JPS5830613A - Distance measuring device - Google Patents

Abstract

PURPOSE:To obtain the measuring accuracy similar to the accuracy in the photographing in the daylight, by enlarging an angle of a distance measuring light receiving element, which observes an object to be photographed, at the time of flash light photographing, in comparison with the angle at the daylight photographing, thereby enlarging the distance measuring region. CONSTITUTION:The light receiving element 1 is used at the daylight photographing and has sensitivity in an infrared region. The light receiving element 225 is used at the flash light photographing and has the sensitivity in the infrared region. The light receiving elements 1 abd 225 are selectively used depending on the photographing mode. A light receiving lens 201 is provided in front of a half mirror 224 that is provided in a light receiving path of the light receiving elements 1 and 2. A light emitting device 103 is fixed to one end of a fork shaped scanning lever 203 which is guided and moved by a cam. A roller 207, which is slidably contacted with the cam, is provided at the other end.

Description

[Detailed description of the invention] The present invention relates to a distance measuring device.

Conventionally, various distance measuring devices for measuring the distance of a target object have been proposed.

Broadly speaking, these distance measuring devices are able to convert the reflected light from the object into an electrical signal without using any irradiation light on the object to be ranged, and calculate the maximum value of the electrical signal output. The so-called passive method detects and measures the distance, and the other is the passive method, in which a projector is installed on the camera side, and the object is scanned while being illuminated with a beam of light from the projector, and the maximum value of the beam reflected from the object is measured. It can be divided into the so-called active method, which performs detection and distance measurement.

For example, in the latter active type distance measuring device, the distance measuring operation is performed by scanning a so-called zone mark that indicates the range illuminated by the beam from the above-mentioned projector installed in the finder (hereinafter referred to as the scanning area). This is done by matching the .

Even with such a distance measuring device, if the object is placed under high brightness or has high brightness, for example during the daytime, the distance measuring device can accurately aim at the object. The distance measurement accuracy is high, but if the object is in a dark place and its own brightness is low, the object visible in the finder will be dark and the zone mark mentioned above will also be dark. This makes it very difficult to match the object, and the beam from the projector often cannot accurately measure the distance from the object to be measured.

In addition, even with the former passive type distance measuring device, the same problem has arisen since it is not possible to accurately aim at the object to be measured during distance measuring operations at night as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a distance measuring device capable of performing one-time distance measurement similar to the case of high brightness even when the brightness around or on the object is low.

An embodiment of the present invention will be described below with reference to the drawings.

Figure vJ1 is a configuration diagram of the main parts of a camera having a distance measuring device to which the present invention is applied, in which 1 is a light receiving element that is used during high brightness history, that is, daylight photography, and has sensitivity in the infrared region, and 225 is an object. The light-receiving elements 1 and 225 are used at low-luminance times when the surroundings are dark and the brightness of the object itself is low, that is, during flash photography.The light-receiving elements are sensitive to the infrared region, and the light-receiving elements 1 and 225 are selectively used depending on the photographing mode. 224 is a light-receiving lens disposed in front of the half mirror 12 provided in the light-receiving optical complex of the light-receiving elements 1 and 2; 203 is a light-receiving lens that is pivotally supported by a shaft 205 and is guided by a cam (not shown); A two-pronged scanning lever that moves, and one end of the lever 203 has a second
The illustrated light emitting diode 103 is fixed, and the other end is provided with a roller 207 that contacts the aforementioned cam (not illustrated).

209 is a spring that gives the scanning lever 203 a clockwise swinging habit; 211 is a light projection lens disposed in front of the light emitting diode 103; 213 is a photographic lens barrel having a photographic lens optical system therein; 215 is a mirror. Nine drive springs are suspended on the cylinder 213; 217 is a locking claw attached to the outer periphery of the wire portion 213; 219 is a claw-shaped tip;
Reference numeral 21 denotes a stop claw which is always given a clockwise swinging habit; 223 is a shaft for the stop claw 219; and 101 is a stop claw for holding the stop claw 219 in the first state in the initial state. It's a magnet.

FIG. 1A is a diagram for explaining the operation of the portion related to the light receiving element in FIG. 1.

