JPH0579837A - Light-projecting type distance measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a light-projecting type distance measuring apparatus which can measure distances with the simple constitution. CONSTITUTION:A photoelectric conversion photodetector 16 performs photoelectric conversion for the reflected light from an object and has a dead zone 16a at the center. The photodetector 16 is attached on a scanning plate 17. The change in photoelectric output appears by the scanning of the scanning plate 17. Therefore, control can be performed with a processing circuit. The scanning plate moves following the depression of a release lever 11. An electromagnet 23 is turned OFF with the processing circuit, and the phase of a control lever 21 is determined. The distance information corresponding to the distance to the object is set based on the phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device suitable for a small camera or the like.

[0002]

2. Description of the Related Art Conventionally, various optical projection type distance measuring devices utilizing the principle of triangulation have been proposed. Among them, the distance measuring device (Japanese Patent Application No. 55-1
24268) is a system for performing distance measurement by detecting a change in the photoelectric output of the light receiving element as a result of the light shielding plate scanning the surface of a single light receiving element. Hereinafter, it is referred to as a light-shielding plate scanning type distance measuring device.

[0003]

In the light-shielding plate scanning type distance measuring device, the light-receiving element and the light-shielding plate must be separately configured, which is a problem in that the configuration becomes complicated.

An object of the present invention is to provide a projection type distance measuring device capable of measuring distance with a simple structure.

[0005]

Embodiments Embodiments will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing the principle of a light-shielding plate scanning type projection type distance measuring device.

Reference numeral 1 denotes a light emitting element, 2 a light projecting lens, and 3 a light projecting axis. Reference numeral 4 is an optical axis reflected from the subject 8, 5 is a light receiving lens, and 6 is a light receiving element. Reference numeral 7 denotes a light shielding plate which scans the surface of the light receiving element. Reference numeral 9 denotes a camera body incorporating the above distance measuring device.

The operation will be described. The light emitted from the light emitting element 1 is condensed by the light projecting lens and becomes a light beam and hits the subject 8, and the reflected light is reflected by the light receiving lens 5 to a point on the light receiving element 6. Image as a spot. On the other hand, the light shielding plate 7 scans from the right to the left in the figure with a certain correlation with the distance to the subject. When the light blocking plate 7 crosses the optical axis 4, the reflected light from the subject is blocked and does not hit the light receiving element 6, and the photoelectric output of the light receiving element 6 is attenuated. When the light shielding plate 7 has passed the optical axis 4, the output again rises to the original level. This relationship is shown in FIG. 2, and the point lp at which the negative peak appears.
Is the distance to the subject. The position of the light spot formed on the light receiving element 6 in FIG. 1 shifts to the left as the subject becomes farther.

FIG. 3 shows an example of the mechanism of the distance measuring device incorporated in the camera together with the control circuit of the present invention.

In the figure, 11 is a release lever, which is biased upward by a spring 12. Reference numeral 17 denotes a scanning plate, which is a light blocking plate 17 for scanning the surface of the light receiving element 16.
There is a. The scanning plate 17 is biased to the right by a spring 18, but is locked by a locking member 13 and a spring 14. Reference numeral 19 is a gear and 20 is an pallet for controlling the traveling speed of the scanning plate. Reference numeral 21 is a control lever, which is given a rotation tendency in a clockwise direction by a spring, and engages with a pin 17c on the scanning plate 17 to rotate. Two
3 is an electromagnet, and 24 is an iron piece, and the spring 25 acts in the direction of separating from the electromagnet. Reference numeral 26 is a locking lever of the shutter front running lever 28, and 29 is a shutter front running lever 28.
Is a spring that biases the rightward direction. Reference numeral 30 denotes a stepped cam for determining the amount of extension of the objective lens, and a spring 32 imparts a rotation habit in a counterclockwise direction. Reference numeral 33 is a contact piece for selecting the resistor 36 according to the extension of the objective lens and using it as distance information for flashmatic or the like.

FIG. 4 shows an embodiment of a control circuit in the distance measuring device of the present invention.

