JPS6273243A - Automatic focus adjusting device for camera - Google Patents

Abstract

PURPOSE:To secure the stopping operation of a photographic lens and to make an automatic focus adjustment with higher precision by stopping an electromagnetic driving means temporarily with a distance detection signal and locking the photographic lens or a control member during the period. CONSTITUTION:A two-division sensor 8 receives pulse light from a light emitting element 9 as reflected light from an object and outputs a focusing signal when the outputs of the two sensors coincide with each other. This output signal is inputted to a microcomputer and a delay circuit to stop a stepping motor 3 for a specific time and also power off an electromagnet 6 with the output of the delay circuit. The microcomputer stops the stepping motor 3, so a ratchet wheel 5 is also stopped and a lock tooth part 5a and a lock lever pawl 7c engage each other securely. If there is a gap between the bottom part of the lock tooth part 5a of the ratchet wheel and the lock lever pawl 7c, the stepping motor 3 rotates again slightly to eliminate the gap, so that the distance ring 2 on which the photographic lens is mounted stops at a proper position.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an automatic focusing device for a still camera, etc., and more specifically, the present invention relates to an automatic focusing device for a still camera, etc. The stopping position of the photographing lens in a device that detects the distance and, based on the result, drives the photographic lens in an electric manner, or electromagnetically drives a member that controls the movement of the photographic lens, and locks the photographic lens in an appropriate position. This makes it possible to control with higher precision.

[Prior art]

Conventionally, as disclosed in Japanese Patent Laid-Open No. 140532/1984, for example, a cam was formed on the lens barrel, and as the lens barrel rotated, a light projecting element scanned and reflected light from the subject. An automatic focus adjustment device has been proposed that cuts off the current to the lens mooring magnet when a focus signal is detected, engages a stop claw with a ratchet on the lens barrel, and stops the lens at the focus position. There is.

However, in such devices, there is a mechanical delay time from when the focusing signal is output until the locking magnet is activated, and it is necessary to take this delay into account and make adjustments. This has the disadvantage that the variation in the focal length affects the accuracy of focus adjustment.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-precision automatic focusing camera without the disadvantages of the above-mentioned conventional devices.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is an embodiment of the present invention showing the state before release. FIG. The code 1 in the figure is the long groove 1a+
Bins 1d and 1d on a fixed substrate (not shown) are connected through 1a'.
' is a scanning plate movably attached to the ', and a light emitting element 9 is attached to the scanning plate. Further, the scanning plate 1 has a spring 1b that biases the left side, and the vertical bending portion 1 comes into contact with the protrusion 4a of the upright lever 4.
ci;lj.

The drive lever 4 rotates around the bin 4b tray on the fixed plate, and the bin 4C is engaged with the cam 2C of the distance ring 2. distance ring 2
, there are a rack portion 2a that meshes with the pinion 3a to receive the driving force from the step motor 3, and a rack portion 2b that meshes with the pinion 5b of the ratchet wheel 5. The ratchet wheel 5 has locking teeth 5a. The locking lever 7 is rotatably attached to the center of the pin 7b2 on the fixed plate while being given right rotation by a spring 7a. The iron piece 6a of the solenoid 5B is connected to a locking lever 7. When the electromagnet 6 is demagnetized, the pawl 7c provided at the end of the locking lever 7 rotates to the right and engages with the locking tooth 5a on the ratchet wheel 5.

Next, the operation of the above-mentioned constituent mechanism will be explained.

When the release member (not shown) is pressed down in the pre-release state shown in Fig. 1, the main switch S
1 is closed, the step motor 3 rotates, the distance ring 2 rotates to the right in the figure, and in conjunction with this, the drive lever 4 rotates, causing the scanning plate 1 to travel to the right in the figure. . At the same time, the electromagnet 6, which is excited, attracts the iron piece 6aQ and locks the locking lever 7.
It is held in a position where it does not come into contact with the locking tooth portion 5a. The light emitting element 9 starts emitting pulsed light toward the object at the arm end of the scanning plate 1 which has started traveling rightward.

