JPH0798223A - Range finder - Google Patents

Abstract

PURPOSE:To prevent a range finder from becoming impossible to measure and lowering in accuracy by compensating distance information according to the level of light reception signal or the level of light reception signal and operation distance information. CONSTITUTION:An infrared ray light emitting diode 1 is driven via a light projection drive circuit 3 and is projected toward a subject. Then, it is set so that the signal of a semiconductor position detector (PSD) which is a sensor can be taken into receive reflection light from the subject, the ratio of signals output from both edges of a PSD 2 is calculated according to a specific operation by an operation means 6, and then operation data are calculated. Then, the intensity of the reception signal is judged by a signal level detection circuit 5 to judge whether any compensation is required or not. As a result, an operation is performed by the operation means 6 when the operation is required (when signal is weak), distance data are calculated and are compensated, and then the distance data are determined. On the other hand, when the reception light signal is strong, no compensation is made and operation data are used as distance data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a so-called active type distance measuring device which projects light toward a subject and obtains the distance of the subject by the reflected light.

[0002]

2. Description of the Related Art Conventionally, there is known a so-called active type distance measuring device which projects a light toward a subject and obtains the distance of the subject by the reflected light. This type of distance measuring device emits light and receives the reflected light, so that the level of the received light signal becomes very small for a long-distance subject or a subject with low reflectance. I was sick.

On the other hand, in the active type distance measuring method, it is necessary to supply a current to the light projecting means in order to project the light, so that the power supply fluctuation occurs accordingly.

Further, the projected light image may not be properly formed on the light receiving sensor due to the projection / reception optical system, or the blur amount may not be specified depending on the distance. Therefore, the distance measurement data sometimes deviates from the actual distance.

Further, the magnitude of the signal received on the electric circuit causes a response delay on the circuit, which may cause an error in the distance measurement data. In particular, this tendency has been remarkably exhibited when the distance of an object at a long distance or an object having low reflectance is measured and the level of the received light signal is low.

[0006] In order to solve this problem,
Japanese Patent No. 79320 discloses a technique of setting a predetermined distance (for example, infinite distance) without using the distance measurement data when the received light signal is below a predetermined level. This technique was very effective and prevented the distance measurement data from being significantly shifted.

[0007]

However, in the above-mentioned conventional example, since the distance data in the unstable region is ignored, there are the following problems.

1) The distance measuring ability is deteriorated (distance measurement of a low reflectance subject or a long distance subject cannot be performed).

2) The accuracy of distance measurement is not improved (because changes in distance measurement data due to the magnitude of reflected light cannot be absorbed).

3) The distance measuring range is narrow (in order to ignore the data in the unstable area).

(Object of the Invention) It is an object of the present invention to provide a distance measuring device which can prevent the distance measurement from becoming impossible and reduce the accuracy, and can widen the distance measuring range.

[0012]

According to the present invention, there is provided correction means for correcting the distance information obtained by the calculating means in accordance with the output from the discriminating means, and the distance information obtained by the calculating means is corrected. A correction means for correcting the distance measurement information and the output from the discrimination means is provided, and the calculation means calculates the magnitude of the received light signal, or the magnitude of the received light signal and the calculated distance information. I am trying to correct the distance information.

Further, according to the present invention, the power supply voltage fluctuation detecting means for detecting fluctuations in the power supply voltage, and the correction means for correcting the distance information obtained by the calculating means according to the output from the power supply voltage fluctuation detecting means. Power supply voltage changing means for detecting a change in the power supply voltage, and correction means for correcting the distance information obtained by the computing means according to the distance information and the output from the power supply voltage changing means. Is provided, and the distance information calculated by the calculation means is corrected according to the magnitude of the power supply voltage fluctuation or the magnitude of the power supply voltage fluctuation and the calculated distance information.

Further, according to the present invention, the drive current detecting means for detecting the drive current of the light projecting means and the correcting means for correcting the distance information obtained by the calculating means according to the output from the drive current detecting means. Is provided, and the drive current detection means for detecting the drive current of the light projecting means and the distance information obtained by the calculation means are corrected in accordance with the distance information and the output from the drive current detection means. And a correction means,
The distance information calculated by the calculation means is corrected according to the magnitude of the drive current of the light projecting means or the magnitude of the drive current of the light projecting means and the calculated distance information.

