JP4493510B2 - Camera turning device - Google Patents

Description

  The present invention relates to a camera turning device, and more particularly to a camera turning device for turning a camera by a stepping motor, for example.

Conventionally, for example, this type of camera turning device is disclosed in Patent Document 1. According to this prior art, the rotational speed or drive current of the stepping motor is controlled in accordance with changes in external conditions such as wind and temperature. Thereby, the torque shortage of the stepping motor at the time of driving (turning) due to the change of the external condition is resolved, and the stepping motor is prevented from being stepped out.
JP 2001-128033 A

  By the way, in the camera turning device as described above, a step-out may occur not only when the stepping motor is driven but also when it is stationary (when turning is stopped). This step-out when stationary occurs mainly due to vibration applied to the stepping motor. And when a step-out occurs in a stationary state as described above, the camera orientation changes, which is a particularly fatal problem for monitoring applications.

  Therefore, an object of the present invention is to provide a camera turning device that can accurately fix the orientation of the camera when turning is stopped.

In order to achieve such an object, the present invention provides a camera turning device for turning a camera by a stepping motor, a detection means for generating an output signal related to vibration applied to the stepping motor, and an output signal of the detection means And a control means for controlling the torque when the stepping motor is stationary .

That is, according to the present invention, when vibration is applied to the stepping motor, an output signal related to the vibration is generated by the detection means. And based on the output signal of this detection means, a control means controls the torque of a stepping motor. Specifically, the control means performs control so that the greater the vibration applied to the stepping motor, the greater the torque when the stepping motor is stationary . That is, the greater the vibration applied to the stepping motor, the greater the static torque applied to the stepping motor. Then, by applying such a large static torque, the stepping motor can be prevented from stepping out when stationary.

  The control means in the present invention may control the static torque by adjusting the current supplied to the stepping motor.

  The present invention is particularly effective for a structure in which the driving force of the stepping motor is transmitted to the camera via a belt-type transmission means. That is, generally known transmission means include, for example, a belt type and a gear type. The gear type has a larger friction coefficient than the belt type. Therefore, for example, when a gear type is adopted as the transmission means, the friction of the transmission means itself greatly contributes to maintaining the stationary state of the stepping motor. On the other hand, when the belt-type transmission means is employed, the contribution of the friction cannot be expected as the gear type. Therefore, the stepping motor becomes easier to step out accordingly. The present invention is particularly effective in the case where the belt-type transmission means that is easy to be stepped out is employed.

  According to this invention, the greater the vibration applied to the stepping motor, the greater the static torque applied to the stepping motor. By applying such a large static torque, the stepping motor is prevented from stepping out when stationary, and the orientation of the camera when turning is stopped is accurately fixed.

  An embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the surveillance camera device 10 according to this embodiment is a so-called dome type camera having a dome-shaped window member 12, and a cover 14 including the window member 12 is shown inside FIG. 2. Thus, a CCD (Charge Coupled Device) type camera 16 and a turntable 18 for turning the camera 16 are provided. Of these, the camera 16 includes a zoom lens 20 and also has an autofocus function.

  On the other hand, the swivel base 18 turns the camera 16 in the vertical direction (elevation) as shown by an arrow 100 in FIG. 2, that is, tilts it, and also turns the camera 16 as shown by an arrow 102. Can also be swung in the horizontal (azimuth) direction, that is, panned. Therefore, the swivel base 18 is separately provided with a 5-phase stepping motor 22 for tilting and a 5-phase stepping motor 24 for panning (see FIG. 5).

  Specifically, the swivel base 18 has a holding means for holding the camera 16, for example, a head portion 26, and a tilting stepping motor 22 has its rotation axis in the horizontal direction. Attached in a stretched state. A pulley (small pulley) 28 is attached to the rotating shaft of the stepping motor 22, and this small pulley 28 is connected to another pulley (large pulley) via a toothed belt 30 as shown in FIG. ) 32. The large pulley 32 is also attached to the head portion 26, and the camera 16 is fixed to the large pulley 32 so that the central axis of the large pulley 32 and the optical axis of the camera 16 are perpendicular to each other. . Accordingly, when the tilting stepping motor 22 is driven, the driving force is transmitted to the camera 16 via the transmission mechanism 34 including the small pulley 28, the belt 30 and the large pulley 32. As a result, the camera 16 rotates about the axis along the horizontal direction (the central axis of the large pulley 32), and a tilting operation is realized.

