Diaphragm driving device, and lens device having the same

Abstract

To provide a diaphragm driving device that can improve the accuracy of the opening size of a diaphragm even under a plurality of conditions.SOLUTION: A diaphragm driving device has: a diaphragm blade member; a driving ring that is engaged with the diaphragm blade member and rotates to form the opening size of a diaphragm; a driving unit that drives the driving ring; and a control unit that controls the drive of the driving unit according to one of a first control pattern and a second control pattern. The absolute value of the difference between a deceleration speed at each position until the diaphragm blade member is stopped when the drive of the driving unit is controlled according to the first control pattern, and a deceleration speed at each position until the diaphragm blade member is stopped when the drive of the driving unit is controlled according to the second control pattern, is smaller than a first predetermined value.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an aperture drive device. [Background technology]

[0002] As digital cameras improve their continuous shooting performance, the number of continuous shots per unit time is increasing, and the brightness change between each shot is becoming more noticeable, so there is a demand for more accurate aperture diameter. Patent Document 1 discloses a configuration for improving the accuracy of the aperture diameter by creating a table of drive instruction values ​​for achieving a target aperture value from an actual measurement value, and controlling the aperture diameter based on the drive instruction values. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-113894 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, as lenses have become more powerful and sophisticated, the power consumed within the lens has increased due to an increase in the number of actuators used and the attachment of external adapters, making it necessary to address power saving. In the aperture drive device, not only normal drive but also various drives such as drives that support power saving are required. However, in the configuration of Patent Document 1, a table of drive instruction values ​​is created based on actual measured values ​​under specific conditions, so if conditions such as power are different, it may not be possible to guarantee the accuracy of the aperture opening diameter.

[0005] An object of the present invention is to provide an aperture drive device that can improve the accuracy of the aperture opening diameter under a variety of conditions. [Means for solving the problem]

[0006] An aperture drive device according to one aspect of the present invention comprises an aperture blade member, a drive ring that engages with the aperture blade member and rotates to form an aperture opening diameter, a drive unit that drives the drive ring, and a control unit that drives and controls the drive unit according to one of a first control pattern and a second control pattern, and is characterized in that the absolute value of the difference between the deceleration speed at each position leading to the aperture blade member stopping when the drive unit is driven and controlled according to the first control pattern and the deceleration speed at each position leading to the aperture blade member stopping when the drive unit is driven and controlled according to the second control pattern is smaller than a first predetermined value. Effect of the Invention

[0007] According to the present invention, it is possible to provide an aperture drive device that is capable of improving the accuracy of the aperture opening diameter even under a variety of conditions. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram of an imaging device according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 13 is a diagram showing a correction table. [Figure 4] 5A and 5B are diagrams illustrating acceleration and deceleration patterns during normal driving and power saving driving in the first embodiment. [Diagram 5] 11A and 11B are diagrams illustrating acceleration and deceleration patterns during normal driving and power saving driving in a conventional example. [Figure 6] FIG. 4 is a diagram showing locations where loads are generated by the aperture blades. [Figure 7] 6 is a diagram showing the difference in stopping position between normal driving and power saving driving using the acceleration / deceleration pattern in FIG. 5. FIG. [Figure 8] 13A and 13B are diagrams illustrating acceleration and deceleration patterns when the load caused by throttling is large. [Figure 9] 9 is a diagram showing the difference in stopping position between normal driving and power saving driving using the acceleration / deceleration pattern in FIG. 8. FIG. [Figure 10] 13A and 13B are diagrams illustrating acceleration and deceleration patterns during normal driving and high-speed driving in the second embodiment.

[0009] FIG. 1 is a diagram showing acceleration and deceleration patterns in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted. EXAMPLES

[0011] 1 is a block diagram of an imaging device 100 according to an embodiment of the present invention. The imaging device 100 is a camera system such as a single-lens reflex camera having a camera device 1 and a lens device 2 that is detachable from the camera device 1. However, the present invention is not limited to this, and can also be applied to an imaging device in which the camera body and the lens device are integrally configured.

