JP2011008193A - Ptz camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PTZ (pan tilt zoom) camera system having a stable highly precise PTZ operation over a long period time, in simple constitution.SOLUTION: The PTZ camera system includes: a turn-driving motor 11, a first driving worm 13 rotation-driven by the motor 11, a worm wheel 14 meshed with the worm 13 to turn a camera body 4, a backlash-preventive second worm 16 provided in parallel to the first worm 13 and meshed with the worm wheel 14, rotation transmitting means 15a, 15b for transmitting the rotation of the first worm 13 reverse-directional-rotationally to the second worm 16, and a pressing means 17 for pressing the second worm 16 toward a direction of meshing with the worm wheel 14, when the rotation of the worm wheel 14 stops.

Description

  The present invention relates to a turning camera system including a camera and a turning drive mechanism for turning the camera.

  A video surveillance system called CCTV (Closed Circuit TeleVision) or ITV (Industrial TeleVision) that centrally monitors specific locations and facilities from the center side makes appropriate judgments in situations such as accidents, disasters, and abnormal situation checks. , Play a big role in responding quickly. For this type of video surveillance system, an integrated camera system in which a turning drive mechanism for turning the camera and the camera and a communication unit are integrally provided is widely applied. This type of turning camera system has a function of turning the camera in a direction stored in advance by external control. When a worm gear with a large gear ratio (reduction ratio) that can obtain a large driving torque is used for this turning drive mechanism, so-called drive backlash occurs due to backlash of the gear, and this backlash (gear backlash) ) Is a factor that hinders the accuracy of setting the angle of view.

  As a technique for solving this problem, conventionally, in a turning drive device using a worm gear applied to a turning camera system, when turning is stopped (when rotation transmission of the worm and the worm wheel is stopped), a pressing force generating member is used. There is a technology that presses the worm against the worm wheel to reduce the gap (backlash) between the worm and the worm wheel, and releases the pressing by the pressing force generating member during turning (when the rotation is transmitted) (Patent Document 1). ).

  However, this backlash prevention technology has a problem that performance is greatly affected by the pressing timing of the pressing force generating member, and stable and reliable operation cannot be expected. There is a problem that load is applied.

  In addition, when the worm is constantly pressed against the worm wheel, the friction accompanying this pressing always occurs, so a large motor with a large driving torque is required as the driving source, which leads to an increase in the size of the device and is stable. There is a problem that a highly reliable operation cannot be expected.

  As another technique, a worm base that rotatably supports a worm has a guide mechanism for moving in a normal direction perpendicular to the axis of the worm wheel, and the worm acts on the tooth surface of the worm wheel. There has been a technique of pressing in the linear direction and maintaining the distance between the worm and the worm wheel within a predetermined range (Patent Document 2).

  However, this backlash prevention technology requires a mechanism that always keeps the distance between the worm and the worm wheel within a certain range in a stable state, which makes the structure complicated, unreliable, and practical. There is a problem in terms of.

JP 2004-279758 A JP 2004-108443 A

  As described above, in a turning camera system that integrally has a turning drive device using a worm gear, conventionally, a camera turning drive mechanism equipped with a highly practical backlash prevention technology that can be expected to operate stably for a long period of time is provided. There was a problem that it did not exist.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a turning camera system that can expect a stable and accurate turning operation for a long period of time with a simple configuration.

  The present invention provides a turning camera system comprising a surveillance camera and a turning drive mechanism for turning the camera, wherein the turning drive mechanism includes a turning drive motor, and a first drive for rotation driven by the motor. 1 worm, a worm wheel that meshes with the first worm and drives the camera to pivot, and a second for preventing backlash that is provided in parallel with the first worm and meshes with the worm wheel. , A rotation transmitting means for transmitting rotation of the first worm in the reverse direction to the second worm, and when the rotation of the worm wheel is stopped, the second worm is meshed with the worm wheel. And a pressing means for pressing in the axial direction.

  According to the present invention, a highly accurate turning operation that is stable over a long period of time can be expected with a simple configuration.

It is a figure which shows the structure of the turning drive mechanism of the turning camera system which concerns on one Embodiment of this invention. It is a figure which shows the external appearance structure of the turning camera system which concerns on the embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration of a turning drive mechanism of a turning camera system according to an embodiment of the present invention, and FIG. 2 shows an external structure of a turning camera system that is driven and controlled by the turning drive mechanism. In addition, in FIG. 1, about the attachment structure of each component, and the rotation support mechanism, the specific structure is abbreviate | omitted and shown.

