Imaging apparatus

Abstract

To provide a technique that allows appropriate current settings to be executed according to a change of the position of the center of gravity due to a zoom lens of a camera module.SOLUTION: One of imaging apparatuses according to the present invention comprises: a camera module that has a zoom lens mounted therein; a motor that rotates the camera module; a storage unit that stores a current setting table indicating the relationship between a zoom position of the zoom lens and a current value for driving the motor; and a control unit that controls the zoom position of the zoom lens, and sets the current value for driving the motor on the basis of the setting table.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] PZT control is control related to the imaging conditions of a camera, and there are three types of control: panoramic control, tilt control, and zoom control. Some surveillance cameras that support PTZ control are equipped with a motor for rotational movement and a zoom lens with a variable focal length. When a camera equipped with a zoom lens is rotated, the position of the center of gravity of the camera changes depending on the zoom position of the zoom lens. Technological development has been ongoing so that the camera can be rotated efficiently even when such a change in the center of gravity occurs.

[0003] For example, Patent Document 1 aims to "provide a balance weight member that moves back and forth parallel to the photographing optical axis of the television lens device, and move this balance weight member so as to offset the movement of the center of gravity of the television lens device caused by the movement of at least one of the focus lens and the zoom lens, thereby preventing the center of gravity from moving, thereby improving the operability of the television camera by the cameraman," and discloses the following content regarding the television lens device: "Balance weight 40 is arranged so as to be movable back and forth parallel to the photographing optical axis 30 of the television lens device 12. A motor 42 is arranged to move balance weight 40. This motor 42 is driven and controlled by a CPU so that the balance weight 40 moves to a center of gravity offset position. For example, when the focus lens 32 is moved forward and the center of gravity of the television lens device 12 moves forward, the balance weight 40 is moved backward to offset the center of gravity movement." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-149299 Summary of the Invention [Problem to be solved by the invention]

[0005] The farther the camera's center of gravity is from the rotation axis, the more torque is required to rotate the camera. To obtain that torque, it is necessary to increase the current for driving the motor, but if the current is set uniformly, more torque than necessary will be generated, resulting in increased energy consumption. For this reason, Patent Document 1 leaves room for further study on the setting of the motor's drive current. Therefore, an object of the present invention is to provide a technique that enables appropriate current setting in response to a change in the center of gravity position caused by the zoom lens of a camera module. [Means for solving the problem]

[0006] In order to solve the above problems, one representative imaging device according to the present invention is characterized in that it comprises a camera module equipped with a zoom lens, a motor for rotating the camera module, a memory unit for storing a current setting table indicating the relationship between the zoom position of the zoom lens and a current value for driving the motor, and a control unit for controlling the zoom position of the zoom lens and setting the current value for driving the motor based on the setting table. Effect of the Invention

[0007] According to the present invention, an appropriate current setting can be performed in response to a change in the center of gravity position caused by the zoom lens of the camera module. Problems, configurations and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a camera module and a motor. [Diagram 2] FIG. 2 is a diagram showing a schematic diagram of the relationship between the arrangement of the zoom lens and the captured image. [Diagram 3] FIG. 3 is a diagram showing the relationship between the camera module and the position of the center of gravity of the zoom lens. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional block of the imaging apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of the current setting table. [Figure 6] FIG. 6 is a flowchart showing the operation of the imaging apparatus of the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating a schematic configuration of a camera module and a motor. [Figure 8] FIG. 8 is a diagram illustrating an example of a functional block of the imaging apparatus according to the second embodiment. [Figure 9] FIG. 9 is a flowchart showing the process of generating the current setting table. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals.

[0010] In this disclosure, zoom control refers to control for changing the magnification of a zoom lens. Pan control refers to control for rotating a camera module in the horizontal direction, in other words, control for rotating the camera module around an axis extending in the vertical direction. Tilt control refers to control for rotating a camera module in the vertical direction, in other words, control for rotating the camera module around an axis extending in the horizontal direction. In the following description, in order to facilitate understanding, the focus will be on control of the pan direction. Therefore, the configuration for controlling the tilt direction may be omitted in the description, but the present disclosure is also applicable to control of the tilt direction.

[0011] <Example 1> (Change in the center of gravity of the camera module) The change in the center of gravity position of the camera module will be described with reference to FIGS.

[0012] (Camera module configuration) FIG. 1 is a diagram showing a schematic configuration of a camera module and a motor. The camera module 101 is equipped with a zoom lens 102. A motor 104 rotates the camera module 101 via a belt 10 and a rotating shaft 11. Here, the xy plane is a plane parallel to the horizontal direction, and the z-axis direction is the vertical direction. The camera module 101 rotates about a pan reference axis PA when there is control in the pan direction, and rotates about a tilt reference axis TA when there is control in the tilt direction.

