JPH11183618A - Method for improving laser range finding capability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve range-finding accuracy by obtaining distance from a range-finding time difference using a constant current linear charging circuit, converting the data of two target distance signals and obtaining an average value, and obtaining a correction level and a correction gain for correction data. SOLUTION: A laser beam emission part 10 emits laser beams from a laser diode LD at an accurate time using a high voltage from a high-voltage supply part 30 and a trigger signal from a central-processing unit 60. A laser beam reception part 20 receives a biased voltage of a detector PAD from the high-voltage supply part 30, receives laser beams being reflected by a target and amplifies them, and adjust them to the best sensitivity. A precision charging part 40 converts the time difference between emission and reception of pulses to a pulse width by an internal R/S FF and converts it to a voltage ratio in a linear capacitor charging circuit. A self calibration circuit 50 is a two-point self calibration circuit and compensates for the changes in a current source and an electrical capacitance caused by the temperature by utilizing a two-point calibration charging line. An A/D converter 70 A/D converts a voltage value obtained by the precision charging part 40 and the result to the central-processing unit 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the laser distance measuring ability, and more particularly, to stabilizing the measurement of a laser distance meter under the premise that laser light emitting efficiency does not need to be improved. The present invention relates to a method that has a self-calibration function and reduces the effects of temperature effects to increase accuracy.

[0002]

2. Description of the Related Art The operation of a laser as a distance meter has already been successfully developed.
rTech) company filed U.S. Pat. No. 5,359,404, also 5,612,779.
No. 5,574,552 has high accuracy (error 1
m), a one kilometer laser distance meter using a laser light emitting diode as a light source is listed. The technologies used in it are as follows. (1) By using the method of rapid charge and slow discharge,
Achieve the function of time amplification. In this way, the time from the emission of light by the laser diode to the reception of the round wave by the receiving circuit is amplified (about 6.6 μS) and amplified by a factor of about 100, during which time a sample is taken with a low-speed clock. , And convert it to the survey distance. However, under the premise of rapid charging and low-speed discharging, a high-precision current source must be used in the manufacture of electric circuits, and although the accuracy has been increased to an error of 1 m, the parts Such costs have increased. (2) The sensitivity of the receiving circuit is optimized by using a threshold automatic adjustment technique. However, the sensitivity became too high, making control difficult.

In addition, known laser rangefinders do not take into account changes in the surrounding environment, that is, the shift phenomenon formed by temperature effects affects the accuracy and stability of distance measurements. Was not taken into account.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for optimizing the sensitivity of a laser range finder by means different from those known in the art. The need for high accuracy can be achieved with only small adjustments to the threshold voltage. According to the method of the present invention, the accuracy of the distance measurement of the laser range finder can be made within an error range of 1 m, and the laser range finder according to the present invention particularly has functions of self-calibration and temperature compensation.

[0005]

According to the first aspect of the present invention, there are provided the following two methods (1) and (2), namely, (1) a constant current linear charging method, and a time difference of laser beam ranging. Is converted into a voltage value, the voltage value is converted into a digital signal, and distance data is obtained through calculation in a central processing unit (2).
Using self-calibration and temperature compensation technology, two target distance signals are simulated and sent to a constant current linear charging circuit to be converted into two data, and the central processing unit calculates the average to obtain the correction level and correction gain. And give it to the central processing unit.
Immediate data correction to ensure the accuracy of surveying and the effect of temperature compensation.The above two methods are included, and the time difference between laser light emission and reception is effectively converted to the number of distances, and the temperature effect is corrected. The laser distance measurement ability is characterized by eliminating the effect of the shift phenomenon caused by the deviation on the accuracy and stability of the distance measurement, greatly improving the distance measurement ability, and increasing the accuracy of the distance measurement. How to improve.

According to a second aspect of the present invention, there is provided a method for improving a laser distance measuring capability according to the first aspect, wherein:
In the method (1), the start pulse and the end signal are converted into a negative pulse having one equivalent pulse width by using a flip-flop, and active linear charging is performed in one capacitor within the time of the negative pulse width. And converting the voltage value into a digital signal by one analog-to-digital converter, sending the digital signal to a central processing unit, and acquiring a measured distance value.