  As shown in FIG. 1, the turning drive mechanism of the turning camera system according to the embodiment of the present invention includes a turning drive motor 11, a drive first worm 13 that is driven to rotate by the motor 11, A worm wheel 14 that meshes with the first worm 13 and rotates the camera (camera body) 4 shown in FIG. 2, and a back that is provided in parallel with the first worm 13 and meshes with the worm wheel 14. When the rotation of the second worm 16 for preventing rush, the rotation transmitting means 15a and 15b for transmitting the rotation of the first worm 13 in the reverse direction to the second worm 16, and the rotation of the worm wheel 14 are stopped. The second worm 16 is pressed in the axial direction to mesh with the worm wheel 14 (the worm wheel 1 with which the first worm 13 (screw thread) contacts). Against tooth surfaces (a), it is pressed in the thrust direction (P) in contact with the tooth surface on the opposite side (b)) formed by and a pressing means 17.

  The turning camera system controlled to be turned by the turning drive mechanism 5 shown in FIG. 1 is a waterproof turning camera system capable of endless turning according to outdoor environment specifications. As shown in FIG. The driving unit 2, the camera unit unit 3, and the camera (camera body) 4 are provided.

  On the base 1 of the turning camera system, a camera body 4 provided in the camera unit 3 is supported by the turning drive unit 2 so as to be able to turn horizontally (left and right) and vertically (up and down). Realizes a surveillance camera without vertical blindness of ± 90 °. In the figure, L1 is a horizontal (left-right direction) pivot drive axis center, L2 is a vertical (vertical direction) pivot drive axis center, and the pivot drive unit 2 is a direction orthogonal to each other for driving the camera unit 3 to pivot. 2 has two swivel drive shafts (see reference numeral 10 shown in FIG. 1). That is, the turning drive unit 2 is individually provided with a turning drive mechanism for horizontally turning the camera unit 3 and a turning drive mechanism for vertically turning the camera unit 3, and each turning drive thereof is provided. Each mechanism is realized by a turning drive mechanism 5 shown in FIG.

  In the turning drive mechanism 5 shown in FIG. 1, the turning drive motor 11 is constituted by, for example, a stepping motor. A pulley 12a is attached to the rotating shaft 11a of the turning drive motor 11, a pulley 12b is attached to one end of the rotating shaft 13a of the first worm 13, and a rotation transmission belt is attached to each of the pulleys 12a-12b. (Timing belt) 12c is stretched, and the pulleys 12a, 12b and the timing belt 12c realize a rotation transmission mechanism of a drive source (motor).

  The worm wheel 14 is attached to the turning drive shaft 10 and meshed with a first worm 13 and a second worm 16 provided in parallel to each other and supported in a direction orthogonal to the turning drive shaft 10. is doing. The turning drive shaft 10 constitutes a turning drive shaft of a horizontal turning drive mechanism having a horizontal turning drive axis center L1 shown in FIG. 1 as an axis or a vertical turning drive mechanism having a vertical turning drive axis center L2 as an axis.

  The rotating shaft 16a of the second worm 16 is rotatably supported so as to be slidable within a predetermined movable range (s) in the axial direction. A pressing coil spring 17 having a predetermined elastic force is wound around one end side of the rotating shaft 16a, and the rotating coil 16a can be rotated through the rotation support member 18 in the direction of the arrow P by the pressing coil spring 17. Pressing.

  When the rotation of the first worm 13 is stopped, the pressing coil spring 17 presses the second worm 16 in the direction indicated by the arrow P by the elastic action of the coil spring, and the second worm 16 is pressed by the worm wheel 14. (The screw thread of the second worm 16 meshes with the tooth surface (b) of the worm wheel 14), and the worm wheel 14 is rotated in the directions indicated by the arrows Ea and Eb. Backlash prevention function that presses the surface (a) against the thread of the first worm 13 to absorb the play of the worm gear due to the combination of the first worm 13 and the worm wheel 14 and suppress the backlash of the gear. Is realized.

  A spur gear 15a is attached to the other end of the rotating shaft 13a of the first worm 13, and a spur gear 15b wider than the spur gear 15a is attached to the other end of the rotating shaft 16a of the second worm 16. The spur gears 15a and 15b mesh with each other to constitute a rotation transmission means for transmitting the rotation of the first worm 13 in the reverse direction to the second worm 16. The spur gears 15a and 15b may have a structure that maintains the meshing state even when the second worm 16 is slid in the axial direction. Here, the rotation transmission (reverse rotation) mechanism of the second worm 16 is configured by using two spur gears 15 a and 15 b, but depending on the distance between the first worm 13 and the second worm 16. For example, a structure using four spur gears or a structure driven by a belt may be used.

