JP5661892B2 - Dome camera - Google Patents

Description

  The present invention relates to a dome type camera provided with a dome cover that covers a camera lens.

  Dome cameras are used for surveillance cameras and the like. In the surveillance camera, the camera lens is covered with a dome cover, and the camera lens is protected by the dome cover. A general surveillance camera has a pan / tilt function (function of rotating a camera lens in the pan direction and the tilt direction) and a zoom function.

  The conventional dome type camera includes a hemispherical dome cover, and is arranged so that the rotation center of the camera lens is on the optical axis and coincides with the center of the dome cover. It has been known that a good image can be obtained by such an arrangement.

  However, with the arrangement of the camera lens as described above, vignetting occurs when photographing in a direction with a large tilt angle (a direction close to the horizontal direction), and a good image cannot be obtained. Therefore, conventionally, a technique for offsetting the camera lens in the zenith direction from the center of the dome cover has been proposed (see, for example, Patent Documents 1 and 2).

  By offsetting the camera lens in the zenith direction of the dome cover, it is possible to photograph a direction with a large tilt angle (a direction close to the horizontal direction) without causing vignetting.

Japanese Patent Laying-Open No. 2005-300659 JP 2005-221737 A

  However, in the conventional dome type camera, since the camera lens is offset from the center of the dome cover, an aberration caused by the lens effect of the dome cover is generated, and the image quality is deteriorated due to the aberration. In other words, when shooting in a direction with a large tilt angle (a direction close to the horizontal direction), ensuring a wide field of view and reducing image quality degradation are in a trade-off relationship, and it has been extremely difficult to achieve both. .

  The present invention has been made in order to solve the above-described conventional problems, and achieves both wide field of view and reduction in image quality degradation when photographing in a direction with a large tilt angle (a direction close to the horizontal direction). An object of the present invention is to provide a dome-type camera that can be used.

  The dome type camera of the present invention includes a camera lens that can be rotated in a tilt direction, a dome cover that covers the camera lens, and a tilt rotation axis of the camera lens that is located in a zenith direction from a center position of the dome cover. And a filter insertion means for inserting a polarization filter or a partial light shielding filter on the optical axis of the camera lens in response to the tilt angle of the camera lens becoming larger than a predetermined threshold angle. doing.

  With this configuration, when the tilt angle of the camera lens increases, a polarizing filter or a partial light blocking filter (a light blocking filter that blocks a part of incident light) is inserted on the optical axis of the camera lens. By using the polarizing filter and the partial light blocking filter, it is possible to suppress the deterioration of the image quality due to the offset of the camera lens. As a result, when photographing in a direction with a large tilt angle (a direction close to the horizontal direction), it is possible to achieve both a wide field of view and a reduction in image quality degradation.

  Further, in the dome type camera of the present invention, the partial light shielding filter has a light shielding area that shields half of the field of view of the camera lens, and the light shielding area is a half range opposite to the zenith direction of the dome cover. It has the structure set to.

  With this configuration, when shooting in a direction with a large tilt angle (a direction close to the horizontal direction), the light shielding area of the partial light shielding filter causes the opposite side to the zenith direction of the dome cover (the side with the large tilt angle and the side close to the horizontal direction). ) Is shaded. This light-shielded range is considered to correspond to a portion that does not have a very high molding accuracy of the dome cover and causes image quality degradation. By shielding this portion, image quality deterioration can be suppressed.

  In the dome-type camera of the present invention, the camera lens has a zoom function, and the filter insertion means has a zoom range of the camera lens within a magnification range on the TELE end side that is larger than a predetermined threshold magnification. In this case, the polarizing filter or the partial light shielding filter is inserted on the optical axis of the camera lens.

  With this configuration, when the zoom magnification of the camera lens is set to the TELE end side, a polarizing filter or a partial light shielding filter is inserted on the optical axis of the camera lens, and the offset of the camera lens is obtained by the polarizing filter or the partial light shielding filter. Can suppress degradation of image quality. Note that when the zoom magnification of the camera lens is set to the WIDE end side, there is little deterioration in image quality. Good.