On the other hand, the two-split sensor 8 receives the pulsed light from the light emitting element 9 as reflected light from the subject, and outputs a focus signal sound when the outputs of the two sensors match. This output signal is input to all the microcomputers and the delay circuit, and the three step motors are stopped for a predetermined period of time, and the electromagnet 60 is completely energized by the output of the delay circuit. Attraction by electromagnet 6? The unlocked locking lever 7 is rotated to the right by the biasing force of the spring 7a, and its pawl 7cf is brought into engagement with the locking tooth portion 5a. Since the step motor 3 is stopped by the microcomputer, the ratchet wheel 5 is also stopped and the engagement between the locking teeth 5a and the locking lever pawl 7C is ensured. After that, if there is a gap between the trough of the ratchet tooth 5a and the locking lever pawl 7C, the step motor 3 will rotate slightly again and operate in the direction to eliminate the gap Pl-. Okay, the distance ring 2 with the photographic lens attached stops at an appropriate position.

FIG. 2 shows another embodiment of the invention. The scanning plate, designated by reference numeral 1', has on its outer periphery a rack 1/b which engages with a pinion 3'a, and a cam 1/c which engages with a pin 5'c on a control lever 5'. Also, the scanning plate 1' has a long groove 1'a.
, 1'a' on a fixed substrate (not shown).
/, 1, 1/d/, and the bar 5' is rotatable about the bin s'by on the fixed base plate, and a biasing force is applied in the counterclockwise direction by a spring 5'e. ing. The control lever 5' has a locking tooth 5'a.

When the electromagnet 6' is demagnetized, the iron piece 6'a is separated, and the locking lever 7' is rotated to the right by the spring 7/a around the pin 7' on the fixed base plate, and the claw 7' is rotated to the right. c engages with the locking tooth portion 51a, and the control lever 5' is locked. Distance ring 2' has a photographic lens attached and is located at the original axis of the lens. The center can be rotated to the left by a spring 2'+1. However, the pin 2'θ on the distance ring 2' is the protrusion W1 of the front running plate 1υ that starts operating with the shirt release operation.
0b, the distance ring 2' does not operate until the front running plate 10 operates, that is, until the shirt release is performed. The front running plate 10 is movably attached to a bin 10d on a fixed base plate via a long groove 10ai, and is biased to the left by a spring 10c. When the front running plate 10 operates, the distance ring 2' rotates to the left, the engagement step cam 2'f engages with the end 5'd of the control lever 5', and the rotation of the distance ring 2', that is, the photographing lens, is rotated. will be stopped.

Next, the operation will be explained. When the release member (not shown) is pressed down in the pre-release state shown in Figure 2,
Immediately after that, the main switch S is closed, the step motor 5' rotates, the scanning plate 1' travels to the right in the figure, and in conjunction with this, the control lever 5' rotates by 1. do. ″
At the same time, the electromagnet 6', which was excited, attracts the iron piece 6'a and holds it in a position where it does not come into contact with the locking lever ylt and the engaging teeth 5/. At the end of arm 1', pulsed light and sound are emitted toward the subject.

On the other hand, the two-split sensor 8 receives the pulse-shaped reflected light from the object to be photographed from the light emitting element 9, and outputs the full goldfish signal when the outputs of the two sensors match. This output signal is input to the microcomputer and delay circuit to stop the entire step motor 3' for a predetermined time and to delay (B).
The energization of the electromagnet 6' is cut off by the output of the line. The locking lever 7', which has been released by attraction by the electromagnet 6', is rotated to the right by the biasing force of the spring 7'a, and its pawl 7'ck is brought into engagement with the locking portion m5/. Since the p step motor 5' is stopped by the microcomputer, the control lever 7' is also stopped.
The engagement between the locking teeth 5'a and the locking lever pawl 7'C is ensured. After this, the scanning plate 1' is moved to the step motor 3.
' may be driven to the final scannable position.

When the release member is further pressed down, a locking member (not shown) that locks the front running plate 10 is released, and the front running plate 10 runs to the left in the figure. When the end 5"d of the control lever 5' and the locking stage cam 2'f are engaged, the distance ring 2' can be rotated in the counterclockwise direction. 2' is stopped, and therefore the photographing lens is stopped at the in-focus position.

