Imaging device, its control method and program

Abstract

To provide an imaging device that achieves both reduced drive noise and reduced speed fluctuations. [Solution] An imaging device 100 comprising an imaging unit 1 and drive units 14 and 15 for rotating the imaging unit 1, wherein a control means 16 controls the drive units 14 and 15 to apply a first current value when the rotation speed is less than or equal to a threshold X, and to apply a second current value smaller than the first current value when the rotation speed exceeds the threshold X. The threshold X is a rotation speed preset according to the presence or absence of speed unevenness.

Description

Technical Field

[0001] The present disclosure relates to an imaging device, a control method thereof, and a program.

Background Art

[0002] For example, in an imaging device capable of turning in the pan direction or the tilt direction, high-quality driving, that is, reducing driving noise and reducing speed unevenness, is required. Patent Document 1 discloses a stepping motor control device in an optical device, which controls the current supplied to the stepping motor based on the rotation state (constant speed, acceleration / deceleration, stop) of the stepping motor. Thereby, generation of a large operating noise due to torque excess or the like is prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Speed unevenness is that the speed periodically changes slightly when turning in the pan direction or the tilt direction, and smooth turning drive is required for video quality. To reduce speed unevenness, it is desirable to increase the current value applied to the motor of the drive source, that is, the torque, to improve the holding force of the motor. In Patent Document 1, torque is reduced to reduce driving noise, but no improvement is made to reduce speed unevenness.

Means for Solving the Problems

[0005] The imaging device of the present disclosure comprises an imaging unit and a drive unit for rotating the imaging unit, and includes control means for applying a first current value to the drive unit when the rotation speed is below a threshold, and applying a second current value smaller than the first current value to the drive unit when the rotation speed exceeds the threshold, wherein the threshold is a rotation speed preset according to the presence or absence of speed unevenness. [Effects of the Invention]

[0006] This disclosure makes it possible to provide an imaging device that achieves both reduced drive noise and reduced speed unevenness. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view of the imaging device according to the first embodiment. [Figure 2] This is a block diagram showing an example configuration of an imaging device according to the first embodiment. [Figure 3] This graph shows an example of the relationship between turning speed and drive current value. [Figure 4] This graph shows an example of the relationship between turning speed and drive current value. [Figure 5] This flowchart shows an example of the control process of the imaging device according to the first embodiment. [Figure 6] This flowchart shows an example of the control process of an imaging device according to the second embodiment. [Figure 7] This figure shows an example of a table illustrating the relationship between the shooting angle of view and the threshold. [Figure 8] This flowchart shows an example of the control process of an imaging device according to the third embodiment. [Figure 9] This figure shows a table illustrating the relationship between rotation speed, shooting angle of view, and drive current value, as well as an example of a table illustrating the relationship between rotation speed and drive current value. [Figure 10] This graph shows an example of the relationship between turning speed and drive current value. [Figure 11] This graph shows an example of speed control for the drive unit. [Figure 12]It is a graph showing the state of control switching and drive current value switching. [Figure 13] It is a flowchart showing a control processing example of an imaging device according to a fourth embodiment. [Figure 14] It is a diagram showing the current waveform of a two-phase stepping motor. [Figure 15] It is a diagram showing the current waveform when the drive current value is switched. [Figure 16] It is a diagram showing the current waveform of constant voltage control and the current waveform of constant current control. [Figure 17] It is a diagram showing the state of jerk when control is switched. [Figure 18] It is a diagram showing the state of jerk when the drive current value is switched. [Figure 19] It is a graph showing the state of control switching and drive current value switching. [Figure 20] It is a graph showing the state of control switching and drive current value switching. [Figure 21] It is a diagram showing the current waveform when the switching between microstep drive and full-step drive is performed at 315 degrees. [Figure 22] It is a diagram showing the current waveform when the switching between microstep drive and full-step drive is performed at 90 degrees. [Figure 23] It is a graph showing the state of control switching and drive current value switching. [Figure 24] It is a block diagram showing a configuration example for realizing control switching and drive current value switching. [Figure 25] It is a block diagram showing a configuration example for realizing vector control with a position sensor. [Figure 26] It is a block diagram showing a configuration example for realizing vector control without a position sensor. [Figure 27] It is a block diagram showing a configuration example for realizing control switching and drive current value switching. [Figure 28] It is a diagram showing a hardware configuration example of a control unit (CPU). [Modes for carrying out the invention]

[0008] Preferred embodiments of this disclosure will be described below with reference to the attached drawings. (First Embodiment) The first embodiment will be described with reference to Figures 1 to 5. Figure 1 is a perspective view of the imaging device 100 according to the first embodiment. The imaging device 100 comprises a camera unit 1, a support unit 2, and a base unit 3. The camera unit 1 includes a lens (not shown) and an imaging unit 11 (described later), and the lens is equipped with a zoom function. The camera unit 1 corresponds to the imaging unit as referred to in this disclosure. The support unit 2 supports the camera unit 1 and rotates the camera unit 1 in the tilt direction around the tilt axis L1. The base unit 3 supports the support unit 2 and rotates the camera unit 1 and the support unit 2 in the pan direction around the pan axis L2. This allows the shooting direction of the camera unit 1 to be changed. Rotating in the tilt direction and rotating in the pan direction are also called tilt operation and pan operation, respectively. Such an imaging device 100 is applicable to cameras that perform pan and tilt operations, such as remote cameras, surveillance cameras, and interchangeable lens pan-tilt cameras used in live music venues and photography studios.

[0009] Figure 2 is a block diagram showing an example configuration of the imaging device 100 according to the first embodiment. The imaging device 100 includes an imaging unit 11, a zoom drive unit 12, a shooting angle detection unit 13, a pan drive unit 14, a tilt drive unit 15, a CPU 16, and a storage unit 17. The imaging unit 11 includes an image sensor, such as a CCD or CMOS element, and an A / D converter. An optical image is formed on the image sensor via a lens (not shown) within the camera unit 1. The image sensor outputs an electrical signal (analog signal) corresponding to the optical image, and the A / D converter converts this analog signal into a digital signal and outputs it as image data. The configuration of the image sensor and A / D converter constituting the imaging unit 11 is not limited, and various conventionally known configurations can be applied. In other words, the imaging unit 11 only needs to be configured to generate and output an electrical signal (image data) from the optical image of the subject.

[0010] The zoom drive unit 12 includes a mechanical drive system for zooming, a motor as a drive source, and a motor driver, and is controlled by the CPU 16. The zoom drive unit 12 changes the shooting angle of view by moving a lens (not shown) inside the camera unit 1.

[0011] The shooting angle detection unit 13 detects the shooting angle from the lens movement information of the zoom drive unit 12.

[0012] The pan drive unit 14 is controlled by the CPU 16 and includes a mechanical drive system for panning, a motor as a drive source, and a motor driver. The CPU 16 sets the rotation speed, drive current value, etc., to the pan drive unit 14, and the pan drive unit 14 rotates the camera unit 1 and the support unit 2 in the panning direction. The motor of the pan drive unit 14 is a stepping motor whose rotation speed can be controlled by, for example, a pulse signal.