In the figure, PD is a light receiving element, and a short-circuit current is converted into a voltage by an amplifier A1 in the first stage. R1 is a feedback resistor. C1 is an AC coupling capacitor, and A2 is a second stage amplifier for AC amplification. C
2 and R3 are feedback capacitors and resistors. D1
Is a detection diode, R6 and C3 are integrating resistors and capacitors, and R5 is a discharging resistor. A3 is a voltage follower, A4 is a DC amplifier with an integral output, R7 is an input resistance, and R8 is a feedback resistance. SH is a sample-hold circuit, A5 forms an operational amplifier, and the input resistance is R1.
0 and R11. CP1 is a comparator, an integrated output is input to the non-inverting input, a capacitor C6 and a resistor R17 are connected to the inverting input, and a diode D3 is connected between the inputs to form a clamp circuit. ing. The output of the comparator CP1 is connected to the transistor Tr1. R13 and C5 are a resistor and a capacitor for the second integrating circuit. A6 is an inverting amplifier, the output of which is connected to the non-inverting input of the comparator CP2. PSD
Is a positive inclination detection circuit, and this output and comparator CP
The output of 2 enters the OR circuit OR and is further connected to the flip-flop FF. Tr2 is a transistor for controlling the distance measuring electromagnet Mg. CP3 is a comparator, the first integrated output is input to the non-inverting input, and the inverting input is connected to a breaker including resistors R19 and R20. AND1 and AND2 are AND gate and INV
Is an inverter, and S2 is a switch which is turned on near the scanning completion point of the scanning plate. Tr3 is a warning LED control transistor, and Tr4 is an electronic buzzer-B control transistor. OSC is an oscillator. TME is a timer circuit, which is triggered by the shutter release switch S3 to control the operation of the IRED drive circuit DRV. IR
ED is an infrared emitting diode for light projection, which is pulse-driven by the transistor Tr5. S1 is a power switch.

Next, the operation of FIGS. 3 and 4 will be described. The operating waveforms of each part of the circuit are shown in FIG.

When the release lever 11 is pushed down, the power switch S1 is turned on to supply power to each part of the circuit, the light receiving circuit is activated, and the light projecting IRED is pulse-driven by a pulse of a constant cycle from the drive circuit DRV. It When the release lever 11 is further pushed down, the locking member 13 releases the locking of the scanning plate 17, and the governors 19 and 20 cause the scanning plate 17 to start scanning in the arrow direction in the figure at a constant speed. FIG. 5SCP shows the operation of the scanning plate 17, and n is the closest distance. When the light shielding plate 17a scans the light receiving element 16 and starts to shield the light spot on the light receiving element, the amplitude of the waveform of the output A of the AC amplifier A2 changes as shown in FIG.
When this AC signal is detected by diode D1 and integrated by R6 and C3, the waveform amplified by amplifier A4 becomes a dip waveform as shown in B. Further, the waveform passing through the sample hold circuit SH has a stepwise shape like D. When the waveforms B and D are input to the operational amplifier A5, the output E is obtained. Here, the clamp circuit is CP1, D3,
Although it is composed of C6 and R17, the inverted input waveform of CP1 is a circuit having a trailing delay with respect to the dip waveform of B as shown by C. And B> C
At this time, the transistor Tr1 is turned on, and the operational amplifier A
The output of 5 is clamped. This is to prevent a slight change in the integrated output B due to disturbance or the like when the light shielding plate 17a does not hit the light spot, thereby preventing malfunction. The output E is integrated by the resistor R13 and the capacitor C5 and amplified by the inverting amplifier A6 to obtain G. The output of the inverting amplifier A6 is connected to the non-inverting input of the comparator CP2, and the inverting input of the comparator CP2 is at the Gnd level. If the offset voltage of the non-inverting input and the inverting input is v, the non-inverting input is
The output is inverted when v exceeds the d level, and its waveform is indicated by H. The comparator CP2 is provided in the OR circuit OR.
And the output of the positive slope detection circuit PSD which will be described later are input. When the output of the comparator CP2 is inverted, the flip-flop FF of the next stage is set via the OR circuit OR, and the output Q-bar is inverted. The transistor Tr2 is turned off. Therefore, the distance measuring electromagnet Mg is cut off. That is, when the light shielding plate 17a scans on the light receiving element 16, the integrated output dips as shown by B, and the electromagnet Mg is turned off at the peak point. The position of the scanning plate 17 when the electromagnet Mg is turned off corresponds to the distance to the subject. The control lever 21 in FIG. 3 starts rotating clockwise following the movement of the scanning plate 17. The electromagnet Mg
When (23) is turned off, the hook of the iron piece 24 enters the ratchet portion of the control lever-21, and the rotation of the control lever-21 is stopped. Further, when the release lever 11 is pushed down, the shutter advance member 28, which is disengaged by the engaging lever 26, travels, and the step cam 30 is first rotated counterclockwise by a mechanism (not shown). The rotation angle of the step cam is controlled by the step cam stopper portion 21b of the control lever 21. Therefore, the extension amount of the objective lens is automatically set according to the distance to the object. After this, the opening / closing operation of the shutter is performed. The contact piece 33 also rotates with the extension of the objective lens, and a resistance value is selected according to the subject distance, and is used as information for flashmatic or interlocking outside warning. The switch S2 is a switch that is turned on when the scanning plate has finished scanning from a short distance to a long distance, and is used as a timing signal for an out-of-interlocking warning described later or as an off signal of the infrared light emitting diode IRED. The switch S3 is turned on by the operation of the shutter advance member 28, and is used as a trigger signal for the timer-circuit TME. The purpose of the timer-circuit TME is the release lever-1.
Even if you press 1 quickly, IRED is used until the distance measurement operation ends.
Switch S2 is set to I in this case.
It is not necessary to turn off RED. Also,
It is also possible to turn off the IRED by turning off the electromagnet Mg.