[0012] The camera device 1 has an imaging element 8 such as a CMOS sensor or a CCD sensor. The imaging element 8 captures an image formed by the lens device 2. The lens device 2 has a lens group (imaging optical system) 3 and an aperture 4. An aperture drive unit 41 drives the aperture 4 via a stepping motor (drive unit) 411 (described later). A lens control unit (control unit) 6 issues a drive command to the aperture drive unit 41 based on the aperture value instructed by the camera control unit 7 and the drive conditions, drive pattern, and correction table 51 (shown in FIG. 3) related to the aperture 4 stored in the memory unit 5, and controls the drive of the stepping motor 411.

[0013] FIG. 2 is a configuration diagram of the diaphragm 4. The diaphragm 4 is an aperture mechanism that includes a stepping motor 411, a cover member 43, a drive ring 44, diaphragm blades (a plurality of diaphragm blade members) 42 that form an aperture opening diameter 42A, and a base member 45, and adjusts the amount of light that has passed through the lens group 3. The stepping motor 411 is connected to the cover member 43 by a screw 411B. The drive ring 44 and the stepping motor 411 are engaged with each other by a gear 411A (shown in FIG. 6) and a gear 44A. The drive ring 44 engages with a fitting protrusion of the cover member 43. Therefore, when the stepping motor 411 is driven, a force is transmitted to the drive ring 44, and the drive ring 44 rotates around the center of the opening of the cover member 43 as the axis of rotation. In addition, the diaphragm blades 42 have drive pins formed on both sides, and are engaged with holes 44B provided at equal intervals in the drive ring 44 and cams 45A provided at equal intervals in the base member 45, respectively. Therefore, when the drive ring 44 rotates, the diaphragm blades 42 rotate in cooperation with the cam 45A, varying the diaphragm opening diameter 42A. The base member 45 has a circular opening, and is connected to the cover member 43 with screws (not shown). The overlap amount of the diaphragm blades 42 also changes depending on the position of the diaphragm blades 42, and the load applied to the diaphragm driver 41 also changes. In general, the load is greater on the side with a larger aperture value, i.e., on the side where the overlap amount of the diaphragm blades 42 increases. The diaphragm driver 41 includes a stepping motor 411, and is controlled by the lens controller 6.

[0014] A method for generating the correction table 51 in FIG. 3 stored in the storage unit 5 will be described below. In the manufacturing stage, the aperture 4 measures the light quantity value (AV value) for each step. The measured AV value varies for each individual aperture 4, but since the measurement conditions such as voltage and acceleration / deceleration pattern are standardized to the conditions required for the lens device 2, the main cause is the variation in the parts and the aperture drive unit 41. Therefore, in order to eliminate this variation and improve the accuracy of the aperture aperture diameter for each individual, a step that is the closest AV value to each aperture value (Fno) is selected from the measured AV values, and a correction table is created. In addition to the correction table 51, the storage unit 5 also stores driving conditions such as applied voltage in normal driving, in which the accuracy of the aperture diameter described later is guaranteed to be within an allowable range, and in power-saving driving, in which power is limited compared to the normal driving, and the acceleration / deceleration pattern in each driving.

[0015] Note that 1Step indicates a pulse position at a 1-2 phase drive stop point of the stepping motor 411. The subsequent Steps indicate steps in the 1-2 phase drive. That is, 1Step is one step of 1-2 phase drive, and 4Step is four steps of 1-2 phase drive.

[0016] In recent years, the number of actuators in a lens device has increased with the improvement of the performance of the lens device. As a result, the power consumption in the lens device is on the rise, and power saving measures are required. In addition, as the lens device becomes more functional, the number of structures in which an external device such as an external power zoom adapter is attached to the lens device is increasing. In this case, the power for driving the external device is also squeezed from the lens device, and power saving measures are required. As a power saving measure for the aperture, a method of reducing the applied voltage is considered. However, reducing the applied voltage also reduces the torque of the stepping motor, and the torque of the stepping motor may be overwhelmed by the load associated with the opening and closing operation of the aperture blades, causing the stepping motor to lose synchronism.