  In the dome type camera of the present invention, the polarizing filter or the partial light shielding filter is configured to be inserted in front of the camera lens.

  With this configuration, the polarizing filter and the partial light shielding filter are inserted on the front side of the camera lens, and the light before entering the camera lens is partially shielded by the polarizing lens by the polarized light or the partial light shielding filter. That is, the light polarized by the polarizing lens or the light partially blocked by the partial light blocking filter enters the camera lens. Thereby, it is possible to suppress the deterioration of the image quality due to the offset of the camera lens.

  In the dome type camera of the present invention, the polarizing filter is configured to be inserted on the front side of the image pickup device using an infrared cut filter and optical glass switching means.

  With this configuration, the polarizing filter can be inserted using the switching means between the infrared cut filter and the optical glass. By using the existing mechanism (infrared cut filter and optical glass switching means), the number of parts can be reduced, the manufacturing cost can be reduced, and the size can be reduced compared with the case where a dedicated mechanism is provided separately. Is possible.

  The present invention provides a dome-type camera having an effect of ensuring both a wide field of view and a reduction in image quality degradation when photographing in a direction with a large tilt angle (a direction close to the horizontal direction). It can be done.

Explanatory drawing of the dome type camera (tilt angle: large) in 1st Embodiment Explanatory drawing of the dome type camera (tilt angle: small) in 1st Embodiment The perspective view of the lens unit (polarization filter: insertion position) in a 1st embodiment The perspective view of the lens unit (polarization filter: retraction position) in a 1st embodiment The perspective view of the lens unit (light-shielding filter: insertion position) in the modification of 1st Embodiment Relationship diagram between tilt angle, offset amount, and presence / absence of filter insertion in the first exemplary embodiment Relationship diagram between zoom magnification and presence / absence of filter insertion in the first embodiment Relationship diagram between zoom magnification and presence / absence of filter insertion in a modification of the first embodiment Explanatory drawing of the filter insertion area | region in 1st Embodiment The perspective view of the camera unit in 2nd Embodiment Front view of camera unit (polarization filter insertion position) in the second embodiment Front view of camera unit (infrared cut filter insertion position) in the second embodiment Front view of camera unit (optical glass insertion position) in the second embodiment The perspective view of the filter switching mechanism in the modification of 2nd Embodiment The perspective view of the filter switching mechanism (at the time of polarizing filter insertion) in the modification of 2nd Embodiment

  Hereinafter, a dome type camera according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a case of a dome type camera used for a surveillance camera or the like is illustrated.

(First embodiment)
The configuration of the dome type camera according to the first embodiment of the present invention will be described with reference to the drawings. 1 and 2 are explanatory diagrams of the dome type camera of the present embodiment. 3 and 4 are perspective views of the lens unit of the dome type camera according to the present embodiment.

  As shown in FIGS. 1 and 2, the dome type camera 1 includes a base 2 attached to a ceiling or a wall, and a dome cover 3 attached to the base 2. A lens unit 5 having a camera lens 4 is provided inside the dome cover 3. The lens unit 5 is housed in a housing constituted by the base 2 and the dome cover 3, and the camera lens 4 is covered by the dome cover 3. The camera lens 4 has a zoom function.

  The dome type camera 1 is provided with a pan motor and a tilt motor, and the lens unit 5 (camera lens 4) can be rotated in the pan direction and the tilt direction by the driving force of the pan motor and the tilt motor. The operation of these motors (pan motor, tilt motor) is controlled by a control unit such as a microcomputer.

