JP2006039098A - Lens position adjusting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens position adjusting mechanism capable of surely fixing a lens, and also, preventing a screw from being loosened, with a simple structure. <P>SOLUTION: A screw groove 42 for screwing a self-tap screw 50 is formed on the peripheral surface of a lens frame 22. After rotating the lens frame 22 and positioning the lens frame 22 in a desired focusing position, the self-tap screw 50 is screwed in the screw groove 42 through a positioning hole 48. The self-tap screw 50 is firmly fixed in the screw groove 42. Also, the positioning hole 48 is formed so that the width may be nearly the same as the diameter (dimension t) of the thread part of the self-tap screw 50, then, the rotation of the lens frame 22 is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens position adjusting mechanism, and more particularly to a lens position adjusting mechanism used for a surveillance camera or the like.

In many cases, surveillance cameras, in-vehicle cameras, and the like install a camera at a predetermined position and permanently photograph a subject at a predetermined distance. As a photographic lens used for such a purpose, there is known a lens that can completely fix the focus position so that the focus position does not fluctuate after the focus adjustment. For example, some single focus lenses currently provided include the following lens position adjustment mechanism. The entire lens group constituting the single focus lens is held by one lens frame, and the lens frame is moved back and forth in the optical axis direction with respect to the fixed cylinder (fixed lens barrel) as it rotates. . Therefore, focus adjustment can be performed by rotating the lens frame. On the other hand, the fixed cylinder is provided with a screw hole. After adjusting the focus, a screw is screwed through the screw hole, and the lens frame is fixed at a desired position by pressing the outer periphery of the lens frame with the screw tip. Be able to. Therefore, the focus position can be fixed by fixing the lens frame at the focus adjusted position (see, for example, Patent Document 1).
JP 2003-233102 A

  However, in such a lens position adjusting mechanism, the lens frame is tilted due to a structure in which the lens frame is pressed (pressed) in a direction substantially perpendicular to the optical axis direction by a screw, and the lens optical axis and the central axis of the fixed cylinder are Eccentric. Therefore, there is a problem that the lens fixing work after the focus adjustment becomes complicated. Further, there has been a problem that the optical performance cannot be maintained due to the above-mentioned eccentricity or defocusing after fixing due to looseness of the lens frame caused by loosening of screws.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lens position adjusting mechanism that can securely fix a lens with a simple structure and can also prevent a screw from loosening.

  In order to achieve the above object, the present invention adjusts the position of the lens group by moving a predetermined lens group back and forth in the optical axis direction with respect to a fixed cylinder, and fixes the lens group at the adjusted position. In the position adjustment mechanism, a lens frame that holds the lens group, a moving mechanism that moves the lens frame back and forth in the optical axis direction with respect to the fixed cylinder by rotation of the lens frame, and a circumferential direction of the lens frame A formed groove, and a positioning hole formed in the fixed cylinder so as to face a part of the groove of the lens frame when the lens frame is located within a predetermined movement range with respect to the optical axis direction; A rotation restricting means for restricting the rotation of the lens frame by inserting the positioning hole to engage the engaging member with the groove and engaging the engaging member with the positioning hole; It is characterized by

  According to the present invention, when the engaging member is fitted into the groove through the positioning hole, the engaging member is engaged with the groove and at the same time, the engaging member is locked into the positioning hole. Accordingly, the lens frame (lens) and the fixed cylinder can be reliably fixed by the groove and the engaging member. Here, as the engaging member, for example, the elastic member itself has rubber-like elastic characteristics, and the size of the insertion portion is slightly larger than the width of the groove or the positioning hole, and is deformed when fitted into the groove or the positioning hole. And those that are firmly fixed to the grooves and positioning holes, and those that are driven into the grooves and positioning holes in a wedge shape. In order to firmly fix the lens frame and the fixed cylinder, for example, a self-tapping screw that forms a tap in the groove or the positioning hole may be used. Accordingly, the lens frame and the fixed cylinder can be fixed with a simple structure, and for example, the manufacturing cost can be reduced.

  The present invention described in claim 2 is characterized in that the engaging member is a self-tapping screw for forming a tap in the groove. Since the self-tapping screw (tapping screw) is used, a tap is formed in the groove of the lens frame, the self-tapping screw can be firmly fixed to the lens frame, and the lens frame and the fixing tube can be securely fixed. In addition, the lens frame can be fixed to the fixed cylinder without pressurizing the lens frame with the self-tap screw, and the eccentricity of the lens optical axis due to the tilting of the lens can be prevented. Since the tap is formed in the groove, the self-tapping screw can be prevented from loosening.