[0015]

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 a schematic structure of a distance measuring device according to a 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), 3 is a projection drive circuit for lighting the iRED 1, 2 is a semiconductor position detector (hereinafter referred to as PSD), which is a light receiving means for receiving reflected light from a subject, 4 is from the PSD 2 Is a light-receiving circuit that converts the current of to a voltage and amplifies it. Reference numeral 5 is a signal level detector for detecting the magnitude of the light receiving signal of the PSD 2 input through the light receiving circuit 3, and 6 is the PSD 2 input through the light receiving circuit 3.
2 is a distance measurement calculation circuit that calculates distance information based on the received light signal in. Reference numeral 7 is a microcomputer for controlling these.

FIG. 2 is a diagram showing the relationship between the magnitude of the received light signal and the distance (distance measurement data before correction) when the distance is measured by the distance measuring device constructed in FIG.

As shown in this figure, even for objects at the same distance, an error occurs in the received light signal until the received light signal reaches a certain magnitude (the portion indicated by the broken line represents the ideal signal magnitude). ), This tendency becomes more remarkable as the distance increases.

In the above-mentioned Japanese Utility Model Laid-Open No. 55-79320, an infinite distance is uniquely set when the level is lower than a predetermined level that causes an error (lower than the light receiving level described as AF infinity determination in FIG. 2). However, it had the problems as described above.

Therefore, in the first embodiment of the present invention, the distance information is corrected using the magnitude of the received light signal to obtain the final distance data. The operation for realizing this will be described with reference to the flowchart of FIG.

First, in step 101, the iRED 1 is driven through the light projecting drive circuit 3 to project light toward a subject. Then, the next step 102 and step 103
In the above, the reflected light from the subject is received in a state in which the signal of PSD2, which is the sensor, can be captured. Next step 1
In 04, the ratio of the signals output from both ends of the PSD 2 is calculated by a predetermined calculation to calculate the calculation data.

Next, in steps 105 to 107, correction calculation is performed as necessary. First, in step 105, the intensity of the received light signal is determined to determine whether correction is necessary (this execution In the example, it is determined whether it is 100 mV or less). As a result, if necessary (when the signal is weak), the process proceeds to step 106, where, for example, the following calculation is performed,
Calculate distance data.

The distance data = (operation data) - (correction value) = (operation data) - (100 receiving output) and by applying a correction to the ^2/10 or more as to determine the distance data.

On the other hand, if the received light signal is strong, step 10
In step 7, the calculation data is used as the distance data without correction, and the distance measuring operation is completed.

As described above, in the first embodiment, the magnitude of the received light signal is checked, and if it is lower than the predetermined level, the distance data is corrected. Can be prevented.

(Second Embodiment) FIG. 4 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. The circuit configuration is shown in FIG.
The description is omitted because it is the same as the above, and the same parts as those in the operation of FIG.

First, in step 201, the iRED 1 is driven through the light projecting drive circuit 3 to project light toward a subject. Then, the next step 202 and step 203
In the above, the reflected light from the subject is received in a state in which the signal of PSD2, which is the sensor, can be captured. Next step 2
In 04, the ratio of the signals output from both ends of the PSD 2 is calculated by a predetermined calculation to calculate the calculation data.

Next, in steps 205 to 210, correction calculation is performed as necessary. First, in step 2 and 5, the strength of the received light signal is determined to determine whether or not the correction is necessary. As a result, if necessary, the process proceeds to step 208, and it is determined whether or not the result of the operation data is far or close to 1 m (because the correction amount differs depending on the distance). Calculate the distance data.

The distance data = (operation data) - (correction value) = (operation data) - (100 receiving output) and by applying a correction to the ^2/10 or more as to determine the distance data.

Also, when the distance is closer than 1 m, the process proceeds to step 210 to perform the same calculation, and the following calculation is performed to calculate the distance data.

The distance data = (operation data) - (correction value) = (operation data) - (100 receiving output) and by applying a correction to the ^2/8 or more as to determine the distance data.

On the other hand, if the received light signal is strong, step 20
In step 7, the calculation data is used as the distance data without correction, and the distance measuring operation is completed.

As described above, in the second embodiment, the calculation data is corrected by the raw data of the size and distance of the received light signal, so that the accuracy of distance measurement can be prevented from lowering.

(Third Embodiment) FIG. 5 is a flow chart showing the operation of the distance measuring apparatus in the third embodiment of the present invention, and FIG. 6 is a correction data table used in this embodiment. Hereinafter, description will be given according to the flowchart of FIG. The circuit configuration is the same as that in FIG. 1 and is therefore omitted, and the same parts as those in FIG. 3 have the same numbers from the tenth digit of the step number. The correction data table of FIG. 6 is stored in the ROM of the microcomputer 7.

