JP4749869B2 - Lens displacement device - Google Patents

Description

  The present invention relates to a lens displacement device that displaces a lens by transmitting a displacement of a rack member in a driving mechanism to a lens holding portion that holds the lens.

  In general, since a video camera is equipped with an autofocus mechanism or a zoom mechanism, it incorporates a lens displacement device that displaces the lens. This lens displacement device normally includes a drive motor, a drive mechanism having a lead screw rotated by the drive motor, and a rack member meshed with the lead screw, and a lens holding portion for holding the lens by the displacement of the rack member. To communicate.

In addition, this type of lens displacement device includes a tooth jump prevention portion that prevents a so-called tooth jump phenomenon in which the rack member slips over the teeth in the axial direction of the lead screw due to vibration or impact. Conventionally, as such a tooth jump prevention part, a tooth jump prevention part built in a lens driving device (lens displacement device) disclosed in Japanese Patent Laid-Open No. 2000-98210 is known. This lens driving device uses a nut in which a rack part, a leaf spring part, a tooth jump prevention part, a hinge part, and a base part are integrally formed of plastic. The leaf spring part is pressed against the lead screw meshed with the rack part, and the tooth jump prevention part regulates the position of the lead screw so that the lead screw is not separated from the rack part. .
JP 2000-98210 A

  However, the above-described conventional lens displacement device (lens driving device) has the following problems.

  First, since the tooth skip prevention part is configured as a mere regulating member, sufficient tooth jump prevention cannot be achieved. In particular, in the case of a surveillance camera (surveillance video camera) in which the shooting direction (shooting angle) is variably controlled by remote control, the impact at the start and stop when changing the angle is large, so tooth jumping is ensured. It cannot be prevented. Note that tooth skipping can be reliably prevented by using a normal nut with spiral teeth, but since position control cannot be performed smoothly and with high accuracy, this type of lens displacement device has a lead screw and a rack portion. It is used.

  Secondly, the mechanical mechanism between the lens holding part and the rack part needs to eliminate backlash and improve followability and control accuracy, but the above-mentioned conventional mechanical mechanism is supported by a hinge part made of thin plastic. Therefore, good elasticity cannot be secured, and eventually sufficient followability cannot be secured and sufficient mechanical strength cannot be secured.

  An object of the present invention is to provide a lens displacement device that solves such problems in the background art.

  In order to solve the above-described problems, the present invention includes a drive motor 3, a drive mechanism 2 having a lead screw 4 rotated by the drive motor 3, and a rack member 5 meshed with the lead screw 4. A pair of bearings provided on the lens holding portion 6 (6z) (one connecting side) when the lens displacement device 1 is configured to displace the lens by transmitting the displacement to the lens holding portion 6 (6z) holding the lens. Part 13a, 13b and a pair of shaft parts 14a, 14b provided on the rack member 5 (the other connecting side), and at least one of the shaft parts 14b is an elastic projecting piece 15b formed on the rack member 5. By providing at the front end side, the pair of shaft portions 14a and 14b are inserted into the pair of bearing portions 13a and 13b from the inside so that the rack member 5 and the lens holding portion 6 (6z) can be rotated. In addition to the rotation connecting portion 7 to be connected, a coil spring 8c in a compressed state is interposed between the pair of shaft portions 14a and 14b, and a locking portion 33a at one end of the coil spring 8c is attached to the lens holding portion 6 (6z). By locking and locking the locking portion 33b at the other end to the rack member 5, one connecting side of the rotating connecting portion 7 is brought into pressure contact with the other connecting side by the elasticity of the coil spring 8c in the axial direction. The first urging means is configured, and the second urging means is configured to press the rack member 5 against the lead screw 4 by elasticity in the circumferential direction (twisting direction).

  In this case, according to a preferred aspect of the invention, the rack member 5 includes a rack plate portion 11 that meshes with the lead screw 4, and the rack plate portion 11 that faces the rack plate portion 11 and sandwiches the lead screw 4. One or more screw restricting portions 12a and 12b for restricting the position can be provided. The lens can include one or both of a focus lens group Lf constituting the autofocus mechanism 16 and a zoom lens group Lz constituting the zoom mechanism 17.

  According to the lens displacement device 1 according to the present invention having such a configuration, the following remarkable effects can be obtained.

  (1) Since the rack member 5 rotatably supported by the rotation connecting portion 7 is pressed against the lead screw 4 by the coil spring 8c (second urging means), vibration or impact is applied. However, the relatively light rack member 5 can always be pressed against (followed by) the lead screw 4, so that it is possible to reliably prevent tooth jumping. Therefore, it is most suitable for a surveillance camera that variably controls the shooting direction (shooting angle) by remote control.

