JP2006038652A - Distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance measuring device which can accurately measure a distance by avoiding the effects of electronic components characteristics due to temperature variation and power source fluctuation of electronic components constituting an electronic circuit. <P>SOLUTION: In measurement initiation state, a pulsing laser beam is emitted from a transmission means 2 and the emitted laser beam is split into an irradiation wave and a reference wave in a branching means 3, and irradiated to a measuring object 6. The reflection wave from the measuring object 6 and the reference wave are introduced into a wave reception means 4 and transmitted to a signal separation means 14. With the signal separation means 14, either of the reference wave signal or the reflection wave signal is passed to count with a counter 15, measure the period of each signal and obtain the distance to the measuring object from those time. When counting with the counter 15, the order of measurement of the reference wave signal and the reflection wave signal are replaced by turns like reference wave signal measurement, reflction wave signal measurement, reflection wave signal measurement, reference wave signal measurement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention irradiates a ranging object with a pulsed electromagnetic wave, measures the time taken to receive a reflected wave from the ranging object, and based on the measurement time, measures the distance to the ranging object. The present invention relates to a distance measuring device that measures

  Conventionally, by irradiating a measurement object with pulse laser light, detecting reflected light from the measurement object, and measuring the time from projecting the pulse laser light to receiving the reflected light, A distance measuring device for obtaining a distance is known.

  For example, a conventional distance measuring apparatus is configured as shown in FIG. A pulsed laser beam is emitted from the transmitter 61 toward the measurement object 69 by a drive signal from the drive circuit 67. The laser beam is branched by the beam splitter 60 into an irradiation wave toward the measurement object 69 and a reference wave toward the reception unit 62. The irradiation wave is applied to the target measurement object 69, and the reflected wave from the measurement object 69 is received by the receiving unit 62 and converted into an electrical signal. On the other hand, the reference wave is delayed by the delay unit 68, received by the receiving unit 62, and converted into an electric signal.

  The reflected wave signal and the reference wave signal converted into the electrical signal are amplified by the amplification unit 63, and then either the reflected wave signal or the reference wave signal is extracted by the mask unit 64, and the extracted signals are counted. The circuit unit 65 counts.

  Since either the reflected wave signal or the reference wave signal can be extracted by switching the mask state of the mask unit 64, the time required for counting a predetermined number of reflected wave signals by the counting circuit unit 65 The distance to the measurement object 69 is calculated by the processing unit 66 based on the difference from the time required for counting the predetermined number of reference wave signals by the counting circuit unit 65.

  Since the time required for light to pass through the distance measuring optical path is very short and errors are likely to occur, the reflected wave signal period and the reference wave signal period are accumulated in a certain amount and averaged as described above. Therefore, the accuracy of the measurement distance is increased by averaging the error.

JP 2001-124855 A Japanese Patent Laid-Open No. 3-264855

  However, in the above-described conventional technology, variation factors depending on component characteristics such as self-heating of electronic components used in the electronic circuit of the apparatus cannot be sufficiently removed, and the measurement value may vary.

  Normally, the processing time during measurement processing is very short, so it takes time to stabilize the internal state of the electronic components applied to the processing unit, or parts that react sensitively to power fluctuations are used. In this case, the accuracy of distance measurement is greatly affected. In particular, when an electrical delay means is used, a delay time fluctuation due to a temperature change has caused a large error in distance measurement.

  The present invention was devised to solve the above-mentioned problems, and is not affected by the characteristics of electronic components due to temperature changes or power supply fluctuations of the electronic components constituting the electronic circuit, so that accurate distance measurement is possible. It aims at providing the distance measuring device which can be performed.

  In order to achieve the above object, the invention described in claim 1 includes a wave transmitting means for periodically transmitting a pulsed electromagnetic wave, and a wave receiving means for receiving a reflected wave reflected by the measurement object. Branching means for branching a part of the transmitted electromagnetic wave and making it incident on the receiving means as a reference wave, and a signal received by the receiving means corresponding to a reflected signal component from a measurement object and a reference wave A signal separation unit that separates the reference signal component into a reference signal component, a reflection signal component separated by the signal separation unit or a reference signal component as a reference signal, gives a predetermined delay time, and transmits this signal as a drive signal to the transmission unit Delay means, first timing means for adding a predetermined number of cycles of the reflected signal component, second timing means for adding a predetermined number of cycles of the reference signal component, and the first timing means. Reflection Computation means for calculating the distance to the measurement object based on the difference between the addition cycle of the predetermined number of components and the addition cycle of the reference signal component for the predetermined number of times measured by the second timing means. When the first time measuring means and the second time measuring means are repeatedly used in succession, the measurement order by the first time measuring means and the second time measuring means is switched and repeatedly measured. It is a distance measuring device.

