JPH0511166A - Lens driving device for camera - Google Patents

Abstract

PURPOSE:To provide a lens driving device in which spring repulsive force for removing backlash is not changed regardless of a lens position and in which a stepping motor can be used for driving a lens. CONSTITUTION:A lens supporting frame 64 moves in an optical axis direction in a lens barrel 29 through a guiding bar 66. A connection frame 78 is screwed to a lead screw 70, and the connection frame 78 is connected with the lens supporting frame 64. When the stepping motor 72 turns, the lead screw 70 rotates, and the lens supporting frame 64 moves with the connection frame 78. Since a spring 88 for removing the backlash is provided between the connection frame 78 and a spring bearing 86 screwed to the lead screw 70 and moves with the connection frame 78, the elastic force of the spring is not changed even when the lens position is changed. Consequently, the stepping motor whose rotational torque is small can be used for driving the lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for a camera, and more particularly, it forms an image of light from a subject on a light receiving surface of a solid-state image pickup device through a photographing lens and photoelectrically converts the image by the solid-state image pickup device. The present invention relates to a lens driving device applied to an electronic still camera adapted to obtain a signal.

[0002]

2. Description of the Related Art An electronic still camera is required to be able to easily perform photographing, and is required to have a zoom device so that the focal length of a photographing lens can be continuously changed. In addition, the overall length of the lens does not change so as not to impair the portability and mobility of the electronic still camera, and air is not pumped inside the lens barrel, so dust does not enter the optical system. Some focus type zoom lenses are used.

In the inner focus camera, the variator lens and the compensator lens are arranged so as to be movable in the optical axis direction, and zooming and focusing are performed by this movement. That is, during zooming, the variator lens and the compensator lens move while maintaining a predetermined optical relationship, and during focusing, the compensator lens is moved to the in-focus position.

The lens support frame of such a lens is driven as follows. That is, as shown in FIG. 4, the lens support frame 12 is provided inside the taking lens barrel 10 and the guide bar 1
It is possible to move in the optical axis direction via 4. The lead screw 1 is attached to the outer frame 16 of the lens barrel 10.
8 is arranged in parallel with the guide bar 14, and the lead screw 18 is connected to a drive motor (not shown).
A connecting frame 20 is screwed onto the lead screw 18, and a pair of holding pieces 22, 22 are formed on the connecting frame 20. A projecting piece 24 from the lens support frame 12 is sandwiched between the holding pieces 22, 22 of the connecting frame 20, and accordingly, when the lead screw 18 is rotated by a drive motor (not shown), the lens supporting frame 12 is formed together with the connecting frame 20. Moving. Around the guide bar 14, the lens support frame 12 and the spring bearing 2
6, a coil spring 28 is disposed, and the coil spring 28 urges the lens support frame 12 to the left in the figure to backlash the threaded portion between the connecting frame 20 and the lead screw 18. To remove.

[0005]

However, the above-mentioned conventional lens driving device has a drawback that the repulsive force of the spring 28 becomes stronger as the lens support frame 12 moves to the right in the figure. Therefore, the drive motor needs to have a large rotation torque, and the stepping motor is not used.
D. A C motor is used.

However, D. Although the C motor can obtain a large rotational torque, it has a drawback that an encoder, a photo interrupter, etc. are required for positioning. The present invention has been made in view of such circumstances, and an object thereof is to propose a lens driving device for a camera in which the repulsive force of the spring does not change depending on the lens position and a stepping motor can be used for driving the lens.

[0007]

In order to achieve the above-mentioned object, the present invention comprises a taking lens barrel and a lens support frame which is guided by a guide member in the taking lens barrel and moves in the optical axis direction. A screw rod arranged in the photographing lens barrel in parallel with the optical axis, a stepping motor for rotating the screw rod, and a screw rod that is screwed into the screw rod and connected to the lens support frame to rotate the screw rod. Is provided between the connecting frame that moves in the optical axis direction to move the lens support frame, the connecting frame, and the spring receiver that is screwed into the screw rod, and eliminates the backlash of the screw portion of the connecting frame. And an elastic member that does.

[0008]

In the present invention, when the screw rod is rotated by the stepping motor, the connecting frame moves and at the same time the lens supporting frame moves. The elastic member for removing the backlash is arranged between the connecting frame and the spring receiver screwed to the screw rod, and moves together with the connecting frame. Therefore, the repulsive force of the elastic member does not change regardless of the lens position, and the stepping motor can be used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a lens driving device for a camera according to the present invention will be described in detail below with reference to the accompanying drawings. Figure 1
It is sectional drawing which cut | disconnected the lens barrel 29 of the electronic still camera which has an inner focus type zoom device by the vertical surface containing the optical axis P. FIG. This camera has a front fixed lens 30, a variator lens 32, and a variator lens 32 in order from the front on the optical axis P.
A compensator lens 34, a diaphragm 36, a master lens 38, a beam splitter 40, a relay lens 42, a finder mirror 44, and a CCD unit 46 are arranged.

