JPH08298675A - Flange-back distance measuring device for video camera - Google Patents

Abstract

(57) [Summary] [Purpose] Light drive, compact size, and high durability. A cam drive ring 29 and a cam driven ring 30 are formed with a plurality of cam grooves 31 and 32, which are arcuate and face each other, on the same circumference of the opposing surfaces, respectively. The cam follower ring 30 is pressed in parallel to the cam drive ring 29 side by the three compression coil springs 34 with the three cam balls 33 interposed therebetween, and the rotation of the cam drive ring 29 causes the cam ball 33 to come into rolling contact. It is characterized in that the CCD camera 1 is moved in parallel with the cam follower ring 30 in the optical axis direction by a cam action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flange back distance measuring device for a video camera for measuring a flange back distance of an image pickup device when manufacturing, assembling, maintaining, inspecting or repairing the video camera.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS.
An example of a video camera is a CCD camera (usually called a still camera) 1 that can use the same optical lens as a single-lens reflex camera. This kind of CCD camera 1
Like the single-lens reflex camera, the mount ring 3 is attached to the front panel 2a of the camera body 2, and the optical lens 4 is detachably attached to the mount ring 3 by the bayonet method. It can be exchanged.

On the other hand, inside the camera body 2 of the CCD camera 1 of this type, an optical prism 5 and three CCDs 6a of R, G and B, which are solid-state image pickup elements arranged around the optical prism 5, are provided.
3b type image pickup device 7 composed of 6b and 6c
Is built in. The three CCDs 6a, 6b,
6c is arranged on the main optical axis F ₁ of the optical prism 5 and on the upper and lower branched optical axes F ₂ , F ₃ .

A flip-up type mirror for irradiating the optical viewfinder 8 with the light transmitted through the optical lens 4 is provided between the image pickup device 7 and the mount ring 3 inside the camera body 2. A mirror mechanism 9 and a shutter mechanism 10 including a focal plane shutter are arranged.

For this reason, in the main CCD camera 1,
A mirror and shutter assembly 12 incorporating a mirror mechanism 9 and a shutter mechanism 10, and an imaging device 7
And a CCD assembly 13 incorporating the above.
Then, the mount ring 3 is screwed to the front surface of the mirror and shutter assembly 12, and the CCD assembly 1 is attached to the rear surface of the mirror and shutter assembly 12.
3 is fixed with screws using a plurality of screws 14.

When manufacturing, assembling, maintaining, inspecting or repairing the CCD camera 1, a flange is a distance between the lens mount surface 3a of the mount ring 3 and the image pickup surface 6aa of the CCD 6a on the main optical axis F _1. The back distance L is measured by a flange back distance measuring device 17, which will be described later.

When the measured flange-back distance L has an error with respect to the reference value, a flange-back distance adjusting spacer 15 is sandwiched between the mirror / shutter assembly 12 and the CCD assembly 13, and these are inserted. The flange back distance L is adjusted by screwing. In addition, the spacer 15
Are clamped together by being sandwiched between a plurality of screw fastening points by a plurality of screws 14.

A conventional flange back distance measuring device will be described with reference to FIG.

This conventional flange back distance measuring device 1
7, a stand 19 is vertically mounted on a base 18, a cylindrical lens barrel holder 20 is horizontally mounted on the stand 19, and the lens barrel 2 is installed inside the lens barrel holder 20.
1 is attached horizontally.

A test chart glass 22 on which a test chart (not shown) is printed is incorporated inside the tip 21a of the lens barrel 21, and a plurality of optical lenses 23 are provided inside the lens barrel 21. Is built in.

A cylindrical camera holder 24 is arranged on the outer periphery of the rear end 21b of the lens barrel 21, and a mount ring 25 for detachably attaching the CCD camera 1 to the rear end of the camera holder 24. Are mounted coaxially with the optical axis F ₄ of the lens barrel 21.

