JPH0814652B2 - Camera lens drive and shutter opening / closing mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lens driving and shutter opening / closing mechanism of a camera in which a lens is driven and a shutter is opened / closed by one pulse motor.

(Prior Art) In a conventional general camera, a lens drive mechanism for moving a lens to a focus position and a shutter opening / closing mechanism that opens and closes a shutter for a predetermined time according to a photometric value are incorporated as separate and independent mechanisms. , They were supposed to work individually. Instead of such a conventional camera, it has been attempted to drive a lens and open / close a shutter with a single pulse motor.

The lens driving and shutter opening / closing mechanism by one pulse motor which has been considered so far drives the pulse motor at a constant pulse rate, and at the same time drives the lens by decelerating the rotational force of the pulse motor at a constant reduction ratio. Also, the shutter is opened and closed. But,
Since the load when driving the lens is larger than the load when opening and closing the shutter, it is necessary to match the torque of the pulse motor and the reduction ratio of the speed reduction mechanism to the lens driving side where a large load is applied, resulting in an increase in the size of the pulse motor. In addition, there is a problem that the operating speed as a whole becomes slower as the reduction ratio is increased.

(Object) An object of the present invention is to provide a lens driving and shutter opening / closing mechanism in which lens driving and shutter opening / closing can be performed by a single pulse motor. (EN) Provided is a camera lens driving and shutter opening / closing mechanism which can be enhanced as a whole.

(Structure) According to the present invention, the lens is driven by one pulse motor that rotates at an angle proportional to the number of pulses of the supplied pulse train and the output torque changes according to the pulse rate of the pulse train, and by the rotation direction of the pulse motor. In order to open and close the shutter, the intervening member connected to the pulse motor via the reduction gear and the first pulse train having the first pulse rate for driving the lens are supplied to the pulse motor and the shutter opening and closing is performed. In order to drive the lens, the second pulse train having the second pulse rate is supplied to the pulse motor, and the first pulse rate is lower than the second pulse rate. The output torque of the pulse motor is greater than the output torque required to open and close the shutter, and the rotational speed required to open and close the shutter is controlled. It is characterized in that the rotation speed is higher than that required for the drive.

Embodiments of a lens driving and shutter opening / closing mechanism of a camera according to the present invention will be described below with reference to the drawings.

In FIG. 1, the rotational driving force of the pulse motor 11 is passed through a speed reduction mechanism 12 having a constant speed reduction ratio to a blade opening / closing ring 13
Is transmitted to the partial gear 131 of the pulse motor 11, and the ring 13 is rotationally driven in the forward rotation direction and the reverse rotation direction according to the rotation direction of the pulse motor 11. A bent portion 132 is formed on the outer peripheral edge of the blade opening / closing ring 13, and the tip end surface of the bent portion 132 is an inclined surface 133. A cam 134 and a protrusion 135 are also formed on the outer peripheral edge of the blade opening / closing ring 13. Protrusion
A part of the position switch 25 has advanced into the passage of 135, and when the blade opening / closing ring 13 is at the reference position as shown in the figure, the position switch 25 is pushed by the protrusion 135 and turned on. . The protrusion 143 of the distance cam 14 is located close to the side of the tip of the bent portion 132.
The distance cam 14 is formed in a substantially cylindrical shape, and a ratchet portion 144 is formed on the outer periphery of the distance cam 14 following the protrusion 143, and another protrusion 142 is formed. A spring 15 is hung on the protrusion 142 to urge the distance cam 14 to rotate counterclockwise in the figure, and the stopper 27 causes the distance cam 14 to move by the urging force.
The rotation of the is regulated.

Here, in the drawing of the blade opening / closing ring 13, if the clockwise rotation is the normal rotation direction and the counterclockwise rotation is the reverse rotation direction, when the ring 13 rotates normally from the reference position, the bending portion 13
Push the projection 143 of the distance cam 14 on the passage at the tip of 2,
The distance cam 14 is rotated clockwise against the biasing force of the spring 15. Three uniform cam surfaces 141 are formed on the upper surface of the distance cam 14. The lower half portion of the lens frame 18 is loosely fitted in the cylindrical distance cam 14, and three pins 182 provided on the outer peripheral portion of the lens frame 18 are in contact with the three cam surfaces 141, respectively. The lens frame 18 integrally holds the lens 17. Further, a pair of fork-shaped portions 181 are formed on the outer peripheral portion of the lens frame 18, and the guide pins 20 are fitted into the fork-shaped portions 181, so that the lens frame 18 is guided by the pins 20 and the light of the lens 17 is guided. It is movable in the axial direction, but is not rotatable around the optical axis. A ring-shaped pressing spring 19 is provided above the lens frame 18, and three elastic arms 191 formed on the inner peripheral side of the spring 19 push the lens frame 18, and thus the pin 182 of the lens frame 18 is moved by a distance cam. It is designed to be pressed against the cam surface 141 of 14.

