Imaging apparatus, and control method and program therefor

Abstract

To secure holding force against external force while suppressing power consumption and heat generation.SOLUTION: There is provided an imaging apparatus 1 installed on an installation surface, and the imaging apparatus comprises: a drive mechanism which changes the direction of a unit 300 including a lens; and control means 170 which performs control to: hold the unit 300 with first holding force by supplying electric power to the drive mechanism when acceleration detected by an acceleration sensor 171 detecting the acceleration transmitted from the installation surface to the imaging apparatus 1 is less than a predetermined value; and hold the unit 300 with second holding force larger than the first holding force by supplying the electric power to the drive mechanism when the acceleration detected by the acceleration sensor 171 is equal to or larger than the predetermined value.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an imaging device that includes a drive mechanism for changing the orientation of a unit including a lens and is installed on an installation surface, and a control method and program for the imaging device. [Background technology]

[0002] 2. Description of the Related Art In imaging devices such as surveillance cameras that can be monitored remotely, some are known that allow, in addition to operations such as zooming and focusing, panning and tilting to change the orientation of a unit including a lens (hereinafter referred to as a camera unit) in order to freely set the shooting direction. A stepping motor is suitable as a motor for use in the pan drive mechanism or tilt drive mechanism of such an imaging device. A stepping motor can control the rotation angle, so it is possible to control the pan angle and tilt angle. Furthermore, with a stepping motor, even without electricity being applied, the rotation can be restricted by detent torque to hold the camera unit, making it possible to keep the shooting direction constant.

[0003] As a technique for using a stepping motor, Patent Document 1 discloses a configuration for implementing control in which an excitation current is varied depending on differences in the rotation stop position of an eccentric cam in order to generate a desired torque in a stopped stepping motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6872160 Summary of the Invention [Problem to be solved by the invention]

[0005] If the holding force is insufficient for the weight of the camera unit, then external forces such as vibrations and shocks generated when opening and closing a door or shutter near the installation location can cause the camera unit to shift in position, resulting in a shift in the angle of view being captured. As imaging devices have become increasingly high-quality in recent years, some imaging devices are equipped with large camera units, and there is a risk that the camera unit cannot be held firmly by the detent torque alone. When holding the camera unit, it is possible to hold the camera unit with a holding force greater than the detent torque by energizing and exciting the stepping motor. However, increasing the holding force increases the power consumption of the stepping motor.

[0006] The technology of Patent Document 1 detects the rotation angle of an eccentric cam to control the excitation current, and does not aim to optimize the holding force of the camera unit by taking into account the external force applied to the imaging device.

[0007] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to ensure a holding force against an external force while suppressing power consumption. [Means for solving the problem]

[0008] The imaging device of the present invention is an imaging device that is installed on an installation surface, and is characterized in that it is equipped with a drive mechanism that changes the orientation of a unit including a lens, and a control means that, when acceleration detected by an acceleration sensor that detects acceleration transmitted from the installation surface to the imaging device is below a predetermined value, holds the unit with a first holding force by passing current through the drive mechanism, and, when acceleration detected by the acceleration sensor is equal to or greater than the predetermined value, passes current through the drive mechanism to hold the unit with a second holding force greater than the first holding force. Effect of the Invention

[0009] According to the present invention, it is possible to ensure a holding force against an external force while suppressing power consumption and heat generation. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing an imaging device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the structure of the imaging device according to the first embodiment. [Diagram 3] 1 is a characteristic diagram showing an example of the relationship between stopping torque and power consumption of a stepping motor. [Figure 4] 5 is a flowchart showing a power supply control process for holding the camera unit in the first embodiment. [Diagram 5] 11A and 11B are diagrams illustrating an example of retained power information corresponding to a lens type and a zoom. [Figure 6] 10 is a flowchart showing a power supply control process for holding the camera unit in the second embodiment. [Figure 7] 13 is a flowchart showing a power supply control process for holding the camera unit in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [First embodiment] <Configuration of imaging device 1> FIG. 1 is a perspective view showing an imaging device 1 according to a first embodiment. FIG. 2 is a diagram for explaining the structure of the imaging device 1, where (A) is a perspective cross-sectional view cut along a plane including the P axis (pan axis) and optical axis 301 in FIG. 1, and (B) is a perspective cross-sectional view cut along a plane including the P axis and T axis (tilt axis) in FIG. 1. Note that cables and parts that are not directly related to the present invention are not shown, and their description will be omitted. Also, for convenience of explanation, the shapes of parts may be described in a simplified manner.

[0012] As shown in FIG. 1, the imaging device 1 is a surveillance camera that includes a camera unit 300, a panning section 200, and a bottom unit 100. The camera unit 300 can tilt rotate around a T axis that is approximately parallel to the installation surface and approximately perpendicular to the optical axis 301. The pan movable part 200 on which the camera unit 300 is mounted can pan rotate around a P axis that is approximately perpendicular to the installation surface. By panning and tilting, the orientation of the camera unit 300 can be changed to capture a desired direction. The installation surface refers to a surface on which the imaging device 1 is installed, and refers to a wall, ceiling, desk top, etc., and the bottom surface of the bottom unit 100 is fixed or placed stationary on the installation surface. In this embodiment, the camera unit 300 corresponds to a unit including a lens as referred to in the present invention.

