JPH0774852B2 - Camera autofocus device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device for a camera, and more particularly, to an operating stroke when a distance member extends a photographing lens from a starting position to a focusing position based on focusing data. The present invention relates to an automatic focus adjusting device for a camera.

[Prior Art] As shown in FIG. 4, the conventional automatic focus adjusting device for a camera is provided with a photographing lens focus adjusting mechanism on the shutter unit side. The drive member 1 rotatably attached to the substrate 2 on the shutter unit side is a sector gear 1a on the circumference.
It is driven by a step motor 4 through an idler 3 that meshes with the step motor 4, and in accordance with a preset program, the step motor 4 performs forward rotation and reverse rotation for focusing, exposure, and return, in the forward and reverse directions. A sector opening / closing cam 1b for opening and closing a sector (not shown) by acting on the sector opening / closing lever 5 is formed on the periphery of the drive member 1 so as to project.

On the other hand, 6 is a distance member for actuating a photographing lens (not shown) via the lens driving unit 6a to move and set the photographing lens to the in-focus position, which is rotated to the substrate 2 on the shutter unit side similarly to the driving member 1. Installed to get. The distance member 6 is provided with a sector gear 6b that meshes with a pinion 7a that is integral with the ratchet wheel 7. Also, a spring 6c imparts a turning tendency to the clockwise direction in the figure, so that the distance member 6 turns together with the driving member 1. Has been done. Reference numeral 8 is a locking lever pivotally supported by a pin on the substrate 2 in a state of being imparted with right-handedness by a spring 8a, and is configured to be attracted and held by the electromagnet 9 via an iron piece 9a coupled to one end thereof. When the electromagnet 9 (also referred to as an AF magnet) is demagnetized, the electromagnet 9 is rotated clockwise in the drawing, and the claw at the tip thereof is engaged between the teeth of the ratchet wheel 7 to lock the distance member 6 at the focus position. Has been done.

On the other hand, the pinion 11a fixed to one end of the step motor 4 that drives the drive member 1 rotates the ratchet wheel 7 clockwise through the drive member 1 and the distance member 6 by the reverse rotation of the step motor 4 and pushes up the locking lever 8. . When the electromagnet 9 is energized at that time, the locking lever 8 is held at a position where the tip of the locking lever 8 does not lock the teeth of the ratchet wheel 7.

Then, the step motor 4 shifts to the normal rotation for the focusing operation, and transmits this rotation to the driving member 1 arranged on the substrate 2 via the pinion 11a fixed to the rotation transmitting shaft, and the spring 6c causes the rotation thereof. The following distance member 6 is rotated clockwise in the drawing. On the other hand, the rotation of the distance member 6 causes the scanning lever (not shown) to scan the held light emitting element, and the light receiving element (not shown) receives the light from the light emitting element as the reflected light from the subject, and at the focal point. The focus signal is output and the distance information is displayed in the viewfinder. Further, the focusing signal is used to turn off the electric current to the electromagnet 9 and rotate the locking lever 8 clockwise.
The ratchet wheel 7 is locked, the distance member 6 is locked, and the photographing lens is positioned at the in-focus position.

When the step motor 4 further rotates, the drive member 1 rotates clockwise and the cam portion 1b causes the pin 5a of the sector opening / closing lever 5 to turn left. When the pin 5a turns to the left, the step motor 4, which controls the rotation of the distance member 6, is released from the control by the operation of the shutter exposure operation, and performs a predetermined shutter opening / closing operation. The forward rotation and the reverse rotation of the step motor 4 are performed by the phase pulse generated by the step motor drive circuit 4a.

When the distance member 6 is in the starting position, the distance member 6 is always urged clockwise by the elasticity of the spring 6c, and the home switch HS provided as distance member position confirmation means is open. When the distance member 6 makes a transition from the starting position to the focusing operation, the home switch HS is closed, so it can be seen that the operation sequence of the distance member 6 is normal.