A stop pawl 16 is disposed on the side of the projection 143 and the ratchet portion 144 of the distance cam 14 so as to be rotatable in the horizontal plane by a shaft 28. The stop pawl 16 is formed in a bell crank shape, one arm end portion is a pawl portion 161 facing the ratchet portion 144, and the other arm end portion is also shown in FIG. So that the bent portion of the blade opening / closing ring 13
A bent portion 162 is formed diagonally upward at a position facing the tip inclined surface 133 of 132. The stop pawl 16 is urged to rotate clockwise by a spring 29, and normally the pawl portion 161 is provided with a distance cam 14.
It is adapted to engage with the ratchet part 144 of the.

There is a shutter substrate 26 below the blade opening / closing ring 13,
The shutter substrate 26 has a pair of shutter blades 22 and a shaft 31.
In addition to being rotatably provided in a plane parallel to the surface of the substrate 26, the sector lever 21 is rotatably provided in a plane parallel to the substrate 26 by the shaft 30. The sector lever 21 is urged to rotate in the clockwise direction by a spring 24, and a pin 211 fixedly penetrated through the arm end portion of the sector lever 21.
By contacting the outer peripheral surface of the blade opening / closing ring 13, the rotation of the sector lever 21 by the biasing force is restricted. The pin 211 of the lever 21 passes through elongated holes 221, 221 formed so as to intersect with the pair of shutter blades 22, 22, respectively. Pin 211 above
When the blade opening / closing ring 13 is reversely rotated from the reference position by a certain amount, the blade opening / closing ring 13 is pushed by the cam 134 of the blade opening / closing ring 13 and rotated counterclockwise against the biasing force. When the sector lever 21 rotates counterclockwise, the pin 211 rotates the pair of shutter blades 22 and 22 in opposite directions to open the optical path, and the blade opening / closing ring 13 rotates toward the reference position. By doing so, the sector lever 21 rotates in the clockwise direction to return the shutter blades 22 and 22 to rotate and close the optical path. Sector lever 21 pin
A trigger switch 23 is arranged on the side of the 211, and the trigger switch 23 is pushed by the pin 211 to be turned on in the normal state where the shutter is closed, but when the shutter is opened, the trigger switch 23 is pressed. Since the 211 escapes from the trigger switch 23, the trigger switch 23 is turned off.
The sector lever 21 forms a shutter opening / closing member.

In this way, the blade opening / closing ring 13 serves as an intervening member that drives the lens 17 in the optical axis direction and opens and closes the shutter depending on the direction of rotation of the pulse motor 11, and the pulse motor 11 moves from the reference position shown in the drawing. After being driven in the normal rotation direction by an amount corresponding to the distance measurement value, it is returned, and then is driven in the reverse direction by a fixed amount from the reference position and then returned to the reference position. The position switch 25 is for detecting the reference position.

The distance cam 14 serves as a distance setting member, and when the blade opening / closing ring 13 is normally rotated from the reference position, the distance cam 14 is rotated against the biasing force according to the amount of normal rotation. It is designed to be moved in the optical axis direction by an amount according to the distance measurement value. The sector lever 21 forms a shutter opening / closing member.

 Next, the operation of the mechanical portion will be described.

Now, when a shutter button (not shown) is pressed and the start switch is turned on, an automatic focus detection device (not shown) performs distance measurement, and the number of steps to drive the pulse motor 11 according to the distance measurement value is stored. The pulse motor 11 is driven according to the number of steps, and the blade opening / closing ring 13 is rotated from the reference position in the normal rotation direction, that is, in the clockwise direction in FIG. By the rotation of the ring 13, the bent portion 132 pushes the projection 143 of the distance cam 14 to rotate the distance cam 14 clockwise against the biasing force. The rotation amount of the distance cam 14 is determined by the rotation amount of the ring 13. The pin of the lens frame 18 is determined by determining the rotation amount of the distance cam 14.
The position of the cam surface 141 with which the 182 abuts is determined, and the lens 17 moves in the optical axis direction by an amount corresponding to the above distance measurement value to achieve focusing.

