WO2016175301A1 - 発光装置および距離測定装置 - Google Patents
発光装置および距離測定装置 Download PDFInfo
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- WO2016175301A1 WO2016175301A1 PCT/JP2016/063407 JP2016063407W WO2016175301A1 WO 2016175301 A1 WO2016175301 A1 WO 2016175301A1 JP 2016063407 W JP2016063407 W JP 2016063407W WO 2016175301 A1 WO2016175301 A1 WO 2016175301A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/22—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-emitting devices, e.g. LED, optocouplers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/484—Transmitters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/497—Means for monitoring or calibrating
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0057—Temporal shaping, e.g. pulse compression, frequency chirping
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
- H01S5/0057—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping for temporal shaping, e.g. pulse compression, frequency chirping
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
- H01S5/06835—Stabilising during pulse modulation or generation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
- H01S5/06837—Stabilising otherwise than by an applied electric field or current, e.g. by controlling the temperature
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/504—Laser transmitters using direct modulation
Definitions
- the present invention relates to a light emitting device that performs pulsed light emission.
- FIG. 1 shows the relationship between drive current and output light in an LD (laser diode).
- LD laser diode
- a method is used in which a drive current is allowed to flow during an extremely short time ⁇ t to emit only the first pulsed light.
- ⁇ t has a time width on the order of several tens to several hundreds of picoseconds, and it is difficult to generate a pulsed drive current having a time width ⁇ t with a simple circuit.
- the characteristics of LD change with temperature. Specifically, even under the same light emission conditions, the waveform of the light emission pulse and the light emission peak intensity change depending on the temperature.
- the effect of temperature on the characteristics can be said for various electronic devices such as resistors, capacitors, and transistors.
- the emission intensity and pulse waveform of measurement pulse light affect the distance measurement range and distance measurement accuracy.
- a method for avoiding the influence of temperature a method of keeping the LD and the light source driving circuit at a constant temperature by using a constant temperature means for keeping the temperature constant so as not to be affected by the temperature change can be considered.
- the constant temperature means has a complicated structure using a heater and a Peltier element, and has a problem that it is expensive and consumes a large amount of power.
- an object of the present invention is to provide a technique for suppressing variation in the waveform of a light emission pulse in a light emitting device caused by various factors.
- the invention according to claim 1 is a light source in which relaxation oscillation occurs immediately after energization, a light source driving circuit in which a switching element for voltage application is connected in series to a differential circuit in which a resistor and a capacitor are connected in parallel, A power source for applying a voltage to a series circuit in which the light source and the light source driving circuit are connected in series, a pulsed light detecting unit for detecting pulsed light emitted from the light source, and the pulse detected by the pulsed light detecting unit And a voltage control unit that controls a voltage applied to the light source in accordance with a light waveform.
- the light emission waveform is detected, and the voltage applied to the light source is feedback-controlled so that the light emission waveform becomes a waveform satisfying a specific condition.
- a difference in light emission waveform difference in peak value or difference in shape due to the influence of temperature and the influence of component accuracy is corrected by adjusting the voltage applied to the light source.
- a resistor is an electronic device that exhibits a predetermined electrical resistance. Examples of the resistor include various resistance elements available as resistance devices, resistors using wiring, and resistors using various conductors and semiconductors. The resistor generally exhibits an electrical resistance characteristic according to Ohm's law, but a non-linear element such as a diode or a three-terminal element such as an FET with an appropriate bias set can be used as the resistor.
- a capacitor is an electronic device having a predetermined electric capacity and a function of accumulating electric charges.
- a capacitor an element that can be obtained as a capacitor device, a capacitance between wiring patterns, a capacitance constituted by a pair of conductors with an insulator interposed therebetween, a capacitance between a coaxial cable or two cables covered with insulation, and the like are used. be able to.
- the series connection of the light source and the light source driving circuit is basically a directly connected structure, but a configuration in which the light source and the light source driving circuit are connected in series via another electronic device is also possible.
- the impedance of the capacitor is smaller than that of the resistor
- an inrush current flows into the capacitor of the differentiation circuit.
- This inrush current flows to the light source connected in series with the light source driving circuit.
- a voltage due to the inrush current is applied to the light source.
- the voltage at this time is set so as to exceed a threshold value at which the light source emits light, and the light source emits light due to the inrush current to the capacitor.
- the inrush current to the capacitor is instantaneous, and the inrush current disappears when charge is accumulated in the capacitor.
