JP3298349B2 - Drive device and photographing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for moving a movable lens holding member of a zoom system or a focusing system in the direction of an optical axis in an object such as a video camera and other photographing devices, and a photographing device.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional driving device. In FIG. 7, reference numeral 1 denotes a lens held by a movable ring 2, and 3 denotes a lens formed on the movable ring 2 in parallel with the optical axis XX of the lens 1. And a guide bar 7 for inserting fitting holes 4 and 5 formed at both ends of a sleeve 3 arranged in parallel with the optical axis in a lens barrel to be assembled to a photographing apparatus main body (not shown). Is a screw shaft as a drive shaft arranged in parallel with the guide bar 6, and 8 is a rack or carriage as a driven member mounted between the connecting portions 9, 9 formed integrally with the sleeve 3. In the illustrated example, the rack is The screw shaft 7 is screwed. Reference numeral 10 denotes an optical principal point of the lens 1, and M denotes a motor as a drive source for driving the screw shaft 7 directly or via a gear or the like.

Next, the operation of the above conventional example will be described. When the motor M is operated and the screw shaft 7 is driven, a driving force in the optical axis direction is applied to the sleeve 3 via the rack 8 and the connecting portions 9 and 9. Therefore, the movable ring 2 moves forward and backward in the optical axis direction.

[0004]

However, in the above-mentioned conventional example, the connecting portions 9, 9 of the rack 8 are provided near the center of gravity of the movable ring 2 in order to obtain a smooth operation. In such a case, the movable ring 2 itself delicately vibrates via the rack 8 in conjunction with the vibration caused by the rotation of the screw shaft 7, causing a continuous image blur phenomenon that is unsightly on the photographing screen. There was a point.

[0005] This image blur phenomenon occurs when the movable ring 2 is displaced in the radial direction by the play of the fitting between the screw shaft 7 and the fitting holes 4 and 5 of the sleeve 3. For example, Japanese Unexamined Utility Model Publication No. 5-90418 discloses a conventional example in which the above-described fitting play is performed to prevent image blur.

FIG. 8 is a longitudinal sectional view showing a conventional driving device provided with this urging means, and FIG. 9 is a perspective view of a part thereof.
The same parts as those in the conventional example of FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted. 8 and 9, reference numerals 21a and 21b denote lenses 1 near the fitting holes 4 and 5 at both ends of the sleeve.
Is a biasing means such as a magnet attached to the sleeve position on the opposite side of the sleeve shaft. According to this conventional example, the play of fitting between the screw shaft 7 and the fitting holes 4 and 5 of the sleeve 3 can be reduced, but the cost is increased because a plurality of urging means 21a and 21b are required. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the conventional example, and has as its object to provide a driving device with less image blur phenomenon. It is another object of the present invention to provide a driving device that has a small image blur phenomenon with a simple and inexpensive configuration using a small amount of urging means even if the sleeve length is short.

Another object of the present invention is to provide a photographing apparatus provided with the above-mentioned driving device for moving the lens holding member forward and backward in the optical axis direction.

[0009]

According to a first aspect of the present invention, there is provided a driving device which has a sleeve which holds a lens and has fitting holes formed at both ends for fitting into guide bars arranged parallel to the optical axis. A moving ring, a driving shaft that is arranged in parallel with the guide bar and transmits a driving force in the optical axis direction to a driven member provided on the moving ring, and a driving device that has a driving source that drives the driving shaft; The optical principal point of the lens is located at a position near the optical axis in the radial direction near the one end side fitting hole of the sleeve, and the position of the center of gravity of the moving ring holding the lens is substantially the same as the position of the optical principal point. The lens is attached to the moving ring so as to coincide with each other, and the driven member is attached to the sleeve in the vicinity of the other end side fitting hole of the sleeve, so that the lens moves to the fitting hole 4 side of the sleeve 3. Ring 2 Weight consuming, fitting play a steady state of the hole surface and the guide bar 6 in the sleeve fitting holes 4, are also always energized biased by its own weight in any of the driving state, and has a stable state. As a result, it is possible to reduce a continuous image blur phenomenon that is unsightly on the photographing screen.

According to a second aspect of the present invention, in the driving device, in the vicinity of the fitting hole on one end side of the sleeve, an urging force is added to the weight of the lens, and the surface of the fitting hole on the one end side and the guide bar. Is provided on the sleeve, so that the image blur phenomenon due to the fitting backlash can be reduced more reliably by using a small number of members.

According to a third aspect of the present invention, there is provided the photographing apparatus according to the first or second aspect for moving the lens holding member forward or backward in the optical axis direction. Image blur phenomenon can be reduced.

