JPH0241009B2 - RENZUKUDOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens driving device for an automatic focusing camera, and more particularly to a lens driving device suitable for focusing a camera using a relatively large lens such as a single-lens reflex camera.

Various focusing cameras have been implemented using relatively lightweight lenses. In these cameras, a simple method is adopted in which the lens to be focused is set at one limit, eg, an infinity position, and then brought to a predetermined position by the biasing force of a spring or the like.

The lenses of 35mm single-lens reflex cameras, which are currently widely used, are quite heavy, so they are not compatible with the adjustment method described above. Currently, single-lens reflex cameras and other cameras use a method that uses a motor to wind the film, charge the shutter, etc.
It is undesirable to further incorporate a powerful motor for driving the lens into such a camera because it increases the size of the camera.

Camera interchangeable lenses are usually equipped with a distance ring, and by rotating this distance ring,
Focusing is performed by moving the objective lens forward and backward.

An object of the present invention is to convert rotation of the motor in one direction into rotation for driving the distance ring in a first direction and a second direction according to focus adjustment information, thereby rotating the motor in one direction of a motor drive camera. An object of the present invention is to provide a lens driving device that drives a lens using the rotation of the lens.

The configuration of a lens driving device according to the present invention for achieving the above object will be explained in conjunction with embodiments.
The gear 21 is a gear that rotates around the optical axis and drives an adjustment ring 22 that moves the lens forward and backward.

The first and second ratchet gears 14 and 15 are provided coaxially with the gear 21, and rotational forces in mutually opposite directions are transmitted to rotate the gear 21 in the forward or reverse direction.

The first and second crank gears 7, 8 are rotated in opposite directions by the rotation of the drive motor 1 in the first direction.

Note that these first and second crank gears 7, 8
The central axis of is omitted from the illustration.

First and second crank arms 11, 12
are the first and second ratchet gears 7, 8.
It has pawls 11a and 12a that engage with the first and second crank gears 7 and 8, respectively, and one end thereof is connected eccentrically to the first and second crank gears 7 and 8, respectively.

The biasing means 13 is provided with claws 11a and 12a on the first and second crank arms 11 and 12, respectively.
provides a biasing force in a direction that acts on the corresponding ratchet gears 14 and 15.

The electromagnetic device 16 includes solenoids 16a and 16b,
By being driven by these solenoids and acting on the other end sides of the first and second crank arms 11 and 12, only one of the crank arms 11 and 12 is engaged with the corresponding ratchet gears 14 and 15. It is formed from a pair of iron pieces 17 and 18 that restrict each movement range so that they fit together. The signal circuit 24 generates a lens drive signal to the solenoid of the electromagnetic device 16 so as to attract and hold one of the iron pieces 17 and 18.

In this way, the lens is driven forward and backward by the rotation of the motor 1 in the first direction.

The lens driving device according to the present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a perspective view showing an embodiment of a lens driving device according to the present invention.

In the figure, a drive motor 1 is provided with output shafts at the top and bottom. Only the rotation of the lower output shaft in the first direction (the counterclockwise rotation indicated by the arrow on gear 4 ) is transmitted via transmission gear train 3 . Note that a one-way rotation clutch is provided at portion 3a that transmits only rotation in the first direction and does not transmit rotation in the second direction. A bevel gear 5 is integrally provided on the gear 4, and a bevel gear 6 is also coupled to the bevel gear 5. A spur gear 7 is integrally provided with the bevel gear 6, and another spur gear 8 is further coupled to this spur gear 7.

These spur gears 7 and 8 form a crank gear, and crank pins 9 and 10 are provided at positions offset from the central axis of rotation thereof.

A first crank arm 11 and a second crank arm 12 are coupled to these 9 and 10, respectively. Each crank arm 11, 12 has a pawl portion 11a, 12a which is connected to a first ratchet gear 14 and a second ratchet gear 15, respectively, and is biased toward the ratchet by a spring 13.

The first and second ratchet gears 14 and 15 are provided integrally with the bevel gear 21.
is connected to a bevel gear provided on the adjustment ring 22. The electromagnetic device 16 is a solenoid 16
a, 16b and the iron piece 17 coaxially supported
and 18.

The iron piece 17 is moved clockwise by the spring 19,
8 is biased counterclockwise by a spring 20.

Each iron piece has pins 17a and 18a at one end, respectively.
is provided. FIG. 1 shows a state in which the iron piece 18 is suctioned and held by the solenoid 16b, and the iron piece 17 is not suctioned and held.

