JP2003315907A - Camera driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera driving device capable of controlling the direction of a camera main body with high accuracy by preventing the occurrence of a rotational phase shift due to a backlash with a simple and easy constitution. <P>SOLUTION: A camera driving unit 13 is provided with a pulley gear 26 to which the rotating force of a step motor 24 is transmitted, and a gear unit 28 which is engaged with the pulley gear 26 and rotated so as to change the photographing direction of a video camera 12. The gear unit 28 is constituted of 1st and 2nd gears 28a and 28b which are coaxially overlaid on top of each other and energized to rotate while interposing the teeth of the pulley gear 26 between their teeth. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a camera drive device that changes the direction of a camera body to change the shooting direction.

[0002]

2. Description of the Related Art As is well known, a video camera used, for example, for surveillance purposes is attached to a camera driving device in order to make its shooting direction variable by automatic or remote control.

This camera driving device is configured to change its direction by rotating the video camera in a predetermined direction by the rotational force of a motor transmitted through a rotational force transmission mechanism including gears. .

By the way, generally, the gears are engaged with each other with some play (backlash) in order to absorb a manufacturing precision and a diameter change due to temperature and to stably transmit a rotational force. Is designed.

Therefore, when the motor is rotated, a backlash between gears causes a rotational phase shift,
The rotational force of the motor will not be transmitted properly due to the turning of the video camera.

As a result, the amount of rotation of the motor and the amount of movement of the direction of the video camera cannot be accurately matched, and it becomes difficult to improve the resolution when moving the direction of the video camera. The problem arises.

[0007]

As described above, in the conventional camera driving device, since the rotational phase shift occurs due to the backlash between the gears, the orientation of the camera body can be controlled with high resolution and high accuracy. It has the problem of becoming difficult.

It is noted that, for example, Japanese Patent Laid-Open No. 11-30 has been used.
As shown in Japanese Patent No. 8520, various methods for correcting backlash have been developed, but none of them can be said to be suitable for practical use due to their complicated configurations and correction processes.

Therefore, the present invention has been made in consideration of the above circumstances, and it is possible to control the orientation of the camera body with high accuracy by preventing the occurrence of a rotational phase shift due to backlash with a simple structure. It is an object of the present invention to provide a very good camera driving device.

[0010]

SUMMARY OF THE INVENTION A camera drive device according to the present invention includes a drive side gear and a driven gear which is meshed with the drive side gear and rotated to change the photographing direction of the camera body. It is intended for those equipped with side gears. A driven gear and a first gear and a second gear which are coaxially overlapped with each other and are meshed with the drive gear, respectively.
With respect to the first and second gears, the teeth of the first gear and the second gear
And a biasing means for applying a rotation biasing force so as to sandwich the tooth of the drive side gear with the tooth of the gear of the above.

According to the above-mentioned structure, the driven gears are superposed coaxially, and the first and second gears are urged to rotate so that the teeth of the driving gear are sandwiched by their teeth. Since it is configured, it is possible to control the orientation of the camera body with high accuracy by preventing the occurrence of rotational phase shift due to backlash with a simple configuration.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows an outline of the surveillance camera system described in this embodiment. For example, when the monitored area is indoors, its top plate 1
1, a camera drive unit 13 equipped with a video camera 12 is suspended.

The camera drive unit 13 is covered with a dome case 14 attached to the top plate 11,
It is designed so that it cannot be seen from the outside. However, the video camera 12 can pass through the dome case 14 and shoot an external subject.

Here, the camera drive unit 13 is
It is controlled by the control unit 15. The control unit 15 receives operation information from the outside and rotates the video camera 12 in the horizontal (pan) direction and the vertical (tilt) direction with respect to the camera drive unit 13 to change the shooting direction. To control.

Further, the control unit 15 receives the operation information from the outside, and performs various controls necessary for photographing such as the photographing start and stop instructions and the zoom adjustment to the video camera 12. To do. Further, the control unit 15 operates so as to supply the image information captured by the video camera 12 to the monitor 16 for viewing and listening and the recording / reproducing by the recording / reproducing device 17.

