JP3593538B2 - Helicoid mechanism of lens for CCTV camera - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-stripe helicoid structure used in, for example, a focus mechanism and a zoom mechanism of a lens for a CCTV camera .
[0002]
[Prior art]
A multi-stripe helicoid is used for a focus and zoom mechanism of a lens for a CCTV (closed circuit television) camera used as a surveillance camera or the like. The reciprocating movement of the helicoid of the lens for the CCTV camera in the optical axis direction is performed by a cam mechanism formed by a screw provided in a lens barrel serving as a male screw supporting the lens system and an opening provided in the lens barrel serving as a female screw. Done. The optical system of a lens for a CCTV camera is small, the number of helicoids is large, and the cylindrical outer wall of a lens barrel that supports the lens system is covered with fine-pitch threads. Therefore, the screw and the opening for the cam mechanism must be arranged so as to avoid the lens barrel provided with the screw, which not only complicates the structure but also hinders miniaturization. Also, since a large number of threads are formed on the outer peripheral wall of the lens barrel near the center of the lens system, screws cannot be provided near the center of the lens system, and the cam mechanism is separated from the center of the lens system. Must be provided at the site. Therefore, more stable movement of the lens system in the direction of the optical axis is also inhibited.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a simple and compact helicoid lens barrel for a CCTV camera lens .
[0004]
[Means for Solving the Problems]
A helicoid mechanism of a CCTV camera lens according to the present invention includes a helicoid male member having first and second spiral ridges having the same lead on a cylindrical outer wall, and a helicoid male member inserted through the cylindrical inner wall. A helicoid female member having a first concave thread engaged with the first convex thread and a second concave thread engaged with the second convex thread, wherein the width of the first convex thread is the second convex thread. Is wider than the width of the ridge.
[0005]
Preferably, in order to relatively displace the positional relationship between the helicoid male member and the helicoid female member along the cylindrical axis, at least one of the first ridges is provided with a screw, and the corresponding first concave is provided. The strip has an opening along the strip, and the screw and the opening form a cam mechanism. Thus, the cam mechanism is provided at the same location as the helicoid, the helicoid lens barrel can be reduced in size, and the configuration is simplified. Further, the point of action of the force acting on the helicoid male member by the cam mechanism can be easily set near the center of the helicoid male member.
[0006]
Further, by making the width of the first ridge an odd multiple of the width of the second ridge, the formation of the ridge becomes easy. That is, in the step of engraving strips having the same pitch, by not engraving some of the strips, such first and second convex strips can be obtained.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a view schematically showing a lens barrel of a CCTV camera lens according to the present embodiment. The upper half of the figure schematically shows a cross section of the lens barrel, and the lower half schematically shows the appearance.
[0008]
In the lens barrel body 10, a focus lens group A, an iris 11, and a zoom lens group B are arranged in this order from the left along the optical axis PP. The lens group A is held by a focus lens barrel 12, and the lens group B is held by a zoom lens barrel (helicoid male member) 13. The focus lens barrel 12, the iris 11, and the zoom lens barrel 13 are held by a support barrel (helicoid female member) 14, and the support barrel 14 is attached to the barrel main body 10 by a support member (not shown). Fixed.
[0009]
The focus lens barrel 12 is engaged with a focus ring 16 via a screw 15 to form a cam structure. That is, by rotating the focus ring 16 around the optical axis PP, the focus lens barrel 12 is translated in the optical axis direction. A large number of spiral grooves (concave stripes) having the same lead are formed on the outer peripheral portion (cylindrical outer wall) 13 a of the zoom lens barrel 13, and a multi-threaded screw is formed. A groove is formed in the cylindrical inner wall portion 14a of the support lens barrel portion 14 to be screwed with the multi-threaded screw of the cylindrical outer peripheral portion 13a. Thus, the supporting lens barrel 14 and the zoom lens barrel 13 form a helicoid structure. That is, the zoom lens barrel 13 can move along the optical axis PP by being rotated around the optical axis PP.
