JPH06241786A - Range finder - Google Patents

Abstract

PURPOSE:To prevent the range finding from being made impossible and prevent the reduction of the ranging precision. CONSTITUTION:A ranging device is provided with a distance estimating means 5 estimating whether a ranging object is located at a far distance or at a near distance and a signal switching means 4 switching the signal used for the first integration in an arithmetic means 6 within two kinds of signals A, B from a light receiving means 2 in response to the estimated result by the distance estimating means 5. Whether the ranging object is located at the far distance or at the near distance is estimated in response to the signal level of either one of two kinds of signals from the light receiving means 2 or in response to the positional information from an operating means externally inputting the positional information of the ranging object, and the signal used for the first integration in the arithmetic means 6 is switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving means for receiving reflected light of a projected light from a light projecting means on a distance measuring object and outputting two kinds of signals depending on the distance, and the light receiving means. The present invention relates to an improvement of a distance measuring device provided with a calculating means for integrating one signal and integrating it in the opposite direction by both signals to calculate distance measuring data.

[0002]

2. Description of the Related Art Heretofore, various proposals have been made for active range-finding devices to improve the range-finding accuracy and expand the range.

For example, in a distance measuring device that measures the distance to an object by projecting light on the object and receiving the reflected light (signal light), saturation of the received light signal (dynamic range) is taken. As such, there has been proposed a device provided with a means for controlling the intensity of the projection energy of the projection means (projection power) and for controlling the amplification factor and integration time of the light receiving means. Further, there is also proposed a device provided with a means for determining whether or not the distance measurement result is valid based on the intensity of the received light signal.

These conventional examples will be described with reference to the flowchart of FIG.

Outputs A and B of a light receiving means such as a semiconductor position detector which projects light from a light emitting means such as an infrared light emitting diode toward a distance measuring object and receives reflected light from the distance measuring object. For example, in the distance measuring device that calculates the distance measuring information by double integration of A / (A + B), the intensity of the light receiving signal at the PSD when the distance measuring object is present at a short distance and a long distance is: Since the difference is several hundred times or more, accurate distance measurement information cannot be obtained using the same signal processing system.

Therefore, as shown in FIG. 7, first, the light projecting power of the light projecting means is set to the full state and light is projected toward the object to be measured (step 401), and then the output of the light receiving means at that time is output. It is determined whether or not the sum signal (A + B) is larger than a predetermined value, and when it is determined that the sum signal (A + B) is larger (when the object to be measured is on the short distance side), the signal processing system (amplifier, etc.) Since it will be saturated, the projection power will be saved. Then, the sum signal (A + B) of the output of the light receiving means is again compared with a predetermined value, and such an operation is repeated until the sum signal (A + B) of the output becomes equal to or less than the predetermined value (step 402 → 4).
03 → 402).

When the sum signal (A + B) of the outputs of the light receiving means becomes less than a predetermined value, the saturation of the signal processing system can be prevented. Therefore, the outputs A and B are used to perform the distance measurement calculation of A / (A + B). Then, the distance information is calculated (step 40).
5).

Next, in order to improve the reliability of the obtained distance measurement information, the strength of the signal of the numerator (output A) in the above equation is determined to check whether the distance measurement information is valid. As a result,
If it is determined that it is not valid, infinite determination is performed. By performing such a determination, it is possible to improve the ranging accuracy.

[0009]

However, in the above distance measuring device, since the distance measuring information is calculated by the integration of A / (A + B), the reflected light from the distance measuring object is received by the light receiving means. When the image is formed at the edge, the difference between the output of A and the output of B is large, and the projection power depends on the output of which is stronger.

Therefore, when the object to be measured is in the vicinity, it becomes impossible to measure the distance due to the integration method or the like even though it is within the range, or the lens is set to the infinite position by infinity determination. However, there is a problem in that the distance measurement accuracy is degraded.

(Object of the Invention) An object of the present invention is to provide a distance measuring device which can prevent the distance measuring from being impossible and the distance measuring accuracy from being lowered.

