JPH0552557A - Distance measurement device - Google Patents

Abstract

PURPOSE:To obtain the device enabling highly precise distance measurement even for a subject at a great distance easy to produce spot lack. CONSTITUTION:The distance measurement device is provided with a light emission means 1 for emitting light toward a distance measurement objective and a first light receiving means 2A and a second light receiving means 2B for sandwiching the light emission means 1 on both sides. Discrimination is performed on whether a distance measurement objective is easy to erroneously measure a distance by means of an output signal of the light receiving means 2 and, if the discrimination is performed on whether erroneous distance measurement is easily done by spot lack and the like, a light emission quantity of the light emission means, namely, the number of light emissions a light emission time is increased to execute the distance measurement for the purpose of increase of distance measurement precision.

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, more specifically,
The present invention relates to a trinocular active distance measuring device in which light receiving means is arranged on both sides of the light projecting means.

[0002]

2. Description of the Related Art Conventionally, an active distance measuring apparatus projects infrared light from a light projecting means onto a subject and forms an image of reflected light from the subject onto a light receiving element which is a light receiving means. The distance from the image position to the subject is calculated based on the principle of triangulation. However, in this distance measuring device, for example, the projection spot extends over a distant subject,
There is a drawback that erroneous distance measurement is caused when a so-called spot defect occurs, or when the projected spot extends over an object having a large contrast difference.

In order to solve this problem, a distance measuring device disclosed in Japanese Patent Laid-Open No. 1-217425 has been proposed. This device is a three-lens distance measuring device in which two light receiving means are arranged on both sides of the light projecting means.
As shown in FIG. 8, the spot light from the IRED 7 of the light emitting element driven by the light emitting circuit 35 is emitted through the light projecting lens 8, reflected by the subject 9, and received by the light receiving lenses 6A and 6B arranged on both sides. A spot image is formed on the two-divided PSD (position detecting element) 5A, 5B via the above. Above PSD
Of the output currents of 5A and 5B, if the output currents on the inner side (light emitting element 7 side) are I11 and I21, and the output currents on the outer side are I12 and I22, the currents input to the amplifiers 36A and 36B are, respectively. I12 + I22, I11 + I21. Therefore, the outputs IA, IB of the amplifiers 36A, 36B are
Is IA = k.multidot. (I12 + I22) and IB = k.multidot. (I11 + I21). k represents the amplification factor.

These outputs IA and IB have the following relationship depending on the object distance. That is, at long distances, IA <IB, at predetermined distances, IA = IB, and at short distances, IA> IB. The outputs IA and IB are input to the calculating means 37, and IA / (IA + IB), IA / IB, (IA-IB).
A ratio calculation such as / (IA + IB) is performed to generate a subject distance signal. Therefore, if a spot defect occurs, the output I12 increases and decreases, the output I21 increases and decreases, and the output I11 increases and decreases I.
22 increases / decreases at the same rate in opposite directions. Therefore, according to this apparatus, the relationship between the outputs IA and IB does not change, and the error in the distance measurement data due to the spot missing does not occur.

Next, a state in which a spot defect has occurred in this three-lens distance measuring device will be described with reference to the optical path diagram of FIG. The structure of the light emitting and receiving means of FIG. 9 is the same as that of FIG. The distance between the light projecting lens 8 and the subject 9 is L, the distance between the principal points of the light projecting lens 8 and the light receiving lenses 6A and 6B, that is, the base line length is s, and the focal length of the light receiving lenses 6A and 6B is f. And Further, the position of the center of gravity of the reflected light of the spot image on the PSD 5A, 5B is represented by x with the optical axis of the light receiving lens 6A, 6B as the origin. This value x gives the output currents I12, I22, I11 and I21. Now, when no spot omission occurs, that is, when the reflected light barycentric position in the case where all the projected spots hit the subject is xo, the following formula is established. That is, 1 / LA = 1 / LB = xo / (s · f) (1) LA and LB indicate the distances between the light receiving lenses 6A and 6B and the subject 9, and the distances calculated respectively.

