JP2005250276A - Lens device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a lens device, which has an optical member to be moved back or forth on the optical path of a lens, compact in structure. <P>SOLUTION: A near infrared light cut filter 12 to be advanced/retreated to/from the optical path of a relay lens 28 is divided into an upper filter 12A and a lower filter 12B so that the divided upper and filters 12A, 12B can be freely moved to a mutually approaching direction or to a mutually separating direction. These upper and lower filters 12A, 12B are moved to the mutually approaching direction by the power of a motor 48 to advance the near infrared light cut filter 12 to the optical path of the relay lens 28 or these upper and lower filters 12A, 12B are moved to the mutually separating direction to retreat the filter 12 from the optical path of the relay lens 28. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens device, and more particularly to a lens device for a surveillance camera, which can be used in a wavelength range from a visible light wavelength range of daylight to a near-infrared wavelength range of night light. Relates to the device.

  Surveillance cameras perform color photography by imaging light in the visible light region on the imaging surface of the image sensor provided in the camera body during the day, and in the near infrared wavelength region at night in addition to the light in the visible light region. The light is imaged for monochrome photography, and a monitoring image is displayed on the TV monitor.

  In general, an optical system of a lens apparatus is designed according to a wavelength range to be used, and when used in a wavelength range other than that, an imaging position is shifted due to the influence of chromatic aberration. For this reason, a lens device for a surveillance camera used in both the daylight visible light wavelength range (about 400 nm to about 700 nm) and the night light near infrared wavelength range (about 700 nm to about 1000 nm) is used. It is necessary to correct the imaging position according to the wavelength range.

  Therefore, conventionally, an infrared cut filter that corrects the deviation of the image formation position in daylight is placed between the optical system of the lens device and the image sensor, and moves forward and backward in a plane orthogonal to the optical path of the optical system. A lens device provided freely is known (for example, Patent Document 1).

  FIG. 6 is a schematic diagram of an infrared cut filter advance / retreat structure. This figure shows the rear end of the lens barrel 1, and the infrared cut filter 2 is held in a circular opening 3 </ b> A of a rectangular holding frame 3. A dummy glass 4 through which light simply passes is attached to the opening 3B adjacent to the opening 3A. The holding frame 3 is provided so as to be slidable within a plane perpendicular to the optical axis P of the photographing optical system 5 in a cylindrical space in the lens barrel 1 of the lens apparatus. In the state of FIG. 6, the dummy glass 4 is positioned on the optical path of the photographing optical system 5. When switching from this state to daylight, the holding frame 3 is slid in the direction of arrow A to cut the infrared rays. The filter 2 is positioned on the optical path.

When correcting the shift of the imaging position in the night light, a visible light cut filter may be attached to the opening 3B of the holding frame 3, but the surveillance camera may perform near infrared illumination at night. In this case, the visible light cut filter is omitted, and the dummy glass 4 is attached to the holding frame 3 as shown in FIG. Further, the opening 3B may be a through hole without attaching the dummy glass 4.
JP 2001-255444 A

  However, the conventional lens device for moving the infrared cut filter 2 forward and backward with respect to the optical path of the photographing optical system 5 has a retracting space for the infrared cut filter 2 on one side and a dummy on the other side across the photographing optical system 5. Since a retreat space for the glass 4 is required, the outer diameter D of the lens barrel 1 becomes large, and there is a disadvantage that the lens device becomes large.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lens device having a compact structure in a lens device in which an optical member is moved back and forth in the optical path of the lens.

  In order to achieve the above object, the present invention moves the optical member forward and backward relative to the optical path of the lens holding frame, the optical member, and the lens held in the lens holding frame. The optical device is divided into two parts, and the one optical member and the other optical member divided into two are provided so as to be movable in a direction toward and away from each other. It is characterized by being moved forward in the optical path of the lens by being moved in a direction approaching each other by the advancing and retreating means, and retracted from the optical path of the lens by being moved away from each other.