FIG. 1B is an external view of the camera having the distance measuring mechanism shown in FIG.
The flashlight emitting unit 302 is in a stored state and is a flashlight emitting unit that protrudes above the main body 301 and is in a fixed position when in good condition. Reference numeral 303 is an operation knob for shifting the light emitting section in the retracted state to the protruding state. When the knob is manually slid to the right, the flash light emitting unit 302 is configured to pop out to the position of 302 people. 304 is a film winding lever, and 213 is the lens barrel shown in FIG. 1 above. 307 is a finder, 308 is a light receiving lens 20 shown in FIG.
1, a light receiving window provided on the front surface of 1; 306 is a light projecting lens 21;
This is a floodlight window provided in the front of 1.

FIG. 1C is a perspective view showing the external appearance of the flashlight emitting unit 302 built into the camera shown in FIG. 1B, and the operation unit 303.
, shows the relationship between changeover switches, etc. The operating section 303 has an arm 310 rotatably supported by a fulcrum 308 provided on the camera body, and is biased clockwise by a spring 311. When using the flashlight emitting unit, the flashlight emitting unit 302 is connected to the spring 30 disposed between the camera body and the flashlight emitting unit 302.
9 and is pushed down into the camera body, and the operation knob 3
The end 310a of the arm 310 of 03 is the strobe body 3.
It is engaged with a groove 302b provided at 02 and held at the position indicated by the solid line 302 in the diagram @lB.

When in this position, it is in contact with the lower end of the flash light emitting section 302. When the operating knob 303 is manually operated in the direction of the arrow from this state, the end 310m of the arm 310 comes off the groove 302b of the flash device 302. At this time, the protrusion 302m of the flash light emitting section 302 is switched to the 4th protrusion.

That is, when the flashlight emitting section 302 is in the state of being pushed into the main body, the switch Sl is contacted as described above.

Also, manually move the operation knob 303 to the right to make the flash light emitting part pop out to the position of 302 people, and when running, press the switch S.
1 is in good condition with the contact pieces 81c and 81a in contact as described above, so the first light receiving element 225 shown in FIGS. 1 and 2 is selected. That is, the configuration is such that the light receiving element 225 is used during flash photography, and the light receiving element 1 is used during daylight photography. The light receiving element 1 and the light receiving element 225 are constructed as shown in FIG. 1A. The light receiving element 1 receives the light from the light emitting diode 103 for projecting light via the light receiving lens 201 and the half mirror 224, and the light receiving element 225 receives the light from the light receiving lens 201, and in the case of the above-mentioned /S-filler optical element l. D2, and in the case of the light receiving element 225, it is Dl, and DI>D
It is configured to be 2. Therefore, the optical path length from the center of the light-receiving lens to the light-receiving element surface is longer up to the light-receiving element 1 than to the light-receiving element 225. The angle (dashed line) from which you can see is thicker. In other words, in flash photography used when ambient light is insufficient, the angle at which the light receiving element 225 looks at the subject (also referred to as the scanning area) is the same as the angle during daylight photography (also referred to as the scanning area).
It is configured to be thicker.

Fig. 2 is an electric circuit connection diagram of the camera distance measuring device used in Fig. 1.
A light-receiving circuit that converts light from 03 into an electrical signal, which includes light-receiving elements 1 and 225 that are multiplied by MAR calculation at the light-receiving port, resistors 5 and 7 connected to the feedback path of the amplifier 3, and a connection point between the resistors. One end is connected to a resistor 9, and the other end is connected to a resistor 9.The resistance values of these resistors 5 and 7.9 and the capacity of the capacitor 11 are determined by the blinking of the light emitting diode 103. A value is selected that increases the gain of signal frequencies near the period and suppresses the gain of frequencies lower than this frequency.

The part surrounded by the point iIB is an amplification circuit that amplifies the input signal near the frequency, and the amplifier IIIBfi is connected to the capacitor 13 and the resistor 15 constituting the bypass filter, as well as to the output terminal of the skeleton bypass filter. It has an operational amplifier 17 having a non-inverting input. Further, the width increasing circuit B further has the above-mentioned width increasing circuit B! Resistor 19 connected to the return path of 17
It also has a resistor 21 connected to a connection point between the resistor 19 and the inverting input terminal of the operational amplifier 17. The part surrounded by the dotted line C is a synchronous detection circuit for sampling and holding the output signal from the amplification circuit B in response to a synchronization signal, which will be described later.