On the other hand, as shown in FIG. 9, when a spot defect occurs, a part a of the projected light spot hits the subject 9, and the rest falls in the background (distance ∞), The position of the center of gravity of the reflected light of the spots incident on the PSDs 5A and 5B is represented by the absolute value Δx of the deviation amount from the position xo.
If the above x is (xo−Δx) or (xo + Δx), then the values are equal to and deviate in the opposite direction for PSDs 5A and 5B. Indicated by. In addition, 5A 'and 5B' in FIG.
The top view of the spot image formation state on A and 5B is shown. 1 / LA = (xo-Δx) / (s · f) ……………… (2) 1 / LB = (xo + Δx) / (s · f) …………… (3 ) Then, by obtaining the average value of the equations (2) and (3), the shift of the center of gravity of the reflected light due to the lack of the spot is offset,
Correct distance measurement data, which is the same as when there is no spot missing, is required. Then, the subject distance L is represented by 1 / L = (1 / LA + 1 / LB) / 2 = xo / (s · f) .................... (4)

[0007]

However, the three-lens range finder disclosed in the above-mentioned Japanese Patent Laid-Open No. 1-217425 has an amount of received light in comparison with a normal two-lens range finder of the same size. Is doubled, but the baseline length is 1/2, and basically the ranging accuracy is not improved. Then, when the degree of spot chipping is very large, the amount of reflected light is reduced, so that it is not possible to completely prevent the accuracy from being degraded due to the spot chipping. Further, the size of the projected spot becomes larger as the subject becomes farther away, and the spot chipping is likely to occur. Further, since the amount of reflected light from the subject decreases in inverse proportion to the square of the distance, there is a problem that accurate distance measurement data cannot be obtained in the case of a spot defect of a long-distance subject.

The present invention has been made in order to solve the above-mentioned problems, and enables accurate distance measurement even if a spot defect occurs on a long-distance subject or if the spot defect is large to some extent. An object of the present invention is to provide a distance measuring device that can be used.

[0009]

As shown in the conceptual diagram of FIG. 1, a distance measuring device of the present invention includes a light projecting means 1 for emitting light toward a distance measuring object, and both sides of the light projecting means sandwiching the light projecting means. Each of them is arranged with a baseline length, and receives the reflected light from the object to be measured,
First and second light receiving means 2A, 2B which respectively output signals corresponding to the distance to the distance measurement target according to the light receiving position.
Then, using the output signals of the first and second light receiving means 2A and 2B, a determining means 3 for determining whether or not the distance measuring object is likely to be erroneously measured, and a normal distance measuring operation. In order to obtain a highly accurate distance measurement result, a first control mode for controlling the light projecting means for increasing the number of times of light projection or a longer light projection time than that of the first control mode is used. It is characterized in that it is provided with a projection control means 4 having two control modes.

[0010]

When the distance measuring operation is started, the first control mode is executed, the light from the light projecting means 1 is projected onto the object, and the reflected light is received by the first and second light receiving means 2A and 2B. As a result, when the determination means 3 determines that the distance measurement target is likely to be erroneously measured, the second control mode is subsequently executed,
Distance measurement is performed. In this case, the number of times of light projection is increased or the light projection time is lengthened to obtain a highly accurate distance measurement result.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 2 is a main block configuration diagram of the distance measuring apparatus showing the first embodiment of the present invention. The distance measuring device has the light emitting / receiving unit shown in FIGS. That is, based on a light emission timing signal T1 from the control means 40, which will be described later, an IR that emits an infrared spot light toward the subject 9 that is a distance measurement target.
A light projecting means including an ED 7 and a light projecting lens 8 and a light emitting means disposed on both sides of the light projecting means with a predetermined base line length therebetween.
Light receiving lenses 6A, 6 for receiving the reflected light from the subject 9
B and the first and second light receiving means, each of which is located behind the lens and outputs a signal corresponding to the distance to the object to be measured according to the light receiving position, by the first and second light receiving means. Parts are composed.