In this way, when the blade opening / closing ring 13 is normally rotated by an amount corresponding to the distance measurement value, the pulse motor 11 is subsequently reversed and the blade opening / closing ring 13 is returned to the reference position. At this time, the tip of the bent portion 132 of the ring 13 abuts on one arm end of the stop claw 16, but since the tip of the bent portion 132 is an inclined surface 133, the tip inclined surface 133 is formed. Does not pivotally displace because the submersion under the bent portion 162 of the stop claw 16 obliquely goes up and passes through the position of the stop claw 16 while elastically bending the stop claw 16. Further, the rotation of the distance cam 14 in the biasing direction by the spring 15 is prevented by the pawl portion 161 of the stop pawl 16 engaging the ratchet portion 144, and the lens 17 is held at the in-focus position.

The pulse motor 11 continuously drives the blade opening / closing ring 13 to rotate the blade opening / closing ring 13 in the reverse direction from the reference position by a predetermined amount. ring
The reverse rotation of 13 causes the cam 134 to push the pin 211 and rotate the sector lever 21 counterclockwise. By this rotation of the lever 21, the shutter blades 22, 22 are rotated to start opening the shutter. As soon as the shutter starts to open, the trigger switch 23 is turned off and the second is counted.When the second obtained by the photometric circuit (not shown) is reached, the pulse motor 11 is reversed again and the blade opening / closing ring 13 is moved toward the reference position. It can be rotated forward. The sector lever 21 rotates in the urging direction by the normal rotation of the ring 13, and the shutter blades 22 and 22 are rotated and returned to close the shutter.

Even after the shutter is closed, the blade opening / closing ring 13 is rotated in the forward direction to reach the reference position. When the ring 13 reaches the reference position, the tip of the bent portion 132 stops at the stop claw 1.
Push one arm end of 6 to rotate the stop pawl 16 counterclockwise against the biasing force, and the ratchet portion 1 by the pawl portion 161.
Release the lock of 44. The tip of the bent portion 132 further returns to the original position while sliding on the side surface of the arm end of the stop claw 16, and the stop claw 16 also returns to the original position by the urging force of the spring 29. As a result, the distance cam 14 is returned to rotate in the urging direction, and the cam surface 141 pushes up the lens frame 18 and the lens 1
Reset 7. In this way, when the blade opening / closing ring 13 returns to the reference position, the protrusion 135 is moved to the position switch 25.
Is turned on, and then the step motor 11 is rotated by several pulses and stopped to complete one sequence of operations.

FIGS. 3 and 4 show the above operation in a simplified manner. FIG. 3 shows the relationship between the lens operation and the shutter operation with respect to the rotation direction of the step motor, and FIG. 4 shows the operation of the entire camera. The outline of is shown. As shown in FIG. 3, when the step motor is driven in the normal direction from the reference position, the lens is driven in the optical axis direction by the number of steps corresponding to the distance measurement value, and the motor is returned to the reference position. After that, the shutter is opened by being driven in the reverse direction by a fixed amount, then the shutter is closed by driving the motor in the forward direction, and the motor is rotated in the forward direction to reach the reference position. The lens position is reset.
The number of steps for driving the lens may be set arbitrarily.

The operation of the entire camera is as shown in FIG.
With the release, first the distance is measured by the automatic focus detection device, then the lens is operated in the optical axis direction according to the distance measurement value, and then the shutter is opened and closed at the time according to the light measurement value.
Next, the lens position is reset, and finally the film is wound up to complete one sequence.

The lens driving and shutter opening / closing mechanisms described above are controlled by an appropriate sequence control circuit. FIG. 5 schematically shows an example of the control circuit. In FIG. 5, a trigger control 23 and a position switch 25 are connected to a sequence control CPU 32, and a start switch 35 that operates in conjunction with a release button is connected. In addition, the CPU 32 has an auto focus unit 33 and an auto exposure unit 34.
The pulse motor 11 is controlled in the forward rotation direction and the reverse rotation direction via the pulse motor driver 46 on the basis of the distance measurement value information and the exposure information. Since the sequence control circuit has no direct relation to the present invention, its detailed description is omitted.