For example, the analog switch 23 and 25 are formed of bipolar analog switches, and the analog switch 2
3, 25, two AND gates 27.29 having output ends connected to the control electrodes 3, 25, a resistor 31.33, a voltage holding capacitor 35.37, and a follower connected to the output end of the capacitor 35. - circuit MI39 and a second follower circuit @4 connected to the output terminal of the capacitor 37
1, an operational amplifier 45 having an inverting input terminal connected to the output terminal of the follower circuit j641 via a resistor 43, and a resistor 47 connected to the feedback path of the amplifier 45. ing. The circuit formed by 43, 45, and 47 forms an inverter that inverts the level of the output signal of the follower circuit 41 with respect to the calculation reference level KVC with a gain of 1. The part surrounded by a dotted line is a pseudo compression circuit that amplifies the low Pel output signal and compresses the high Pel output signal of the output signal of the synchronous detection circuit C. are a resistor 49.51 for determining a reference potential, an operational amplifier 53 having a non-inverting input terminal connected to an output terminal of a voltage dividing circuit formed by the resistor 49.51, and the amplifier 53. P having a resistor 55 connected between the output terminal and the inverting input terminal of the P amplifier and an emitter connected to the output terminal of the amplifier 53 via a resistor 57.
NP)j resistor 59 and resistor 61°63.65.

The part recessed by the dotted line E is a low-pass filter connected to the output end of the pseudo compression circuit in order to remove noise components asynchronous to the synchronization signal and the synchronization signal component. A portion surrounded by a dotted line F, which includes a resistor 67 and a capacitor 69 connected between the resistor 67 and the ground, is a peak detection circuit to be described later when the output signal of the low-pass filter E is below a predetermined value. A peak detection prohibition circuit for prohibiting the operation of G, the prohibition circuit F includes a resistor 71.73 that determines a reference potential,
a comparator 75 having a first input connected to the output of a voltage dividing circuit formed by 1.73 and a second input connected to the output of the low-pass filter E; and a Nant gate 77. In the peak detection circuit, an operational amplifier 79 having a non-inverting input terminal connected to the output terminal of the V-bus filter; , a diode 81 having an anode connected to the output terminal of the amplifier 79, and a capacitor 85 connected to the cathode of the diode 81 via a resistor 83 and to the inverting input terminal of the amplifier 79. , connected in parallel to the capacitor 85 via a resistor 87 (9NPN)
transistor, and a resistor 9 connected to the base of the transistor 89 and the output terminal of the Nandt gate 77 of the inhibition circuit F.
1.

The part surrounded by the dotted line H is a drive circuit for driving the magnet 101, which will be described later, and the drive port gH is connected to the output end of the latch circuit via a NAND gate (Nando game) 93.95 forming a latch circuit and a resistor 97. NPN with base
) has a transistor. 101 U A magnet (not shown) that is interlocked laterally after distance measurement in order to end the distance measurement operation.When the magnet 101 is de-energized, a locking claw (not shown) moves the photographing lens barrel (not shown). is configured so that it is stopped.

Point II! The part surrounded by J is binary glue Tupulukakunta 1
02, the counter 102 has an input C
K, a reset terminal R, and an output terminal Q.

The part surrounded by the dotted line is a drive circuit for driving the light emitting diode 103, and the drive circuit includes an NPN transistor having a base connected to the output terminal of the NAND gate 105 and the NAND gate 105 via a resistor 107. ) transistor 109, resistor 1111 operational amplifier 113, PNP connected to the light emitting diode 103) transistor 11
5. The collector of the transistor 115 and the amplifier 11
It has a variable resistor 117 and a resistor 119 connected between the non-inverting input terminals of No. 3.

The part surrounded by the point @L is a level detection circuit, and the detection circuit has a Nant gate 121 having an input terminal connected to the output terminal of the comparator 75.

The part surrounded by the dotted line M is a branch circuit connected to the output terminal of an oscillation circuit N, which will be described later, and is the output terminal Qt-j of the second DIL flip-flop circuit 125 constituting the branch circuit M.
It is connected to one input terminal of the AND gate 27, and its output terminal Q/Ii is connected to one input terminal of the AND gate 29. Further, the output terminal Q of the third D flip-flop circuit 127 constituting the frequency dividing circuit M is connected to the other input terminal of the AND gate 29, and the other output terminal Q is connected to the other input terminal of the AND gate 27. Connected to the input end.