[0013] <Configuration of camera unit 300> The configuration of the camera unit 300 will be described with reference to FIG. As shown in FIG. 2, camera unit 300 includes a camera unit case 330, an optical unit 310 that holds a group of lenses, a lens board 311 that controls the group of lenses, a sensor board 321 on which an imaging sensor 320 is mounted, and a camera frame metal plate 340. In a camera unit case 330 formed of resin or the like, an optical unit 310, a lens board 311, and a sensor board 321 are fixed by a camera frame sheet metal 340. An image sensor 320 such as a CMOS sensor is mounted on the sensor board 321. Light from a subject to be imaged is focused on the image sensor 320 via a group of lenses held by the optical unit 310. Image information focused on the image sensor 320 is transmitted as an electrical signal from the sensor board 321 to a pan unit board 260 in the pan movable part 200 via a cable (not shown). The electrical signal transmitted to the pan unit board 260 is then transmitted to a control board 170 in the bottom unit 100 via a cable (not shown).

[0014] A pair of tilt rotation shafts 350 fixed to a camera frame metal plate 340 are provided on both sides of the camera unit 300. The camera unit 300 is supported by the pan movable part 200 via the pair of tilt rotation shafts 350, and can tilt rotate around the pair of tilt rotation shafts 350 as the center of rotation. The camera unit 300 is tilt-driven by a tilt motor 240 fixed to the pan movable part 200. The farther the center of gravity of the camera unit 300 is from the tilt rotation shafts 350, the greater the torque required for tilt drive and the greater the torque required to hold the camera unit 300.

[0015] <Configuration of the pan movable part 200> The configuration of the pan movable section 200 will be described with reference to FIG. As shown in FIG. 2, panning movable section 200 includes a panning unit case 220, a panning base 210, a pair of camera unit support columns 250 facing each other, a tilt motor 240 constituting a tilt drive mechanism, and a panning unit base plate 260. The pan movable part 200 has a pan base 210 fixed to the pan rotation shaft 230 and a pair of camera unit support columns 250 extending upward from the pan base 210 as strength members. A pair of tilt rotation shafts 350 of the camera unit 300 are rotatably supported by the pair of camera unit support columns 250. A pan unit case 220 formed of resin or the like is fixed to the camera unit support columns 250 and the pan base 210 by fitting or screwing. A tilt motor 240 is fixed to one of the camera unit support columns 250, and the tilt rotation shaft 350 is tilt-driven by the tilt motor 240 via a timing belt, a tilt pulley, a tilt gear, or the like. A pan unit board 260 is fixed to the other camera unit support column 250. The pan unit board 260 relays an electric signal from the camera unit 300 and also controls the driving of the tilt motor 240. When the power consumption of the tilt motor 240 increases, heat is generated by the tilt motor 240 and the pan unit board 260. The heat generated by the tilt motor 240 and the pan unit board 260 is transmitted to the camera frame metal plate 340 via the camera unit support column 250 and the tilt rotation shaft 350, respectively, leading to an increase in temperature of the sensor board 321 and the image sensor 320. Therefore, an increase in the power consumption of the tilt motor 240 is not preferable.

[0016] The pan movable part 200 on which the camera unit 300 is mounted can rotate in its entirety in a pan manner with respect to the bottom unit 100, with a pan rotation shaft 230 as the center of rotation. The pan movable part 200 is pan-driven by a pan motor 190 fixed to the bottom unit 100. The pan motor 190 is housed in the space between the pan unit case 220 and the bottom unit 100, and the rotational force of the pan motor 190 is transmitted to the pan rotation shaft 230 via a timing belt, a pan pulley, and the like. The pan rotation shaft 230 is fixed to the pan base 210, and the above configuration makes it possible to pan the pan movable part 200 with respect to the bottom unit 100.

[0017] <Configuration of bottom unit 100> The configuration of the bottom unit 100 will be described with reference to FIG. As shown in FIG. 2, the bottom unit 100 includes a bottom case 110, metal plates such as a rear metal plate 130 and a bottom metal plate 140, electric boards such as a control board 170 and a power supply board 180, and a pan motor 190 that constitutes a pan drive mechanism. The bottom case 110 forms the bottom unit 100 except for the back surface and the bottom surface. The bottom case 110 is preferably made of a material having both strength and heat dissipation performance, such as aluminum die casting. If the heat generation amount and weight are small and the strength and heat dissipation performance are sufficient, the bottom case 110 may be made of resin. The bottom surface of the bottom case 110 is covered with a bottom metal plate 140, and the back surface is covered with a back metal plate 130 to form a housing, and the components and electric boards accommodated therein are protected. The bottom metal plate 140 is fixed to the bottom case 110, and the imaging device 1 can be installed on an installation surface via the bottom metal plate 140 by using a fixing screw (not shown). The power supply board 180 is installed on the bottom metal plate 140, and the control board 170 is installed above the power supply board 180. The back metal plate 130 has a cutout shape that matches the shape of the terminals mounted on the control board 170 and the power supply board 180, and is fixed to the bottom case 110.