Next, FIG. 6 and the warning circuit will be described. In FIG. 6, the members having the same numbers as those in FIG. 3 are members having the same function.

In this embodiment, the light receiving element 16 has a dead zone 16a at its center and is mounted on the scanning plate 17. As the scanning plate 17 scans, a photoelectric output change appears in exactly the same manner as in the embodiment shown in FIG. 3 and can be controlled by the circuit shown in FIG. In addition, the lever-3 that always works to return the release lever-11
3 is arranged together with the spring 34, and when the finger is released from the release lever 11, the release lever 11 and the scanning plate 17 are always in the original state. In this mechanism, the scanning plate 17 is a relay.
Although the vehicle travels following the depression of the shifter 11, the electromagnet 23 is turned off at the apex of the dip of the integrated waveform as in the above-described embodiment, and the phase of the control lever 21 is determined. Further, the integrated output of FIG. 1 is input to the non-inverting input of the comparator CP3 of FIG. 4, and the bridger R19,
The partial pressure of R20 is input. Also, And Gate A
The comparator output, the flip-flop FF output, and the inverted signal of the switch S2 are input to ND1. That is, when the scanning plate 17 has finished traveling, the switch S2
If the OFF signal of the electromagnet 23 is not yet obtained at the time when is turned on and the first integrated output is sufficiently high, this AND gate AND1 is opened and the next AND circuit AND
2, the oscillator OSC output together with the drive circuits Tr3, Tr4
Operate. The blinking of the LED or the intermittent sound of the electronic buzzer B warns that the distance measuring device does not work normally or that the distance is extremely close. Therefore, the photographer can remove the finger from the release lever 11 and restart the distance measurement. Here, the iron piece lever 24 of the electromagnet 23 will be reset by a known method not shown.

Next, the positive inclination detection circuit will be described with reference to FIG.

As shown in FIG. 7A, the light receiving element 16,
It is assumed that the light shielding plate 17a and the light spot 35 are slightly displaced from the ideal state. This is a problem that may occur due to mounting errors during production. As shown in B of FIG.
When the scanning plate 17 (SCP) runs, the integrated output does not dip and becomes a monotonically increasing signal. Even in this case, the electromagnet Mg
As an example of a circuit for turning off, a circuit as shown in FIG. For the non-inverting input of the comparator CP4,
The capacitor C7, the charging resistor S25, and the switching transistor Tr6 are configured to operate by the output of the comparator CP4, and the first integrated output is input to the inverting input of the comparator CP4. This circuit sends an operation signal to the next stage OR gate when the first integrated output starts increasing, and the electromagnet 23
Is something that can be turned off. OR circuit OR
Since the dip peak detection signal is also input to,
In general, the flip-flop FF operates by opening the OR gate OR at the earlier timing of the output of the comparator CP2 and the output of the positive slope detection circuit PSD in FIG.

