JPH08190041A - Drive device and photographing device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a drive device for moving a lens forward and backward in the direction of the optical axis, to suppress the displacement of the optical principal point of the lens in the radial direction and prevent an image shake phenomenon. A movable ring 2 that holds a lens 1 and has a sleeve 3 that is fitted into a guide bar 6 that is arranged parallel to the optical axis,
A drive shaft 7 that is arranged parallel to the guide bar 6 and that transmits a drive force in the optical axis direction to a driven member 8 provided on the moving ring 2.
And a drive source M for driving the drive shaft 7, the lens so that the optical principal point 10 is located near the optical axis in the radial direction near the one end side fitting hole 4 of the sleeve 3. 1 is attached to the moving ring 2, and the driven member 8 is attached to the sleeve 3 in the vicinity 5 of the other end side fitting hole of the sleeve 3.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 7 shows a conventional driving device. In FIG. 7, 1 is a lens held by a moving ring 2 and 3 is formed on the moving ring 2 parallel to the optical axis XX of the lens 1. The sleeve 6 is a guide bar 7 into which the fitting holes 4 and 5 formed at both ends of the sleeve 3 arranged in parallel with the optical axis in the lens barrel to be mounted on the main body of the photographing device (not shown) are fitted. Is a screw shaft as a drive shaft arranged in parallel with the guide bar 6, and 8 is a rack or a carriage as a driven member mounted between the connecting portions 9 formed integrally with the sleeve 3, and the illustrated example is a rack. It is screwed onto the screw shaft 7. Reference numeral 10 is an optical principal point of the lens 1, and M is 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, 9. Therefore, the moving ring 2 moves back and forth in the optical axis direction.

[0004]

However, in the above-mentioned conventional example, in order to obtain a smooth operation, the connecting portions 9, 9 of the rack 8 are provided in the vicinity of the center of gravity of the moving ring 2, but the screw shaft 7 is eccentric. When there is such a shake, the moving ring 2 itself vibrates subtly via the rack 8 in association with the shake caused by the rotation of the screw shaft 7, causing a continuous image shake phenomenon that is unsightly on the shooting screen. There was a point.

This image blurring phenomenon occurs when the moving ring 2 is displaced in the radial direction by the amount of looseness between the screw shaft 7 and the fitting holes 4 and 5 of the sleeve 3, so that the sleeve is biased by a magnet or the like. For example, Japanese Utility Model Laid-Open No. 5-90418 discloses a conventional example in which the fitting backlash is removed by the means to prevent image blurring.

FIG. 8 is a vertical sectional view showing a conventional drive device provided with this biasing means, and FIG. 9 is a perspective view of a part thereof.
The same parts as those of the conventional example shown in FIG. In FIGS. 8 and 9, 21a and 21b are 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 fitting play between the screw shaft 7 and the fitting holes 4 and 5 of the sleeve 3 can be reduced, but a plurality of biasing means 221a and 21b are required, which causes a problem of cost increase. was there.

The present invention has been made to solve the above-mentioned problems of the conventional example, and an object of the present invention is to provide a driving device with less image blur phenomenon. It is another object of the present invention to provide a driving device with a small image blur phenomenon by a simple and inexpensive structure with a small biasing means even if the sleeve length is short.

A further object of the present invention is to provide a photographing device equipped 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 drive device which holds a lens and which has a moving ring having a sleeve which is fitted into a guide bar arranged parallel to the optical axis and which is parallel to the guide bar. A drive device having a drive shaft for transmitting a drive force in the optical axis direction to a driven member provided on the moving ring, and a drive source for driving the drive shaft, in the vicinity of one end side fitting hole of the sleeve By attaching the lens to the movable ring so that the optical principal point is located in the vicinity of the optical axis in the radial direction of, and attaching the driven member to the sleeve in the vicinity of the other end side fitting hole of the sleeve, The entire weight of the moving ring 2 is applied to the fitting hole 4 side of the sleeve 3, and the fitting backlash between the hole surface of the sleeve fitting hole 4 and the guide bar 6 is always biased by its own weight in both the steady state and the driven state. Energized , It has become a stable state. As a result, it is possible to reduce the continuous image blur phenomenon that is unsightly on the shooting screen.

According to a second aspect of the present invention, in the drive device in the vicinity of the one end side fitting hole of the sleeve, the biasing force is added to the self weight of the lens so that the one end side fitting hole surface and the guide bar. By providing the urging member that constantly contacts with the sleeve on the sleeve, it is possible to more reliably reduce the image blur phenomenon due to the fitting backlash with a small number of used members.

According to the third aspect of the present invention, the photographing device according to the first or second aspect of the present invention is provided with the driving device for moving the lens holding member forward and backward in the optical axis direction. It is possible to reduce the image blurring phenomenon.

[0012]

【Example】

First Embodiment FIG. 1 is a longitudinal sectional view of a drive device showing a first embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, FIG. 3 is a front view of FIG. 1, and FIGS. Reference numeral 1 denotes a lens held by a moving ring 2; 3 is a sleeve formed on the moving ring 2 in parallel with the optical axis; 6 is fitted into fitting holes 4 and 5 at front and rear ends of the sleeve 3 to be parallel to the optical axis. 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 in the sleeve 3, as shown in the illustrated example. Has a rack screwed onto the screw shaft 7. Reference numeral 10 is an optical principal point of the lens 1, M is a motor as a drive source for driving the screw shaft 7 directly or through a gear or the like, which are the same as those of the conventional example shown in FIG. It is the same.

In this embodiment, the lens 1 is attached to 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 near the other end side fitting hole 5.

