JP3235022B2 - Step motor drive shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor driving shutter having a lens driving device in an automatic focusing camera.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 62-200339, during a return stroke after exposure, when a spring is charged from a lens stop position for focusing and returns to an initial position, a lens drive is performed. Since the load torque of the step motor increases in the energy storing process for accumulating the members such as the members, the pulse width to the step motor is expanded from that in the focus adjustment process and the exposure process, and the initial position is moved at a low speed and a constant speed. It is returning. Note that the pulse width of the step motor is set so that it can operate under the maximum load torque condition in the energy storage process.

[0003]

In a camera with a zoom lens, a multi-focus camera, or the like, which has many lens stop positions for focusing, as the number of lens stop positions increases, the amount of movement of the lens driving member and the load on the step motor increase. The torque increases. Therefore, it is necessary to increase the output torque of the motor to cope with the increased load torque. Generally, the output torque of a step motor is reduced by reducing the pulse width, and the motor speed is increased. Also, by increasing the pulse width, the output torque increases and the motor speed decreases.

[0004] For this reason, the speed of the stepping motor is reduced during the energy storage process during the return process, and the range of operation is also extended. Therefore, the operation time of the energy storage process is long, the photographing interval is long, and the shutter is not operated. There is a problem that the operation noise is irregular and uncomfortable, and the battery is consumed more. In the conventional motor, a step motor having a high output torque must be used in order to shorten the time of the energy storage process. However, such a step motor has a high cost, a large size, and a large current consumption. There's a problem.

[0005]

In order to solve the above-mentioned problems, in the present invention, the circuit means is set in advance so as to output a pulse having a plurality of widths, and the pulse width is determined from an initial position. the first step in luma matches the first lens stop stages of the return stroke through the focusing stroke and exposed stroke first
In the pulse width, the second stage from the first stage to the middle of the energy storage stroke in the return stroke is the second pulse width.
Third stage third pulse width until the return to Luo initial position
Their Re respectively Yes set, the third pulse width of the first
The second pulse width is set longer than the pulse width and longer than the first pulse width and shorter than the third pulse width. Therefore, while the load of the energy storage member is small, the motor can be driven at a high speed without increasing the torque relatively. When the load of the energy storage member is large, the torque can be increased.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens driving member reciprocatingly moving to a focus adjustment area, a step motor for driving the lens driving member, and a charging means for storing the power by the step motor to move the lens driving member in one direction. A shutter comprising circuit means for driving a stepping motor, wherein the circuit means has preset a plurality of expanded pulse widths for operating the energy-storing process. The configuration is such that the expanded pulse width is used as the load torque of the step motor increases.

[0007]

FIG. 1 shows a state before release. Moving member 1
A gear portion 1a meshed with a pinion 3a fixed to an output shaft of a step motor 3 via an idler gear 2 via an idler gear 2, and a pin 4 of a sector opening / closing lever 4 during an exposure stroke.
A sector opening / closing cam 1b engaging with a and a pin 1c engaging with a lens driving member 5 described later are formed. On the outer peripheral edge of the lens driving member 5, a protruding piece 5a that engages with a not-shown photographing lens, a gear portion 5b that meshes with a ratchet wheel 7 described later, and a pin 1 when the moving member 1 rotates counterclockwise.
and a contact portion 5c engaging with the moving member 1 is formed. The lens driving member 5 is urged clockwise by a tension spring 6 as an energy storing member, and is rotatably supported coaxially with the moving member 1. I have.