Further, the present distance measuring apparatus includes preamplifiers 10A, 11A, 10B and 11B for amplifying the photocurrent outputs of the PSDs 5A and 5B, as rational components other than the light emitting / receiving unit, and a ratio calculation for performing a ratio calculation of the outputs. Circuits 31A and 31B and a judging means for judging whether or not the object 9 is likely to be erroneously distance-measured, which is a value obtained from the result of the ratio calculation, and is a value of the spot on the image plane. A spot defect determination unit 30 that performs the above determination by performing a level determination using a spot defect coefficient D (described later) indicating the degree of defect, and a first unit that controls the light projecting unit for a normal distance measuring operation. Control mode and two distance measurement modes of the second control mode in which a high-accuracy distance measurement result is obtained by increasing the number of times of light emission of the IRED 7 or increasing the light emission time as compared with the first control mode. Having And a control unit 40 which is a control means.

Next, the ratio calculation processing in the ratio calculation circuits 31A and 31B will be described in detail. It should be noted that the optical path diagram of the light emitting / receiving unit of FIG. First, P
Let SD be the total length of SD5A, 5B, t be the photocurrent output of each end, and PSD5A, 5B as shown in FIG.
The position of the center of gravity of the reflected light of the spot image on B is determined by the light receiving lens 6
When x is the origin of the optical axes of A and 6B, I1 / I2 = x / (t-x). Then, when the subject distances LA and LB are represented by L and the image forming position xo is x, and the equation (1) is substituted,
The following formula is obtained. That is, I1 / (I1 + I2) = sf / (t.multidot.L) ... (5), and the ratio calculation circuit 3 calculates the ratio of I1 / (I1 + I2).
The object distance L is uniquely obtained by performing 1A and 31B.

Further, the spot chipping coefficient D, which is data for the level judgment by the spot chipping judging means 30, is
Similarly, the absolute value of the difference between the values 1 / LA and 1 / LB in the equations (2) and (3) calculated by the ratio calculation circuits 31A and 31B is obtained. That is, D = | 1 / LA −1 / LB | = 2 · Δx / (s · f) …………………………………… (6). The coefficient D is a value proportional to the shift amount Δx of the reflected light barycentric position of the spot in FIG. 9 as shown in the equation (6). Therefore, the magnitude of this value indicates the degree of lack of the spot in the direction of the base line length. When the spot is largely missing, that is, when the D value is large, the amount of reflected light from the subject 9 is greatly reduced. At that time, when the subject 9 is at a long distance, the reflection is reduced. The amount of light decreases further,
The ranging accuracy will be greatly reduced. Then, the spot defect determination means 30 compares the spot defect coefficient D with a predetermined value, and if the coefficient D is large, it is determined that the subject 9 is likely to be erroneously distance-measured and outputs the result to the control means 40.

Next, the distance measuring operation of the distance measuring device of the present embodiment having the above-mentioned structure will be described. The control means 40
First emits a light emission timing signal T1 to cause the IRED 7 to emit light, and causes the IRED 7 to emit light a predetermined number of times in the first control mode. Then, the ratio calculation circuits 31A and 31B perform ratio calculation processing. Then, the spot missing determination means 30
Then, the value of the coefficient D is obtained, and the level is determined. When the D value is smaller than a predetermined value, it is determined that the error of the subject distance L obtained by the ratio calculation processing is small, and the distance measurement by the ratio calculation is set as a final value to complete the distance measurement. .. However, when the D value is larger than the predetermined value, the error of the subject distance L obtained by the ratio calculation processing in the first mode is large,
Since the accuracy of distance measurement is expected to deteriorate, distance measurement is executed in the second control mode. In the distance measurement operation in the second control mode, the IRED 7 in the first control mode is caused to emit light more times than the number of times of light emission, or the light emission time of one time is made longer to reduce the distance measurement time. Although it becomes long, the value taken in by the ratio calculation processing is set to a large value to improve the ranging accuracy.