[0012]

According to the present invention, a distance estimating means for estimating whether a distance measuring object is located at a long distance or a short distance and an estimation result of the distance estimating means are provided. A signal switching means for switching the signal used for the first integration in the arithmetic means out of the two kinds of signals from the light receiving means,
Depending on the signal level of either one of the two types of signals from the light receiving means, or according to the position information from the operating means for externally inputting the position information of the distance measuring object, It is estimated whether it is located at a long distance or a short distance, and the signal used for the first integration in the calculation means is switched.

Further, when two kinds of signals from the light receiving means are compared at different discrimination levels, and as a result of the discrimination, it is estimated that the object to be measured has a predetermined distance, it is set in advance. Distance measuring data setting means for setting the distance measuring data as final distance measuring data is provided, and is set in advance when it is estimated that the distance measuring object is a predetermined distance from the two kinds of signals from the light receiving means. The measured distance data is set as the final distance measurement data.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a block diagram showing the schematic arrangement of a distance measuring apparatus according to the first embodiment of the present invention. In the figure, 1 is an infrared light emitting diode (hereinafter, IR) which is a light projecting means.
ED). Reference numeral 2 denotes a semiconductor position detector (hereinafter referred to as PSD), which is a light receiving means, and outputs a signal A that is greater as the object to be measured is located closer to the short distance (N) side and a long distance ( It has an output end 2b that outputs a larger signal B toward the F) side. 3 is a projection power control circuit for controlling the projection power of the IRED 1 and 4 is the PSD 2
Sensor output switching circuit for switching which sensor output of the output terminal 2a or 2b of the
Is a level determination circuit for determining whether or not the sensor output selected by the sensor output switching circuit 4 is at a predetermined level. Reference numeral 6 denotes a microcomputer (hereinafter, referred to as a microcomputer) that controls the light projection power control circuit 3 based on a signal from the level determination circuit 5 and controls switching of the sensor output switching circuit 4. Reference numeral 7 denotes a range-finding range switching switch for setting whether the short-distance side photographing or the long-distance side photographing is performed.

FIG. 2 is an enlarged view of the PSD 2, and 8 is a PSD when the object to be measured is located on the near side.
2 is a reflection image on 2.

Next, the operation of the microcomputer 6 when obtaining the distance measurement information will be described with reference to the flowchart of FIG. [Step 101] The current flowing to the IRED1 which is the light projecting means is maximized via the light projecting power control circuit 3, and the IR
Turn on ED1. [Step 102] The sensor output switching circuit 4 is controlled so that the sum signal (A + B) of the outputs of the PSD 2 serving as the light receiving means is input to the level determination circuit 5. [Step 103] The judgment result by the level judgment circuit 5 for judging whether the sum signal (A + B) selected in the above step 102 is at a predetermined first level is judged, and the judgment result at this time is a predetermined value. If it is equal to or higher than the first level, the process proceeds to step 108, and if it is lower than the predetermined first level, the process proceeds to step 104. [Step 104] Here, PSD2 which is a light receiving means
The sensor output switching circuit 4 is controlled so that the output signal A of 1 is input to the level determination circuit 5. [Step 105] The determination result by the level determination circuit 5 for determining whether or not the signal A selected in the above step 104 is at the predetermined second level is determined, and the determination result at this time is the predetermined second level. If it is equal to or higher than the level, it is determined that the object to be measured is on the short-distance side and step 106
If it is below the predetermined second level, it is determined that the object to be measured is on the far side, and the process proceeds to step 109. [Step 106] Here, it is known to some extent that the object to be measured will be on the short distance side. Therefore, by setting the one with the stronger output signal to the numerator side, the distance measurement time is shortened and the accuracy is improved. Therefore, the distance calculation formula by double integration is set to A / (A + B), which is advantageous for the short distance side.
The center of gravity on SD2 is obtained, that is, the distance measurement information is calculated. [Step 107] It is determined whether or not the calculation result is a valid value based on the strength of the numerator signal of the above calculation formula, and if it is valid, the above calculation result is set as the distance measurement result and this operation is terminated. To do. On the other hand, if it is determined that it is not valid, the process proceeds to step 110.

If it is determined in step 102 that the sum signal (A + B) selected is equal to or higher than the predetermined first level, step 10 is performed as described above.
From 3 to step 108. [Step 108] Since the projection power of IRED1 is strong here, IRED1 is transmitted through the projection power control circuit 3.
To reduce the current to a little, reduce the projection power. And
It returns to step 103 again.