Is the output end of the part surrounded by dotted line N a D type? This oscillation circuit includes an oscillator 133 connected to the clock input terminal CK of the rig flop circuit 123.

135 is a start switch whose one end is grounded and is opened at the start of the ranging operation; 137 is a switch interface circuit; 139 is the switch interface circuit 1;
The input end is connected to the start switch 135 via 37, and the output end Q of the D-type flip circuit 70 which is the output end of the frequency dividing circuit M is connected to the output end Q of the D-type flip circuit 131. A limit switch 145 that is grounded and is switched from an open state to a closed state when the light emitting diode 103 scans an object present at a predetermined distance, for example, 5 m, is connected to the limit switch 145 via the switch interface circuit 143. The input terminal connected to the switch 141 and the peak detection circuit #! 147a is an inverter connected to the output of the switch interface w11143, which has an input connected to the output of the IG.

Next, the operation of the camera distance measuring device according to the above configuration will be explained using FIG. 1, FIGS. 1A to 1C, and FIG. explain.

As shown in the second diagram, the start switch 135 is closed,
When the power switch (not shown) is turned on in the initial state where the limit switch 141 is closed, the voltage supply terminal VBA
A predetermined voltage is generated at the voltage supply terminal KVC, which is stable compared to the output voltage of T and the supply VBAT and generates an output voltage.

When the power switch is turned on and the start switch 135 is closed as described above, the potential at the output terminal of the switch interface circuit N1137 is at a low level (hereinafter referred to as LL).
Therefore, the potential at the output terminal of the AND gate 139 also becomes LL, and the potential at the output terminal of the NAND gate 105 becomes the NO level (hereinafter abbreviated as HL),
Further, transistor 109 becomes conductive. Therefore, the transistor 115 remains non-conductive, and the light emitting diode 103 that generates infrared rays remains off.

As mentioned above, when the light emitting diode 103 does not light up, there is no reflected light from the subject (not shown), so the light receiving circuit generates almost no signal, and as a result, the output terminal of the low-pass filter E The potential of is also the DC level when there is no signal. The potential of low-pass filter E at this time is
Since it is lower than the output potential of the voltage dividing circuit formed by the resistors 71 and 73, the potential at the output end of the comparator 75 becomes LL, and the potential at the output end of the Nandt gate 77 becomes HL. When the potential at the output end of the Nandt gate 77 becomes HL, the transistor 89
becomes conductive, the operation of the peak detection circuit q is prohibited, and the potential of the output of the operational amplifier 79 becomes HL. At this time, since the potential at the output end of the switch interface circuit 143 is HL as described above, the Nant gate 145
The output terminal potential of the amplifier 79 is H as described above.
When it becomes L, '\ immediately becomes LL, and the counter 102 is reset. Since the potential of the output terminal Q of the counter 102 becomes HL due to the above-mentioned reset, the potential of one input terminal 951 of the Nant gate 95 constituting the latch circuit also becomes HL.
becomes. On the other hand, at this time, the output terminal voltage limit switch 141 of the Nante gate 121 is in the open state, so that it becomes HL9, and the 30th input terminal 95 of the Nante gate 95
The potential of the Hirosaki distribution power supply c is set to IL (by the power-up clear signal PUC generated by turning on the switch), so the output state of the latch circuit is reliably held in response to the reset of the Hirosaki circuit 102, and the transistor 99
Fi remains conductive, and the excitation current continues to flow through the magnet 101 via the transistor 99. Therefore, the distance measuring mechanism of the camera is maintained in the initial state as shown in the first diagram.

When the start switch 135 is opened in such a state, the output terminal potential of the switch interface circuit 6137 becomes HL.
Therefore, the AND gate 139 is MA shown in the third diagram.
A drive signal as shown in FIG.
Since the open end becomes HL in response to the power-up clear signal PUC in synchronization with the output signal at the output end MA point of the Opens and closes in response to changes,
Further, the light emitting diode 103 repeats blinking at a timing synchronized with the opening and closing of the AND gate 139 as shown at 103A in FIG.