  (2) Because of the coil spring 8c (first urging means), one coupling side of the rotation coupling unit 7 is pressed against the other coupling side, so that the mechanical mechanism is loose between the lens holding unit 6 and the rack member 5. In addition, the followability and control accuracy can be improved, and sufficient mechanical strength can be secured. Further, even if there is a clearance variation between the lens holding portion 6 and the guide shaft that slidably supports the lens holding portion 6, the coil spring 8c urges the device to eliminate rattling and facilitate clearance management. In addition, the reliability with respect to the change in the vertical posture of the lens and the low temperature operation can be improved.

  (3) Since it is sufficient to use a single coil spring 8c serving both as the first urging means and the second urging means, it is possible to reduce the number of manufacturing steps, reduce the cost, and reduce the size due to the effect of reducing the parts used. .

  (4) The rotation connecting portion 7 includes a pair of bearing portions 13a and 13b provided on the lens holding portion 6 (one connecting side) and a pair of shaft portions 14a provided on the rack member 5 (the other connecting side). Since it comprises 14b, it can implement | achieve the stable connection structure by the combination with the coil spring 8c.

  (5) Since the coil spring 8c interposed between the pair of shaft portions 14a and 14b is used, the elasticity in the axial direction Fs of the coil spring 8c is used as the first biasing means, and the elasticity in the circumferential direction (twisting direction) Ff. Can be used as the second urging means, and the lens displacement device 1 according to the present invention can be reliably implemented in the most desirable form.

  (6) According to a preferred embodiment, the rack member 5 meshes with the lead screw 4 on the rack member 5, and the position of the lead screw 4 is restricted by sandwiching the lead screw 4 while facing the rack plate portion 11. If one or two or more screw restricting portions 12a and 12b are provided, the screw restricting portions 12a and 12b can function as a conventional tooth skip preventing portion, so that the tooth jump preventing effect can be further enhanced.

  (7) If the lens includes one or both of the focus lens group Lf constituting the autofocus mechanism 16 and the zoom lens group Lz constituting the zoom mechanism 17 according to a preferred embodiment, the autofocus mechanism 16 and the zoom mechanism 17 are included. It is possible to guarantee a stable operation with no tooth jumping.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the structure of the lens displacement apparatus 1 which concerns on this embodiment is demonstrated with reference to FIGS.

  FIG. 7 shows a main part of the lens unit M in the surveillance camera (surveillance video camera). The lens unit M includes single lenses L2, L3, L4, L5, L6, and L9, and includes cemented lenses L1, L7, L8, and L10. Among these, the cemented lens L8 becomes a focus lens group Lf used for the autofocus mechanism 16, and is held by the lens holding unit 6. The lens holding portion 6 integrally includes a pair of slider portions 6p and 6q provided at positions opposed to each other by 180 °, and the slider portions 6p and 6q are slidably supported in the front-rear direction by a pair of guide shafts 21p and 21q, respectively. Is done. And the lens displacement apparatus 1 which concerns on this embodiment is attached to one slider part 6p.

  As shown in FIG. 1, the lens displacement device 1 has a drive mechanism 2 including a drive motor 3, a lead screw 4 rotated by the drive motor 3, and a rack member 5 meshed with the lead screw 4. Is provided. The rack member 5 is connected to the slider portion 6q of the lens holding portion 6 described above via the rotation connection portion 7, and the rotation connection portion 7 includes a spring 8.

  In this case, the driving motor 3 uses a stepping motor 3s. This stepping motor 3s rotates by an angle corresponding to the number of pulses of the supplied drive current. Moreover, the lead screw 4 forms a female screw on the outer peripheral surface, and one end is coupled to the rotating shaft of the stepping motor 3s. On the other hand, the rack member 5 is integrally formed of a plastic material as a whole, and as shown in FIGS. 5 and 6, a rack body 31, a rack plate 11 protruding from one side of the rack body 31, and a rack It has two screw restricting portions 12 a and 12 b that protrude from the main body portion 31 and face the rack plate portion 11. As a result, the rack body 31, the rack plate 11 and the screw restricting portions 12 a and 12 b are U-shaped when viewed from the axial direction of the lead screw 4 as shown in FIG. It can be loaded between the part 11 and the screw restricting parts 12a and 12b. As a result, the lead screw 4 is sandwiched between the rack plate portion 11 and the screw restricting portions 12 a and 12 b and meshes with the rack plate portion 11. And screw control part 12a, 12b functions as a conventional tooth jump prevention part, and a tooth jump prevention effect is heightened more.