[0018] The control board 170 is equipped with an acceleration sensor 171 that detects acceleration caused by the application of an external force. The acceleration sensor 171 may be a gyro sensor or the like as long as it detects acceleration. Since the external force is input through the bottom metal plate 140 fixed or placed stationary on the installation surface, the acceleration caused by the external force transmitted from the installation surface to the imaging device 1 can be accurately measured by firmly fixing the acceleration sensor 171 to the bottom metal plate 140. Therefore, it is preferable to mount the acceleration sensor 171 on the bottom unit 100 rather than mounting the acceleration sensor 171 on the pan movable part 200 or the camera unit 300 in which parts are interposed between the bottom metal plate 140 and the acceleration sensor 171. In this embodiment, the acceleration sensor 171 is mounted on the control board 170, but it is not necessarily required to be the control board 170 as long as it can be firmly fixed to a position where the acceleration from the bottom metal plate 140 is transmitted. The acceleration sensor 171 may be mounted on the power supply board 180 or other rotation angle sensor boards, LED boards, etc. (not shown). In this manner, the acceleration sensor 171 is fixed in a position within the imaging device 1 where it does not move relative to the installation surface even when the pan motor 190 and the tilt motor 240 are operated.

[0019] The control board 170 receives an image signal from the sensor board 321 via the pan unit board 260, and performs image processing, compresses data to be transmitted, and other processes. The control board 170 is a board that consumes a lot of power and generates a lot of heat, and heat dissipation measures are taken on the upper and lower surfaces of the control board 170. The upper and lower surfaces of the control board 170 are connected to the heat dissipation metal plate 150 via the heat conductive member 151. For example, heat generated from a computing element (not shown) mounted on the upper surface of the control board 170 is thermally conducted to the heat dissipation metal plate 150 via the heat conductive member 151, and is further dissipated through the bottom case 110 by connecting the heat dissipation metal plate 150 to the bottom case 110. These heat generating elements have a large temperature rise, so the temperature margin for the guaranteed operating temperature is small. If the heat generated by the pan motor 190 increases, the temperature of the bottom case 110 rises via the pan base 210 and the pan rotation shaft 230, and the temperature of the heat dissipation metal plate 150 also rises, further reducing the temperature margin of the heat generating elements. Therefore, an increase in heat generation from the pan motor 190 is undesirable.

[0020] <Pan motor / tilt motor control> In the imaging device 1, the pan motor 190 and the tilt motor 240 use stepping motors whose rotation angles can be controlled. FIG. 3 shows an example of the relationship between the stopping torque and power consumption of a stepping motor. Power consumption can also be said to be the power (called holding power) required to generate stopping torque in a stepping motor. In a stepping motor, a stopping torque called detent torque is generated even when no power is applied. The detent torque is a torque composed of cogging torque and friction torque caused by the magnetic attraction force between the magnetic pole and the teeth of the iron core. When holding power is applied to the stepping motor, the stepping motor is excited, and a stopping torque larger than the detent torque is obtained, and the stopping torque increases as the applied holding power is increased.

[0021] If the holding force of the stopping torque that holds the camera unit 300 is small, there is a concern that external vibrations or shocks may cause the camera unit 300 to shift in position, resulting in a failure to capture the desired image. Therefore, by increasing the drive current of the stepping motor and increasing the stopping torque, it is possible to make it difficult for the camera unit 300 to shift in position even when subjected to external vibrations or shocks. However, increasing the stopping torque increases the power consumption of the stepping motor and the heat generation, which raises concerns about a rise in temperature of the motor and its surrounding electrical components.

[0022] In this embodiment, the CPU on the control board 170 controls the power supply to the pan motor 190 via the pan unit board 260, and also controls the power supply to the tilt motor 240, thereby ensuring a holding force against an external force while suppressing power consumption and heat generation. The CPU on the control board 170 executes the following power supply control based on the acceleration detected by the acceleration sensor 171 installed in the bottom unit 100. Specifically, when the acceleration detected by the acceleration sensor 171 is below a predetermined value, the control board 170 holds the camera unit 300 with a first holding force by supplying power to the pan motor 190 and the tilt motor 240. When the acceleration detected by the acceleration sensor 171 is equal to or greater than a predetermined value, the control board 170 holds the camera unit 300 with a second holding force greater than the first holding force by supplying power to the pan motor 190 and the tilt motor 240.