[0012]

【Example】

First Embodiment FIG. 1 is a longitudinal sectional view of a driving device according to a first embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a front view of FIG. Reference numeral 1 denotes a lens held by the moving ring 2, 3 denotes a sleeve formed on the moving ring 2 in parallel with the optical axis, and 6 denotes a sleeve which is inserted into fitting holes 4 and 5 at front and rear ends of the sleeve 3 so as to be parallel to the optical axis. An arranged guide bar, 7 is a screw shaft arranged in parallel with the guide bar 6, and 8 is a rack or carriage as a driven member mounted between the connecting portions 9, 9 formed on the sleeve 3, and is an illustrated example. Is screwed into the screw shaft 7 with the rack. Reference numeral 10 denotes an optical principal point of the lens 1, and M denotes a motor as a drive source for driving the screw shaft 7 directly or via a gear or the like. Are identical.

In this embodiment, the lens 1 is mounted on the movable ring 2 so that the optical principal point 10 is located on the optical axis in the radial direction near the one end side fitting hole 4 of the sleeve 3. The rack 8 is attached to the sleeve 3 in the vicinity of the other end side fitting hole 5 of the sleeve 3.

Next, the operation will be described. When the motor M is operated and the screw shaft 7 is driven, a driving force in the optical axis direction is applied to the sleeve 3 via the rack 8 and the connecting portions 9 and 9. Therefore, the movable ring 2 moves forward and backward in the optical axis direction.
In this case, in the configuration of the present embodiment, since the position of the center of gravity of the moving ring 2 is substantially determined by the moving lens 1 having a large specific gravity, the position of the center of gravity substantially coincides with the position of the optical principal point 10.

As a result, as shown in FIG.
The entire weight of the movable ring 2 is applied to the fitting hole 4 side, and the play between the hole surface of the sleeve fitting hole 4 and the guide bar 6 is in a steady state.
Even in the driving state, it is constantly biased by its own weight and is in a stable state. For this reason, even if the sleeve fitting hole 5 side vibrates in the radial direction by the play of the fitting between the guide bar 7 and the sleeve fitting hole due to the deflection of the screw shaft 7, the sleeve fitting hole 4 side does It is stable by its own weight,
The screw shaft 7 is rotated by the vibration about the sleeve fitting hole 4 side. That is, the sleeve fitting hole 5 vibrates in the range of the angle θ about the sleeve fitting hole 4 as the center of rotation due to the play of the fitting.

As a result, the optical principal point 10 of the integrally formed lens 1 also oscillates within the range of the angle θ. 4, the displacement ΔR in the radial direction of the optical axis is very small compared to the displacement ΔS in the optical axis direction even when the angle θ changes.

If the rack 8 is arranged at an intermediate position in the optical axis direction XX of the sleeve 3 as in the conventional example shown in FIG. 7, the displacement of the angle .theta. Compared with this embodiment, the displacement ΔS in the optical axis direction is the present embodiment ≧ conventional example, but the radial displacement is this embodiment ≦ conventional example.

Since the radial displacement is a cause of the image shaking phenomenon, the farther the mounting side of the rack 8 is away from the side of the sleeve fitting hole 4 which is the center of rotation, the more the optical principal point becomes at the same angle θ. The radial displacement of No. 10 becomes large, and the amount of occurrence of image shaking becomes very large.

Although the displacement of the optical principal point 10 in the thrust direction in the embodiment is large, in order to provide a smooth operation, A (the distance from the optical axis XX to the sleeve fitting hole) is required. ≦ B (the distance between the sleeve fitting holes, ie, the length of the sleeve), the displacement ΔS of the optical principal point 10 in the thrust direction in the sleeve fitting hole 5 and the guide bar 6
Can be reduced to the extent of the play of fitting. This displacement is 1
Since the displacement is about 0 μm or less, the displacement is sufficiently within the allowable depth of focus for recognizing out-of-focus, and has no adverse effect on the photographing screen.

Second Embodiment FIG. 5 is a longitudinal sectional view of a driving device showing a second embodiment, and FIG. 6 is an explanatory diagram showing displacement of an optical principal point. In FIGS. A lens group, 12 is a movable ring, 13 is a sleeve integrally formed with the movable ring 2, 14 is a fitting hole provided at a front end of the sleeve 13 in the optical axis direction, and 15 is a sleeve 1
3 is a fitting hole provided at the rear end in the optical axis direction, 16 is a guide bar, 17 is a screw shaft, 18 is a connecting portion 19 of the moving ring 2, 1.
A rack which is incorporated in the screw shaft 17 and is screwed with the screw shaft 17 to transmit the rotation of the motor M to the movable ring. Reference numeral 20 denotes an optical principal point of the movable lens group 11, which are members indicated by reference numerals 1 to 10 in FIG. Is the same as

In the second embodiment, the guide bar 16 is made of SUS
It is formed of a magnetic material such as 420. And 2
Numeral 1 denotes a magnet as an urging means, which adds an urging force to the weight of the lens group 11 so that the guide bar 16 is always in contact with the sleeve fitting hole surface on the optical principal point 20 side on the sleeve. It is fixed.

