JPS6152452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focus adjustment device, and particularly to an automatic focus adjustment device suitable for cameras and the like.

Various devices have been proposed for automatically adjusting the focus of the photographic lens of photographic cameras such as still cameras and cine cameras, and television cameras. Various devices have been improved to improve detection accuracy. Most of these conventional devices photoelectrically convert at least a part of the object using one or more photoelectric elements, detect the conversion output to detect a distance signal to the object, and then open and close the shutter, etc. It performs exposure operation. The operation of detecting the object distance, the operation of adjusting the lens to the detection distance, and the exposure operation need to be performed sequentially, and if there is wasted idle time in each operation sequence, the time will be reduced within a short time. , the final exposure operation cannot be reached, and in the case of a photographic camera, the shortcoming is that the ability to take quick pictures is impaired. On the other hand, if each of these operation sequences is performed within a short period of time, the next exposure sequence operation is initiated before the lens is completely still, resulting in a disadvantage that only a blurred image is obtained. Therefore, it is inconvenient whether the time required for each sequence operation is long or short, and moreover, it is necessary to incorporate a sequence that moves on to the next operation after an appropriate required time. An automatic focus detection device that mechanically performs the above-mentioned sequence has already been proposed for small cameras. In accordance with the detected information, the photographing lens is repeatedly moved and the lens is stopped by an electromagnet at a desired position, and in the third step, the shutter release is performed by an electromagnet interlocking mechanism. be. In such a known device, once the device is activated, the sequence progresses to the final step, so that each operation appears to be performed in a seemingly satisfactory state.
There is a risk that you will not notice that a failure has occurred until the very end, and you will fail.

In particular, there is a high risk that the user may continue shooting without noticing that the battery, which is essential to such a device, is exhausted. Such a drawback could be solved by, for example, providing a battery checker circuit and displaying a warning lamp in the viewfinder to warn when the battery voltage drops, but it may be overlooked and the function may not be sufficient. I can't.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional apparatus, and its characteristic feature is an automatic focusing system configured to execute each operation step by an electronic sequence circuit after starting a sequence. The purpose is to provide a detection device.

Other features of the invention include inserting a power supply voltage check step into the electronic sequence circuit;
In this step, a check operation is performed on the power supply voltage, and if a voltage drop is detected, the step does not proceed to the exposure step.

Other features of the present invention will become apparent from specific embodiments of the present invention described in detail below.

Specific examples of the present invention will be described below.

Figures 1 to 5 show configuration examples when the present invention is applied to a still camera, and basically include the mechanism section of the automatic focus adjustment device, the detection circuit, the sequence control circuit, the shutter mechanism section, and the like. It consists of a control circuit. Each part will be explained below.

(A) Automatic focus adjustment device 1 Mechanism section (see Fig. 1) Fig. 1 shows only the structure near the lens with the camera main body section omitted.
1 is a photographing lens; 2 is a lens barrel that supports the lens 1; 2a is a cam formed on the rear end wall of the lens barrel 2;
3 is the optical axis of the lens 2, 4 is a ratchet tooth provided on the circumference of the lens barrel 2, and 5 is held in the center so as to be swingable by a shaft 5a which is pivotally supported by the camera body frame (not shown). It shows a stop pawl that locks the ratchet teeth at the tip of the pawl. The stop pawl 5 is always biased in the locking direction by a spring 7, but a bent portion is formed at the tip of the pawl, and the bent portion is attracted by the magnetic pole when the electromagnet 6 is energized. , to release the lock. 8 has its rear end interlocked with an interlocking pin 13 installed on the lower shaft of the release button 12 of the camera, and its center is swingably held by a frame (not shown).
The tip of the locking lever engages with the protrusion 9 on the lens barrel 2 when it is rolled up, and 10 represents a spring that always biases the locking lever 8 in the locking direction. The center portion 14a of the stopper 14 is swingably held by a pivot pin (not shown), and its tip bent portion is configured to be a set lever that can be engaged with the rear end of the stop pawl 5. is urged in the counterclockwise direction by a spring 15 and is extended by an implant pin 13 so as to interlock with the release button shaft. The implanted pin 13 is implanted at a position where it becomes engaged with each of the levers 8 and 14 when the release button 12 is pressed to the second stage. 16 is set to the open state by pin 13 before button 12 is started, and button 1
A power switch 17, which will be described later, is closed by the first step of pressing 2, and a lens start signal (hereinafter referred to as 17) which is opened and closed by a pin 24 installed on the lens barrel 2.
When the lens barrel is set to the initial state after being rolled up by the formation switch (referred to as the LEST signal), it is opened by the pin 24, and immediately after the lens barrel 2 is started, it is closed. 18, lens barrel 2 is 5
When it is extended to the m position, it is a 5m switch that is turned on by the lens barrel installation pin. In addition, lens barrel 2
When a spring 101 is suspended on a pin 102 fixed to the rear end surface, the tip of the lever 103 rotates the pin 102 via the wind-up lever 27 and the wind-up lever 103 when the camera is rolled up. As a result, the lens is charged and rotated to the right by the charging force at the time of release. The lens barrel 2 moves forward and backward in the direction of the optical axis 3 when the lens barrel 2 itself rotates due to a helicoid mechanism (not shown), and when the lens barrel 2 is fully rolled up as shown in the first figure, the lens 1
is set close to the subject. When the lens barrel 2 is rotated to the right by the force of the spring 101, the lens barrel 2 is extended in the direction of the optical axis, and the lens 1 is displaced toward the infinity set position.