Then, on the outer circumference of the lens barrel holder 20, between the stand 19 and the camera holder 24, the camera holder 24 is arranged with respect to the lens barrel holder 20 in the optical axis direction of the lens barrel 21 (in the optical axis F ₄₎ . A fine movement mechanism 26 for parallel movement is attached in the direction of arrow a).

When measuring the flange back distance L of the CCD camera 1, first, the mount ring 3 of the CCD camera 1 is detachably attached to the mount ring 25 of the lens barrel holder 20 by the bayonet method.

Then, the rear end 21a of the lens barrel 21 is inserted into the mount ring 3 of the CCD camera 1 so as to have the same axis, and the optical axis F ₄ of the lens barrel 21 is the main optical axis F ₁ of the image pickup device 7. To be matched.

Accordingly, the shutter mechanism 10 of the CCD camera 1 is opened, and the test chart of the lens barrel 21 is taken by the optical lens 23a by the image pickup surface 6aa of the CCD 6a of the image pickup device 7.
In the state of being projected on the camera, the fine movement mechanism 26 performs fine movement adjustment by parallel movement of the camera holder 24 in the direction of the arrow a which is the optical axis direction, and an error value of the flange back distance L with respect to the reference value is magnified (not shown). Etc.

The spacer 15 for flange back adjustment shown in FIG. 8 is replaced with a spacer 15 having a thickness corresponding to the error value of the flange back distance L, and the CCD assembly 13 is attached to the mirror and shutter assembly 12. The screw is stopped and the flange back distance adjustment work is completed.

[0017]

However, the conventional flange-back distance measuring device 17 employs a sliding screw feed screw structure for the fine movement mechanism 26, and the drive is remarkably heavy due to the high load. Further, in order to improve the durability, it is necessary to improve the lubrication of the sliding contact portion, which causes a problem of high cost. Although it is possible to use a ball screw with a rolling contact and a low load for the feed screw structure, the ball screw must be long in the axial direction (referred to as the optical axis direction), which increases the size of the entire device. There is a problem that it will end up.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a flange-back distance measuring device for a video camera which is light in driving, small in size, and high in durability.

[0019]

A flange back distance measuring device for a video camera according to the present invention for achieving the above object includes a video camera having an image pickup device, and a lens barrel for projecting a test chart onto the image pickup device. A lens barrel holder that holds the outer periphery of the lens barrel, a cam drive ring that is rotatably attached to the outer periphery of the lens barrel holder, and a light of the lens barrel that is disposed on the outer periphery of the end of the lens barrel. A cam follower ring that is configured to be translated in the axial direction and to which the video camera is detachably attached by a mount ring, and a facing surface of each of the cam drive ring and the cam follower ring along the same circumference. A plurality of cam grooves formed in a circular arc shape and facing each other, a plurality of cam balls interposed between the plurality of cam grooves, and the cam follower. The ring is obtained and an elastic pushing means for parallel pressed to the cam drive ring.

[0020]

The flange-back distance measuring device for a video camera according to the present invention constructed as described above is provided with a fine movement mechanism for finely moving the video camera in the axial direction of the lens barrel. The drive ring, the cam driven ring that is arranged on the outer periphery of the end of the lens barrel and is translated in the optical axis direction of the lens barrel, and has an arc shape along the same circumference of these facing surfaces, and A plurality of cam grooves formed to face each other, a plurality of cam balls interposed between the plurality of cam grooves, and an elastic pressing means for pressing the cam driven ring in parallel to the cam drive ring side. Since the cam driving ring is rotated, the cam action of the rolling contact by the plurality of cam grooves and the cam balls and the synergistic action of the elastic pressing means together with the cam follower ring are integrated with the video driven ring. It can be fine motion adjusting at low load La in the optical axis direction of the lens barrel.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flange back distance measuring device for a video camera to which the present invention is applied will be described below with reference to FIGS. It should be noted that the same structural parts as those in FIGS. 7 to 9 are designated by the same reference numerals to omit redundant description.

