JP4340080B2 - Camera moving device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a monitoring camera device capable of directing a camera for monitoring by turning of a turntable in an arbitrary direction, and particularly to reduction of rotational vibration at the time of microstep drive of a turntable drive motor.
[0002]
[Prior art]
As a conventional technique, there is the following technique as a technique for changing the excitation position and the excitation balance of the phases, that is, the technique of the microstep itself.
[0003]
As a technology for changing the excitation position, a conventional stepping motor mini-step (synonymous with microstep) drive device generates a predetermined number of additional pulses for each input pulse in order to reduce rotational vibration during microstep drive. And an excitation signal corresponding to 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]
The following means for providing a stepping motor driving device capable of performing smooth driving with small torque fluctuation while maintaining the step angle as a technique for bringing the torque closer to the ideal torque, that is, changing the excitation balance of the phases. It is publicly known. A plurality of drivers that have a plurality of magnetically coupled phase coils and that sequentially drive the phase coils to excite them, and compare the current control reference signal with each phase coil current equivalent signal, and send a constant current control signal to each driver. In a stepping motor drive device having a plurality of comparators for output and a control circuit for generating a phase switching signal to be applied to each driver, the level of each current control reference signal input to each comparator is switched in a plurality of stages. In addition to providing a level switching means that can be formed, and when switching excitation from one phase coil that is not magnetically coupled to the other phase coil, the phase coil current of the one phase coil is decreased stepwise and the phase of the other phase coil is reduced. The level switching means has a predetermined procedure 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, an additional pulse generator must be provided to reduce the rotational vibration of the surveillance camera device, which increases the circuit scale and the substrate. There was a problem that a device became large and a small device could not be obtained. Further, since the excitation signal is switched by the additional pulse, the additional pulse timing becomes high speed, and there is a problem that a sufficient effect cannot be obtained due to the restriction of the pulse timing by the control microcomputer or the like. If the microstep resolution itself is further subdivided by additional pulses, and it is necessary to further reduce 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 eliminates the need for providing an additional pulse generator, and thus can provide a small surveillance camera device, is not limited by a control microcomputer, and can be rotated even when an existing standard motor driver is used. An object is to obtain a surveillance camera device with low 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 the camera;
A motor driver that inputs a pulse signal and a current control signal that controls a current value that flows through the stepping motor, and that 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 the movement of the camera. And
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating a surveillance camera device according to the first embodiment.
In FIG. 1, the monitoring camera device 1 includes a camera unit 2 that captures a monitoring video and a turntable unit 3 (an example of a camera moving device) that directs 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 pulse signals) and current control signals 12a and 12b to drive drivers 8a and 8b. The motor 9a and 9b (an example of a stepping motor) are driven by a control unit 7 (an example of a control unit) and driving drivers 8a and 8b (an example of a motor driver).
Motors 9a and 9b, which are examples of stepping motors, move the direction of the camera (here, the sensor / lens unit 6).
Driving drivers 8a and 8b, which are examples of motor drivers, input a pulse signal and a current control signal for controlling a current value flowing through the motors 9a and 9b, and use the input pulse signal and the current control signal. The motors 9a and 9b are driven.
The turntable controller 7, which is an example of a controller, 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. Control the movement of the camera orientation.
[0010]
FIG. 2 is a diagram specifically showing drive pulses 11a and 11b and current control signals 12a and 12b in the first embodiment.
In FIG. 2, diagrams 13a and 13b are diagrams showing signal contents of the drive pulse 11a or the drive pulse 11b during microstep driving. For example, when the signal content state of the drive pulse 11a is the diagram 13a in FIG. 2, the diagram 14a is stepped corresponding to the state of the diagram 13a (that is, for example, the drive pulse 11a here). It is a diagram showing the signal content state of the current control signal 12a (for example, in the case of the drive pulse 11b, the 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, that is, the diagram 14a). A diagram 16a is a diagram showing a motor behavior when controlled by a current control signal (here, the current control signal 12a, that is, the diagram 14a). The diagram 14b is a diagram showing a signal content state of the current control signal 12a (for example, the current control signal 12b in the case of the drive pulse 11b) when the current control signal is not controlled stepwise. A diagram 15b and a diagram 16b respectively show a motor current waveform and a motor behavior when controlled by a current control signal (here, the current control signal 12a, that is, the diagram 14b).
[0011]
The current control signals 12a and 12b have a predetermined value. Here, the predetermined value corresponds to the value of each point in the diagram 14a.
The turntable controller 7, which is an example of the controller, generates the current control signals 12a and 12b so that the predetermined value increases stepwise.
Then, the turntable controller 7, which is an example of the controller, synchronizes with the drive pulse 11a, which is an example of the pulse signal, so that the current control signal 12a starts to increase stepwise. And a control signal.
In other words, the monitoring camera device 1 includes a rotating table 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 drive pulses during microstep drive of the motor driver. That is, the monitoring camera device 1 includes a turntable driven by a stepping motor, a motor driver for driving the stepping motor, and a means for controlling a current control signal input to the motor driver, and the microstep of 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. The monitoring camera device 1 receives a turntable operation command 4 from an external control device and inputs it to the camera control unit 5, and the camera control unit 5 outputs an operation command 10 to the turntable control unit 7. Upon receiving the operation command 10, the turntable control unit 7 drives the driving 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) are generated and output to the driving drivers 8a and 8b, respectively. Thereby, the motors 9a and 9b are driven.
[0013]
Next, the motor rotation vibration reducing operation 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 microstep 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 corresponding to the driving pulse 11a. When input, the driving pulse 11a (diagram 13b) at the time of microstep driving is input, and the motor angle is switched by the driving pulse as compared with the case where the current control signal 12a (diagram 14b) not controlled stepwise is input. When the current waveform rises, the motor current waveform becomes gentle as shown in the diagram 15a, whereby the behavior of the motor becomes as shown in the diagram 16a, and vibration is reduced compared to the diagram 16b.
[0014]
As described above, the technology that changes the excitation position and the excitation balance of the phases by the current control signal controlled stepwise, that is, the micro step itself is not changed, and the inrush current at the start of the motor is suppressed and the vibration is suppressed. Can be reduced.
[0015]
Further, the turntable control unit 7 which is an example of the control unit makes a step for the predetermined values of the current control signals 12a and 12b to be generated 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 example, if the moving speed of the camera is slow, that is, if the input pulse timing is slow, the time to reach the final current value can be increased by switching at a slower timing. The vibration is further suppressed, and the vibration is less visible on the image. About changing the level of the predetermined value, for example, if the control signal is generated so as to change the current value small at a single timing, the number of times of changing the step to reach the final current value can be increased. The time for reaching the final current value can be increased, 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 current control signals 12a and 12b to be generated in a stepped manner in accordance with a moving speed for moving the direction of the camera. Switching between the case and the case where it is not generated stepwise. In other words, the presence / absence of the step-like 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 is difficult to visually see the vibration without using the step-like control.
[0016]
Here, in Patent Document 1 shown in the conventional example (FIG. 3 of JP-A-1-218395), there is an example in which a stepwise additional pulse is input by an input pulse of ministep (microstep) driving. In this example, the resolution of the motor itself is subdivided by additional pulses to reduce vibrations, and so-called microsteps for changing the stable position of each phase of the motor more finely are further subdivided. For example, in the conventional example, the static angle of the motor in the first step of the stepwise additional pulse is different from the angle in the first step of the microstep 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 shape. 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 monitoring camera device of the present invention is configured to change the current control signal in a stepwise manner between microstep drive pulses during microstep drive of the motor drive driver. Advantages of obtaining a surveillance camera device with a configuration that is small and that is not subject to the restrictions of a control microcomputer, etc., and that even when using an existing standard motor driver, vibration during rotation is sufficiently small There is. In addition to reducing the vibration when rotating continuously, the vibration at the time of settling is also reduced, so there is an effect that a monitoring camera device with a small vibration at the time of stopping rotation can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a monitoring 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]
DESCRIPTION OF SYMBOLS 1 Surveillance camera apparatus, 2 camera part, 3 turntable part, 4 command signal, 5 camera control part, 6 sensor / lens part, 7 turntable control part, 8a, 8b drive driver, 9a, 9b motor, 10 operation command , 11a, 11b Drive pulse, 12a, 12b Current control signal.

