JPH056645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a distance measuring device used in a camera, etc., which projects light emitted from a light emitting element toward a distance measuring object, and reflects the reflected light between a common electrode and a pair of detectors. The present invention relates to an improvement in a triangular distance measuring device that receives light with a semiconductor optical position detecting element having an electrode.

Conventionally, as a distance measuring device using the method described above,
This method has been proposed in Japanese Patent Application Laid-Open No. 177107/1983.

In general, when measuring distance by receiving light reflected from a distance measurement target by a light emitting element using a light receiving element,
The intensity of the reflected light varies by a factor of 1,000 or more depending on the reflectance of the object to be measured, the distance, etc. Therefore, the amplifier circuit that amplifies the output of the light receiving element needs to have a dynamic range of 60 dB or more.

Possible ways to widen the dynamic range include logarithmic compression of the light receiving element output and automatic gain adjustment of the amplifier circuit, but in the former case, when the amount of light received is large and the output difference between the light receiving elements is small, the S/N In the latter case, a feedback system is required, which increases unstable factors such as oscillation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to gradually increase the output of a light-receiving element from an apparently zero or minute value by a simple means without having the drawbacks of the conventional example, and to set the comparison circuit to a certain setting that is easy to distinguish. The object of the present invention is to provide a distance measuring device that determines the distance measuring state when a value is reached.

Embodiments of the present invention will be described below based on the drawings.

First, in Fig. 1, 1 is a clock pulse generation circuit (oscillation frequency f ₀ =16KHz, hereinafter referred to as OSC).
2 is a time forming circuit (time t=
25ms), 3 is and game, 4 is transistor,
5 is an inverter, 6 is a transistor, 7 is a constant current circuit, 8 is a capacitor, 9 is a buffer circuit, 1
0, 11, and 12 are transistors forming a constant current circuit; 13 is an infrared light emitting diode (hereinafter referred to as
(written as IRD).

Reference numeral 14 denotes a semiconductor optical position detection element, which has a semiconductor substrate 15 having a relatively large surface, and a semiconductor layer 16 of a conductivity type different from that of the substrate 15 is formed on one surface of the semiconductor substrate 15. A resistive layer 17 is formed on the semiconductor layer 16, and a pair of electrodes (for detection) are provided at both ends of the resistive layer 17.
17a and 17b are provided, and a semiconductor substrate 15
A common electrode 18 is provided.

19 and 20 are AC amplifier circuits, 21 and 2, respectively.
2 is a band filter circuit (center frequency f ₀ =
(hereinafter referred to as BPF), 23 and 24 are detection circuits, 25 and 26 are smoothing circuits, 27 and 28 are DC amplifier circuits, respectively.
0 and 31 are respectively comparator circuits (hereinafter CMP
), 32 is a constant current circuit, 33, 34 and 35 are reference voltages Vr ₁ , Vr ₂ and Vr ₃ to the inverting input terminal (-) of CMP 29 and the non-inverting input terminal (+) of CMP 30, 31, respectively. Partial voltage resistance to give, 36
are AND gates, 37 and 38 are D-type flip-flop circuits, and 39 is an R- and S-type flip-flop circuit (the flip-flop circuits are hereinafter commonly referred to as FF);
They are connected as shown in the figure.

Next, the operation shown in FIG. 1 will be explained with reference to FIG. 2.

When a power switch (not shown) is closed at the start of the operation, power is supplied to each part of the circuit, and the FFs 37, 38, and 39 are released from reset.

Then, the OSC1 operates to generate a clock pulse with a period of 62.5 .mu.s, and the output of the time forming circuit 2 is inverted to the "H" level for a time of t=25 ms.

Therefore, the clock pulse passes through the AND gate 3 for that period of time, and the transistor 4 repeats conduction and interruption in response.