Reference numeral 21b is a pin that slides into contact with the cam 2a, and is implanted at the tip of the scanning lever 21. Scan lever 2
1 is pivotally supported at its central portion 21a on a camera frame (not shown) so as to be able to freely swing, and a light emitting diode 20 for emitting infrared light is supported at a bent portion at the rear end.

25 is a projection lens, and a light emitting diode 20
A light emitting diode 20 is placed at the focal point.

When the lens barrel 2 is extended from a close range, the cam 2a causes the light emitted from the light emitting diode 20 to be scanned by the lens 25 from the close range to infinity in accordance with the set position of the lens barrel 2. be done. Reference numeral 23 denotes a silicon photocell (hereinafter referred to as SPC) having sensitivity to the wavelength light emitted by the light emitting diode 20; 26 a light receiving lens;
3 is positioned and fixed so that the light receiving direction thereof is approximately parallel to the optical axis 3.

As will be described later, by pressing the release button 12, each lever 8, 14 is unlocked, and the lens barrel 2 is released.
When the SPC 20 is extended, when the light emitted from the light emitting diode 20 is directed from a close distance to the object to be scanned toward infinity, the SPC 20 receives the reflected light from the object. Then, the output of the SPC 20 becomes maximum, the electromagnet 6 is de-energized by a detection circuit to be described later, and the stop pawl 5 bites into the ratchet teeth to stop the lens barrel 2.

2. Automatic focus detection circuit (see FIG. 2) The detection circuit shown in FIG. 2 has roughly the following detection mode due to the limitations of the light emitting diode.

(a) When the subject is placed within the distance where the projected light from the light emitting diode reaches with the desired intensity, for example within 5 m, the extreme value of SPC20 is detected at the lens extension position within 5 m as described above. Therefore, the lens is adjusted based on this detection output, that is, at each position corresponding to the subject position.

(b) When the subject is placed further away than in (a),
The level of light reflected from the object based on the projected light is often lower than the level of noise light outside the projected light, so there is a risk that noise light may be mistakenly determined as detection light. In the second illustrated detection circuit, 5
The level of reflected light at a position near m is detected, and if the level is higher than a predetermined level, the object is near 5 m, so the lens is stopped extending at that point and set at the 5 m position. On the other hand, if the reflected light level is lower than the predetermined level, since the subject is located further away, the lens is extended to a position intermediate between the infinity position and the 5 m position, for example, the 16 m position. The lenses are set at the same position. When set at this position, there is a depth of field both in the 5 m direction and in the infinity direction due to cooperation with the diaphragm device, so the image can be photographed with approximately constant sharpness no matter where the subject is located.

The details of the detection circuit that implements the above functions will be described above.

Figure 2 basically consists of an oscillation divider circuit A, a light emitting diode drive circuit B, an SPC amplification circuit C, a sample hold circuit D, a peak detection circuit E, a level detector, and an electromagnet control circuit F. .