[Problems to be Solved by the Invention] Since the home switch HS is provided on the pin 6d of the distance member 6 in the automatic focus adjusting device for a camera having the above configuration, at least 1 to 4 step motors are required to close the home switch HS. 4 steps are required. Therefore, during the 1st to 4th steps, the distance member 6 cannot be locked as the focus setting position of the photographing lens, and there is a disadvantage that the operation stroke of the distance member 6 cannot be used.

[Object of the Invention] The present invention has been made in view of the above-described problems, and it is possible to reduce the invalid operation stroke of the distance member by comparing the focusing data and the number of steps of the step motor related to the rotation angle of the distance member. It is an object of the present invention to provide an automatic focusing device for a camera.

[Means for Solving the Problems] An automatic focus adjusting device for a camera according to the present invention includes a motor capable of forward / reverse rotation, and a distance member that operates according to the rotation of the motor to set a photographing lens to an initial position and extend the taking lens. A distance member locking mechanism that locks the distance member at a predetermined feeding position, and a distance member position confirmation means that confirms the position of the distance member at the operation monitoring point of the distance member and outputs a position confirmation signal, A counter that counts the number of steps relating to the locked position of the distance member by the distance member locking mechanism, and when the position confirmation signal is output at the operation monitoring point of the distance member, depending on the count value of the counter It is composed of a photographing lens setting means for setting the photographing lens at the extended position.

[Embodiment] An embodiment of an automatic focus adjusting device for a camera according to the present invention will be described in detail below with reference to FIGS.

The same components in FIGS. 1 to 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the home switch HS is a normally open contact composed of a movable contact h ₁ and a fixed contact h ₂ , and the tip of the movable contact h ₁ is supported by a pin 6d provided on the distance member 6. Pin 6d
A spring 6c is provided between and the pin 2a provided on the substrate, and the distance member 6 is always urged in the clockwise direction by the elasticity of the spring 6c. When the shutter button SW is not pressed, the distance member 6 is at the home position and the home switch HS is opened by the pin 6d. When the release button SW is pressed, the sequence of power-on and automatic focus operation (lens drive) is executed in the first stroke. The exposure operation and the film winding operation are executed in the second stroke. A pinion fixed to one end of a step motor 4 that drives the driving member 1.
11a rotates the ratchet wheel 7 clockwise through the driving member 1 and the distance member 6 by the reverse rotation of the step motor 4,
Push up the locking lever 8. When the electromagnet 9 is energized at this point, the tip of the locking lever 8 is held at a position where the tip of the locking lever 8 does not lock the teeth of the ratchet wheel 7. Then, the step motor 4 shifts to the normal rotation for the focusing operation, and transmits this rotation to the driving member 1 arranged on the substrate 2 via the pinion 11a fixed to the rotation transmission shaft, and the spring 6c causes this rotation. The following distance member 6 is rotated clockwise in the drawing. When the distance member 6 rotates clockwise in the figure, the movable contact h ₁ of the home switch HS which is being opened comes into contact with the fixed contact h ₂ by the movement of the pin 6d to be closed. In the home switch HS, the movable contact h ₁ is connected to the reference potential point, and the fixed contact h ₂ is connected to the input side of the forward / reverse rotation pulse sending unit 15 of the control circuit CPU. The phase pulse from the forward / reverse pulse sending unit 15 to the step motor drive circuit 4a is a shutter speed calculation unit 17 and a focus adjustment calculation unit to which the side light data and distance measurement data generated by the photometer 17a and rangefinder 18a are input. Determined at 18. The forward / reverse pulse sending unit 15 is a step motor drive circuit unless the home switch HS is opened.
Cannot send phase pulse to 4a.

