JPH0731208Y2 - camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a camera, and more particularly to a camera that performs automatic focusing and shutter operation by one motor.

[Conventional technology]

A stepping motor, a coreless motor, as a focus adjusting drive source and a shutter operating drive source for a compact camera,
DC motors are used. When performing automatic focus adjustment with such a camera during shooting, simply detecting that the shooting lens has reached the in-focus position and stopping the motor drive will cause the shooting lens to move to the in-focus position accurately due to the influence of inertial force. It is difficult to stop at that time, and particularly in the case of a mechanism in which the driving load of the taking lens changes depending on the in-focus position, it becomes more difficult and causes blurring.

Therefore, conventionally, the rotation angle of the motor is directly counted by a photo interrupter or the like, and the focusing lens group is driven at a high speed to a rotation angle predetermined by distance measurement calculation. Then, control is performed such that the motor is stopped at the in-focus position at high speed and accurately by decelerating while performing reverse brake, constant voltage drive, and the like.

[Problems to be solved by the device]

However, as described above, the focus adjustment is performed by complicated control such as high-speed driving of the motor, reverse rotation braking, and constant voltage driving, so that not only the structure of the control device becomes complicated but also the structure in which the driving load of the taking lens changes. Is
Since it is necessary to change the temporal pattern of the above-mentioned high-speed driving, reverse rotation braking, constant voltage driving, etc., there is a drawback that it becomes more complicated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a camera capable of performing highly accurate automatic focus adjustment and having a simple structure of a drive control unit of a focus adjustment motor. .

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention movably arranges a focus adjusting member (14) for advancing and retracting a photographing lens on a substrate (10) and urges the spring in one direction by a spring.
The focus adjusting member (14) is moved by a motor (19) to adjust the focus, and the focus adjusting member (14) is locked by a locking member (40) at the time of focusing to resist the biasing force of the spring. In the camera held at, the braking time of the motor (19) is determined in relation to the movement amount of the focus adjusting member (14), and the rotation speed of the motor (19) is determined based on the braking time before the focus position. It is characterized in that the photographing lens is held at the in-focus position by decelerating and stopping the motor (19) at the in-focus position.

[Action]

According to the present invention, the motor (19) capable of forward and reverse rotations is used, and the focus adjusting member (14) is rotated to move the photographing lens to perform focus adjustment. When approaching the in-focus position, the motor is braked by a reverse rotation brake or a short-circuit brake, so that the motor is quickly decelerated to accurately stop at the in-focus position. At this time, the motor (19) is stopped by changing the braking time according to the amount of rotation of the focus adjustment member (14), so that the focus adjustment member (14) is affected by load fluctuations such as changes in spring biasing force. It is possible to accurately stop at the in-focus position without performing high-precision automatic focus adjustment.

〔Example〕

Hereinafter, a camera according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view showing essential parts of a focus adjusting mechanism and a shutter operating mechanism of a camera according to the present invention. The focus adjusting mechanism and the shutter operating mechanism of the camera according to the present invention include a shutter substrate 10, a shutter unit 11, and a shutter drive ring 1.
2. The focus adjusting member 14, the photo interrupter 16, the lens frame 18, the DC motor 19 and the like.

The shutter substrate 10 is attached to the front portion of the camera body (not shown), and the shutter unit 11 is provided on the rear surface (the right side surface in FIG. 1) of the shutter substrate 10.

The shutter unit 11 includes two shutter blades 11A and 11B,
It is composed of support plates 13A and 13B. Shutter blade 11
A and 11B are axially supported by inserting shafts (not shown) provided on the back side of the shutter substrate 10 into the holes 15A and 15B, respectively.
The support plates 13A and 13B are attached to the shutter substrate 10 to form a blade chamber for shutter blades. A sleeve 20 is formed on the front surface of the shutter substrate 10, and the sleeve 20 includes a first sleeve 20A, a second sleeve 20B, and a third sleeve 20A having different outer diameters.
It consists of a sleeve 20C. A shutter drive ring 12 is rotatably attached to the outer circumference of the second sleeve 20B, and a focus adjusting member 14 is rotatably attached to the outer circumference of the third sleeve 20C.

