JPH0219793Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens driving device for an autofocus camera, and more particularly to a lens driving device for an autofocus camera that controls the stop position of a lens.

Conventionally, the means for driving the lens of an autofocus camera is to send an autofocus signal to a pulse motor etc. via a control unit, rotate the lens frame body by this pulse motor etc., and fix it to this lens frame body. The lens frame is moved in the optical axis direction by sliding a fixed guide pin on the tapered cam or helicoid grooved cam, and the focal length is adjusted by driving the lens according to the autofocus signal depending on the distance of the subject. What goes well is known.

This method has the disadvantage that the mechanism becomes complicated and the cost becomes high. Therefore,
It has been difficult to use autofocus in inexpensive cameras due to cost considerations.

The present invention has been made in view of the above-mentioned facts, and it is an object of the present invention to provide a simple and highly reliable lens driving device for an autofocus camera that does not require a complicated mechanism.

In the present invention, a guide rod is brought into contact with a tapered surface cam formed on the surface of a guide disk or a helicoid groove surface cam formed on the side surface of the disk, and this guide rod is integrated with a lens frame to which a lens is fixed. By rotating the guide disk by a driving source such as an electromagnet, the guide rod comes into contact with the cam surface and moves in the optical axis direction, resulting in a lens frame that is integrated with the guide rod. and an L-shaped lens drive device for an autofocus camera that moves the lens in the optical axis direction, in which a three-step cam is formed on a part of the outer periphery of the guide disk, and one end of the cam is in contact with the cam surface. A stop lever is rotatably supported on the camera body side, a permanent magnet is fixed to the other end of the stop lever with one pole protruding, and the stop lever has a U-shaped iron core on the outside of the lens frame. An electromagnet for position control is provided, one pole of the permanent magnet is held between opposing ends of the iron core of the electromagnet with a constant gap, and one end of the stop lever to which the permanent magnet is fixed. When the stop lever reaches the center of the opposing iron cores of the electromagnet, the other end of the stop lever
A neutral spring is provided so that the stop lever comes into contact with the cam surface of the intermediate step of the step cam of the step, and the stop lever is stably neutral at this position, while the guide disk is rotated to another position outside the guide disk. Another electromagnet serving as a drive source and a drive lever are provided, one end of this drive lever and a guide disk are connected via a spring, and the tip of a permanent magnet fixed to the other end of the drive lever is in a non-energized state. The electromagnet is attracted and held inside one end of the U-shaped yoke of the electromagnet.

The lens driving device according to the present invention is configured as described above, and uses the autofocus signal to drive the electromagnet that is the power source to rotate the guide disk, and also uses the autofocus signal to control the stop position depending on the type of signal such as distance or distance. The stop lever can be stopped by activating the electromagnet to change the position of the stop lever and bring it into contact with the corresponding step of the step cam formed on the guide disk, so the guide disk can be stopped without the need for a complicated mechanism and without the need for an electric circuit. This simple structure allows the lens to be stopped.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lens driving device for an autofocus camera according to the present invention will be described in detail below with reference to the drawings.

Fig. 1 is an explanatory front view showing a lens driving device according to an embodiment of the present invention, Fig. 2 is a partial vertical sectional view thereof, Fig. 3 is a sectional view taken along line MM in Fig. 1, and Fig. 4 is an operation It is a circuit diagram.

As shown in FIGS. 1, 2, and 3, a lens 1 is fixed to a lens frame 2, and this lens frame 2 is attached to the camera body so as to be slidable in the optical axis direction. There is. This lens frame body 2 has a guide rod 3.
is fixedly installed, and its tip is slidably in contact with a tapered surface cam 5 formed on the surface of the guide disk 4. The tapered surface cam 5 is formed approximately at the center of the width of the guide disk 4 along a part of the circumference, and has a tapered surface as shown in FIG. The lens frame body 2 and the guide rod 3 are urged in the direction of the tapered surface cam 5 by a spring 6, so that the guide rod 3 is pressed against the tapered surface cam 5.