  Here, the “self-tapping screw” in this specification includes, for example, a so-called tapping screw or a screw. In other words, tighten the screw itself with the screw itself in a hole (preparation hole, boss) that is smaller than the outer diameter of the screw and does not have a thread, or has an auxiliary thread for forming the thread. A general mechanism similar to a screw with a self-tapping function is widely meant.

  According to the third aspect of the present invention, since the positioning hole is formed by a long hole along the optical axis direction, the lens frame is independent of the position of the lens frame moving along the optical axis direction. Can be fixed to a fixed cylinder. The effective length in the longitudinal direction of the positioning hole is set to a length that allows the engaging member to be fitted into the groove even if the lens frame is moved by focus adjustment. Further, it is desirable that the width of the positioning hole is formed to be approximately the same as the outer diameter of the screw. Thereby, the play of the rotation direction of a lens frame can be controlled efficiently.

  According to the fourth aspect of the present invention, the moving mechanism can rotate the lens frame by engaging the cam pin protruding from one of the lens frame and the fixed cylinder and the cam groove formed at the other. Along with the movement, the lens frame is moved back and forth in the optical axis direction with respect to the fixed cylinder. In other words, the play in the optical axis direction of the lens frame can be eliminated by the cam pin and the cam groove, and the play in the rotation direction of the lens frame can be eliminated by the engaging member. As a result, the lens frame can be reliably positioned and fixed to the fixed cylinder.

  According to the fifth aspect of the present invention, the moving mechanism moves the lens frame along with the rotation of the lens frame by screwing the screw part formed on the lens frame and the screw part formed on the fixed cylinder. Move back and forth in the optical axis direction with respect to the fixed cylinder. Here, as an example of the screw portion formed on the lens frame and the screw portion formed on the fixed cylinder, a helicoid screw is preferably used in order to eliminate backlash in the optical axis direction of the lens frame. The play in the optical axis direction of the lens frame can be eliminated by the helicoid screw, and the play in the rotation direction of the lens frame can be eliminated by the engaging member. Thereby, the lens frame can be reliably positioned and fixed to the fixed cylinder.

  According to the present invention, since the lens frame can be fixed without being pressed down, the eccentricity of the lens optical axis can be prevented.

  Hereinafter, a preferred embodiment of a lens position adjusting mechanism according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a side view schematically showing a lens barrel 12 of a surveillance camera 10 to which a lens position adjusting mechanism according to the present invention is applied. As shown in the figure, the lens barrel 12 includes a substrate 14, a CCD (imaging device) 16, a fixed barrel (fixed barrel) 18, a lens frame 22 including a lens (group) 20, and a lens position adjustment. The mechanism 30 is configured. In addition, the lens 20 shall show the lens group which comprises the single focus lens with a fixed focal distance, for example.

  The substrate 14 is attached to a housing 26 for attaching the monitoring camera 10 to the wall surface 24 via screws (not shown), and a CCD 16 is attached to the substrate 14 via a bracket 28.

  The fixed lens barrel 18 is positioned on the substrate 14 by a positioning boss 27, and a base portion thereof is fixed by a screw (not shown).

  A cover glass 32 for protecting the CCD 16 is attached to the light receiving surface side of the CCD 16 (that is, the left side of the CCD 16 in FIG. 1). An IR cut filter (or low-pass filter) 34 supported by the fixed barrel 18 is disposed on the front surface of the cover glass 32.

  Reference numeral 36 denotes an elastic member for fixing the filter 34 with respect to the optical axis L (the one-dot chain line in FIG. 1). The optical axis L indicates an optical path through which the subject light incident in the lens barrel 12 passes. The subject light transmitted through the lens 20, the IR cut filter 34, the cover glass 32, etc. reaches the CCD 16, and the CCD 16 An image of the subject is formed on the light receiving surface.

  Although not shown in the drawing, it is assumed that other existing devices necessary for photographing, such as a diaphragm for adjusting the amount of light, are appropriately arranged in the lens barrel 12.

  Next, the lens position adjusting mechanism 30 will be described. The lens frame 22 is rotatably held by the fixed barrel 18 and rotates about the optical axis L. The lens frame 22 is formed with a lead (cam) groove 40 and a screwing groove 42 on its peripheral surface. A cam pin 44 protrudes from the inner peripheral surface of the fixed barrel 18, and the cam pin 44 engages with the lead groove 40. As will be described later, a self-tapping screw 50 is screwed into the screwing groove 42.

