JP2021135432A - Lens device and imaging device - Google Patents

Abstract

To provide a lens device advantageous for adjusting the driving load of an optical member.SOLUTION: The lens device includes: a movable optical member; a driving unit for driving the optical member; a detection unit for detecting a driving current of the driving unit; a load generation unit for generating a second load to add to a first load as a driving load of the optical member; and a control unit for controlling the load generation unit on the basis of the driving current.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lens device and an imaging device.

The lens device used for image photographing (imaging device) has a movable optical member such as a zoom lens group and a focus lens group. Further, the optical member can be moved by a command from a camera (imaging device main body) to which the lens device is connected or by operating various operating members. The lens device is required to have high image quality and high magnification, and accordingly, it is necessary to increase the weight and the number of lens groups, and to coordinately drive a plurality of lens groups in a complicated trajectory by a cam mechanism.

However, when the attitude (the angle formed by the optical axis with respect to the horizontal plane, the attitude angle and the elevation / depression angle) and temperature of such a lens device fluctuate, the influence of gravity on the lens group and the change in the viscosity of the grease applied to the cam mechanism The load (drive load) required to move the lens group changes due to such factors. This drive load can also change depending on the position of the lens group.

When the magnitude of the drive load is zero or near zero, the drive control of the lens group tends to be unstable. Patent Document 1 discloses that it has a drive load adjusting means for increasing the drive load when the drive load of the movable optical member is smaller than the threshold value.

JP-A-2019-3065

The lens device of Patent Document 1 has a table showing the relationship between the position of the optical member and the driving load. It is difficult for the table to respond to individual differences in the lens device, changes in the environment, and changes over time. An object of the present invention is, for example, to provide a lens device that is advantageous for adjusting a driving load of an optical member.

In order to achieve the above object, the lens device of the present invention includes a movable optical member, a drive unit for driving the optical member, a detection unit for detecting a drive current of the drive unit, and a drive load of the optical member. It is characterized by having a load generation unit that generates a second load to be added to the first load, and a control unit that controls the load generation unit based on the drive current detected by the detection unit. do.

According to the present invention, for example, it is possible to provide a lens device that is advantageous for adjusting the driving load of an optical member.

It is a block diagram which shows the structure of the lens apparatus in Example 1. FIG. It is a figure explaining the control unstable region in Example 1. FIG. It is a figure which showed the current value of the motor and the drive load adjustment amount in Example 1. FIG. It is a flowchart which showed the flow of the drive load adjustment process in Example 1. FIG. It is a figure explaining the control unstable region in Example 2. FIG. It is a figure which showed the current value of the motor and the drive load adjustment amount in Example 2. FIG.

FIG. 1 shows the configuration of a lens device according to an embodiment of the present invention. The lens device 100 of this embodiment constitutes an image pickup device together with a camera device 200 to which the lens device 100 can be attached and detached.

The lens device 100 detects the positions of the CPU (control unit) 101, which is a control means, the zoom cam cylinder 102, the variator lens 103, the compensator lens 104, and the zoom cam cylinder 102, which are zoom movable parts (movable optical members). Includes part 105.

Further, a motor 106 (driving unit) for driving the zoom cam cylinder 102, a load generating unit 107 for generating a load required for driving the zoom cam cylinder 102 (hereinafter referred to as a driving load), and a current detecting unit. It is composed of 108 (detection unit).

The position detection unit 105 detects the position of the zoom cam cylinder 102, and is, for example, an encoder.
The motor 106 is an actuator for rotationally driving the zoom cam cylinder 102, and is, for example, a DC motor. The motor 106 engages with the zoom cam cylinder 102 by a gear train or the like, and rotationally drives the zoom cam cylinder 102 by a drive signal from the CPU 101. When the zoom cam cylinder 102 rotates, the variator lens 103 and the compensator lens 104 move back and forth along the cam groove of the zoom cam cylinder 102 in the optical axis direction, and a scaling operation is performed.