[0013] The tilt drive unit 15 is controlled by the CPU 16 and includes a mechanical drive system for tilting, a motor as a drive source, and a motor driver. The CPU 16 sets the rotation speed, drive current value, etc., to the tilt drive unit 15, and the tilt drive unit 15 rotates the camera unit 1 in the tilt direction. The motor of the tilt drive unit 15 is a stepping motor whose rotation speed can be controlled by a pulse signal, for example.

[0014] The CPU 16 is responsible for controlling the entire imaging device 100. By executing the program stored in the memory unit 17, the CPU 16 functions as a control means as defined in this disclosure and performs the processing described later.

[0015] The memory unit 17 is an electrically erasable and recordable memory, system memory, work memory, and image memory, and includes, for example, RAM and ROM. The memory unit 17 stores constants and programs for the operation of the CPU 16. The programs stored in the memory unit 17 include a program for executing the flowchart described later. In this embodiment, the memory unit 17 also stores the rotation speed threshold X, which will be described later. The memory unit 17 also stores information detected by the shooting angle detection unit 13.

[0016] Next, referring to Figures 3 and 4, we will explain the control that changes the current value applied to the drive unit for rotation (hereinafter referred to as the drive current value) according to the instructed rotation speed. The drive unit referred to here corresponds to the pan drive unit 14 and tilt drive unit 15 described above, but in the following explanation, we will not distinguish between them and will simply refer to them as the drive unit.

[0017] Figure 3 is a graph showing an example of the relationship between rotation speed (horizontal axis) and drive current value (vertical axis). As shown in Figure 3, in the imaging device 100, the CPU 16 controls the drive current value according to the instructed rotation speed. Two control regions are set for the rotation speed: a speed unevenness control region on the low-speed side of the rotation speed, and a drive noise control region on the high-speed side of the rotation speed. Each control region is described below.

[0018] <Speed ​​unevenness control area> Speed ​​unevenness refers to the periodic small changes in speed when the imaging device 100 is panned or tilted. The effect of speed unevenness is particularly significant when panning or tilting is performed at low speeds, and it becomes noticeable within the shooting angle (the speed unevenness can be visually observed). To reduce speed fluctuations, it is desirable to increase the drive current value, that is, increase the torque, in order to improve the holding force of the motor. However, as the torque increases, the drive noise also increases. However, at the lower end of the turning speed range, the noise from the motor is relatively low. Therefore, at lower turning speeds, motor noise is low and speed fluctuations are noticeable, so reducing speed fluctuations is prioritized. Conversely, at higher turning speeds, motor noise is high and speed fluctuations are not noticeable, so reducing drive noise is prioritized. Specifically, the imaging device 100 sets separate control regions for the purpose of reducing speed unevenness and reducing drive noise, and sets the drive current value I1 of the speed unevenness control region to be greater than the drive current value I2 of the drive noise control region (I2 <I1)。

[0019] <Drive noise control area> As described above, the drive noise control region is a control region that prioritizes reducing drive noise. Since reducing the drive current value (torque) is desirable for reducing drive noise, the drive current value I2 in the drive noise control region is set to be smaller than the drive current value I1 in the speed unevenness control region (I2 <I1)。

[0020] <Threshold X> In this embodiment, a threshold X is set at the boundary between the speed unevenness control region and the drive noise control region. The threshold X is the turning speed at which the drive current value is changed. Specifically, the CPU 16 applies a drive current value I1 to the drive unit to drive it if the turning speed instructed by the user is less than or equal to the threshold X, and applies a current value I2 to the drive unit to drive it if the turning speed instructed by the user exceeds the threshold X. The threshold X is pre-set according to the presence or absence of speed unevenness. The presence or absence of speed unevenness can be determined by the variation in turning speed relative to a certain target speed. Experiments have shown that speed unevenness can be visually observed when the variation in turning speed relative to the target speed is, for example, 0.2 or more. Therefore, the determination of speed unevenness being present (noticeable speed unevenness) can be set to 0.2 or more, and the determination of no speed unevenness (not noticeable speed unevenness) can be set to less than 0.2. In other words, the threshold X is set to the turning speed at which the variation in speed relative to the target speed is less than 0.2.

[0021] Furthermore, the degree to which speed unevenness is noticeable changes depending on whether the shooting angle of view is telephoto or wide-angle. With telephoto, the shooting angle of view is narrower, and the amount of speed change per pixel is larger, so even minute changes in speed become more noticeable. Therefore, the minimum turning speed at which speed unevenness becomes unnoticeable when the shooting angle of view is at its minimum (for example, at the telephoto end) becomes the maximum value of threshold X. In this embodiment, in order to reduce speed unevenness at all shooting angles, threshold X is set to, for example, the minimum turning speed at which speed unevenness becomes unnoticeable at the telephoto end.

[0022] Furthermore, since the threshold X differs between the horizontal and vertical fields of view, the threshold X can be set independently for both panning and tilting operations. A threshold X is set for both the pan drive unit 14 and the tilt drive unit 15, and the CPU 16 controls the pan drive unit 14 and the tilt drive unit 15 independently.

[0023] Figure 4 is a graph showing another example of the relationship between turning speed (horizontal axis) and drive current value (vertical axis). In Figure 3, the graph shows that the drive current value is switched immediately (stepwise) at threshold X, but it is not limited to this. As shown in Figure 4, in the range where the instructed turning speed exceeds threshold X1 and reaches a predetermined turning speed X2 that is greater than threshold X1, the drive current value may be gradually decreased from drive current value I1 to drive current value I2. Note that threshold X1 may be the same value as threshold X in Figure 3. Alternatively, the relationship may be such that threshold X in Figure 3 is located midway between threshold X1 and the predetermined turning speed X2. In short, the drive current value should be set to I1 when speed unevenness is noticeable, and to I2 when speed unevenness is not noticeable, and the method of changing the drive current value is not limited to Figures 3 and 4.

[0024] Next, with reference to Figure 5, control for changing the drive current value according to the instructed rotation speed will be described. Figure 5 is a flowchart showing an example of control processing for the imaging device 100 according to the first embodiment. The processing in the flowchart of Figure 5 is realized by the CPU 16 executing a program stored in the memory unit 17. This flowchart starts when the user puts the imaging device 100 into a state where it can perform pan and tilt operations. This flowchart may also be configured to execute separate processes for pan and tilt operations. In Figure 5, an example is shown where the drive current value is controlled based on the relationship between rotation speed and drive current value as shown in Figure 3.

[0025] In step S101, the CPU 16 detects that the user has specified a turning speed. The method by which the user specifies the turning speed includes, for example, operation via a controller or a preset instruction. Since the preset instruction is a well-known technique, details are omitted. In step S102, the CPU 16 controls the drive unit to initiate the rotation. In step S103, the CPU 16 determines whether the turning speed instructed in step S101 exceeds the threshold value X. If the turning speed is less than or equal to the threshold value X (NO in step S103), the process proceeds to step S104. If the turning speed exceeds the threshold value X (YES in step S103), the process proceeds to step S105.