First, as shown in FIGS. 1 to 4, the fine movement mechanism 26 in the flange back distance measuring device 17 of the present invention.
Is arranged on the outer periphery of the lens barrel holder 20 via a cross roller bearing 28 so as to be rotatable, and on the outer periphery of the rear end 21b which is the end of the lens barrel 21, and The cam driven ring 30 that is translated in the direction of the arrow a, which is the optical axis direction, and the facing surfaces 29a and 30a of the cam drive ring 29 and the cam driven ring 30,
A plurality of cams each having an arc shape along the circumference of one circle O ₁ centered on the optical axis F ₄ and facing each other, that is, three cams (six in total), respectively. Groove 31,
32, three cam balls 33 such as steel balls interposed between these three cam grooves 31, 32, and three compressions which are elastic pressing means for pressing the cam driven ring 30 in parallel to the cam drive ring 29 side. It is constituted by a coil spring 34.

The three cam balls 33 are held by the retainer 35 at equal intervals and in a state where each of them can rotate, and the cam grooves 31, 32, the cam ball 33, the compression coil spring 34, and the retainer 35 are used as rollers. A cam mechanism 36 for rolling contact is configured.

The three cam grooves 31, 32 facing each other in the cam mechanism 36 are inclined parallel to the optical axis F ₄ of the lens barrel 21 at a predetermined angle θ.

Inside the three cam grooves 31, 32,
Side surface 20a of the lens barrel holder 20 on the cam follower ring 30 side
3 attached horizontally by press-fitting in 3 places on the circumference of
The three spring mounting shafts 38 penetrate through the three spring mounting holes 39 of the cam driven ring 30. And
Three compression coil springs 34 are inserted into the spring mounting holes 39 on the outer periphery of these spring mounting shafts 38 in a state in which initial compression stress is applied, and are fixed by retaining washers 40.

Also, the side surface 20a of the lens barrel holder 3
Three thrust shafts 41, which are horizontally fixed on the same circumference as the three spring mounting shafts 38 and at three intermediate positions of the three spring mounting shafts 38 by press fitting or the like, are press-fitted into the cam driven ring 30. Is slidably penetrated into a thrust bearing 42 that is horizontally mounted. Therefore, the cam follower ring 30 is supported by these three thrust shafts 41 and thrust bearings 42 and is moved in the optical axis direction (direction of arrow a).
It is supported so that it can be translated.

A camera holder 24 having a mount ring 25 is fixed to the surface of the cam follower ring 30 opposite to the cam drive ring 29 side so as to be coaxial with the lens barrel 21. A scale ring 43, which is a measuring means for measuring the flange back distance L, is fixed to the outer circumference of the cam drive ring 29, and a magnescale 44, which is also a measuring means, is mounted on the stand 19 on the scale holder 4.
5 is mounted horizontally via the cam follower ring 30.
It is pressed by the contacted portion 30b on the outer periphery on the 0a side.

According to the fine movement mechanism 26 of the present invention configured as described above, the mount ring 2 of the camera holder 24 is
5, with the mount ring 3 of the CCD camera 1 which is a video camera detachably attached, the cam drive ring 2
When 9 is rotated in the forward direction (arrow b ₁ direction) and the reverse direction (arrow b ₂ direction), as shown in FIGS. 4A and 4B, the cam follower ring 30 causes the cam follower ring 30 to move to the optical axis. The flange back distance L of the CCD camera 1 is finely adjusted by fine adjustment by parallel movement in the direction (arrow a direction).

The error value with respect to the reference value of the flange back distance L of the CCD camera 1 can be easily measured by measuring means such as the scale ring 43 and the magnescale 44.