According to a third aspect of the present invention, the flip-flop has an R
The method for improving the laser distance measuring ability according to claim 2, wherein an S flip-flop is adopted.

According to a fourth aspect of the present invention, there is provided a method for improving the laser distance measuring capability according to the second aspect, wherein a 10-bit analog-to-digital converter is employed as the analog-to-digital converter.

According to a fifth aspect of the present invention, there is provided a method for improving a laser distance measuring capability according to the first aspect, wherein:
In the method (2), the two-point correction method is used to correct and compensate for the change in the current source and the capacitance value formed by the temperature, to obtain the correction gain and the correction level from the two-point data, and to immediately obtain the sample. It is a method to improve the laser distance measurement ability, which is characterized by obtaining the correct value after correction by combining the value and the correction formula.

According to a sixth aspect of the present invention, in the method for improving the laser distance measuring ability according to the first aspect, when the central processing unit immediately sends correction pulses of two known pulse widths after the system is started, each of them is output. Integrating to obtain an integrated voltage value, forming a single survey response curve from these integrated voltage values, and further modifying the survey response obtained using the two original standard values to obtain an ideal response, and a central processing unit After calculating the correction gain and correction level, enter the normal operation process, control the voltage, fire, sample, average the effective value, get the immediate sample value, and finally use further correction formula Then, the correction is performed to obtain a numerical value of the same accuracy, and thus the accuracy of the distance measurement is improved, thereby improving the laser distance measuring ability.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric circuit technology for achieving the calibration and temperature compensation functions in the method for improving the laser distance measuring capability of the present invention includes the following three electric circuits. 1. It is a constant current linear charging circuit, converts the time difference of laser distance measurement into voltage, further converts it into digital data using an analog-to-digital converter, calculates the data in the central processing unit, and displays the distance data on the display unit What is used to do. 2. It is a calibration circuit, two simulated target distance signals are sent to a constant current linear charging circuit, converted into two data, an average value is obtained by a central processing unit, a correction level and a correction gain are obtained, and given to the central processing unit, Used to make immediate data corrections to ensure survey accuracy and temperature compensation. 3. The laser emitting and receiving part of the present invention is provided with three kinds of noise reduction techniques (this part has already been filed as a separate patent), so that the receiving part has the best signal-to-noise ratio (S / N) and the best. To gain sensitivity.

[0012]

FIG. 1 is a block diagram of an electric circuit according to the present invention.
As shown in the figure, the laser range finder of the present invention includes a laser beam emitting portion 10 (Laser Transmit).
Section), laser beam receiving portion 20 (Lase)
r Receive Section, high voltage supply section 30 (HV Power Supply), precision charging section 40 (Precision Charge Sect)
ion), self-calibration circuit 50 (Self Calibr
attor), a central processing unit 60 (CPU) and an analog-to-digital converter 70 (A / D). A detailed description of them is as follows.

The laser beam emitting section 10 described above is provided with the necessary high pressure provided by the high pressure supply section 30 and the central processing unit 60.
Receives the trigger signal provided by the laser diode, and causes the laser diode LD to emit laser light at an accurate time.

The aforementioned laser light receiving section 20 receives the required detector PAD pressure provided by the high pressure supply section 30, receives and amplifies the laser light that has returned on the target, and adjusts it with the highest working sensitivity. I do.

The above-described precision charging section 40 converts the time difference between pulse emission and pulse reception into a pulse width by an internal R / S flip-flop (FIG. 4), and further converts this pulse width by a linear capacitor charging circuit. Convert to voltage ratio.

The above-described self-calibration circuit 50 is one two-point self-calibration circuit, and uses a two-point calibration charging straight line and a current source formed by temperature under the principle of making two points straight. Compensate for capacitance changes.

The central processing unit 60 provides the timing signals required by each of the units.