The variator lens 32 and the compensator lens 34 are movable along the optical axis P, and the zoom drive and the autofocus drive are performed by this movement, and the variator lens 32 and the compensator lens 34 are driven during the zoom drive. Moves while maintaining a predetermined optical relationship, and during focus driving, the compensator lens 34 moves to the in-focus position.

The light split by the beam splitter 40 passes through the AE lens 48 and enters the AE sensor 52 and the dimming sensor 54 via the half mirror 50. The light emission of the diaphragm 36 or a strobe (not shown) is controlled based on the subject brightness information obtained by the light control sensor 54. The finder mirror 44 is a half mirror, and the light transmitted through the finder mirror 44 enters the CCD unit 46 and is captured as a captured image. Further, the light refracted by the finder mirror 44 is incident on the finder section 56, and the photographer can see the subject through the eyepiece lens section 58.

On the rear surface of the finder mirror 44, an A
The F half mirror 60 is attached, and the light transmitted through the finder mirror 44 and refracted by the AF half mirror 60 is an auto focus (A
F) The light enters the device 62, and the subject distance is measured. FIG. 2 shows the structure of the lens driving device of the present invention. The lens support frame 64 (of a compensator lens or variator lens) can be moved in the optical axis direction in the lens barrel 29 via the guide bar 66. ing. A lead screw 70 is arranged in parallel to the guide bar 66 on a frame 68 outside the lens barrel 29. The lead screw 70 includes a stepping motor 72, a gear 74, and
They are connected via 76. A connecting frame 78 is screwed onto the lead screw 70 via a screw collar 80, and a pair of holding pieces 82, 82 are formed on the connecting frame 78. The projecting piece 84 from the lens supporting frame 64 is sandwiched between the holding pieces 82 of the connecting frame 78, and therefore, when the lead screw 70 is rotated by the stepping motor 72, the lens supporting frame 64 moves together with the connecting frame 78. To do. A coil spring 88 is arranged around the lead screw 70 between the screw collar 80 and the spring receiver 86. The coil spring 88 urges the connecting frame 78 to the left in the drawing to connect the connecting frame 78. The backlash of the threaded portion between the lead screw 70 and the lead screw 70 is removed. As shown in FIG. 3, the spring receiver 86 is screwed onto the lead screw 70 and is prevented from rotating.

According to the lens driving device for a camera of the present invention constructed as described above, when the stepping motor 72 rotates based on a predetermined pulse amount, the gears 74 and 76 are rotated.
The lead screw 70 rotates via the. When the lead screw 70 rotates, the connecting frame 78 that is screwed into the lead screw 70 moves, and the lens support frame 64 moves accordingly. At this time, since the spring 88 is arranged between the connecting frame 78 and the spring receiver 86 screwed to the lead screw 70, the spring 88 moves together with the connecting frame 78 and the spring 8 is moved regardless of the lens position.
The repulsive force of 8 does not change.

The lens driving device according to the present invention, which has been described in connection with the electronic still camera in the above embodiment, can be applied to a general camera.

[0015]

As described above, according to the lens driving device for a camera of the present invention, since the repulsive force of the elastic member for removing the backlash does not change regardless of the lens position, it is possible to drive the lens support frame. It becomes possible to use a stepping motor.

[Brief description of drawings]

FIG. 1 is a sectional view of an electronic still camera to which the present invention is applied.

FIG. 2 is a sectional view showing a lens driving device of the present invention.

FIG. 3 is a half sectional view showing a main part of a lens driving device of the present invention.

FIG. 4 is a sectional view showing a conventional lens driving device.

[Explanation of symbols]

 29 ... Lens barrel 64 ... Lens support frame 66 ... Guide bar 70 ... Lead screw 72 ... Stepping motor 78 ... Connection frame 86 ... Spring receiver 88 ... Coil spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunori Nishijima 2-26-30 Nishiazabu, Minato-ku, Tokyo Within Fuji Shashin Film Co., Ltd. (72) Innovator Yasunori Kainuma 2-26 Nishiazabu, Minato-ku, Tokyo No. 30 Fuji Shashin Film Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A taking lens barrel, a lens support frame that is moved in the optical axis direction by being guided by a guide member in the taking lens barrel, and an optical axis is provided in the taking lens barrel. A threaded rod arranged in parallel, a stepping motor for driving the threaded rod to rotate, and a threaded rod that is screwed and connected to a lens support frame. When the threaded rod rotates, it moves in the optical axis direction to support the lens. A camera lens comprising: a connecting frame for moving the frame; and an elastic member arranged between the connecting frame and a spring receiver screwed into a screw rod to remove backlash of a screw portion of the connecting frame. Drive.