At this time, as shown in FIGS. 4A and 4B, the cam mechanism 36 rotates the cam drive ring 29 in the positive direction of the arrow b ₁ to rotate the cam mechanism 36 on the driven side. The phase of the cam groove 31 on the drive side with respect to changes in the direction of arrow b _1, and the cam groove 32 on the drive side causes the cam ball 33 to move.
Is driven. At this time, the roller cam ball 33 with is pushed in the arrow a ₁ direction which is one direction of the optical axis direction while rollers rising in the arrow b ₂ direction by the rotation action of the arrow b ₁ direction with respect to the cam groove 32 of the driven side A cam acting force that pushes the cam groove 32 on the driven side in the direction of arrow a ₁ while rolling, acts,
The cam driven ring 30 is finely adjusted in the arrow a ₁ direction against the compression coil spring 34.

On the contrary, when the cam driving ring 29 is rotated in the opposite direction of the arrow b ₂ , the phase of the driving cam groove 31 with respect to the driven cam groove 32 is indicated by the arrow b _2.
Direction, the cam ball 33 rolls in the direction of arrow b ₁ due to the rotation of the cam ball 33, and the cam acting force acts in the direction of arrow a ₂ , and the cam driven ring 30 follows the arrow a ₂ by the compression coil spring 34. Finely adjusted in the direction.

Therefore, the cam mechanism 36 is driven by the cam action by the rolling contact of the three cam balls 33 and the synergistic action with the three compression coil springs 34, and the rolling contact of the three cam balls 33 is made. Since the load is extremely low, the cam drive ring 29 can be rotationally driven in the directions of the arrows b ₁ and b ₂ very lightly, and the flange back distance L can be measured lightly.

Since the cam action of the rolling contact of the cam ball 33 is very low in friction, the durability is very high and the lubrication is easy, so that the cost can be reduced.

In addition, the cam mechanism 36 is very space-saving, and compared with a feed screw mechanism using a ball screw,
Since the length in the axial direction (which means the optical axis direction) can be made extremely small, the entire flange back distance measuring device 17 can be made small and lightweight.

The cam mechanism 36 includes three cam balls 3
3 are arranged at equal intervals in the circumferential direction, and the cam drive ring 29
On the other hand, since the cam follower ring 30 is supported by these three cam balls 33 at three points, the cam follower ring 30 can be stably translated in the optical axis direction.

Further, since the cam drive ring 29 is rotatably attached to the outer periphery of the lens barrel holder 20 via the cross roller bearing 28, rattling due to the lateral pressure of the cam drive ring 29 occurs at the time of measuring the flange back distance L. Instead, the flange back distance L can always be measured accurately.

Incidentally, FIG. 5 shows three cam grooves 31,
32 and three cam balls 33 are two concentric circles inside and outside O
_The cam balls 33 are arranged at equal intervals along the circumference of ₁ and O ₂ , and a total of six cam balls 33 are formed. This allows
The load can be reduced to 1/2 by doubling the number of rolling contact points of the cam follower ring 30 with respect to the cam drive ring 29, and the maximum rotation angle of the cam drive ring 29 can be reduced to half as shown in FIG. It can be as large as the structure shown in.

Further, FIG. 6 shows three cam grooves 31,
32 and three cam balls 33 are arranged in two stages in the optical axis direction between the cam drive ring 29 and the cam follower ring 30 via a cam intermediate ring 46. This allows
The cam driven ring 3 for the rotation angle of the cam drive ring 29
The moving distance of 0 in the optical axis direction can be doubled.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention.

[0040]

The flange back distance measuring device for a video camera of the present invention constructed as described above has the following effects.

According to a first aspect of the present invention, a cam camera is integrated with a cam follower ring by a cam operation of rolling contact of a plurality of cam grooves and a plurality of cam balls by a rotational operation of a cam drive ring and a synergistic effect of an elastic pressing means. Since the fine movement can be adjusted with a low load in the optical axis direction of the lens barrel, the rotational drive of the cam drive ring can be performed very lightly, and the flange back distance measurement work can be performed lightly. Moreover, the cam mechanism consisting of the cam groove and the cam ball is very space-saving, and the overall size and weight of the flange back distance measuring device can be reduced. Further, the cam mechanism that exerts the cam action by the rolling contact of the cam ball has low friction and thus has extremely high durability and easy lubrication, so that cost reduction can be realized.