[0013] Although motor 104 rotates camera module 101 in the pan direction, it is also possible to rotate camera module 101 in the tilt direction by providing an appropriate gear and a rotation shaft. Alternatively, a separate motor can be provided and controlled to rotate camera module 101 in the tilt direction.

[0014] FIG. 2 is a diagram showing a schematic relationship between the arrangement of a zoom lens and a captured image. The zoom lens 102 includes a plurality of lenses, and enables the zooming in and out of a subject by changing the focal length. The zoom lens 102 includes a focusing lens 21, a lens group 22, and a master lens 23 in a lens barrel 20. Here, the configuration is simplified for ease of understanding. For example, while FIG. 2 shows a configuration including only a convex lens, the zoom lens 102 can also include a concave lens. In addition, the number of lenses included in the lens group 22 is not limited to three, and may include a configuration other than three lenses. The focusing lens 21 can be formed of a lens group including a plurality of lenses, and the master lens 23 can also be formed of a lens group.

[0015] The zoom lens 102 also has a zoom mechanism 24 that changes the arrangement of the focusing lens 21, the lens group 22, and the master lens 23. The zoom mechanism 24 changes the arrangement of these lenses to achieve a zoom position specified by a CPU 103, which will be described later. As the zoom mechanism, for example, a mechanical mechanism can also be adopted.

[0016] The focusing lens 21 is a lens used for focusing. In zoom control, the position of the focusing lens 21 does not change. The lens group 22 may include a variable diameter lens and a correction lens. Furthermore, the focusing lens 21 and the lens group 22 may form an afocal system that does not focus. The master lens 23 constitutes an imaging system, and the focal length of the zoom lens 102 changes based on the magnification of the afocal system of the focusing lens 21 and the lens group 22 and the focal length of the imaging system of the master lens 23 . In this disclosure, zoom control means changing the positions of the lenses included in the lens group 22. Furthermore, the zoom position generally means the arrangement of the lenses included in the zoom lens 102, but in this disclosure, since the focusing lens 21 and the master lens 23 are fixed, it actually means the arrangement of the lens group 22.

[0017] FIG. 2(a) shows the lens arrangement for low magnification, and the diagrams change to FIG. 2(b) and FIG. 2(c), showing lens arrangements for gradually increasing magnification. 2(a) shows a case where the zoom position is set to d1, and the lenses in the lens group 22 are arranged with a large gap between them. The center of gravity 102a of the zoom lens 102 is located near the center of the lens barrel 20 of the zoom lens 102 in the y-axis direction. When capturing an image with the lenses arranged at d1 in FIG. 2(a), the subject 1021 is imaged relatively small near the center of the image 1020.

[0018] 2(b) shows a case where the zoom position is set to d2, and the lenses in the lens group 22 are generally arranged closer to the master lens 23. The center of gravity 102a of the zoom lens 102 is closer to the master lens 23 in the y-axis direction compared to the case of FIG. 2(a). Furthermore, when imaging is performed with the lenses arranged in FIG. 2(b) at d2, the subject 1021 is imaged slightly enlarged in the image 1020.

[0019] 2(c) shows a case where the zoom position is set to d3, and the lenses in the lens group 22 are arranged so close to each other that they almost touch each other. The center of gravity 102a of the zoom lens 102 is located closer to the master lens 23 in the y-axis direction. Compared to FIGS. 2(a) and 2(b), the center of gravity 102a of the zoom lens 102 is located closest to the master lens 23. Furthermore, when imaging is performed with the lenses arranged in FIG. 2(c) at d3, the subject 1021 is imaged so enlarged that it occupies the entire frame of the image 1020.

[0020] Fig. 3 is a diagram showing the relationship between the camera module and the position of the center of gravity of the zoom lens. Fig. 3(a) shows the case where the zoom position is d1, Fig. 3(b) shows the case where the zoom position is d2, and Fig. 3(c) shows the case where the zoom position is d3. As shown in Fig. 3(a), at zoom position d1, the center of gravity 102a is located on the pan reference axis PA. Then, as the zoom position changes from d1 to zoom position d2 in Fig. 3(b) and to zoom position d3 in Fig. 3(c), the center of gravity 102a moves away from the pan reference axis PA in the negative y-axis direction.

[0021] In addition, Fig. 3 also shows the relationship between the position of the tilt reference axis TA and the center of gravity 102a. That is, in Fig. 3(a), the center of gravity 102a is located on the tilt reference axis TA. However, as the zoom position changes from zoom position d2 in Fig. 3(b) to zoom position d3 in Fig. 3(c), the center of gravity 102a also changes in the negative y-axis direction so as to move away from the tilt reference axis TA.