First, in step 301, the iRED 1 is driven through the light projecting drive circuit 3 to project light toward a subject. Then, the next step 302 and step 30
In 3, the sensor 2 receives the signal of the PSD 2 and receives the reflected light from the subject. In the next step 304, the ratio of the signals output from both ends of the PSD 2 is calculated by a predetermined calculation to calculate the calculation data.

In the next step 311, it is determined whether or not the magnitude of the received light signal is 100 mV or more, and if so, the process proceeds to step 317, and the distance measurement is ended using the calculation data as the distance data.

If the received light signal is less than 100 mV, the process proceeds from step 311 to step 312, where it is determined whether the received light signal is 50 mV or more. If the received light signal is 50 mV or more, the process proceeds to step 313, and the distance measurement is ended by using the data obtained by adding one pulse (the correction value corresponding to one pulse is predetermined) to the calculation data as the distance data. If it is less than 50 mV, the process proceeds from step 314 to step 314, where it is determined whether it is 20 mV or more. As a result, if the voltage is 20 mV or more, the process proceeds to step 315, and the data obtained by adding 3 pulses to the calculation data is used as the distance data to complete the distance measurement. Also, the output of the received light signal is 20 mV
If less, go from step 314 to step 316,
The distance measurement is completed by using the data obtained by adding 5 pulses to the calculated data as the distance data.

As described above, in the third embodiment, by having the correction data table according to the output of the received light signal, it is possible to make a finer correction, thereby preventing the deterioration of the ranging accuracy. You can

(Fourth Embodiment) FIG. 7 is a flow chart showing the operation of the distance measuring apparatus in the fourth embodiment of the present invention, and FIG. 8 is a correction data table used in this. Hereinafter, a description will be given according to the flowchart of FIG. The circuit configuration is the same as that in FIG. 1 and is therefore omitted, and the same parts as those in FIG. 3 have the same numbers from the tenth digit of the step number. The correction data table of FIG. 8 is stored in the ROM of the microcomputer 7.

First, in step 401, the iRED1 is driven through the light projecting drive circuit 3 to project light toward a subject. Then, the next step 402 and step 403
In the above, the reflected light from the subject is received in a state in which the signal of PSD2, which is the sensor, can be captured. Next step 4
In 04, the ratio of the signals output from both ends of the PSD 2 is calculated by a predetermined calculation to calculate the calculation data.

In the next step 421, it is determined whether or not the operation data is 1 m or more, and if it is 1 m or more, the process proceeds to step 422, in which it is determined whether or not the light reception signal output is 30 mV or more. If it is 30 mV or more, the process proceeds to step 426, and the data obtained by adding one pulse to the calculation data is used as the distance data to complete the distance measurement. If the light reception signal output is less than 30 mV, the process proceeds to step 427,
The distance measurement is ended by using the data obtained by adding 3 pulses to the calculation data as distance data.

If the calculated data is less than 1 m in step 421, the process proceeds to step 423, where it is determined whether the output of the light receiving signal is 30 mV or more. Then, if it is 30 mV or more, the process proceeds to step 428, and the distance measurement is ended by using the data obtained by adding 3 pulses to the operation data. If it is less than 30 mV, step 42
The process proceeds to step 9 and the distance measurement is completed by using the data obtained by adding 6 pulses to the calculation data as distance data.

As described above, in the fourth embodiment, since the correction data provided on the basis of the distance and the magnitude of the received light output is used, it is possible to perform finer correction to thereby measure the distance. It is possible to prevent a decrease in accuracy.

(Fifth Embodiment) FIG. 9 is a block diagram showing the schematic arrangement of a distance measuring apparatus according to the fifth embodiment of the present invention. In FIG. 9, 11 is an iRED, 1 is a light projecting means.
3 is a light projecting drive circuit for lighting the iRED 11;
Is a PSD which is a light receiving means for receiving the reflected light from the object, 14 is a light receiving circuit for converting the current from the PSD 12 into a voltage and amplifying it, and 15 is a light receiving signal at the PSD 12 input through the light receiving circuit 13. A signal level detector for detecting the magnitude, and 16 for inputting P through the light receiving circuit 13.
A distance measurement calculation circuit for calculating distance information based on a light reception signal in SD12, a non-volatile memory (hereinafter referred to as an EEPROM) 18 for storing distance correction data, and a microcomputer 17 for controlling these.

In this embodiment, the distance correction data is not stored in the microcomputer 17, but an external EEPROM is used.
18 is stored. As a result, it becomes possible to easily correct the correction data as necessary even after the device is assembled.