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, 9. Therefore, the moving ring 2 moves back and forth in the optical axis direction.
In this case, in the configuration of the present embodiment, 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, so that 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. 4, the sleeve 3
The entire weight of the moving ring 2 is applied to the side of the fitting hole 4 of, 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 always 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 amount of the fitting play between the guide bar 7 and the sleeve fitting hole due to the runout of the screw shaft 7, the sleeve fitting hole 4 side of the moving ring 2 moves. It is stable due to its own weight,
The screw shaft 7 is rotated about the side of the sleeve fitting hole 4 by the amount of vibration. That is, the sleeve fitting hole 5 side vibrates in the range of the angle θ about the sleeve fitting hole 4 side as the rotation center due to the fitting play.

As a result, the optical principal point 10 of the lens 1, which is integrally formed, also vibrates within the range of the angle θ, but the position of the optical principal point 10 is the sleeve fitting hole which is the center of rotation. Since it is arranged at the optical axis position in the vicinity of 4, the optical axis radial direction displacement ΔR is very small compared to the optical axis direction displacement ΔS 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 the present example, the displacement ΔS in the optical axis direction is the present example ≧ the conventional example, but the radial direction displacement is the present example ≦ the conventional example.

Since the radial displacement causes the image shaking phenomenon, as the mounting side of the rack 8 is further away from the sleeve fitting hole 4 side which is the rotation center, the optical principal point is obtained even at the displacement of the same angle θ. The radial displacement of 10 is large, and the amount of image shake is very large.

Further, although the displacement of the optical principal point 10 in the thrust direction becomes large in the structure of this embodiment, in order to provide smooth operation, A (the distance from the optical axis XX to the sleeve fitting hole) is provided. By configuring the relationship such that ≦ B (distance between sleeve fitting holes, that is, sleeve length), the displacement ΔS in the thrust direction of the optical principal point 10 is determined by the sleeve fitting hole 5 and the guide bar 6.
The amount can be less than the amount of fitting backlash. This displacement is 1
Since the displacement is about 0 m or less, the displacement is sufficiently within the permissible depth of focus for recognizing out-of-focus, and there is no adverse effect on the shooting screen.

Second Embodiment FIG. 5 is a longitudinal sectional view of a drive unit showing a second embodiment, and FIG. 6 is an explanatory view showing the displacement of the optical principal point. In FIGS. A lens group, 12 is a moving ring, 13 is a sleeve integrally formed with the moving ring 2, 14 is a fitting hole provided at the front end in the optical axis direction of the sleeve 13, and 15 is the 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, and 18 is a connecting portion 19 of the moving ring 2.
A rack which is incorporated in 9 and which is screwed to the screw shaft 17 and transmits the rotation of the motor M to the moving ring, 20 is an optical principal point of the moving lens group 11, and these 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
Reference numeral 1 denotes a magnet as an urging means, which adds the urging force to the own weight of the lens group 11 so that the sleeve fitting hole surface on the optical principal point 20 side and the guide bar 16 are always in contact with each other 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 has a screw shaft 17
Even if the rack 18 and the sleeve rear end fitting hole 15 vibrate in association with the runout of the sleeve, the weight of the moving ring 12 causes the rattling to be stably performed, so that when the sleeve length is short, the sleeve rear end fitting is performed. As the dowel hole 15 vibrates, the sleeve front end fitting hole 14 also vibrates in a small amount without being pressed down by its own weight. For this purpose, a biasing means is used. In this case, the biasing means 21
Need only be provided at one place in the vicinity of the front end fitting hole 14, and it is possible to prevent image shake with a simple and inexpensive structure 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, but the same effect can be obtained by disposing a spring or the like between the lens barrel and the sleeve 13 (not shown). can get.

[0024]

As described above, according to the invention of the present application, the optical principal point of the lens is arranged at the optical axis position near the one end side fitting hole of the moving ring sleeve holding the lens, and the other end is arranged. Since the driven member is attached near the side fitting hole,
There is an effect that the fitting state at the one end side is stabilized, the radial displacement of the optical principal point of the lens is suppressed, and the image shake phenomenon can be prevented.

In the vicinity of the fitting hole on the one end side of the sleeve, an urging member is added to the weight of the lens so that the urging member for constantly contacting the fitting hole surface on the one end side with the guide bar is provided on the sleeve. Even if the sleeve length is short and the biasing means is required, it is sufficient to apply the biasing means only in the vicinity of the fitting hole on the principal point side. It has the effect of preventing shaking.

Further, since the 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 image shake can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a drive device showing 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 a displacement of an optical principal point in the first embodiment.

FIG. 5 is a vertical cross-sectional view of a drive device showing 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 vertical cross-sectional view showing a drive device of a conventional example.

FIG. 8 is a vertical cross-sectional view showing a drive device of another embodiment.

FIG. 9 is a second conventional perspective view.

[Explanation of symbols]

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

Claims (3)

[Claims] 1. A moving ring having a sleeve for holding a lens and fitted into a guide bar arranged parallel to the optical axis, and a driven member provided on the moving ring arranged parallel to the guide bar and having an optical axis. In a drive device having a drive shaft that transmits a drive force in a direction and a drive source that drives the drive shaft, an optical principal point is located near the optical axis in the radial direction near the one end side fitting hole of the sleeve. The driving device, wherein the lens is attached to the moving ring, and the driven member is attached to the sleeve in the vicinity of the other end side fitting hole of the sleeve. 2. A biasing member for adding a biasing force to the own weight of the lens in the vicinity of the one end side fitting hole of the sleeve to keep the one end side fitting hole surface and the guide bar in constant contact with each other. The drive device according to claim 1, wherein the drive device is provided above. 3. An image pickup apparatus provided with the drive device according to claim 1 for moving the lens holding member forward and backward in the optical axis direction.