[0026] In step S104, the CPU 16 sets the drive current value to I1 (> I2) in order to prioritize reducing the speed unevenness. The drive current value I1 corresponds to the first current value referred to in the present disclosure. In step S105, the CPU 16 sets the drive current value to I2 (< I1) in order to prioritize reducing the drive sound. The drive current value I2 corresponds to the second current value referred to in the present disclosure. In step S106, the CPU 16 determines whether the user has turned off the power of the imaging device 100 or the imaging device 100 has entered the standby state. If it is not in the power-off or standby state (NO in step S106), the process returns to step S101 and the processes of steps S101 to S106 are repeated. If it is in the power-off or standby state (YES in step S106), this flow ends.

[0027] As described above, the drive current value in the low-speed region of the turning speed is controlled to be larger than the drive current value in the high-speed region of the turning speed. Thereby, in the speed unevenness control region, the speed unevenness can be reduced, and in the drive sound control region, the drive sound can be reduced, and it becomes possible to provide an imaging device that achieves both reduction of the drive sound and reduction of the speed unevenness.

[0028] Note that the threshold value X may be set by performing unevenness verification for each body after assembling the imaging device 100 at a factory or the like. Also, the user may check the speed unevenness on a display monitor (not shown) or the like, and the user may be able to set the desired turning speed as the threshold value X.

[0029] Furthermore, the drive current values ​​I1 and I2 may be pre-set or user-configurable. For example, default values ​​for drive current values ​​I1 and I2 are set, but if the user does not mind speed unevenness in the speed unevenness region, they may be allowed to select a value smaller than the default value for drive current value I1. In this case, lower power consumption becomes possible. Also, if the user does not mind drive noise in the drive noise region, they may be allowed to select a value larger than the default value for drive current value I2. In this case, torque can be increased to strengthen countermeasures against wind, etc.

[0030] (Second embodiment) A second embodiment will be described with reference to Figures 6 and 7. The basic configuration of the imaging device is the same as that of the imaging device 100 according to the first embodiment. In the following description, components similar to those in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted. Differences from the first embodiment will be described in detail. In the first embodiment, the threshold X is set to a constant value regardless of the shooting angle of view, for example, to the minimum turning speed at which speed unevenness becomes less noticeable when using the telephoto end. In contrast, in the second embodiment, the threshold X is changed according to the shooting angle of view.

[0031] Referring to Figure 6, a control method for changing the drive current value according to the instructed rotation speed will be described. Figure 6 is a flowchart showing an example of control processing for the imaging device 100 according to the second embodiment. The processing in the flowchart of Figure 6 is realized by the CPU 16 executing a program stored in the memory unit 17. This flowchart starts when the user puts the imaging device 100 into a state where it can perform pan and tilt operations. Alternatively, this flowchart may be configured to execute separate processes for pan and tilt operations.

[0032] Step S201 is the same process as step S101 in the first embodiment, and its description will be omitted. In step S202, the CPU 16 acquires the shooting angle T detected by the shooting angle detection unit 13.

[0033] In step S203, the CPU 16 sets the threshold X from a table showing the relationship between the shooting angle of view T and the threshold X, based on the shooting angle of view T acquired in step S202. The table is stored in the storage unit 17. Figure 7 shows an example of a table showing the relationship between the shooting angle of view T and the threshold X. Speed ​​unevenness is less noticeable at wider angles, so as the shooting angle of view T increases, the threshold X is reduced to narrow the speed unevenness control area. That is, when the shooting angle of view T is T1 <T2<···<T n If so, the threshold X is X1 > X2 > ... > X n The relationship is as follows. The shooting angle T and threshold X of the table should be set after verification at a factory or other facility and confirmation by the user, similar to the threshold X described in the first embodiment.

[0034] Steps S204 to S208 are the same processes as steps S102 to S106 in the first embodiment, and their explanation will be omitted.

[0035] As described above, similar to the first embodiment, it is possible to reduce speed unevenness in the speed unevenness control region and reduce drive noise in the drive noise control region, making it possible to provide an imaging device that achieves both reduced drive noise and reduced speed unevenness. Furthermore, in the second embodiment, the drive noise control range can be expanded by changing the threshold X according to the shooting angle.

[0036] While we have described an example where a table showing the relationship between the shooting angle of view T and the threshold X is provided, this is not the only option. For example, one could prepare a calculation formula that uses the shooting angle of view T as a variable to calculate the threshold X, and then in step S203, input the shooting angle of view T into the formula to calculate and set the threshold X.

[0037] (Third embodiment) A third embodiment will be described with reference to Figures 8 to 10. The basic configuration of the imaging device is the same as that of the imaging device 100 according to the first embodiment. In the following, components similar to those in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted. Differences from the first embodiment will be described in detail. In the first and second embodiments, control is performed to change the drive current value using a threshold X. In contrast, in the third embodiment, control is performed to change the drive current value based on a preset characteristic that represents the relationship between the rotation speed, the shooting angle of view, and the drive current value.

[0038] Referring to Figure 8, a control method for changing the drive current value according to the instructed rotation speed will be described. Figure 8 is a flowchart showing an example of control processing for the imaging device 100 according to the third embodiment. The processing in the flowchart of Figure 8 is realized by the CPU 16 executing a program stored in the memory unit 17. This flowchart starts when the user puts the imaging device 100 into a state where it can perform pan and tilt operations. Alternatively, this flowchart may be configured to execute separate processes for pan and tilt operations.

[0039] Steps S301 and S302 are the same processes as steps S101 and S102 in the first embodiment, and their description will be omitted. In step S303, the CPU 16 acquires the shooting angle detected by the shooting angle detection unit 13.

[0040] In step S304, the CPU 16 sets a drive current value I from a table showing the relationship between the rotation speed V, the shooting angle T, and the drive current value I, based on the rotation speed instructed in step S301 and the shooting angle acquired in step S303, and drives the motor with this drive current value I. The table is stored in the storage unit 17. Figure 9(a) is a diagram showing an example of a table showing the relationship between the rotation speed V, the shooting angle T, and the drive current value I. There is a relationship in which the drive current value I decreases as the rotation speed V increases, and also a relationship in which the drive current value I decreases as the shooting angle T increases.

[0041] Step S305 is the same process as step S106 in the first embodiment, and its description will be omitted.

[0042] Figure 10 is a graph showing an example of the relationship between rotation speed (horizontal axis) and drive current value (vertical axis). As shown in Figure 10, in the imaging device 100, the CPU 16 controls the drive current value according to the instructed rotation speed. In this embodiment, instead of controlling the drive current value separately for different ranges of rotation speed (speed unevenness control region and drive noise control region) as in the first and second embodiments, it becomes possible to control the drive current value so that it gradually decreases or becomes constant as the rotation speed increases.

[0043] Note that while an example using a table showing the relationship between rotation speed V, shooting angle of view T, and drive current value I was provided, a table showing the relationship between rotation speed V and drive current value I may also be used. Figure 9(b) is a table showing the relationship between rotation speed V and drive current value I. There is a relationship where the drive current value I decreases as the rotation speed V increases (I1≧I2≧···≧I n-1 ≥I n The relationship between the rotation speed V and the drive current value I may be determined by assuming that the shooting angle of view is at the telephoto end where the range of influence of speed unevenness is greatest with respect to the rotation speed. The rotation speed V, shooting angle of view T, and drive current value I in the table should be set after verification at the factory or by user confirmation.