The ratchet wheel 7 has a plurality of claw portions 7a which can be engaged with a locking member 9 which is regulated by the electromagnetic magnet 8 and urged clockwise, and is locked out of the rotation locus of the claw portion 7a before the release. A cam portion 7b for retracting the member 9 and meshing with the gear portion 5b of the lens driving member 5. The locking member 9 can rotate only when the electromagnetic magnet 8 is demagnetized (OFF), and the electromagnetic magnet 8 is excited (ON).
During rotation, rotation is prevented. The control circuit 10 outputs a drive pulse to the step motor 3 determined by film sensitivity information and subject depth information from the photometry unit 11 and a drive pulse to the electromagnetic magnet 8 determined by distance measurement information from the distance measurement unit 12. Is what you do. The control circuit 10 has a ROM section 13 that stores data of a plurality of pulse widths (P1, P2, P3) for determining the speed of the step motor 3.

In this embodiment, the number of drive pulses of the stepping motor 3 in the focus adjustment process is 20, and the pulse width is three types. The first pulse width P1 <the second pulse width P2
<Regarding the relationship of the third pulse width P3 , the initial position in the energy storage process
Is set in advance to have a pulse width P3 in a range of less than 5 remaining pulses before returning to . Generally, the output torque of a step motor is reduced by reducing the pulse width, and the motor speed is increased. Also, by increasing the pulse width, the output torque increases and the motor speed decreases. Therefore, the first pulse width P1
Can operate the stepping motor at high speed but the torque is small, the third pulse width P3 has a large torque but the operation is slow, and the second pulse width P2 has an intermediate property between P1 and P3. Thus, during the return stroke, the pulse width is set to P1, P2 in accordance with the load applied to the step motor 3.
It has been changed to 2, P3 to shorten the return journey time.

[0010]

[Description of Operation] As shown in FIGS. 2 and 3, the control circuit 10 is operated by the release operation of the camera, and the distance measuring unit 12 is operated.
Number of lens stop steps AF for focusing with distance information from
S is determined, and the stepping motor 3 in the exposure process is determined based on the subject luminance information and the film sensitivity information from the photometric unit 11.
Are determined. Next, the electromagnetic magnet 8
ON prevents the locking member 9 from rotating clockwise,
The step motor 3 rotates forward to a position corresponding to the number of lens stop stages AFS under the condition of the first pulse width P1. As a result, the moving member 1 rotates clockwise, and the lens driving member 5
Initial follow the movement member 1 also by the urging force of the tension spring 6
Rotate clockwise from the position .

From the number of lens stop steps AFS and the initial position
When the electromagnetic magnet 8 is turned off at the point where the number of pulses coincides with each other, the locking member 9 rotates clockwise, and the locking member 9 engages with the claw portion 7a of the ratchet wheel 7, so that the ratchet wheel 7 Locked. When the ratchet wheel 7 is locked, the rotation of the lens driving member 5 is stopped, and the photographic lens (not shown) is stopped at the in-focus position. The moving member 1 is thereafter rotated clockwise from the initial position to the position of the number of pulses 20 with the first pulse width P1, and reaches the exposure operation area.

In the exposure step, the moving member 1 further rotates forward by the driving pulse determined by the above-described driving pulse conditions, and then reversely rotates to the position of the remaining 20 pulses until returning to the initial position. The cam 1b is engaged with the pin 4a of the sector opening / closing lever 4, and the opening / closing operation of the sector (not shown) is performed, so that an appropriate exposure opening is obtained. After the exposure process is completed, the process returns to the return process. The moving member 1 continues to rotate reversely until it reaches the position where the number of lens stop steps AFS coincides with the first pulse width P1. During this time, the lens driving member 5
However, it is locked to the locking member 9 via the ratchet wheel 7, and the urging force of the tension spring 6 does not load the step motor 3, so that it can operate at high speed.