A clutch lever 22 is supported on a mounting piece 23 formed on the outer periphery of the shutter drive ring 12 so as to be swingable around a shaft 23A and is biased by a spring 24 in a counterclockwise direction (arrow C direction). On the other hand, a pin 22A is planted in the clutch lever 22, and this pin 22A is the recess 12A of the mounting piece 23.
The clutch lever 22 is restricted to the recess 12A
With the function of the stopper as above, it swings only within a certain angle range.

The end of the mounting piece 23 of the shutter drive ring 12 is a shutter substrate.
Shutter drive ring 1 by abutting pin 10A implanted in 10
2 is prevented from rotating further counterclockwise from the position shown.

Further, a tooth row portion 26 is provided on a part of the outer periphery of the shutter drive ring 12.
Is formed, and the tooth row portion 26 has gears 27A, 27B, 27C, 27D, 27E.
Is connected to the DC motor 19 via.

A shutter blade drive lever 36 is pivotally supported by a shaft 34 planted in the shutter substrate 10 and is biased by a spring 37 in the clockwise direction (direction of arrow B). A drive pin 36A is planted rearward at the tip of the shutter blade drive lever 36, and the drive pin 36A is formed in the slot 3 formed in the shutter substrate 10.
Long holes 15 provided in the shutter blades 11A and 11B of the shutter unit 11 that penetrates 8 and is located behind the shutter substrate 10.
It is inserted through C and 15D. A driven pin 36B facing forward is planted in the approximate center of the shutter blade drive lever 36.

A cam 39 is formed on the peripheral surface of the shutter drive ring 12, and when the shutter drive ring 12 rotates clockwise, the cam 39 contacts the driven pin 36B and drives the shutter blades against the clockwise urging force of the spring 37. Turn lever 36 counterclockwise (arrow A direction)
Then, the shutter blades 11A and 11B are operated by pushing the shutter blades up and swinging them.

Further, a locking member is provided on the front surface of the shutter substrate 10 via a shaft 42.
40 is swingably supported and is urged to rotate counterclockwise by a spring 41. The other of the springs 41 is a torsion coil spring, which urges the gear 46 to rotate in the clockwise direction, and the gear 46 is rotatably supported on the front surface of the shutter substrate 10 via a shaft 44. A ratchet gear portion 46A is formed. The ratchet gear portion 46A is adapted to engage the locking claw 40A formed on the locking member 40, and the gear 46
It allows the counterclockwise rotation and regulates the clockwise rotation to form a one-way clutch. A cam 49 is formed on the outer periphery of the shutter drive ring 12, and when the drive ring 12 rotates counterclockwise, the cam 49 is locked by the locking member 40.
Abutting against the driven pin 40B planted in the upper part and pushing it up, the locking member 40 is rocked clockwise against the counterclockwise biasing force of the spring 41, and the engagement between the locking claw 40A and the ratchet gear 46A. Cancel the match.

The focus adjusting member 14 contacts the shutter drive ring 12 and
The sleeve 20C is rotatably attached and is urged to rotate counterclockwise via the gear 46 by a torsion spring 41 provided on the gear 46. A clutch lever engagement recess 52 is formed in the focus adjustment member 14, and this engagement recess 52 engages with the tip of the clutch lever 22 of the shutter drive ring 12. In this engaged state, the focus adjusting member 14 can rotate in the clockwise direction together with the shutter drive ring 12. Further, projections 54, 54, 54 are formed on the front surface of the focus adjusting member 14 on the same circumference. Further, a tooth row portion 48 is formed on a part of the outer periphery of the focus adjusting member 14,
The tooth row portion 48 meshes with the gear 46 that is integral with the ratchet gear portion 46A.