Since the distance measuring apparatus of the present embodiment detects the spot defect coefficient D and selects the distance measuring mode as described above, the distance measuring accuracy is affected by any chance. Even if such a spot defect occurs, the distance measurement mode is automatically selected, the distance measurement accuracy is improved, and the distance measurement is performed, so that the distance measurement can be executed regardless of the spot defect. In the electric circuit of the distance measuring apparatus according to the second embodiment of the present invention shown in FIG. 4, which will be described later, the electric circuit excluding the light quantity integrating circuit is
It can be applied to the distance measuring apparatus of the first embodiment as it is.

Next, a distance measuring device showing a second embodiment of the present invention will be described with reference to the main block diagram of FIG. In the distance measuring device of the first embodiment, the determination means is composed only of the spot lack determination means 30. In this distance measuring apparatus, as the determination means 34, a light amount determination means 32 is added in addition to the spot lack determination means 33. Then, the control unit 41, which is the light emission control unit, selects one of the distance measurement modes based on the result of both the spot defect determination result of the spot defect determination unit 33 and the determination result of the reflected light intensity information of the light intensity determination unit 32. Either the first control mode or the second control mode is selected. In addition, IRED7, PSD5A, 5
The light projecting / receiving unit composed of B and the like is the same as that of the first embodiment.

The light quantity discriminating means 32 is the preamplifier 10
The output currents of A, 11A, 10B, and 11B are all added and compared with a predetermined value. The amount of reflected light from the subject incident on the PSDs 5A and 5B is detected, and the subject 9 is detected.
Is a short distance or a long distance, or whether or not the reflection state of the subject is good. By using the information of the reflected light amount for the determination, for example, a spot defect is large, an accurate distance measurement result can be obtained even when the subject 9 is at a relatively long distance, and the spot defect is large. Also, when the subject 9 is located at a relatively short distance and a sufficient amount of light is obtained, the distance measurement mode is set as the second control mode, and the first control is performed without wasting time. It is possible to perform distance measurement by the mode and obtain sufficient distance measurement accuracy.

FIG. 4 is an electric circuit diagram of the distance measuring apparatus of this embodiment, and the configuration of the distance measuring apparatus will be described in more detail with reference to this drawing. However, since the light emitting and receiving unit is the same as that in FIG. 3, description thereof will be omitted. In this measuring device, I
Preamplifier 10 for amplifying photocurrent of RED 5A, 5B
A, 11A and 11A, 11B have low input impedance, and separate the photocurrent component due to the stationary light and amplify only the signal light component. The preamplifier 10
The output currents of A, 11A and 11A, 11B are logarithmically compressed by the compression diodes 12A, 13A, 12B, 13B, respectively, and the buffers 14A, 15A,
It is input to the ratio calculation circuits 31A and 31B via 14B and 15B. Further, the outputs of the preamplifiers 10A and 11A and 11A and 11B are combined into a single light quantity integration circuit including an integration amplifier 24 and an integration capacitor 25 for obtaining reflected light quantity information via an analog switch 28. Is entered. A current source 26 is connected to the capacitor 25.

The ratio calculation circuit 31A is composed of two NPN transistors 17A and 18A and a current source 19A. The ratio calculation circuit 31B is also composed of two NPN transistors 17B and 18B and a current source 19B. Integrating capacitors 20A and 20B and current sources 21A and 21B are connected to the ratio calculation circuits 31A and 31B, respectively. In addition, the integration capacitors 20A, 2
0B, and the integrating capacitor 25 has a reset circuit 2 for resetting the potential to the initial state each time it is measured.
2 are connected to each other. This reset circuit 22
Are controlled by the control circuit 23.

The output voltages of the ratio calculation circuits 31A and 31B are taken into the control circuit 23 as distance measurement information through the integration capacitors 20A and 20B, and the output voltage of the light amount integration circuit is passed through the integration capacitor 25. Similarly, the light amount information is captured by the control circuit 23. Further, the timing circuit 27 is controlled by the control circuit 23 and emits a light emission signal T1 for giving the light emission timing of the IRED 7 and current sources 19A, 19B, 21A, 21B, 2
Timing signals T2, T3, T4, T5 for controlling the ON / OFF of the analog switch 6, and a timing signal T for controlling the ON / OFF of the analog switch 28.
6 is output.