  The spur gears 15a, 15b, the second worm 16, the pressing coil spring 17, and the rotation support member 18 eliminate the backlash of the turning drive unit and provide an endless turnable worm gear drive unit (backlash prevention mechanism). Is realized.

  Here, the operation of the backlash prevention (backlash prevention) action at the time of turning stop of the turning drive mechanism that realizes the horizontal turning drive mechanism and the vertical turning drive mechanism of the turning camera system will be described.

  When the turning drive motor 11 is rotationally driven, the rotation of the turning drive motor 11 is transmitted to the first worm 13 by the pulleys 12a and 12b and the timing belt 12c via the rotation transmission mechanism of the drive source, and the first As the worm 13 rotates, the worm wheel 14 rotates at a predetermined gear ratio to drive the turning drive shaft 10 to rotate. As a result, the camera unit 3 rotates horizontally or vertically using the rotation drive shaft 10 as a rotation axis. During the turning drive, the rotation of the first worm 13 is transmitted to the rotating shaft 16a of the second worm 16 via the spur gears 15a and 15b, and the second worm 16 does not apply a load to the worm wheel 14. In the state, it rotates in the reverse direction with respect to the first worm 13.

  When the rotation of the turning drive motor 11 stops, the rotation of the first worm 13 stops and the rotation of the second worm 16 also stops. As the rotation stops, the second worm 16 is pressed in the direction of the arrow P by the elastic action of the pressing coil spring 17, and the rotation shaft 16a of the second worm 16 slides within the movable range (s). The screw thread of the second worm 16 meshes with the tooth surface (b) of the worm wheel 14 to rotate the worm wheel 14 in the directions indicated by the arrows Ea and Eb. As a result, the tooth surface (a) of the worm wheel 14 is pressed against the thread of the first worm 13 and the backlash of the worm gear due to the combination of the first worm 13 and the worm wheel 14 is prevented.

  As described above, when the rotation of the turning drive motor 11 stops, the rotation shaft 16a of the second worm 16 slides in the direction indicated by the arrow P due to the elastic action of the pressing coil spring 17, and thus the second worm. 16 rotates the worm wheel 14 in the directions indicated by the arrows Ea and Eb, and the tooth surface (a) of the worm wheel 14 is pressed against the screw thread of the first worm 13, so that the worm gear for turning drive (first The backlash of the worm 13 and the worm wheel 14) is prevented, thereby eliminating backlash of the turning drive unit, and the attitude (turning) control of the camera with high turning accuracy becomes possible. In addition, the backlash prevention mechanism according to the above embodiment is a double worm drive type backlash prevention mechanism using a worm by the second worm 16 meshing with the worm wheel 14 for turning drive, so that the high stop While realizing an accurate endless swivel worm gear drive, it is possible to provide a simple structure at low cost without the need for advanced and fine adjustment, and a stable and reliable swiveling operation can be expected over a long period of time.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

  DESCRIPTION OF SYMBOLS 1 ... Base part, 2 ... Turning drive part, 3 ... Camera unit part, 4 ... Camera (camera main body), 5 ... Turning drive mechanism, 11 ... Motor for turning drive, 12a, 12b ... Pulley, 12c ... Timing belt, DESCRIPTION OF SYMBOLS 13 ... 1st worm, 14 ... Worm wheel 14, 15a, 15b ... Spur gear, 16 ... 2nd worm, 17 ... Pressing coil spring, 18 ... Rotation support member.

Claims (4)

In a turning camera system comprising a surveillance camera and a turning drive mechanism for turning the camera,
The turning drive mechanism is
A motor for swivel drive;
A first worm for driving that is rotationally driven by the motor;
A worm wheel that meshes with the first worm and rotates the camera;
A second worm for preventing backlash that is provided parallel to the first worm and meshes with the worm wheel;
A rotation transmitting means for transmitting the rotation of the first worm to the second worm in the reverse direction;
A turning camera system comprising: a pressing unit that presses the second worm in an axial direction in mesh with the worm wheel when the rotation of the worm wheel is stopped.   The turning drive mechanism includes a horizontal turning drive mechanism for turning the monitoring camera in a left-right direction and a vertical turning drive mechanism for turning the monitoring camera in a vertical direction. The turning camera system according to claim 1.   The rotation transmission means includes a first spur gear pivotally attached to the first worm gear, and a second spur gear wider than the first spur gear pivotally attached to the second worm gear. The turning camera system according to claim 1, wherein the turning camera system is provided.   The turning camera system according to any one of claims 1 to 3, wherein the pressing means includes a pressing coil spring wound around a rotation shaft of the second worm gear.

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