[0044] As described above, the drive current value in the low-speed range of the rotation speed is controlled to be greater than the drive current value in the high-speed range of the rotation speed. This makes it possible to reduce speed unevenness in the speed unevenness control range and reduce drive noise in the drive noise control range, thereby providing an imaging device that achieves both reduced drive noise and reduced speed unevenness.

[0045] While an example has been given of preparing a table showing the relationship between the rotation speed V, the shooting angle of view T, and the drive current value I (or a table showing the relationship between the rotation speed V and the drive current value I), this is not the only option. For example, a calculation formula for determining the drive current value I could be prepared using the rotation speed V and the shooting angle of view T as variables, and in step S304, the rotation speed V and the shooting angle of view T could be input into the calculation formula to calculate and set the drive current value I.

[0046] (Fourth embodiment) A fourth embodiment will be described with reference to Figures 11 to 18. The basic configuration of the imaging device is the same as that of the imaging device 100 according to the first embodiment. In the following, components similar to those in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted. Differences from the first embodiment will be described in detail. In the fourth embodiment, a configuration is described in which the drive current value is changed (switched) according to the turning speed, and the control other than the change of the drive current body is changed (switched) according to the turning speed. In the fourth embodiment, an example is described in which constant current control and constant current control are switched as the control switching.

[0047] Figure 11 is a graph showing an example of speed control of the drive unit, illustrating the turning speed of the drive unit against time t. It shows the turning speed changing in the order of stop, acceleration, constant speed, deceleration, and stop. While Figure 11 shows simple acceleration and deceleration, it is also possible to transition to deceleration or constant speed during acceleration.

[0048] Figure 12 is a graph showing the switching of control and drive current values, illustrating the switching of control and drive current values ​​during acceleration. First, let's explain how to switch the control. Constant voltage control is a feedforward control method in which the drive current is controlled by pulse width modulation (PWM) of a pre-set voltage to maintain a predetermined value. With constant voltage control, there is no need to monitor the drive current, so the current fluctuation range can be reduced by setting a high PWM frequency, thereby suppressing drive noise. Furthermore, since the PWM frequency can be fixed, drive noise can be suppressed by setting the frequency outside the audible range. In contrast, constant current control monitors the drive current value and performs feedback control to ensure the drive current value reaches the desired value. As a result, low-frequency fluctuations in the current are also fed back, making it less advantageous than constant voltage control in terms of speed fluctuations and drive noise. On the other hand, because the drive current is monitored, feedback control works to increase the drive current when it is insufficient. Therefore, constant current control can increase torque when it is insufficient compared to constant voltage control, and can control the vehicle at higher speeds.

[0049] Figure 12 shows the settings for control appropriate to each speed range. The control is switched between constant voltage control at low speeds and constant current control at high speeds. The threshold value at this time is shown as threshold Pa1. When the drive current is increased or decreased at threshold Pa1, a jerk (acceleration) occurs due to the transition in the drive current. Jerks affect speed unevenness and drive noise. Therefore, the effect of jerks is suppressed by not overlapping the control switching and the drive current value switching. Hereafter, the threshold values ​​for control switching will be collectively referred to as Pa. These controls and the switching of controls are performed by the CPU 16. The CPU 16 has the function of a control unit that controls the drive unit.

[0050] Next, we will explain the drive current values ​​for each region shown in Figure 12 (low power control region, speed unevenness control region, drive noise control region, and torque priority control region). The low-power control region is the period when the device is stopped, and the drive current value is set according to the torque required for holding. When the torque required for holding is small, the drive current value can be reduced to reduce wasted power. Therefore, the drive current value I3 is set to be smaller than the drive current value I2. The speed unevenness control region is set to the drive current value I1, similar to the first embodiment. The drive noise control region is set to the drive current value I2, similar to the first embodiment. The torque-priority control region is a speed range where the turning speed is high and torque is required. Therefore, the drive current value is set to an increased drive current value I1. The thresholds for switching these drive current values ​​are shown as threshold Xa1, threshold Xa2, and threshold Xa3. When the current is increased or decreased by thresholds Xa1, Xa2, and Xa3, a jerk occurs due to the current transition. Hereafter, the thresholds for switching drive current values ​​will be collectively referred to as Xa. Threshold Xa is a threshold for switching drive current values, similar to threshold X in Figure 3 and thresholds X1 and X2 in Figure 4.

[0051] The relationship between threshold Pa and threshold Xa is explained below. Both threshold Pa and threshold Xa are speed thresholds. The CPU 16 determines whether the turning speed calculated exceeds the threshold. It is desirable to provide hysteresis to the thresholds to prevent hunting. However, threshold Xa1, which overlaps with the threshold for switching between stop and drive, does not need to be a speed threshold. The drive current value may be switched before turning begins, starting from the drive start command.

[0052] The procedure of this embodiment will be described with reference to Figure 13. Figure 13 is a flowchart showing an example of control processing of the imaging device 100 according to the fourth embodiment, and shows the procedure for switching the drive current value with speed as a threshold and switching the control. The processing in the flowchart of Figure 13 is realized by the CPU 16 executing a program stored in the memory unit 17.

[0053] In step S801, the CPU 16 obtains the status of the drive unit. The status includes the current control settings (constant voltage control, constant current control), target speed, position information of the drive unit's rotation, drive state (stopped, accelerating, constant speed, deceleration), drive current value, drive current frequency setting, etc. If there is a current detection function or a position detection function, this information is also obtained. In step S802, the CPU 16 calculates the turning speed. For example, it can calculate the turning speed from the frequency of the set drive current. If the drive unit has a reduction mechanism (gear), the CPU 16 calculates the drive speed by multiplying it by the reduction ratio of the reduction mechanism.

[0054] In step S803, the CPU 16 determines whether the speed calculated in step S802 exceeds the threshold Pa. If the speed exceeds the threshold, it is determined to be yes, and the system proceeds to step S804 to transition from the current control settings. If the speed does not exceed the threshold, it is determined to be no, and since there is no change from the current control settings, the system proceeds to step S805. In step S804, since the speed exceeds the threshold Pa, the CPU 16 performs a control switch.

[0055] In step S805, the CPU 16 determines whether the speed calculated in step S802 exceeds the threshold Xa. If it exceeds the threshold, the result is yes, and the system proceeds to step S806 to transition from the current drive current value setting. If the speed does not exceed the threshold, the result is no, and since there is no change from the current control setting, the system proceeds to step S807. In step S806, since the speed exceeds the threshold Xa, the CPU 16 switches the drive current value.

[0056] In step S807, the CPU 16 performs PWM control of the drive unit based on the changed settings. Since threshold Pa and threshold Xa are set to different speeds, steps S803 and S805 may be determined simultaneously. However, steps S804 and S806 should not be changed simultaneously during operation.