When the current sources 19A and 19B are turned on by the timing signal T2 in synchronization with the light emission of the IRED 7 in the ratio calculation circuits 31A and 31B, the integrated current I
intA and IintB are the relations of IintA = {I1A / (I1A + I2A)} · Io ……………… (7) IintB = {I1B / (I1B + I2B)} · Io ……………… (7) ′ Therefore, VintA = {I1A / (I1A + I2A)}. Io.n..tau. / C ... (8) VintB = {I1B / (I1B + I2B)}. Io.n.τ in the integrating capacitors 20A and 20B. The integrated voltage signal of / C ... (8) 'is generated. Where I1A and I1B are
The photocurrent output of the PSDs 5A and 5B is outside the IRED7, and I2A and I2B are the IR of the PSDs 5A and 5B.
The photocurrent output on the ED7 side, Io, is the current source 19A, 19B
Is the current value of. In addition, n is the IRE per measurement
The number of times of light emission of D7, τ is the integration time of one light emission, and C is
It is the capacitance value of the integrating capacitors 20A and 20B. In addition,
The reset circuit 22 initializes the potentials of the integration capacitors 20A and 20B and sets the integration voltages VintA and VintB to 0 prior to the light emission of the IRED 7. Then, the control circuit 23 obtains the inverse integration time corresponding to the distance by the inverse integration operation of the integrated voltages VintA and VintB by the current sources 21A and 21B started by the timing signals T3 and T4, and P
It is stored as distance measurement data 1 / LA, 1 / LB which is the reciprocal of each measurement distance by SD5A, 5B.

On the other hand, in the light quantity integrating circuit, the IR
The output voltage Vpint of the integrating amplifier 24 is reset to the initial state by the reset circuit 22 prior to the light emission timing of the ED 7. Then, the analog switch 28 is turned on by the timing signal T6, the amplified outputs of the PSDs 5A and 5B are input to the integrating amplifier 24 and the integrating capacitor 25, and integration is performed. The integrated output voltage Vpint becomes Vpint = nK (I1A + I2A + I1B + I2B) / Cp (9). Here, K is the amplification factor of the preamplifier 10A or the like,
Cp is the capacitance value of the integrating capacitor 25. The integrated output voltage Vpint in the above equation (9) is inversely integrated by the current source 26, and the inverse integration time is A /
It is D-converted and read by the control circuit 23.

Here, on the assumption that the amount of light reflected from the subject 9 is constant and the projection spot of the IRED 7 hits the subject, it is inversely proportional to the square of the subject distance Lc. The distance measurement data 1 / Lc corresponding to the amount of reflected light can be represented by 1 / Lc = Ko. (I1A + I2A + I1B + I2B) ^1/2 (10). Here, Ko is a proportional constant. The control circuit 23 can obtain the distance measurement data 1 / Lc corresponding to the reflected light amount from the expressions (9) and (10). This distance measurement data 1 / Lc largely depends on the reflectance of the subject 9 and changes greatly due to spot defects, but in the present embodiment, it is used as information for detecting the degree to which the subject is located at a long distance.

Next, the distance measuring operation of the distance measuring apparatus of this embodiment will be described with reference to the flow chart of FIG. 5 and the time charts of FIGS. FIG. 6 shows a time chart of the distance measuring operation in the first control mode in the distance measuring mode, and FIG. 7 shows a time chart in the second control mode executed subsequent to the distance measuring operation of FIG. The time chart of distance operation is shown.