The oscillation frequency dividing circuit A starts being supplied with power (Vcc) from the battery by the switch 16 which is closed by the first press of the button 12. Capacitor C and resistor R ₁ - connected to inverting circuit I ₁ - I ₃ and feedback circuit
It is composed of R ₂ , VR, and a frequency dividing circuit CD (for example, the counter divider CD4017 manufactured by RCA), and the oscillation signal of a predetermined frequency is divided by the frequency dividing circuit CD.
Formed as CLK ₁ to _{CLK 3} .

The drive circuit B is composed of a constant voltage circuit SV, an operational amplifier A13 for voltage level detection, a voltage set resistor VR ₂ , and transistors Tr ₁ to _{Tr 3} .
The conduction of Tr ₂ is controlled by the frequency divided signal CLK ₁ and the shutter release operation inhibit signal _SH1 , which will be described later, via an OR gate CRc. The diode 20 is excited and the diode 20 is periodically blinked at a constant frequency, for example, 10 KHz. Since the transistor Tr ₃ is opened when the lens barrel 2 is set at the initial position, it becomes conductive and the diode 20 is kept in the off state via the transistor Tr ₁ to make the transistor Tr ₂ conductive.

The amplification circuit C connects the photodetector diode SPC23 to its input, amplifies it through the operational amplifier _A1 , and then applies the SPC23 output to the sample and hold circuit D input through a capacitor that constitutes a high-pass filter circuit. . A low-pass filter is connected to the feedback circuit of the amplifier circuit C, and has an amplifier for a higher frequency component signal than the blinking period of the light emitting diode 20, which will be described later, for example, a signal component of 10 KHz or less. /N ratio is improved. Sample and hold circuit D is the frequency divider circuit CD output signal
Analog switches AS ₁ , AS _{2 whose conduction is controlled by CLK 2 , CLK 3 , sample} and hold capacitors CH 1 , CH 2 , CH 3 , operational amplifiers A ₃ to _{A 9} ,
It consists of resistors _R5 to _R13 , _VR3 , and a smoothing capacitor CL. Frequency division output CLK ₂ of frequency division circuit CD,
Since CLK ₃ is a signal with a phase difference of 180°, analog switches AS ₁ and AS ₂ are connected to light emitting diodes 20.
It becomes conductive alternately in synchronization with the lighting and extinguishing of the
The amplified output of the SPC23 is subdivided in a time division manner, and the capacitors CH ₁ and CH ₂ are held. Therefore, from the output of the operational amplifier _A5 , only the change due to the temporal change in the output of the SPC23 is taken out and smoothed by the resistor _R8 and the capacitor CL. capacitor
CH ₃ gradually holds the increasing and fluctuating amplified signal by the action of diode D ₃ , and when the SPC23 output change passes the peak and goes from the increasing direction to the decreasing direction, the resistance increases.
Discharge starts with a certain discharge time constant due to the discharge path _R10 , but by setting a large time constant, the peak value is maintained for about a certain period of time. Variable resistor VR ₃ divides the amplified output of operational amplifier A ₈ and then applies it to the non-inverting input of operational amplifier A ₉ , but the output of operational amplifier _{A 6 is} applied to the inverting input of operational amplifier A 9. . The SPC23 output of the operational amplifier _A6 increases, and after passing the peak value, it then fluctuates in the decreasing direction.In order to reproduce this changing signal as a DC component, the time constant of the resistor _R10 and capacitor _CH3 is If it is sufficiently large as described above, both input levels of the operational amplifier A ₉ will match after a certain period of time when the SPC 23 output passes the peak value. During this time, the inverting input level of operational amplifier A ₉ is high, so electromagnet 6 continues to be excited via operational amplifier A ₁₀ and transistor Tr ₃ , and after both inputs of operational amplifier A ₉ match, electromagnet 6 is de-energized. , locks the lens barrel 2. As mentioned above, the electromagnet 6 stops the lens barrel after a certain time delay after the SPC 23 output reaches its peak value, but the initial movement of the lens barrel is delayed by this delay time using a delay mechanism etc. It goes without saying that it would be better to do something like this, but this point is not directly related to the present invention and will therefore be omitted. In the circuit F, the signal level detection section includes operational amplifiers A ₁₁ and A ₁₂ and transistors Tr ₄ and Tr ₅ as basic elements. A variable resistor VR ₅ for setting a predetermined level is connected to the non-inverting input of the operational amplifier A ₁₁ , and a comparison is made with the capacitor CL level. If the extended position of the lens is within 5 m, the switch 18 is in the off state, so a high level signal is applied to the input of the operational amplifier _A12 via the diode _D2 , turning the transistor _Tr4 on. When the lens barrel is extended to a position of 5 m, the switch 18 is turned on, but if the signal level of the capacitor CL is higher than the set level of the resistor VR5, the transistor Tr ₄ is turned on via the diode D ₁ and the operational amplifier A ₁₂ . , the electromagnet 6 is forced into a de-energized state. On the other hand, when the signal level is low, the transistor Tr ₄ remains off and the electromagnet 6 continues to be excited, so that the lens barrel is extended until it stops at an infinite position.