This operation (steps 103 → 108 → 10)
3) is the sum signal (A + B) in step 103.
Will be repeatedly executed while it is determined that is less than the first predetermined level.

If it is determined in step 104 that the signal A selected is less than the predetermined second level, it is determined from step 105 that the object to be measured is on the far side as described above. Go to step 109. [Step 109] Here, it is known to some extent that the object to be measured will be on the far distance side. Therefore, for the same reason as in the case of step 106, the distance calculation formula by the double integration is set on the far distance side. B / (A + B), which is advantageous to
With this, distance measurement information is calculated. Then, the process proceeds to the operation after step 107 described above.

If it is determined in step 107 that the calculation result is not valid, the process proceeds from step 107 to step 110 as described above. [Step 110] Since the calculation result is not valid here, and there is a problem in the size of the noise and the signal, it is determined that the distance measurement target is at an infinite position regardless of the calculation result, and the distance measurement information is determined. Is "infinite".

FIG. 4 shows the distance calculation formula as "A / (A + B)".
It is a figure which shows the integral waveform when it is set to "B / (A + B)", that is, when the arithmetic expressions are switched.

In the first embodiment, the magnitudes of the output signals A and B of the PSD 2 are checked, the distance of the large frame of the object to be measured (whether it is the short distance side or the long distance side) is discriminated, and Depending on the determination result, the distance measurement calculation formula is selected to be A / (A + B) or B / (A + B), and the distance measurement information is calculated by the selected calculation formula. It is possible to prevent a reduction in information calculation time and a reduction in distance measurement accuracy, and to prevent erroneous distance measurement such as infinity determination of a short distance object.

(Second Embodiment) FIG. 5 is a flow chart showing the operation of the distance measuring apparatus according to the second embodiment of the present invention, which will be described below. Since the circuit configuration of the distance measuring device in this embodiment is the same as that of the first embodiment, it is omitted here. [Step 201] The current flowing to the IRED1 which is the light projecting means is maximized through the light projecting power control circuit 3, and the IR
Turn on ED1. [Step 202] The sensor output switching circuit 4 is controlled so that the sum signal (A + B) of the outputs of the PSD 2 serving as the light receiving means is input to the level determination circuit 5. [Step 203] The determination result by the level determination circuit 5 that determines whether or not the sum signal (A + B) selected in the above step 202 is at a predetermined first level is determined. If it is equal to or higher than the first level, the process proceeds to step 210, and if it is lower than the predetermined first level, the process proceeds to step 204. [Step 204] Here, PSD2 which is a light receiving means
The sensor output switching circuit 4 is controlled so that the output signal A of 1 is input to the level determination circuit 5. [Step 205] The determination result by the level determination circuit 5 for determining whether or not the signal A selected in the above step 204 is at the predetermined second level is determined, and the determination result at this time is the predetermined second level. If it is equal to or higher than the level, it is determined that the object to be measured is on the short-distance side, and step 206
If it is below the predetermined second level, it is determined that the object to be measured is on the far side, and the process proceeds to step 208. [Step 206] Here, PSD2 which is a light receiving means
The sensor output switching circuit 4 is controlled so that the output signal B of 1 is input to the level determination circuit 5. [Step 207] The determination result by the level determination circuit 5 for determining whether or not the signal A selected in the above step 206 is at the predetermined third level is determined, and the determination result at this time is the predetermined third level. If it is below the level, the object to be measured is on the near side, and the process proceeds to step 211. If it exceeds the predetermined third level, the object to be measured is on the normal distance side and the process is to step 208. move on. [Step 208] Here, since it is known that the object to be measured is at the normal shooting distance, B / (A +
In step B), the center of gravity on the PSD 2 is obtained, that is, the distance measurement information is calculated. [Step 209] Based on the signal strength of the numerator of the above arithmetic expression, it is determined whether or not the arithmetic result is a valid value. To do. On the other hand, if it is determined that it is not valid, the process proceeds to step 212.