[0010]
The zoom lens barrel 13 is formed with a tapped hole 13b, into which a screw 17 is screwed. An opening 14b is formed in the supporting barrel 14 along the spiral groove of the cylindrical inner wall 14a, and the screw 17 penetrates the opening and reaches the outer periphery of the supporting barrel 14 to form a cam mechanism. That is, the screw 17 is movable along the opening 14b along the spiral groove of the support barrel 14, and when the screw 17 is moved along the opening 14b, the zoom lens barrel 13 rotates around the optical axis PP. It moves in the direction of the optical axis while rotating.
[0011]
One end of a connecting member 19 is fixed to the zoom ring 18 with a screw 20, and the other end of the connecting member 19 is engaged with a head of a screw 17 protruding outside the support barrel 14. The connecting member 19 rotates around the optical axis PP with the rotation of the zoom ring 18. At this time, the screw 17 is rotated around the optical axis PP along the opening 14b and moves in the optical axis direction.
[0012]
FIG. 2 is a perspective view showing the zoom lens barrel 13 and the support barrel 14 before assembly.
The straight line PP is the optical axis. As described above, the outer peripheral portion 13a of the zoom lens barrel 13 has a number of spiral grooves. The supporting lens barrel 14 includes a cylindrical part 14A having a large diameter and in which the focus lens group A is provided, and a cylindrical part 14B having a small diameter and a helicoid structure with the zoom lens barrel 13. On the inner wall 14a of the cylindrical portion 14B, a helical thread that is screwed with the above-described groove formed on the zoom lens barrel 13 is formed. An opening 14b is formed in one spiral strip of the cylindrical portion 14B along the strip, and engages with a screw 17 screwed into the bore 13b to form a cam mechanism.
[0013]
FIG. 3 is a developed view of a cylindrical surface (cylindrical portions 13a and 14a) of the conventional CCTV camera in which spiral grooves of the zoom lens barrel 13 and the support barrel 14 are formed. In the developed view, a number of spiral grooves (concave stripes) formed on the cylindrical surface are represented by a number of parallel straight lines. FIG. 4 shows a part of a cross section taken along a straight line AA in FIG. 3. The straight line AA is a straight line perpendicular to each groove (parallel line) shown in the developed view of FIG. FIG. 4 is a cross-sectional view of the developed view of FIG. 3, so that the zoom lens barrel 13 and the support barrel 14 are also represented as flat plates for convenience. Since the zoom lens barrel 13 and the supporting barrel 14 used in the CCTV camera are generally small in size and the thickness of each barrel is thin, a large spiral groove or thread cannot be provided in each barrel. . That is, as shown in the development of FIG. 3, it is necessary to use helicoids having extremely high pitches for each lens barrel. Therefore, the width of the thread (convex) 31 or the groove (concave) 30 formed in the zoom lens barrel 13 and the support barrel 14 is generally smaller than the diameter of the bit 17. Conventionally, grooves are formed on the entire outer periphery of the zoom lens barrel 13 at a constant fine pitch, and most of the zoom lens barrel 13 is covered with the fine pitch grooves. Accordingly, it is not possible to provide the screw 17 on the cylindrical outer peripheral portion 13a in which the fine groove is formed by the helicoid structure used in the conventional CCTV camera, and it is necessary to separately provide a structure for the cam mechanism in each of the lens barrel portions 13 and 14. I had to.
[0014]
FIG. 5 is a diagram showing a cross section of the helicoid structure of the present embodiment in comparison with a cross section of a conventional helicoid structure. As in FIG. 4, the lens barrel portions 13 and 14 are conveniently represented by flat plates. ing. Further, in FIG. 5, in order to make it easy to see the difference between the grooves formed in the lens barrels 13 and 14, the lens barrels 13 and 14 are drawn slightly apart from the state in which the projections and depressions mesh with each other.
[0015]
In the present embodiment, the groove (second concave streak) 30 conventionally formed regularly at the same pitch is not engraved on the zoom lens barrel portion 13 side by one streak (dashed line portion 35), and the support barrel is not provided. On the part 14 side, a part (broken line part 36) left as the conventional screw thread (second ridge) 31 is cut off. That is, a convex ridge (first convex ridge) 41 having a width three times as large as the convex ridge 31 is formed in the zoom lens barrel 13, and the concave ridge 30 is formed in the support barrel 14. A concave portion (first concave portion) 40 having a triple width is formed.