  According to the first aspect of the present invention, the optical member is divided into two parts, and the two divided optical members and the other optical member are provided so as to be movable toward and away from each other, and these optical members are moved forward and backward. By moving in a direction approaching each other by means, the advancing position is placed in the optical path of the lens, and by moving in a direction away from each other, the lens is retracted from the optical path of the lens.

  Here, the lens barrel diameter of the lens apparatus of the present invention is compared with the lens barrel diameter of the conventional lens apparatus. Assuming that the lens diameter is d, the conventional lens apparatus has a retreat space for the infrared cut filter 2 having a diameter substantially equal to the lens diameter d on both sides of the lens, and a dummy glass 4 having a diameter substantially equal to the lens diameter d. Therefore, the lens barrel diameter D of the conventional lens device is 3d. On the other hand, the lens device of the present invention in which the optical member is divided into two only needs to provide a retracting space for the optical member having a lens diameter of about d / 2 on both sides of the lens, so that the lens barrel diameter is 2d. Become. Therefore, since the diameter is about two thirds of the diameter of the conventional lens barrel, the lens device becomes compact.

  According to a second aspect of the present invention, the optical member is an image position correcting member that corrects a shift in image position in daylight or night light. By applying the lens device of the present invention to a monitoring camera and using the optical member as the imaging position correcting member, it is possible to obtain a clear image in focus at daytime or nighttime.

  The invention according to claim 3 is characterized in that the imaging position correcting member is a near-infrared light cut filter or a visible light cut filter. By bringing the near-infrared light cut filter into the optical path of the lens at daytime, a clear image in focus at daytime can be obtained. Alternatively, a clear image focused at night can be obtained by moving the visible light cut filter into the optical path of the lens at night.

  According to a fourth aspect of the present invention, the forward / backward moving means includes a first arm on which a holding frame for holding the one optical member is formed and a second arm on which the holding frame for holding the other optical member is formed. A rotation support part that supports the first arm and the second arm in opposite directions to each other, and a rotation support part that supports the first arm and the second arm. And a drive source for supplying power to the power transmission mechanism. When the power of the drive source is applied to the power transmission mechanism, the first arm and the second arm rotate in opposite directions, so that one optical member and the other optical member move forward and backward with respect to the optical path of the lens. To do. By providing such a power transmission mechanism, the one and the other divided optical members can be interlocked with each other in a direction toward and away from each other with a single drive source.

  According to the lens device of the present invention, in the lens device having an optical member that is moved back and forth in the optical path of the lens, the optical member is divided into two, and one optical member and the other optical member are mutually connected with respect to the optical path of the lens. Since it is moved back and forth, a compact lens device can be provided.

  Hereinafter, preferred embodiments of a lens apparatus according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing the structure of a base end portion of a surveillance camera lens device 10 to which the present invention is applied, in a state where a near-infrared light cut filter 12 as an optical member has advanced into the optical path of the lens. It is shown schematically. FIG. 2 is a cross-sectional view schematically showing a state in which the near-infrared light cut filter 12 is retracted from the optical path of the lens. 3 is a perspective view of the near infrared light cut filter 12 shown in FIG. 1 as viewed from the rear side of the lens, and FIG. 4 shows the near infrared light cut filter 12 shown in FIG. It is the perspective view seen from the back side.

  In the embodiment, the lens device 10 to which only the near-infrared light cut filter 12 is attached is illustrated as an imaging position correcting member that is an optical member. Since this lens device 10 is for a surveillance camera installed at a surveillance location where near infrared illumination is performed at night, a visible light cut filter is omitted. Further, depending on the specification that does not perform near-infrared illumination, a visible light cut filter is attached instead of the near infrared light cut filter 12. Furthermore, an optical path length correction glass having an optical path length equivalent to those of these filters may be used, or a near infrared light cut lens or a visible light cut lens may be used.