(Sixth Embodiment) FIG. 10 is a block diagram showing the schematic arrangement of a distance measuring apparatus according to the sixth embodiment of the present invention. In the figure, reference numeral 21 denotes an iRED which is a light projecting means,
23 is a light projecting drive circuit for lighting the iRED 21;
2 is a PSD which is a light receiving means for receiving the reflected light from the object, 24 is a light receiving circuit for converting the current from the PSD 22 into a voltage and amplifying it, 25 is a light receiving signal at the PSD 22 input through the light receiving circuit 23 , 26 is a signal level detector for detecting the magnitude of the distance, 26 is a distance measuring calculation circuit for calculating distance information based on a light receiving signal in the PSD 22 input through the light receiving circuit 23, and 28 is an EE for storing distance correction data.
PROM and 27 are microcomputers for controlling these. Two
Reference numeral 9 denotes a distance input device for inputting distance information from the outside. For example, when the subject is located at a distance of 1 m, 1
A signal corresponding to m is input to the microcomputer 27.

FIG. 11 is a flow chart showing the operation of the distance measuring device having the above-mentioned structure, which will be described below. Note that the same parts as the operation in FIG.
Numbers below the 0th digit are the same.

First, in step 501, the iRED 21 is driven via the light projecting drive circuit 23 to project light toward the subject. Then, the next step 502 and step 5
At 03, the reflected light from the subject is received in a state in which the signal of the PSD 22 which is the sensor can be captured. In the next step 504, the ratio of the signals output from both ends of the PSD 52 is calculated by a predetermined calculation, and the calculation data is calculated.

At the next step 531, it is judged whether or not the distance information is inputted from the outside through the distance input device 29, and if not, the routine proceeds to step 532, for example as in the first embodiment. Then, the calculation data is corrected to correct the distance measurement operation.

On the other hand, if the distance is input in step 531, the process proceeds to step 533, the correction amount is calculated by the difference between the calculation data and the input data, and the correction amount is calculated in step 533 in the next step 534. The corrected amount is rewritten as EEPROM data, and the distance measurement is completed.

As described above, in the sixth embodiment, the distance measuring data correcting means is provided in the camera itself, so that the distance measuring accuracy of each object is improved and the distance measuring accuracy of various objects is improved. The decrease can be prevented.

In the above-described first to sixth embodiments, the magnitude of the signal received by the light receiving means is detected, and the magnitude of the signal or the data obtained by the operation is also taken into consideration to calculate the operation data. Since the correction is added to, it is possible to cope with the response delay on the circuit, the level change, etc., and it is possible to measure the distance in the area where the signal light is small. Therefore, it becomes possible to prevent the distance measurement from becoming impossible and to reduce the accuracy, and it is possible to widen the distance measurement range.

(Seventh Embodiment) FIG. 12 is a block diagram showing the schematic arrangement of a distance measuring apparatus according to the seventh embodiment of the present invention. In the figure, reference numeral 51 denotes infrared light emission which is a light projecting means. A diode, 53 is a light projecting drive circuit for lighting the iRED 51, 52 is a PSD which is a light receiving means for receiving the reflected light from the subject, 54 is a light receiving circuit for converting the light receiving current from the PSD 52 into a voltage and amplifying it. Reference numeral 56 is a signal level detection circuit for detecting the magnitude of the received light signal from the PSD 52 via the light receiving circuit 53, and if it is higher than a certain level, it is output to a current setting circuit 55 described later, and 55 is an iR.
A current setting circuit that controls the current value flowing to the ED 51 by a signal level detection signal or the like, and 57 is a microcomputer that calculates the distance to the subject by a signal from the light receiving circuit 54 and controls these. Reference numeral 59 is a camera power supply, and 58 is a power supply voltage fluctuation detection circuit for detecting a power supply voltage fluctuation.

FIG. 13 is a diagram showing the relationship between the power supply voltage fluctuation and the distance when the distance is measured by the distance measuring device constructed in FIG. 12, and the horizontal axis is based on the signal from the light receiving circuit 53. It is the calculated distance data, and the vertical axis represents the fluctuation range of the power supply voltage or the magnitude of the projected current. When the fluctuation of the power supply voltage or the magnitude of the projected current becomes large, it is indicated by a curve as illustrated. Error occurs (the line indicated by the broken line is ideal).

Therefore, the operation in the seventh embodiment of the present invention for correcting the distance information by using the magnitude of the fluctuation of the power supply voltage and obtaining the final distance data will be described with reference to the flowchart of FIG. To do.