On the other hand, in synchronization with the opening of the start switch 135, the first
The scanning lever 203 shown in the figure begins to swing clockwise, the light emitting diode 103 blinks and scans the subject, and the lens barrel 213 is moved by the spring 215 to move the light emitting diode 10
There is a slight delay from the start of scanning No. 3, and the object moves backward from the closest position to the position corresponding to the infinite position. When the beam light from the light emitting diode 103 hits a subject (not shown) during the scanning, the beam light reflected by the subject passes through the first illustrated light receiving lens 201 to the light receiving element 225 of the light receiving circuit.
A signal with a waveform as shown in Fig. 4, in which low frequency components related to light such as sunlight and electric lights are suppressed, is input to the output terminal 3A of the light receiving circuit, and its level gradually rises. is dusted off. Among the signals appearing at the output terminals of the three light receiving circuits, the signals mainly having frequency components near the blinking frequency of the light emitting diode 103 are amplified by the amplification circuit B, and after death, are supplied to the respective input terminals of the analog switches 23 and 25. be done.

The waveform of the signal appearing at the output terminal 17 of the width increasing circuit B is shown as 17A in FIG.

On the other hand, the control signal input terminal of the analog μg switch 23 is connected to the branch circuit M via the AND gate 29 to 29A in FIG.
The synchronization signal shown in is given, and the analog switch is 250mb! Hiroand gate 2 at J signal input terminal
Since a synchronizing signal as shown in 27A in FIG. 3 is given from the branch circuit NIM via 7, the analog switch 23
The signals supplied to the respective inputs of 25 and 25 are sampled by the analog switches 23 and 25, and
It is also held by a subsequent hold circuit. Therefore, in response to the scanning of the light emitting diode 103, the output terminal 39A of the follower circuit 39 has a waveform (No. 6) shown at 39A in FIG.
In response to the scanning of the light emitting diode 103, @
A signal with a waveform as shown at 45A in FIG. 4 appears. There is a light emitting diode 1 at the output end of the synchronous detection circuit C for 39 people and 45 people.
In response to the scanning of 03, the output signal as described above appears, but when the level of the output signal is low and the transistor 59 is cut off, the output signal appearing at the output terminal 39AK is -55B/61R times (however, 55B is resistance 55
and 61R indicates the resistance value of the resistor 61), and the output signal output from the output terminal 45AK is multiplied by -55R763R (however, 63R indicates the resistance value of the resistor 63). ) and appears at the output terminal 53A of the compression circuit.

Then, the human input signal to the pseudo compression circuit is 39A in the $4 diagram.
Or, as shown in #i45, it gradually becomes larger, and the amplifier 5
The potential of the output terminal 53 of the transistor 590 is
When the level that makes the emitter conductive is exceeded, the output current of the amplifier 53 begins to flow not only through the resistor 55 but also through the resistor 57gJt and the emitter and collector, which are the main electrodes of the transistor 59. As shown, the output of the operational amplifier 53 is gradually compressed when the input signal level to the compression circuit exceeds a predetermined value. This degree of compression is determined by the sampling frequency component and the noise component L that is asynchronous with the sampling frequency among the signals generated by the resistor 55 and the resistor 5, which are removed by the low-pass filter E. A signal is supplied to the non-inverting input terminal of the amplifier 79, which is the input terminal of the peak detection circuit GO.