  Further, the rotation connecting portion 7 includes a pair of bearing portions 13a and 13b provided on the lens holding portion 6 on one connection side, and a pair of shaft portions 14a and 14b provided on the rack member 5 on the other connection side. Is provided. In this case, a pair of projecting pieces 15a and 15b are formed from the rack body portion 31 of the rack member 5, and the shaft portions 14a and 14b are provided on the outer surfaces of the projecting pieces 15a and 15b on the distal end side. At this time, the one protruding piece 15b is formed relatively long, and a slit 15bs is formed on the intermediate surface to function as the elastic protruding piece 15b. Further, projecting spring mounting portions 32 a and 32 b for holding the spring 8 are provided on the inner surface of the protruding piece 15 a and the elastic protruding piece 15 b located between the shaft portions 14 a and 14 b. Thus, as shown in FIG. 2, the pair of shaft portions 14 a and 14 b can be inserted from the inside into the pair of bearing portions 13 a and 13 b, and the rack member 5 can be rotated by the lens holding portion 6. Supported. With such a configuration, a stable connection structure by combination with the spring 8 can be realized.

  On the other hand, the spring 8 uses a coil spring 8c shown in FIG. Both ends of the coil spring 8c are formed as locking portions 33a and 33b. As shown in FIG. 2, the coil spring 8c is loaded in a compressed state between the pair of shaft portions 14a and 14b by attaching both ends to the spring mounting portions 32a and 32b. Then, the locking portion 33a on one end side is locked to the slider portion 6p (lens holding portion 6), and the locking portion 33b on the other end side is locked to the elastic protruding piece 15b (rack member 5). By using such a coil spring 8c, the lens displacement device 1 can be reliably implemented in the most desirable form.

  Next, the function (operation) of the lens displacement device 1 according to the present embodiment will be described with reference to the drawings.

  First, since the coil spring 8c is interposed between the pair of shaft portions 14a and 14b, that is, between the protruding piece 15a and the elastic protruding piece 15b in a compressed state, the elastic protruding piece 15b is urged in a direction of spreading outward. The protruding piece 15a and the elastic protruding piece 15b are in pressure contact with the inner side surfaces of the bearing portions 13a and 13b, respectively. Therefore, there is no backlash in the mechanical mechanism between the lens holding part 6 and the rack member 5, the followability and control accuracy are improved, and sufficient mechanical strength is ensured. In this case, the elasticity of the coil spring 8c in the axial direction Fs (FIG. 4) functions as the first biasing means.

  Further, the locking portion 33a on one end side of the coil spring 8c is locked on the slider portion 6p (lens holding portion 6), and the locking portion 33b on the other end side is locked on the elastic protruding piece 15b (rack member 5). Therefore, by selecting the positions (relative angles) of the locking portions 33a and 33b in the natural state, the rack member 5 is urged in the rotation direction with the rotation connecting portion 7 as a fulcrum, and the rack plate portion 11 is moved to the lead screw. 4 can be pressed. Therefore, even when vibration or impact is applied, the relatively light rack member 5 can always be pressed against (followed by) the lead screw 4, and reliable tooth jump prevention can be achieved. In this case, the elasticity in the circumferential direction, that is, the twisting direction Ff (FIG. 4) functions as the second urging means.

  Thus, since the coil spring 8c serves as both the first urging means and the second urging means, it is sufficient to use a single spring. Due to the effect of reducing the parts used, the number of manufacturing steps can be reduced, the cost can be reduced, and the size can be reduced. Can be achieved. Even if there is a variation in the clearance between the lens holding portion 6 (slider portions 6p and 6q) and the guide shafts 21p and 21q that slidably support the slider portions 6p and 6q due to the function of the coil spring 8c. Since it is urged by the coil spring 8c, rattling can be eliminated, clearance management can be facilitated, and reliability with respect to changes in the vertical posture of the lens and low-temperature operation can be improved.

  On the other hand, the basic operation of the lens displacement device 1 is as follows. First, the operation of the stepping motor 3s causes the lead screw 4 to rotate forward or backward. As a result, the rack member 5 and the lens holding portion 6 connected to the rack member 5 via the rotation connecting portion 7 are displaced in the front-rear direction along the guide shafts 21p and 21q. Accordingly, the focus lens group Lf held by the lens holding unit 6 is displaced in the front-rear direction, and normal focus adjustment is performed. At this time, the displacement stroke (stroke amount) of the lens holding unit 6 is controlled by the number of pulses of the drive current supplied to the stepping motor 3s. Therefore, the start position of the lens holding portion 6 is detected by a position sensor (not shown), and the zero position is calibrated to ensure an accurate stroke amount.