  On the other hand, the stepping motor 24 for bread is provided in the base portion 36 constituting the swivel base 18 with its rotating shaft extending in the vertical direction, although not shown in detail. In the base portion 36, a transmission mechanism similar to that described above is configured using the bread stepping motor 24 as a drive source. And the head part 26 is being fixed to this transmission mechanism (large pulley). Accordingly, when the panning stepping motor 24 is driven, the driving force is transmitted to the head unit 26 via the transmission mechanism. As a result, the head unit 26 rotates together with the camera 16 about the axis (the chain line in FIG. 2) along the vertical direction, and the pan operation is realized.

  The monitoring camera device 10 configured in this way is used to monitor an outdoor parking lot or a park, for example. In this case, as shown in FIG. 4, the monitoring camera device 10 may be mounted on a pole 202 installed perpendicular to the ground 200. The monitoring camera device 10 is connected to a controller and a monitor device (not shown) installed in a building such as a management room (not shown). When the controller is operated, a control signal corresponding to the operation content is sent from the controller to the monitoring camera device 10, and the tilt operation and pan operation described above are controlled according to the control signal. The operation of the zoom lens 20 is also controlled according to the control signal. Then, the surveillance camera device 10 outputs a video signal representing a captured video, and this video signal is sent to the monitor device. As a result, a monitoring image is displayed on the screen of the monitor device.

  By the way, when the surveillance camera device 10 is installed outdoors as described above, especially when attached to an elastic object such as the pole 202, for example, a large vehicle such as a truck passes in the vicinity thereof, Vibration may be applied to the monitoring camera device 10. In addition, when a relatively strong wind blows, the pole 202 may be shaken by the wind, and the vibration may be transmitted to the surveillance camera device 10. Then, the vibration applied to the monitoring camera device 10 as described above is naturally transmitted to the above-described stepping motors 22 and 24 inside the monitoring camera device 10, which may cause the stepping motors 22 and 24 to step out. If the step-out occurs in this way, particularly when the stepping motors 22 and 24 are stationary, the direction of the camera 16 is changed, which may hinder the monitoring operation.

  In view of this, in the monitoring camera device 10 of this embodiment, in order to prevent the stepping motors 22 and 24 from stepping out when stationary, and thus to accurately fix the orientation of the camera 16 when turning is stopped, the following measures are taken. Is made.

  That is, as shown in FIG. 4, the vibration sensor 300 is provided in the vicinity of the monitoring camera device 10. The vibration sensor 300 is for detecting vibration applied to the monitoring camera device 10, and hence vibration applied to the stepping motors 22 and 24, and is realized by, for example, a gyroscope. The output signal of the vibration sensor 300, that is, the sensor output signal, is input to the monitoring camera device 10, and specifically, input to the control board 50 as shown in FIG.

  The control board 50 is provided in the base portion 36 described above, and a CPU (Central Processing Unit) 52 is mounted on the control board 50. The sensor output signal is input to the CPU 52 via an input / output interface (hereinafter referred to as I / O) circuit 54. The control signal is also input to the CPU 52 via the I / O circuit 54.

  For example, when the control signal indicates a tilt operation, the CPU 52 performs constant current control of the tilting stepping motor 22 via the tilt drive circuit 56 in accordance with this instruction. As a result, the stepping motor 22 is driven by a so-called trapezoidal acceleration / deceleration method to perform a tilting operation.

  When the control signal indicates, for example, a panning operation, the CPU 52 performs constant current control of the panning stepping motor 24 via the panning drive circuit 58 in accordance with this instruction. As a result, the stepping motor 24 is driven by a trapezoidal acceleration / deceleration method to perform a pan operation.