  As shown in FIGS. 3 and 4, the lens unit 5 includes a polarizing filter 6. The polarization direction of the polarizing filter 6 is a vertical direction (longitudinal direction) or a horizontal direction (lateral direction). A support piece 8 having an arcuate guide portion 7 extends from the upper part of the polarizing filter 6. Two guide pins 9 project from the left and right side surfaces of the arcuate guide portion 7. A pair of left and right guide plates 10 are provided on the upper portion of the lens unit 5. The guide portion 7 of the support piece 8 is sandwiched between a pair of left and right guide plates 10, and the guide pins 9 are slidably inserted into arc-shaped elongated holes 11 provided in the guide plate 10.

  Then, when the guide pin 9 slides in the long hole 11 of the guide plate 10, the polarizing filter 6 is inserted into the insertion position (the position where the polarizing filter 6 is inserted in front of the camera lens 4 as shown in FIG. 3). ) And a retracted position (a position where the polarizing filter 6 is retracted from the front side of the camera lens 4 as shown in FIG. 4). The dome type camera 1 is provided with a filter motor, and the polarizing filter 6 is movable between an insertion position and a retracted position by a driving force of the filter motor. The operation of this filter motor is also controlled by a control unit such as a microcomputer.

  FIG. 5 shows a modification of the lens unit 5 of the present embodiment. In this modification, a partial light blocking filter 12 is used instead of the polarizing filter 6. The partial light blocking filter 12 is a light blocking filter that blocks a part of incident light. In this case, as shown in FIG. 5, the partial light shielding filter 12 has a light shielding area 13 that shields half of the field of view of the camera lens 4. This light-shielding area 13 is set in a half range on the side opposite to the zenith direction of the dome cover 3 (the lower side in FIG. 5).

  Next, the operation of the dome type camera 1 of the first embodiment configured as described above will be described with reference to the drawings.

  FIG. 6 is a diagram showing the relationship between the tilt angle and the offset amount and the relationship between the tilt angle and whether or not a filter is inserted in the dome type camera 1 of the present embodiment.

  Here, the tilt angle of the camera lens 4 (tilt angle of the lens unit 5) is based on the zenith direction of the dome cover 3. That is, the tilt angle is 0 degree when the camera lens 4 is directed toward the zenith direction of the dome cover 3, and is 90 degrees when the camera lens 4 is directed in the horizontal direction. Therefore, the tilt angle decreases as the camera lens 4 is directed toward the zenith direction of the dome cover 3, and the tilt angle increases as the camera lens 4 is directed from the zenith direction to the horizontal direction.

In this case, the offset amount x depends on the tilt angle θ. If the deviation amount between the center P1 of the dome cover 3 and the tilt rotation axis P2 is x0, the offset amount x is given by the following equation (see FIGS. 2 and 6).
x = x0 × sin θ

  Here, the case where the offset amount x depends on the tilt angle θ as shown in FIG. 6 is illustrated, but the scope of the present invention is not limited to this. For example, the offset amount has a tilt angle of 75 degrees. If it exceeds, the tilt rotation axis P2 may be changed by moving in the zenith direction.

  In the present embodiment, when the tilt angle of the camera lens 4 (tilt angle of the lens unit 5) is in the range of 0 ° to θs, the polarizing filter 6 is not inserted (the polarizing filter 6 remains in the retracted position). is there). When the tilt angle of the camera lens 4 (tilt angle of the lens unit 5) exceeds θs, the polarizing filter 6 is inserted (the polarizing filter 6 moves to the insertion position). Here, the tilt angle θs corresponds to the threshold angle of the present invention. The threshold angle θs can be set to an arbitrary value according to the use of the dome camera, the installation environment, and the like.

  FIG. 7 is a diagram showing the relationship between the zoom magnification and the presence or absence of filter insertion in the dome type camera 1 of the present embodiment. As shown in FIG. 7, when the zoom magnification is in the range of 1 to 10 times (the WIDE end side range), the polarizing filter 6 is not inserted (the polarizing filter 6 remains in the retracted position). When the zoom magnification enters a range exceeding 10 times (TELE end side range), the polarizing filter 6 is inserted (the polarizing filter 6 moves to the insertion position). Here, a zoom magnification of 10 corresponds to the threshold magnification of the present invention.