- the inrush current to the capacitor decreases, a potential difference occurs between both ends of the resistor connected in parallel with the capacitor, so that current starts to flow through the resistor instead of the inrush current to the capacitor.
- the current flowing through the resistor flows through the light source, a voltage drop occurs at the resistor, so that the voltage applied to the light source is smaller than the voltage resulting from the inrush current to the capacitor.
- various parameters are set so that the voltage to the light source, which is reduced by the voltage drop across the resistor, is below the light emission threshold. For this reason, light emission from the light source stops when a current starts to flow through the resistor.
- the first pulse emission is performed according to the generation of the inrush current to the capacitor described above, and
- the second and subsequent pulse emission is set to stop in accordance with the stop and generation of the current flowing through the resistor.
- Various parameters are determined through preliminary experiments.
- a temperature detection unit is provided, and the voltage control unit controls the voltage applied to the light source based on the temperature detected by the temperature detection unit. It is characterized by performing. According to the research of the present inventor, it has been found that the relationship between the temperature required to obtain a specific light emission pulse waveform and the voltage applied to the light source can be roughly specified with respect to a specific light source. By utilizing this relationship, in the invention according to claim 2, the relationship between the temperature and the applied voltage necessary for obtaining a specific pulse waveform is acquired in advance, and based on the temperature information detected by the temperature detection unit, Determine the voltage applied to the light source. Since there are variations in the characteristics of the light source itself, the accuracy of other parts such as resistors and capacitors, and changes in characteristics due to temperature, the correction according to the invention of claim 2 is not complete, and only a certain degree of accuracy can be pursued. Stop.
- the voltage control unit is configured to control the voltage applied to the light source so that the peak intensity value of the pulsed light falls within a predetermined range. Control is performed.
- the peak intensity of the pulsed light output from the light source is detected, and the voltage applied to the light source is adjusted so that the peak intensity falls within a predetermined range. Note that control within a specific range includes control with a specific value.
- the voltage control unit is configured so that the waveform of the pulsed light has a waveform that satisfies a specific condition.
- the voltage applied to the light source is controlled.
- the shape of the waveform of the pulsed light output from the light source is evaluated, and the value of the voltage applied to the light source is set so that the shape of the waveform of the pulsed light satisfies a specific condition. change. By doing so, it is possible to reduce the influence of temperature and component accuracy on the shape of the pulse waveform.
- the invention according to claim 5 is the invention according to claim 4, wherein the voltage control unit controls a voltage applied to the light source so that a waveform of the pulsed light has a single peak.
- the pulsed light used for ranging is preferably a single peak shape. However, if the light emission condition deviates from the ideal condition due to the influence of temperature change or component accuracy, the effect of relaxation oscillation appears, and the pulsed light may deviate from a single peak shape and multiple peaks may appear. Therefore, in the invention described in claim 5, unimodal pulsed light is obtained by controlling the voltage applied to the light source so as to obtain unimodality.
- the invention described in claim 6 is the invention described in claim 4 or 5, wherein the voltage controller controls the voltage applied to the light source based on the symmetry of the waveform of the pulsed light. And It is desirable that the pulsed light used for distance measurement has a right and left symmetrical waveform. However, when the light emission condition deviates from the ideal condition due to the influence of temperature change and component accuracy, the symmetry of the pulsed light waveform is lost. Therefore, in the invention described in claim 6, the symmetry of the pulsed light is evaluated by evaluating the symmetry of the pulsed light under a specific condition, and the value of the voltage applied to the light source is controlled based on the result, thereby suppressing the collapse of the symmetry of the pulsed light. .
- the invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the bias voltage applied to the switching element is changed simultaneously when the output voltage of the power supply changes. And
- a bias voltage is applied to the control electrode (base electrode or gate electrode) of the switching device to turn on / off the threshold.
- stable voltage light is emitted by applying a voltage from a power source to a series circuit in which a light source and a differentiation circuit are connected in series, and changing this voltage depending on the situation.
- the power ON / OFF switching element is connected in series between the series circuit (series circuit in which the light source and the differentiation circuit are connected in series) and the power circuit, and the connection between the series circuit and the power circuit is ON. / OFF is performed. Therefore, when the output voltage of the power supply voltage is changed, the voltage applied to the switching element (for example, the voltage between the source and the drain in the case of an FET) also changes.
- the bias voltage is a fixed voltage
- the threshold voltage to ground potential changes according to the change in the voltage applied to the transistor, and it is always ON, or always OFF, and it does not turn ON or OFF when it should be turned ON.
- ON / OFF control can be performed at a desired timing even if the power supply voltage changes.