[0022] As described above, the position of the center of gravity 102a of the zoom lens 102 changes significantly depending on the change in the zoom position. Therefore, the torque required for pan control of the camera module 101 also changes depending on the positional relationship between the center of gravity 102a and the pan reference axis PA. If it is possible to appropriately set the drive current of the motor 104 depending on the required torque, it is possible to perform pan control of the camera module while suppressing power consumption.

[0023] 3 shows a case where the tilt reference axis TA and the pan reference axis PA pass across the camera module 101, but the present disclosure is not limited to this. The present disclosure can also be applied to a case where the tilt reference axis TA and the pan reference axis PA are located at positions away from the camera module 101.

[0024] (Configuration of imaging device) Next, the configuration of the imaging apparatus of the first embodiment will be described with reference to FIGS. 4 is a diagram showing an example of functional blocks of the imaging device of the embodiment 1. The imaging device 100 includes a camera module 101 equipped with a zoom lens 102, a motor 104 that rotates the camera module 101, a storage unit 106 that stores a current setting table indicating the relationship between the zoom position of the zoom lens 102 and the current value for driving the motor 104, and a control unit 103 that controls the zoom position of the zoom lens 102 and sets the current value for driving the motor 104 based on the current setting table. A specific description will be given below.

[0025] The camera module 101 is equipped with a zoom lens 102. In addition to the zoom lens 102, the camera module 101 may also be equipped with optical elements, electronic circuits, and the like, and may have a function of controlling these internal devices from outside the camera module 101.

[0026] The CPU 103, which is the control unit, performs PTZ control, controls the zoom mechanism 24 of the zoom lens 102 of the camera module 101 to perform zoom control, and drives the motor 104 to perform pan control and tilt control. When the motor 104 is a stepping motor, the CPU 103 outputs a pulsed drive signal for driving the motor 104. The motor driver 105 converts the drive signal into a current and outputs it to the motor 104. The motor driver 105 has a function of adjusting the current to be output to the motor 104, and the current value is set by the CPU 103.

[0027] The storage unit 106 stores a current setting table that holds current setting values ​​corresponding to zoom positions. The current setting values ​​are current values ​​output by the motor driver 105. The current setting table will be described later.

[0028] The storage unit 106 can also store information other than the current setting table. For example, when the imaging device 100 is used as a surveillance camera, it can also store schedule information that specifies imaging conditions for each time. Furthermore, the CPU 103 can control the imaging device 100 to acquire image information while performing PTZ control according to the schedule. The acquired image information can also be sent to the outside by, for example, the IF unit 107 described later.

[0029] The IF (interface) unit 107 receives information input from outside the imaging device 100. For example, when the imaging device 100 is remotely operated, the IF unit 107 receives an instruction transmitted from outside and transfers the transmitted instruction to the CPU 103. Instructions input from outside include setting a zoom position, designating an imaging direction, etc. Also, a user of the imaging device 100 can input a current setting table to be stored in the storage unit 106 via the IF unit 107.

[0030] 5 is a diagram showing an example of a current setting table. The current setting table 1061 is a table applied when a zoom lens of model H01 is used as the zoom lens 102. When the zoom position is d1, the current setting value for pan control is Ip1, and the current setting value for tilt control is It1. Similarly, when the zoom position is d2, the current setting value for pan control is Ip2, and the current setting value for tilt control is It2. When the zoom position is d3, the current setting value for pan control is Ip3, and the current setting value for tilt control is It3. Note that in the current setting table, the number of zoom positions is not limited to three, and may be other than three.

[0031] The current setting table 1061 can be acquired in advance. For example, the center of gravity position of the camera module 101 is measured for each zoom position, and necessary torques such as an acceleration torque for rotating the camera module 101 and a deceleration torque for stopping the rotation are calculated so that the rotation control is performed within an allowable time. The current setting table 1061 can be acquired by calculating the drive current of the motor 104 for realizing the necessary torque for each zoom position. The CPU 103 performs zoom control and controls the zoom mechanism 24 so that the zoom lens 102 is at a predetermined zoom position. The CPU 103 also performs pan control and tilt control, extracts a current setting value corresponding to the set zoom position from the current setting table 1061, and sets the current setting value in the motor driver 105. In this way, it is possible to supply an appropriate drive current to the motor 104 when driving the motor driver 105.