  Although the autofocus mechanism 16 has been described, a similar configuration can be adopted for the zoom mechanism 17 as shown in FIG. That is, the single lenses L3, L4, and L5 shown in FIG. 7 become the zoom lens group Lz used for the zoom mechanism 17, and are held by the lens holding unit 6z. The lens holding portion 6z integrally includes a pair of slider portions 6zp and 6zq provided at positions opposed to 180 °, and the slider portions 6zp and 6zq are supported by the guide shafts 22p and 22q so as to be slidable in the front-rear direction. . And the lens displacement apparatus 1 which concerns on this embodiment is attached to one slider part 6zp. In this case, the basic configuration of the lens displacement device 1 is the same as that of the lens displacement device 1 in the above-described autofocus mechanism 16 except for the length of the lead screw 4.

  By applying the lens displacement device 1 according to the present embodiment to the autofocus mechanism 16 and the zoom mechanism 17 as described above, it is possible to guarantee a stable operation in which no skipping occurs in the autofocus mechanism 16 and the zoom mechanism 17. Therefore, it is most suitable for a surveillance camera that variably controls the shooting direction (shooting angle) by remote control.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and the scope of the present invention is not deviated from the gist of the present invention in the detailed configuration, shape, material, quantity, and the like. It can be changed, added, or deleted arbitrarily.

  For example, although the case where the two screw restricting portions 12a and 12b are provided in the rack member 5 is shown, one or three or more may be used, or other restricting portions may be substituted. The lens displacement device 1 is optimally used for a surveillance camera, but is not necessarily limited to a surveillance camera, and is similarly used for various video cameras such as other home video cameras and commercial video cameras. Can do.

The perspective view of the lens displacement device concerning the best embodiment of the present invention, Partial cross-sectional side view of the lens displacement device, Partial cross-sectional front view of the lens displacement device, A perspective view of a coil spring used in the lens displacement device, A cross-sectional plan view of a rack member used in the lens displacement device, Sectional side view of a rack member used for the lens displacement device, The main part extraction block diagram of a lens unit provided with the lens displacement device,

Explanation of symbols

  1: lens displacement device, 2: drive mechanism, 3: drive motor, 4: lead screw, 5: rack member, 6: lens holding portion, 6z: lens holding portion, 7: rotating connecting portion, 8c: coil spring, 11: Rack plate portion, 12a: Screw restricting portion, 12b: Screw restricting portion, 13a: Bearing portion, 13b: Bearing portion, 14a: Shaft portion, 14b: Shaft portion, 15b: Elastic protruding piece, 16: Auto focus mechanism, 17: Zoom mechanism, 33a: Locking portion at one end of the coil spring, 33b: Locking portion at the other end of the coil spring, Fs: Axial direction of the coil spring, Ff: Circumferential direction (twisting direction) of the coil spring, Lf: Focus lens group, Lz: Zoom lens group

Claims (3)

  A drive mechanism having a drive motor, a lead screw rotated by the drive motor, and a rack member meshed with the lead screw, and transmitting the displacement of the rack member to a lens holding unit that holds the lens to displace the lens; The lens displacement device includes a pair of bearing portions provided on the lens holding portion (one connection side) and a pair of shaft portions provided on the rack member (the other connection side), and at least one shaft The portion is provided on the distal end side of the elastic protruding piece formed on the rack member, so that the pair of shaft portions are inserted into the pair of bearing portions from the inside, and the rack member and the lens holding portion are rotatably connected. And a compression coil spring is interposed between the pair of shaft portions, and a locking portion at one end of the coil spring is used as the lens holding portion. By locking and locking the locking portion at the other end to the rack member, the first connecting side of the rotating connecting portion is pressed against the other connecting side by the elasticity of the coil spring in the axial direction. A lens displacing device comprising a second urging means that constitutes one urging means and that presses the rack member against the lead screw by elasticity in a circumferential direction (twisting direction).   The rack member has a rack plate portion that meshes with the lead screw, and one or more screw restricting portions that confront the rack plate portion and restrict the position of the lead screw by sandwiching the lead screw. The lens displacement device according to claim 1.   2. The lens displacement device according to claim 1, wherein the lens includes at least one of or both of a focus lens group constituting an autofocus mechanism and a zoom lens group constituting a zoom mechanism.

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