The photo interrupter 16 is provided in the recess 10B of the shutter substrate 10.
A notched disk fixed to the output shaft of the DC motor.
The number of rotation angles of the DC motor 19 is counted by 51.

The lens frame 18 is slidably arranged in the front-rear direction on a camera barrel (not shown), and is biased by the springs 56, 56, 56 toward the rear focus adjusting member 12. Focus adjustment member
The protrusions 54, 54, 54 on the front surface of 14 abut on the cam surfaces 58, 58, 58 formed on the rear end surface of the lens frame 18. As a result, when the focus adjusting member 12 rotates, the lens frame 18 moves back and forth together with the taking lens to adjust the focus.

FIG. 2 is a block diagram showing the control unit of the camera according to the present invention, and FIG. 3 is a timing chart showing the operation of the camera according to the present invention.

The operation of the camera according to the present invention constructed as described above
It will be described with reference to FIGS. 2, 3 and 4. In the initial position, the clutch engaging portion 52 of the focus adjusting member 14 shown in FIG.
Engages the clutch lever 22 of the shutter drive ring 12,
The focus adjusting member 14 is rotatable with the shutter drive ring 12 in the clockwise direction. Further, the driven pin 40B of the locking member 40 has a cam 49 formed on the shutter drive ring 12.
The locking claw 40A is mounted on the ratchet gear part 4 of the gear 46.
Far from 6A.

When the shutter release button is pressed (timing T _{0 in} FIG. 3), the controller 59 shown in FIG. 2 operates to activate the distance measuring device 62 to start distance measurement, and the distance signal to the controller 59. Is output. The controller 59 determines the amount of rotation of the focus adjusting member 14 based on this distance signal, and at the timing T ₁ of FIG. 3 via the motor drive circuit 60.
A reverse voltage is applied to the DC motor 19. At this time, if the shutter drive ring 12 is not at the regular start position, the mounting piece
The shutter drive ring 12 rotates counterclockwise and stops until the pin 23 contacts the pin 10A. The drive ring 12 does not rotate if it is in the normal position from the beginning. Then, after a lapse of an appropriate time, the DC motor 19 is normally rotated. This allows the shutter drive ring 12
Is rotated clockwise through gears 27E → 27D → 27C → 27B → 27A → tooth row portion 26. As a result, the focus adjustment member 14 is rotated clockwise with the shutter drive ring 12 by the engagement of the clutch lever 22 and the clutch engagement portion 52.

The motor drive circuit 60 is composed of a circuit for constant-speed driving by an electronic governor during normal rotation, high-speed reverse rotation during reverse rotation, and short-circuiting the motor terminals during braking, in response to a signal from the controller 59.

When the shutter drive ring 12 is rotated clockwise by a predetermined amount, the locking member 40 is swung counterclockwise by the action of the cam 49 and the urging force of the spring 41, and the locking claw 40A moves to the ratchet gear portion 46A. Contact. In this case, the locking claw 40A and the ratchet gear portion 46A function as a one-way clutch. That is, the focus adjusting member 14 is prevented from rotating in the counterclockwise direction against the biasing force of the spring 41 by the locking claw 40A, and is maintained in the state of being continuously rotatable only in the clockwise direction.

On the other hand, when the focus adjusting member 14 rotates as described above, the protrusions 54, 54, 54 formed on the focus adjusting member 14 push up the cam surfaces 58, 58, 58 of the lens frame 18 and gradually move the lens frame 18. Let out.