Claims (3)

A stepping motor that operates the motor one step at a time when one pulse is input, wherein the stepping motor moves the direction of the camera by microstep driving in which the one step is divided into a plurality of microsteps ;
A current control signal that generates and outputs a microstep drive pulse signal for each microstep, and that increases stepwise from the initial value to a predetermined value within the generated microstep drive pulse signal. A control unit that generates and outputs a current control signal that controls a current value flowing through the motor;
The microstep drive pulse signal output from the control unit and the current control signal are sequentially input, and the stepped motor is input so that the value of the current flowing through the stepping motor increases gradually each time the microstep drive pulse signal is input. And a motor driver for driving the stepping motor by controlling a current value to be supplied to the stepping motor in accordance with a value of a current control signal which increases to a maximum . The controller controls the current control signal from the predetermined value when generating the microstep driving pulse signal so that the current control signal increases stepwise from the initial value to the predetermined value within the microstep driving pulse signal. returned to the initial value, the camera moving device according to claim 1, wherein generating a larger current control signal stepwise again from the initial value until the predetermined value. Wherein the control unit, according to the moving speed for moving the orientation of the camera, the timing at which the current control signal increases stepwise in between the micro-step drive pulse signal, in between the micro-step drive pulse signal 3. The camera moving device according to claim 1, wherein at least one of the number of steps when the current control signal increases stepwise is changed.

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