  Further, when the control signal indicates, for example, a zoom operation, the CPU 52 controls the zoom lens 20 of the camera 16 according to this instruction (strictly speaking, a CPU (not shown) is also mounted in the camera 16). The CPU controls the zoom lens 20 in accordance with a command given from the CPU 52 on the control board 50 side). As a result, the zoom lens 20 is driven and a zoom operation is performed.

  Further, the CPU 52 calculates the magnitude of the vibration applied to each of the stepping motors 22 and 24, that is, the vibration level L based on the above-described sensor output signal together with the control according to these control signals. Based on this calculation result L, the magnitude of the current supplied to each of the stepping motors 22 and 24 is controlled.

  Specifically, the CPU 52 compares the vibration level L described above with a predetermined reference level α. The reference level α referred to here is a level serving as a determination criterion for determining whether or not each of the stepping motors 22 and 24 may step out of the vibration level L, that is, a threshold value. For example, when the rated current is supplied to each of the stepping motors 22 and 24, the upper limit value of the vibration level L that can be considered that the stepping motors 22 and 24 will not step out is the reference level. Set as α. Here, when the vibration level L is larger than the reference level α (L> α), that is, when there is a possibility that the stepping motor 22 or 24 will step out only by the supply of the rated current, the CPU 52 determines the rated current from the rated current. Each of the drive circuits 56 and 58 is controlled so that a larger current, for example, a current as large as 40 [%] is supplied to the respective stepping motors 22 and 24. As a result, the control torque of each stepping motor 22 and 24 is increased, and the step-out of each stepping motor 22 and 24, particularly the step-out when stationary, is prevented.

  On the other hand, when the vibration level L is below the reference level α (L ≦ α), that is, when there is no possibility that the stepping motors 22 and 24 will step out even when only the rated current is supplied, the CPU 52 may step out. The drive circuits 56 and 58 are controlled such that a current smaller than a certain time, for example, a current larger by 20 [%] than the rated current is supplied to the respective stepping motors 22 and 24. Even when there is no possibility of step-out in this way, a current larger than the rated current is supplied to the stepping motors 22 and 24 because the driving force of the stepping motors 22 and 24 is reduced. This is because a belt type like the transmission mechanism 34 described above is employed as the transmission means for transmitting.

  That is, as a generally known transmission means, there is a gear type in addition to the belt type. The gear type has a larger friction coefficient than the belt type. Therefore, for example, when a gear type is used as the transmission means, the friction of the transmission means itself greatly contributes to maintaining the stationary state of the respective stepping motors 22 and 24. Therefore, step-out is less likely to occur. On the other hand, with the belt type, the effect of such friction cannot be expected as with the gear type. Accordingly, the stepping motors 22 and 24 are easily stepped out accordingly, and in order to compensate for this, a current larger than the rated current is supplied even when there is no possibility of stepping out as described above.

  In order to control the current supplied to the stepping motors 22 and 24 based on the vibration level L in this way, the CPU 52 controls the current control shown in the flowchart of FIG. 6 according to the control program stored in the memory circuit 60. Execute the task.

  That is, the CPU 52 first acquires a sensor output signal from the vibration sensor 300 in step S1. At this time, the sensor output signal may be smoothed by averaging or integrating the sensor output signal. In step S3, after calculating the vibration level L from the sensor output signal, the process proceeds to step S5, where the vibration level L is compared with the reference level α.

  Here, when the vibration level L is larger than the reference level α, the CPU 52 proceeds to step S7. In step S7, the magnitude of the current supplied to each of the stepping motors 22 and 24 is set to +40 [%] (1.4 times) of the rated current. As a result, the torque of the stepping motors 22 and 24 becomes larger than the rating. And after execution of this step S7, it returns to step S1.