In this state, the iron piece 18 allows the pawl 2a of the crank arm 20 to connect to the ratchet gear 15, and the iron piece 17 pushes out the crank arm 11 with the pin 17a at its tip and prevents the pawl 11a from connecting to the ratchet gear 14. are doing.

Current is supplied to the solenoids 16a and 16b of the electromagnetic device 16 from a signal circuit. The state of supply of this current is limited to whether it is supplied to either one or neither, and is not supplied at the same time.

Now, in the state shown in Figure 1, the power to 16b is cut off.
Assume that 16a is energized. Since the iron piece 18 is no longer held by suction by 16b, the spring 20
Crank arm 1 rotates clockwise due to the force of
2 to the outside and 12a to the ratchet gear 1.
Move away from 5.

On the other hand, as the iron piece 17 is attracted, 17a is lowered and 11a of the crank arm 11 is moved to the ratchet 1.
It meshes with 4. The crank gear 7 is rotated in the direction shown by the arrow in the figure by the rotational force transmitted from the motor 1, and as the crank arm 11 swings up and down, the pawl 11a moves the ratchet tooth 14 one tooth in the direction shown by the arrow a. Rotate in minutes.

At this time, the crank arm 12 is also being swung up and down, but since the crank arm 12 is pushed outward by the pin 18a of the iron piece 18, its pawl 12a cannot be connected to the ratchet 15, so the gear 21 is (a ) direction to rotate the lens drive pin 23 supported by portions 22a and 22b. When the lens moves due to the rotation of this pin and focus adjustment is completed, the signal circuit 24 outputs the solenoid 1.
In order to de-energize 6a, the contact piece 17 is restored to the position shown, thereby separating the portion 11a of the crank arm 11 from the ratchet gear 14.

In order to rotate the adjustment ring 22 in the b direction, the adjustment can be made in the same manner as described above by turning on the solenoid 16a.

When the focus adjustment is completed in this manner, a coupling mechanism (not shown) couples the mirror drive mechanism with the gear train 3 to drive the mirror and operate the shutter. After the shutter operation is completed, the mirror returns and motor 1
The film winding, shutter charging, etc. are performed via the pinion gear provided above, and preparation for photographing is completed.

As described above, in the present invention, lens driving for focus adjustment is performed by controlling rotation of a drive motor in one direction using an electromagnetic device. Conventionally,
There is an idea to perform servo control using forward and reverse rotation of a motor to drive the lens, but forming such a servo system would require the use of a dedicated motor. However, according to the present invention, since only the rotation of the motor in one direction is utilized, the rotation in the other direction can be actively utilized for film winding and the like.

Next, in the device according to the present invention, an electromagnetic device is used to control the engagement and disengagement of the crank arm from the clutch, and when the lens drive is completed, it is separated from the drive mechanism before the crank arm, so manual adjustment from the lens side is also possible. Become.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a lens driving device according to the present invention. 1... Drive motor, 2... Output pinion, 3,
4,5,6...Transmission gear train, 7,8...Crank gear, 9,10...Crank pin, 11,12...
...Crank arm, 13...Spring, 14, 15...
...Ratchet gear, 16...Electromagnetic device, 16a,
16b... Solenoid of electromagnetic device, 17, 18...
Iron piece of electromagnetic device (armature), 19, 20...
Iron piece spring, 21...Bevel gear, 22...Adjustment ring, 2
3... Lens drive pin, 24... Signal circuit.

Claims (1)

[Scope of Claims] 1. A gear that rotates around the optical axis to drive an adjustment ring that moves the lens forward and backward; and a gear that is provided coaxially with the gear and receives rotational forces in opposite directions to rotate the gear in the forward or reverse direction. first and second ratchet gears; first and second crank gears rotated in opposite directions by rotation of the drive motor in the first direction; and engaged with the first and second ratchet gears, respectively. first and second crank arms each having a claw that is connected to the first and second crank gears at one end eccentrically;
and a biasing means for applying a biasing force to the second crank arm in a direction in which each pawl acts on a corresponding ratchet gear, a solenoid, and the other ends of the first and second crank arms driven by the solenoid. an electromagnetic device consisting of a pair of iron pieces that act on each side to restrict each movement range so that only one of the crank arms engages the corresponding ratchet gear; and an electromagnetic device that attracts and holds one of the iron pieces. and a signal circuit that generates a drive signal to a solenoid of the electromagnetic device, and configured to drive the lens forward and backward by rotation of the motor in the first direction.