First, the distance measurement in the first control mode of the distance measurement modes is executed in steps S1 to S3. That is, as shown in FIGS. 6A, 6B, and 6I, the IRED 7 is caused to emit light a predetermined number of times by the light emission signal T1, and the timing signal T2 is generated only during the light emission period.
At T6, the current sources 19A and 19B and the analog switch 28 are turned on only No times. As a result, a signal current flows through the integrating capacitors 20A, 20B and 25 and is accumulated as an integrated voltage ((c) in FIG. 6,
(D), (j), step S1). When No times of light emission and integration are completed, a timing signal T which is an inverse integration signal
3 is output to the current source 21A ((e) in FIG. 6),
The inverse integration of the integration capacitor 20A is executed. at the same time,
A counter (not shown) starts counting inside the control circuit 23. When the inverse integration is completed, the count value is stopped, and the count value is taken into the control circuit 23 as A / D converted distance measurement data 1 / LA ((f) in FIG. 6). Then, similarly, the timing signal T4, which is an inverse integration signal, is output to the current source 21B ((g) in FIG. 6), and the inverse integration of the integration capacitor 20B is executed. At the same time, A / D conversion is performed by the counter and the distance measurement data 1 / LB is taken into the control circuit 23 ((h) in FIG. 6). Further, the timing signal T5, which is an inverse integration signal, is output to the current source 26 ((k) in FIG. 6), and the light amount inverse integration of the integration capacitor 25 is executed. At the same time, A / D conversion is performed by the counter, and the value is fetched by the control circuit 23 as the distance measurement data 1 / Lc corresponding to the reflected light amount ((l) in FIG. 6). The above operation is performed in step S2.

Next, in step S3, the control circuit 23
Then, the spot defect coefficient D is calculated by the equation (6) based on the distance measurement data. Then, in step S4, the coefficient D is compared with a predetermined spot missing coefficient Do.
Is not large, that is, if the degree of spot missing is within an allowable range, the process jumps to step S8 and 1 / LA, 1 / LB of the distance measurement data in the first control mode is performed.
The average value (1 / LA + 1 / LB) / 2 is set as the final distance measurement value, and this distance measurement processing is terminated. In addition, the above step S
In the determination of 4, if the coefficient D is larger than the coefficient Do, that is, if the degree of spot missing exceeds a certain allowable range, the process proceeds to step S5, and the distance measurement data 1 / Lc corresponding to the reflected light amount is further acquired. If the distance measurement data 1 / Lc is not smaller than the predetermined distance measurement data 1 / Lo, the subject is located at a relatively short distance, and although the spot is missing, the distance measurement accuracy is sufficient. It is judged to be high, and the process jumps to step S8 in the same manner as described above, and the average value of 1 / LA and 1 / LB of the distance measurement data in the first control mode (1
/ LA + 1 / LB) / 2 is set as the fixed distance measurement value.

If the distance measurement data 1 / Lc corresponding to the reflected light amount is smaller than the data 1 / Lo in the determination in step S5, the subject is located at a relatively long distance,
In addition, since the spot is missing, it is determined that sufficient distance measurement accuracy cannot be obtained as it is, and the process proceeds to step S6. Step S6 and step S7
Then, the distance measurement processing in the second control mode of the distance measurement modes is performed. In the second control mode, the number of times of light emission of the IRED 7 is set to be larger than that in the first mode, light is emitted only 2No times to compensate for the insufficient light amount, and the data of double the distance measurement accuracy is obtained.

FIG. 7 is a time chart in the second control mode. In step S6, the IRED 7 repeats light emission for 2No times in response to the light emission timing signal T1 ((a) in FIG. 7). Only during the light emission period, the current sources 19A and 19B are turned on 2No times by the timing signal T2 ((b) of FIG. 7). As a result, a signal current flows through the integrating capacitors 20A and 20B and is accumulated as an integrated voltage ((c) and (d) in FIG. 7, step S6). When 2No times of light emission and integration are completed, the timing signal T3, which is an inverse integration signal, is output to the current source 21A ((e) in FIG. 7), and the inverse integration of the integration capacitor 20A is executed (step). S7). At the same time, the counter (not shown) starts counting inside the control circuit 23. When the inverse integration is completed, the count value is stopped, and the count value is taken into the control circuit 23 as A / D converted distance measurement data 1 / LA ((f) in FIG. 7). Then, similarly, a timing signal T4 which is an inverse integration signal is output to the current source 21B (see FIG. 7).
(G)), the inverse integration of the integrating capacitor 20B is executed. At the same time, A / D conversion is performed by the counter and the distance measurement data 1 / LB is taken into the control circuit 23 (FIG.
(H)). Succeedingly, in a step S8, based on the distance measurement data 1 / LA and 1 / LB, the average value (1 / LA
+ 1 / LB) / 2 is obtained and used as the final distance measurement value.

