Patent Description:
As imaging devices for panning and tilting camera units, video cameras used for shooting in small studios and live broadcasts are known. These cameras need to use large and heavy lens barrels to obtain high-quality images and require large driving forces. Further, in order to enable image expression with smooth camera work, smooth rotational drive in a wide speed range from a low speed to a high speed is required.

<CIT> describes a configuration that employs a timing belt and a pulley as a rotational drive mechanism for panning and tilting in order to enable smooth rotational drive. According to <CIT>, since the timing belt can remove the backlash of the drive mechanism, the rattling when the camera is panned or tilted is reduced, and smooth rotational drive is enabled. However, since the timing belt is an elastic member, there is a problem that the image shakes due to the bending and expansion/contraction of the belt when a large lens barrel is driven or stopped at high acceleration.

On the other hand, <CIT> describes a technique of a so-called "scissors gear" in which one of a pair of spur gears meshing with each other as the rotational drive mechanism is divided into two in a thickness direction and one of two divided gears is biased in a circumferential direction around a rotation axis by a spring or the like. In the scissors gear configuration, backlash can be removed and rattling during rotational drive can be suppressed.

<FIG> shows an example of a structure that uses a conventional scissors gear as a panning and tilting drive mechanism of the camera unit. As shown in <FIG>, in the scissors gear configuration using the conventional spur gear, a first spur gear <NUM> is fixed to a tilting shaft <NUM> or a panning shaft (not shown) and meshes with a gear portion of a geared pulley <NUM> to transmit a driving force of a motor <NUM>.

Here, a second spur gear <NUM> is biased in a circumferential direction around a rotation axis by a biasing member such as a coil spring <NUM>. Accordingly, the teeth of the gear portion of the geared pulley <NUM> are sandwiched by the teeth of the first spur gear <NUM> and the teeth of the second spur gear <NUM>, so that backlash can be removed.

However, in the related art disclosed in <CIT>, since the gear portion is always in strong contact with the gears on the other side due to the scissors gear biasing structure, there is concern that the unevenness in transmission torque becomes large due to the rotation phase of the gear. In particular, when the camera is panned or tilted at a low speed, unevenness in speed may occur and the image may shake.

In order to reduce the unevenness in transmission torque, it is necessary to weaken the biasing force of the spring or the like of the scissors gear. However, since a large torque is applied due to inertia when the large lens barrel is suddenly stopped from the high-speed rotation state, the torque causes the lens barrel to vibrate and causes the image to shake if the biasing force is weak.

That is, the scissors gear configuration with the spur gears has a problem as below. When the biasing force is large, the speed becomes uneven particularly at the low-speed drive state. On the other hand, when the biasing force is small, the torque generated by the inertia of the lens barrel cannot be maintained and the lens barrel shakes.

For example, in the example of the configuration shown in <FIG>, when the biasing force to the second spur gear <NUM> is weak, a torque generated by the inertia of a camera unit <NUM> at the time of rapidly tilting or panning and suddenly stopping the camera unit <NUM> exceeds the force of the coil spring <NUM>. As a result, the camera unit <NUM> vibrates.

On the other hand, when the biasing force to the second spur gear <NUM> is strong, it is possible to suppress the vibration of the camera unit at the time of tilting or panning at a high speed or sudden stopping of the camera unit. However, the teeth of the first spur gear <NUM> and the second spur gear <NUM> strongly come into contact with the teeth of the gear portion of the geared pulley <NUM> and large unevenness in the transmission torque occurs due to the rotation phase of the gear.

Regarding such a problem, for example, even in the control of rotating the camera unit <NUM> at a certain constant speed in the tilting or panning direction, the rotational speed becomes uneven due to the uneven torque, which causes the captured image to be blurred.

<FIG> is an example that plots the panning speed of the camera unit <NUM> if the biasing force to the second spur gear <NUM> is weak. Although the speed of the trapezoidal wave is input, it can be seen that the vibration is generated at the time of starting and stopping by looking at the actual panning speed since the force of the coil spring <NUM> is weak. Further, <FIG> is an example that plots the panning speed of the camera unit <NUM> if the biasing force to the second spur gear <NUM> is strong. In this case, it can be seen that the vibration at the time of starting and stopping can be suppressed, but the speed is not kept constant due to the unevenness of the transmission torque.

Prior art document <CIT> discloses a camera driving unit that is provided with a pulley gear to which the rotating force of a step motor is transmitted, and a gear unit which is engaged with the pulley gear and rotated so as to change the photographing direction of a video camera. The gear unit is constituted of gears which are coaxially overlaid on top of each other and energized to rotate while interposing the teeth of the pulley gear between their teeth.