  FIG. 2 is a schematic diagram showing the positions of the lead groove 40 and the screwing groove 42 in an expanded manner with respect to the outer periphery of the lens frame 22. The lead groove 40 is formed to be slightly inclined with respect to the screwing groove 42 as shown in FIG. When the cam pin 44 is engaged with the lead groove 40, the lens frame 22 is guided to the cam pin 44. That is, when the lens frame 22 is rotated (arrow A in FIG. 2), the intersection position of the lead groove 40 and the cam pin 44 is displaced along the lead groove 40, and the lens frame 22 is along the optical axis direction according to the displacement. A moving mechanism for moving (arrow B in FIG. 2) is configured.

  A positioning hole 48 into which a self-tapping screw 50 is inserted is formed in the fixed barrel 18 (see FIG. 1). The positioning hole 48 is formed as a long hole along the optical axis direction, and the effective length in the longitudinal direction is set longer than the diameter (dimension t) of the screw portion of the self-tapping screw 50. Specifically, the long hole is set to a length that faces a part of the screwing groove 42 within a range in which the lens frame 22 is movable in the optical axis direction. Thereby, the self-tapping screw 50 is screwed into the screwing groove 42 from the positioning hole 48 regardless of the position of the lens frame 22.

  On the other hand, the width dimension of the positioning hole 48 is formed to be approximately the same as the diameter (dimension t) of the screw portion so that the backlash between the self-tapping screw 50 and the positioning hole 48 is minimized when the self-tapping screw 50 is inserted.

  Reference numeral 23 denotes a notch for assembly for passing the cam pin 44 of the fixed lens barrel 18 to the lead groove 40 when the lens frame 22 is inserted into the fixed lens barrel 18.

  As shown in FIG. 1, such a lens barrel 12 is covered with a hemispherical cover 60 made of acrylic or polycarbonate having high transparency, for example. A screw part 62 is formed on the rear side of the hemispherical cover 60, and the hemispherical cover 60 is supported by the housing 26 via the screw part 62. It is assumed that the CCD 16 is connected to a circuit (not shown) disposed outside the monitoring camera 10 and the like.

  The operation of the lens position adjusting mechanism of the present invention will be described below.

  First, focus (focus) adjustment will be described. In FIG. 1, the hemispherical cover 60 is first removed, and the lens frame 22 is rotated to position the lens frame 22 at a desired focus adjustment position. By the feeding action of the lead groove 40 of the lens frame 22 and the cam pin 44 of the fixed lens barrel 18, the lens frame 22 is moved back and forth along the optical axis L direction, and the focus adjustment can be performed. The focus adjustment may be adjusted by separately displaying an image captured by the operator via the CCD 16 on a monitor or the like, or by using an automatic focus adjustment device (not shown) or the like.

  Next, the self-tapping screw 50 is screwed into the screwing groove 42 through the positioning hole 48 to fix the position of the lens frame 22. In FIG. 2, a screw thread 42 </ b> A is formed in the screwing groove 42 by a self-tapping screw 50, and the self-tapping screw 50 is firmly fixed to the lens frame 22. At this time, a load is applied to the screwing groove 42 so as to widen the screwing groove 42 by the self-tapping screw 50, but this is not impossible in the direction in which the lens frame 22 is pressurized. Thereby, the lens frame 22 is not pressed in the direction substantially perpendicular to the optical axis L (the direction perpendicular to the paper surface in FIG. 2), and the lens optical axis can be prevented from being eccentric due to the tilting of the lens.

  Further, since the width dimension of the positioning hole 48 is formed to be approximately the same as the diameter (dimension t) of the thread portion of the self-tapping screw 50, the rotation of the lens frame 22 indicated by the arrow A in FIG. Since the movement of the lens frame 22 in the optical axis direction indicated by the arrow B in FIG. 2 is also restricted by the cam pin 44 and the lead groove 40, the lens frame 22 and the fixed lens barrel 18 are completely connected by screwing in the self-tapping screw 50. Fixed.

  After the focus adjustment and the lens frame 22 are fixed in this way, the hemispherical cover 60 shown in FIG. 1 is attached to the housing 26, and the focus adjustment / fixing operation is completed.

  Here, instead of the moving mechanism of the lens frame 22 by the lead groove 40 and the cam pin 44 shown in FIG. 1, a helicoid screw is attached to the lens frame 72 and the fixed lens barrel 74 as shown in the lens barrel 70 shown in FIG. A lens mount mechanism according to 76 may be applied.