A spring fixing pin 7 is embedded in a part of the guide disk 4, and supports the other end of a spring 10 fixed to one end of a drive lever 9 rotatably supported by a rotating shaft 8. . This drive lever 9 is pressed against the fixing pin 7 by the biasing force of the spring 10. Further, a permanent magnet 11 is fixed to the other end of this drive lever 9.
When the electromagnet 12 is not energized, it is attracted to the inside of one end of a U-shaped yoke 13 of an electromagnet 12 provided on the camera body side outside the guide disk 4.

Furthermore, three step cams 14a, 14b, and 14c are formed on a part of the outer periphery of the guide disk 4. An electromagnet 15 is fixed to a part of the outside of the guide disk 4 toward the camera body, and both ends of a U-shaped yoke 16 are bent at right angles and face each other. A stop lever 18 is rotatably supported between the electromagnet 15 and the stepped cam 14 by a rotating shaft 17 fixed to the camera body.
This stop lever 18 is formed in an L-shape, and a permanent magnet 19 is provided at one end close to the electromagnet 15.
is fixed so that one pole, for example, the N pole thereof, protrudes, and at a position where this protruding end is approximately at the center of the opposing ends of the yoke 16, the other end of the stop lever 18 is placed at the center of the step cam 14. Stepped portion 14
A V-shaped spring 20 is fixed to the rotating shaft 17 so that the stop lever 18 is held in this position when the electromagnet 15 is not energized. The outward biasing force is stopped by stoppers 21 and 21' provided on both sides of the spring 20. Further, bent portions 22 and 22' bent at right angles are formed on both sides of one end of the stop lever 18 to which the permanent magnet 19 is fixed, and lightly support both ends of the spring 20.

The operation of the lens driving device configured as described above will be described below.

FIG. 4 is a schematic diagram showing the circuit section of this drive device. This circuit consists of a logic circuit section that combines four autofocus signals A, B, C, and D, a switch circuit section, and two excitation coil sections. Furthermore, this logic circuit section has one 3-input
It is composed of an OR gate element 30, one 2-input AND gate element 31, and one inverter element 34. Note that the signals A, B, C, and D are output in a high level state.

First, when the autofocus signal is in the closest zone, that is, the distance measurement range is 1.3 m or less, only the closest zone detection signal A is outputted by the action of the control section. Therefore, the output signal of the inverter 34 becomes a low level state (hereinafter referred to as an L state), the output of the AND gate 31 also becomes an L state, and switch circuits A and B do not operate. In the end, neither of the electromagnets 12 and 15 is energized, the guide disk 4 does not rotate, and the stop lever 18 is in the neutral position, so the amount of extension of the lens 1 remains at the maximum. Next, in the second zone, that is, when the distance measurement range is 1.3 m or more and 2 m or less,
Only the second zone detection signal B is output.

As a result, the switch circuit A operates and the electromagnet 15 is excited in the forward direction, so that the N pole of the permanent magnet fixed to the stop lever 18 becomes the S pole generated at the upper end 16a of the yoke 16 of the electromagnet 15. Because of the suction, the stop lever 18 moves towards the step cam 14c.
Move to the position where it touches. Also, inverter 3
Both the output signal of 4 and the output signal of OR gate 30 become high level (H state), the output of AND gate 31 becomes H state, and electromagnet 12 is excited in the opposite direction and is attracted to permanent magnet 11 (N pole). The polar face of the yoke 13, which had been
The permanent magnet 1 is magnetized by the repulsive force
1 is one pole of the yoke 13 (pole excited to N)
It moves further away and moves to the other pole (the pole excited by S) until it is attracted and held by its attractive force.
As a result, the drive lever 9 rotates counterclockwise around the shaft 8, and applies a biasing force to the spring 10. The force of this spring 10 causes the guide disk 4 to be driven by the pin 7 provided thereon. It tries to rotate until it hits lever 9 and is stopped. Here, the stepped cam portion 14c of the guide disk 4 is connected to the stop lever 18.
The tapered surface cam 5 provided on the guide disk 4 pushes out the guide rod 3 fixed to the lens frame 2 against the pressure of the spring 6 until it comes into contact with the lens 1 and stops.
Slightly retreat to the position corresponding to the measured distance. Next, in the third zone, that is, in the distance measurement range of 2 m or more and 4 m or less, only the third zone detection signal C is output.