(B) Sequence control circuit (see Figure 3) In Figure 3, G is a power supply voltage detection circuit and is an operational amplifier A that compares the constant voltage obtained by the constant voltage diode and the voltage of the resistor voltage divider _circuit . When the Vcc voltage is above a predetermined value, a high level signal is formed, and when it is below a predetermined value, a low level signal is formed. FF1 and FF2 are D-type flip-flops for status determination, and CD4013 manufactured by RCA, for example, is used. _I5 to _I7 are inverting circuits, AND1 to AND3 are AND circuits, OR1 to OR3 are logical sum circuits, _C1 is a counter such as RCA CD4020, and the _ClK2 signal is applied to the clock input (clock). The reset input R is released, counting starts, and a high level signal is obtained at the output terminal Q8 after a predetermined time.
CR and RS indicate capacitors and resistors for reset signal formation. Inverting circuit I ₆ input is the second
The 5 signal obtained from the diode D2 _side terminal of the switch 18 in the figure is connected to the signal terminal which becomes high level until the lens is extended to 5 m and indicates that the distance has not yet reached 5 m. On the other hand, inverting circuit I ₄
A signal obtained from the terminal of the switch 17 connected to the base of the transistor _Tr3 (FIG. 2) is applied to the input of the transistor Tr3.

Based on the above configuration, when the switch 16 is turned on by pressing the first stage of the release button 12 and the power supply voltage Vcc is applied, a high level pulse is generated by the reset circuits CR and Rs, and is applied to the flip-flops FF1 and FF2. It is reset and set to the initial state. At this time, when the release button 12 is pressed and Vcc is supplied before the lens barrel 2 starts retraction operation, the signal changes from low level to high level, so the terminal of flip-flop FF1 changes from high level to high level. change to a lower level. Similarly, the Q terminal of flip-flop FF2 becomes high level. As a result, the power supply voltage Vcc
If is high enough, a low level signal ( _I5 output and FF1 terminal) is applied to the input of the AND ₃ circuit,
Its output is low level, the other flip-flop FF
Since the Q terminal output of No. 2 is at a high level, the OR3 circuit output is at a high level, and the SHI signal output from the _I5 circuit output is at a low level. (As long as the SHI signal remains at a low level, the shutter will not be released, as will be described later).

At this time, even if the G circuit output becomes low level, the SHI signal remains at low level as long as the terminal of flip-flop FF1 is at low level. When the release button 12 is further pressed to start extending the lens barrel 2, the signal becomes low level. As a result, both flip-flops FF1 and FF2 are inverted, the terminal of FF1 goes from low level to high level, and the Q terminal of FF2 goes from low level to high level. Accordingly, the OR3 circuit output is at a high level, and as a result, the SHI signal is kept at a lower level than the _I5 circuit, and shutter release is prohibited. When a peak inversion signal (signal) is output from the output of operational amplifier _A10 , the signal changes from high level to low level, so flip-flop FF2 is reset again and the Q terminal becomes low level. As a result
The _I5 circuit output SHI signal becomes high level, and when a separately provided timer time elapses as described later, the shutter opens.

