JP2004246294A - Camera moving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a small-sized monitor camera device and to obtain a monitor camera device which is free of restrictions of a microcomputer etc. for control and whose vibration is small when rotating even when using an existent standard motor driver. <P>SOLUTION: The camera moving device is characterised by being provided with a stepping motor 9a which moves the direction of a camera, a driving driver 8a which inputs a pulse signal and an electric control signal controlling the value of a current supplied to the stepping motor 9a and drives the stepping motor by using the inputted pulse signal and current control signal, and a turntable control part 7 which generates and outputs the pulse signal and current control signal to the driving driver 8a to control movement of the direction of the camera. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surveillance camera device capable of turning a camera for monitoring by turning a turntable in an arbitrary direction, and more particularly to reduction of rotational vibration during microstep driving of a turntable drive motor.
[0002]
[Prior art]
As a conventional technique, there is the following technique as a technique for changing an excitation position or an excitation balance of a phase, that is, a technique of a micro step itself.
[0003]
As a technique for changing the excitation position, in a conventional mini-step (synonymous with micro-step) driving device of a stepping motor, a predetermined number of additional pulses are generated for each input pulse in order to reduce rotational vibration during micro-step driving. The excitation signal for the input pulse is switched stepwise by the additional pulse (the motor rotation angle is switched stepwise by the additional pulse). (See Patent Document 1)
[0004]
As a technique for approaching the ideal torque, that is, as a technique for changing the phase excitation balance, the following means aimed at providing a driving device for a stepping motor capable of performing a smooth drive with a small torque fluctuation while keeping the step angle unchanged. It is known. A plurality of drivers that have a plurality of magnetically coupled phase coils and sequentially drive the phase coils to excite them, compare a current control reference signal with a signal corresponding to each phase coil current, and send a constant current control signal to each driver. In a stepping motor driving device including a plurality of comparators for outputting and a control circuit for generating a phase switching signal to be applied to each driver, a level of each current control reference signal input to each of the comparators is switched in a plurality of steps. In addition to providing a level switching means formed so as to be able to perform excitation switching from the one-phase coil not magnetically coupled to the other phase coil, the phase coil current of the one-phase coil is reduced stepwise and the phase of the other phase coil is reduced. A predetermined procedure is provided to the level switching means so as to change the current value ratio of the two-phase coil current while increasing the coil current in a stepwise manner. Characterized in that a ratio switching signal generating means for generating a ratio switching signal to the level switching operation. (See Patent Document 2)
[0005]
[Patent Document 1]
JP-A-1-218395 (page 3-7, FIG. 3)
[Patent Document 2]
JP-A-6-98597 [0006]
[Problems to be solved by the invention]
Since the conventional mini-step drive device is configured as described above, it is necessary to provide an additional pulse generation unit in order to reduce the rotational vibration of the monitoring camera device, so that the circuit scale increases and the substrate becomes large. There is a problem that the equipment becomes large and a small device cannot be obtained. In addition, since the excitation signal is switched by the additional pulse, the timing of the additional pulse is increased, and there is also a problem that the pulse timing is restricted by the control microcomputer or the like, and a sufficient effect cannot be obtained. If the microstep resolution itself is further subdivided by additional pulses, and if it is necessary to further reduce the vibration during rotation using an existing standard motor driver with a fixed microstep resolution, There is also a problem that it cannot be adopted.
[0007]
The present invention can provide a small surveillance camera device because there is no need to provide an additional pulse generation unit, and is not restricted by a control microcomputer or the like. An object is to obtain a surveillance camera device with small vibration.
[0008]
[Means for Solving the Problems]
A camera moving device according to the present invention includes a stepping motor that moves the direction of a camera,
A motor driver that inputs a pulse signal and a current control signal for controlling a current value flowing to the stepping motor, and drives the stepping motor using the input pulse signal and the current control signal;
A control unit that generates the pulse signal and the current control signal, and outputs the generated pulse signal and the current control signal to the motor driver to control movement of the camera. And
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a surveillance camera device according to the first embodiment.
In FIG. 1, a surveillance camera device 1 includes a camera unit 2 for capturing a surveillance image and a turntable 3 (an example of a camera moving device) for turning the camera unit 2 in an arbitrary direction. The camera unit 2 includes a camera control unit 5 that inputs a command signal 4 and a sensor / lens unit 6 that captures an image. The turntable unit 3 receives a turntable operation command 10 from the camera control unit 5 and outputs drive pulses 11a and 11b (an example of a pulse signal) and current control signals 12a and 12b to drive drivers 8a and 8b. It is composed of a control section 7 (an example of a control section) and motors 9a and 9b (an example of a stepping motor) driven by driving drivers 8a and 8b (an example of a motor driver).