Therefore, the electromagnet 12 is excited and the disk 4 is rotated in the same way as in the case of the detection signal B described above.
Since both switch circuits A and B do not operate, the electromagnet 15 is not excited and the stop lever 18 is maintained in a neutral state.
The guide disk 4 rotates until it comes into contact with the stepped cam 14b, and the lens 1 is retracted by the required amount. Next, in a long distance zone, that is, in a range of 4 m or more, only signal D is output.

This causes switch circuit B to work and electromagnet 1 to
5 is excited in the opposite direction to the detection signal B, and an S pole is generated at the lower end 16b of the yoke 16 of the electromagnet 15, attracting the N pole of the permanent magnet 19, so that the stop lever 18 comes into contact with the step cam 14a. Since the electromagnet 12 is also excited at the same time as described above, the guide disk 4 rotates until the stop lever 18 comes into contact with the step cam 14a and stops.
Retract the lens 1 to the in-position. In addition, by inputting a reset pulse to the electromagnet 12, it is possible to excite it in the opposite direction and return the drive lever 9 to the state shown in FIG.

As mentioned above, the stop lever can select the position of the step cam formed on the guide disk 4 depending on the type of autofocus signal, and therefore the stop lever can select the position of the stepped cam formed on the guide disk 4.
The rotation angle of the lens 1 is determined, and the amount of extension of the lens 1 can be determined. The relationship between the distance measurement range and the amount of lens extension can be maintained accurately by appropriately determining the pitch and set position of the step cam in advance.

Furthermore, it is also possible to use the step cam 14 and the stopper device (electromagnet 15 and stop lever 18) shown in the present invention in a conventionally known lens driving helicoid so that the amount of lens extension can be adjusted by a focus signal. It is. In such a case, the lens driving force does not use the electromagnet 12 as described above, but uses a normal spring urging force to apply a force to rotate the helicoid equipped with the lens in one direction, and uses the above-mentioned stopper device. , which controls the amount of feed.

As explained in detail above, the lens drive device of the present invention has an autofocus system that uses a guide disk and a stop lever that are operated by electromagnetic driving force, and a stop lever that engages with a stepped cam formed on the guide disk. This device is designed to drive and stop the lens of a camera.The lens driving part and the control part are connected only by an electric circuit, and there is no need for a complicated connection mechanism such as a charge mechanism or release mechanism, making it simple and reliable. is high, so its practical value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is an explanatory front view showing an embodiment of a lens driving device for an autofocus camera according to the present invention;
Figure 2 is a partial vertical cross-sectional view, Figure 3 is M of Figure 1.
-M sectional view and FIG. 4 are operating circuit diagrams. DESCRIPTION OF SYMBOLS 1... Lens, 2... Lens frame body, 3... Guide rod, 4... Guide disk, 5... Tapered surface cam, 9... Drive lever, 11, 19... Permanent magnet, 12, 15... Electromagnet, 14... Stage cam, 1
8... Stop lever, 20... V-shaped spring, 30... OR gate element, 31... AND gate element, 34... Inverter element.

Claims (1)

[Scope of utility model registration request] A guide disk having a tapered surface cam or a helicoid grooved surface cam, a guide rod guided by the cam, and a lens frame having a lens fixed thereon and moving in the optical axis direction via the guide rod as the guide disk rotates. In the lens driving device for an autofocus camera, the guide disk is provided with step cams in three stages for defining rotation stop positions, and an electromagnet having opposing poles is separately provided outside the lens frame body, and this electromagnet and the A stop lever is provided between the step cam and the step cam, one end of which is in contact with the step cam, a permanent magnet is fixed, and the other end is between the opposite poles of the electromagnet, and both ends of the stop lever energize the electromagnet. another electromagnet and a drive lever which serve as a driving source to rotate the guide disk at other positions outside the guide disk while pivoting with a neutral spring to be at the intermediate point of the stepped cam and electromagnet respectively when not in use; one end of the drive lever and a guide disk are connected via a spring, and the tip of a permanent magnet fixed to the other end of the drive lever is connected to the U of the electromagnet in a non-energized state.
A lens drive device for an autofocus camera, characterized by being suctioned and held inside one end of a letter-shaped yoke.