FIG. 3 is an example of an electrical circuit that controls the mechanism described above.
The active autofocus circuit 11
, a step motor drive circuit 12, a delay circuit 15, a microcomputer 15 made of a control section, and a power supply holding circuit 14.
It is composed of etc. The active autofocus circuit 11 includes a light emitting section and a light receiving section, and upon receiving a light emitting pulse signal from a microcomputer 15 (described later), a light emitting element drive circuit 11a sends a pulse signal of a constant frequency [to a light emitting element 9 such as an infrared light emitting diode]. An infrared beam that outputs and flashes at regular intervals? It is configured to emit light toward the subject, and the light receiving section includes two photodiodes 8a.
, 8b converts the infrared light reflected from the subject into an all-electric signal, and each photodiode 8a.

After the output signal from 8b is amplified to the ty+ level by the full operational amplifiers 11b and 11C, the differential amplifier 11d outputs the p difference? The signal is detected, passed through a synchronous detection circuit j1e7 that performs detection 7 times in accordance with the blinking cycle of the light emitting element 9, and integrated by an R-〇 integration circuit 11f [Reference signal M is detected by a comparator t1g
It is configured to compare with e and output a match signal at 9 points.

Is the step motor drive circuit 12 a signal? A so-called ring counter whose output terminal shifts each time a clock signal is input, and a two-phase one-one shift signal φ1 from the microcomputer 15. The step motor 3 is configured to rotate in the forward and reverse directions by switching the moving direction of the drive pulse according to the phase of φ.

The delay (b) path 16 operates after a predetermined period of time has elapsed since the coincidence signal of the active autofocus circuit 11 was input.
It is configured to output a signal to demagnetize six electromagnets. As a result, the locking operation is performed after the distance rings 2, 2' have completely stopped.

The power holding circuit 14 keeps the main switch S connected to the release button ON for a certain period of time from when the main switch S is turned on until the series of operations is completed.
The circuit is configured to supply operating power to the circuit from the battery 16 regardless of whether it is OFF or not.

The microcomputer 15 generates light emission pulses, synchronous detection signals,
and 2-phase clock signal? Main switch 8 generated and installed
．． A match signal from the active autofocus circuit 11 is connected to one end of the power supply holding circuit 14, the active autofocus circuit 11, and the output path 18 according to the operation of the autofocus circuit 11, and the other end is outputted from the microcomputer 15 at the end of the autofocus operation. The end of operation signal is connected. The output of the OR circuit 18 serves as an activation trigger for the delay circuit.

Note that reference numeral 17 in the figure indicates a distance display element r that displays the distance to the subject determined by the coincidence signal from the active autofocus circuit 11 and the two-phase clock signal for driving the motor.

By the way, how does a device configured like this work? This will be explained based on the flowchart shown in FIG. 4 and the waveform diagram shown in FIG.

When the camera release button (not shown) is fully pressed while facing the camera subject, the main switch S1 is turned on, the power supply holding circuit 14 is activated, and operating power is supplied to the device.
l This excites the electromagnet 6. The microcomputer 15 receives a two-phase clock signal φ1. It is output to the φtk motor drive circuit 12 to rotate the six step motors in the forward direction, and at the same time, the light emission pulse t is output to the active autofocus circuit 11 to irradiate an infrared beam toward the subject. As the step motor 3 rotates in the forward direction, the light emitting element 9 travels, and at the same time, the two-part sensor 8 detects an infrared beam. This two-phase clock signal φ3
．． φ is converted into a pulse signal for distance display and is counted.

In this way, when each member is driven by the step motor 3 until the focus of the photographing lens becomes appropriate for the subject distance, the active autofocus circuit 11
A match signal is output from the microcomputer 15, and the microcomputer 15, which has read it, outputs a two-phase clock signal φ1. Phase change of φ? The rotation of the step motor 3 is stopped.