On the other hand, while the output of the time forming circuit 2 is inverted to the "H" level for a time of 25 ms, the output of the inverter 5 is inverted to the "L" level and the transistor 6 is cut off. When the constant current is I and the capacitance of the capacitor 8 is C, the voltage V at the output terminal a of the buffer circuit 9 is given by the relational expression V=(1/C)I, t. It rises as shown in A. As a result, the collector-emitter current (i ₁ ) flowing through the transistor 10 gradually increases, and the collector-emitter current (i ₂ ) of the transistor 12 also increases in proportion to the current (i ₁ ). become.

Therefore, in response to the conduction and cutoff of the transistor 4, the current (i ₂ ) of the transistor 12 increases intermittently as shown by the circles, and the IRD 13 is pulsed and the amount of light emitted increases. increases monotonically from low light intensity to high light intensity.

The light projected by the lighting of the IRD 13 is reflected from the distance measurement target and is received by the semiconductor optical position detection element 14.

Here, when the reflected light spot X hits between the electrodes (for detection) 17a and 17b, a current I ₁ flows from the point of incidence to the electrode 17a through the resistance layer 17, a current I ₂ flows to the electrode 17b, and also to the common electrode. A current I ₃ flows to each of them, and the following relationship holds between them.

I ₃ = I ₁ + I ₂ Then, if the resistance of the resistance layer 17 is made uniform, the distance between the incident point of the reflected light spot X and the electrode 17a is l ₁ , and the distance between the incident point and the electrode 17b is l ₂
Then, the relationship l ₁ · I ₁ = l ₂ · I ₂ holds true.

Based on this condition, the received light output at points c and c′ is
As shown in ○C, it is generated by being superimposed on the DC component due to natural light.

Also, d and after the AC amplifier circuits 19 and 20
The output at point d' appears amplified as shown in ○D.

Furthermore, the outputs at points e and e' after BPF21 and 22 have their center frequency f ₀ and the oscillation frequency f ₀ of OSC1 set to the same value, so the waveform of ○D is as shown in ○E. It appears to be amplified.

Furthermore, f and after the detection circuits 23 and 24
The output waveform at point f' is as shown in ○F, and the DC amplifier circuits 27 and 28 pass through the smoothing circuits 25 and 26.
The output voltages Vg and Vg' at the subsequent points g and g' gradually rise from the predetermined values, as shown in ◯.

As shown in FIG. 2, when the object to be measured is located at a short distance, the reflected light spot Since the shift l ₁ ≪ l ₂ occurs, the output voltage Vg at point g becomes the output voltage at point g′
When the output voltage Vg reaches the reference voltage Vr ₁ and is sufficiently higher than Vg', the output of the CMP29 is inverted to the "H" level and remains "H" for the previous time t.
AND gate 36 to which the level signal was given
opens and its output is inverted to "H" level. On the other hand, at that point, the output voltage Vg' at point g' has not even reached the reference voltage Vr ₃ , so CMP30 and CMP31
Both outputs remain at the "H" level. Therefore, the FFs 37 and 38 whose clock is the rising signal of the output of the AND gate 36 to "H" level are as follows.
Both read "H" level signals, store "H" level signals in the husband's output terminals Q ₁ and Q ₂ ,
Also, FF3 uses the rising signal as a set pulse.
9, the output terminal _Q3 is inverted to the "H" level.

Furthermore, when the object to be measured is located at a medium distance position, the reflected light spot X is biased to the left with respect to the semiconductor optical position detection element _{14 ,} as shown in _FIG. < l ₂ , and in a similar operation, the output voltage Vg' is between Vr ₂ < Vr ₃ , so the output terminal Q ₁ of FF37 receives a "H" level signal, and the output terminal Q 1 of FF37
The output terminals Q ₂ of the FF 39 each store a signal at the "L" level, and the output terminal Q ₃ of the FF 39 is inverted to the "H" level.

Furthermore _, if _the distance measurement target exists at a boundary position to a long distance, the reflected light spot Since l ₁ ≒ l ₂ at that time, the output voltages Vg and Vg' are almost equal,
At the time of this determination, the output voltage Vg′ is equal to the reference voltage Vr ₂
Therefore, the output terminals Q ₁ and Q ₂ of the FFs 37 and 38 store "L" level signals, and the output terminal Q ₃ of the FF 39 is inverted to "H" level.