Motors 9a and 9b, which are examples of the stepping motor, move in the direction of the camera (here, the sensor / lens unit 6).
Driving drivers 8a and 8b, which are examples of a motor driver, receive a pulse signal and a current control signal for controlling a current value flowing to the motors 9a and 9b, and use the input pulse signal and the current control signal to input the pulse signal and the current control signal. The motors 9a and 9b are driven.
The turntable control unit 7, which is an example of the control unit, generates the pulse signal and the current control signal, and outputs the generated pulse signal and the current control signal to the driving drivers 8a and 8b to generate the pulse signal and the current control signal. Controls camera orientation movement.
[0010]
FIG. 2 is a diagram specifically showing the drive pulses 11a and 11b and the current control signals 12a and 12b in the first embodiment.
In FIG. 2, diagrams 13a and 13b are diagrams showing signal contents of the driving pulse 11a or the driving pulse 11b at the time of microstep driving. For example, when the signal content state of the drive pulse 11a is the diagram 13a in FIG. 2, the diagram 14a has a stepped shape corresponding to the state of the diagram 13a (that is, for example, the drive pulse 11a here). FIG. 9 is a diagram illustrating a signal content state of a current control signal 12a (for example, in the case of a drive pulse 11b, a current control signal 12b). A diagram 15a is a diagram showing a motor current waveform when controlled by a current control signal (here, the current control signal 12a, ie, diagram 14a). A diagram 16a is a diagram showing the motor behavior when controlled by the current control signal (here, the current control signal 12a, ie, diagram 14a). A diagram 14b is a diagram showing a signal content state of the current control signal 12a (for example, in the case of the drive pulse 11b, the current control signal 12b) when the current control signal is not controlled in a stepwise manner. Diagrams 15b and 16b show the motor current waveform and motor behavior when controlled by the current control signal (here, the current control signal 12a, ie, diagram 14b).
[0011]
The current control signals 12a and 12b have predetermined values. Here, the predetermined value corresponds to the value of each point in the diagram 14a.
The turntable control unit 7, which is an example of the control unit, generates the current control signals 12a and 12b so that the predetermined value increases stepwise.
The turntable control unit 7, which is an example of the control unit, controls the pulse signal and the current so that the current control signal 12a starts to increase stepwise in synchronization with the drive pulse 11a, which is an example of the pulse signal. And a control signal.
In other words, the surveillance camera device 1 includes a turntable driven by a stepping motor, a motor driver for driving the stepping motor, and a mechanism for controlling a current control signal input to the motor driver. Changes the current control signal stepwise between microstep driving pulses when the motor driver is driven in microsteps. That is, the surveillance camera device 1 includes a turntable driven by a stepping motor, a motor driver for driving the stepping motor, and a unit for controlling a current control signal input to the motor driver. Means for changing the current control signal in a stepwise manner between microstep drive pulses during driving is provided.
[0012]
Next, the entire operation will be described more specifically. Surveillance camera device 1 receives turntable operation command 4 from an external control device and inputs it to camera control unit 5, and camera control unit 5 outputs operation command 10 to turntable control unit 7. In response to the operation command 10, the turntable control unit 7 drives the drive drivers 8a and 8b to drive pulses 11a and 11b, current control signals 12a and 12b, a rotation direction control signal (not shown), and a mode switching signal (not shown). (Not shown) and outputs them to the driving drivers 8a and 8b, respectively. Thereby, the motors 9a and 9b are driven.
[0013]
Next, the operation of reducing the motor rotational vibration of the current control signal 12a (diagram 14a) generated stepwise in FIG. 2 will be described. A driving pulse 11a (diagram 13a) at the time of micro-step driving in FIG. 2 is input to the driving drivers 8a and 8b in FIG. 1, and a current control signal 12a (diagram 14a) controlled stepwise correspondingly is input. When input, the drive pulse 11a (diagram 13b) at the time of microstep driving is input, and the motor angle is switched by the drive pulse as compared with the case where the current control signal 12a (diagram 14b) which is not controlled in a stepwise manner is input. In this case, the rise of the current waveform becomes gentler as shown in a diagram 15a of the motor current, whereby the behavior of the motor becomes as shown in a diagram 16a, and the vibration is reduced as compared with the diagram 16b.