FIG. 2 shows the appearance of a camera drive unit 13 equipped with the video camera 12. 3A, 3B, and 3C show the camera drive unit 13 viewed from the top, side, and front, respectively. That is, reference numeral 18 is a mounting board, which is the top board 11
Is attached to.

An axial bearing 19 attached to the central portion of the mounting substrate 18 allows the mounting substrate 18 to be rotatable about an axis (Y-axis) in the hanging direction with respect to the top plate 11, that is, horizontally. The rotary base 20 is supported so as to be rotatable in any direction.

A tilt bearing 21 is provided on the rotary base 20 so that an axis (X
The camera holder 22 is supported so as to be rotatable about its axis, that is, to be rotatable in the vertical direction. The video camera 12 is attached to the camera holder 22. Therefore, the video camera 1
2 can rotate independently in the horizontal and vertical directions.

A motor mounting pan 23 is attached to the rotary base 20. A step motor 24 is attached to the motor mounting pan 23. A motor pulley 25 is fitted on the rotary shaft 24 a of the step motor 24.

A pulley gear 26 is rotatably supported on the motor mounting pan 23. The pulley gear 26 includes a gear 26a having a predetermined diameter and the gear 2
A gear 26b having a smaller diameter than 6a is integrally formed so as to be coaxial with the gear 26a. The gear 26a and the motor pulley 25 are connected by a belt 27 so as to be able to transmit a rotational force.

Further, the gear 26b having a small diameter of the pulley gear 26 is mounted on the mounting substrate 18 by the shaft bearing 19 thereof.
Is engaged with a gear unit 28 fixed so as to be coaxial with the rotation axis (Y axis) of the rotation base 20.

Therefore, when the step motor 24 is driven to rotate, the rotational force of the rotary shaft 24a of the step motor 24 causes the motor pulley 25, the belt 27, and the gear 2 of the pulley gear 26 to rotate.
It is transmitted to the gear unit 28 via 6a and the gear 26b.

In this case, the driven gear unit 28
Is fixed to the mounting substrate 18, the pulley gear 26 on the drive side revolves around the gear unit 28 while rotating. As a result, the rotary substrate 20 becomes Y
The video camera 12 is rotated about the axis and is rotated in the horizontal direction.

A motor mounting tilt 29 is attached to the rotary substrate 20. A step motor 30 is attached to the motor mounting tilt 29. A motor pulley 31 is fitted on the rotary shaft 30a of the step motor 30.

A pulley gear 32 is rotatably supported on the motor mounting tilt 29. The pulley gear 32 is formed by integrally forming a gear 32a having a predetermined diameter and a gear 32b having a smaller diameter than the gear 32a so as to be coaxial with each other. The belt 33 is connected to the belt 33 so that the rotational force can be transmitted.

Further, the small diameter gear 32b of the pulley gear 32 is coaxial with the axis of the tilt bearing 21 of the camera holder 22, that is, the rotation axis (X axis) of the camera holder 22 with respect to the rotary base 20. It is meshed with the fan gear unit 34 fixed so as to face up.

Therefore, when the step motor 30 is rotationally driven, the rotational force of the rotary shaft 30a causes the motor pulley 31, the belt 33, and the gear 3 of the pulley gear 32 to rotate.
It is transmitted to the fan gear unit 34 via 2a and the gear 32b.

In this case, since the fan-shaped gear unit 34 on the driven side is fixed to the camera holder 22, the camera holder 2 is driven by the rotational force of the pulley gear 32 on the driving side.
2 is rotated about the X axis, and the video camera 12 is rotated vertically.

4 and 5 show details of the gear unit 28. The gear unit 29 has a configuration in which a first gear 28a and a second gear 28b having the same diameter and the same number of teeth are coaxially overlapped with each other.