Furthermore, if the object to be measured is located at a very far distance, as shown by the chain lines at c ₁ and c ₂ ,
The reflected light spot X' is detected by the semiconductor optical position detection element 1.
4, it is biased to the right side and is in a state where l ₁ > l ₂ ,
Due to the extremely long distance, the output voltage Vg does not reach the reference voltage Vr ₁ within the previous time t (this may also happen if the distance measurement target has a low reflectance), and the CMP
The output of FF 39 remains at the "L" level, and when the time t ends, the AND gate 36 closes the gate, so FF 39 is not set and the output terminal Q ₃
is maintained at the "L" level.

Note that at this time, the output of the AND gate 36 does not invert to the "H" level, so the FF37
and 38 do not perform a read operation.

That is, as shown in the truth value chart in Figure 3, FF
It is set to distinguish near, medium and long distance based on the signal level status of output terminals Q ₁ and Q ₂ of FF 37 and 38, and further, when output terminal Q ₃ of FF 39 is at "L" level. is FF37 and 38
This is set to give priority to long-distance discrimination.

Further, the reference voltage to the CMPs 30 and 31 in FIG. 1 is a fixed bias, and the output voltage Vg' and the output voltage Vg are compared in absolute value.

In the embodiment of FIG. 4, the reference voltage to the CMPs 30 and 31 is given by dividing the fluctuating output voltage Vg, and therefore the output voltage Vg' is the output voltage
Comparisons are made as a percentage quantity to Vg. Note that Vb of the voltage dividing circuit is biased to, for example, the normal voltage level of the light receiving element output circuit of the semiconductor optical position detection element 14 when the IRD 13 is not operating.

In addition, in the circuit operation shown in FIG. 1, when the output of the CMP 29 is inverted to the "H" level, the state of the output voltage Vg' is determined, but the AND gate 36
Due to the following accumulated operation delay time, the determination may lack accuracy.

On the other hand, the feature of the embodiment shown in FIG. 4 is that, as mentioned above, the output voltage Vg' is
Since the determination is made based on the ratio to Vg, the accuracy can be improved compared to the previous embodiment.

Note that the number of stages of the distance measurement output mentioned above can be increased or decreased, and when determining a long distance using FF39,
It is also possible to issue a warning at the same time.

In the above embodiment, the distance measurement output is set to the reference voltage Vr ₂ ,
Although it is obtained digitally according to the level and number of stages of Vr ₃ , an example will be described below in which the distance measurement output is obtained by further dividing it into smaller parts.

First, the first one will be explained with reference to FIGS. 5 and 6. Note that the same elements as in the previous embodiment are given the same reference numerals.

In FIG. 5, 41 is a comparator circuit;
2 and 43 are constant current circuits and resistors that apply a reference voltage Vr to the inverting input terminal (-) of the comparator circuit 41, 44 is an AND gate, 45 is an analog switch, 46 is an inverter, 47 is a capacitor, 4
8 is a current amplification circuit, 49 is a comparator circuit (the comparator circuit is hereinafter commonly referred to as CMP), and 50 and 51 are connected to the non-inverting input terminal (+) of CMP 49 on one side in the movable range of the photographing lens. A constant current circuit and a potentiometer that provide a displacement voltage corresponding to movement from one extreme position to the other extreme position, 52 an R, S type flip-flop circuit (hereinafter referred to as FF), 53 an AND gate, and 54 a transistor. , 55 is an electromagnet for stopping the movement of the operating member (lens settling) of the photographic lens.