On the other hand, when the peak signal is not obtained and the lens barrel rotates and the switch 18 is closed, the 5 signal becomes a low level, and the signal, that is, the _A11 circuit output is at a low level (when the subject is near 5 m).
Since the output of the NAND circuit NAND1 remains at a high level, the counter _C1 is maintained in the reset state.
On the other hand, when the lens barrel reaches the 5m position and the 5 signal becomes low level, one input of the AND1 circuit becomes high level by the inverting circuit _I6 . At this time, since the A11 output is low level, the AND1 circuit output becomes high level from the inverting circuit _I6 , and is passed through the AND2 circuit to the flip-flop FF.
2 is reset and the SHI signal becomes high level, so the process moves to the shutter release step. During this time, as soon as the switch 18 is closed, the electromagnet 6 locks the lens barrel at the 5 m position due to A12 and _Tr4 . If the subject is at infinity (not near 5m), signal (A11 output)
Since is at a high level, the AND1 circuit output is at a low level. On the other hand, as soon as the 5 signal is output from the counter _C1 , the NAND1 circuit output becomes low level, so the reset state is released and counting starts, and when a high level signal is obtained from the Q8 output after a predetermined period of time, the flip-flop Since FF2 is reset, the SHI signal becomes high level at this time, and the next shutter release operation begins. After the time measured by the counter C ₁ until the SHI signal becomes high level, the output from the terminal Q8 is transferred to the transistor Tr ₅ (second
(Fig.), the electromagnet 6 is de-energized, and the lens barrel is locked at an intermediate position between the infinity position and the 5 m position, for example, the 16 m position.

When the SHI signal becomes high level and moves to the shutter release step, the transistor Tr ₂ is turned on via the CRc circuit (Fig. 2).
Tr ₁ is turned off, and the light emitting diode 20 is turned off, thereby preventing unnecessary power loss.

If the power supply voltage is not high enough when the lens is extended and set at a 5m position, operational amplifier _A14
Since the output becomes low level, the SHI signal remains low level and does not move to the next step, but when the peak signal is detected, flip-flop FF2
is reset, allowing the SHI signal to go high. The reason for this is that although the light emitting diode 20 consumes quite a large amount of power, it is predicted that there is still sufficient power remaining when peak detection is obtained, so in this case, the voltage detection step is performed. Without any hesitation, we move on to the next step.

(C) Shutter control circuit and mechanism (see Figures 4 and 5) In Figure 4, 110 and 111 are resistors that form a time constant circuit with a capacitor 112, and resistor 110 is set to the self-timer seconds. Resistor 111 is a resistor that forms the sequence transition time, _S2 is a release interlocking switch that is opened when the second step of the release button 12 is pressed, and _S5 is turned on when the self-timer mode is set to form the self-timer time. Mode switch, 113 is a semiconductor switching circuit, 115 is an AND circuit that takes an AND input with the SHI signal and the switching circuit, Mg ₁ is a magnet for starting the shutter opening operation,
Reference numeral 121 indicates a capacitor for storing magnetic starting energy, and reference numerals 116, 120, and 118 indicate protective resistance diodes. 123 is a CDS that receives the subject light, 124 is a time constant capacitor, _S4 is a short-circuit switch that is opened when the shutter starts to open, 12
5 is a switching circuit, and Mg ₂ is a shutter closing magnet. As the cds 123 to Mg ₂ may be a known shutter circuit, the details thereof will be omitted.

Reference numerals 127 and 128 indicate batteries that supply the power supply voltage Vcc. FIG. 5 shows a shutter mechanism used in combination with the circuit of FIG.
02 is a shutter blade having openings O ₁ and O ₂ respectively, and forming a shutter opening by the relative movement of the shutter blades;
Reference numeral 03 denotes a drive lever in which pins 204 and 205 are installed to fit into slots formed in the shutter blades 201 and 202, and this lever has a pivot pin 206 provided at its center that is loosely attached to a fixed frame (not shown). are doing. There are openings in the shutter blades 201 and 202.
Water droplet-shaped small apertures AP ₁ and AP ₂ are provided on the light receiving _front surface _of the CDS 123 in parallel to O ₁ and O ₂ .
An aperture corresponding to the photographing aperture formed by the small aperture is formed by the same small aperture.