[0017] Therefore, in this embodiment, the acceleration / deceleration pattern shown by the solid line in Fig. 4 is used during power-saving drive. Fig. 4 is a diagram showing the acceleration / deceleration pattern during normal drive (first control pattern) and the acceleration / deceleration pattern during power-saving drive (second control pattern). The horizontal axis in Fig. 4 represents Step, and the Step becomes larger toward the right, and the aperture 4 is narrowed to a small aperture state. The vertical axis in Fig. 4 represents the rotation speed of the stepping motor 411.

[0018] In this embodiment, the feature that the motor torque increases as the rotation speed of the stepping motor 411 decreases is utilized. Specifically, as shown by the solid line in Fig. 4, during power-saving drive, the maximum speed of the stepping motor 411 is decreased, and the acceleration is reduced to decrease the speed and increase the motor torque, resulting in an acceleration / deceleration pattern. This makes it possible to ensure a torque margin (a margin of torque generated by the motor relative to the load torque of the aperture blades 42 and the drive ring 44). In this way, during power-saving drive, the applied voltage is decreased compared to normal drive, but by adopting an acceleration / deceleration pattern different from that during normal drive, power saving is possible without losing synchronism.

[0019] In this embodiment, the deceleration steps of the acceleration / deceleration pattern are divided into region 1 and region 2. Region 1 is the region where the stepping motor 411 starts to decelerate, and is a region where a torque margin cannot be secured in power-saving drive with a lower voltage if the deceleration speed is set to the same as in normal drive. Region 2 is a region where the torque increases due to the low speed, and a torque margin can be secured even at the same deceleration speed as in normal drive. Therefore, the deceleration steps during power-saving drive are set to a speed at which a torque margin can be secured in region 1, and are set to the same deceleration speed as in normal drive in region 2. This makes it possible to realize the same stop position as in normal drive, as described later, without stepping out.

[0020] The reason why the deceleration speed is set to the same during power saving driving and during normal driving in region 2 in FIG. 4 will be described below.

[0021] Fig. 5 is a diagram showing acceleration / deceleration patterns during normal driving and during power-saving driving in a conventional example. In Fig. 5, the horizontal axis represents steps, and the vertical axis represents the rotation speed of stepping motor 411. The acceleration / deceleration pattern during power-saving driving shown by the solid line is a uniformly slower speed than the acceleration / deceleration pattern during normal driving shown by the dashed line.

[0022] Here, the stopping operation of the diaphragm 4 will be described with reference to FIG. 6. FIG. 6 is a diagram showing the location where the load is generated by the diaphragm blade 42. The diaphragm 4 decelerates so that the rotation speed of the stepping motor 411 becomes 0 at the aperture value Step instructed by the lens control unit 6. However, in reality, in the range indicated by the diagonal lines in FIG. 6, the diaphragm blades 42 overlap each other and generate frictional forces. These forces become a load on the driving of the stepping motor 411, and if the load is large, the diaphragm blade 42 stops before reaching the aperture diameter corresponding to the aperture value Step instructed by the lens control unit 6. On the other hand, if the load is small, the diaphragm blade 42 stops at a position narrower than the aperture diameter corresponding to the instructed aperture value Step. In this way, the stopping position of the diaphragm blade 42 is a position where the energy consumed by the frictional force of the diaphragm blade 42 and the kinetic energy of the diaphragm blade 42 before stopping are balanced.

[0023] 5, the kinetic energy of the diaphragm blades 42 before stopping differs between normal driving and power saving driving. Meanwhile, the load force such as friction between the diaphragm blades 42 is determined by the friction coefficient and the overlapping area of ​​the diaphragm blades 42, so it will be the same for the same diaphragm 4 in normal driving and power saving driving. Therefore, since the relationship between the kinetic energy of the diaphragm blades 42 and the load differs between normal driving and power saving driving, there will be a difference in the stopping position of the diaphragm blades 42.