Returning to the initial position during the return stroke
Until the number of remaining pulses until the return to the initial position becomes smaller than the number of pulses corresponding to the number of lens stop stages AFS until the remaining number of pulses becomes 0, this is an energy accumulation process of charging the tension spring 6. During this energy accumulation process, the load torque of the step motor 3 increases almost in proportion to the pulse. In the present embodiment, the pulse width change point during the energy accumulation process is determined by the load torque and the motor output torque. The number of remaining pulses is set in advance to the fifth pulse before returning to the initial position due to the relationship. First, the lens strike during the return stroke
Return to the initial position from the point where the number of steps AFS matches
The remaining number of pulses up to fifth pulse until that performs continued reverse rotation of the moving member 1 by the second pulse width P2, to further the initial position
The number of remaining pulses before returning is the initial position from the 4th pulse
Until the number of remaining pulses returning to the above is zero, the rotation is reversed at the third pulse width P3 and the operation is completed.

For this reason, the stepping motor can be operated at a high speed until the energy storing process is started, and can be operated at a relatively high speed when the load is small after the energy storing process is started. Motor torque can be increased. The maximum number of lens stop stages AFS is 20
In the return stroke at the time of step (1), the first pulse width P1 is omitted and the stepping motor 3 performs reverse rotation under the changing condition of the second pulse width P2 to the third pulse width P3.
2, the pulse width is P2 <P3. Therefore, unlike the conventional example, the entire range is not operated at a low speed corresponding to the third pulse width P3, and the disadvantages of the conventional example can be improved.

In the present embodiment, the pulse width (speed) of the accumulating process is set to two types, the second pulse width P2 and the third pulse width P3, and the remaining time until the pulse width change point returns to the initial position.
Although the number of pulses is the fifth pulse, the disadvantages of the conventional example can be further improved by increasing the types of pulse widths. It is set appropriately according to the type of torque and pulse width. In this embodiment, the lens drive and the exposure drive for focusing are performed by one step motor. However, the present embodiment is used in a conventional example in which only the lens drive is performed by the step motor (Japanese Utility Model Laid-Open Publication No. 3-14626). Is also good. In this case, the entire return stroke is an energy storage process, but the same effect can be obtained by operating the energy storage process with a plurality of predetermined pulse widths as in the present embodiment.

[0016]

According to the present invention, according to the present invention, the first stage in luma matches the first lens stop stages of the return stroke through the focusing stroke and dew <br/> out stroke, litter from the first stage < the second stage up to the middle of the energy storage stroke of the energy stroke ,
Increase in load torque of the step motor corresponding to the third stage in the return until the initial position from the stage, with the particular increase in load torque of the step motor corresponding to the prestressing force of the prestressing member in prestressed stroke, preset By driving the stepping motor using the pulse width that has been increased stepwise, the operation time of the energy storage process is shortened, and the time of the return process is shortened. And the current consumption can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a waveform chart showing the operation of the embodiment of FIG.

FIG. 3 is a flowchart showing the operation of the embodiment of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving member 3 Step motor 4 Sector opening / closing lever 5 Lens driving member 6 Energy storage means (tensile spring) 7 Ratchet wheel 8 Electromagnetic magnet 9 Locking member 10 Circuit means (control circuit) 11 Photometry unit 12 Distance measurement unit 13 ROM unit P1 First pulse width P2 Second pulse width P3 Third pulse width

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-200339 (JP, A) JP-A-62-156634 (JP, A)

Claims (1)

(57) [Claims] 1. A lens driving member that reciprocates to a focus adjustment area, a step motor that drives the lens driving unit, and a charging unit that is charged by the step motor and biases the lens driving member in one direction. Circuit means for driving the stepping motor, wherein the lens driving member moves the focus adjustment process from the initial position,
Return to the above initial position after going out and returning
Are those, in the circuit means Yes preset to output a pulse of a plurality width, the pulse width, the return stroke through the focus <br/> point adjustment stroke and the exposed stroke from the initial position in the first stage a first pulse width at luma matches the first lens stop stages of <br/>, the return stroke from the first stage
The second stage up to the middle of the energy storage process at
The third stage from the second stage to return to the initial position Yes set, respectively Re third pulse width Niso, the third pulse width is longer than the first pulse width, the second Wherein the pulse width is set longer than the first pulse width and shorter than the third pulse width.