  As shown in FIGS. 1 and 2, a substantially cylindrical lens holding frame 16 is provided inside a fixed barrel 14 constituting the lens device 10, and a C mount ring 18 is provided on the outside of the lens holding frame 16 with an optical axis. It is arranged so as to be rotatable around P. The male screw portion 20 formed at the base end portion of the C mount ring 18 is screwed into the female screw portion 24 of the surveillance camera main body 22 indicated by a two-dot chain line in FIGS. It is attached to the main body 22. As a result, the surveillance camera is assembled, and the subject image captured by the lens device 10 is formed on the imaging surface of the solid-state imaging device 24 of the surveillance camera body 22.

  The lens holding frame 16 holds a relay lens 28 arranged in the last row of the imaging optical system of the lens device 10. Further, a screw portion 30 is formed on the outer periphery of the fixed lens barrel 14, and a screw ring 32 for fixing the C mount ring 18 to the fixed lens barrel 14 in a non-rotatable manner is screwed into the screw portion 30. . That is, a stepped portion 34 is formed on the inner peripheral portion of the screw ring 32, and the stepped portion 34 is engaged with a stepped portion 36 formed on the outer peripheral portion of the C mount ring 18. Further, a stepped portion 38 is also formed in the inner peripheral portion of the C mount ring 18, and this stepped portion 38 is formed when the C mount ring 18 is slid leftward in FIG. It abuts on the right end surface 15 of the fixed lens barrel 14. When the screw ring 32 is screwed into the screw part 30 in this state, the C mount ring 18 is pressed leftward in FIG. 1 by the step part 34, so that the step part 38 becomes the right end surface 15 of the fixed barrel 14. Pressure contacted. As a result, the C mount ring 18 is fixed to the fixed barrel 14 so as not to rotate.

  The near-infrared light cut filter 12 moved forward and backward with respect to the optical path behind the relay lens 28 is formed in a rectangular shape having an area larger than the surface area of the relay lens 28 as shown in FIG. The near-infrared light cut filter 12 is divided into upper and lower parts and includes an upper filter (one optical member) 12A and a lower filter (the other optical member) 12B. Further, the near-infrared light cut filter 12 is a gelatin filter, and the upper filter 12A is held by a frame 31 having a concave shape on the upper side and the left and right sides, and the lower film 12B is concave on the lower side and the left and right sides. The frame 33 is held in a shape. These frames 31 and 33 are in the state of FIG. 3 where the lower side of the upper filter 12A and the upper side of the lower filter 12B are in contact, that is, in the state where the near-infrared light cut filter 12 has entered the optical path of the relay lens 28. The frames 31 and 33 are configured so as not to enter the optical path. The near-infrared light cut filter 12 may be divided into left and right parts and moved forward and backward with respect to the optical path of the relay lens 28.

  The upper filter 12A and the lower filter 12B are disposed in a substantially mortar-shaped space 17 formed between the fixed barrel 14 and the lens holding frame 16. Further, in this space 17, the upper filter 12A and the lower filter 12B are moved in a direction approaching each other with respect to the optical path of the relay lens 28 by an advancing / retreating device (advance / retreat means) 40 shown in FIGS. And are moved away from each other (see FIG. 2).

  As shown in FIGS. 3 and 4, the advancing / retreating device 40 includes rotation support portions 42 and 44, a power transmission mechanism 46, a motor (power source) 48, and the like. The rotation support portions 42 and 44 are support portions that support the upper filter 12A and the lower film 12B so as to be movable forward and backward with respect to the optical path of the relay lens 28. The rotation support portion 42 includes a rotation shaft 54 fixed to an end portion of the arm 50 among a pair of arms (first arms) 50 and 52 integrally formed with the frame 31 that holds the upper filter 12A. Have. The rotating shaft 54 is disposed in a direction orthogonal to the optical axis P in the horizontal plane. The arms 50 and 52 are connected to both ends of the frame 31 and extend toward the subject side in parallel with the optical axis P. Therefore, when the rotating shaft 54 is rotated around the axis 54A, the upper filter 12A is moved along a circular locus having the radius of the arm 50 centered on the axis 54A of the rotating shaft 54.