The coincidence signal is also input to the delay circuit 13 via the OR circuit 18, and after a predetermined time has elapsed, a signal for demagnetizing the electromagnet 6 is output. Release the bias of the electromagnet 6 and release the locking lever pawl 7.
Lock the ratchet wheel 5 times with C. Thereafter, the step motor 3 rotates slightly again and operates in a direction to eliminate the gap between the locking lever pawl 7C and the locking tooth portion 5d of the ratchet wheel 5.

The microcomputer 15 has a total stroke time necessary for autofocus operation programmed in advance, and if a matching signal from the autofocus circuit 11 is not input within that time, the step motor 6 is stopped at the end of that time. At the same time, all trigger signals for delay activation are output to the delay circuit 15. Further, the light emission pulse is stopped at the end of the above-mentioned total stroke time.

The above operation is autofocus operation, main switch B is monitored, and main switch S1 is OFF.
L, and when the autofocus operation is completed, the step motor 3 moves in the opposite direction (B) and is pushed back to the predetermined position due to the above-mentioned mechanism, and at the same time, the power supply holding circuit 14 is turned OFF, and all power supply points to the device are turned off. .

The autofocus circuit 11 explained in the above embodiment is only an example of an active type, and when the present invention is applied, it performs distance measurement, stores the result electrically in memory, and then operates the photographing lens. Lens position signal? Is it a signal that is replaced with a pulse and stops the lens operation when it matches the value previously stored? It is something to put out. In this case as well, the lens operation stop signal 7 and the OR circuit 1 in FIG.
The above-mentioned effects can be obtained by applying human power to one end of 8, and the present invention is not limited by the autofocus method at all.

〔effect〕

As mentioned above, according to the invention, in a photographing lens or a control member thereof, the electromagnetic driving means is temporarily stopped by a distance detection signal, and during that time the photographing lens or control member is moved. Since the lens is stopped, the stopping operation of the photographing lens is ensured, and automatic focusing can be performed with higher precision.

Further, in the present invention, the locking operation 2 is performed after a certain delay time from the distance detection signal, and the effect is extremely large.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a device showing an embodiment of the invention, Fig. 2 is a block diagram of a device showing another embodiment of the invention, and Fig. 5 is a circuit diagram showing an embodiment of the control circuit. Block diagram, Section 4.5
The figures are a flowchart showing the operation of the above circuit, respectively.
and a waveform diagram. 1.1'... Scanning plate, 2.2'... Distance ring, 3.6'... Step motor, 4...
... Drive lever, 5 ... Ratchet wheel, 5
'... Control lever, 6.6'... Electromagnet, 7.7'... Locking lever, 8...
2-split sensor, 9... Light emitting element, 10...
... Front running plate, 11 ... Active autofocus circuit, 12 ... Step motor drive circuit,
13...Delay circuit, 15...Microcomputer, S,...Main switch. The above article l0

Claims (3)

[Claims] (1) A distance detecting means for detecting the distance to the subject, a distance adjusting means for adjusting the focus of the photographing lens based on a signal from the distance detecting means, and a locking mechanism for locking a series of operations of the distance adjusting means. and an electromagnetic driving means for driving the distance adjusting means, the electromagnetic driving means is stopped for a predetermined time by an output signal of the distance detecting means, and the locking means is activated within the predetermined time. A camera automatic focus adjustment device featuring: (2) Distance detection means for detecting the distance to the subject, distance adjustment means for adjusting the focus of the photographic lens based on the signal from the distance detection means, and control means for regulating the operation of the distance adjustment means. a scanning means connected to the control means to determine the amount of displacement of the control means in correlation with scanning for distance detection; a locking means for locking the control means; and a locking means for driving the scanning means. an electromagnetic drive means, wherein the electromagnetic drive means is stopped for a predetermined period of time in response to an output signal from the distance detection means, and the locking means is activated within the predetermined time period. (3) The device according to claim 1 or 2, further comprising a delay circuit for delaying the output signal of the distance detecting means, and the locking means is controlled by the output signal of the delay circuit. An automatic focusing device for a camera, characterized in that the automatic focusing device is activated.