  The invention according to claim 2 is characterized in that the interval of the switching time between the measurement performed by the first timing unit and the measurement performed by the second timing unit is made constant. The distance measuring device according to claim 1.

  According to a third aspect of the present invention, the transmission means, the reception means, the signal separation means, the delay means, and the first time measurement means are started before the measurement operation processing for calculating the distance to the measurement object is started. The distance measuring device according to claim 1, wherein the pseudo-distance measuring operation is performed by driving the second timing means.

  According to a fourth aspect of the present invention, before starting the measurement operation process for calculating the distance to the measurement object, at least the signal is looped between the calculation unit and the delay unit. 3. The distance measuring device according to claim 1, wherein the delay means is driven.

  The invention according to claim 5 is the distance measuring device according to claim 4, wherein the arithmetic means controls the frequency so that the loop signal becomes a signal having a predetermined frequency.

  The invention according to claim 6 is provided with a temperature sensor installed to measure the temperature in the vicinity of the delay means, and controls the frequency of the loop signal in accordance with the temperature detected from the temperature sensor. The distance measuring device according to claim 5.

  The invention according to claim 7 is provided with a temperature sensor installed to measure the temperature in the vicinity of the delay means, and changes the number of loops of the loop signal according to the detected temperature from the temperature sensor. The distance measuring device according to claim 4.

  The invention according to claim 8 is provided with a temperature sensor installed to measure the temperature in the vicinity of the delay means, and according to the temperature detected from the temperature sensor, the wave transmitting means and the wave receiving means. 3. The supply voltage of the power supply means for supplying voltage to the signal separating means, delay means, first time measuring means, second time measuring means, and arithmetic means is controlled. It is a distance measuring apparatus of description.

  Further, the power supply means for supplying a voltage to the transmission means, the reception means, the signal separation means, the delay means, the first time measurement means, the second time measurement means, and the calculation means, 8. The distance measuring device according to claim 1, wherein an electronic component that is always loaded is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it can avoid being influenced by the electronic component characteristic by the temperature change of an electronic component which comprises an electronic circuit, or a power supply variation, and can perform distance measurement with high precision.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a basic configuration example of a distance measuring apparatus according to the present invention.

The apparatus comprises processing means 1, wave sending means 2, branching means 3, wave receiving means 4, light projecting lens 5, condenser lens 7, optical delay means 8, power supply means 9, and measurement start switch 10. .
The processing unit 1 includes a calculation unit 11, a measurement gate 12, an electrical delay unit 13, a signal separation unit 14, a counter 15, and a crystal resonator 16.

The wave transmitting means 2 includes a laser drive circuit 21 and a semiconductor laser 22, the branching means 3 includes a half mirror 31, and the wave receiving means 4 includes a photodiode 41 and an amplifier.
An optical fiber or the like is used as the optical delay means 8, and a counter 15 having a clock function and programmable is used.

  When the measurement start switch 10 is pressed, a control signal is output from the calculation means 11 and a trigger signal is transmitted from the measurement gate 12 to the laser drive circuit 21. The laser drive circuit 21 transmits a drive signal to the semiconductor laser 22 by this trigger signal. When receiving the drive signal, the semiconductor laser 22 emits pulsed laser light. The emitted laser light is branched into an irradiation wave and a reference wave by the half mirror 31, and the irradiation wave passes through the light projection lens 5 and is irradiated onto the measurement object 6. The reflected wave reflected by the measurement object 6 passes through the condenser lens 6 and enters the photodiode 41. On the other hand, the reference wave reflected by the half mirror 31 is delayed by the optical delay means 8 and then enters the photodiode 41.