[0032] Moreover, the current setting table is set for each model of the zoom lens. The current setting table 1061 is applied when the zoom lens 102 is a zoom lens of model H01. On the other hand, the current setting table 1062 is a table applied when the zoom lens 102 is a zoom lens of model H02, which is a different model of the zoom lens. The model of the zoom lens 102 can be determined by the CPU 103, or the user of the imaging device 100 can notify the CPU 103 of the model through the IF unit 107. By setting a current setting table for each model, it is possible to supply a more appropriate driving current to the motor 104. The storage unit 106 can also store two or more current setting tables.

[0033] (Control flow chart) The control of the imaging device 100 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the operation of the imaging device of the first embodiment. In step S601, the CPU 103 detects that zoom control of the camera module 101 has been performed as a trigger. Then, in step S602, the CPU 103 acquires the zoom position of the zoom lens 102 set by the zoom control. Then, in step S603, the CPU 103 acquires a current setting value corresponding to the zoom position of the zoom lens 102 acquired in step S602 by referring to a current setting table. Then, in step S604, the CPU 103 sets the acquired current setting value in the motor driver 105. In this manner, a series of controls is completed (step S605).

[0034] (Actions and Effects of Example 1) As described above, according to the present disclosure, it is possible to set an appropriate current in response to a change in the center of gravity caused by the zoom lens of the camera module. If pan control and tilt control are performed without using a current setting table, a torque more than necessary may be generated depending on the position of the center of gravity 102a of the zoom lens 102, and excess power may be consumed. In addition, if excessive torque is generated, an overload such as sudden acceleration or sudden deceleration may be applied to the motor 104, and a step-out state in which the motor 104 is not synchronized with the control of the CPU 103 may occur. According to the present disclosure, it is possible to set an appropriate current in response to the zoom position, and it is possible to reduce power consumption.

[0035] <Example 2> While the current setting table in the first embodiment is acquired in advance, the current setting table in the second embodiment is created in the imaging device, which is different from the first embodiment. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0036] The configuration of the camera module 101 of the second embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing a schematic configuration of a camera module and a motor. In the second embodiment, a rotary encoder 108 that detects the rotation of the camera module 101 is arranged as a rotation amount detection unit. The rotary encoder 108 detects the rotation angle and the number of rotations of the rotating shaft 11. By detecting the rotation of the rotating shaft 11 by the rotary encoder 108, the CPU 203 can detect the rotation of the motor 104 and the rotation of the camera module 101.

[0037] In order to detect the rotation of the camera module 101 during tilt control, a rotary encoder can be provided for the rotation axis corresponding to the tilt reference axis TA.

[0038] The configuration of an imaging device according to the second embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of functional blocks of the imaging device according to the second embodiment. The imaging device 200 includes a rotary encoder 108. The rotary encoder 108 detects the rotation of the camera module 101 and transmits the detection result to a CPU 203.

[0039] The CPU 203 has a drive amount counting unit 109 that outputs a drive amount count value indicating the drive amount for rotating the motor 104, a rotation amount counting unit 110 that outputs a rotation amount count value indicating the rotation amount of the motor 104 based on the rotation detected by the rotary encoder 108, a step-out determination unit 111 that determines whether step-out has occurred in the motor 104 based on the drive amount count value and the rotation amount count value, and a table generating unit 112 that generates a current setting table based on the determination result of the step-out determination unit 111. For example, the storage unit 106 also has a function as a memory, and has a program that functions as the drive amount counting unit 109, the rotation amount counting unit 110, the step-out determination unit 111, and the table generating unit 112 by the CPU 203 executing a program.

[0040] The generation process of the current setting table will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the generation process of the current setting table. In the generation process, the CPU 203 performs pan control or tilt control while changing the zoom position, and detects the current setting value at the time when the motor 104 loses synchronization.

[0041] First, the process of generating the current setting table is started, for example, before the imaging device 200 is used and when the zoom lens 102 is replaced (step S901).

[0042] Next, in step S902, the CPU 203 detects the model of the zoom lens 102. The CPU 203 acquires information related to the model of the zoom lens 102 via the IF unit 107. It is also possible to configure the CPU 203 to be notified of the model of the zoom lens 102 when the zoom lens 102 is placed in the imaging device 200.

[0043] Next, in step S903, the CPU 203 performs zoom control and sets the zoom position. As shown in steps S903 to S914, the zoom position is repeatedly set from the minimum magnification to the maximum magnification. The zoom position can be changed, for example, by increasing it at a predetermined rate. For example, when the magnification of the zoom lens 102 is controlled in increments of 5 points, such as 10x, 15x, 20x, ..., it is also possible to change the zoom position to correspond to the 5-point increment and repeatedly perform step S903.