The load generation unit 107 has a mechanism that physically applies a drive load to the rotation of the zoom cam cylinder 102 by a control signal from the CPU 101. The load generation unit 107 is a device capable of changing the drive load by control, for example, a device using a magnetically viscous fluid. The ferrofluid is a member in which when a voltage is applied, a magnetic force is generated by a coil formed inside according to the applied voltage, and the viscosity of the ferrofluid changes by changing the magnetic force. The load generation unit 107 can change the drive load with respect to the rotation of the zoom cam cylinder 102 by controlling the voltage applied to the ferrofluid based on the drive load adjustment value by the CPU 101.

In the present embodiment, the load generation unit 107 is a device using a magnetic viscous fluid, but any device may be used as long as it is a device capable of changing the drive load by control.

The current detection unit 108 can detect the current flowing through the motor 106. For the current flowing through the motor 106 in the current detection unit 108, for example, the potential difference between both ends of the current detection resistor R1 is detected by a differential amplifier circuit composed of resistors R1 to R3 and an operational amplifier and input to the CPU 101. It is obtained by dividing the detected potential difference by the current detection resistor R1. The magnitude of the drive load of the zoom cam cylinder 102 is a value proportional to the current value of the motor 106 detected by the current detection unit 108. Therefore, by detecting the current value of the motor 106, it is possible to know the magnitude of the drive load required to move the zoom cam cylinder 102.

Further, as a movable optical member, the lens device 100 includes a zoom movable portion, a focus movable portion for adjusting the focus (not shown), and an iris movable portion for adjusting the amount of light.

The camera device 200 is a device that captures an image formed by the lens device 100 with the image sensor 201 and converts it into video data. The video data is recorded by a recording device or output to an external device.

FIG. 2 shows an example of fluctuation characteristics of the drive load (first load) of the zoom cam cylinder 102. The horizontal axis is the rotation angle of the zoom cam cylinder 102, the left side of the drawing is the wide angle end side, and the right side of the drawing is the telephoto end side. The closer to both ends, the heavier the drive load, and the closer to the center, the smaller the drive load. In the colored region of FIG. 2 where the drive load is small and the value is near zero, the drive control becomes unstable.

FIG. 3 is a diagram showing the relationship between the drive current when the drive load of the zoom cam cylinder 102 in this embodiment is adjusted and the adjustment amount of the drive load.

The graph shown in FIG. 3A is a drive current value when the drive load is not adjusted by the load generation unit 107. The horizontal axis is the rotation angle of the zoom cam cylinder 102, and the vertical axis is the current value of the motor 106 detected by the current detection unit 108. The colored region of FIG. 3A is a region of the current value corresponding to the region of the drive load in which the drive control of FIG. 2 becomes unstable. A current value slightly larger than the colored region is shown by a broken line in FIG. 3A as a current lower limit value (first threshold value).

FIG. 3B shows the current value when the drive load is adjusted by the load generation unit 107, and FIG. 3C shows the adjustment amount of the drive load (load adjustment amount, second) by the load generation unit 107. Load) is shown. The vertical axis of FIG. 3B is the current value, and the vertical axis of FIG. 3C is the load adjustment amount. When the current detection value becomes less than the current lower limit value, the load generation unit 107 adds a drive load.

Further, when the current detection value becomes larger than the lower limit value while the drive load is applied by the load generation unit 107, the drive load is reduced. Here, the drive load is reduced when the current detection value becomes larger than the current lower limit value, but the drive load is reduced when the value slightly larger than the lower limit value (lower limit value + α (α> 0)) is exceeded. The control may be stabilized.

By applying a drive load when the current detection value is less than the current lower limit value, it is possible to prevent the control from entering an unstable colored region and enable stable drive control. Further, when the current detection value becomes larger than the lower limit value while the drive load is applied, the power of the load generation unit 107 is not wasted by reducing the drive load.

When the drive load torque is applied and the current detection value exceeds a value slightly larger than the current lower limit value, the drive load may be reduced for more stable control, so that the current detection value is the current lower limit value. When it becomes larger than the second threshold value (lower limit value + α (α ≧ 0)) which is equal to or more than the value (first threshold value or more), the effect of the present invention can be enjoyed by controlling the drive load torque to be reduced.