Here, comparing the load and the required driving speed in the case of driving the lens and in the case of opening / closing the shutter, the load in the case of driving the lens is larger than the load in the case of opening / closing the shutter,
The driving speed when opening and closing the shutter needs to be faster than the speed when driving the lens. However, the motor for driving the lens and opening and closing the shutter is a single pulse motor 11
Further, the lens drive and the shutter opening / closing are performed while the reduction ratio of the reduction mechanism 12 remains constant. Therefore, as shown by the line A in FIG. 7, a pulse motor having such a characteristic that the torque becomes smaller when the control pulse rate becomes higher when driven by the power supply voltage used, is used. Pulse rate (this is the first pulse rate)
Is a pulse rate Pa that gives a torque Ta commensurate with the maximum load torque when driving the lens, and the pulse rate when the shutter is opened and closed (this is the second pulse rate) is
The pulse motor is driven by the pulse rate Pb so as to obtain the torque Tb commensurate with the maximum load torque when the shutter is opened and closed.

FIG. 6 shows the timing relationship between the switching of the pulse motor control pulse rate and the position switch 25 and the trigger switch 23. In FIG. 6, a, b, c,
As indicated by d, the pulse motor is in two-phase excitation, and the pulse motor control pulse rate in the shutter opening / closing range is higher than the pulse motor control pulse rate in the lens driving range. The lens drive operation and the shutter opening / closing operation are switched and the series of operations are stopped by the operation of the position switch 25.
By the operation of 25, the pulse motor control pulse rate can be switched. The CPU 32 shown in FIG.
Control means for supplying a first pulse train having a first pulse rate for driving the lens to the pulse motor 11 and supplying a second pulse train having a second pulse rate for opening and closing the shutter to the pulse motor 11. Are configured.

According to the embodiment as described above, the pulse motor control pulse rate when driving the lens with a high load torque is set lower than the pulse motor control pulse rate when opening and closing the shutter. Also, because the pulse motor control pulse rate when opening and closing the shutter is higher than the pulse motor control pulse rate when driving the lens, the high-speed operation required when opening and closing the shutter can be realized, and as a result, only one pulse motor is required. In addition, the pulse motor can be downsized, and the operating speed can be increased as a whole, although the speed reduction mechanism having a constant reduction ratio is used.

In addition, switching of the pulse motor control pulse rate is
It may be performed by an operation signal from the shutter time counting start switch, that is, the trigger switch 23 in the example of FIG. Further, the switching of the pulse motor control pulse rate may be performed according to a program predetermined by the CPU 32 in the example of FIG. However, it is more reliable to switch using a signal from a switch that operates in conjunction with the mechanical section, because the control corresponding to the actual operation of the mechanical section can be performed. The driving of the pulse motor is not limited to the two-phase excitation as described above.

(Effect) According to the present invention, the pulse motor control pulse rate when driving the lens with a high load torque is set lower than the pulse motor control pulse rate when opening and closing the shutter. Therefore, a high driving torque required when driving the lens can be obtained. In addition, since the pulse motor control pulse rate when opening and closing the shutter is higher than the pulse motor control pulse rate when driving the lens, the high-speed operation required when opening and closing the shutter can be realized, and as a result, only one pulse motor can be used. The pulse motor can be downsized and the operating speed can be increased as a whole even though it is used and a reduction mechanism having a constant reduction ratio is used.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a lens and shutter driving mechanism of a camera according to the present invention, FIG. 2 is a side view showing a portion of a stop pawl and a blade opening / closing ring of the same embodiment, and FIG.
FIG. 4 is a diagram showing the outline of the operation of the above embodiment, FIG. 4 is a flow chart showing the overall operation sequence of a camera having the mechanism according to the above embodiment, and FIG. 5 is an example of a control circuit applicable to the present invention. FIG. 6 is a timing chart showing an example of the operation timing relationship of each part of the mechanism according to the present invention, and FIG. 7 is a relationship between the control pulse rate and torque of the pulse motor used in the mechanism according to the present invention. It is a characteristic diagram showing an example of. 11 …… Pulse motor, 12 …… Deceleration mechanism.

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Claims (1)

[Claims] 1. A pulse motor that rotates at an angle proportional to the number of pulses of a pulse train supplied and whose output torque changes according to the pulse rate of the pulse train; and a lens that drives according to the direction of rotation of the pulse motor. In order to open / close the shutter, an intervening member connected to the pulse motor via a reduction gear and a first pulse train having a first pulse rate for driving the lens are supplied to the pulse motor, and the shutter is opened / closed. And a control means for supplying a second pulse train having a second pulse rate to the pulse motor for driving the lens by setting the first pulse rate lower than the second pulse rate. The output torque of the pulse motor required to open and close the shutter is greater than that required to open and close the shutter. Lens drive and the shutter opening and closing mechanism of the camera, characterized in that faster than the rotational speed which requires the rotational speed to the lens drive.