[0057] The control of the stepping motor will be explained with reference to Figure 14. In this embodiment, a two-phase (A-phase, B-phase) stepping motor is used as the motor for the drive unit. Figure 14 shows the current waveform of a two-phase stepping motor and illustrates how the two-phase stepping motor is driven in microstep mode. Phases A and B have a 90-degree phase difference, and the motor rotates as the excitation of phases A and B transitions. The direction of rotation is determined by whether the phase difference is lagging or leading. By performing microstep control on the stepping motor, it is possible to drive it with vibration suppressed. Figure 14 shows the operation of microstep control. The current waveform of phase A is explained as a sine curve. In step control of a stepping motor (constant voltage control, constant current control), the speed is determined by the frequency of the drive current. Therefore, the CPU 16 can calculate the turning speed of the stepping motor by acquiring the frequency information of the current waveform set in the drive unit. In addition, the torque of the stepping motor can be increased as the drive current value is increased. In the following explanation of the current waveform diagrams, frequency changes will be omitted for clarity. In reality, when the threshold is exceeded, the velocity changes, and therefore the frequency also changes.

[0058] Refer to Figure 15 to explain the jerk caused by switching the drive current value. Figure 15 shows the current waveform when the drive current value is switched. In Figure 15, the current waveform of phase A and the current waveform of phase B are shown to illustrate the switching from drive current value I2 to drive current value I1, respectively. In Figure 15, the increase in drive current beyond the threshold Xa is shown by a solid line. At the threshold Xa, when the drive current value changes, it deviates from the sine wave and the drive current changes discontinuously. This is when a jerk occurs. Ideally, if the drive currents of phase A and phase B transition instantaneously and the current ratio is maintained, a jerk will not occur. However, in reality, the drive current does not transition instantaneously due to the inductor component of the motor, and a jerk occurs. In the following explanation of the current waveforms, unless otherwise specified, only one of phase A or phase B will be explained.

[0059] Referring to Figure 16, the current waveforms for constant voltage control and constant current control will be explained. Figure 16 shows the current waveforms for constant voltage control and constant current control. In both constant voltage control and constant current control, when the speed is sufficiently slow, macroscopically they both draw the same sine wave, and ideally, it is possible to switch the control without jerk. However, when driven at a certain turning speed, a phase shift occurs in the constant voltage control. Also, in this case, the peak of the drive current in constant voltage control decreases as the speed increases. In contrast, with constant current control, phase shifts are less likely to occur compared to constant voltage control because the current is being monitored. Also, the current peak is less likely to be as low as with constant voltage control. However, if the speed is increased further, the waveform will not be able to keep up and will take on a triangular wave shape (not shown). Thus, because the waveform shape differs depending on the control, a jerk occurs when switching between control systems. Therefore, it is desirable to switch at a speed where constant current control is close to a sine wave and distortion is low.

[0060] Referring to Figure 17, the jerk during control switching will be explained. Figure 17 shows the jerk during control switching. Figure 17 shows the jerk when switching from constant voltage control to constant current control, and when switching from constant current control to constant voltage control. As explained in Figure 15, a phase shift occurs due to the control, so a jerk occurs due to the step in the current during switching. In this embodiment, the threshold Pa for control switching shown in Figure 17 and the threshold Xa for drive current value switching shown in Figure 15 are determined based on the speed, and thresholds Pa and Xa are set to different speeds. This prevents the overlap of control switching and drive current value switching, and suppresses the jerk.

[0061] Refer to Figure 18 to further explain the jerk during drive current value switching. Figure 18 shows the jerk during drive current value switching, and illustrates the case where the switching phase is different from that of Figure 15. In an ideal sine wave waveform, the point where the current is 0 is always 0 regardless of the drive current value setting, so no jerk occurs. However, since the phases of phase A and B are 90 degrees apart, there is no point where both phase A and B are 0 and no jerk occurs. Also, since the motor is rotated by the current ratio of phase A and phase B, it is not possible to change the current of each phase individually. Therefore, jerk will always occur when the drive current value is switched. To stabilize the transition state, it is desirable to set the switching phase to a fixed position such as 0 degrees, 45 degrees, or 90 degrees.

[0062] This section explains the prohibited control interval (time) after a control switch and a drive current value switch. After a control switch and a drive current value switch, the control waveform and moment of inertia may become disturbed, and the control may not be stable. Therefore, it is desirable to set a period (time) during which control switching and drive current value switching are not performed until the control stabilizes. If the control state can be detected (position sensor, voltage detection, current detection), it is desirable to determine whether it is stable in real time from the detection results. If the control state cannot be detected, it is desirable to set the prohibited interval time in advance. When setting the prohibited interval time in advance, it should be determined from the motor's inductance component, resistance component, the voltage used, the motor's vibration characteristics, etc. It is also desirable to set the interval while actually observing the waveform. The prohibited interval should be set within a range that does not affect responsiveness, for example, 100ms.

[0063] A supplementary explanation will be given regarding the switching of drive current values. Figure 15 illustrates the switching between two drive current values, I1 and I2. However, as shown in the first embodiment, the drive current values ​​I1 and I2 may be transitioned in a stepwise manner. This makes it possible to suppress jerks during switching.

[0064] A supplementary explanation of constant voltage control and constant current control is provided. In Figure 12, the low-speed side is shown as being controlled by constant voltage and the high-speed side as being controlled by constant current, but this is not the only option. The low-speed side may be controlled by constant current and the high-speed side by constant voltage, and the same application is possible. In this embodiment, the example of acceleration was used for explanation, but the same principles can be applied to deceleration. Furthermore, while the explanation used a monotonous acceleration scenario, the principles are not limited to this and can be applied to other situations as well. Furthermore, although a two-phase stepping motor was described in this embodiment, a multi-phase stepping motor with three or more phases may also be used.

[0065] (Fifth embodiment) A fifth embodiment will be described with reference to Figure 19. In the fifth embodiment, the suppression of drive noise by reducing the drive current will be described. Figure 19 is a graph showing the switching of control and drive current values, illustrating how the drive noise is suppressed by switching the drive current value. In Figure 19, thresholds Xa4 and Xa5 have been added compared to Figure 12. Motor vibration is sensitive to the drive current value, and changing the drive current value causes a shift in the motor's vibration-frequency characteristics (current frequency). If the motor vibration is large, the drive noise of the imaging device 100 will also increase as a result.

[0066] Therefore, as shown in Figure 19, a threshold Xa4 is set to the speed range in which vibration begins to increase relative to the drive current value I2, and the drive current value is switched to I1. By changing the current in this way, the peak of the motor vibration can be shifted, and the drive noise can be suppressed. Furthermore, when exiting the period in which vibration is large at the drive current value I1, it is desirable to reduce the drive current value and switch to the drive current value I2 to suppress the drive noise (not shown). At this time, by setting thresholds Xa4 and Xa5 to different values ​​from the control threshold Pa, overlapping switches can be prevented and jerking can be suppressed.

