a DC motor, a linear motor, or a voice coil motor. The effect is obtained. Further, in this embodiment, the approximation error is corrected by the shape of the cam groove of the correction cam plate, and the manufacturing error is corrected by driving the cam plate. It is also possible to correct this by driving the correction cam plate by combining some or all of the approximation errors and the manufacturing error. In this case, it is possible to make the shape of the cam groove gentle or straight.

[0026]

As described in detail above, according to the first aspect, the correction cam member necessary for determining the position of the second movable lens group with respect to the position of the first movable lens group. The correction amount is stored for each required interval, and the correction cam member is driven according to the correction amount. Therefore, regardless of the lens position, highly accurate positioning can always be achieved. Further, when the second movable lens group passes through the same portion on the correction cam member a plurality of times while the crank member moves from one end to the other end of the movable range, that is, the second movable lens group reciprocates. Also in the case of the optical system, the correction amount of the manufacturing error and the approximation error corresponding to the position of the first movable lens group is read from the correction amount storage means each time, and the correction cam member is driven based on the correction amount. Therefore, there is an effect that the second movable lens group can be accurately positioned with respect to the first movable lens group.

According to the second aspect, since the correction cam member is driven so that the second movable lens group slightly moves in the optical axis direction, an image signal necessary for controlling the autofocus of the lens is produced. Therefore, there is an effect that it is possible to drive the lens.

According to the third aspect, it is possible to drive the correcting cam member even after the assembly and adjustment.
The dimensional change due to the temperature change of the use environment after the final adjustment can be dealt with by measuring the temperature by the temperature detecting means and calculating the correction amount to be the optimum value at that temperature. is there.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a lens driving device according to the present invention.

FIG. 2 is a front view showing details of a correction cam plate driving device of the embodiment of FIG.

FIG. 3 is a block diagram showing a control circuit of an embodiment of the lens driving device according to the present invention.

FIG. 4 is a perspective view showing a basic configuration of a lens driving device (Japanese Patent Application No. 4-333165) already proposed by the applicant.

[Explanation of symbols]

1, 2 movable lens group 3 support plate 4, 5 guide shaft 8 correction cam fixing plate 10 crank 11, 12 connecting member 13 correction lever 14 correction cam plate 21, 22, 23, 24, 25 connecting member 26 cam follower 50 correction cam plate drive device 51 connecting member 52 support member 53 correction cam plate actuator (stepping motor) 54 rotation shaft 55 flange 56 rotation stop shaft 57 tension spring 61 main control device 62 correction amount calculation device 63 correction amount storage device 64 correction Cam plate drive circuit 65 Temperature sensor 66 Lens position input device 67 Crank drive circuit

Claims (3)

[Claims] 1. A first and a second movable lens group, a support means for supporting the first and the second movable lens group by a first and a second slide member so as to be movable in an optical axis direction, A slider moving mechanism that includes a first slide member and a crank member that is connected to the first slide member through a first connecting member; and a first moving unit that moves the first movable lens group. A drive means for rotationally driving the crank member, the second slide member, and the second slide member connected to the crank member via a second connecting member to form a slider crank mechanism. The second moving unit that moves the second lens group to an approximate position and the driven member that engages with the second connecting member follow the correction cam member having a predetermined shape, so that the second movable unit is moved. Lens group A lens driving device including a correction unit that corrects a movement position to a normal position, the correction amount storage unit storing a correction amount of the correction cam member corresponding to a position of the first movable lens group, A lens driving device comprising: a correction cam member driving unit that drives the correction cam member based on the correction amount stored in the correction amount storage unit. 2. The lens driving device according to claim 1, wherein the correcting cam member driving unit drives the correcting cam member so as to slightly move the second movable lens group in the optical axis direction. A lens driving device characterized by: 3. The lens driving device according to claim 1, further comprising a temperature detecting unit that detects a temperature of a use environment, wherein the correction amount storage unit stores a correction amount for each temperature, The lens driving device, wherein the cam member driving means drives the correcting cam member based on a correction amount corresponding to the temperature detected by the temperature detecting means.