FIG. 4 is a flowchart showing the flow of the load adjustment process in this embodiment. First, in step S10, the current detection unit 108 detects the current value of the motor 106. In step S11, it is determined whether or not the current detection value is less than the current lower limit value, and if it is less than the lower limit value, the drive load addition amount corresponding to the current value is calculated in step S12.

The drive load addition amount is calculated as a value corresponding to the difference between the current detection value and the current lower limit value. However, when the current value fluctuates abruptly, the difference between the current detection value and the current lower limit value becomes large, so that the drive load addition amount also becomes a large value. If a large drive load is added with one control command, it may affect the drive control. Therefore, control such as setting an upper limit on the drive load addition amount and gradually increasing the drive load with multiple commands is performed. You may go. In step S13, the drive load addition amount calculated in step S12 is output to the load generation unit 107, and the process ends.

If the current detection value is not less than the lower limit value in step S11, the load generation unit 107 determines in step S14 whether or not the drive load is being added. If the drive load is not being added, the process ends.

When the drive load is being added, in step 15, it is determined whether or not the current detection value is larger than (lower limit value + α (α> 0)). When the current detection value is (lower limit value + α) or less, the process ends without changing the drive load adjustment amount. If the current detection value is larger than (lower limit value + α), the subtraction amount of the drive load addition amount is calculated according to the current value in step S16.

The subtraction amount is, for example, a value such that the current value of the motor 106 when the reduced drive load addition amount is applied is smaller than (lower limit value + α) based on the difference between the current detection value and (lower limit value + α). Calculate as. In step S17, the drive load subtraction amount calculated in step S16 is output to the load generation unit 107, and the process ends.

When the zoom cam cylinder 102 is stopped, the current value may decrease regardless of the drive load of the zoom cam cylinder 102 itself (regardless of the rotation position of the zoom cam cylinder 102). When stopped, the control does not become unstable even if the current value becomes less than the current lower limit value. Therefore, when stopped, the value of the drive load output from the load generation unit 107 may be controlled so as not to change. In order to determine the stopped state of the zoom cam cylinder 102, for example, it may be confirmed that the value of the position of the zoom cam cylinder 102 detected by the position detection unit 105 does not fluctuate.

Further, during acceleration and deceleration of the zoom cam cylinder 102, the fluctuation of the current value of the motor 106 becomes large, so that the fluctuation of the drive load adjustment amount also becomes large, and the control may become unstable. Therefore, during acceleration and deceleration, the value of the drive load output from the load generation unit 107 may be controlled so as not to change. Whether it is accelerating or decelerating can be determined by checking the rate of change in speed calculated by differentiating the position of the zoom cam cylinder 102 detected by the position detection unit 105.

As described above, the drive load is adjusted by the load generation unit 107. In this embodiment, the drive load is adjusted based on the current detection value, so that even if there are individual differences in the movable optical member, environmental changes, or changes over time, the optimum drive load can be adjusted according to the changes. Is possible, and the stability of control can be improved.

The same components as those described in the first embodiment are indicated by the same reference numerals, and the description thereof will be omitted.
In the first embodiment, the drive load of the zoom cam cylinder 102 has been described as a value in the positive direction regardless of the rotation position, but the drive load may have a value in the negative direction depending on the rotation position. The drive control becomes unstable when the drive load is small as an absolute value (near zero), and this region (control unstable region) is shown by the colored region of FIG.

Therefore, when the absolute value of the drive load is equal to or greater than the lower limit value in the drive load in the negative direction, stable drive control is possible without adjusting the drive load. Therefore, the drive load may be adjusted when the absolute value of the drive current is less than the lower limit value.

FIG. 6 shows the relationship between the drive current and the adjustment amount of the drive load when the drive load is adjusted when the absolute value of the drive current is less than the lower limit value.

The graph shown in FIG. 6A is a drive current value when the drive load is not adjusted by the load generation unit 107. The drive load fluctuation characteristic of the zoom cam cylinder 102 in this embodiment is different from that in the first embodiment, and the drive load has a negative value on the telephoto end side. As a result, the value of the drive current, which is proportional to the drive load, also becomes a negative value on the telephoto end side.