[0067] (Sixth embodiment) The sixth embodiment will be described with reference to Figures 20 to 22. The sixth embodiment will describe the case in which microstepping and full stepping (switching the number of divisions in step control) are performed. Figure 20 is a graph showing the switching of control modes and drive current values, illustrating the switching between microstepping and full stepping. In Figure 20, a threshold Pa2 for switching between microstepping and full stepping is added compared to Figure 12. Microstepping is a control method that divides one mechanical step of step control into multiple steps by driving with a sinusoidal wave. As a result, microstepping drive results in smoother rotation, and speed unevenness and drive noise are improved compared to full step drive. However, torque is less easily generated compared to full step drive, which drives each mechanical step individually. Therefore, microstepping is sometimes switched to full stepping to increase speed. In this case, by setting the threshold Pa2 to a different value from the drive current value threshold Xa, it is possible to prevent overlapping of switching and suppress jerk.

[0068] Refer to Figures 21 and 22 for a supplementary explanation of microstepping and full stepping. Figure 21 shows the current waveform when switching between microstep and full-step drive at 315 degrees. Figure 21 shows the currents for phase A and phase B. Here, it shows how the switch occurs when the drive current value for full-step drive and the drive current value for microstep drive overlap. At this time, the current waveform changes from a sine wave for microstep to a trapezoid for full-step, and the current ratio changes, causing a jerk during the switch. Although the case of 315 degrees is shown here, the same applies to 45 degrees, 135 degrees, and 225 degrees.

[0069] Figure 22 shows the current waveform when switching between microstep drive and full step drive at a 90-degree angle. In this case, because the drive current for microstep drive and the drive current for full step drive do not match, the drive current in at least one of phases A or B undergoes a large transition, resulting in a larger jerk than in the case of Figure 14. Although this explanation uses the 90-degree case, the same applies to 0 degrees, 180 degrees, and 270 degrees.

[0070] Furthermore, in phases other than those shown in Figures 21 and 22, phases A and B transition simultaneously, resulting in jerk. Furthermore, as the speed increases to a certain extent, the waveform becomes distorted, which can cause jerks regardless of the phase.

[0071] Let's provide some additional explanation regarding the switching between microstepping and full stepping. While we've discussed the binary switching between microstepping and full stepping, the number of microstep divisions can also be transitioned gradually, for example, from 256 divisions to 128 divisions, then to 64 divisions. This helps to suppress jerks during the transition.

[0072] (Seventh Embodiment) Referring to Figure 23, the seventh embodiment will be described. In the seventh embodiment, the switching between step control (constant voltage control, constant current control) and vector control will be described. Figure 23 is a graph showing the switching of control and drive current values, illustrating the switching between step control and vector control. In Figure 23, a threshold Pa3 for switching between step control and vector control has been added compared to Figure 12. Vector control includes vector control with a position sensor, which uses position information fed back from a position sensor such as an encoder for control, and vector control without a position sensor, which predicts position information from the motor voltage and drive current. In both types of vector control, the motor is driven with a drive current corrected by the amount of the deviation in the rotational position, making it possible to drive while adjusting the drive current value as needed. In contrast, in step control, since position deviation is not detected, a drive current value with a safety factor is set to set a drive current value that does not lose steps. Due to this safety factor, vector control can be driven with lower power consumption.

[0073] It is desirable to switch between step control and vector control between constant current control, which allows for motor phase management by current detection, and vector control. This makes it easier to manage the phase and drive current value. However, if the drive current value of constant current control is changed at the same timing as the vector control switch, the convergence time of vector control will increase due to jerk. Since the control is unstable until convergence occurs, vibration may increase speed fluctuations and drive noise. Therefore, the threshold Pa3 for switching between step control and vector control should be set at a different speed from the drive current value switch Xa. This prevents overlapping switches and suppresses jerk. Furthermore, when switching between step control and vector control, it is desirable to stably switch the control by setting the prohibited interval shown in the first embodiment.

[0074] (Eighth embodiment) The eighth embodiment will be described with reference to Figures 24 to 28. In the eighth embodiment, an example configuration for realizing control switching and drive current value switching will be described. Figure 24 is a block diagram showing an example configuration for realizing control switching and drive current value switching. As shown in Figure 24, it comprises a target speed setting unit 401, a switching determination unit 402, a control switching block 500, a drive current value switching block 600, and a PWM control unit 403 for controlling the motor 404.

[0075] The target speed setting unit 401 sets a target speed in response to a command from the user and updates it with each control cycle. The switching determination unit 402 calculates a speed for determining the switching of control and the switching of the drive current value, and makes a switching determination.

[0076] In the control switching block 500, the constant voltage control unit 501 performs constant voltage control, and the constant current control unit 502 performs constant current control. Constant voltage control and constant current control are switched based on the determination of the switching determination unit 402. The microstep control unit 503 performs microstep control. The full step control unit 504 performs full step control. Microstep control and full step control are switched based on the determination of the switching determination unit 402. The PWM control unit 403 drives the motor 404 by performing PWM control based on the speed determined by the switching determination unit 402. The constant voltage control unit 501 and the constant current control unit 502 control the frequency of the drive current according to the target speed, making it possible to calculate the speed from the target speed. The same applies to the microstep control unit 503 and the full step control unit 504.

[0077] In the drive current value switching block 600, the drive current value is set in step control. Switching is performed in the current value setting unit (I1) 601 and the current value setting unit (I2) 602.

[0078] The control switching block 500 and the drive current value switching block 600 are switched at different speeds based on the determination result of the switching determination unit 402.

[0079] Furthermore, when driving using only step control, detecting the actual speed, as in vector control, is not essential and is therefore omitted in Figure 24. However, as shown in Figures 25 and 26, it is also possible to detect the actual speed and use that speed to determine whether to switch the control in the switching determination unit 402. Also, in Figure 24, constant current control uses current feedback to generate the waveform for PWM control, but this is omitted because it is not related to speed.

[0080] Refer to Figure 25 to explain vector control with a position sensor. Figure 25 is a block diagram showing an example configuration for realizing vector control with a position sensor. Content that overlaps with Figure 24 is omitted. The vector control unit (with position sensor) 505 performs vector control with a position sensor. The vector detection unit 406 acquires position information from the encoder 405 attached to the motor 404 and calculates a vector (detected speed and torque). The switching determination unit 402 makes a switching determination based on the speed calculated by the target speed setting unit 401 or the vector detection unit 406. When using vector control, it is possible to stably switch the control by determining the switching based on the speed calculated by the vector detection unit 406, which is the actual speed. However, the switching determination may also be based on the target speed. The mounting position of the position sensor can be anywhere that can detect the rotational position in conjunction with the motor 404. It may be attached to the rotating shaft of the motor 404, or it may be attached to the final stage of the gear, etc.