Opening and closing of the home switch HS is determined at decision pox F ₈ lens set feeding program EXC ₂ shown in Figure 2. If the home switch HS is not closed, abnormal operation will occur, so the AF magnet 9 is turned off in step 21, and the reverse rotation (8 in step F _22).
+1) pulse is sent out and the power hold is set to L in process F _32.
To

Lens set feeding program EXC ₂ is power supply program EXC ₁
It is activated when the release button SW is judged to be on by the judgment box F ₁ and the processing F ₂ and the power is held. Immediately after the lens set feeding program EXC ₂ is started, the distance is measured in the process F ₃ and A provided in the 0 word of the lens set memory RSM shown in FIG.
Write the AF data AFn according to the distance measurement data in the F memory AFM. Note that the AF data is a maximum AF data corresponding to the maximum angle θmax of the distance member 6 is a numerical value equal to or less than AFmax.

0 in the first word of the lens set memory RSM shown in FIG.
A step counter STC is provided in the 11th to 11th bits, and the number STn of steps of the step motor 4 is entered in the step counter STC. In the second word, the exposure data memory EV
An M, a film sensitivity memory SVM, an aperture value memory AVM, and an exposure time memory TVM are provided, and EVn, SVn, AVn, and T data are entered.

Next, in process F ₅ , the reverse pulse is sent three times, and in process F ₆
Turn on the AF magnet. In this state, the locking lever 8 is held at a position where the teeth of the ratchet wheel 7 are not locked, and the distance member 6 is made to be able to follow the drive member 1.

In process F ₇ , 8 pulses of forward rotation are sent to the step motor 4.
In the judgment box F ₉ , it is judged whether or not the numerical value of the AF data AFn is 5 or less. If it is not less than 5, the number of steps STn, 5, is entered in the step counter STC in process F ₁₂ . AF
When the data AFn is 1 to 4, 5 reverse rotation pulses are sent to the step motor 4 in the process F10, and 0 of the step number STn is written in the sweep counter STC.

Next, in the judgment box F ₁₃ , the AF data AFn shows the number of steps ST.
One forward rotation pulse is sent in F ₁₄ until it becomes equal to n, and 1 is added to the value of the step counter STC in F ₁₅ . When AFn = STn is determined in the judgment box F ₁₃ , the AF magnet 9 is turned off in processing F ₁₆ , and the maximum AF data AFmax and step counter ST
Judgment box F ₁₉ until the number of steps STn of C becomes equal,
The drive member 1 is rotated in the clockwise direction by the flow of the processes F ₁₇ and F ₁₈ . The distance member 6 remains stopped at the position determined by the determination box F ₁₃ . When a AFmax = STn, the step counter STC treated F ₂₀ to 0, to start the metering Exposure program EXC _3.

When the photometric exposure program EXC ₃ is started, the photometry is performed in process F ₂₃ , the AF magnet 9 is turned on in process F ₂₄ , the exposure operation is performed in process F ₂₅ , and the AF magnet 9 is turned off in process F ₂₆ to complete all operations. , The distance member 6 is rotated counterclockwise by the driving member 1 until the home switch HS is opened in the judgment box F ₂₈ . Next, in the process F ₃₁ winding the film, the power hold to L in the processing F _32.

[Operation of the Invention] When the reverse rotation pulse is sent to the step motor 4 in the process F ₅ , the ratchet wheel 7 rotates in the clockwise direction, and the locking lever is placed on the outer peripheral portion of the ratchet wheel which has no teeth. AF magnet 9
Remains off and the distance member 6 is biased clockwise by a spring 6c. The rotation angle θn of the distance member 6 at this time is −θ ₃ from the rotation angle θ _{0 at the} initial position. When the forward rotation 8 pulse is sent to the step motor 4 in the process F ₇ , the rotation angle θn becomes θ ₀ with the forward rotation 3 pulse and becomes θ ₅ at the eighth pulse.

Since the point where the rotation angle θn becomes θ ₅ is the operation monitoring point, the position confirmation signal is output in the normal case. When the position confirmation signal is not output, the flow goes from the judgment box F ₈ to processing F ₂₁ . When the position confirmation signal is output, that is, when the home switch HS is closed, it is normal operation, and therefore the value of the AF data AFn entered in the AF data memory AFM in the judgment box F ₉ is 4 or more. If it is 4 or more, enter 5 in the step counter STC. Next, when the AF data AFn of the AF data memory AFM is, for example, AF ₁₀ , the process F _{14 is performed} until the step counter STC value becomes 10.
The forward rotation pulse is sent to the step motor 4 by and F ₁₅ .

