JPH11344326A - Position detecting mechanism for motor driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect and control the position of a moving member by constituting the mechanism in such a way that the actuation of the driven- side member of an intermittent mechanism can become less than one revolution over the full actuating extent of the moving member and a switch actuating section can be actuated one time only even when the moving member moves to the last of the extent. SOLUTION: Over the full actuating extent in the left-right direction of a lens driving member 3, a driven gear 14 is actuated less than one revolution. With camera release, a stepping motor 10, the lens driving member 3, a lens 1, etc., are actuated and, at the same time, an idler gear 12 meshed with an idler gear 4 and a driving gear 13 are rotated and a switch 11 is switched to a turned-on state from a turned-off state until the meshing between a carry gear and a tooth section ends. Thereafter, the driving gear 13 continuously rotates following the rotation of a rotor R, but the driven gear 14 rotates within the meshing extent of the carry gear and tooth section and the lens driving member 3 is moved to a prescribed position while the driven gear 14 is made to make intermittent motions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mechanism for detecting the position of a moving member driven by a motor.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a conventional example of a lens driving device in a motor driven camera. The lens 101 is
It is fixedly supported by the lens frame 102. The lens frame 102 is urged downward by a spring 102a, so that the pin 102b can move in the left-right direction.
03a. The rack gear 103b of the lens driving member 103 is gear-connected to a pinion gear 105 attached to an output shaft of a rotor R of a step motor 110 via an idler gear 104.

The rotor R is rotatably supported by a bearing (not shown), and is magnetized to four poles in the circumferential direction.
The two stators Sa and Sb are formed in a U-shape, and are wound with coils La and Lb, respectively. Coil L
When a known pulse as shown in FIG. 3 is repeatedly applied to a and Lb as shown in FIG. 3, a magnetic field is generated as shown in FIG.回 動 Rotate in steps.

As described above, since the rotor R takes the same state every four pulses, a convex portion 103c formed at one end of the lens driving member so that the initial position can be detected, and a stopper 106 provided on a main plate (not shown). And the switch 111 fixed to the ground plate (not shown)
F, switches from OFF to ON at the 2nd and 3rd pulse, 4
It is configured to be turned on after the pulse. The control circuit 107 is a distance measuring unit 108 that obtains information on the distance to the subject.
And the drive circuit 109 of the step motor 110 and the switch 111.

The operation of the above configuration will be described. FIG. 5 shows an initial state. By a release operation of a camera (not shown), a predetermined pulse determined based on distance information from the distance measuring unit 108 is transmitted from the control circuit 107 to the drive circuit 109.
To the coils La and Lb. Coil La, L
When the stator b is energized, the stators Sa and Sb are excited, and the rotor R is rotated clockwise to move the lens driving member 103 leftward and move the lens 101 downward via the pinion gear 105 and the idler gear 104. Let it.

The control circuit 107 switches the switch 1 at the fourth pulse.
An ON determination of 11 is performed, and if the result is ON, the operation is continued and the lens 101 is moved to a predetermined position. If OF
If it is F, the operation at the time of abnormality such as stopping the operation and displaying the abnormality is performed. Thereafter, after an exposure operation is performed by a shutter opening / closing device (not shown), the rotor R rotates backward and returns to the state shown in FIG. At this time, the control circuit 107 determines whether the switch 111 is OFF after outputting the predetermined pulse,
If it is OFF, the operation ends. If it is ON,
The reverse rotation pulse is output to perform the processing at the time of abnormality such as returning to the initial position.

[0007]

As described above, in the prior art, the projection 103c of the lens driving member 103, the stopper 106, and the switch 111 constitute an initial position detecting mechanism. When the lens stop position for focusing is large and the movement amount per pulse of the lens driving member is small, in order to keep the pulse of the step motor and the phase of the lens driving member constant, the convex portion 103c, the stopper 106, and the switch 111 Each position accuracy was required.

In the case where the member whose position is to be detected for improving the position accuracy is provided not on the lens driving member but on a member such as an idler gear which rotates one or more rotations,
Since there is one or more positions where the switch is turned off, the position of the lens driving member cannot be detected.
Further, in order to improve the positional accuracy in the former, a switch operating position and a means for adjusting a stopper position are provided,
In addition, it is disadvantageous in terms of cost because it is necessary to increase the precision of the above-mentioned components.

[0009]

In order to solve the above-mentioned problems, an intermittent gear mechanism is provided between a moving member and a switch operating portion, the amount of movement per rotation of a motor being larger than that of the moving member, and an intermittent gear. A switch actuating section is provided on a driven side member of the mechanism. In the entire operation range of the moving member, the operation of the driven side member of the intermittent mechanism is configured to be less than one rotation,
Even if the moving member moves to the end of the range, the switch operating section is operated only once.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a motor controlled to rotate freely forward and backward, a moving member driven by a motor via a gear train, and a position detection of the moving member are performed by an output signal from a control circuit. And a detection switch that outputs a signal to a control circuit, and is provided with an intermittent gear mechanism that is connected to a part of the gear train so that the moving amount per rotation of the motor is larger than the moving member. Is provided with a detection switch operation section for controlling the operation of the detection switch, and the operation of the driven member becomes less than one rotation even when the moving member operates over the entire operation range. It is preferable that the driven member is provided with an operating range restricting means for restricting the operating range of the driving member.

[0011]

FIG. 1 is a diagram showing an embodiment of the present invention of a lens driving device in a motor driven camera. Lens 1, lens frame 2, lens driving member 3, idler gear 4, pinion gear 5, step motor 10, control circuit 7, distance measuring unit 8, drive circuit 9, switch 11 and operation of switch 11 and coil La of step motor 10 , Lb are configured in the same manner as in the conventional example.