  On the other hand, when the vibration level L is below the reference level α, the CPU 52 proceeds from step S5 to step S9. In step S9, the magnitude of the current supplied to each stepping motor 22 and 24 is set to +20 [%] of the rated current. As a result, the torque of the stepping motors 22 and 24 becomes smaller (larger than the rating) compared to the case of step S7 described above. And after execution of this step S9, it returns to step S1.

  As described above, according to this embodiment, the vibration sensor 300 detects the level L of vibration applied to the stepping motors 22 and 24. When the vibration level L is high enough to cause the stepping motors 22 and 24 to step out, a current of +40 [%] of the rated current is supplied to the stepping motors 22 and 24. As a result, the stepping motors 22 and 24 are prevented from stepping out, and in particular, stepping out when stationary is prevented. And if it sees as the surveillance camera apparatus 10 whole, direction of the camera 16 at the time of a turning stop is fixed exactly.

In this embodiment, the magnitude of the current supplied to each of the stepping motors 22 and 24 is set in two stages of +40 [%] and +20 [%] of the rated current, but is not limited thereto. For example, it may be set finely in three or more steps, and the magnitude of the current may be controlled continuously (linearly or curvedly) according to the vibration level L. However, if this current is too large, the stepping motors 22 and 24 generate heat, the temperature in the monitoring camera device 10 rises, and each electronic component including the stepping motors 22 and 24 is adversely affected. In consideration of this, it is important to determine the upper limit value of the current supplied to the stepping motors 22 and 24.

  Further, in this embodiment, the magnitude of the current supplied to each of the stepping motors 22 and 24 is the same both during driving and at rest, but this is not restrictive. That is, the magnitude of the current supplied during driving may be different from the magnitude of the current supplied during rest. Further, although the stepping motors 22 and 24 are controlled with constant current, they may be controlled with constant voltage. And although the 5-phase type thing was used as the said stepping motors 22 and 24, you may employ | adopt things other than this.

  Furthermore, although the camera 16 can be turned in both the tilt and pan directions, the camera 16 may be turned in only one direction of the tilt and pan. Of course, only one stepping motor is sufficient in this case.

  Moreover, although the vibration sensor 300 was provided in the vicinity of the monitoring camera apparatus 10, it is not restricted to this. For example, the vibration sensor 300 may be directly attached to the monitoring camera device 10 or may be disposed in the monitoring camera device 10.

  Further, the vibration applied to the monitoring camera device 10 may be detected by a detection means other than the vibration sensor 300. For example, a means for detecting wind speed such as an anemometer is provided, the vibration level L is indirectly calculated from the detection result, and the current supplied to the stepping motors 22 and 24 is controlled from the calculation result L. It may be. Further, when an anemometer is already provided for another purpose before the monitoring camera device 10 is installed, the anemometer can be used. Furthermore, in view of the fact that the wind is likely to become stronger when the low pressure approaches, a means for detecting atmospheric pressure such as a barometer is provided, and the vibration level L predicted from the detection result of the atmospheric pressure is set. The current supplied to the stepping motors 22 and 24 may be controlled from the vibration level L.

  In addition, the content demonstrated by this embodiment is an example for implement | achieving this invention until it gets tired, and this invention is not limited.

It is a perspective view which shows the external appearance of the surveillance camera apparatus which concerns on one Embodiment of this invention. It is a figure which shows the state by which the cover was removed in FIG. It is a figure which shows the state from which the camera was further removed in FIG. It is an illustration figure which shows the example of installation of the monitoring camera apparatus. It is a block diagram which shows the electrical structure of the monitoring camera apparatus. It is a flowchart which shows the content of the current control task which CPU in the monitoring camera apparatus performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Surveillance camera apparatus 16 Camera 18 Turntable 22, 24 Stepping motor 52 CPU
60 memory circuit 300 vibration sensor

Claims (1)

In a camera turning device for turning a camera by a stepping motor,
Vibration detecting means for generating an output signal related to vibration applied to the stepping motor;
Control means for controlling the torque so that the torque at rest of the stepping motor is increased by increasing the current supplied to the stepping motor as the vibration is larger based on the output signal;
A camera turning device characterized by comprising:

Images