The shutter blades 201 and 202 are guided by the guide pin 207
~210 has a straight slot that fits into it,
An opening spring 211 suspended from the lever 203 drives the shutter blades 201 and 202 relative to each other at the same time.

Reference numeral 212 designates a locking lever that releases the tension of the tip of the lever 203 by attraction by the magnet Mg ₁ , and is biased by a spring 213 in the clockwise rotation direction, and is connected to the tip of the lever 203 at the bent portion 212a. A sliding plate, which will be described later, is locked by the extension portion 202b. 2
Reference numeral 13 indicates a pivot pin at the rear end of the locking lever, and reference numeral 214 indicates a stopper pin.

Reference numeral 216 designates a sliding plate that provides a driving force for closing the shutter, and has slots that slide linearly by guide pins 217 and 218, and is biased by a spring 219. The sliding plate 216 is the tension lever 22
A locking portion 216a that engages with the bent portion 220a of the lever 220 to lock the sliding plate 216 at the charge position, and a transfer end 216b that presses the adsorption portion 220b of the lever 220 against the magnet Mg ₂ during winding up. , a bending portion 21 that engages with one end of the interlocking lever 223 of the winding lever 27 to charge the sliding plate during winding up;
6c, and has an engaging portion 216d for engaging with the locking lever 202.

Note that the tension lever 220 is operated by the force of the spring 222.
It is spring-biased in the counterclockwise direction, and is configured such that by the rolling-up operation, the transfer end 216b also presses a portion of the lever 220 against the spring 222 to engage with the locking portion 216a.

Operations based on each of the configurations described above will now be described with reference to the flowchart of FIG. When the winding lever 27 is rolled up, a known mechanism (not shown) causes the lever 223 to swing against the spring 227 at the same time as the film is rolled up, and the sliding plate 216 is moved to the fifth illustrated position, and the locking lever 212 Lock it at. The winding lever 27 is simultaneously connected to the first illustrated gear,
Due to the wrap mechanism, the drive spring 10 of the lens barrel 2
1, and the lens barrel 2 is locked in the closest position by the locking lever 8.

When the release button 12 is pressed in this charged state, the switch 16 is closed by the first press, and Vcc voltage is applied from the battery 127 in FIG. 4 to each circuit section. At this time, the transistor _T6 is turned on by the output of the amplifier _A10 , the electromagnet 6 is excited, and the stop pawl 5 is separated from the ratchet tooth 4.

If winding is completed, switch 17 is pin 2
4, the SHI signal is at a low level (when the power supply voltage is high) as described above, and this signal is sent to the magnet _Mg1 . However, if the lens barrel is not at the initial position for some reason, the switch 17 is in the on state, and the signal in FIG. When the signal is high), the AND ₃ circuit becomes low level, so the SHI signal becomes high level due to the I ₅ circuit. In this case, when the release button is further pressed, the switch _S2 opens and the switching circuit 113 opens after a time set by the timer circuits 110, 111, 112, for example, 100ms.
When a high level signal is output from the SHI signal, the magnet Mg ₁ is excited and the shutter is released. Therefore, in this case, the photographing operation is performed without performing the automatic focus adjustment operation.

Except for such cases, when the release button 12 is further pressed, the locking lever 8 is released, and the lens barrel 2 starts rotating to the right by the force of the spring 101. As a result, switch 17 closes, transistor Tr ₃ turns off, and transistor Tr ₂
is periodically turned on and off by the frequency-divided signal CLK ₁ , so it starts lighting periodically. At the same time, the scanning lever 21 uses the cam part 2a to project the projection light of the light emitting diode 20 from a position close to the subject toward infinity. When the subject is within 5 m, a peak signal is obtained as described above, and the SHI signal is transmitted. High level. As a result, the SHI signal causes the transistor to
Since Tr ₂ is kept on, the diode 20
goes out. The switch _S2 in Fig. 4 starts timing by pressing the second step of the release button 12, and approximately
After 100 msec has elapsed, the AND circuit 115
Magnet Mg ₁ is energized. The time it takes for the lens barrel to reach the infinity position after starting is approximately
When set to about 80msec, the time constant circuit 110,1
11,112 after the timer elapses for one hour, that is, approximately
After 100 msec has elapsed, the lens barrel will be completely stationary. When the magnet Mg ₁ is excited, the tension of the lever 212 is released, so the drive lever 203 is rotated to the right by the force of the spring 211, and in order to move the shutter blades 201 and 202 relative to each other, the openings O ₁ and O ₂ are opened. The opening gradually opens in accordance with the amount of weight. At the same time, the front surface of the photodetector CDS also has a corresponding aperture.