If it is determined in step 202 that the sum signal (A + B) selected is equal to or higher than the predetermined first level, step 20 is performed as described above.
From 3 to step 210. [Step 210] Since the projection power of the IRED1 is strong here, the IRED1 is transmitted via the projection power control circuit 3.
To reduce the current to a little, reduce the projection power. And
It returns to step 203 again.

This operation (step 203 → 210 → 20)
3) is the sum signal (A + B) in step 203.
Will be repeatedly executed while it is determined that is less than the predetermined first level.

If the signal A selected in step 206 is lower than the predetermined third level, it is determined that the object to be measured is on the near side, as described above, step 21.
Go to 1. [Step 211] Here, since it is clear that the object for distance measurement is in a close range, the distance measurement data is set to "close range" without performing the distance calculation.

If it is determined in step 209 that the calculation result is not valid, the process proceeds from step 209 to step 212 as described above. [Step 212] Since the calculation result is not valid here, the distance measurement information is set to "infinity".

In the second embodiment, the magnitudes of the output signals A and B of the PSD 2 are respectively examined, and when it is determined that the distance measuring object is at a close range, the distance measuring is performed. Since the distance measurement information is uniquely set to the "closest" without performing the calculation, it is possible to prevent an infinite determination as in the conventional case and a large blurred image. That is, it is possible to prevent erroneous distance measurement such as infinity determination of a short-distance object.

(Third Embodiment) FIG. 6 is a flow chart showing the operation of the distance measuring apparatus in the third embodiment of the present invention, which will be described below. Since the circuit configuration of the distance measuring device in this embodiment is the same as that of the first embodiment, it is omitted here. [Step 301] The current flowing to the IRED1 which is the light projecting means is maximized through the light projecting power control circuit 3, and the IR
Turn on ED1. [Step 302] Sum signal (A +) of each output of PSD2
B) is determined by the level determination circuit 5 for determining whether or not is at a predetermined first level. If the determination result at this time is equal to or higher than the predetermined first level, go to step 307. If it is less than the predetermined first level, the process proceeds to step 303. [Step 303] Here, the range-finding range selector switch 7
Is determined, and in the case of short-distance shooting, step 304
Go to step 305 if shooting on the far side. [Step 304] Here, it is clear that the object to be measured is on the short distance side. Therefore, for the same reason as in the first embodiment, the distance calculation formula by double integration is advantageous on the short distance side. As A / (A + B), the center of gravity on the PSD 2 is obtained, that is, distance measurement information is calculated. [Step 305] It is determined whether or not the calculation result is a valid value based on the signal strength of the numerator of the above calculation formula, and if it is valid, the above calculation result is set as the distance measurement result and this operation is ended. To do. On the other hand, if it is determined that it is not valid, the process proceeds to step 308.

If it is determined in step 302 that the sum signal (A + B) selected is higher than or equal to the predetermined first level, step 30 is performed as described above.
From 3 to step 307. [Step 307] Since the projection power of IRED1 is strong here, IRED1 is transmitted through the projection power control circuit 3.
To reduce the current to a little, reduce the projection power. And
It returns to step 302 again.

This operation (step 302 → 307 → 30)
2) is the sum signal (A + B) in step 302 above.
Will be repeatedly executed while it is determined that is less than the first predetermined level.

When it is determined in step 303 that the range-finding range switch 7 is in the long-distance side photographing, the range-finding target is on the long-distance side, and as described above, the process proceeds from step 303 to step 305. move on. [Step 305] Here, since it is clear that the object to be measured is on the far side, for the same reason as in the case of step 304, the distance calculation formula by double integration is advantageous on the far side. B / (A + B), and the distance measurement information is calculated accordingly. Then, the operation proceeds to the operation after step 306 described above.

If it is determined in step 306 that the calculation result is not valid, the process proceeds from step 306 to step 308 as described above. [Step 308] Since the calculation result is not valid here and there is a problem in the size of the noise and the signal, it is determined that the object to be measured is at an infinite position regardless of the calculation result, and the distance measurement information is determined. Is "infinite".