  In the photodiode 41, both the reflected wave and the reference wave are converted into an electric signal, sent to the amplifier 42, amplified by the amplifier 42, and transmitted to the signal separation means 14. The signal separating means has a mask function, and allows one of the received reflected wave signal and reference wave signal to pass through and removes the other signal. The switching of the mask state is performed by a control signal from the counter 15, and the switching pattern can be changed by programming the counter 15 in advance.

  For example, if the reference wave signal is initially set to be counted, the signal separation means 14 passes only the reference wave signal and supplies it to the counter 15 and the electrical delay means 13. The electrical delay means 13 supplies the laser drive circuit 21 with a signal given a delay time based on the reference wave signal. The laser drive circuit 21 receives this supply signal and sends a drive signal to the semiconductor laser 22. Then, the laser light passes through the measurement path as described above, and the reference wave signal is output again from the signal separation means 14, and the measurement operation is repeated.

  On the other hand, the counter 15 counts up the reference wave signal, and when a predetermined set value (for example, 30000 times) is reached, the time required to reach this set value is transmitted to the computing means 11, A command is issued to the signal separation means 14 to switch the mask state to a state in which only the reflected wave signal is allowed to pass. In response to this switching signal, the signal separation means 14 allows only the reflected wave signal to pass from the next reception signal. The same measurement process as described above is performed on the reflected wave signal. Therefore, the counter 15 serves as both the first time measuring means for measuring the period of the reflected signal component and the second time measuring means for measuring the period of the reference signal component.

  FIG. 2 is a time chart showing a state in which measurement is performed, and FIG. 3 shows the relationship between the measurement time of the reflected wave signal period and the reference wave signal period and the heat generation of the electrical delay means in FIG. The thermal curve shown is represented. FIG. 4 shows the measurement operation of the reflected wave signal cycle and the reference wave signal cycle. Hereinafter, the measurement operation will be described with reference to the drawings.

  The signal component drawn with a broken line in the time chart of FIG. 2 indicates that the signal component is masked in the signal separation unit 14 and cannot be passed (removed) after being input to the signal separation unit 14. When the delay time between the transmission signal from the semiconductor laser 22 and the received reference wave signal is Ta, the delay time between the reference wave signal and the next transmission signal is Td, and one period of the reference wave signal is T1, Ta is This corresponds to the delay time provided by the optical delay means 8, and Td corresponds to the delay time provided by the electrical delay means 13. Further, T1 = Ta + Td. For example, if the pulse width of the transmission signal is 4 ns, Td is optimally 800 ns.

  Similarly, if the delay time between the transmitted signal and the received reflected wave signal is Tb, the delay time between the reflected wave signal and the next transmitted signal is Td, and one period of the reflected wave signal is T2, Tb is the measurement target. This corresponds to the time required to obtain the distance of the object 6, and Td corresponds to the delay time given by the electrical delay means 13. Further, there is a relationship of T2 = Tb + Td. There is a time for the electric signal to be transmitted through the electronic circuit, but the transmission time is negligible compared to the delay time of the delay means, and a subtraction process is performed later, such as T1-T2. Since the influence is canceled out by this, the transmission time is not taken into consideration.

  Initially, in the signal separation means 14, only the reference wave is passed by the control signal from the counter 15. Therefore, the signal separation unit 14 separates the reference wave signal from the received signals (S1). The counter 15 counts the separated reference wave signal, and accumulates the reference wave reception time T1 (reference wave signal cycle) (S2). The reference wave signals are counted one after another, and it is determined whether or not a predetermined number of times is detected (S3), and the counter 15 counts until the predetermined number of times is reached. This measurement state is shown as measurement 1 in FIG.

When the predetermined number of times is reached, the counter 15 sends the measured accumulation time to the calculation means 11 and instructs the signal separation means 14 to pass only the reflected signal component.
In response to this command, the signal separation means 14 separates the reflected wave signal (S4). The counter 15 counts the separated reference wave signal, and accumulates the reflected wave reception time T2 (reflected wave signal period) (S5). The reflected wave signals are counted one after another, and it is determined whether or not a predetermined number of times is detected (S6), and the counter 15 counts until the predetermined number of times is reached. This measurement state is shown by measurement 2 in FIG.