[0081] Refer to Figure 26 to explain vector control without a position sensor. Figure 26 is a block diagram showing an example configuration for realizing vector control without a position sensor. Content that overlaps with Figures 24 and 25 is omitted. The vector control unit (without a position sensor) 506 performs vector control without a position sensor. The vector detection unit 406 acquires drive waveform information (voltage / current) from the drive waveform detection unit 407 attached to the motor 404 and calculates a vector (detected speed and torque). The turning speed of the motor 404 can be calculated from the back electromotive force, and the torque can be calculated from the drive current. In addition, in vector control, unlike step control, the drive current value is set based on the vector, so there is no drive current value setting as in step control. The switching determination unit 402 makes a switching determination based on the speed calculated by the target speed setting unit 401 or the vector detection unit 406. When using vector control, it is possible to stably switch the control by determining the switching based on the speed calculated by the vector detection unit 406, which is the actual speed. However, the switching determination may also be made based on the target speed.

[0082] Refer to Figure 27 to explain the switching of control, including vector control. Figure 27 is a block diagram showing an example configuration for realizing control switching and drive current value switching when vector control is included. In Figure 27, compared to Figure 24, a vector control unit (with position sensor) 505 and a vector control unit (without position sensor) 506 are added to the control switching block 500. The diagram illustrates the switching of the constant voltage control unit 501, constant current control unit 502, vector control unit (with position sensor) 505 and vector control unit (without position sensor) 506, and the microstep control unit 503 and full step control unit 504, but it can be applied if any one of the control switching and drive current value switching is performed.

[0083] Next, the values ​​used for determination in the switching determination unit 402 will be explained. If there are multiple speed calculation means (target speed setting unit 401, drive waveform detection unit 407, encoder 405, etc.), the determination is made using the value calculated from any one of them. Alternatively, the speed may be calculated by weighting each of the multiple calculation means. However, the speed used for determination must be uniquely determined. In addition, the calculation means and the weighting ratios of each can be changed based on the control switching state and speed, but the speed used in a single determination must be uniquely determined. For example, when switching between step control and vector control, since feedback that matches the actual rotation is applied in vector control, it is desirable to make the switching determination based on the speed calculated by the vector detection unit 406. Also, when switching within the range of step control, since control is performed based on the target speed, it is desirable to make the switching determination based on the speed calculated from the target speed.

[0084] Referring to Figure 28, we will explain the case where the control unit (CPU16) has multiple control devices, and the switching of control and the switching of drive current values ​​are performed by different devices. Figure 28 is a diagram showing an example of the hardware configuration of the control unit (CPU16). User operation 700 is a pan-tilt operation by the user using a remote controller or the like. MCU701 (MCU: Micro Controller Unit) issues a position command to sub-MCU702 based on the user operation 700. Sub-MCU702 is an MCU equipped with a motion controller, and generates a PWM control waveform based on the position command from MCU701 and the current status (speed, position, type of control, etc.). In this case, the switching of control and the switching of drive current values ​​may be controlled by different MCUs. Here, we will explain the case where MCU701 switches the drive current value based on speed information, and sub-MCU702 switches control based on speed information. MCU701 and sub-MCU702 communicate via serial communication. Even if MCU701 and sub-MCU702 make switching decisions based on the same speed information, the control switching may occur simultaneously depending on the timing of communication between MCU701 and sub-MCU702. Therefore, by setting a priority for MCU701 and sub-MCU702, it is possible to prevent overlapping switching. For example, by setting the priority of MCU701 higher than that of sub-MCU702, and only allowing sub-MCU702 to switch control during periods when MCU701 has not permitted the switching of the drive current value, it is possible to prevent overlapping switching. In this way, even when using multiple MCUs, setting priorities can prevent overlapping switching controls and suppress the occurrence of jerk. Regarding priority, if it is necessary to prevent step loss, control or drive current value switching should be prioritized based on torque. On the other hand, if it is necessary to prioritize speed unevenness or drive noise, appropriate control or drive current value switching should be performed for each.

[0085] A supplementary explanation is provided regarding the method for calculating the speed used to determine the threshold. Even if there are multiple calculated speeds, the determination of whether or not the threshold is exceeded is based on a specific speed. This is because if each threshold were determined by a speed calculated using a different method, the thresholds might overlap due to errors dependent on the calculation method, even if different speeds are set as thresholds. However, if the interval between thresholds is sufficiently large compared to the range of speed error, it is acceptable to determine whether the threshold is exceeded using speeds calculated using different methods. The speed calculation method may be changed based on the current status (speed, position, control type, time after control switching, time after drive current value switching, etc.). Furthermore, the speed calculation method may be calculated by weighting values ​​from different calculation methods.

[0086] Let's add a supplementary explanation regarding the case where two different thresholds are exceeded within the control cycle. In this case, it is desirable to set a priority for each threshold and switch them sequentially, rather than switching both thresholds simultaneously. This makes it possible to suppress jerking. Although we have explained this using two cases as an example, the same applies to cases with three or more thresholds.

[0087] Alternatively, the decision of whether or not to switch the drive current value may be made based on the current status. For example, during constant voltage control, feedback control is not active, so switching the drive current value may prevent normal operation. Therefore, the period during constant voltage control may be set as a time when the drive current value is not switched. In this case, the drive current value is switched after switching to constant current control.

[0088] Although the present disclosure has been described above along with embodiments, these embodiments are merely examples of concrete implementations of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by them. In other words, the present disclosure can be implemented in various ways without departing from its technical concept or its main features. For example, the configuration of the imaging device 100 shown in Figures 1 and 2 is just one example and is not limited thereto. (Other embodiments) This disclosure can also be implemented by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions.

[0089] This embodiment includes the following configuration. (Composition 1) An imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The system includes a control means that applies a first current value to the drive unit when the turning speed is below a threshold, and applies a second current value smaller than the first current value to the drive unit when the turning speed exceeds the threshold. The imaging device is characterized in that the threshold is a rotation speed that is set in advance according to the presence or absence of speed unevenness. (Configuration 2) The system includes a zoom drive unit that changes the shooting angle of view by the aforementioned imaging unit, The imaging apparatus according to configuration 1, characterized in that the control means changes the threshold according to the shooting angle. (Composition 3) The imaging apparatus according to configuration 1 or 2, characterized in that the control means gradually reduces the current value applied to the drive unit from the first current value to the second current value in the range from when the rotation speed exceeds the threshold and until it reaches a predetermined rotation speed greater than the threshold. (Composition 4) The drive unit comprises a pan drive unit that moves the orientation of the imaging unit in the pan direction and a tilt drive unit that moves the orientation of the imaging unit in the tilt direction. The threshold is set for each of the pan drive unit and the tilt drive unit. The imaging apparatus according to any one of configurations 1 to 3, 6, and 7, characterized in that the control means independently controls the pan drive unit and the tilt drive unit. (Composition 5) The imaging apparatus according to any one of configurations 1 to 4, 6, and 7, characterized in that the drive unit comprises a stepping motor. (Composition 6) An imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The system includes a control means that controls the application of a current value to the drive unit based on a preset characteristic representing the relationship between the turning speed and the current value applied to the drive unit. The imaging device is characterized in that the current value applied to the drive unit in the low-speed region of the rotation speed is greater than the current value applied to the drive unit in the high-speed region of the rotation speed. (Composition 7) The imaging apparatus according to configuration 6, characterized in that the aforementioned characteristics represent the relationship between the rotation speed, the shooting angle, and the current value applied to the drive unit. (Composition 8) An imaging device comprising an imaging unit and a drive unit for changing the imaging direction of the imaging unit, A current value switching means that changes the current value applied to the drive unit according to a first speed which is the speed at which the imaging direction of the imaging unit is changed, An imaging apparatus characterized by comprising control switching means for changing controls other than the change in current value by a second speed, which is different from the first speed, that changes the shooting direction of the imaging unit. (Composition 9) The imaging apparatus according to configuration 8, characterized in that the control switching means switches between constant voltage control and constant current control. (Composition 10) The imaging apparatus according to configuration 8 or 9, characterized in that the control switching means switches between step control and vector control. (Composition 11) The imaging apparatus according to any one of configurations 8 to 10, characterized in that the control switching means switches the number of divisions of the step control. (Composition 12) The imaging apparatus according to any one of configurations 8 to 11, characterized in that there is a switching prohibition period after switching by the current value switching means and after switching by the control switching means. (Composition 13) Priority is set for the current value switching means and the control switching means. The imaging apparatus according to any one of configurations 8 to 12, characterized in that if the first speed and the second speed are exceeded simultaneously, the switching is performed starting with the higher priority. (Composition 14) The system comprises a first device for switching the current value and a second device for switching the control, Priorities are set for the first device and the second device, An imaging apparatus according to any one of configurations 8 to 13, characterized in that if a higher-priority device has not performed a switchover, a lower-priority device makes a decision on whether to switch over. (Composition 15) An imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, An imaging device characterized by comprising control means for controlling the current value applied to the drive unit in the low-speed range of the rotation speed to be greater than the current value applied to the drive unit in the high-speed range of the rotation speed. [Explanation of Symbols]