- the invention according to claim 8 is an emission which is generated from the light emitting device according to any one of claims 1 to 7 and emits light by the first oscillation of the relaxation oscillation of the light source toward the measurement object.
- a light receiving unit that receives reflected light reflected from the measurement object, and a signal processing unit that calculates a distance to the measurement object based on an output signal of the light receiving unit. It is a distance measuring device.
- the variation in the waveform of the light emission pulse in the light emitting device caused by various factors can be suppressed.
- FIG. 4 is a graph (A) showing a relationship between temperature and applied voltage when light emission is performed with a constant peak value of emission intensity, and a waveform diagram (B) showing a light emission waveform according to temperature.
- FIG. 3 is a block diagram (A) illustrating a part of the circuits in the block diagrams (A) and (A) of the light-emitting device of the embodiment.
- FIG. 4 shows the configuration of the light emitting device including the optical system. 3 and 4 show the light emitting device 100.
- the light emitting device 100 has a configuration in which a light source 101, a differentiation circuit 102, and a switch 103 are connected in series.
- the light source driving circuit 104 is configured by connecting the differentiation circuit 102 and the switch 103 in series.
- a power supply voltage V is applied from the power supply circuit 105 to both ends of a circuit in which the light source 101 and the light source driving circuit 104 are connected in series.
- FIG. 3 shows an example in which a plus voltage is applied. However, a configuration in which a minus potential is applied with the light source side as the ground potential and the switch side as the minus potential is also possible.
- the light source 101 is a laser diode (LD).
- the differential circuit 102 is a circuit in which a resistor R (102a) and a capacitor C (102b) are connected in parallel, and a circuit having a characteristic that a pulsed current (differential current) flows when a voltage is applied with the switch 103 turned ON.
- the switch 103 is an FET, and performs an ON / OFF operation in response to a drive signal from the switch drive circuit 106. When the switch 103 is turned on, the voltage V from the power supply circuit is applied to a series circuit in which the light source 101 and the differentiation circuit 102 are connected in series.
- the power supply circuit 105 is a power supply that can vary the output voltage.
- the light emitting device 100 includes a light receiving element 107, an A / D converter 108, a calculation unit 109, and a temperature sensor 110.
- the light receiving element 107 receives a part of the light emitted from the light source 101 and converts it into an electric signal.
- a photoelectric conversion element such as an APD (avalanche photodiode) is used.
- the A / D converter 108 converts the output of the light receiving element 107 into a digital signal. This digital signal becomes waveform data including information on the waveform of the pulsed light from the light source 101 detected by the light receiving element 107.
- the digital signal output from the A / D converter 108 is sent to the arithmetic unit 109.
- the arithmetic unit 109 is hardware that functions as a computer, and includes a CPU, a RAM, a ROM, other arithmetic circuits and storage circuits, various interface circuits, or an FPGA that can constitute these.
- the calculation unit 109 performs the following processing. (1) Determination of light emission timing. (2) Detection of the waveform of the light emission pulse light output (light emission) from the light source 101 based on the output of the A / D converter 108. (3) Determination of the output voltage of the power supply circuit 105 based on the detected waveform of the light emission pulse light. (4) Determination of the output voltage of the power supply circuit 105 based on the temperature detected by the temperature sensor 110. (5) Control of the power supply circuit 105.
- the temperature sensor 110 detects the temperature in the light emitting device 100 and sends the detected temperature data to the calculation unit 109.
- the temperature sensor 110 is arranged so that the temperature of the light source 101 (laser diode: LD), which is the device most affected by temperature, can be detected with high accuracy.
- a part of the pulsed light emitted from the light emitting element 101 is reflected by the semi-transmissive mirror 111 toward the reflecting mirror 112, and the light enters the light receiving element 107.
- the semi-transmission mirror 111 reflects, for example, several percent of the amount of incident light and transmits the rest.
- the reflection mirror 112 is a normal reflection mirror.
- the switch drive circuit 106 receives the light emission signal from the calculation unit 109, and outputs a switch drive voltage (for example, the switch drive voltage in FIG. 10) for determining ON / OFF of the switch 103.
- the circuit constant of the differentiation circuit 102 is an example, but the power supply voltage is 5 V, the resistance value of the resistor 102a is 200 ohms, the capacitance of the capacitor 102b is 22 pF, and the frequency is about several tens of MHz as a light emission signal that determines the ON / OFF timing. An example of using a rectangular wave with an upper limit of is given.
- the inrush current is rapidly reduced.