[0024] FIG. 7 is a diagram showing the difference between the stop positions during normal driving and during power-saving driving using the acceleration / deceleration pattern of FIG. 5. In FIG. 7, the horizontal axis is Step, and the vertical axis is the difference between the AV values ​​when the normal driving and power-saving driving are stopped at the same Step. Here, the AV value measured at 20 Steps during power-saving driving subtracted from the AV value measured at 20 Steps during normal driving is 0.10 AV. The larger the AV value, the darker it is, and the more the aperture 4 is closed down. In other words, since the subtracted value is more positive and the AV value in power-saving driving is smaller, it indicates that the aperture blades 42 cannot be narrowed down even at the same Step position compared to normal driving. Here, the larger the Step, the larger the difference between the stop positions during normal driving and power-saving driving. As mentioned above, the larger the aperture value, the larger the overlap between the aperture blades 42 and the more energy is consumed. Therefore, in power-saving driving, where the rotation speed of the stepping motor 411 is slow and the kinetic energy of the aperture blades 42 before stopping is small, the aperture cannot be narrowed down compared to normal driving, and the difference is large. As described above, the correction table 51 of the drive instruction values ​​is generated based on the actual measurement values, but if the actual measurement values ​​(stop positions of the aperture blades 42) differ between normal driving and power saving driving, it is not possible to share the correction table 51. Therefore, it is necessary to prepare a correction table 51 for each driving condition such as normal driving and power saving driving, which increases the amount of data and the work time required to generate the correction table 51.

[0025] Therefore, in this embodiment, the deceleration speed of the stepping motor 411 is set to be the same in the normal driving and the power saving driving in the region 2. That is, the deceleration speed of the diaphragm blade 42 is set to be the same in the normal driving and the power saving driving in the region 2. Here, "same" includes not only the case where it is exactly the same, but also the case where it is substantially the same (almost the same). As a result, the relationship between the energy consumed by the frictional force of the diaphragm blade 42 and the kinetic energy of the diaphragm blade 42 before stopping becomes equal in the normal driving and the power saving driving, and the stopping position can be made the same. Ideally, it is preferable that the region 1 and the region 2 are switched near the middle of the deceleration region in the acceleration / deceleration pattern. As a result, by matching the deceleration speed in the normal driving and the power saving driving from an early stage, the relationship between the energy consumed by the frictional force of the diaphragm blade 42 and the kinetic energy of the diaphragm blade 42 can be matched, and the stopping position can be matched with higher accuracy. Also, if a torque margin can be secured, the speed may be matched not only during deceleration but also during acceleration. In this case, the driving time can be shortened.

[0026] On the other hand, in a large aperture 4, the size of the aperture blades 42 is large, so the sliding area between the aperture blades 42 also increases, and the load resistance also increases accordingly. In such an aperture 4, it is difficult to secure a torque margin, and the region 2 becomes small. However, as shown in FIG. 8, by matching the speed of one step before stopping in normal driving and in power-saving driving, the speed of the aperture blades 42 just before stopping can be made the same. This makes it possible to suppress the difference in the stopping position as shown in FIG. 9, compared to the case where the acceleration / deceleration pattern of FIG. 5 is used. If the difference in the stopping position during normal driving and power-saving driving can be reduced, the aperture diameter can be corrected even if a common correction table 51 is used, and it becomes possible to improve the accuracy of the aperture diameter with a small amount of data.

[0027] In this embodiment, the deceleration speed of the stepping motor 411 during normal driving and during power saving driving in region 2 is the same, but the present invention is not limited to this. If the variation in stopping accuracy during normal driving and during power saving driving is within an allowable range (second predetermined value), the deceleration speed of the stepping motor 411 during power saving driving may have a predetermined width, for example, within 10% of the absolute value of the deceleration speed during normal driving. In other words, if the variation in stopping accuracy during normal driving and during power saving driving is within an allowable range (first predetermined value), the deceleration speed of the diaphragm blades 42 during power saving driving may have a predetermined width, for example, within 10% of the absolute value of the deceleration speed during normal driving. EXAMPLES

[0028] In the first embodiment, the acceleration / deceleration patterns during normal driving and power saving driving are described, but in the present embodiment, the acceleration / deceleration patterns during normal driving and high-speed driving in which the maximum speed of the driving unit is faster than that during normal driving are described. Note that the imaging device of the present embodiment has the same configuration as the imaging device of the first embodiment.