First, in step 600, iRED
51 is projected toward the subject, and in the next step 601, the reflected light is captured by the PSD 52. And
In the next step 602, the ratio of the signals output from both ends of the PSD 52 is calculated by a predetermined calculation to calculate the calculation data. Then in step 603,
The calculation data obtained in step 602 is corrected by calculation according to the fluctuation of the power supply voltage, the distance data is determined, and the distance measuring operation is ended.

As described above, in the seventh embodiment, since the distance measurement data is calculated by performing the correction according to the magnitude of the fluctuation of the power supply voltage, the reduction of the distance measurement accuracy is prevented. You can do it.

(Eighth Embodiment) FIG. 15 is a flow chart showing the operation of the distance measuring apparatus in the eighth embodiment of the present invention, which will be described below. Since the circuit configuration is the same as that of FIG. 12, the description thereof is omitted, and the same parts as those of the operation of FIG.

First, in step 700, iRED
51 is projected toward the subject, and in the next step 701, the reflected light is captured by the PSD 52. And
In the next step 702, the ratio of signals output from both ends of the PSD 52 is calculated by a predetermined calculation to calculate the calculation data. Then in step 704,
The calculation data is corrected according to the calculation data obtained in step 702 and the fluctuation of the power supply voltage, the distance data is determined, and the distance measuring operation is ended.

As described above, in the eighth embodiment, the final distance measuring data is calculated by performing the correction by the calculation according to the magnitude of the fluctuation of the power supply voltage and the calculated distance data. It is possible to prevent a decrease in distance measurement accuracy.

(Ninth Embodiment) FIG. 16 is a flow chart showing the operation of the distance measuring apparatus in the ninth embodiment of the present invention, which will be described below. The circuit configuration is the same as that in FIG.

In this embodiment, the magnitude of the electric current of the iRED 51 is used instead of the magnitude of the fluctuation of the power supply voltage to correct the distance information to obtain the final distance data.

First, in step 801, iRED
Set the MAX current of 51. And step 802
In, the iRED 51 is actually turned on, and in the next step 803, the current counter of the iRED 51 is set to zero.

Next, in step 804, PSD5
The level of the received light signal from 2 is detected and the set level (10
0 mV), and if it is above the set level, step 8
Move to 05 and enter the current control of iRED51 here. That is, the number of levels of the iRED current dropped from the MAX current value is counted. Then, the next step 806
In step 1, a new current value of iRED 51 is set (for example, -30 mA), the process returns to step 804, and while the light receiving output is at or above the set level, this step 804 → 8.
The operation of 05 → 806 is repeated.

After that, when the light receiving output of the PSD 52 is smaller than the set level, the step 80 is followed by the step 80.
7, the output of PSD 52 is fetched, and step 808
At, the ratio of signals from both ends of the PSD 52 is calculated by a predetermined calculation to calculate the calculation data. And
In step 809, the calculation data obtained by the calculation is corrected according to the magnitude of the current of the iRED 51, the final distance data is determined, and the distance measuring operation is ended.

Thus, in this ninth embodiment, the iRE
Since the calculation data is corrected in accordance with the magnitude of the current of D51, it is possible to prevent the distance measurement accuracy from decreasing.

(Tenth Embodiment) FIG. 17 shows the first embodiment of the present invention.
It is a flow chart which shows operation of the range finder in the example of 0, and is explained according to this below. Since the circuit configuration is the same as that of FIG. 12, the description thereof is omitted, and the same parts as those of the operation of FIG.

First, in step 901, iRED
Set the MAX current of 51. And step 902
In, the iRED 51 is actually turned on, and in the next step 903, the current counter of the iRED 51 is set to zero.

Next, in step 904, PSD5
The level of the received light signal from 2 is detected and the set level (10
0 mV), and if it is above the set level, step 9
Move to 05 and enter the current control of iRED51 here. That is, the number of levels of the iRED current dropped from the MAX current value is counted. Then, the next step 906
In step 1, a new current value of iRED 51 is set (for example, -30 mA), the process returns to step 904 again, and while the light receiving output is at or above the set level, this step 904 → 9.
The operation of 05 → 906 is repeated.

Thereafter, when the light receiving output of the PSD 52 is smaller than the set level, the steps 90 to 90 are executed.
7, the output of PSD 52 is fetched, and step 908
At, the ratio of signals from both ends of the PSD 52 is calculated by a predetermined calculation to calculate the calculation data. And
In step 910, the calculation data is corrected according to the calculation data obtained by the calculation and the magnitude of the current of the iRED 51, and the distance measuring operation is ended.