That is, a plurality (three in the illustrated case) of elastic engaging pieces 2 projectingly provided on one plane of the first gear 28a.
By engaging 8c with an engaging portion 28d formed on the second gear 28b, the first and second gears 28a, 2
8b is united.

In this case, the first and second gears 28a, 28a
Between 8b, some play is set so as to be mutually rotatable. Then, a coil-shaped spring 28g as an urging means is engaged between the locking portion 28e formed on the first gear 28a and the locking portion 28f formed on the second gear 28b. Therefore, the first gear 28a
On the other hand, the second gear 28b is rotationally biased in the direction indicated by the arrow A in FIG.

However, the rotation of the second gear 28b with respect to the first gear 28a by the urging force of the spring 28g prevents the stopper 28h formed on the second gear 28b from rotating.
Until it comes into contact with the locking portion 28i formed on the first gear 28a.

FIG. 6 shows the meshing state of the above-mentioned gear unit 28 and the gear 26b of the pulley gear 26. In FIG. 6, the solid line indicates the first gear 28a and the broken line indicates the second gear 28b. In this case, paying attention to one tooth 26b1 of the gear 26b, the tooth 26b1 is sandwiched between the tooth of the first gear 28a and the tooth of the second gear 28b by the biasing force of the spring 28g. 26
b and rattling of gear unit 28 (backlash)
It will be meshed without teeth.

Therefore, whether the gear 26b is rotated in the clockwise direction or the counterclockwise direction in FIG. 6, its rotational force is immediately transmitted to the gear unit 28, and the gear unit 28 is rotated relative to the gear 26b. It is driven to rotate without delaying the phase. As a result, the orientation of the video camera 12 can be controlled with high accuracy.

FIG. 7 shows a drive side gear 35 and a driven side gear 36.
It shows backlash when and are meshed.
Backlash occurs because it is necessary to separate the pitch distances in advance in order to absorb the precision of the molded parts, the increase in the diameter of the gear due to the temperature, etc., especially in the case of resin-molded gears. For example, if the design is made so that there is no backlash, problems such as tooth bottom contact will occur, resulting in an increase in rotational load.

However, because of this backlash, even if the drive-side gear 35 rotates, the driven-side gear 36 does not rotate due to the backlash, and a rotational phase shift occurs there. It becomes impossible to accurately control the direction of.

Usually, the backlash has a backlash of about 0.2 mm, and when the pitch radius is 35 mm, a dead state of 0.33 degree occurs at the rotation angle. In other words, it cannot have a resolution of 0.33 degrees or more.

For example, if the rotation accuracy of the motor is 200 steps and the reduction ratio by the gear is 40, then 360 / (20
It is possible to have a rotation accuracy of 0 × 40) = 0.045 degrees, but backlash will cause it to stay at 0.33 degrees.

On the other hand, according to the above-described embodiment, since the backlash does not occur, it is possible to maintain the resolution of the movement of the video camera 12 in the direction of rotation of 0.045 degrees. Becomes

Incidentally, the countermeasure for preventing the occurrence of the rotational phase shift due to the backlash is not limited to the gear unit 28 for rotating the video camera 12 in the horizontal direction, but the video camera 12 can be moved in the vertical direction. It can also be applied to the fan gear unit 34 for rotating.

FIG. 8 shows the details of the fan gear unit 34. The fan gear unit 34 includes a first fan gear 34a and a second fan gear 34 having the same diameter and the same number of teeth.
It has a structure in which b and b are superposed coaxially.

In this case, the first and second fan gears 34
A small amount of play is set between a and 34b so that they can rotate relative to each other. Then, one end is locked by the locking portion 34c formed on the first fan gear 34a, the central portion is wound around the rotating shaft 34d of the first fan gear 34a, and the other end is With respect to the first fan gear 34a, the torsion spring 34f as an urging means is engaged with the engaging portion 34e formed on the second fan gear 34b.
The second fan gear 34b is urged to rotate in the direction indicated by arrow B.