The aforementioned analog / digital converter 70
(A / D) (in this embodiment, a 10-bit analog-to-digital converter is used)
The voltage value obtained at 0 is converted to a digital signal and sent to the central processing unit 60 for further processing.

The point of the present invention lies in a method for improving the laser distance measuring capability. For this reason, the entire circuit is described only in the laser light emitting part 1 in the manual.
0, only the laser light receiving section 20, the high voltage supply section 30, and the central processing unit 60 will be described, and how to increase the precision and stability of laser distance measurement will be described below.

FIG. 2 shows an electric circuit of the laser light emitting portion 10 of the present invention. The components of this circuit are very few, so that the present invention allows these components to be placed in one very small box of anti-electromagnetic wave (EMWAVE) interference. As shown, the capacitors C1, C2, C4, C5 and the resistor R1 form a π-type filter to eliminate interference in the high voltage supply 30. The resistor R2 and the capacitor C5 form one charging circuit, and the capacitor 5, the laser diode LD, the rapid diode D1, the load resistor R3 and the SCR form one discharging circuit, thereby generating pulsed laser light (FIG. 5). The laser firing time is determined by adding the positive end of one TTL signal to resistors R4 and R5.
And its timing is controlled by the central processing unit 60.

FIG. 3 is an electric circuit diagram of the laser light receiving portion of the present invention. The electric circuit of the laser light receiving portion 20 includes a logarithmic amplifier 21 (Log Amplifier),
Matching filter 22 (Matching filter)
er), the sunlight noise averaging circuit 23 (Sun-Noise)
Average Circuit), Rapid comparator 23
(High-Speed Comparator) and an optical band-pass filter 25 (Optical Ban).
d-Pass Filter).

The pressure deviation of the detector APD is determined by a capacitor C6,
The π-type filter composed of C7 and the resistor R6 eliminates the interference of the high voltage supply portion 30 and the coupling effect at the high voltage portions of the laser light emitting portion 10 and the laser light receiving portion 20.

The aforementioned optical bandpass filter 25 is tightly bonded in front of the detector APD and is used to filter most sunlight noise.

The load R7 is provided in series between the above-described electric resistance R6 and the detector, forms a logarithmic amplifier 21 with a capacitor C8, a resistance R8 and rapid diodes D2 and D3, and has a dynamic reception range in the laser light receiving portion 20. Which reduces the resulting gain when surveying short distances and increases the resulting gain when surveying long distances, forming a function similar to AGC.

The transistors Q1, Q2, and Q3 (in this embodiment, low-noise transistors are used) and a resistor R
9, R10, R11, R12, R13 compose a first variable resistance amplifier 221 which converts the laser light signal received by the detector APD into a voltage signal, as well as one band pass in cooperation with the aforementioned logarithmic amplifier 21. Form a filter,
At the same time, appropriate variables are selected to mutually match the frequency response of the bandpass filter with the frequency response of the laser light pulse to form one matching amplifier.

The second variable resistance amplifier 222 includes transistors Q4, Q5, Q6 and resistors R14, R15, R16, R
17, R18, R19, and C through a resistor R20.
9 couples to the collector of transistor Q3,
Another bandpass filter voltage amplifier is obtained,
In this way, the first variable resistance amplifier 221 and the second variable resistance amplifier 222 are added to the logarithmic amplifier 21 to form one matching filter 22, which generates a signal corresponding to the laser light pulse to obtain the best signal-to-noise ratio. It is made available.

An output terminal of the first variable resistance amplifier 221 is connected to an emitter follower (EmitterFollower).
Rectifier diode D4, capacitor C10, and voltage dividing resistors R21, R2
2, an average noise value of the first variable resistance amplifier 221 is obtained (this portion is referred to as a daylight noise averaging circuit 23), and this noise is output to the optical bandpass filter 25.
It is considered to be white noise where sunlight is generated inside. The coupling noise generated by the high voltage supply section 30 is automatically turned off by the voltage feedback circuit because the high voltage has already been established.