Thus, in the tenth embodiment, iR
Since the correction is performed by the calculation based on the magnitude of the current of the ED 51 and the raw distance data to calculate the final distance measurement data, it is possible to prevent the distance measurement accuracy from deteriorating.

(Eleventh Embodiment) FIG. 18 shows the first embodiment of the present invention.
20 is a flowchart showing the operation of the distance measuring device in the first embodiment, and FIG. 19 is a correction data table used in this embodiment. Hereinafter, a description will be given according to the flowchart of FIG. Since the circuit configuration is the same as that of FIG. 12, the description thereof is omitted, and the same parts as those of the operation of FIG. In addition, FIG.
The correction data table of is stored in the ROM of the microcomputer 57.

First, in steps 1101 and 1102, the iRED 51 for measuring the distance is driven, and the light is projected toward the subject. Then, in order to make the current of iRED appropriate depending on the magnitude of the reflected light, the steps 1104 to
Adjust at 1106. This determines the iR
It is projected toward the subject by the ED current.

In the next step 1107, the PSD
52, and in the next step 1108,
The ratio of the signals output from both ends of the PSD 52 is calculated by a predetermined calculation, and the calculation data is calculated. Then, in the next step 1111, it is determined whether or not the magnitude of the current of the iRED 51 is a predetermined value (540 mA = 600−30 × 2) or more, and if it is the predetermined value or more, the process proceeds to step 1115, where the calculation data is calculated. The distance measurement is completed with the value obtained by adding the correction pulse 5 to the distance data.

If it is less than the predetermined value (540 mA) in step 1111, the process proceeds to step 1112,
Here, the magnitude of the current of the iRED 51 is a predetermined value (420 m
It is determined whether or not A = 600−30 × 6) or more. As a result, if it is 420 mA or more, the process proceeds to step 1116,
Here, the value obtained by adding the correction pulse 3 to the calculation data is used as the distance data, and the distance measurement is ended.

In step 112, 420
If less than mA, proceed to step 1113, this time iR
The magnitude of the current of the ED 51 is a predetermined value (240 mA = 600
-30 × 12) or more is determined. If 240m
If A or more, the process proceeds to step 1117, and the value obtained by adding the correction pulse 1 to the calculation data is used as the distance data, and the distance measurement is ended.

In step 1113, the iRE
If the magnitude of the current of D51 is less than 240 mA, the process proceeds to step 1114, and the distance measurement is ended by using the calculation data as the distance data.

Thus, in this eleventh embodiment, iR
By having a correction data table according to the magnitude of the current of the ED 51, it is possible to perform finer correction and prevent a decrease in distance measurement accuracy.

It goes without saying that this method can be similarly applied to the above-described method of correcting the magnitude of the power supply voltage.

(Twelfth Embodiment) FIG. 20 shows the first embodiment of the present invention.
22 is a flowchart showing the operation of the distance measuring device in the second embodiment, and FIG. 21 is a correction data table used in this embodiment. Hereinafter, a description will be given according to the flowchart of FIG. Since the circuit configuration is the same as that of FIG. 12, the description thereof is omitted, and the same parts as those of the operation of FIG. In addition, FIG.
The correction data table of is stored in the ROM of the microcomputer 57.

First, in steps 1201 and 1202, the iRED 51 for measuring the distance is driven, and the light is projected toward the subject. Then, in order to make the current of iRED appropriate according to the magnitude of the reflected light, steps 1204 to
Adjust at 1206. This determines the iR
It is projected toward the subject by the ED current.

In the next step 1207, the PSD
52, and in the next step 1208,
The ratio of the signals output from both ends of the PSD 52 is calculated by a predetermined calculation, and the calculation data is calculated. Then, in the next step 1221, a predetermined value (1
m) It is determined whether it is larger or smaller. If it is larger, the process proceeds to step 1222, and if it is smaller, the process proceeds to step 1225.

In step 1222, the iRE is further added.
It is determined whether the D current value is larger or smaller than a predetermined value (450 mA). If the D current value is larger, the process proceeds to step 1223, and the value obtained by adding the correction pulse 3 to the calculation data is set as the distance data, and the distance measurement is ended. If it is determined to be smaller in step 1222, the process proceeds to step 1224, and the value obtained by adding the correction pulse 1 to the calculation data is used as the distance data, and the distance measurement is ended.