Next, in FIG. 6, 56 is a lens setting ring, which is arranged rotatably around the optical axis.
In addition, the spring 57 imparts dextrorotation, and the right rotation displaces the photographing lens from an infinity position to a close distance position, and also forms a stepped portion 56a and a ratchet tooth 56b. .
Reference numeral 58 denotes a lens-driving release electromagnet, which is composed of an iron core 58a, a coil 58b, and a permanent magnet 58c. Reference numeral 59 denotes an iron piece lever for the release which is pivotally connected to the shaft 60 and given left-handed rotation by the spring 61, and includes a hook 59a that can engage with the stepped portion 56a of the lens setting ring 56 and an iron core of the electromagnet 58. An iron piece 59b opposite to 58a is formed. 62 is a pin that limits the left rotation amount of the iron piece lever 59. Reference numeral 63 designates a locking iron piece lever pivotally mounted on a shaft 64 and given dextrorotation by a spring 65, which includes a hook 63a that can engage with the ratchet teeth 56b of the lens setting ring 56, and is the same as that shown in FIG. An iron piece 63b facing the electromagnet 55 is formed.

Note that the potentiometer 51 in FIG.
As shown in FIG. 6, the lens setting ring 56
The brush 51a is supported by a resistor 51c and a conductor 51d formed on a substrate 51b.

Therefore, the operations in Figures 5 and 6 are shown in Figure 2 ([]
This will be explained together with the voltage (refer to the voltage inside).

Similarly to the above, in the states a1 and a2 of Fig. 2,
The output voltage Vg at point g is sufficiently higher than the output voltage Vg' at point g', and the potentials at points g and g' rise while maintaining this relationship.

Also, at this stage, the AND gate 44 is closed and the output of the inverter 46 is at the "H" level, so the analog switch 45 is open and the capacitor 47 is charged by the output voltage Vg' at point g'. Go.

Then, when the output voltage Vg at point g reaches the reference voltage Vr, the output of the CMP 41 is inverted to the "H" level, and as a result, the AND gate to which the "H" level signal was applied for the previous time t 44 is opened and its output is inverted to the "H" level, and the FF 52 is set to invert and hold the output Q to the "H" level, and the output of the inverter 46 is inverted to the "L" level and the analog switch 45 is inverted. close it. Therefore, the output voltage at point g' when the output voltage Vg at point g reaches the reference voltage Vr is stored in the capacitor 47.
Vg′ (V ₁ ) is stored. Further, the voltage V ₁ is amplified by the current amplification circuit 48 and applied to the inverting input terminal (-) of the CMP 49 .

In addition, since the potentiometer 51 which applies an input voltage to the non-inverting input terminal (+) of the CMP 49 is located on the high potential side in the initial state, the initial output state is set at the "H" level.

Therefore, since the AND gate 53 opens the gate and makes the transistor 54 conductive, the electromagnet 55 is energized and holds the iron piece lever 63 by attraction.

Then, after the end of the previous time t, the coil 58b of the electromagnet 58 is turned on by a circuit operation (not shown).
When pulsed in a direction that cancels the magnetic force of the permanent magnet 58c, the iron piece lever 59 is rotated to the left by the tension of the spring 61, and the hook 59a is removed from the stepped portion 56a of the lens setting ring 56. As a result, the ring 56 begins to rotate to the right due to the tension of the spring 57.
The photographing lens is displaced from the infinity position to the close distance position, and the brush 51a is slid on the resistor 51c and the conductor 51d, thereby displacing the potentiometer 51 from the high potential side to the low potential side. move it.

Then, when the potential at the non-inverting input terminal (+) of the CMP 49 drops to the potential at the inverting input terminal (-), the output of the CMP 49 is inverted to the "L" level and the AND gate 53 is closed. the result,
Since the transistor 54 is cut off and the electromagnet 55 is demagnetized, the iron lever 63 rotates clockwise due to the tension of the spring 65, and the hook 63a engages with one of the ratchet teeth 56b, stopping the lens setting ring 56 from rotating clockwise. The photographing lens is fixed in a predetermined position.

In addition, if the object to be measured is located a little further away, for example as shown in Fig. 2 b1 and b2, the voltage corresponding to the above-mentioned memory voltage _V1 is
Changes to V ₂ .