According to a second aspect of the present invention, since the cam drive ring is rotatably attached to the outer periphery of the lens barrel holder via a cross roller bearing, rattling due to the side pressure of the cam drive ring can be eliminated, and the flange back distance can be eliminated. Can always be measured accurately.

Since the plurality of cam grooves and the plurality of cam balls facing each other are arranged along the plurality of concentric circles, the load can be significantly reduced while increasing the maximum rotation angle of the cam drive ring. .

According to a fourth aspect of the present invention, the plurality of cam grooves and the plurality of cam balls facing each other are arranged in a plurality of stages in the optical axis direction between the cam driving ring and the cam driven ring via a cam intermediate ring. The moving distance of the cam driven ring with respect to the cam drive ring in the optical axis direction can be increased.

[Brief description of drawings]

FIG. 1 is a schematic side view of the entire apparatus for explaining an embodiment of a flange back distance measuring apparatus for a video camera to which the present invention has been applied.

FIG. 2 is an enlarged cross-sectional side view illustrating a main part of the present invention.

FIG. 3A is an enlarged cross-sectional side view of a thrust bearing portion, and FIG. 3B is a front view of a cam mechanism on the cam drive ring side.

FIG. 4 is a cross-sectional view illustrating a cam action of the cam mechanism due to rolling contact.

FIG. 5 is a front view illustrating a first modified example of the cam mechanism.

FIG. 6 is a schematic cross-sectional view illustrating a second modified example of the cam mechanism.

FIG. 7 is a schematic cross-sectional side view of the entire device for explaining a conventional flange back distance measuring device for a video camera.

FIG. 8 is a sectional side view illustrating a flange back distance of a CCD camera and an assembling structure of an image pickup device.

FIG. 9 is a perspective view of the entire CCD camera.

[Explanation of symbols]

 1 CCD camera (video camera) 2 Camera body 3 Mounting ring 7 Imaging device 15 Flange back distance adjusting spacer 17 Flange back distance measuring device 19 Stand 20 Lens barrel holder 21 Lens barrel 22 Test chart glass 24 Camera holder 25 Mounting ring 26 Fine movement Mechanism 28 Cross roller bearing 29 Cam drive ring 30 Cam driven ring 31 Cam groove 32 Cam groove 33 Cam ball 34 Compression coil spring (elastic pressing means) 35 Retainer 36 Cam mechanism 41 Thrust shaft 42 Thrust bearing 43 Scale ring (measuring means) 44 Magne Scale (measuring means) 46 Cam intermediate ring L Flange back distance

Claims (4)

[Claims] 1. A video camera having an image pickup device, a lens barrel for projecting a test chart onto the image pickup device, a lens barrel holder for holding the outer periphery of the lens barrel, and a rotatably mounted on the outer periphery of the lens barrel holder. Cam drive ring, and a cam that is arranged on the outer periphery of the end of the lens barrel and is configured to be translated in the optical axis direction of the lens barrel, and the video camera is detachably attached by a mount ring. The driven ring, a plurality of cam grooves formed on the respective facing surfaces of the cam drive ring and the cam driven ring in an arc shape along the same circumference, and in a state of facing each other; A video camera including a plurality of cam balls interposed between a plurality of cam grooves and elastic pressing means for pressing the cam driven ring in parallel with the cam drive ring. Mela's flange back distance measuring device. 2. A flange back distance measuring device for a video camera according to claim 1, wherein said cam drive ring is rotatably attached to the outer periphery of said lens barrel holder via a cross roller bearing. 3. A flange back distance measuring device for a video camera according to claim 1, wherein a plurality of cam grooves and a plurality of cam balls facing each other are arranged along a plurality of concentric circles. 4. A plurality of cam grooves and a plurality of cam balls facing each other are arranged in a plurality of steps in the optical axis direction between the cam driving ring and the cam driven ring via a cam intermediate ring. The flange back distance measuring device for a video camera according to claim 1.