Prior art document <CIT> discloses a method to manufacture a resin sealed type electronic part. After molded articles consisting of phenol resin, epoxy resin and the like, have been formed in one body by adhering them on the upper and lower surfaces of a metal lead frame through the intermediaries of the binding material layers consisting of phenol resin, epoxy resin and the like, a resin sealed type electron part is obtained by sealing the element using a casting material consisting of phenol resin, epoxy resin and the like after the element has been die-inner bonded on the molded article. Each one of the molded articles is adhered to the upper and lower surfaces of the lead frame.

An object of the one of inventions is to provide a pan or tilt head and the like capable of reducing rattling and vibration when a rotation is suddenly changed while reducing the unevenness in rotational speed for smooth rotational drive.

The above-described object is solved by a pan or tilt head having the features of claim <NUM>. An imaging device is stated in claim <NUM>. Further developments are stated in the dependent claims.

Further features of the one or more embodiments of the claimed invention will become apparent from the following description of embodiments with reference to the attached drawings.

Hereinafter, with reference to the accompanying drawings, favorable mode of the present invention will be described using Embodiments. In each diagram, the same reference signs are applied to the same members or elements, and duplicate description will be omitted or simplified.

Further, in the embodiment, an example in which a network camera used for live streaming or the like as an imaging device is combined with a pan or tilt head for panning and tilting will be described. However, the imaging device includes an electronic device such as a digital still camera, a digital movie camera, a smartphone with a camera, a tablet computer with a camera, and an in-vehicle camera having an imaging function.

<FIG> is a perspective view showing a video camera <NUM> of the embodiment of the present invention.

As shown in <FIG>, a video camera (network camera) <NUM> as the imaging device of the embodiment includes a camera unit <NUM>, a panning unit <NUM>, and a base portion <NUM>.

The video camera <NUM> shown in <FIG> is installed, for example, on a ceiling of a live house or a shooting studio as a fixed surface and the camera unit <NUM> can be rotated in the panning direction and the tilting direction. By panning and tilting the camera unit <NUM> toward a subject, it is possible to shoot videos for video production and live streaming. Further, the video camera <NUM> can be not only installed on the ceiling but also placed on a horizontal surface to capture an image.

When the camera unit <NUM> is panned and tilted, it is possible to capture an image without blurring by smoothly driving the camera unit <NUM> without any unevenness in rotational speed. Further, the camera unit <NUM> can perform panning and tilting operations in a wide speed range from a high speed range to a low speed range. Therefore, even a subject moving at an uneven speed can be photographed by allowing the camera unit <NUM> to follow the subject.

In this way, the video camera <NUM> can rotate the camera unit <NUM> in the panning and tilting directions. Here, the panning unit <NUM> and the base portion <NUM> constitute a pan or tilt head for rotating the camera unit <NUM> in the panning and tilting directions. Additionally, in the embodiment, the camera unit <NUM> is attached to the pan or tilt head and cannot be attached or detached by the user. However, the camera unit <NUM> may be simply attached to or detached from the pan or tilt head.

Next, a tilting drive mechanism <NUM> of the video camera <NUM> will be described. The tilting drive mechanism <NUM> is disposed in the panning unit <NUM>.

<FIG> is a perspective view showing the tilting drive mechanism <NUM> of the video camera <NUM>. Additionally, the tilting drive mechanism (tilting drive unit) functions as a rotational drive unit for rotating the camera unit <NUM> in a predetermined tilting direction. Further, in the embodiment, a configuration in which both the rotation in the panning direction and the rotation in the tilting direction are possible will be described, but only the rotation in one direction may be possible.

As shown in <FIG>, a lens barrel <NUM> in the camera unit <NUM> is supported by a lens barrel support member <NUM> and the lens barrel support member <NUM> includes a tilting shaft <NUM>. The lens barrel support member <NUM> is tiltably supported by a pan base <NUM> in the panning unit <NUM>.

Here, the rotation of the camera unit <NUM> in the tilting direction is performed by the tilting drive mechanism <NUM>. The tilting drive mechanism <NUM> includes a tilting motor <NUM> which is a drive source, a rubber <NUM>, a timing belt <NUM>, a geared pulley <NUM>, a first helical gear <NUM>, a second helical gear <NUM>, and the like. Further, the geared pulley <NUM> includes a pulley portion 23B and a gear portion 23A and the gear portion 23A is a helical gear. Here, the first helical gear <NUM> and the second helical gear <NUM> respectively function as a first gear and a second gear which rotate around a predetermined rotation axis in the predetermined direction and are coaxial with the predetermined rotation axis. Further, the gear portion 23A functions as a third gear which transmits a driving force from the drive source.