When the predetermined number of times is reached, the counter 15 sends the measured accumulation time to the calculation means 11 and instructs the signal separation means 14 to pass only the reflected signal component again.
The calculating means 11 calculates Dn by subtracting a value obtained by subtracting the reflected wave accumulation time from the reference wave accumulation time from ΣTa (the total number of delay times given by the optical delay means 8) (S7).

  For example, if the predetermined number of times is n, the reference wave accumulation time = (n−1) × T 1 and the reflected wave accumulation time = (n−1) × T 2, so that Dn = ΣTa − ((n−1) × T 1 − (N−1) × T2).

Next, the signal separation means 14 separates the reflected wave signal (S8), the counter 15 counts the separated reference wave signal, and accumulates the reflected wave reception time T2 (reflected wave signal period) (S9).
The reflected wave signals are counted one after another, and it is determined whether or not a predetermined number (n times) has been detected (S10), and the counter 15 counts until the predetermined number is reached. This measurement state is shown by measurement 3 in FIG.

  If the predetermined number of times has been reached, the counter 15 sends the measured accumulation time to the calculation means 11 and instructs the signal separation means 14 to pass only the reference signal component. In response to this command, the signal separation means 14 separates the reference wave signal (S11). The counter 15 counts the separated reference wave signal, and accumulates the reference wave reception time T1 (reference wave signal cycle) (S2). The reference wave signals are counted one after another, and it is determined whether or not a predetermined number (n times) has been detected (S13), and the counter 15 counts until the predetermined number is reached. This measurement state is shown by measurement 4 in FIG.

If the predetermined number of times has been reached, the counter 15 sends the measured accumulation time to the calculation means 11, and the calculation means 11 calculates Dn as in step S7 (S14).
Dn = ΣTa − ((n−1) × T1− (n−1) × T2). It is determined whether the reference wave reception time T1 accumulation and the reflected wave reception time T2 accumulation have been performed a predetermined number of times (N times) (S15). If not, the process returns to S1.

In this way, after the reference wave reception time T1 is accumulated, the reflected wave reception time T2 is accumulated, and then Dn is calculated. Then, after the reflected wave reception time T2 is accumulated, the reference wave reception time T1 is accumulated, and then Dn is calculated. The measurement processing of the reference wave reception time T1 accumulation and the reflected wave reception time T2 accumulation is alternately repeated while the order is changed, such as the reflected wave reception time T2 accumulation and the Dn calculation after the time T1 accumulation.

Measurements 1 to 6 in FIG. 2 show how the measurement is repeated as described above.
When the number of reference wave reception time T1 accumulations and reflected wave reception time T2 accumulations reaches N, the calculated N maximum values and minimum values of Dn are removed (S16) and calculated (N-2). ) The average value of Dn is calculated and set to D (S17). The distance is calculated from D (S18). In S16, the maximum value and the minimum value of Dn are removed for the purpose of accurately measuring the distance by removing the measured abnormal value, but without removing the maximum value and the minimum value of Dn. An averaging process may be performed.

  FIG. 3 shows a thermal curve of the electrical delay means corresponding to the measurements 1 to 6 and the measurement results A to C performed in FIG. 2, but the heat generation is constant over time (the temperature is constant). It can be seen that the calorific value rises in a curve until it becomes constant. During the period in which this curve is drawn, since the temperature continues to rise, the characteristics of the electrical delay means change and the delay time fluctuates, which greatly affects the distance measurement.

  However, in the measurement result A, the reflected wave reception time T2 is accumulated after the reference wave reception time T1 is accumulated. In the measurement result B, the reference wave reception time T1 is accumulated after the reflection wave reception time T2 is accumulated. Since the reflected wave reception time T2 is accumulated after the reference wave reception time T1 accumulation, the influence of the delay time based on the temperature rise received by the reference wave reception time T1 accumulation and the temperature received by the reflected wave reception time T2 accumulation. The effect of the delay time based on the rise is offset in the same way, and distance measurement can be performed accurately.