[0023] Fig. 4 is a flowchart showing a power supply control process for holding the camera unit 300 in the first embodiment. This power supply control process is realized by, for example, a CPU on the control board 170 executing a predetermined program. The flowchart in Fig. 4 is started at the timing when the initial operation and the like are completed after the power of the imaging device 1 is turned on. In this embodiment, the flowchart in Fig. 4 is executed as a common process for the pan motor 190 and the tilt motor 240, which will be simply referred to as the motor hereinafter. In step S101, the CPU on the control board 170 applies electricity to the motor to hold the camera unit 300 with a first holding force, which is an initial holding force. The first holding force must be at least a holding force that does not cause the camera unit 300 to shift in position due to gravitational acceleration. With a margin, it is desirable for the holding force to be at least about 1.5 G so that the camera unit 300 does not shift in position.

[0024] In step S102, the CPU on the control board 170 judges whether or not to continue shooting. If shooting is to be continued, the process proceeds to step S103. If shooting is not to be continued, the process exits from this flowchart. In step S103, the CPU on the control board 170 waits for a sampling timing and acquires the acceleration detected by the acceleration sensor 171. The sampling frequency may be about 10 kHz to handle a shock waveform of, for example, 10 ms. In step S104, the CPU on the control board 170 determines whether the acceleration acquired in step S103 is equal to or greater than a predetermined value. The predetermined value is suitably set to, for example, about 0.5 G to 1 G. If the acceleration is equal to or greater than the predetermined value, the process proceeds to step S105. If the acceleration is not equal to or greater than the predetermined value, the process returns to step S102. In this manner, while no external force is being applied and the acceleration is small, the loop of steps S102 to S104 is repeated to continue holding the camera unit 300 with the first holding force.

[0025] In step S105, the CPU on the control board 170 starts holding the motor at the second holding force for a predetermined time by energizing the motor. As shown in FIG. 3, the second holding force is a holding force greater than the first holding force, and the holding power at that time (called the second holding power) is greater than the holding power at the first holding force (called the first holding power). The predetermined time may be determined arbitrarily, but a shorter time results in more power savings. For example, if the predetermined time is set to three seconds, in step S105, the CPU on the control board 170 starts counting three seconds. In step S106, the CPU on the control board 170 waits for the sampling timing and obtains the acceleration detected by the acceleration sensor 171. In step S107, the CPU on the control board 170 determines whether the acceleration acquired in step S106 is equal to or greater than a predetermined value. If the acceleration is equal to or greater than the predetermined value, the process returns to step S105. In step S105, in order to start holding the camera unit 300 at the second holding force for a predetermined time, the CPU on the control board 170 restarts a three-second count while holding the camera unit 300 at the second holding force. If the acceleration is not equal to or greater than the predetermined value, the process proceeds to step S108. In this way, while an external force is being applied and the acceleration is increasing, the loop of steps S105 to S107 is repeated to continue holding the camera unit 300 at the second holding force.

[0026] In step S108, the CPU on the control board 170 judges whether a predetermined time (3 seconds in this embodiment) has elapsed based on the count started in step S105. If the predetermined time has elapsed, the process returns to step S101. If the predetermined time has not elapsed, the process returns to step S106. In this way, the CPU on the control board 170 sequentially acquires the acceleration detected by the acceleration sensor 171 at a sampling period and judges whether it is equal to or greater than a predetermined value. Then, if the CPU on the control board 170 judges that the acceleration is equal to or greater than a predetermined value (Yes in step S104, Yes in S107), it starts holding the second holding force for a predetermined time (3 seconds) (step S105), and if it judges that the acceleration has fallen below the predetermined value (No in step S107), it returns to step S101 and changes the second holding force to the first holding force on the condition that the predetermined time has elapsed (Yes in step S108). Since the external force may be applied again after it has been temporarily removed, the second holding force is designed to continue for a predetermined period of time in preparation for this.

[0027] As described above, by temporarily increasing the holding force of the stepping motor when external vibration or impact is applied while keeping the holding force low, it is possible to prevent the camera unit 300 from shifting out of position. Then, when the external vibration or impact disappears, the holding force can be reduced again. In this way, it is possible to ensure holding force against external forces while suppressing power consumption and heat generation.

[0028] [Second embodiment] In the second embodiment, an example will be described in which the first holding force and the second holding force are made variable according to the position of the center of gravity of the camera unit 300. Note that the basic configuration and processing operations of the imaging device 1 are as described in the first embodiment, and the following description will omit a description of the points in common with the first embodiment and will focus on the points of difference. The position of the center of gravity of the camera unit 300 changes when the position of the lens group (not shown) of the optical unit 310 moves back and forth due to a zoom operation, or when an interchangeable lens is attached to the camera unit 300. When the position of the center of gravity changes, the distance of the center of gravity from the center of rotation of the pan rotation or tilt rotation changes, so that even a small external force is likely to cause the position of the camera unit 300 to shift. On the other hand, if the holding force is set to be large in advance so that the position of the camera unit 300 does not shift even when the position of the center of gravity of the camera unit 300 changes, the holding power will be surplus. Therefore, the first holding force and the second holding force are made variable according to the position of the center of gravity of the camera unit 300, and the holding force required to hold the camera unit 300 is secured with less power consumption.