The threshold voltage of the rapid comparator 24 is adjusted by the output voltage of the average value of the daylight noise and the fixed threshold voltage formed by the resistors R23 and R24. When the daylight noise increases, the threshold voltage increases and the daylight noise increases. As the threshold voltage decreases, the threshold voltage also decreases.

The most important thing in a laser range finder is how to convert the time difference between the emission of a laser beam to a target and the reception of the laser beam bounced off the target into distance data. The technology adopted in the present invention is to convert the time difference into distance data effectively by utilizing the concept of precision charging.

As shown in FIG. 4, in the present invention, RS
Using the flip-flop 41, the start pulse (Sta)
rt Pulse) and an end signal (Stop Sign)
al) is converted into a minus pulse (output from Q) having an equivalent effective pulse width, and the opening and closing of the transistor Q8 is switched at high speed by the minus pulse, thereby changing the resistance R2
5, a constant current source composed of R26, R27, R28, operational amplifier OP, and transistor Q8 is obtained, and effective linear charging is performed in capacitor C11 within the time of the negative pulse width. Zener diode ZD and capacitor C12 terminate and hold the voltage at which charging is completed, and the analog-to-digital converter 70 converts this voltage to a digital signal and converts the voltage to a central processing unit 60.
Finally, the central processing unit 60 sends one high level to the resistors R29 and R30 and the transistor Q9 to turn on and ground the transistor Q9,
Clear the voltage stored in 12 and wait for the next survey and charge. The detailed timing of this part is shown in FIG.

Since temperature factors severely affect the accuracy of the precision charging section 40, the present invention allows for the correction of temperature-accurate accuracy through self-correction and calibration circuits and methods. In the present invention, a two-point correction method is adopted, and a two-point calibration charging straight line is used to compensate for a current source formed by temperature and a change in capacitance value based on the principle that two points are aligned. The correct value dcorr after the correction is obtained by obtaining a correction gain (Cal) using the formula shown in the following equation 1 with respect to the electric data of two points, and correcting using the formula shown in the equation 2 The level (Off) is obtained, and then the immediate sample value (dm) is further added to the formula shown in Equation 3.
Obtained by combining

(Equation 1)

(Equation 2)

(Equation 3)

The central processing unit 60 sends out correction pulses (Correction Pulses) of two known pulse widths, and furthermore, as shown at t1 in FIG.
Through the transistor Q10 at the AND gate, the resistors R25, R26, R27, R
28, R31, R32, an operational amplifier OP, and a current charging circuit composed of components including transistors Q7, Q8, to obtain an integrated voltage value dl '. Similarly, as shown at t2 in FIG. 7, one integrated voltage value d2 'is obtained with the correction pulse having the pulse width, and as shown in FIG. 8, the original standard values d1 and d2 are obtained. Of the survey responses obtained at d1 'and d2' (Measured
Response (Ideal)
Response (the correction formula is as described above), and after the central processing unit 60 calculates the correction gain (Cal) and the correction level (Off), the CPU enters the cleaning operation process, controls the power supply, fires, Sampling, averaging the effective values, obtaining an immediate sample value (dm), and finally modifying using a formula to obtain a numerical value of the same accuracy, thus an effective self-correction and temperature compensation circuit Can reduce the accuracy to less than 1 m.

As described above, the method for improving the laser distance measuring capability provided by the present invention provides a corresponding solution path for both the distance measuring capability and the accuracy of the distance measurement of the laser range finder. It is presented and provides an effective solution to the shortcomings and unachieved functions of known adjustment methods. Furthermore, it has a function not found in known methods, and has novelty, practicality, and industrial value.

[0034]

The features of the present invention are as follows. 1. The time difference between laser emission and reception is converted to a voltage magnitude, and the voltage magnitude is converted to a corresponding distance, which has the advantage of low efficiency consumption, and is powered by only one 9V battery. 2. Accuracy can be maintained within an error range of 0.5 m. 3. Output is 24W ~ 38W, pulse width 20ns ~ 50
ns semiconductor laser can be used to survey concrete building targets 1 km away.