By the way, when the output signal level of the low-pass filter E is much lower than the divided voltage of the voltage dividing circuit connected to the input terminal of the comparator 750 (→), the potential of the output terminal 75A of the comparator 75 is 75A in FIG. As shown in , even if the potential at the input terminal 771 of the Nantes gate 77 is reversed to HL in synchronization with the opening of the start switch 135, the Nantes gate 77 remains in the LL state at this point. The output potential is HL
, and the transistor 89 remains conductive. Then, in response to the aforementioned scanning of the light emitting diode 103, when the output potential of the low-pass filter E exceeds the divided voltage of the voltage dividing circuits 71 and 73, the potential of the output end 75A of the comparator 75 has the waveform shown in FIG. As shown at 75A, the signal is suddenly reversed from LL to HL, and the transistor 89 is reversed to a non-conductive state, allowing the peak detection circuit U to perform the peak detection operation. When the peak detection operation becomes possible, the amplifier 7
The potential of the output 4i79 of the capacitor 85 rises in accordance with the rise in the potential at its input terminal, and the terminal voltage of the capacitor 85 rises in accordance with the rise in the potential at its output terminal 79A. The potential at the output terminal 79A of the amplifier 79 rises even after the transistor 89 is inverted to a non-conducting state, but when the potential at the output terminal 69A of the low-pass filter B starts to fall as shown at 69A in FIG. , the capacitor 85 stores the peak value of the input signal due to the action of the diode 810 since the transistor 89 is in a non-conducting state. For this reason, the operational amplifier 79
The feedback path is cut off, and the voltage difference between the potential at the non-inverting input terminal (G) and the potential at the inverting input terminal (→) is amplified at a very large amplification rate equal to the open loop gain of the amplifier 79. , the output of the amplifier 79 479 potential line drops at the instant KLLI.

In other words, the potential at the output end 79 of the amplifier 79 drops to LL as soon as the light emitting diode 103 scans the object at a predetermined position. By the way, at this point, the limit switch 141 is kept open and the potential of one input terminal of the Nandt gate 145 is HL, so the potential of the output terminal 79A of the peak detection circuit q becomes L L as described above. Then, the output potential of the Nant gate 145 is inverted from LL to HL, so the reset state of the counter 102 is released, and the counter 102 becomes an AND gate! 39 to the frequency divider circuit M
Start counting the pulses supplied from. When the output of the peak detection circuit G drops, the falling state continues for a predetermined period of time. Therefore, the counter 102 continues to count, and after a predetermined period of time has passed, the output of the counter 102 is reversed from 4QhHt to LL, the latch circuit is reset, and the output potential of the Nant gate 93 is H.
The signal is inverted from L to LL, and the transistor 99 is inverted to a non-conducting state. This rounded magnet 101 is de-energized,
The stopping claw 219 rotates to the right by the spring 221, and the locking claw 21
7.

As a result, the photographing lens barrel 213 is stopped at an appropriate position corresponding to the position of the subject.

On the other hand, as described above, when the output of the Nandts gate 93 is inverted from L to LL, the output of the Nandts gate 105 is held at HL, so the light emitting diode 103 is turned off and the ranging operation is completely stopped.

After the distance measuring operation is stopped, a known shutter control circuit (not shown) is activated, a synchro contact (not shown) is closed, and flash photography is performed.

In the operation of the distance measuring circuit during daylight photography, the light receiving element 1 is the light receiving element 2.
The operation is substantially the same as the operation during flash photography, so the explanation will be omitted.

In the above embodiment, the angle at which the light-receiving element looks at the subject increases during flash photography, and the output of the light-receiving element decreases, making it more susceptible to the influence of ambient light, but at this time, the level of ambient light is sufficiently low, so There is no need to increase the output of the light emitting element for projecting light.

As described above, according to the present invention, during flash photography, the angle at which the distance-measuring light-receiving element looks at the subject (i.e., the scanning area) is larger than that during daylight photography, and the distance-measuring area is expanded. When measuring distance in a dark place that requires flashlight emission, even if the aiming method of the object is slightly inaccurate, the possibility of defocusing is reduced, and distance measurement accuracy equivalent to daylight shooting can be obtained. It's something.

In the above embodiment, the angle at which the light-receiving element looks at the subject is switched by setting the flash device to the operating state, but it may also be switched by detecting the intensity of ambient light.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a non-input camera to which the present invention is applied and has a distance measuring device; Fig. 1A is a configuration diagram of a light receiving system of the camera shown in the first illustration; Fig. 1B is an external view of the camera shown in the first illustration; Figure 1C is a perspective view of members related to the flash device of the camera shown in the first illustration, Figure 2 is an electric circuit connection diagram of the camera shown in the first illustration, the third factor, and Figure 4 are output waveforms of various parts of the circuit shown in the second illustration. It is a diagram. In the figure, 1.225...light receiving element, 224...-7 mirror, 201... light receiving lens. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] What is claimed is: 1. A distance measuring device characterized in that the scanning area during low brightness is enlarged by a second compared to the scanning area during high brightness.