[0016]
FIG. 6 is a cross-sectional view showing a state in which a tapped perforated hole 13b for screwing the screw 17 is provided in the protruding portion 41 of the zoom lens barrel 13 shown in FIG. A hole 13b is formed in the ridge 41, and a screw 51 is formed on the inner peripheral surface of the hole 13b. The width of the ridge 41 is large enough to perform tapping for the screw 17 (not shown), and the thickness is large, so that stable tapping is possible. In addition, an opening 14b is provided in the concave ridge portion 40 of the support lens barrel portion 14 along a spiral concave ridge portion 40 for forming a screw mechanism and a cam mechanism screwed into the perforated hole 13b.
[0017]
As described above, according to the present embodiment, the helicoid male member is not formed by engraving one of the spiral grooves regularly formed at the same pitch on the outer peripheral wall of the zoom lens barrel corresponding to the helicoid male member. A wide ridge is formed on the member, and one of the helical ridges regularly formed at the same pitch on the inner peripheral wall of the supporting barrel corresponding to the helicoid female member is scraped off, so that the helicoid female member has A wide ridge that is screwed with the wide ridge is formed. Accordingly, tapping can be performed on a wide ridge, and a screw required for the cam mechanism can be provided at a portion where the helicoid mechanism is provided. That is, the cam mechanism and the helicoid mechanism can be integrally formed, and a simple and small helicoid lens barrel can be obtained.
[0018]
Further, since the cam mechanism can be provided near the center of the zoom lens barrel supporting the zoom lens group, a stable zooming operation in the zoom lens barrel can be obtained.
[0019]
Further, since the wide convex ridge is screwed only with the corresponding wide concave ridge, the position at which the zoom lens barrel and the support barrel can be screwed is one in the case of the present embodiment, Positioning during assembly is facilitated.
[0020]
In the present embodiment, the wide ridge is three times as wide as the other ridges. However, the width is not limited to this, and for example, the width is five times the width without forming two spiral grooves. May be provided.
[0021]
In the present embodiment, only the helicoid lens barrel for the zoom lens has been described, but a helicoid lens barrel for the focus lens may be used.
[0022]
【The invention's effect】
As described above, according to the present invention, a simple and compact helicoid lens barrel for a CCTV camera lens can be obtained.
[Brief description of the drawings]
FIG. 1 is a view schematically showing a cross section and an appearance of a lens barrel of a lens for a CCTV camera according to the present invention.
FIG. 2 is a perspective view of a zoom lens barrel 13 and a support lens barrel 14.
FIG. 3 is a development view of a helicoid used in a conventional lens for a CCTV camera .
FIG. 4 is a diagram showing a part of a cross section taken along line AA in FIG. 3;
FIG. 5 is a view showing a cross section of the helicoid of the present embodiment corresponding to FIG. 4;
FIG. 6 is a diagram when tapping is provided on the convex portion 41 and a groove for a cam mechanism is provided on the concave portion 40 in FIG. 5;
[Explanation of symbols]
13 Zoom lens barrel 13a Cylindrical outer wall 14 Supporting barrel 14a Cylindrical inner wall 30 Recess (groove)
31 ridges (threads)
40 concave streak 41 convex streak

Claims (2)

One helical first ridge is provided, and a plurality of second ridges having the same lead as the first ridge are fixed on the entire outer periphery of the cylindrical outer wall except for the first ridge. A helicoid male member provided at a pitch of: a first concave thread that is inserted through the helicoid male member and screwed into the cylindrical inner wall with the first convex strip, and a second concave strip that is screwed with the second convex strip A helicoid female member having two concave stripes;
The width of the first ridge is wider than the width of the second ridge, in order to relatively displace the positional relationship between the helicoid male member and the helicoid female member along a cylindrical axis, with bis is provided on the first projection strip, an opening is provided along the strip to the corresponding said first concave, the bis and the opening and characterized as the CCTV camera lens that forms a cam mechanism Helicoid mechanism. The helicoid mechanism according to claim 1, wherein the width of the first ridge is an odd multiple of the width of the second ridge.

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