  Incidentally, as described above, in measurement 1 to measurement 6 in FIG. 3, reference wave signal measurement, reflected wave signal measurement, reflected wave signal measurement, reference wave signal measurement, reference wave signal measurement, reflected wave signal measurement, and so on. FIG. 5 shows a state in which each loop switching time is kept constant by providing a predetermined time interval (loop switching time) during the switching of the measurement. In the figure, the reference signal loop specified number arrival time corresponds to the above-described measurement of the reference wave signal n times, and the reflected signal loop specified number of times arrival time refers to the measurement of the reflected wave signal n times. Equivalent to. By widening the loop switching time interval, it is possible to promote heat dissipation to the electronic components in the processing means 1 and prevent an extreme temperature rise. FIG. 6 shows the relationship between the heat generation amount of the electronic component and the loop switching time.

  A signal portion surrounded by a broken line corresponds to a loop switching time interval, and the other time corresponds to a portion performing a measurement operation. It can be seen that during the loop switching time, heat is released and the calorific value is slightly reduced. By keeping each loop switching time interval constant, at the start of the next specified number of loops, it is possible to make the heat generation state at the same level as at the start of the previous specified number of loops, and measure the distance without being affected by the heat generation state be able to. As an example of a signal to be used, when the reference signal loop prescribed number arrival time is about 15 ms, 560 μs is optimal as the loop switching time interval.

FIG. 7 is a flowchart showing a procedure for performing the pseudo distance measurement operation in the configuration of FIG. 1, and FIG. 8 shows a time chart of the basic signal. The pseudo distance measurement operation is almost the same as a normal distance measurement operation, but the difference is that the calculation means 11 does not calculate the distance to the measurement object 6.

  When the measurement start switch 10 is turned on (S31), the normal distance measurement operation starts as described above, and the reflected wave from the measurement object 6 and the reference wave from the half mirror 31 are received and separated by the signal separation unit 14. The counter 15 performs counting. Initially, the reference wave signal is separated and received (S32), and reference wave reception time accumulation is performed (S33). When the reference wave reception is not counted a predetermined number of times (S34 NO), the next reference wave signal is repeatedly received.

  On the other hand, when the reference wave reception is counted a predetermined number of times (S34 YES), the reception is switched to the reception of the reflected wave (S35) and the reflected wave reception signal is accumulated (S36). When the reflected wave reception is not counted a predetermined number of times (S37 NO), the next reflected wave signal is repeatedly received. When the reflected wave reception is counted a predetermined number of times (S37 YES), the next reception is also performed in the reflected wave reception state (S38), and the reflected wave reception signal is accumulated (S39). When the reflected wave reception is counted a predetermined number of times (YES in S40), the reception is switched to the reference wave reception (S41), and the reflected wave reception signal is accumulated (S42).

  When the reference wave reception is counted a predetermined number of times (YES in S43), it is detected whether the reference wave reception time accumulation and the reflected wave reception time accumulation are performed a predetermined number of times (S44). Reference wave reception time accumulation and reflected wave reception time accumulation are performed, and if the predetermined number of times has been reached, if a predetermined time has elapsed since the measurement start switch 10 was turned on (YES in S45), normal distance measurement processing (S46).

  As can be seen from the time chart of FIG. 8, a pulsed laser is emitted from the semiconductor laser 22 to obtain a reflected wave and a reference wave so as to perform a normal distance measurement process. Since the original distance measurement processing operation is performed after driving the wave transmitting means 2, the wave receiving means 4, etc., the heat generation state of the electronic components in the processing means 1 can be kept constant, and the distance The measured value can be stabilized.

  FIG. 9 shows that the signal can be output from the measurement gate 12 to the calculation means 11 so that the signal can be transmitted from the electrical delay means 13A to the measurement gate 12 so that the signal can be supplied from the measurement gate 12 to the electrical delay means 13A. Wiring is performed. A certain signal is looped in the order of the calculation means 11, the measurement gate 12, and the electrical delay means 13A. FIG. 10 shows a circuit configuration for performing this signal loop.

  The electrical delay means 13A includes an electrical delay circuit section 131 that performs the same delay processing as the electrical delay means 13 of FIG. 1, and a NOT circuit 132 and an AND circuit 133 that are newly added unlike the electrical delay means 13. , AND circuit 134. FIG. 12 is a flowchart showing the operation of the circuit of FIG. 8, and FIG. 11 is a basic signal time chart. This will be described with reference to these drawings.