In the third embodiment, a switch (distance-measuring range changeover switch 7) capable of externally inputting whether the distance-measuring object is a short-distance side or a long-distance side is provided. Depending on the state of the switch, That is, it is roughly determined whether the object for distance measurement is on the near distance side or the far distance side, and whether the distance measurement arithmetic expression is A / (A + B) or B / (A + B) is determined according to the determination result. Since the distance measurement information is calculated according to the selected calculation formula, the time required to calculate the distance measurement information and the deterioration of the distance measurement accuracy are prevented, and errors such as infinite judgment of the short-distance measurement target are made. It becomes possible to prevent distance measurement.

[0036]

As described above, according to the present invention,
A distance estimating means for estimating whether the object to be measured is located at a long distance or a short distance, and an arithmetic means of the two kinds of signals from the light receiving means according to the estimation result of the distance estimating means. And a signal switching means for switching the signal used for the first integration in the above, and according to the signal level of either one of the two kinds of signals from the light receiving means, or the position information of the object to be measured is externally input. According to the position information from the operating means, it is estimated whether the object to be measured is located at a long distance or a short distance, and the signal used for the first integration in the calculating means is switched.

Therefore, it becomes possible to prevent the distance measurement from becoming impossible and to prevent the distance measurement accuracy from decreasing.

Further, when two types of signals from the light receiving means are compared at different discrimination levels, and as a result of the discrimination, it is estimated that the object to be measured has a predetermined distance, it is set in advance. Distance measuring data setting means for setting the distance measuring data as final distance measuring data is provided, and is set in advance when it is estimated that the distance measuring object is a predetermined distance from the two kinds of signals from the light receiving means. The measured distance data is set as the final distance measurement data.

Therefore, it is possible to prevent the distance measurement accuracy from deteriorating.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a distance measuring device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a PSD, which is a light receiving unit in FIG.

FIG. 3 is a flowchart showing an operation of the distance measuring device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing double integrated waveforms at a short distance and at a long distance in the first embodiment of the present invention.

FIG. 5 is a flowchart showing an operation of the distance measuring device according to the second embodiment of the present invention.

FIG. 6 is a flowchart showing an operation of the distance measuring device according to the third embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of a conventional distance measuring device.

[Explanation of symbols]

 1 IRED 2 PSD 3 Projection power control circuit 4 Sensor output switching circuit 5 Level determination circuit 6 Microcomputer 7 Distance measuring range switch A, B PSD output signal

Claims (5)

[Claims] 1. A light projecting means for projecting light toward an object to be measured, and a reflected light from the object to be projected of the light projected by the light projecting means to receive two kinds of signals depending on the distance. A distance measuring device including a light receiving unit for outputting and a signal calculating unit that integrates one signal from the light receiving unit and calculates the distance measuring data by integrating both signals in the opposite direction. Depending on the distance estimation means for estimating whether the object is located at a long distance or at a short distance, and an estimation result of the distance estimation means,
A distance measuring device comprising: a signal switching unit that switches a signal used for the first integration in the arithmetic unit from the two types of signals from the light receiving unit. 2. The distance estimating means estimates whether the distance measuring object is located at a long distance or a short distance according to the signal level of one of the two kinds of signals from the light receiving means. The distance measuring device according to claim 1, wherein the distance measuring device is means for performing. 3. The operating means for externally inputting the position information of the distance measuring object is provided, and the distance estimating means determines whether or not the distance measuring object is located at a long distance according to the position information from the operating means. The distance measuring device according to claim 1, wherein the distance measuring device is means for estimating whether the vehicle is located at a distance. 4. A light projecting means for projecting light toward a distance measuring object, and a reflected light of the light projected by the light projecting means reflected by the distance measuring object to receive two kinds of signals depending on the distance. In a distance measuring device comprising a light receiving means for outputting and a signal for integrating one signal from the light receiving means and for calculating distance measuring data by integrating in one direction with the two signals, The two types of signals from the means are respectively compared at different discrimination levels, and when it is estimated that the distance measurement target is a predetermined distance as a result of the discrimination, the preset distance measurement data is finally determined. Distance measuring device provided with a distance measuring data setting means for obtaining different distance measuring data. 5. The distance measuring device according to claim 4, wherein the predetermined distance of the object to be measured is a close distance, and the preset distance measuring data is a close distance data. .