Since the focus adjusting member 14 is urged to rotate counterclockwise by the spring 41, the amount of force (the output load for the motor 19) for returning the focus adjusting member 14 to the counterclockwise direction by the amount of clockwise rotation is increased. fluctuate. When the motor 19 is short-circuited and stopped when the photographing lens reaches the in-focus position, the motor 19 is stopped after a certain time has elapsed from the time when the motor 19 was short-circuited due to inertia of the rotor. Therefore, in order to accurately stop the focus adjusting member 14 at the in-focus position, a means for stopping the motor by reducing the rotation speed of the motor to some extent before the stop position is used. This method is an effective means if the load on the motor is constant to some extent. However, as described above, the force required to stop the motor 19 (the output load of the motor) changes depending on the amount of rotation of the focus adjustment member 14, and as a result the stop time of the motor differs, resulting in a difference in the focus adjustment member.
14 cannot be stopped at the exact focus position. Therefore, in order to keep the rotation speed of the motor 19 constant when the motor 19 is stopped, when the load of the spring 41 on the motor 19 is small (when the rotation amount of the focus adjustment member is small), a large braking force and load are applied to the motor. When is large, a small braking force may be applied to control the rotation speed at the time of stop to be constant. Therefore, the photo interrupter
By inputting the output signal counted by 16 to the controller 59, the rotation amount of the motor 19, that is, the rotation amount of the focus adjusting member 14 is detected, and the controller 59 transfers the normal rotation to the motor drive circuit 60 according to the rotation amount. , Reverse rotation, short circuit signals are output.

In the controller 59, the DC motor
The time to short circuit 19 is output. In this case, the focus adjustment member
When the rotation amount of 14 is small and the biasing force of the spring 41 is weak, the short circuit time (brake time) is set to be large, and when the biasing force of the spring 41 of the focus adjustment member 14 is large, the short circuit time is set to be short. To be done. When the DC motor 19 is short-circuited between the timings T ₁ ′ and T ₂ ″, a counter electromotive force is generated in the DC motor 19 and the braking force acts on the motor 19, and at the timing T ₂ , the rotation speed of the motor 19 is the set value. Then, when a reverse rotation signal is output from the controller 59 to reverse the rotation of the motor 19 at the timing T ₂ shown in Fig. 3, the motor 19 is quickly stopped and the reverse rotation is started.
Is quickly stopped at the accurate focus position, and at this time, the focus adjusting member 14 is held at the focus position by the action of the locking member 40 against the biasing force of the spring 41. Therefore, the lens frame 18 can be held with an accurate extension amount.

Next, when the DC motor 19 is rotated in the reverse direction by the signal from the controller 59, the shutter drive ring 12 is rotated counterclockwise, whereby the clutch lever 22 is swung in the direction of arrow C by the rotational biasing force of the spring 24. Then, the engagement with the clutch engagement portion 52 is released. Then, in response to a command from the controller 59, the motor 19 is short-circuited again and the brake is applied so that the motor 19 will not overrun during the next forward rotation.
Set the rotation speed of 19 to the set value at timing T ₃ . In this state, since the locking claw 40A is engaged with the ratchet gear portion 46A, the focus adjusting member 14 does not rotate regardless of the biasing force of the spring 50. As a result, the shutter drive ring 12 becomes independently rotatable and shifts to the timing T ₃ which is the exposure control stage. Motor like this
Since 19 is stopped immediately, it is possible to move quickly to the exposure control stage.

At this point, the urging force of the spring 41 is the shutter drive ring.
Since the load is not applied to the motor 12, the load on the motor 19 is constant. Therefore, the braking time from the timing T ₂ ′ to T ₂ ″ may always be constant.

By forward the timing T ₃ DC motor 19 again after only a shutter drive ring 12 is rotated clockwise. At timing T ₄ , the cam 39 abuts the drive pin 36B of the shutter blade drive lever 36, causing the interlocking lever 36 to swing in the direction of arrow A against the biasing force of the spring 37, so that the shutter substrate 10 is moved. The provided shutter unit 11 is operated, the shutter blades 11A and 11B are opened, and exposure is started. The controller 50 is connected to an exposure control unit 66 to which the subject brightness measured by the photometry unit 64, film sensitivity, diaphragm, etc. are input, and the timing T ₅ for closing the shutter blades 11A, 11B under the control of the exposure control unit 66. Is determined and the shutter speed is automatically controlled.