FIG. 8 shows another embodiment of the distance measuring electromagnet Mg control circuit.

As shown in FIG. 3C, the scanning plate SC. P
If the intensity of the reflected light from the subject fluctuates as shown by B before scanning, the electromagnet Mg will be turned off at point a by the conventional method, resulting in a malfunction.
Correct re-excitation is possible by immediately re-exciting like the Mg waveform of (c) and turning off again at the peak of the normal dip signal, that is, at point b. In FIG.
The iron piece 24A of the electromagnet 23 uses a slide type, and the lock lever is locked by the locking portion 17d until the scanning plate 17 starts traveling.
The operation of 24B is blocked. Therefore, after the scanning plate 17 starts traveling, the ratchet of the control lever-21 can be stopped by the lock lever-24B. The circuit is formed by inserting a one-shot multivibrator OST in the next stage of the OR circuit OR as shown in FIG. The period during which the electromagnet 23 is off is determined by the values of the capacitor C8 and the resistor R27.

Regarding the distance display, the control lever-2
It can be easily implemented by providing a display member corresponding to the rotation angle of 1. In principle, the stopper of the step cam
It suffices to make the portion 21b visible from the finder.

Further, when the traveling of the scanning plate 17 is stopped by turning off the electromagnet 23, the display member serves as the scanning plate 1.
It is also possible to provide a member interlocking with 7.

[0023]

According to the present invention, since the light receiving element provided with a dead zone in part is adopted, the structure of the distance measuring device is simplified.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of a light-shielding plate scanning type light-projecting distance measuring device.

FIG. 2 is a photoelectric output waveform diagram in the distance measuring device.

FIG. 3 is an example of a mechanism forming a distance measuring device.

FIG. 4 is an example of a control circuit of a distance measuring device.

5 is a diagram showing an output waveform of each unit for explaining the operation of the control circuit of FIG.

FIG. 6 is an example of another mechanism of the distance measuring device.

FIG. 7 is an example of a positive inclination detection circuit and its operation explanatory diagram.

FIG. 8 is an example of another mechanism of a distance measuring device, an example of a drive circuit of a distance measuring electromagnet, and an operation explanatory diagram thereof.

[Explanation of symbols]

 A1, A2-A6 ... Amplifier CP1-CP3 ... Voltage comparator SH ... Sample-hold circuit PSD ... Positive slope detection circuit OSC ... Oscillator PD ... Photodetector IRED ... Infrared light emitting diode TME ...... Timer circuit DRV ...... IRED drive circuit B ...... Buzzer 1 ...... Light emitting element 6 ...... Light receiving element 7 ...... Light shielding plate 17 ...... Scanning plate 21 ...... Control lever 23 ...... Electromagnet 30 ...... Step cam S1 …… Power switch 33 …… Contact piece 35 …… Light spot

Claims (1)

[Claims] 1. A light projecting means for projecting light emitted from a light emitting element onto an object, a drive circuit for causing the light emitting element to emit light in a pulse shape, and a moving circuit which moves in correlation with a distance to the object. A photoelectric conversion signal that photoelectrically converts the reflected light of the light emitting element to be reflected is generated, and a light receiving element in which a dead zone is provided in a part thereof, an integration circuit that generates an integration signal that integrates the photoelectric conversion signal, and the integration signal A delay circuit that generates a delayed signal that is delayed, a difference circuit that generates a difference value between the integrated signal and the delayed signal, and a peak of the integrated signal that occurs when the dead zone intersects with the reflected light as the difference value. A peak detection circuit for detecting the change based on the position in the moving process of the light receiving element when the change in the photoelectric conversion signal is detected by the peak detection circuit, and a distance corresponding to the distance to the object. Light projecting distance measuring apparatus comprising a distance information setting means for setting information.