  That is, a female helicoid screw 78 is formed on the inner peripheral portion of the fixed barrel 74, and a male helicoid screw 80 that is screwed with the female helicoid screw 78 is formed on the outer peripheral portion of the lens frame 72. When the lens frame 72 is rotated, the lens frame 72 is moved back and forth along the optical axis L direction by the feeding action of the female helicoid screw 78 and the male helicoid screw 80, and the focus adjustment can be performed.

  The lens frame 72 is formed with a screwing groove 82 having the same configuration as the above-described screwing groove 42 (see FIG. 2) on the peripheral surface thereof. After the focus adjustment by the lens frame 72, the screwing groove 82 includes A self-tapping screw 50 is screwed through a positioning hole 84 formed in the fixed lens barrel 74. The positioning hole 84 has the same configuration as the positioning hole 48 described above.

  Thus, according to the lens position adjusting mechanism according to the present embodiment, the lens frame and the fixed barrel can be fixed with an easy structure. Further, since the self-tapping screw is used, the lens frame can be fixed to the fixed cylinder without pressing the lens frame. Moreover, the self-tapping screw can prevent the screw from loosening.

  The configuration of the lens position adjusting mechanism shown in the embodiment as described above is not limited to the above embodiment. For example, instead of the self-tapping screw, a rubber-like pin having a rubber-like elastic characteristic itself and having a size of a fitting portion slightly larger than the width of the groove may be used. If the pin is inserted into the groove, the pin and the groove are firmly fixed, and the same effect as the present invention can be obtained.

  Moreover, although the example which applied the lens position adjustment mechanism which concerns on this invention to the surveillance camera was shown, it is not limited to this, For example, this invention is applicable also to a vehicle-mounted camera, an underwater camera, etc.

  In the above embodiment, the case where the lens position adjusting mechanism according to the present invention is applied as a mechanism for adjusting and fixing the position of the lens group 20 constituting the single focus lens has been described. The present invention can be applied to various types of lenses (not limited to photographing lenses) by adjusting and fixing the position of a part or the whole lens group constituting the lens.

The side view which shows the surveillance camera to which the lens position adjustment mechanism which concerns on embodiment of this invention was applied. Schematic diagram showing details of the lens barrel according to the embodiment of the present invention The side view which shows another embodiment of the surveillance camera to which the lens position adjustment mechanism which concerns on embodiment of this invention was applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Surveillance camera, 12, 70 ... Lens barrel, 18, 74 ... Fixed barrel, 20 ... Lens, 22, 72 ... Lens frame, 30 ... Lens position adjustment mechanism, 40 ... Lead groove, 44 ... Cam pin, 48, 84 ... Positioning hole, 50 ... Self-tapping screw, 76 ... Helicoid screw, 78 ... Female helicoid screw, 80 ... Male helicoid screw, L ... Optical axis, t ... Diameter of screw part of self-tapping screw

Claims (5)

In a lens position adjustment mechanism for adjusting a position of the lens group by moving a predetermined lens group back and forth in the optical axis direction with respect to a fixed cylinder, and fixing the lens group at the adjusted position,
A lens frame for holding the lens group;
A moving mechanism for moving the lens frame back and forth in the optical axis direction with respect to the fixed cylinder by rotating the lens frame;
Grooves formed in the circumferential direction of the lens frame;
A positioning hole formed in the fixed cylinder so as to face a part of the groove of the lens frame when the lens frame is located within a predetermined movement range with respect to the optical axis direction;
A rotation restricting means for restricting the rotation of the lens frame by inserting the positioning hole to engage the engaging member with the groove and engaging the engaging member with the positioning hole; A lens position adjusting mechanism characterized by that.   The lens position adjusting mechanism according to claim 1, wherein the engaging member is a self-tapping screw that forms a tap in the groove.   The lens positioning mechanism according to claim 1 or 2, wherein the positioning hole is formed as a long hole along the optical axis direction.   The moving mechanism fixes the lens frame as the lens frame rotates by engaging a cam pin protruding from one of the lens frame and the fixed cylinder and a cam groove formed on the other. 4. The lens position adjusting mechanism according to claim 1, wherein the lens position adjusting mechanism is moved back and forth in the optical axis direction with respect to the tube.   The moving mechanism is configured such that when the lens frame is rotated, the lens frame is moved with respect to the fixed tube by an optical axis by screwing a screw portion formed on the lens frame and a screw portion formed on the fixed tube. 4. The lens position adjusting mechanism according to claim 1, wherein the lens position adjusting mechanism is moved back and forth in a direction.

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