[0029] The imaging device 1 holds the holding power information corresponding to the lens type and zoom of the interchangeable lens. FIG. 5 shows an example of the holding power information corresponding to the lens type and zoom. The holding power required to hold the camera unit 300 is determined according to the lens type shown in the horizontal column and the zoom shown in the vertical row. For example, when the standard lens is used and the zoom is Wide, the holding power required to hold the camera unit 300 at the center of gravity position at that time is 1.0 W. The holding power information is stored in a memory, which is a storage medium on the control board 170, for example, and the CPU refers to this information to determine the holding power. Such holding power information is prepared in advance for each of the first holding power and the second holding power. Note that in this embodiment, an example in which the lens is interchangeable has been described, but when the lens is fixed, holding power information corresponding only to the zoom may be held. In this embodiment, the holding power information corresponds to the first holding power information and the second holding power information in the present invention.

[0030] Fig. 6 is a flowchart showing a power supply control process for holding the camera unit 300 in the second embodiment. This power supply control process is realized by, for example, a CPU on the control board 170 executing a predetermined program. The flowchart in Fig. 6 is started at the timing when the initial operation and the like are completed after the power of the imaging device 1 is turned on. In this embodiment, the flowchart in Fig. 6 is executed as a common process for the pan motor 190 and the tilt motor 240, which will be simply referred to as the motor hereinafter. In step S201, the CPU on the control board 170 acquires information about the interchangeable lens. Methods for acquiring the information about the interchangeable lens include a method of communicating with the lens, a method of using information about the interchangeable lens input by the user, and the like, but any method may be used as long as it is possible to determine the lens type.

[0031] In step S202, the CPU on the control board 170 judges whether or not to continue shooting. If shooting is to be continued, the process proceeds to step S203. If shooting is not to be continued, the process exits from this flowchart. In step S203, the CPU on the control board 170 acquires the zoom value. In this embodiment, information on the position of the zoom from telephoto (Tele) to wide angle (Wide) is acquired. In step S204, the CPU on the control board 170 reads out a first holding power corresponding to the first holding force from the holding power information stored in the memory, based on the interchangeable lens information acquired in step S201 and the zoom value acquired in step S203. In step S205, the CPU on the control board 170 holds the camera unit 300 with the first holding force, which is the initial holding force, by energizing the motor based on the first holding power read out in step S204. In step S206, the CPU on the control board 170 waits for the sampling timing and obtains the acceleration detected by the acceleration sensor 171. In step S207, the CPU on control board 170 determines whether the acceleration acquired in step S206 is equal to or greater than a predetermined value. If the acceleration is equal to or greater than the predetermined value, the process proceeds to step S208. If the acceleration is not equal to or greater than the predetermined value, the process returns to step S202. In this manner, while no external force is being applied and the acceleration is small, the loop of steps S202 to S207 is repeated to continue holding camera unit 300 with the first holding force while changing the first holding force in response to zoom.

[0032] In step S208, the CPU on the control board 170 obtains the zoom value. In step S209, the CPU on the control board 170 reads out a second holding power corresponding to the second holding force from the holding power information stored in the memory, based on the interchangeable lens information acquired in step S201 and the zoom value acquired in step S208. In step S210, the CPU on the control board 170 starts holding the motor at the second holding power for a predetermined time based on the second holding power read in step S208. The predetermined time is three seconds, the same as in the first embodiment, and in step S210, the CPU on the control board 170 starts counting three seconds. In step S211, the CPU on the control board 170 waits for a sampling timing and obtains the acceleration detected by the acceleration sensor 171. In step S212, the CPU on the control board 170 determines whether the acceleration acquired in step S211 is equal to or greater than a predetermined value. If the acceleration is equal to or greater than the predetermined value, the process returns to step S208. In step S208, in order to start holding the camera unit 300 at the second holding force for a predetermined time, the CPU on the control board 170 restarts a three-second count while holding the camera unit 300 at the second holding force. If the acceleration is not equal to or greater than the predetermined value, the process proceeds to step S213. In this way, while an external force is being applied and the acceleration is increasing, the loop of steps S208 to S212 is repeated to continue holding the camera unit 300 at the second holding force while changing the second holding force according to the zoom.

[0033] In step S213, the CPU on the control board 170 judges whether a predetermined time (3 seconds in this embodiment) has elapsed based on the count started in step S208. If the predetermined time has elapsed, the process returns to step S202. If the predetermined time has not elapsed, the process returns to step S211. In this way, the CPU on the control board 170 sequentially acquires the acceleration detected by the acceleration sensor 171 at a sampling period and judges whether it is equal to or greater than a predetermined value. Then, when the control board 170 judges that the acceleration is equal to or greater than a predetermined value (Yes in step S207, Yes in S212), it starts holding the second holding force for a predetermined time (3 seconds) (step S210), and when it judges that the acceleration has fallen below the predetermined value (No in step S212), it returns to step S202 and changes from the second holding force to the first holding force on the condition that the predetermined time has elapsed (Yes in step S213). Since the external force may be applied again after it has stopped being applied, the second holding force is continued for a predetermined time in preparation for this.