  The other rotation support portion 44 is a rotation shaft (fixed to an end portion of the arm 56 of a pair of arms (second arms) 56, 58 formed integrally with the frame 33 holding the lower filter 12B). (Not shown). The rotating shaft (not shown) is disposed in a direction orthogonal to the optical axis P in the horizontal plane and is disposed coaxially with the rotating shaft 54. The arms 56 and 58 are connected to both ends of the frame 33 and extend toward the subject in parallel with the optical axis P. Therefore, when the rotation shaft (not shown) is rotated around its axis, the lower filter 12B is moved along a circular locus whose radius is the arm 56 about the axis of the rotation shaft (not shown). The

  Since the axis of the rotation shaft (not shown) and the axis 54A of the rotation shaft 54 are coaxially positioned and the lengths of the arms 50 and 56 are equal, the upper filter 12A and the lower filter 12B have the same circular locus. Is moved along. The arm 52 on the upper filter 12A side is rotatably supported by the rotation shaft (not shown), and power from the rotation shaft (not shown) is not transmitted. Similarly, the arm 58 on the lower filter 12B side is also rotatably supported by the rotating shaft 54, and the power from the rotating shaft 54 is not transmitted. One end of the rotation shaft 54 and a rotation shaft (not shown) are rotatably supported by the fixed lens barrel 14 and the other end of the rotation shaft 54 by the lens holding frame 16.

  The power transmission mechanism 46 is composed of a plurality of gears, and transmits power for rotating the arms 50 and 56 supported by the rotation support portions 42 and 44 in opposite directions. That is, a gear 60 is fixed to the rotating shaft (not shown), and a gear 62 is fixed to the rotating shaft 54. An idler gear 64 is engaged with the gear 62, and the idler gear 64 is engaged with the gear 66. A bevel gear 70 is fixed inside the gear 66 to the rotation shaft 68 of the gear 66, and the bevel gear 70 is meshed with a bevel gear 72 fixed to a motor shaft 49 of the motor 48. A gear 74 is fixed to the opposite side of the gear 66 across the lens holding frame 16 of the rotating shaft 68, and the gear 74 is meshed with the gear 60 without an idler gear. Therefore, when the rotational power of the motor 48 is applied to the power transmission mechanism 46, the arms 50 and 56 are rotated in synchronization with each other in the opposite directions by the reverse operation of the idler gear 64. Accordingly, the upper filter 12A and the lower filter 12B move forward and backward in synchronization with the optical path of the relay lens 28, and are simultaneously positioned at the advanced position shown in FIG. 1 and the retracted position shown in FIG.

  The motor 48 is a motor with a brake, that is, has a function of braking the motor shaft 49 when the motor shaft 49 stops. The motor 48 is mainly controlled by a command signal from a controller that remotely controls the surveillance camera. Further, the motor 48 is controlled to stop based on signals from limit switches 76 and 78 that are pressed by the frames 31 and 33 at the retracted positions of the upper filter 12A and the lower filter 12B (see FIG. 2). Further, in the advanced position of the upper filter 12A and the lower filter 12B (see FIG. 1), a limit switch that is pressed and turned ON at that position is provided in the same manner as the retracted position, and the motor is based on the signal from the limit switch. 48 may be controlled to stop, or the motor 48 may be provided with a torque limiter, and the motor 48 may be controlled to stop when it is determined that the torque limiter is located at the advanced position when it detects an overcurrent.

  Next, the operation of the monitoring camera lens apparatus 10 configured as described above will be described.