[0029] 10 is a diagram showing an acceleration / deceleration pattern during normal driving (first control pattern) and an acceleration / deceleration pattern during high-speed driving (second control pattern). In FIG. 10, the horizontal axis represents Step, and the vertical axis represents the rotation speed of stepping motor 411.

[0030] In high-speed drive, there is a margin of power, and the aperture 4 is moved at a high speed to improve continuous shooting performance. In high-speed drive, there is a margin of power compared to normal drive, so it is possible to increase the voltage, and the speed can be increased within a range where a margin of torque can be secured. If the speed at which the aperture blades 42 stop differs between normal drive and high-speed drive, the stopping position will vary.

[0031] Therefore, in this embodiment, the speed during deceleration is divided into region 1 and region 2 as shown in Fig. 10. Region 1 is a region in which the deceleration speed is increased while a minimum torque margin is ensured, and region 2 is a region in which a torque margin is ensured at the same deceleration speed as during normal driving. In other words, the deceleration speed during high-speed driving is decelerated to the maximum speed that ensures a torque margin in region 1, and is the same deceleration speed as during normal driving in region 2. This makes it possible to achieve the same stopping position as in normal driving in a short driving time without stepping out.

[0032] Ideally, it is preferable for the switching between area 1 and area 2 during high-speed driving to occur near the middle of the deceleration step during normal driving. This can reduce the variation in the stopping position during normal driving and high-speed driving. On the other hand, area 2 may be made smaller to shorten the driving time. Even in this case, the variation in the stopping position during normal driving and high-speed driving can be reduced by aligning the last step with that during normal driving.

[0033] By using the acceleration / deceleration pattern in Figure 10, it is possible to reduce the variation in the stopping position during normal driving and high-speed driving, making it possible to use a common correction table for correction and improve the accuracy of the aperture system with a small amount of data.

[0034] In this embodiment, the deceleration speed during normal driving and during high-speed driving are the same in region 2, but the present invention is not limited to this. If the variation in stopping accuracy during normal driving and during high-speed driving is within an acceptable range, the deceleration speed during high-speed driving may have a predetermined width, for example, within 10% of the absolute value of the deceleration speed during normal driving. In other words, if the variation in stopping accuracy during normal driving and during high-speed driving is within an acceptable range (first predetermined value), the deceleration speed of the diaphragm blade 42 during high-speed driving may have a predetermined width, for example, within 10% of the absolute value of the deceleration speed during normal driving.