  The polarizing filter 6 is inserted when the tilt angle is in the large tilt angle range (a range exceeding 75 degrees) and the zoom magnification is in the TELE end side range (a range exceeding 10 times). Is called. That is, even when the tilt angle is in the large tilt angle range (for example, the tilt angle is 90 degrees), the polarization filter 6 is not inserted if the zoom magnification is in the WIDE end range.

  FIG. 8 shows a modification of filter insertion control with respect to the zoom magnification. As shown in FIG. 8, the filter insertion control may be performed with a predetermined hysteresis width. For example, when the zoom magnification changes from a small value (a value close to the WIDE end) to a large value (a value close to the TELE end), the polarizing filter 6 is inserted at the first threshold magnification z1, and the zoom magnification is a large value ( When changing from a value close to the TELE end) to a small value (a value close to the TELE end), the polarizing filter 6 may be retracted at the second threshold magnification z2 (z1 <z2).

  In the present embodiment, whether or not a filter is inserted depends on the tilt angle and the zoom magnification. FIG. 9 is a diagram schematically showing a region (filter insertion region) in which the polarizing filter 6 is inserted. As shown in FIG. 9, in the present embodiment, the filter insertion region is determined by the zoom magnification and the tilt angle.

  According to the dome type camera 1 of the first embodiment of the present invention as described above, when photographing in a direction with a large tilt angle (a direction close to the horizontal direction), it is possible to secure a wide field of view and reduce image quality degradation. It can be compatible.

  That is, in the present embodiment, since the tilt rotation axis P2 of the camera lens 4 (tilt rotation axis P2 of the lens unit 5) is in the zenith direction with respect to the center P1 of the dome cover 3, the tilt angle ( Even when the tilt angle of the lens unit 5 is increased, a wide horizontal field of view can be secured. In this case, when the tilt angle of the camera lens 4 (tilt angle of the lens unit 5) increases, the polarizing filter 6 is inserted on the optical axis of the camera lens 4. This polarizing filter 6 can suppress deterioration in image quality due to the offset of the camera lens 4 (the offset of the lens unit 5). As a result, when photographing in a direction with a large tilt angle (a direction close to the horizontal direction), it is possible to achieve both a wide field of view and a reduction in image quality degradation.

  In the present embodiment, when the zoom magnification of the camera lens 4 is set to the TELE end side, the polarizing filter 6 is inserted on the optical axis of the camera lens 4, and the polarizing filter 6 allows the camera lens 4 to be Degradation of image quality due to the offset (offset of the lens unit 5) can be suppressed. Note that when the zoom magnification of the camera lens 4 is set to the WIDE end side, there is little deterioration in image quality. In this case, the polarizing filter is used regardless of the tilt angle of the camera lens 4 (tilt angle of the lens unit 5). 6 and the partial light blocking filter 12 may not be inserted. Note that when a telephoto lens having a high magnification is attached, image quality deterioration can be suppressed by inserting the polarizing filter 6 and the partial light shielding filter 12 also on the WIDE end side.

  In the present embodiment, the polarizing filter 6 is inserted on the front side of the camera lens 4, and the light before entering the camera lens 4 is polarized by the polarizing lens. That is, the light polarized by the polarizing lens enters the camera lens 4. Thereby, it is possible to suppress the deterioration of the image quality due to the offset of the camera lens 4 (the offset of the lens unit 5).

  In the modified example of the present embodiment (modified example of FIG. 5), the partial light shielding filter 12 is used instead of the polarizing filter 6, but this modified example also provides the same operational effects as the present embodiment. The

  Further, in this modification, when photographing a direction with a large tilt angle (a direction close to the horizontal direction), the light shielding area 13 of the partial light shielding filter 12 causes the opposite side to the zenith direction of the dome cover 3 (the side with the large tilt angle). The half range of the side close to the horizontal direction is shielded from light. This light-shielded range is considered to correspond to a portion that is not so high in molding accuracy of the dome cover 3 and causes image quality deterioration. By shielding this portion, image quality deterioration can be suppressed.