A second idler gear 12 meshing with the idler gear 4 and a drive gear 13 for performing a known intermittent operation together with a driven gear 14 described later are integrally formed and rotatably supported. The drive gear 13 has spar teeth 13a that mesh with the driven gear 14 and an arc portion 13b that regulates rotation of the driven gear 14. The driven gear 14 has a plurality of sets of teeth 14a meshing with the upper teeth 13a of the driving gear, and a plurality of arcs 14b related to the arcs 13b, and further includes a pin 14c for operating the switch 11, and an initial position. And a position restricting portion 14d to be engaged with the second member, and is rotatably supported. The stopper 6 is provided on a base plate (not shown) so as to be able to lock the position restricting portion 14d.

The idler gear 4 is located at a distance of 1 from the lens driving member 3.
The amount of movement per pulse is large, and the amount of movement is large when the driven gear 14 also meshes with the carry teeth 13a of the drive gear 13. Therefore, the lens driving member 3
Carry teeth 13 even when the driving amount per pulse is small.
The driven gear 14 is driven with a large drive amount when meshing with the a. The switch 11 is configured to be OFF in FIG. 2A and ON in FIG. 2B in which the rotor R has rotated by four pulses. That is, the first four pulses of the rotor R are configured so that the tooth portion 14a and the carry-up teeth 13a mesh with each other.
4 is driven. The lens driving member 3
The operation of the driven gear 14 is less than one rotation in the entire left-right operation range.

The operation of the above configuration will be described below. 1 and 2A show an initial state.
By the release operation of a camera (not shown), the step motor 10, the lens driving member 3, the lens 1
And the like, and the second meshing with the idler gear 4
The idler gear 12 and the driving gear 13 rotate clockwise, and the switch 11 is switched from OFF to ON while the meshing of the upper teeth 13a and the teeth 14a is completed from the state shown in FIG.

Thereafter, the driving gear 13 continues to rotate with the rotation of the rotor R, but the driven gear 14
The rotation is performed only in the range where the engagement between the a and the tooth portion 14a is performed, and when the arc portions 13b and 14b are engaged, an intermittent operation such as stopping is performed. As described above, the lens driving member 3 is moved to a predetermined position while the driven gear 14 is intermittently moved. Thereafter, after an exposure operation is performed by a shutter opening / closing device (not shown), the rotor R rotates backward and returns to the state shown in FIGS. 1 and 2A.

According to the present invention, since the intermittent gear mechanism is related to the idler gear 4 having a larger moving amount per pulse than the lens driving member 3, the driven gear 14 is
The amount of movement when meshing with 3a is also large. That is,
Even when the driving amount of the lens driving member 3 per pulse is small, the driven gear 14 is driven with a large moving amount. Therefore, by operating the switch 11 with the driven gear 14 or relating the switch to the stopper 6, the phase of the pulse and the stopper and the phase of the pulse and the switch can be accurately obtained. No working position accuracy is required.

Instead of the partial gear type as in the embodiment of the present invention, an intermittent gear means such as a Geneva gear using pins and grooves may be used. Although the switch of the embodiment of the present invention is mechanical, an electric switch using a known photo-interrupter so as to provide a slit hole in the driven gear and relate to the slit hole may be used. The torque is reduced, and the size and power consumption of the motor can be reduced. In the embodiment of the present invention, the stopper and the switch related only to the initial position side are provided, but may be related to the operation end side.

Although the embodiment of the present invention is driven by a step motor, a DC motor may be used. In this case, a pulse signal obtained from a slit disk associated with a motor shaft or a gear train, a pulse signal obtained from a photo-interrupter and the present invention are used. Such switches may be related as well. In the embodiment of the present invention, the intermittent gear means is provided from the idler gear 4 via the second idler gear 12, but may be related to the idler gear 4 or the pinion gear 5. Although the embodiment of the present invention is a lens driving device for a camera, another motor driving device may be used.

[0019]

According to the structure of the present invention, there is provided an intermittent gear mechanism which is connected to a part of a gear train driven by a motor and in which the moving amount per rotation of the motor is larger than the moving amount of the moving member, A position detection switch and a position regulating means are related to the driven member of the intermittent gear mechanism, and the operation of the driven member is less than one rotation in the entire operation range of the moving member. Since the position of the operating range is regulated, the position of the moving member can be accurately detected and the position of the movable member can be accurately regulated without requiring much accuracy of the switch and the components related to the position regulation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIGS. 2A and 2B are detailed views of the intermittent gear means according to the embodiment of the present invention, wherein FIG.

FIG. 3 is a waveform diagram of driving pulses and switches of a step motor according to an embodiment of the present invention and a conventional example.

FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention and the step motor of the conventional example.

FIG. 5 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Lens 2, 102 Lens frame 3, 103 Lens drive member 4, 104 Idler gear 5, 105 Pinion gear 6, 106 Stopper 7, 107 Control circuit 8, 108 Distance measuring unit 9, 109 Drive circuit 10, 110 Step motor 11 , 111 switch 12 second idler gear 13 drive gear 14 driven gear

Claims (2)

[Claims] 1. A motor controlled to be freely rotatable forward and backward by an output signal from a control circuit, a moving member driven via a gear train by the motor, and detecting a position of the moving member to the control circuit. A detection switch that outputs a signal, and an intermittent gear mechanism that is connected to a part of the gear train so that a movement amount per rotation of the motor is larger than the moving member, is provided on a driven member of the intermittent gear mechanism. A detection switch operation section for controlling the operation of the detection switch is provided, and even if the moving member operates over the entire operation range, the operation of the driven side member becomes less than one rotation. Position detection mechanism of drive unit. 2. The position detecting mechanism of a motor drive device according to claim 1, wherein an operating range regulating means for said moving member is provided on a driven side member of said intermittent gear mechanism.