Furthermore, if the object to be measured is located further away, for example, as shown by the solid lines in FIG. 2 C1 and C2 (the reflected light spot case), what corresponds to the above-mentioned storage voltage V ₁ changes to voltage V ₃ .

Furthermore, if the object to be measured is located at a very far position, the reflected light spot X' will be biased to the right with respect to the semiconductor optical position detection element 6, as shown by the chain lines in FIGS. 2C1 and C2. , due to the extremely long distance, the output voltage Vg is equal to the reference voltage Vr within the previous time t.
(This may also happen when the distance measurement target has a low reflectance), the output of the CMP 41 remains at the "L" level, and when the time t ends, the output of the time forming circuit 2 Once returned to the "L" level, the output of the AND gate 44 cannot be inverted to the "H" level. Therefore, FF52 is
It is not set and the output Q is held at the "L" level, keeping the AND gate 53 closed.

As a result, since the electromagnet 55 is not excited from the initial state and does not attract the iron piece lever 63, the lens setting ring 5
6 rotates to the right and the first tooth of the ratchet tooth 56b opposes the hook 63a, the iron piece lever 63 immediately rotates to the right and the hook 63a moves to the right.
, the right rotation of the lens setting ring 56 is stopped, and the photographing lens is fixed at the infinity position.

Next, another embodiment will be described with reference to FIGS. 7 and 8. Note that the same elements as in the previous embodiment are given the same reference numerals.

66, 67 are CMP, 68, 69 and 70 are constant current circuits, resistors and potentiometers, 71, 7
2 and 73 are NAND gates (note that the above elements constitute a window comparator circuit in which the output voltage of the current amplifier circuit 48 is input and the states of NAND gates 72 and 73 are output).
4 is an AND gate, 75 is an OR gate, 76 is an inverter, 77 to 80 are transistors, and 81 is a motor.

Reference numeral 82 denotes a lens setting ring, which is arranged to be rotatable about the optical axis and forms a partial gear 82a. A pinion 83 is fixed to the rotating shaft of the motor 81, which is the same as that shown in FIG. 84 is an intermediate gear that meshes with the pinion 83 and the partial gear 82a of the lens setting ring 82.

Note that the potentiometer 70 in FIG.
As shown in FIG. 8, the lens setting ring 82
The brush 70a is supported by a resistor 70c and a conductor 70d formed on a substrate 70b.

As mentioned above, the output voltage of the current amplification circuit 48 is
Apart from extremely far distances, the range is set to increase as the distance to the target is near, medium, and far.

Since it is a window comparator circuit, the output voltage Vx of the current amplifier circuit 48 is CMP
If the voltage is higher than the voltage Vy of the non-inverting input terminal (+) of CMP66, the output of CMP66 is "L" level,
Since the output of CMP67 is at "H" level, the output of NAND gate 71 is at "H" level,
The output of NAND gate 72 is at "H" level, and the output of NAND gate 58 is at "L" level.

On the other hand, if the output voltage Vx is lower than the voltage Vz of the inverting input terminal (-) of the CMP67, the CMP67
Since the output of the CMP 67 is at the "H" level and the output of the CMP 67 is at the "L" level, the subsequent output states will have a reverse relationship to that described above.

In any of the above cases, since there is a difference between the two inputs of the motor drive circuit, the motor 81 rotates in corresponding directions to drive the lens setting ring 82.

Furthermore, when the output voltage Vx is placed in the relationship Vy>Vx>Vz, the outputs of the CMPs 66 and 67 both become "H" level and the output of the NAND gate 71 becomes "L" level, so the NAND gate 72
and 73 are both at the "H" level, and since both inputs of the motor drive circuit are at the same potential at this time, the motor 81 does not rotate.

That is, by operating the potentiometer 70 in conjunction with the movement of the lens setting ring 82 driven by the rotation of the motor 81, the voltages Vy and Vz are changed with respect to the output voltage Vx at that time, and Vy
The relative position of >Vx>Vz is detected and the photographing lens is fixed at a predetermined position.