When the sleeve length is sufficiently secured,
The fitting hole 14 on the optical principal point 20 side of the lens group 11 is
Even if the rack 18 and the sleeve rear end fitting hole 15 vibrate in conjunction with the runout, the moving ring 12 is stably fluctuated by its own weight. Along with the vibration of the mating hole 15, the sleeve front end fitting hole 14 also vibrates in a small amount without being able to be pressed down by its own weight. For this purpose, an urging means is used. In this case, the urging means 21 is used.
It is only necessary to provide one in the vicinity of the front end fitting hole 14, and it is possible to prevent image shaking by a simple and inexpensive configuration with a small number of parts.

In this embodiment, the magnetic attraction between the magnetic bar and the magnet is used as the urging means. However, the same effect can be obtained by disposing a spring or the like between the lens barrel (not shown) and the sleeve 13. can get.

[0024]

As described above, according to the invention of the present application, the optical principal point of the lens is located near the optical axis in the radial direction of the fitting hole on one end side of the sleeve of the moving ring holding the lens. The lens is mounted on the moving ring so that the center of gravity of the moving ring substantially coincides with the position of the optical principal point, and the driven member is mounted near the fitting hole on the other end of the sleeve. This has the effect of stabilizing the side fitting state, suppressing the radial displacement of the optical principal point of the lens, and preventing the image swing phenomenon.

Further, in the vicinity of the fitting hole on one end side of the sleeve, an urging force is added to the weight of the lens, and an urging member for constantly bringing the surface of the fitting hole on one end side into contact with the guide bar is provided on the sleeve. Even when the sleeve length is short and the urging means is required, it is sufficient to apply the urging means only in the vicinity of the principal point side fitting hole, and the image is formed by a simple and inexpensive configuration with a small number of parts. This has the effect of preventing shaking.

Further, since the above-mentioned driving device is provided for moving the lens holding member forward and backward in the optical axis direction, there is an effect that a photographing device having an effect of preventing the above-mentioned image swing can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a driving device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the first embodiment.

FIG. 3 is a front view of the first embodiment.

FIG. 4 is an explanatory diagram showing displacement of an optical principal point in the first embodiment.

FIG. 5 is a longitudinal sectional view of a driving device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing displacement of an optical principal point in the second embodiment.

FIG. 7 is a longitudinal sectional view showing a conventional driving device.

FIG. 8 is a longitudinal sectional view showing a driving device according to another embodiment.

FIG. 9 is a perspective view of a second conventional example.

[Explanation of symbols]

 1, 11 Moving lens group (lens) 2, 12 Moving ring 3, 13 Sleeve 4, 14 Front end fitting hole (One end fitting hole) 5, 15 Rear end fitting hole (Other end fitting hole) 6, 16 Guide bar 7 17 Screw shaft (drive shaft) 8, 18 Rack (driven member) 10, 20 Optical principal point 21 Magnet (biasing means)

Continuation of the front page (56) References JP-A-5-257048 (JP, A) JP-A-3-294813 (JP, A) JP-A-4-136906 (JP, A) JP-A-5-100137 (JP) , A) Japanese Utility Model Application Hei 5-45617 (JP, U) Japanese Utility Model Application Hei 5-90418 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B ⁷ /02-7/105

Claims (3)

(57) [Claims] A moving ring having a sleeve formed at both ends for holding a lens and being inserted into a guide bar arranged parallel to the optical axis; and a moving ring parallel to the guide bar. In a driving device having a driving shaft arranged to transmit a driving force in an optical axis direction to a driven member provided on the moving ring, and a driving source for driving the driving shaft, the driving device includes: The optical principal point of the lens is located near the optical axis in the radial direction.
In addition, the position of the center of gravity of the moving ring holding the lens is
The lens is moved so that it substantially coincides with the position of the optical principal point.
A driving device attached to a driving ring , wherein the driven member is attached to the sleeve in the vicinity of a fitting hole on the other end side of the sleeve. 2. An urging member, which adds an urging force to the weight of the lens in the vicinity of the fitting hole on one end side of the sleeve to constantly contact the surface of the fitting hole on one end side with the guide bar. The driving device according to claim 1, wherein the driving device is provided on the upper side. This provided with a driving device according to claim 3 lens holding member to claim 1 or 2 for advancing and retracting in the optical axis direction
An imaging device characterized by the following .