A drive signal and a control signal are transmitted from the calculation means 11 to the measurement gate 12 (S21). A drive signal is supplied from the measurement gate 12 to the electrical delay circuit unit 131 to perform delay processing. The signal given the delay time is sent to the input terminal of the AND circuit 133. On the other hand, the control signal transmitted to the measurement gate 12 is HIGH and is input to the input terminal of the AND circuit 134.
Since one of the input terminals of the AND circuit 134 is HIGH, a signal given a delay time is output from the output terminal of the AND circuit 134.

  In the other transmission route, the control HIGH signal is inverted by the NOT circuit 132 to become a LOW signal and then input to the input terminal of the AND circuit 133. Therefore, the gate of the AND circuit 133 is closed and the AND circuit 133 is closed. No signal with a delay time is output from the output terminal.

  The computing means 11 checks the output signal from the AND circuit 134 every 100 μS (S22, S23), and if the output signal from the AND circuit 134 arrives through the measurement gate 12, the circuit propagates within the processing means. The process proceeds to S24. When the signal does not reach the computing means 11, for example, the signal is checked after waiting for 100 μS. When the signal arrives, it is detected whether or not the measurement start switch 10 is turned on (S24). If the measurement start switch 10 is not turned on, the second drive signal is transmitted from the computing means 11 to perform delay processing, and The same processing is performed. When the measurement start switch 10 is turned on, normal distance measurement processing is performed (S25).

  That is, as shown in FIG. 11, until the normal distance measurement process starts (until the measurement start switch 10 is turned ON), the driving signal is continuously transmitted from the calculation means 11 at a constant period (for example, 800 ns), and the calculation is performed. The signal is looped in the order of the means 11, the measurement gate 12, and the electrical delay means 13A. When the measurement start switch 10 is turned on, the drive signal from the calculation means 11 is stopped and the control signal is set to LOW. Since the gate of the AND circuit 133 is opened and the gate of the AND circuit 134 is closed, normal distance measurement processing can be performed.

  In this way, by operating a part of the processing means before the normal distance measurement processing, even if the heat generation state of the electronic component has shifted to the normal distance measurement stage, it is compared with the heat generation state before the transition As a result, a sudden change does not occur, so that fluctuations in the characteristics of the electronic component are reduced, and the measurement value can be stabilized.

  Since the loop signal cycle can be changed by changing the drive signal cycle, it can be changed by the control of the calculation means 11. For example, the period of the loop signal is set so as to drive the calculation means 11, the measurement gate 12, and the electrical delay means 13A so as to be in the state closest to the heat generation state of the electronic component when the normal distance measurement stage is entered. May be.

  FIG. 13 is obtained by adding a temperature sensor 17 to the configuration of FIG. 9 and adding a signal line for supplying a control signal from the calculation means 11 to the power supply means 9. The temperature sensor 17 is disposed near the electrical delay unit 13, detects the temperature in the processing unit 1, and transmits a detection signal to the sequential calculation unit 11. The period of the signal that loops with the calculation means 11, the measurement gate 12, and the electrical delay means 13A is changed according to the temperature detected by the temperature sensor 17. FIG. 14 shows a procedure for changing the loop signal period in accordance with the detected temperature.

  When the measurement start switch is turned on (S51), the temperature inside the processing means is detected by the temperature sensor 17 (S52). When the detected temperature is equal to or larger than TMP1 (S53), the loop signal cycle is set to F1, which is the larger one (S54). If the detected temperature is between TMP2 and TMP1 (S55), the loop signal cycle is set to an intermediate value. F2 is set (S56), and when the detected temperature is lower than TMP2, the loop signal cycle is set to F3, which is smaller (S57). S59 and subsequent steps are the same as the processing in FIG.

  Here, there is a relationship of F3 <F2 <F1. For example, when TMP1 = 30 degrees and TMP2 = 20 degrees are set, F3 = 500 ns, F2 = 800 ns, and F1 = 1000 ns.

  As described above, if the detection temperature is high, the loop signal cycle is lengthened to reduce the heat generation amount of the electronic component, and if the detection temperature is low, the loop signal cycle can be shortened to increase the heat generation amount. The temperature in the processing means can be adjusted accurately, and distance measurement that is not affected by fluctuations in the heat generation state can be performed.