[0034] As described above, while keeping the holding force of the stepping motor low, if external vibration or impact is applied, the holding force is temporarily increased, thereby preventing the camera unit 300 from being displaced. Then, when the external vibration or impact disappears, the holding force can be kept low again. Furthermore, in the second embodiment, the first holding force and the second holding force are made variable according to the center of gravity position of the camera unit 300, so that the holding force necessary to hold the camera unit 300 is secured, and surplus holding power can be reduced to save power. In this way, it is possible to secure the holding force against external forces while suppressing power consumption and heat generation. In this embodiment, the first holding force and the second holding force are variable, but for example, the second holding force may be constant regardless of the lens type or zoom. For example, when the second holding force is the maximum stop torque (see FIG. 3) or a value close to the maximum stop torque, the second holding force may be a fixed value.

[0035] [Third embodiment] In the third embodiment, an example will be described in which the pan drive mechanism and the tilt drive mechanism separately execute power supply control for holding the camera unit 300. Note that the basic configuration and processing operations of the imaging device 1 are as described in the first and second embodiments, and the following description will omit description of commonalities with the first and second embodiments and will focus on differences. As shown in FIG. 1, the direction of the P axis is the Z axis direction, and the two directions perpendicular to the Z axis are the Y axis direction and the X axis direction. In the third embodiment, the acceleration sensor 171 detects the acceleration in each of the X axis, Y axis, and Z axis directions, and the pan motor 190 and the tilt motor 240 change the first holding force and the second holding force separately, that is, independently of each other. Since the Z axis direction is parallel to the P axis, the acceleration in the Z axis direction does not affect the pan rotation. Therefore, the pan motor 190 changes the first holding force and the second holding force based on the combination of the acceleration in the X axis and Y axis directions. On the other hand, since the tilt motor 240 rotates around the P axis, the T axis changes the first holding force and the second holding force based on the combination of the acceleration in the X axis, Y axis, and Z axis directions. In this embodiment, similarly to the second embodiment, the first holding force and the second holding force are made variable according to the center of gravity position of the camera unit 300. The imaging device 1 holds held power information for the pan motor 190 corresponding to the lens type and zoom of the interchangeable lens, and held power information for the tilt motor 240 corresponding to the lens type and zoom of the interchangeable lens.

[0036] Fig. 7 is a flowchart showing a power supply control process for holding the camera unit 300 in the third embodiment. This power supply control process is realized by, for example, a CPU on the control board 170 executing a predetermined program. The flowchart in Fig. 7 starts when the imaging device 1 is powered on and the initial operation and the like are completed. In step S301, the CPU on the control board 170 acquires information about the interchangeable lens. In step S302, the CPU on the control board 170 obtains the zoom value. In step S303, the CPU on the control board 170 collectively reads out a first holding power corresponding to the first holding force and a second holding power corresponding to the second holding force from the holding power information stored in the memory for each of the pan motor 190 and the tilt motor 240, based on the interchangeable lens information acquired in step S301 and the zoom value acquired in step S302. In step S304, the CPU on the control board 170 holds the camera unit 300 with a first holding force, which is an initial holding force, by energizing the pan motor 190 and the tilt motor 240 based on the first holding power read out in step S303.

[0037] In step S305, the CPU on the control board 170 waits for a sampling timing and acquires the acceleration in each of the X-axis, Y-axis, and Z-axis directions detected by the acceleration sensor 171. In step S306, the CPU on the control board 170 calculates a composite acceleration in the X-axis, Y-axis, and Z-axis directions using the acceleration acquired in step S305. In step S307, the CPU on the control board 170 determines whether the resultant acceleration calculated in step S306 is equal to or greater than a predetermined value. If the resultant acceleration is equal to or greater than the predetermined value, the process proceeds to step S308. If the resultant acceleration is not equal to or greater than the predetermined value, the process proceeds to step S309. In step S308, the CPU on control board 170 starts holding the second holding force in the tilt direction for a predetermined time by energizing tilt motor 240 based on the second holding power read out in step S303. The predetermined time is three seconds, the same as in the first and second embodiments, and in step S308, the CPU on control board 170 starts counting three seconds.

[0038] In step S309, the CPU on the control board 170 calculates a composite acceleration in the X-axis and Y-axis directions using the acceleration acquired in step S305. In step S310, the CPU on the control board 170 determines whether the resultant acceleration calculated in step S309 is equal to or greater than a predetermined value. If the resultant acceleration is equal to or greater than the predetermined value, the process proceeds to step S311. If the resultant acceleration is not equal to or greater than the predetermined value, the process proceeds to step S312. In step S311, the CPU on the control board 170 starts holding the second holding force in the pan direction for a predetermined time by energizing the pan motor 190 based on the second holding power read out in step S303. The predetermined time is three seconds, the same as in the first and second embodiments, and in step S311, the CPU on the control board 170 starts counting three seconds.