However, this torsion spring 34f
When the second fan gear 34b is rotated with respect to the first fan gear 34a by the biasing force of the second fan gear 34a, the locking portion 34e formed on the second fan gear 34b is locked by the lock formed on the first fan gear 34a. The contact is made with the portion 34g.

By using the fan gear unit 34 having the structure as shown in FIG. 8, even when the video camera 12 is rotated in the vertical direction, the direction can be controlled with high accuracy.

The present invention is not limited to the above-described embodiments, but can be variously modified and implemented without departing from the scope of the invention.

[0046]

As described above in detail, according to the present invention,
It is possible to provide a very good camera drive device that can prevent the occurrence of a rotational phase shift due to backlash with a simple structure and can control the orientation of the camera body with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, which is shown to explain an outline of a surveillance camera system.

FIG. 2 is a perspective view shown for explaining the external appearance of a camera drive unit equipped with the video camera according to the embodiment.

FIG. 3 is a diagram showing a camera drive unit equipped with the video camera according to the embodiment, as viewed from the top, side, and front.

FIG. 4 is an exploded perspective view for explaining a detailed structure of the gear unit according to the same embodiment.

FIG. 5 is a diagram shown for explaining a detailed structure of the gear unit according to the embodiment.

FIG. 6 is a diagram shown for explaining a meshing state of the gear unit in the same embodiment.

FIG. 7 is a view for explaining backlash of gears.

FIG. 8 is an exploded perspective view for explaining the detailed structure of the fan gear unit in the same embodiment.

[Explanation of symbols]

11 ... top plate, 12 ... video camera, 13 ... Camera drive unit, 14 ... Dome case, 15 ... Control unit, 16 ... Monitor, 17 ... Recording / reproducing device, 18 ... Mounting board, 19 ... Axial bearing, 20 ... rotating base, 21 ... Tilt bearing, 22 ... Camera holder, 23 ... Motor mounting pan, 24 ... Step motor, 25 ... motor pulley, 26 ... pulley gear, 27 ... Belt, 28 ... gear unit, 29 ... Tilt for motor mounting, 30 ... Step motor, 31 ... motor pulley, 32 ... pulley gear, 33 ... Belt, 34 ... fan gear unit, 35 ... drive side gear, 36 ... Driven side gear.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 17/00 G03B 17/00 B H04N 5/222 H04N 5/222 BF term (reference) 2H105 AA03 AA06 AA12 AA17 AA26 AA27 EE35 3J009 DA03 DA06 EA04 EA11 EA21 EA42 EB13 EB17 EC03 ED14 FA23 5C022 AA01 AB62 AC27

Claims (6)

[Claims] 1. A camera drive device comprising: a drive-side gear; and a driven-side gear that is engaged with the drive-side gear to rotate to change the shooting direction of the camera body. First and second gears having side gears coaxially overlapped with each other and meshed with the drive side gears; and teeth of the first gear and the first gears with respect to the first and second gears. A camera driving device, comprising: a tooth of the second gear and an urging unit that applies a rotational urging force so as to sandwich the tooth of the drive-side gear. 2. The camera driving device according to claim 1, wherein the driven gear is used to move a photographing direction of the camera body in a horizontal direction. 3. The camera drive device according to claim 1, wherein the driven gear is used to move a shooting direction of the camera body in a vertical direction. 4. The driven gear has a plurality of elastic engagement pieces projectingly provided on one plane of the first gear engaged with an engagement portion formed on the second gear. 2. The camera drive device according to claim 1, wherein the first and second gears are combined together. 5. The spring means engages a spring with an engaging portion formed on the first gear and an engaging portion formed on the second gear. The camera drive device according to claim 1. 6. A camera drive device in which a photographing direction of a camera body is varied via a rotational force transmission mechanism by gears, wherein one gear of two gears meshed with each other is coaxially overlapped with each other. A camera drive device comprising a first gear and a second gear to which a rotational biasing force is applied.