Furthermore, as mentioned above, FF52 is not set,
When the output Q remains at the "L" level, the output of the AND gate 74 is at the "L" level, and the OR gate 75
The output of Vx is held at “H” level, and the output voltage Vx
The photographing lens is driven to a very far distance position.

In addition, at this time, the operation to detect the state of Vy>Vx>Vz becomes irrelevant, and the current that drives the photographic lens toward the far distance side continues to flow through the motor 81, so a limiter is provided. It is preferable to leave it there.

Next, another embodiment will be described with reference to FIG. Note that the same elements as those in the above embodiment are given the same reference numerals.

86 is a 4-bit A/D converter circuit, 87 to 90 are AND gates, and 91 is a 4-bit A/D converter circuit, for example.
BIT magnitude comparator circuit, 92
93 is a motor that drives lens setting by its rotation; 94 is a motor 9;
This is, for example, a 4-bit encoder that digitizes the rotation amount of 3.

The analog amount of the output voltage of the current amplification circuit 48 is
The A/D converter circuit 86 outputs signals from "L", "L", "L", "L" to "H", "H" through four output terminals.
”、
It is encoded as one of 16 levels of digital quantities from "H" to "H", and the 16 levels are, for example, divided into 16 from the extremely far distance position to the close distance position.

Therefore, the output of the A/D converter circuit 86 is
It is input to the magnitude comparator circuit 91 through AND gates 87-90. The lens setting is driven by rotating the motor 93 by the motor drive circuit 92. As a result, the photographing lens is displaced from the infinity position to the close distance position. When the output of an encoder 94 that converts the amount of rotation of the motor 93 into a digital amount matches the input of the comparator circuit 91, the motor 93 is stopped and the photographing lens is fixed at a predetermined position.

Also, as mentioned above, FF52 is not set,
When the output Q remains at the "L" level, the outputs of the AND gates 87 to 90 are both held at the "L" level, which is the same as the extreme distance state described above, so the photographing lens is at the infinity position. It is fixed at

In each of the embodiments, if the FF 52 is not set and a long-distance state is set, an alarm may also be issued.

As described above, the present invention achieves stable operation using a simple configuration that monotonically increases the amount of light emitted by the light emitting element from a small amount of light to a large amount of light without performing logarithmic compression of the output of the light receiving element or automatic gain adjustment of the amplifier circuit. It is possible to determine the distance measurement state.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the relationship between the state of the reflected light spot and the output voltage with respect to the light receiving element, and Fig. 3 shows an example of the distance measurement output. Diagrams of truth values, Figures 4 and 5
7 and 9 are partial circuit diagrams showing other embodiments of the present invention, and FIGS. 6 and 8 are partial circuit diagrams of the photographing lens drive mechanism corresponding to FIGS. 5 and 7, respectively. It is an explanatory diagram showing an example. DESCRIPTION OF SYMBOLS 1... Clock pulse generation circuit, 2... Time forming circuit, 9... Buffer circuit, 13... Infrared light emitting diode, 14... Semiconductor optical position detection element,
17a, 17b...electrode (for detection), 18...common electrode, 19 and 20...AC amplifier circuit, 21 and 22...bandwidth filter circuit, 23 and 24...
...detection circuit, 25 and 26 ... smoothing circuit, 27 and 28 ... DC amplifier circuit, 48 ... current amplifier circuit, 51 and 70 ... potentiometer, 55 ...
...Electromagnet, 56 and 82...Lens setting, 81 and 93...Motor, 86...A/D converter circuit, 91...Magnitude comparator circuit, 92...Motor drive circuit, 94...Encoder, and X′...Reflected light spot.