After reaching the timing T ₅ , the DC motor 19 is rotated in the reverse direction, and the shutter drive ring 12 rotates counterclockwise. Thereby, the shutter blade driving lever 36 is returned in the direction of the arrow B by the urging force of the spring 37, the shutter unit 11 is a shutter blade 11A, 11B performs a closing operation, the shutter blade 11A at the timing T _6, 11B is completely closed To be That is, the opening / closing operation of the shutter is performed between the timings T _{4 and} T ₆ .

After performing the opening / closing operation of the shutter, the DC motor 19 is continuously rotated in the reverse direction under the control of the controller 59 to return the shutter drive ring 12 to the initial position. At this time, the clutch lever 22 comes into contact with the boss 43 formed on the shutter substrate 10, and the spring 24
Swinging clockwise (arrow D direction) against the urging force of
The focus adjusting member 14 is positioned so that it can be engaged with the clutch engaging portion 52.

Further, the cam 49 of the shutter drive ring 12 abuts the pin 40B of the locking member 40, and the locking member 40 is swung clockwise against the biasing force of the spring 41 to lock the locking claw 40A and the gear 46. The engagement with the ratchet gear portion 46A is released. This allows the gear 46
Becomes freely rotatable. Therefore, the focus adjustment member
14 is released from the regulation by the gear 46, is rotated counterclockwise by the urging force of the spring 41 through the gears 46 and 48, and is returned to the initial position.
The urging force of 56 and the action of the cam 58 return to the initial position.
As a result, each mechanism shifts to the timing T ₇ which is the initial position.

As described above, the DC motor 19 is driven at a constant speed, and at the time of focusing, the DC motor 19 is driven for a time related to the rotation amount of the focus adjusting member.
Braking to reduce motor speed. Therefore, the DC motor 19 can be quickly stopped without performing complicated control such as driving, reverse braking, constant voltage driving, and stopping of the motor. This enables highly accurate automatic focus adjustment without being affected by motor load fluctuations. Moreover, automatic focus adjustment and shutter operation can be performed by one motor, and a series of sequence control can be simplified.

Although a DC motor was used as the drive source in this embodiment,
Not limited to this, any motor may be used. Further, although one motor is used in this embodiment, motors for driving the shutter and for adjusting the focus may be used respectively.

[Effect of device]

As described above, according to the camera of the present invention, after focusing, the motor is quickly stopped at the fixed position by changing the braking time of the motor according to the amount of rotation of the focus adjustment member. The focus is accurately stopped at the in-focus position without being defocused due to a change in force or spring load, and highly accurate automatic focus adjustment is possible. Moreover, since the motor is driven at a constant speed, control of driving the motor can be simplified.

[Brief description of drawings]

FIG. 1 is an exploded view showing a main part of a focus adjusting mechanism of a camera according to the present invention, FIG. 2 is a block diagram showing a control unit of the camera according to the present invention, and FIG. 3 is an operation of the camera according to the present invention. It is a timing chart shown. 10 ... Shutter substrate, 12 ... Shutter drive ring, 14 ...
… Focus adjustment member, 16… Photo interrupter, 19…
… DC motor, 22 …… Clutch lever, 36 …… Shutter blade drive lever, 40 …… Locking member, 57 …… Controller.

Claims (1)

[Scope of utility model registration request] 1. A focus adjusting member for moving a photographing lens forward and backward is movably arranged on a substrate, and is urged to move in one direction by a spring, and the focus adjusting member is moved by a motor for focus adjustment. In a camera that holds the focus adjusting member at the in-focus position against the urging force of the spring by the locking member during focusing, the braking time of the motor is determined in relation to the movement amount of the focus adjusting member, and the in-focus position is determined. A camera characterized in that the photographing lens is held at the in-focus position by decelerating the rotation speed of the motor on the front side based on the braking time and stopping the motor at the in-focus position.