(Second Embodiment)
Next, a dome type camera according to a second embodiment of the present invention will be described. Here, the dome type camera according to the second embodiment will be described focusing on differences from the first embodiment. Unless otherwise specified, the configuration and operation of the present embodiment are the same as those of the first embodiment.

  FIG. 10 is a perspective view of the camera unit of the dome type camera of the present embodiment, and FIGS. 11 to 13 are front views of the camera unit. The camera unit is a unit provided inside the lens unit, and includes a switching mechanism between an infrared cut filter and optical glass. The infrared cut filter is used during daytime shooting, and the optical glass is used during nighttime shooting.

  As shown in FIGS. 10 to 13, the camera unit 20 includes a filter frame 23 to which the infrared cut filter 21, the optical glass 22, and the polarizing filter 6 are attached. The filter frame 23 can be rotated by the driving force of the motor. Three rotation positions (polarization filter insertion position, infrared cut filter insertion position, and optical glass insertion position) are set in the filter frame 23.

  When the rotation position of the filter frame 23 is the polarization filter insertion position, the polarization filter 6 is inserted on the front side of the image sensor (see FIG. 11). Further, when the rotational position of the filter frame 23 is the infrared cut filter insertion position, the infrared cut filter 21 is inserted in front of the image sensor (see FIG. 12). When the rotation position of the filter frame 23 is the optical glass insertion position, the optical glass 22 is inserted into the front side of the image sensor (see FIG. 13).

  14 and 15 show a modification of the camera unit 20 according to the second embodiment. In this modification, the polarizing filter 6, the infrared cut filter 21, and the optical glass 22 are attached to separate filter frames 23, respectively, and can be independently rotated. In this case, only the infrared cut filter 21 (or only the optical glass 22) can be inserted as shown in FIG. 14, and the infrared cut filter 21 (or the optical glass 22) and the polarizing filter as shown in FIG. Both 6 can be inserted.

  Such a dome type camera 1 according to the second embodiment of the present invention also provides the same operational effects as those of the first embodiment.

  In addition, in the present embodiment, the polarizing filter 6 can be inserted using a switching mechanism between the infrared cut filter 21 and the optical glass 22. By utilizing the existing mechanism (switching mechanism between the infrared cut filter 21 and the optical glass 22), the number of parts can be reduced and the manufacturing cost can be reduced compared to the case where a dedicated mechanism is separately provided. Miniaturization is possible.

  The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified according to the purpose within the scope of the claims. is there.

  As described above, the dome camera according to the present invention can achieve both a wide field of view and a reduction in image quality degradation when photographing in a direction with a large tilt angle (a direction close to the horizontal direction). It is useful as a surveillance camera.

DESCRIPTION OF SYMBOLS 1 Dome type camera 2 Base 3 Dome cover 4 Camera lens 5 Lens unit 6 Polarizing filter 7 Guide part 8 Support piece 9 Guide pin 10 Guide plate 11 Slot 12 Partial light shielding filter 13 Light shielding area 20 Camera unit 21 Infrared cut filter 22 Optical glass 23 Filter frame P1 Center of dome cover P2 Tilt rotation axis

Claims (2)

A spherical cover,
A camera lens provided inside the spherical cover and rotatable in a tilt direction ;
A light shielding part that shields a part of the incident light to the camera lens ,
If the tilt angle before Symbol camera lens exceeds a predetermined threshold angle, the dome camera to be inserted between the light shielding portion by moving the spherical cover and the camera lens,
The dome type camera , wherein the threshold angle can be set to an arbitrary value . A lens unit having the camera lens;
2. The dome type camera according to claim 1, wherein a tilt rotation axis of the lens unit is located in a zenith direction from a spherical center position of the spherical cover.

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