[0014]
As described above, the technology for changing the excitation position and the excitation balance of the phase using the current control signal controlled in a stepwise manner, that is, instead of changing the microstep itself, suppresses the inrush current at the time of starting the motor and reduces the vibration. Can be reduced.
[0015]
The turntable control unit 7, which is an example of the control unit, sets the predetermined values of the generated current control signals 12a and 12b in a stepwise manner according to the moving speed for moving the direction of the camera. At least one of the timing and the level of the predetermined value is changed. That is, the timing or level of the staircase shape of the current control signal is changed according to each operation speed of the turntable. For changing the step-like timing, for example, when the moving speed of the camera is slow, that is, when the input pulse timing is late, by switching at a later timing, the time to reach the final current value is increased. The vibration is further suppressed and the vibration is hardly seen in the image. As for changing the level of the predetermined value, for example, if a control signal is generated so as to change the current value small at one timing, the number of times of changing the current value in a stepwise manner to reach the final current value is increased. The time to reach the final current value can be lengthened, and the same effect as described above can be obtained.
Further, the turntable control unit 7, which is an example of the control unit, generates predetermined values of the generated current control signals 12a and 12b in a stepwise manner in accordance with a moving speed for moving the direction of the camera. It switches between the case and the case where it is not generated stepwise. In other words, the presence or absence of the step control of the current control signal is switched according to each operation speed of the turntable. Regarding the elimination of the step-like control, for example, when the camera moving speed is higher than a certain speed, it becomes difficult to visually recognize the vibration without using the step-like control.
[0016]
Here, in Patent Document 1 (FIG. 3 of Japanese Patent Application Laid-Open No. 1-218395) shown as a conventional example, there is a case where a step-like additional pulse is input by a mini-step (micro-step) drive input pulse. Is a technique in which the resolution itself of the motor is subdivided by an additional pulse to reduce vibration, and a so-called microstep for changing the stable position itself of each phase of the motor more finely is further subdivided. For example, in the conventional example, the static angle of the motor in the first step of the step-like additional pulse is different from the angle in the first step of the micro-step input pulse. In this embodiment, only the current control signal is changed stepwise, so that the stable position of each phase of the motor is the same regardless of the presence or absence of the step. For example, the static motor angle in the first step 17a of the current control waveform generated stepwise in FIG. 2 is the same as that in step 17b.
[0017]
【The invention's effect】
As described above, the surveillance camera device of the present invention is configured so that the current control signal is changed stepwise between the microstep driving pulses during the microstep driving of the motor driving driver. An effect that a surveillance camera device having a configuration and a small size can be obtained, and is not restricted by a control microcomputer or the like, and has sufficiently small vibration during rotation even when an existing standard motor driver is used. There is. Further, not only the vibration when continuously rotated, but also the vibration at the time of stabilization is reduced, so that there is an effect that a surveillance camera device having a small vibration when the rotation is stopped is obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a surveillance camera device according to a first embodiment.
FIG. 2 is a diagram specifically showing drive pulses 11a and 11b and current control signals 12a and 12b in the first embodiment.
[Explanation of symbols]
Reference Signs List 1 surveillance camera device, 2 camera unit, 3 turntable unit, 4 command signal, 5 camera control unit, 6 sensor / lens unit, 7 turntable control unit, 8a, 8b drive driver, 9a, 9b motor, 10 operation command , 11a, 11b drive pulse, 12a, 12b current control signal.

Claims (5)

A stepper motor that moves the camera,
A motor driver that inputs a pulse signal and a current control signal for controlling a current value flowing to the stepping motor, and drives the stepping motor using the input pulse signal and the current control signal;
A control unit that generates the pulse signal and the current control signal, and outputs the generated pulse signal and the current control signal to the motor driver to control movement of the camera. Camera moving device. The current control signal has a predetermined value,
The camera moving device according to claim 1, wherein the control unit generates the current control signal so that the predetermined value increases in a stepwise manner. 3. The camera moving device according to claim 2, wherein the control unit generates the pulse signal and the current control signal such that the current control signal starts increasing stepwise in synchronization with the pulse signal. . The control unit may change at least one of a step-like timing and a level of the predetermined value for the predetermined value to be generated according to a moving speed for moving the direction of the camera. The camera moving device according to claim 1, wherein: The control unit switches between a case where the predetermined value to be generated is generated in a stepwise manner and a case where the predetermined value is not generated in a stepwise manner according to a moving speed for moving the direction of the camera. 2. The camera moving device according to 1.

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