As described above, in the distance measuring apparatus according to the present embodiment, the distance measuring data 1 / Lc corresponding to the reflected light quantity is separately fetched as compared with the distance measuring apparatus according to the first embodiment. Even if a spot defect occurs, the distance measurement in the second control mode is not performed, and the distance measurement with higher accuracy can be executed more efficiently. In the second control mode of the device of this embodiment, the number of times of light emission is set to be larger than the number of times in the first mode in order to improve the distance measurement accuracy, but it is set to increase the light emission time instead of the number of times. Even if it is, the same effect can be obtained.

[0031]

As described above, the distance measuring apparatus of the present invention is provided with the light projecting means for emitting light toward the object to be measured and the first and second light receiving means on both sides of the light projecting means. By using the output signal of the light receiving means, it is determined whether or not the object to be measured is likely to be erroneously measured, and the distance is increased by increasing the light projection amount of the light emitting means only when the distance is easily erroneously measured. Since the accuracy of the present invention is improved, even if a spot defect occurs due to the condition of the subject, or even a long-distance subject where the spot defect is likely to occur, the distance measurement with high precision is achieved. It is possible to have a remarkable effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing the concept of the present invention.

FIG. 2 is a block configuration diagram of a distance measuring device showing a first embodiment of the present invention.

FIG. 3 is a block configuration diagram of a distance measuring device showing a second embodiment of the present invention.

FIG. 4 is an electric circuit diagram of the distance measuring device of FIG.

5 is a flowchart of the distance measuring process of the distance measuring device of FIG.
To.

6 is a time chart in the first control mode in the distance measuring operation of the distance measuring device of FIG.

7 is a time chart in the second control mode in the distance measuring operation of the distance measuring device of FIG.

FIG. 8 is a main block configuration diagram of a conventional three-lens distance measuring device.

FIG. 9 is an optical path diagram of a distance measuring optical system of the three-lens distance measuring device.

[Explanation of reference numerals] 1 ……………………… Projection means 2A ……………… First light receiving means 2B ……………… Second light receiving means 3, 34 ………… Judgment means 4 …………………… Projection control means 5A ……………… PSD (first light receiving means) 5B ……………… PSD (second light receiving means) 6A ……………… (First light receiving means) 6B ……………… Light receiving lens (second light receiving means) 7 …………………… IRED (light emitting means) 8 …………………… Light means 23 23 Control circuit (judging means, light emission control means) 24 Integral amplifier (judging means) 25 Integral condenser (judging means) 30, 33 ...... Spot lack determination means (determination means) 32 ............ Light intensity determination means (determination means) 40, 41 ...... Control means (light projection control means) 23 ............... control circuit (determination means, projecting control means) the process of step S1,2 ............... first processing step S6, 7 ............... second control mode of the control modes

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[Procedure amendment]

[Submission date] April 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

In order to solve this problem, a distance measuring device disclosed in Japanese Patent Laid-Open No. 1-217425 has been proposed. This device is a three-lens distance measuring device in which two light receiving means are arranged on both sides of the light projecting means.
As shown in FIG. 8, the spot light from the IRED 7 of the light emitting element driven by the light emitting circuit 35 is emitted through the light projecting lens 8, reflected by the subject 9, and received by the light receiving lenses 6A and 6B arranged on both sides. 2-split SPD (silicone
Diode) A spot image is formed on 5A and 5B.
Of the output currents of the SPDs 5A and 5B, if the output currents on the inner side (light emitting element 7 side) are I11 and I21 and the output currents on the outer side are I12 and I22, respectively, the amplifier 36
The currents input to A and 36B are I12 + I22,
It becomes I11 + I21. Therefore, the outputs IA and IB of the amplifiers 36A and 36B are as follows: IA = k. (I12 + I22) IB = k. (I11 + I21) k represents the amplification factor.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