The tilting motor <NUM> is attached to the panning unit <NUM> through the rubber <NUM> and the geared pulley <NUM> is rotatably supported by the panning unit <NUM>. The tilting motor <NUM> and the pulley portion 23B of the geared pulley <NUM> are connected by the timing belt <NUM>. The first helical gear <NUM> is fixed so that the center substantially coincides with the tilting shaft <NUM> and is disposed to mesh with the gear portion 23A of the geared pulley <NUM>.

Thus, when the tilting motor <NUM> is driven, the geared pulley <NUM> rotates through the timing belt <NUM> and further the rotation is transmitted to the first helical gear <NUM> meshing with the gear portion 23A of the geared pulley <NUM>, so that the camera unit <NUM> can be tilted.

Next, a configuration for removing the backlash of the first helical gear <NUM> of the tilting drive mechanism <NUM> will be described with reference to <FIG>.

<FIG> is an exploded perspective view showing the helical gears <NUM> and <NUM>.

As shown in <FIG>, the second helical gear <NUM> is disposed not to be rotatable with respect to the first helical gear <NUM> and to be movable in parallel to the rotation axis direction. Further, the second helical gear <NUM> is fixed to the first helical gear <NUM> through a coil spring <NUM> and a spring retainer <NUM> and is always biased in the rotation axis direction to approach the first helical gear <NUM>. Furthermore, the plurality of coil springs <NUM> may be elastic members and function as biasing units.

When the first helical gear <NUM> meshes with the gear portion 23A of the geared pulley <NUM>, backlash is generated. However, it is possible to remove the backlash as shown in <FIG> by biasing the second helical gear <NUM> with the coil spring <NUM>.

The configuration for removing this backlash is such that the teeth of the gear portion 23A of the geared pulley <NUM> are sandwiched between the teeth of the first helical gear <NUM> and the second helical gear <NUM> and has a so-called scissors gear configuration. With this configuration, when the camera unit <NUM> is rotated in the tilting direction, rattling due to backlash is removed and smooth operation is enabled.

When the camera unit <NUM> is rapidly tilted and suddenly stopped, a torque is applied to the second helical gear <NUM> due to the inertia of the camera unit <NUM>. The force generated in one tooth of the second helical gear <NUM> by this torque is indicated by F1 of <FIG>.

<FIG> is a schematic view showing the meshing of the helical gears <NUM> and <NUM>.

Assuming that the helix angle of the second helical gear <NUM> is θ, F1 can be divided into F1cosθ which is a force in the direction perpendicular to the tooth surface and F1sinθ which is a force in the direction in contact with the tooth surface.

When the second helical gear <NUM> slips and moves in the axial direction due to F1sinθ, the configuration for removing backlash cannot be established. Therefore, a configuration that can always remove backlash is maintained by setting the biasing force F2 by the coil spring <NUM> to a large value and suppressing slippage due to F1sinθ.

Since F1sinθ becomes a small value when the helix angle θ is set to a small value (in the embodiment, θ=<NUM>°) of <NUM>° or less, the backlash can be always removed even when the biasing force F2 due to the coil spring <NUM> is set to be small. Further, it is possible to prevent the second helical gear <NUM> and the gear portion 23A of the geared pulley <NUM> from hitting strongly by reducing the biasing force F2. Accordingly, the unevenness of the transmission torque due to the rotation phase of the gear can be reduced and the camera unit <NUM> can be smoothly tilted.

So far, the configuration for removing the backlash of the first helical gear <NUM> has been described. By biasing the second helical gear <NUM> in the thrust direction, the backlash can be removed by sandwiching the teeth of the gear portion 23A of the geared pulley <NUM>. Next, the configuration for biasing the second helical gear <NUM> will be described in detail.

As shown in <FIG>, the first helical gear <NUM> includes three arc-shaped ribs 24A having the same radius of the arc-shaped portion and the arc-shaped ribs 24A are arranged along the circumference around the rotation axis so that the center of the arc substantially coincides with the rotation axis. Further, the inner diameter of the second helical gear <NUM> is disposed to be fitted to the outer peripheral portion of the arc-shaped rib 24A.

Since there is a slight backlash in the fitting of the inner diameter of the second helical gear <NUM>, the second helical gear <NUM> may be slightly diagonally tilted due to the backlash.

However, since the outer diameter of the arc-shaped rib 24A is larger than the outer diameter of the tilting shaft <NUM>, the inclination of the second helical gear <NUM> can be suppressed to be small compared to the case in which the second helical gear <NUM> is directly fitted to the outer diameter of the tilting shaft <NUM>. Further, the coil springs <NUM> are arranged alternately with the arc-shaped ribs 24A.