[0039] In step S312, the CPU on the control board 170 determines whether or not the tilt direction is being held with the second holding force. If it is being held with the second holding force, the process proceeds to step S313. If it is not being held with the second holding force, i.e., if it is being held with the first holding force, the process proceeds to step S315. In step S313, the CPU on the control board 170 determines whether a predetermined time (3 seconds in this embodiment) has elapsed based on the counting started in step S308. If the predetermined time has elapsed, the process proceeds to step S314. If the predetermined time has not elapsed, the process proceeds to step S315. In step S314, the CPU on control board 170 changes the holding force in the tilt direction to the first holding force by energizing tilt motor 240 based on the first holding power read out in step S303.

[0040] In step S315, the CPU on the control board 170 determines whether or not the camera is being held with the second holding force in the panning direction. If the camera is being held with the second holding force, the process proceeds to step S316. If the camera is not being held with the second holding force, i.e., if the camera is being held with the first holding force, the process proceeds to step S318. In step S316, the CPU on the control board 170 determines whether a predetermined time (3 seconds in this embodiment) has elapsed based on the count started in step S311. If the predetermined time has elapsed, the process proceeds to step S317. If the predetermined time has not elapsed, the process proceeds to step S318. In step S317, the CPU on the control board 170 changes the holding force in the pan direction to the first holding force by energizing the pan motor 190 based on the first holding power read out in step S303.

[0041] In step S318, the CPU on the control board 170 judges whether or not to continue shooting. If shooting is to be continued, the process proceeds to step S319. If shooting is not to be continued, the process exits from this flowchart. In step S319, the CPU on the control board 170 acquires and updates information about the interchangeable lens. In step S320, the CPU on the control board 170 obtains and updates the zoom value. In step S321, the CPU on the control board 170 reads out, in a batch, a first holding power corresponding to the first holding force and a second holding power corresponding to the second holding force from the holding power information stored in the memory for each of the pan motor 190 and the tilt motor 240, based on the interchangeable lens information acquired in step S319 and the zoom value acquired in step S320. In step S322, the CPU on control board 170 changes the first holding power in the pan direction and tilt direction based on the first holding power read out in step S320, and proceeds to step S305, after which the processes of steps S305 to S322 are repeated.

[0042] As described above, while keeping the holding force of the stepping motor low, when external vibration or impact is applied, the holding force is temporarily increased, thereby preventing the camera unit 300 from being displaced. Then, when the external vibration or impact disappears, the holding force can be kept low again. Also, the first holding force and the second holding force are made variable according to the center of gravity position of the camera unit 300, and the holding force necessary for holding the camera unit 300 is secured, and surplus holding power can be reduced to save power. Furthermore, in the third embodiment, the acceleration in each of the X-axis, Y-axis, and Z-axis directions is detected, and the first holding force and the second holding force are changed independently by the pan motor 190 and the tilt motor 240. As a result, the holding force necessary for holding the camera unit 300 is secured, and surplus holding power can be reduced to save power, compared to generating the same holding force by the pan motor 190 and the tilt motor 240. In this way, it is possible to secure the holding force against external forces while suppressing power consumption and heat generation.

[0043] Although the present invention has been described above with reference to the embodiments, the above embodiments are merely illustrative of the specific examples of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be embodied in various forms without departing from its technical concept or main features. In this embodiment, the CPU on the control board 170 functions as the control means of the present invention, but is not limited to this. For example, a configuration may be adopted in which the CPU on the control board 170 functions as the control means for the tilt motor 240, and the pan unit board 260 functions as the control means for the pan motor 190. Also, an information processing device or the like other than the CPU on the control board 170 may function as the control means of the present invention. (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0044] The disclosure of this embodiment includes the following configuration. [Configuration 1] An imaging device to be installed on an installation surface, A drive mechanism for changing the orientation of a unit including a lens; and a control means for executing control such that, when acceleration detected by an acceleration sensor which detects acceleration transmitted from the installation surface to the imaging device is below a predetermined value, current is passed through the drive mechanism to hold the unit with a first holding force, and when acceleration detected by the acceleration sensor is equal to or greater than the predetermined value, current is passed through the drive mechanism to hold the unit with a second holding force greater than the first holding force. [Configuration 2] 2. The imaging device according to configuration 1, wherein the control means sequentially acquires the acceleration detected by the acceleration sensor and judges whether or not the acceleration is equal to or greater than the predetermined value. [Configuration 3] When the control means determines that the acceleration is equal to or greater than the predetermined value, the control means starts holding the second holding force for a predetermined time, The imaging device described in configuration 2, characterized in that when it is determined that the acceleration falls below the predetermined value, the holding force is changed from the second holding force to the first holding force, provided that the predetermined time has elapsed. [Configuration 4] 4. The imaging device according to any one of configurations 1 to 3, wherein the control means varies the first holding force in accordance with a center of gravity position of the unit. [Configuration 5] information on the first holding force according to the zoom by the lens included in the unit is stored in a storage medium; 5. The imaging device according to configuration 4, wherein the control means determines the first holding force by referring to the information. [Configuration 6] 6. The imaging device according to any one of configurations 1 to 5, wherein the control means varies the second holding force in accordance with a center of gravity position of the unit. [Configuration 7] information on the second holding force according to the zoom by the lens included in the unit is stored in a storage medium; 7. The imaging device according to configuration 6, wherein the control means determines the second holding force by referring to the information. [Configuration 8] The driving mechanism includes a pan driving mechanism and a tilt driving mechanism, 8. The imaging apparatus according to any one of configurations 1 to 7, wherein the control means executes the control separately for the pan drive mechanism and the tilt drive mechanism. [Configuration 9] 9. The imaging device according to configuration 8, wherein the control means executes the control on the pan drive mechanism based on acceleration in two directions perpendicular to the pan axis detected by the acceleration sensor. [Configuration 10] The imaging device described in configuration 8 or 9, wherein the control means executes the control on the tilt drive mechanism based on acceleration in two directions, a direction of the pan axis and an acceleration perpendicular to the pan axis, detected by the acceleration sensor. [Configuration 11] 11. The imaging device according to any one of configurations 1 to 10, wherein the acceleration sensor is fixed at a position within the imaging device such that the acceleration sensor does not move relative to the installation surface even when the drive mechanism is operated. [Explanation of symbols]