When the distance measuring operation is started, the first control mode is executed, the light from the light projecting means 1 is projected onto the object, and the reflected light is received by the first and second light receiving means 2A and 2B. As a result, when the determination means 3 determines that the distance measurement target is likely to be erroneously measured, the second control mode is subsequently executed,
Measuring a distance, but in this case, either increasing the light projection count, by increasing the light projecting time, so as to obtain a measurement result with high accuracy.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Since the distance measuring apparatus of the present embodiment detects the spot defect coefficient D and selects the distance measuring mode as described above, the distance measuring accuracy is affected by any chance. Even if such a spot defect occurs, the distance measurement mode is automatically selected, the distance measurement accuracy is improved, and the distance measurement is performed, so that the distance measurement can be executed regardless of the spot defect. In the electric circuit of the distance measuring device according to the second embodiment of the present invention shown in FIG. 4, which will be described later, the electric circuit excluding the light amount integrating circuit can be directly applied to the distance measuring device according to the first embodiment. Is.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

FIG. 4 is an electric circuit diagram of the distance measuring apparatus of this embodiment, and the configuration of the distance measuring apparatus will be described in more detail with reference to this drawing. However, since the light emitting and receiving unit is the same as that in FIG. 3, description thereof will be omitted. In this measuring device, P
Preamplifier 10A for amplifying photocurrent of SD 5A, 5B,
11A, 10B , and 11B have low input impedance, and separate the photocurrent component due to the stationary light and amplify only the signal light component. The preamplifier 10A,
The outputs of 11A, 10B, and 11B are logarithmically compressed in their output currents by compression diodes 12A, 13A, 12B, and 13B, respectively, and buffers 14A, 15A, and 14B.
It is input to the ratio calculation circuits 31A and 31B via B and 15B. Further, the preamplifiers 10A and 11A, and
The outputs of 10B and 11B are combined into one, and input via an analog switch 28 to a light quantity integrating circuit including an integrating amplifier 24 and an integrating capacitor 25 for obtaining reflected light quantity information. A current source 26 is connected to the capacitor 25.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

If the distance measurement data 1 / Lc corresponding to the reflected light amount is smaller than the data 1 / Lo in the determination in step S5, the subject is located at a relatively long distance,
In addition, since the spot is missing, it is determined that sufficient distance measurement accuracy cannot be obtained as it is, and the process proceeds to step S6. Step S6 and step S7
Then, the distance measurement processing in the second control mode of the distance measurement modes is performed. In the second control mode, the number of times of light emission of the IRED 7 is set to be larger than that in the first mode, light is emitted only 2No times to compensate for the insufficient light amount, and data with a distance measurement accuracy of 2 ^1/2 times is obtained.

Claims (1)

[Claims] 1. A light projecting means for emitting light toward a distance measuring object, and light-transmitting means which are arranged on both sides of the light projecting means with a baseline length therebetween to receive and receive the reflected light from the distance measuring object. The distance measuring object is detected by using the first and second light receiving means for outputting signals corresponding to the distance to the distance measuring object according to the position and the output signals of the first and second light receiving means. Judgment means for judging whether or not the distance is apt to be erroneously measured, a first control mode for controlling the light projection means for a normal distance measurement operation, and light projection as compared with the first control mode. It has a second control mode that obtains a highly accurate distance measurement result by increasing the number of times or prolonging the light projection time, and the first control mode is executed when the distance measurement operation starts When it is determined that the distance measurement target is erroneously measured by the determination means, Then the distance measuring apparatus for a light projection control means, characterized by comprising performing a second control mode.