[0044] Next, in step S904, the CPU 203 sets a current value to be output to the motor driver 105. As shown in steps S904 to S913, the current value is repeatedly set from a predetermined initial value to the rated current of the motor 104. The predetermined initial value can be set in advance. Also, the current can be increased at a predetermined rate, similar to the change in the zoom position. For example, it is possible to set a value that is 1 / 100 of the rated current of the motor 104 as the increment ΔI of the current value, and add ΔI to the current value each time step S904 is repeated.

[0045] Next, in step S905, a drive amount count value DC is initialized by substituting 0, and a rotation amount count value RC is initialized by substituting 0.

[0046] Next, in step S906, the CPU 203 outputs a pulse signal to drive the motor 104. As shown in steps S906 to S912, the pulse signal is repeatedly output up to a number Nmax corresponding to the case where the camera module 101 is rotated only once in the pan direction, for example.

[0047] Next, in step S907, the drive amount counter 109 increments the drive amount count value DC every time the pattern of the pulse signal changes, and measures the drive amount by which the motor 104 rotates.

[0048] Next, in step S908, the rotation amount counting unit 110 detects the amount of rotation of the rotating shaft 11 detected by the rotary encoder 108, and determines whether the detected amount of rotation is equal to Δθ. Here, Δθ is the amount of rotation corresponding to one count of the drive amount count value DC. If the detected amount of rotation is equal to Δθ (Yes in step S908), then in step S909, the rotation amount counting unit 110 increments the rotation amount count value RC. On the other hand, if the detected amount of rotation is different from Δθ (No in step S908), then the rotation amount counting unit 110 proceeds to step S910 without incrementing the rotation amount count value RC.

[0049] Next, in step S910, the synchronization failure determination unit 111 compares the drive amount count value DC with the rotation amount count value RC. If the drive amount count value DC and the rotation amount count value RC are different (No in step S910), the synchronization failure determination unit 111 determines that the motor 104 has experienced a synchronization failure.

[0050] When the out-of-step determination unit 111 determines that out-of-step has occurred, the table generation unit 112 extracts the zoom position and the current value set in the motor driver 105 (step S911). Then, the table generation unit 112 records the relationship between the zoom position and the current setting value for each model of the zoom lens 102, and generates a current setting table. For example, the current setting value may be the current value at which out-of-step has been determined minus the increment ΔI in the current value in step S904.

[0051] On the other hand, if the drive amount count value DC and the rotation amount count value RC are equal (Yes in step S910), the next pulse signal is set (step S912), and the next current value is set (step S913).

[0052] The above-mentioned step-out determination is performed for all zoom positions (step S914), and the process ends in step S915.

[0053] (Actions and Effects of Example 2) There may be individual differences in zoom lenses and motors for each product. If the current setting table is set uniformly, the effects of individual differences are not taken into account, and so PTZ control may not be performed properly.

[0054] In contrast, in the second embodiment, the current setting table is generated before the imaging device 200 is used and at the time of replacing the zoom lens 102. Since the current setting table is generated for each imaging device, it becomes possible to perform PTZ control under optimal conditions for each imaging device.

[0055] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0056] 10: belt, 11: rotating shaft, 20: lens barrel, 21: focusing lens, 22: lens group, 23: master lens, 24: zoom mechanism, 100: imaging device, 101: camera module, 102: zoom lens, 102a: center of gravity, 103: CPU, 104: motor, 105: motor driver, 106: memory unit, 107: IF unit, 108: rotary encoder, 109: drive amount counting unit, 110: rotation amount counting unit, 111: step-out determination unit, 112: table generation unit, 200: imaging device, 203: CPU, 1020: image, 1021: subject, 1061: current setting table, 1062: current setting table

Claims

1. A camera module equipped with a zoom lens; a motor for rotating the camera module; a storage unit that stores a current setting table that indicates a relationship between a zoom position of the zoom lens and a current value for driving the motor; a control unit that controls a zoom position of the zoom lens and sets a current value for driving the motor based on the current setting table.

2. 2. The image pickup apparatus according to claim 1, wherein the current setting table is set for each model of the zoom lens.

3. A rotation amount detection unit that detects a rotation of the camera module is further provided. The control unit is a drive amount counting unit that outputs a drive amount count value indicating a drive amount for rotating the motor; a rotation amount counting unit that outputs a rotation amount count value indicating the rotation amount of the motor based on the rotation detected by the rotation amount detecting unit; a step-out determination unit that determines whether step-out has occurred in the motor based on the drive amount count value and the rotation amount count value; 3. The imaging device according to claim 1, further comprising: a table generating section that generates the current setting table based on a result of determination by the out-of-step determining section.

Images