FIG. 15 shows a procedure for changing the number of loops of the loop signal in accordance with the detected temperature.
When the measurement start switch is turned on (S71), the temperature in the processing means is detected by the temperature sensor 17 (S72). If the detected temperature is equal to or greater than TMP1 (S73), the loop count is set to the smaller CNT1 (S74). If the detected temperature is between TMP2 and TMP1 (S75), the loop count is set to the intermediate CNT2. (S76) When the detected temperature is lower than TMP2, the larger number of loops is set to CNT3 (S77). S79 and subsequent steps are the same as the processing in FIG.

  Here, there is a relationship of CNT1 <CNT2 <CNT3. For example, when TMP1 = 30 degrees and TMP2 = 20 degrees are set, CNT1 = 10 times, CNT2 = 20 times, and CNT3 = 40 times.

  As described above, if the detection temperature is high, the number of loops of the loop signal is decreased to reduce the heat generation amount of the electronic component, and if the detection temperature is low, the number of loops of the loop signal is increased to increase the heat generation amount. Therefore, the temperature in the processing means can be adjusted accurately, and distance measurement that is not affected by fluctuations in the heat generation state can be performed.

  FIG. 16 shows a specific configuration in which the power supply voltage of the power supply means 9 is controlled by a control signal from the calculation means 11. A power supply IC is used as the power supply means 9, and the voltage can be appropriately changed by a CPU control signal of the calculation means 11. The changed power supply voltage is the processing means 1, the transmission means 2, the reception wave. Supplied to means 4.

  FIG. 17 shows the operation of the power supply means 9 according to the control signal. When the measurement start switch is turned on (S91), the temperature in the processing means is detected by the temperature sensor 17 (S92). When the detected temperature is equal to or greater than TMP1 (S93), the calculation means 11 transmits the control signal 1 to the power supply means (S94), and if the detected temperature is between TMP2 and TMP1 (S95), the calculation means. 11 transmits the control signal 2 to the power supply means (S96), and when the detected temperature is lower than TMP2, the calculation means 11 transmits the control signal 3 to the power supply means (S97). After the waiting time has elapsed (S98), a distance measurement procedure (S99) is performed.

  If the detected temperature is high, the value of the power supply voltage of the power supply means 9 is considered to be larger than the reference value, so the control signal 1 controls the power supply voltage to decrease. Since it is standard that the detected temperature is between TMP2 and TMP1, the control signal 2 is a signal that does not adjust the power supply voltage. If the detected temperature is low, the value of the power supply voltage is considered to be lower than the reference value, so the control signal 3 is controlled to increase the power supply voltage.

  For example, when TMP1 = 30 degrees and TMP2 = 20 degrees, the control signal 3 is increased by 0.2 volts from the power supply reference voltage so that the control signal 1 is lowered by 0.2 volts from the power supply reference voltage. Set to

  As described above, since the power supply voltage can be automatically adjusted according to the ambient temperature condition, the distance measuring operation can be performed without being affected by the heat generation state.

  FIG. 18 shows a configuration in which a load is provided inside the power supply means 9. A resistor R is connected in parallel to the power supply voltage generating portion. Since a current always flows through the resistor R and the current is consumed, it can be buffered even when the processing means operates and a load fluctuation occurs suddenly. Therefore, the stability of the power supply state is maintained, and the distance measurement can be performed stably. For example, when the processing means is constituted by CPLD and the power supply is 1.8 volts, R can be 100Ω.