[0090] 1: Camera unit, 2: Support unit, 3: Base unit, 11: Imaging unit, 12: Zoom drive unit, 13: Shooting angle detection unit, 14: Pan drive unit, 15: Tilt drive unit, 16: CPU, 17: Memory unit, 100: Imaging device

Claims

1. An imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The system includes a control means that applies a first current value to the drive unit when the turning speed is below a threshold, and applies a second current value smaller than the first current value to the drive unit when the turning speed exceeds the threshold. The imaging device is characterized in that the threshold is a rotation speed that is set in advance according to the presence or absence of speed unevenness.

2. The system includes a zoom drive unit that changes the shooting angle of view by the aforementioned imaging unit, The imaging apparatus according to claim 1, characterized in that the control means changes the threshold according to the shooting angle.

3. The imaging apparatus according to claim 1 or 2, characterized in that the control means gradually reduces the current value applied to the drive unit from the first current value to the second current value in the range from when the rotation speed exceeds the threshold and until it reaches a predetermined rotation speed greater than the threshold.

4. The drive unit comprises a pan drive unit that moves the orientation of the imaging unit in the pan direction and a tilt drive unit that moves the orientation of the imaging unit in the tilt direction. The threshold is set for each of the pan drive unit and the tilt drive unit. The imaging apparatus according to claim 1 or 2, characterized in that the control means independently controls the pan drive unit and the tilt drive unit.

5. The imaging apparatus according to claim 1 or 2, characterized in that the drive unit comprises a stepping motor.

6. An imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The system includes a control means that controls the application of a current value to the drive unit based on a preset characteristic representing the relationship between the turning speed and the current value applied to the drive unit. The imaging device is characterized in that the current value applied to the drive unit in the low-speed range of the rotation speed is greater than the current value applied to the drive unit in the high-speed range of the rotation speed.

7. The imaging apparatus according to claim 6, characterized in that the aforementioned characteristics represent the relationship between the rotation speed, the shooting angle of view, and the current value applied to the drive unit.

8. An imaging device comprising an imaging unit and a drive unit for changing the imaging direction of the imaging unit, A current value switching means that changes the current value applied to the drive unit according to a first speed which is the speed at which the imaging direction of the imaging unit is changed, An imaging apparatus characterized by comprising control switching means for changing controls other than the change in current value by a second speed, which is different from the first speed, that changes the shooting direction of the imaging unit.

9. The imaging apparatus according to claim 8, characterized in that the control switching means switches between constant voltage control and constant current control.

10. The imaging apparatus according to claim 8, characterized in that the control switching means switches between step control and vector control.

11. The imaging apparatus according to claim 8, characterized in that the control switching means switches the number of divisions of the step control.

12. The imaging apparatus according to any one of claims 8 to 11, characterized in that it has a switching prohibition period after switching by the current value switching means and after switching by the control switching means.

13. Priority is set for the current value switching means and the control switching means. The imaging apparatus according to any one of claims 8 to 11, characterized in that if the first speed and the second speed are exceeded simultaneously, the switching is performed starting with the higher priority.

14. The system comprises a first device for switching the current value and a second device for switching the control. Priorities are set for the first device and the second device. The imaging apparatus according to any one of claims 8 to 11, characterized in that if a higher-priority device has not performed a switchover, a lower-priority device makes a decision on whether to switch over.

15. A control method for controlling an imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The system includes a step of controlling the drive unit to apply a first current value when the turning speed is below a threshold, and to apply a second current value smaller than the first current value to the drive unit when the turning speed exceeds the threshold. A control method for an imaging device, characterized in that the threshold is a rotation speed preset according to the presence or absence of speed unevenness.

16. A control method for controlling an imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The process includes a step of controlling the application of a current value to the drive unit based on a preset characteristic representing the relationship between the turning speed and the current value applied to the drive unit, The control method for an imaging device is characterized in that the current value applied to the drive unit in the low-speed region of the rotation speed is greater than the current value applied to the drive unit in the high-speed region of the rotation speed.

17. A control method for controlling an imaging device comprising an imaging unit and a drive unit for changing the imaging direction of the imaging unit, The steps include changing the current value applied to the drive unit according to a first speed, which is the speed at which the imaging direction of the imaging unit is changed, A control method for an imaging device, characterized by comprising the step of changing control other than the change in current value by a second speed, which is a speed that changes the shooting direction of the imaging unit and is different from the first speed.

18. A program for controlling an imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, The computer is instructed to perform a process that controls the drive unit to apply a first current value when the turning speed is below a threshold, and to apply a second current value smaller than the first current value when the turning speed exceeds the threshold. The program is characterized in that the threshold is a turning speed that is set in advance according to the presence or absence of speed unevenness.

19. A program for controlling an imaging device comprising an imaging unit and a drive unit for rotating the imaging unit, Based on a preset characteristic representing the relationship between the turning speed and the current value applied to the drive unit, the computer is instructed to perform a process to control the application of a current value to the drive unit. The program is characterized in that the current value applied to the drive unit in the low-speed range of the turning speed is greater than the current value applied to the drive unit in the high-speed range of the turning speed.

20. A program for controlling an imaging device comprising an imaging unit and a drive unit for changing the imaging direction of the imaging unit, A process to change the current value applied to the drive unit according to a first speed, which is the speed at which the imaging direction of the imaging unit is changed, A program that causes a computer to perform a process to change control other than the change in current value at a second speed, which is different from the first speed, that changes the shooting direction of the imaging unit.

Images