When it is determined in step 1221 that the calculated data is smaller than the predetermined value (1 m), the process proceeds to step 1225, where the iRED current value (450 m
A) It is determined whether it is larger or smaller. If it is larger, the process proceeds to step 1226 and the value obtained by adding the correction pulse 6 to the calculation data is set as the distance data, and the distance measurement is ended. On the other hand, if it is determined in step 1225 that it is smaller, the process proceeds to step 1227, and the value obtained by adding the correction pulse 3 to the calculation data is set as the distance data, and the distance measurement is ended.

As described above, in the twelfth embodiment, the correction is made by using the correction data table composed of the operation data and the magnitude of the current of the iRED 51.
Fine correction is possible, and it is possible to prevent deterioration of distance measurement accuracy.

Needless to say, this method can be similarly applied to the above-described method of correcting the power supply voltage.

In the seventh to twelfth embodiments described above, the magnitude of the fluctuation of the power supply voltage or the magnitude of the current of iRED is detected, and this magnitude is used, or the operation data is further taken into consideration. Since the correction is added to the calculation data, it is possible to cope with the response delay and the level change on the circuit, and it is possible to measure the distance in a small area of the received light signal. That is,
It becomes possible to prevent the distance measurement from becoming impossible and to reduce the accuracy, and to widen the distance measurement range.

[0088]

As described above, according to the present invention,
Correcting means for correcting the distance information obtained by the calculating means in accordance with the output from the judging means is provided, and the distance information obtained by the calculating means is used as the distance measuring information and the output from the judging means. According to the present invention, the power supply voltage fluctuation detecting means for detecting fluctuations in the power supply voltage and the distance information obtained by the calculating means are supplied from the power supply voltage fluctuation detecting means. Is provided in accordance with the output of the power supply voltage fluctuation means for detecting fluctuations in the power supply voltage, and the distance information obtained by the computing means is output from the distance information and the power supply voltage fluctuation means. According to the present invention, the driving current detecting means for detecting the driving current of the light projecting means, and the distance information obtained by the computing means are used for the driving current detection. hand And a driving current detecting means for detecting the driving current of the light projecting means, and the distance information obtained by the calculating means, based on the distance information and the driving current detection means. And a correction means for correcting according to the output from the means, and according to the magnitude of the received light signal, or the magnitude of the received light signal and the calculated distance information, or the magnitude of the power supply voltage fluctuation or the power supply voltage fluctuation. The distance information calculated by the calculation means in accordance with the magnitude of the driving current of the light projecting means or the magnitude of the driving current of the light projecting means and the calculation distance information. I am trying to make corrections.

Accordingly, it becomes possible to prevent the distance measurement from becoming impossible and to prevent the accuracy from deteriorating, and to widen the distance measurement range.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a magnitude of a light receiving signal of the PSD of FIG. 1 and a distance.

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

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

FIG. 6 is a diagram showing a correction data table used in a third embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of the distance measuring device according to the fourth embodiment of the present invention.

FIG. 8 is a diagram showing a correction data table used in a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a distance measuring device according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a distance measuring device according to a sixth embodiment of the present invention.

FIG. 11 is a flowchart showing an operation of the distance measuring device according to the sixth embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a distance measuring device according to a seventh embodiment of the present invention.

FIG. 13 is a diagram showing the relationship between the magnitude of the iRED current of FIG. 12 or the magnitude of the power supply voltage fluctuation and the distance.

FIG. 14 is a flowchart showing an operation of the distance measuring device according to the seventh embodiment of the present invention.

FIG. 15 is a flowchart showing an operation of the distance measuring device according to the eighth embodiment of the present invention.

FIG. 16 is a flowchart showing an operation of the distance measuring device according to the ninth embodiment of the present invention.

FIG. 17 is a flowchart showing an operation of the distance measuring device according to the tenth embodiment of the present invention.

FIG. 18 is a flow chart showing the operation of the distance measuring device in the eleventh embodiment of the present invention.

FIG. 19 is a diagram showing a correction data table used in the eleventh embodiment of the present invention.

FIG. 20 is a flow chart showing the operation of the distance measuring apparatus in the twelfth embodiment of the present invention.

FIG. 21 is a diagram showing a correction data table used in a twelfth embodiment of the present invention.