It is a figure which shows the basic structural example of the distance measuring device by this invention. It is a time chart figure which shows the state in which the measurement of a reference wave signal and a reflected wave signal is performed. It is a figure which shows the relationship between the measurement of FIG. 2, and the heat_generation | fever of an electrical delay means. It is a flowchart figure which shows a distance measurement process operation. It is a time chart figure which shows the state at the time of switching with reference wave signal measurement and reflected wave signal measurement. It is a time chart which shows the heat_generation | fever state of the process means corresponding to FIG. It is a flowchart figure which shows the state which performs a pseudo measurement operation | movement before a distance measurement process operation start. FIG. 8 is a time chart showing the relationship of basic signals in FIG. 7. It is a figure which shows the example comprised so that a signal might loop within a processing means. It is a figure which shows the specific structural example of the signal loop part of FIG. It is a time chart figure of the basic signal of FIG. It is a flowchart figure which shows the operation | movement of the structure of FIG. It is a figure which shows the structure which installed the temperature sensor in the structure of FIG. It is a flowchart figure which shows the operation | movement which changes a loop signal period with the detection temperature of a temperature sensor. It is a flowchart figure which shows the operation | movement which changes the loop frequency | count of a loop signal with the detection temperature of a temperature sensor. It is a figure which shows the specific structural example which changes the power supply voltage of a power supply means. FIG. 17 is a flowchart showing an operation for changing a power supply voltage in the configuration of FIG. 16. It is a figure which shows the structural example of the power supply means provided with load. It is a figure which shows the conventional distance measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing means 2 Wave transmission means 3 Branch means 4 Wave receiving means 5 Light projection lens 6 Measuring object 7 Condensing lens 8 Optical delay element 9 Power supply means 10 Measurement start switch 11 Calculation means 12 Measurement gate 13 Electrical delay means 14 Signal separating means 15 Counter 16 Crystal resonator 21 Laser drive circuit 22 Semiconductor laser 31 Half mirror 41 Photo diode 42 Amplifier

Claims (9)

A transmitting means for periodically transmitting a pulsed electromagnetic wave; a receiving means for receiving a reflected wave reflected by the object to be measured; a part of the transmitted electromagnetic wave; Branching means for entering the receiving means as:
A signal separating means for separating a signal received by the wave receiving means into a reflected signal component from a measurement object and a reference signal component corresponding to a reference wave;
A delay unit that gives a predetermined delay time using the reflected signal component or the reference signal component separated by the signal separation unit as a reference signal, and transmits the signal as a drive signal to the transmission unit;
First timing means for adding a predetermined number of cycles of the reflected signal component;
Second time measuring means for adding a predetermined number of cycles of the reference signal component;
The measurement object is based on a difference between a predetermined number of addition periods of the reflected signal component measured by the first time measuring means and a predetermined number of addition periods of the reference signal component measured by the second time measuring means. A calculation means for calculating the distance to the object,
When the first time measuring means and the second time measuring means are repeatedly used in succession, the distance is measured repeatedly by changing the order of measurement by the first time measuring means and the second time measuring means. measuring device.   2. The distance measuring apparatus according to claim 1, wherein an interval of a switching time between the measurement performed by the first time measuring unit and the measurement performed by the second time measuring unit is made constant.   Before starting the measurement operation process for calculating the distance to the measurement object, the transmission means, reception means, signal separation means, delay means, first time measurement means, and second time measurement means are driven. The distance measuring apparatus according to claim 1, wherein a pseudo distance measuring operation is performed.   Before starting the measurement operation process for calculating the distance to the measurement object, at least the delay unit is driven so that a signal loops between the calculation unit and the delay unit. The distance measuring device according to claim 1, wherein the distance measuring device is characterized in that:   5. The distance measuring device according to claim 4, wherein frequency control is performed by the calculating means so that the loop signal becomes a signal having a predetermined frequency.   6. The distance according to claim 5, further comprising a temperature sensor installed to measure a temperature in the vicinity of the delay means, and controlling a frequency of the loop signal in accordance with a detected temperature from the temperature sensor. measuring device.   The temperature sensor installed for measuring the temperature of the vicinity of the delay means is provided, and the number of loops of the loop signal is changed according to the detected temperature from the temperature sensor. Distance measuring device.   A temperature sensor installed to measure the temperature in the vicinity of the delay means, and according to the detected temperature from the temperature sensor, the transmission means, the reception means, the signal separation means, the delay means, the first The distance measurement according to any one of claims 1 to 2, wherein the supply voltage of the power supply means for supplying voltage to the time measuring means, the second time measuring means, and the computing means is controlled. apparatus.   The power transmitting means, the receiving means, the signal separating means, the delay means, the first timing means, the second timing means, and the power supply means for supplying voltage to the computing means are provided with electronic components that are always loaded. The distance measuring device according to any one of claims 1 to 7, wherein the distance measuring device is provided.

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