The product made in accordance with the present invention is fairly sophisticated and can be used to measure the flight distance of a golf ball, and the receiver operates under best conditions to increase accuracy. The user can set a different number of firings for different targets, and the error of the distance value measured by firing at least twice at a certain fixed number of firings is less than 3 m, In the present invention, a more accurate distance can be measured by further averaging the distance values.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram of a laser distance meter of the present invention.

FIG. 2 is an electric circuit diagram of a laser beam emitting portion of the present invention.

FIG. 3 is an electric circuit diagram of a laser light receiving portion of the present invention.

FIG. 4 is an electric circuit diagram of a precision charging and self-calibration part of the present invention.

FIG. 5 is a timing chart of a precision charging portion.

FIG. 6 is a timing chart of the self-calibration part of the present invention.

FIG. 7 is a timing chart of the self-calibration part of the present invention.

FIG. 8 is a diagram showing a measured response curve and an ideal response curve in the self-calibration process of the present invention.

DESCRIPTION OF SYMBOLS 10 Laser light emitting part 20 Laser light receiving part 21 Logarithmic amplifier 22 Matching filter 221 First variable resistance amplifier 222 Second variable resistance amplifier 23 Sunlight noise averaging circuit 24 Rapid comparator 25 Optical bandpass filter 30 High voltage supply Part 31 pulse modulation IC 40 precision charging part 41 RS flip-flop 50 self-calibration circuit 60 central processing unit 70 analog / digital converter

Claims (6)

[Claims] 1. The following two methods (1) and (2) are used, that is, (1) a constant current linear charging method is used to convert a time difference of laser light ranging into a voltage value, and this voltage value is converted to a voltage value. Method of converting into a digital signal and acquiring distance data through calculation in a central processing unit (2) Using self-calibration and temperature compensation techniques, simulates two target distance signals and sends them to a constant current linear charging circuit to send two signals. Convert to data, calculate the average in the central processing unit, obtain the correction level and correction gain, give it to the central processing unit, correct the data immediately, and secure the accuracy of the survey and the temperature compensation effect. By using the above two methods, the time difference between the emission and reception of laser light is effectively converted to the number of distances, and the effect on the accuracy and stability of distance measurement caused by the shift phenomenon due to temperature effects is eliminated. Greatly improves the ability to measure distance A method for improving laser distance measurement capability, characterized by increasing the accuracy of distance measurement. 2. The method for improving the laser distance measuring ability according to claim 1, wherein the method (1) includes:
Using a flip-flop to convert the start pulse and end signal to a negative pulse of one equivalent pulse width, perform active linear charging in one capacitor within the time of the negative pulse width, and one analog digital A method for improving laser distance measuring capability, comprising converting the voltage value into a digital signal by a converter, sending the digital signal to a central processing unit, and acquiring a measured distance value. 3. The method of claim 2, wherein the flip-flop comprises an RS flip-flop. 4. The method according to claim 2, wherein a 10-bit analog-to-digital converter is used as the analog-to-digital converter. 5. The method for improving the laser distance measuring capability according to claim 1, wherein the method (2) includes:
Using the two-point correction method to correct and compensate for changes in the current source and capacitance formed by temperature, determine the correction gain and correction level from these two-point data, and combine them with immediate sample values and correction formulas. A method for improving the laser distance measuring ability, characterized in that an accurate value after correction is obtained in (1). 6. The method for improving laser distance measurement capability according to claim 1, wherein the central processing unit immediately sends correction pulses of two known pulse widths after system startup, and integrates each of them to integrate the integrated voltage. Obtain the values, form one survey response curve with these integrated voltage values, and further modify the survey response obtained using the two original standard values to make it an ideal response, and modify the gain and correction in the central processing unit. After calculating the level, enter the normal operation process, control the voltage, fire, sample, average the effective value, get the immediate sample value, and finally make further correction using the correction formula , Get numbers with the same precision,
A method for improving laser distance measuring ability, characterized by improving the accuracy of distance measurement in this way.