With this configuration, it is possible to apply a biasing force to the vicinity of the outer periphery while maintaining a large fitting diameter of the second helical gear <NUM>. The inclination of the second helical gear <NUM> due to the variation in the biasing force can be suppressed to be small by applying the biasing force to the vicinity of the outer periphery.

Next, the attachment shape of the tilting motor <NUM> in the tilting drive mechanism <NUM> will be described with reference to <FIG>. The tilting motor <NUM> is attached to a support metal plate <NUM> through the rubber <NUM> and the support metal plate <NUM> is attached to the pan base <NUM>. Further, the driving force of the tilting motor <NUM> can be transmitted to the geared pulley <NUM> by the timing belt <NUM>.

Since both the rubber <NUM> and the timing belt <NUM> are members having low rigidity, the vibration of the tilting motor <NUM> is less likely to be transmitted to the pan base <NUM> or the geared pulley <NUM>. Accordingly, it is possible to prevent the image being captured from shaking due to the vibration of the tilting motor <NUM>.

Next, the panning drive mechanism <NUM> of the video camera <NUM> will be described. The panning drive mechanism (panning drive unit) <NUM> functions as a rotational drive unit which rotates the camera unit <NUM> in a predetermined panning direction.

<FIG> is a perspective view showing the panning drive mechanism <NUM> of the video camera <NUM>. As shown in <FIG>, the pan base <NUM> includes a panning shaft <NUM> and is supported by the base portion <NUM> to be pan-rotatable.

The rotation of the camera unit <NUM> in the panning direction is performed by the panning drive mechanism <NUM>. As shown in <FIG>, the panning drive mechanism <NUM> includes a pan motor <NUM>, a rubber <NUM>, a timing belt <NUM>, a geared pulley <NUM>, a first helical gear <NUM>, a second helical gear <NUM>, and the like. Further, the geared pulley <NUM> includes a pulley portion 33B and a gear portion 33A and the gear portion 33A is a helical gear.

The pan motor <NUM> is attached to the base portion <NUM> through the rubber <NUM> and the geared pulley <NUM> is rotatably supported by the base portion. The pan motor <NUM> and the pulley portion 33B of the geared pulley <NUM> are connected by the timing belt <NUM>. The first helical gear <NUM> is fixed so that the center substantially coincides with the panning shaft <NUM> and is disposed to mesh with the gear portion 33A of the geared pulley <NUM>.

Thus, when the pan motor <NUM> is driven, the geared pulley <NUM> rotates through the timing belt <NUM> and further the rotation is transmitted to the first helical gear <NUM> meshing with the gear portion 33A of the geared pulley <NUM>. Then, the pan base <NUM> can be panned and hence the camera unit <NUM> can be panned.

The second helical gear <NUM> is disposed not to be rotatable with respect to the first helical gear <NUM> and to be movable in parallel to the rotation axis direction. As shown in <FIG>, the second helical gear <NUM> is fixed to the first helical gear <NUM> through the coil spring <NUM> and the spring retainer <NUM> and is always biased in the direction to approach the first helical gear <NUM>. The pan motor <NUM> is attached to the support metal plate <NUM> through the rubber <NUM> and the support metal plate <NUM> is attached to the base portion <NUM>.

These configurations are the same as those of the tilting drive mechanism <NUM> and the panning can be smoothly performed by removing backlash.

<FIG> is a graph plotting the panning speed characteristics of the video camera <NUM>.

Vibration is not generated by reducing backlash even in the sudden acceleration or stop and a smooth rotation with little unevenness in speed is allowed even in the rotation at a constant speed.

In the embodiment, the camera unit <NUM> is rotatable in the tilting direction and the panning direction, but may be rotatable in any one of the tilting direction and the panning direction.

Further, in the embodiment, the tilting drive mechanism <NUM> and the panning drive mechanism <NUM> are decelerated in two stages, but may be deceleration mechanisms having three or more stages.

Claim 1:
A pan or tilt head (<NUM>, <NUM>) comprising:
a drive unit (<NUM>, <NUM>) which rotates a camera unit (<NUM>) in a predetermined direction;
first and second gears (<NUM>, <NUM>) which rotate around a predetermined rotation axis in the predetermined direction and are coaxial with the predetermined rotation axis, wherein the second gear (<NUM>) is disposed not to be rotatable with respect to the first gear (<NUM>);
a third gear (23A) which meshes with the first and second gears (<NUM>, <NUM>) and transmits a driving force from the drive unit (<NUM>, <NUM>); and
a biasing unit (<NUM>) which biases the second gear (<NUM>) in the rotation axis direction,
wherein the first gear (<NUM>), the second gear (<NUM>), and the third gear (23A) include helical gears, and
wherein the second gear (<NUM>) is disposed to be movable in the rotation axis direction with respect to the first gear (<NUM>).