Claims (1)

[Claims] 1. A triangular distance measurement method in which light emitted from a light emitting element is projected toward a distance measurement target, and the reflected light is received by a semiconductor optical position detection element having a common electrode and a pair of detection electrodes. In the distance measuring device, the amount of light emitted from the light emitting element is monotonically increased from a small amount of light to a large amount of light within a certain period of time, and a set value is set at which there is an output between a common electrode and one detection electrode in the semiconductor optical position detection element. A distance measuring device characterized in that the state of the output between the common electrode and the other detection electrode is determined when the detection electrode reaches the point in time. 2. In a triangulation distance measuring device in which light emitted from a light emitting element is projected towards a distance measuring target and the reflected light is received by a semiconductor optical position detection element having a common electrode and a pair of detection electrodes, When the amount of light emitted by the light emitting element is monotonically increased from a small amount of light to a large amount of light within a certain period of time, and the output between the common electrode and one detection electrode in the semiconductor optical position detection element reaches a certain set value, A distance measuring device characterized in that the output between the common electrode and the other detection electrode is compared with a predetermined ratio of the output between the common electrode and the one detection electrode. 3. The distance measuring device according to claim 1 or 2, characterized in that the output between the common electrode and the other detection electrode is compared with a plurality of levels. 4. Claim 1, characterized in that when the output between the common electrode and one of the detection electrodes does not reach a certain set value within a certain period of time, the distance measurement output is determined as long distance. Or the distance measuring device according to item 2. 5. In a triangulation distance measuring device in which light emitted from a light emitting element is projected toward a distance measurement target and the reflected light is received by a semiconductor optical position detection element having a common electrode and a pair of detection electrodes, The amount of light emitted by the light emitting element is monotonically increased from a small amount of light to a large amount of light within a certain period of time, and when the output between the common electrode and one detection electrode in the semiconductor optical position detection element reaches a certain set value, The state of the output between the common electrode and the other detection electrode is stored as a voltage value and applied to one input terminal of the comparator circuit, and then the photographing lens is directed from one extreme position to the other extreme position in the movable range. and sweep the potential of the other input terminal of the comparator circuit from one extreme value to the other extreme value in conjunction with the driving operation, and when the potentials of both input terminals match, A distance measuring device characterized in that driving of the photographing lens is stopped. 6. In a triangulation distance measuring device in which light emitted from a light emitting element is projected towards a distance measuring target and the reflected light is received by a semiconductor optical position detection element having a common electrode and a pair of detection electrodes, The amount of light emitted by the light emitting element is monotonically increased from a small amount of light to a large amount of light within a certain period of time, and when the output between the common electrode and one detection electrode in the semiconductor optical position detection element reaches a certain set value, The state of the output between the common electrode and the other detection electrode is stored as a voltage value and applied to one input terminal of the window comparator circuit, and the potential corresponding to the position within the movable range of the photographic lens is applied to the window comparator circuit. is applied to the other input terminal of the comparator circuit, and the photographing lens is driven by a servo motor connected between the output terminals of the comparator circuit and rotated in accordance with the direction of unbalance of the input voltage, and the potential of both input voltages is 1. A distance measuring device, characterized in that when the distance matches within a predetermined threshold having a width, rotation of the servo motor is stopped and driving of the photographing lens is stopped. 7. In a triangulation distance measuring device in which light emitted from a light emitting element is projected towards a distance measuring target and the reflected light is received by a semiconductor optical position detection element having a common electrode and a pair of detection electrodes, The amount of light emitted by the light emitting element is monotonically increased from a small amount of light to a large amount of light within a certain period of time, and when the output between the common electrode and one detection electrode in the semiconductor optical position detection element reaches a certain set value, Converting the voltage value of the output state between the common electrode and the other detection electrode into a digital value and storing it, and then driving the photographing lens from one extreme position of the movable range to the other extreme position, A distance measuring device characterized in that the driving step amount is converted into a digital amount by an encoder, and when the digital amount matches the stored digital value, the driving of the photographing lens is stopped. 8 If the amplified output between the common electrode and one detection electrode does not reach a certain set value within a certain period of time,
8. The distance measuring device according to claim 5, 6, or 7, characterized in that the photographing lens is stopped at an extreme position on the long distance side with priority.