The switch is activated by the opening operation of the shutter blade 202.
Since S ₄ is opened, magnet Mg ₂ is deenergized after a time determined by CDS and capacitor 124. As a result, the tension of the sliding plate 216 is released, and the engaging portion 216d of the sliding plate rotates the drive lever 203 to the left due to the force of the spring 219, thereby moving the shutter blade relative to each other again, closing the shutter blade, and exposing the shutter blade. ends.

If the subject is close to 5m, depending on whether the signal level of the SPC23 output is sufficient, the camera will immediately move to 5m.
Lock the lens barrel in position or use the counter
The lens barrel is extended for the timer time determined by C ₁ , and the timer time is completed. There is a difference in whether the lens barrel is locked at the infinity position, but when the G circuit output in Figure 4 is at a low level, SHI
Since the signal remains at a low level, there is no transition to the shutter release stroke, and at that point all operations are stopped. At this time, the 6th
As shown in the flow shown by the dotted line on the right side of the figure, it is necessary to release the release button and stop the power supply Vcc before replacing the battery.

When the power supply voltage drops and the lens barrel is not set to the initial position for some reason, the light emitting diode 20 is in the power supply state, but similarly
The SHI signal remains at a low level, all operations stop, and the shutter release process does not proceed.

In this case as well, as shown in the dotted line flow on the left side of Figure 6,
It is necessary to replace the battery and perform the winding operation again.

As mentioned above, the lens barrel starts to start by pressing the second step of the release button, but at the same time, the timer circuit also starts timing, and when a peak value is detected or a 5m signal, etc., the lens barrel is locked and the sequence circuit starts. Even if the state is shifted to the next shutter release stroke, the actual release will not be performed until the timer circuit completes timing, so the release will be performed after the lens barrel has surely come to rest.

As described above, in the present invention, the electronic sequence circuit is started by the startup operation, enters the next step when automatic focus is detected, and determines whether to proceed to the next step by checking the power supply voltage. I made the decision and moved on to the next exposure step.
The electronic sequence circuit, which has the function of determining whether each step operation has operated reliably or is in a state where it can operate reliably, always checks whether it is ready for operation, but the step operations are performed sequentially, resulting in failure. It is extremely effective and can be expected to operate without any problems.

In the above embodiments of the present invention, the active focus detection method using light emitting diodes was described, but the present invention is not limited to this, and the present invention is not limited to this. Of course, it is possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main parts of an automatic focus adjustment device for a camera to which the present invention is applied. FIG. 2 shows a focus detection circuit applied to the device shown in FIG. FIG. 3 is a sequence control circuit applied to the device shown in the first figure. FIG. 4 is an electrical circuit diagram of an electric shutter used in conjunction with the device shown in the first diagram. FIG. 5 is a configuration diagram of a shutter mechanism applied to the circuit shown in the fourth diagram. FIG. 6 shows flowcharts for explaining the operation. G...Power supply voltage detection circuit, FF1, FF2...Discrimination flip-flop, _C1 ...Counter, AND1~
AND3...AND circuit, I ₂ ~ I ₇ ... Inverting circuit, OR ₁ ~
OR ₅ ...Order circuit.

Claims (1)

[Claims] 1. A photographic optical system that changes the focus position by movement, a starting means that moves the photographic optical system from an initial position in response to a shutter release operation, and a focusing signal that is sent when the photographic optical system reaches the in-focus position. a predetermined position detection means for outputting a predetermined position arrival signal when the photographic optical system reaches a predetermined position; and a predetermined position detection means for outputting the predetermined position arrival signal. a gate for starting an exposure operation in response to the shutter release operation; and a gate for detecting whether or not the photographing optical system is set at the initial position in response to the shutter release operation, before the activation means operates; 1. A camera comprising: initial position detection means for shifting the exposure operation without operating the activation means when the exposure means is not set at the initial position.