[0045] 1: imaging device, 100: bottom unit, 170: control board, 190: pan motor, 200: pan movable part, 240: tilt motor, 300: camera unit, 310: optical unit

Claims

1. An imaging device to be installed on an installation surface, A drive mechanism for changing the orientation of a unit including a lens; and a control means for executing control such that, when acceleration detected by an acceleration sensor which detects acceleration transmitted from the installation surface to the imaging device is below a predetermined value, current is passed through the drive mechanism to hold the unit with a first holding force, and, when acceleration detected by the acceleration sensor is equal to or greater than the predetermined value, current is passed through the drive mechanism to hold the unit with a second holding force greater than the first holding force.

2. 2. The imaging apparatus according to claim 1, wherein the control means sequentially obtains the acceleration detected by the acceleration sensor and judges whether or not the acceleration is equal to or greater than the predetermined value.

3. When the control means determines that the acceleration is equal to or greater than the predetermined value, the control means starts holding the second holding force for a predetermined time, 3. The imaging device according to claim 2, wherein when it is determined that the acceleration falls below the predetermined value, the holding force is changed from the second holding force to the first holding force, provided that the predetermined time has elapsed.

4. 3. The image pickup apparatus according to claim 1, wherein the control means varies the first holding force in accordance with a center of gravity position of the unit.

5. information on the first holding force according to the zoom by the lens included in the unit is stored in a storage medium; 5. The image pickup apparatus according to claim 4, wherein the control means determines the first holding force by referring to the information.

6. 3. The image pickup apparatus according to claim 1, wherein the control means varies the second holding force in accordance with a center of gravity position of the unit.

7. information on the second holding force according to the zoom by the lens included in the unit is stored in a storage medium; 7. The image pickup apparatus according to claim 6, wherein the control means determines the second holding force by referring to the information.

8. The driving mechanism includes a pan driving mechanism and a tilt driving mechanism, 3. The imaging apparatus according to claim 1, wherein the control means controls the pan drive mechanism and the tilt drive mechanism separately.

9. 9. The imaging apparatus according to claim 8, wherein the control means executes the control on the pan drive mechanism based on acceleration in two directions perpendicular to the pan axis detected by the acceleration sensor.

10. 9. The imaging apparatus according to claim 8, wherein the control means executes the control on the tilt drive mechanism based on acceleration detected by the acceleration sensor in two directions, a direction of the pan axis and an acceleration perpendicular to the pan axis.

11. 3. The image pickup apparatus according to claim 1, wherein the acceleration sensor is fixed in a position within the image pickup apparatus such that the acceleration sensor does not move relative to the installation surface even when the drive mechanism is operated.

12. A control method for controlling an imaging device that is provided with a drive mechanism for changing the orientation of a unit including a lens and that is installed on an installation surface, comprising the steps of: A control method for an imaging device, comprising the steps of: when acceleration detected by an acceleration sensor that detects acceleration transmitted from the installation surface to the imaging device is below a predetermined value, current is passed through the drive mechanism to hold the unit with a first holding force; and when acceleration detected by the acceleration sensor is equal to or greater than the predetermined value, current is passed through the drive mechanism to hold the unit with a second holding force greater than the first holding force.

13. A program for controlling an imaging device that includes a drive mechanism for changing the orientation of a unit including a lens and is installed on an installation surface, A program that causes a computer to execute a process to execute control such that, when acceleration detected by an acceleration sensor that detects acceleration transmitted from the installation surface to the imaging device is below a predetermined value, current is passed through the drive mechanism to hold the unit with a first holding force, and when acceleration detected by the acceleration sensor is equal to or greater than the predetermined value, current is passed through the drive mechanism to hold the unit with a second holding force greater than the first holding force.

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