FIG. 6B shows the current value when the drive load is adjusted by the load generation unit 107. FIG. 6C shows the amount of adjustment of the drive load by the load generation unit 107. The vertical axis of FIG. 6B is the current value corresponding to the drive load, and the vertical axis of FIG. 6C is the load adjustment amount. When the absolute value of the current detection value becomes less than the current lower limit value, the load generation unit 107 increases the drive load. As a result, it is possible to prevent the current value (or the value of the drive load) from becoming an unstable region in both the positive direction and the negative direction, and stable control becomes possible.

The broken line in FIG. 6C shows the upper limit of the adjustment amount of the drive load for which the load is adjusted. The upper limit value (third threshold value) of the adjustment amount of the drive load is set to, for example, the amount of the drive load corresponding to increasing the current amount twice the lower limit value of the current. That is, the adjustment amount of the drive load is adjusted so as to take a value equal to or less than the amount of the drive load (below the third threshold value) corresponding to increasing the current amount twice the lower limit value of the current, for example.

In this case, even if the adjustment amount (addition amount) of the drive load is set to zero at the timing when the adjustment amount of the drive load exceeds the upper limit value, the current value enters the stable region in the negative direction. Therefore, when the adjustment amount of the drive load exceeds the upper limit value, stable control is possible without adding the drive load, so that the adjustment amount of the drive load output from the load generation unit 107 is reduced.

Further, when the current value becomes larger than the lower limit value shown in the positive direction in FIG. 6B in the state where the drive load is added, the control is stable, so that the adjustment amount of the drive load is reduced. When the control enters a stable region, the power consumption of the load generation unit 107 can be reduced by reducing the adjustment amount of the drive load.

In the illustrated embodiment, the application to the zoom lens group as the movable optical member has been illustrated and described, but the present invention is not limited to this, and can be applied to the focus lens group, the aperture diaphragm, and the like. ..

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

100 ・ ・ ・ ・ Lens device 102 ・ ・ ・ ・ Zoom cam cylinder (optical member)
103 ・ ・ ・ ・ Variator lens (optical member)
104 ・ ・ ・ ・ Compensator lens (optical member)
106 ・ ・ ・ ・ Motor (drive unit)
107 ・ ・ ・ ・ Load generation unit 108 ・ ・ ・ ・ Current detection unit (detection unit)

Claims (10)

Movable optics and
A drive unit that drives the optical member and
A detection unit that detects the drive current of the drive unit,
A load generating unit that generates a second load to be added to the first load as a driving load of the optical member, and a load generating unit.
A control unit that controls the load generation unit based on the drive current detected by the detection unit, and a control unit that controls the load generation unit.
A lens device characterized by having. The first aspect of claim 1, wherein the control unit causes the load generation unit to generate the second load when the absolute value of the drive current detected by the detection unit is smaller than the first threshold value. Lens device. When the absolute value of the drive current detected by the detection unit is larger than the second threshold value equal to or higher than the first threshold value in the state where the load generation unit generates the second load. The lens device according to claim 2, wherein the load generating unit reduces the second load. The lens device according to claim 2 or 3, wherein the control unit sets the second load generated by the load generation unit to be equal to or less than a third threshold value. The lens device according to claim 4, wherein the control unit sets the second load generated by the load generation unit to zero when the first load exceeds the third threshold value. The lens device according to claim 4 or 5, wherein the third threshold value is a value of the driving load corresponding to twice the first threshold value. The lens according to any one of claims 1 to 6, wherein the control unit does not change the second load to the load generation unit when the optical member is stopped. Device. The control unit according to any one of claims 1 to 7, wherein the second load is not changed by the load generation unit when the optical member is accelerating or decelerating. Lens device. The lens device according to any one of claims 1 to 8, wherein the optical member includes at least one of a focus lens group, a zoom lens group, and an aperture diaphragm. The lens device according to any one of claims 1 to 9.
An image sensor that captures the image formed by the lens device,
An imaging device characterized by having.

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