The AF magnet 9 in the process F ₁₆ and the photographing lens is dispensed to the focus position is OFF, the latch so as not to move the photographic lens. Rotation angle θ of the distance member 6 in the latched state
Maximum rotation angle θmax when n is smaller than maximum rotation angle θmax
Then, the drive member 1 is continuously rotated forward. AF data AF
the number of steps of the step counter STC of the step counter STC (s) to zero in the process F ₁₁ with when n is 5 or less reversing the process F ₁₀ until the rotation angle θn is theta ₀ of the initial position
The flow goes to the judgment box F _{13 in the} same way as when STn is 5.

In the above-described embodiment, when the focusing step is 1 to 4, all the positions are rotated to the rotation angle θ ₀ by the process F ₁₀ , but the present invention is not limited to this. The AF data AF ₁ , AF ₂ , AF ₃ , AF ₄ By returning to the focal point corresponding to, the operating steps can be further reduced.

[Advantages of the Invention] An automatic focus adjusting device for a camera according to the present invention includes a motor capable of forward and reverse rotations, a distance member that operates according to the rotation of the motor to set a photographing lens to an initial position, and extends the distance, and the distance. A distance member locking mechanism for retaining the member at a predetermined feeding position, a distance member position confirmation means for confirming the position of the distance member at an operation monitoring point of the distance member and outputting a position confirmation signal, and the distance member engagement member. A counter that counts the number of steps relating to the restraining position of the distance member by the stop mechanism, and when the position confirmation signal is output at the operation monitoring point of the distance member, the photographing lens is moved according to the count value of the counter. Since it is constituted by the photographing lens setting means which is set at the extended position, there is an effect that the effective working angle of the distance member can be increased and the invalid working stroke can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic focus adjusting device for a camera according to the present invention, FIG. 2 is a flow chart of a lens set feeding program according to FIG. 1, and FIG.
FIG. 4 is a block diagram of data used in the lens set feeding program shown in FIG. 4, and FIG. 4 is a block diagram of a conventional automatic focus adjusting device for a camera. 4 Step motor 6 Distance member EXC ₂ Lens set feeding program (shooting lens setting means) HS Home switch (distance member position confirmation means) STC Step counter (counter)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03B 13/34 (72) Inventor Hiroyuki Koizumi 934-13 Shikato, Yotsukaido-shi, Chiba Stock Corporation Seikosha Co., Ltd. Chiba Works (72) Inventor Atsushi Takami 934-13 Shikato, Yotsukaido-shi, Chiba Stock Company Seikosha Chiba Works (72) Inventor Katsuhito Niwa 934-13 Shikato, Yotsukaido Chiba Stock Corporation Seikosha Chiba Business In-house (56) References JP-A-60-195529 (JP, A) JP-A 1-252910 (JP, A) Actual Kaihei 1-152314 (JP, U)

Claims (1)

[Claims] 1. A motor capable of rotating in the forward and reverse directions, a distance member which operates in response to rotation of the motor to set an image-taking lens to an initial position, and which is extended, and a distance for holding the distance member at a predetermined extension position. A member locking mechanism, distance member position confirmation means for confirming the position of the distance member at the operation monitoring point of the distance member and outputting a position confirmation signal, and a distance member locking mechanism for locking the distance member. After the count for counting the number of steps involved and the position confirmation signal at the operation monitoring point of the distance member are output, the photographing lens is set to the extended position in accordance with the count value of the counter, and the extended position is set to the above-mentioned position. An automatic focus adjusting device for a camera, comprising: photographing lens setting means for reversely operating the distance member to set the photographing lens at the extended position when the photographing lens is located at an operation monitoring point. .