[Explanation of symbols]

 1,11,21,51 iRED 2,12,22,52 PSD 5,15,25 Signal level detection circuit 6,16,26 Distance measurement calculation circuit 7,17,27,57 Microcomputer 18,28 EEPROM 55 Current setting circuit 58 Power supply voltage fluctuation detection circuit

Claims (18)

[Claims] 1. A light projecting means for projecting light toward an object to be measured,
A light receiving means for receiving the light reflected by the object to be measured, a determining means for determining the magnitude of a light receiving signal from the light receiving means,
In a distance measuring device including a calculation means for calculating distance information to a distance measurement target based on a light reception signal from the light receiving means, the distance information obtained by the calculation means is converted into A distance measuring device, characterized in that it is provided with a correcting means for making a correction. 2. A light projecting means for projecting light toward an object to be measured,
A light receiving means for receiving the light reflected by the object to be measured, a determining means for determining the magnitude of a light receiving signal from the light receiving means,
In a distance measuring device including a calculating means for calculating distance information to a distance measuring object based on a light receiving signal from the light receiving means, the distance information obtained by the calculating means is used as the distance measuring information and the determining means A distance measuring device, characterized in that a correction means for correcting the output according to the output from is provided. 3. A light projecting means for projecting light toward an object to be measured,
In a distance measuring device including a light receiving means for receiving light reflected by a distance measuring object and a calculating means for calculating distance information to the distance measuring object based on a light receiving signal from the light receiving means, A distance measuring device comprising: a power supply voltage fluctuation detecting means for detecting fluctuations; and a correcting means for correcting the distance information obtained by the computing means according to an output from the power supply voltage fluctuation detecting means. . 4. A light projecting means for projecting light toward an object to be measured,
In a distance measuring device including a light receiving means for receiving light reflected by a distance measuring object and a calculating means for calculating distance information to the distance measuring object based on a light receiving signal from the light receiving means, A power supply voltage changing means for detecting a change and a correction means for correcting the distance information obtained by the calculating means according to the distance information and the output from the power supply voltage changing means are provided. Ranging device. 5. A light projecting means for projecting light toward an object to be measured,
In the distance measuring device including a light receiving means for receiving the light reflected by the distance measuring object and a calculating means for calculating distance information to the distance measuring object based on a light receiving signal from the light receiving means, Drive current detection means for detecting the drive current of the means,
A distance measuring device comprising: a correction unit that corrects the distance information obtained by the calculation unit according to an output from the drive current detection unit. 6. A light projecting means for projecting light toward an object to be measured,
In the distance measuring device including a light receiving means for receiving the light reflected by the distance measuring object and a calculating means for calculating distance information to the distance measuring object based on a light receiving signal from the light receiving means, Drive current detection means for detecting the drive current of the means,
A distance measuring device comprising: a correction unit that corrects the distance information obtained by the calculation unit according to the distance information and the output from the drive current detection unit. 7. The distance measuring apparatus according to claim 1, wherein the correcting means is means for correcting the distance information obtained by the calculating means by calculation according to the output from the determining means. 8. The correcting means is means for correcting the distance information obtained by the calculating means according to an output from the judging means by referring to a predetermined correction data table. The distance measuring device according to claim 1. 9. The measuring device according to claim 2, wherein the correcting device is a device that corrects the distance information obtained by the calculating device according to the distance information and the output from the determining device. Distance device. 10. The correcting means is means for correcting the distance information obtained by the calculating means according to the distance information and the output from the judging means by referring to a predetermined correction data table. The distance measuring device according to claim 2, wherein 11. The distance measuring device according to claim 3, wherein the correction means is means for correcting the distance information obtained by the calculation means by calculation according to the output from the power supply voltage fluctuation detection means. . 12. The correcting means is means for correcting the distance information obtained by the calculating means according to an output from the power supply voltage fluctuation detecting means by referring to a predetermined correction data table. The distance measuring device according to claim 3, which is characterized in that. 13. The correcting means is means for correcting the distance information obtained by the calculating means by calculation according to the distance information and the output from the power supply voltage fluctuation detecting means. The described distance measuring device. 14. The correcting means corrects the distance information obtained by the calculating means according to the distance information and the output from the power supply voltage fluctuation detecting means by referring to a predetermined correction data table. The distance measuring device according to claim 4, which is a means. 15. The distance measuring device according to claim 5, wherein the correcting means is means for correcting the distance information obtained by the calculating means by calculation according to the output from the drive current detecting means. 16. The correcting means is means for correcting the distance information obtained by the calculating means in accordance with an output from the drive current detecting means by referring to a predetermined correction data table. The distance measuring device according to claim 5. 17. The correction means is a means for correcting the distance information obtained by the calculation means by calculation according to the distance information and the output from the drive current detection means. Ranging device. 18. The correcting means corrects the distance information obtained by the calculating means according to the distance information and the output from the drive current detecting means by referring to a predetermined correction data table. 7. The distance measuring device according to claim 6, wherein