[0035] The disclosure of this embodiment includes the following configuration. (Configuration 1) An aperture blade member; a drive ring that engages with the diaphragm blade member and rotates to form an aperture diameter; A drive unit that drives the drive ring; a control unit that controls the drive unit according to one of a first control pattern and a second control pattern; an absolute value of a difference between a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled in accordance with the first control pattern and a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled in accordance with the second control pattern is smaller than a first predetermined value. (Configuration 2) The aperture drive device described in configuration 1, characterized in that the first predetermined value is 10% of an absolute value of a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled according to the first control pattern. (Configuration 3) 3. The diaphragm drive device according to configuration 1 or 2, characterized in that an absolute value of a difference between a deceleration speed at each position until the drive unit is stopped when the drive unit is driven and controlled according to the first control pattern and a deceleration speed at each position until the drive unit is stopped when the drive unit is driven and controlled according to the second control pattern is smaller than a second predetermined value. (Configuration 4) The aperture drive device described in configuration 3, wherein the second predetermined value is 10% of an absolute value of a deceleration speed at each position leading to a stop of the drive unit when the drive unit is controlled according to the first control pattern. (Configuration 5) The drive unit starts to decelerate in a first region and decelerates until it stops in a second region; The diaphragm drive device according to configuration 3 or 4, characterized in that an absolute value of a difference between a deceleration speed at each position in the second region of the drive unit when driven and controlled in accordance with the first control pattern and a deceleration speed at each position in the second region of the drive unit when driven and controlled in accordance with the second control pattern is smaller than a second predetermined value. (Configuration 6) The aperture drive device described in configuration 5, characterized in that the deceleration speed of the drive unit at each position of the first region and the second region when the drive unit is driven and controlled in accordance with the first control pattern and the second control pattern is set to a deceleration speed that can ensure a torque generated by the drive unit relative to a torque generated by the aperture blade member and the drive ring. (Configuration 7) The aperture drive device described in any one of configurations 1 to 6, characterized in that when the drive unit is driven and controlled in accordance with the first control pattern, the accuracy of the aperture opening diameter is guaranteed to be within an acceptable range. (Configuration 8) 8. The aperture driving device according to any one of configurations 1 to 7, wherein the second control pattern is a pattern in which power is limited as compared to the first control pattern. (Configuration 9) 8. The aperture drive device according to any one of configurations 1 to 7, wherein the second control pattern is a pattern in which the maximum speed of the drive unit is faster than that of the first control pattern. (Configuration 10) 10. The aperture driving device according to any one of configurations 1 to 9, further comprising a storage unit that stores the first control pattern and the second control pattern. (Configuration 11) An aperture drive device according to any one of configurations 1 to 10; and an imaging optical system.

[0036] 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 changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0037] 411 Stepping motor (drive unit) 42 Aperture blades 42A Aperture diameter 44 Drive Ring 6 Lens control unit (control unit)

Claims

1. An aperture blade member; a drive ring that engages with the diaphragm blade member and rotates to form an aperture diameter; A drive unit that drives the drive ring; a control unit that controls the drive unit in accordance with one of a first control pattern and a second control pattern; an absolute value of a difference between a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled in accordance with the first control pattern and a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled in accordance with the second control pattern is smaller than a first predetermined value.

2. 2. The aperture drive device according to claim 1, wherein the first predetermined value is 10% of an absolute value of a deceleration speed at each position until the aperture blade member stops when the drive unit is driven and controlled in accordance with the first control pattern.

3. 3. The diaphragm drive device according to claim 1, wherein an absolute value of a difference between a deceleration speed at each position until the drive unit is stopped when the drive unit is driven and controlled according to the first control pattern and a deceleration speed at each position until the drive unit is stopped when the drive unit is driven and controlled according to the second control pattern is smaller than a second predetermined value.

4. 4. The aperture drive device according to claim 3, wherein the second predetermined value is 10% of an absolute value of a deceleration speed at each position until the drive unit stops when the drive unit is controlled in accordance with the first control pattern.

5. The drive unit starts to decelerate in a first region and decelerates until it stops in a second region; 4. The aperture drive device according to claim 3, wherein an absolute value of a difference between a deceleration speed at each position in the second region of the drive unit when driven and controlled in accordance with the first control pattern and a deceleration speed at each position in the second region of the drive unit when driven and controlled in accordance with the second control pattern is smaller than a second predetermined value.

6. 6. The aperture drive device according to claim 5, wherein a deceleration speed of the drive unit at each position in the first region and the second region when the drive unit is driven and controlled in accordance with the first control pattern and the second control pattern is set to a deceleration speed that can ensure a torque generated by the drive unit relative to a torque generated by the aperture blade member and the drive ring.

7. 3. The diaphragm driving device according to claim 1, wherein when the driving unit is driven and controlled in accordance with the first control pattern, accuracy of the diaphragm opening diameter is guaranteed to be within an allowable range.

8. 3. The aperture drive device according to claim 1, wherein the second control pattern is a pattern in which power is restricted as compared with the first control pattern.

9. 3. The aperture drive device according to claim 1, wherein the second control pattern is a pattern in which the maximum speed of the drive unit is faster than that of the first control pattern.

10. 3. The aperture driving device according to claim 1, further comprising a storage unit that stores the first control pattern and the second control pattern.

11. The aperture drive device according to claim 1 or 2, and an imaging optical system.

Images