  First, in the case of night photography, the upper filter 12A and the lower filter 12B of the near-infrared light cut filter 12 are positioned at the retracted positions in FIGS. As a result, the optical image captured by the lens device 10 is formed on the imaging surface of the solid-state image sensor 26. Therefore, a clear image can be obtained in night photography.

  When switched to daytime shooting, the motor 48 is driven to move the upper filter 12A and the lower filter 12B of the near-infrared light cut filter 58 into the optical path of the relay lens 28 as shown in FIGS. As a result, the near-infrared wavelength region component captured by the lens device 10 is cut by the near-infrared light cut filter 12, and the optical image from which the near-infrared wavelength region component is cut is connected to the imaging surface of the solid-state imaging device 26. Imaged. By inserting the near-infrared light cut filter 12, the shift of the imaging position accompanying the shift from night photography to daytime photography is corrected, and a clear image can be obtained even during daytime photography.

  Here, the fixed lens barrel diameter of the lens device 10 of the embodiment is compared with the lens barrel diameter of the conventional lens device shown in FIG. When the diameter of the lens (relay lens 28 in the case of the lens device 10 of the embodiment, imaging optical system 5 in the case of the conventional lens device) is d, the conventional lens device has a lens diameter d on both sides of the lens. And a retracting space for the dummy glass 4 having a diameter substantially equal to the lens diameter d, and a lens barrel diameter D of the conventional lens apparatus is 3d. Become.

  On the other hand, in the lens apparatus 10 according to the embodiment in which the near-infrared light cut filter 12 is divided into two parts, an upper filter 12A having a relay lens diameter of about d / 2 above and below the relay lens 28 as shown in FIG. Since it is only necessary to provide a retreat space for the lower filter 12B, the lens barrel diameter D is 2d. Therefore, since the diameter is about two thirds of the diameter of the conventional lens barrel, the lens device becomes compact.

Cross-sectional view of the lens apparatus schematically showing a state in which the near-infrared light cut filter has advanced into the optical path of the lens Sectional view of the lens apparatus schematically showing a state in which the near-infrared light cut filter is retracted from the optical path of the lens The perspective view which looked at the near-infrared light cut filter shown in FIG. The perspective view which looked at the near-infrared light cut filter shown in FIG. The schematic diagram which looked at the lens apparatus of embodiment from the rear part of a fixed barrel Schematic view of a conventional lens device viewed from the rear of the lens barrel

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Lens apparatus, 12 ... Near-infrared light cut filter, 12A ... Upper filter, 12B ... Lower filter, 14 ... Fixed lens barrel, 16 ... Lens holding frame, 28 ... Relay lens, 31, 33 ... Frame, 42, 44 ... Rotation support, 46 ... Power transmission mechanism, 48 ... Motor, 50, 52, 56, 58 ... Arm, 76, 78 ... Limit switch

Claims (4)

In a lens apparatus comprising a lens holding frame disposed inside a lens barrel, an optical member, and an advancing / retreating means for moving the optical member forward and backward with respect to the optical path of the lens held by the lens holding frame,
The optical member is divided into two parts, and the one optical member and the other optical member divided into two parts are provided so as to be movable toward and away from each other, and are moved toward each other by the forward / backward moving means. The lens apparatus is moved forward in the optical path of the lens and moved away from the optical path of the lens by being moved away from each other. The lens apparatus according to claim 1, wherein the optical member is an imaging position correcting member that corrects a deviation of an imaging position in daylight or nightlight. The lens apparatus according to claim 2, wherein the imaging position correcting member is a near-infrared light cut filter or a visible light cut filter. The forward / backward moving means pivots on the same axis a first arm on which a holding frame for holding the one optical member is formed and a second arm on which a holding frame for holding the other optical member is formed. A pivot support section that freely supports, a power transmission mechanism that transmits power to rotate the first arm and the second arm supported by the pivot support section in directions opposite to each other, and the power transmission The lens apparatus according to claim 1, further comprising: a drive source that supplies power to the mechanism.

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