- the current flowing through the resistor 102b increases.
- the current flowing into the capacitor 102b stops, and the current flowing through the resistor 102a and the current flowing through the light source 101 have the same value.
- the value of the power supply voltage (V) and the values of the capacitor 102b and the resistor 102a are set so that the charging time (the time during which the inrush current flows) to the capacitor 102b becomes substantially the same value as ⁇ t in FIG. Yes.
- a voltage drop occurs in the resistor 102a when the inrush current stops flowing to the capacitor 102b, and the voltage applied to the light source 101 is reduced due to this voltage drop.
- the resistor 102a stops the light emission of the light source 101 due to this voltage drop. Values and other parameter values are selected.
- the inrush current stops flowing to the capacitor 102b
- a current flows to the resistor 102a, and the current flowing to the light source 101 is suppressed (limited) by the resistor 102a.
- the LD current flowing to the light source 101 is reduced.
- the value of the resistor 102a and other parameters are set so that the value is lower than the light emission threshold.
- the light source 101 emits light when the capacitor 102b is charged, and the voltage applied to the light source 101 is reduced (current value is reduced) due to the voltage drop (current limit) generated in the resistor 102a immediately thereafter. Then, the light emission of the light source 101 stops. As a result, the occurrence of relaxation oscillation shown in FIGS. 1 and 2 is suppressed, and only the first pulse emission in the period of ⁇ t is performed.
- FIG. 5 shows changes in voltage applied to each part.
- FIG. 5 shows the case where a positive power supply is used.
- FIG. 5A shows a voltage Vcs on the light source 101 side of the differentiating circuit 102.
- V ⁇ Vcs is a voltage applied to the light source 101.
- FIG. 5B shows a voltage applied to the differentiating circuit 102, that is, a voltage Vdif applied to the resistor 102a and the capacitor 102b.
- FIG. 5C shows a voltage Vd (voltage applied between the source and drain) applied to the switch (FET) 103.
- the inrush current gradually decreases, and on the other hand, the current flowing through the resistor 102a increases correspondingly.
- a voltage drop occurs in the resistor 102a, and the voltage applied to the light source 101 decreases. That is, the influence of the voltage drop generated by the resistor 102a in the power supply voltage V becomes stronger, and the voltage applied to the light source 101 is reduced accordingly.
- the voltage drop generated in the resistor 102a increases the value of Vcs (see period 115 in FIG. 5A), and the voltage applied to the light source 101 (V ⁇ Vcs) decreases accordingly.
- the resistance value of the resistor 102a and other parameters are set so that (V-Vcs) falls below the light emission threshold. Accordingly, the light source 101 emits light in the period 114 in FIG. 5A and light emission stops in the period 115.
- the values of the resistor 102a and the capacitor 102b of the differentiating circuit 102 so that the period 114 is as long as ⁇ t in FIG. 2, light emission of only one pulse at the start of light emission is achieved. Done.
- the switch 103 when the switch 103 is turned on again, the same operation as described above is repeated, and the second pulse emission is performed by the light source 101.
- the light source 101 by repeatedly turning on / off the switch 103, the light source 101 repeatedly emits pulses.
- the peak value of the pulsed light and the values of C and R have the following general relationship. • Increase the intensity of the optical pulse ⁇ Increase C and decrease R • Reduce the intensity of the optical pulse ⁇ Reduce C and increase R
- C and R are correlated, they are not uniquely determined.
- FIG. 6 shows the difference in the waveform of the light emission pulse when the temperature of the LD and the light source drive circuit is changed. As shown in FIG. 6, when the LD temperature is different, the waveform of the light emission pulse is different. Note that the second pulse of relaxation oscillation appears in the waveform of the light emission pulse at low temperature (0 ° C.).
- FIG. 7A shows the relationship between the temperature and the power supply voltage when the power supply voltage VEE is changed so that the light emission peak value is the same even if the LD temperature is different.
- FIG. 7B shows the difference in waveform at that time.
- the waveform of the light emission pulse also changes when the temperature changes.
- the shape of the waveform including the peak value of the light emission pulse of the light source 101 changes.
- adjusting the power supply voltage slightly sacrifices the similarity in the shape of the output waveform, but aligns the peak values. Can do.
- the voltage applied to the light source 101 is appropriately changed according to the temperature change even if the temperature changes, (1) Although the peak values are different, the shape of the pulse waveform can be made similar. (2) Although the similarity of the shape of the pulse waveform is broken, the peak value can be made the same. (3) The similarity between the peak value and the pulse waveform can be within a specific range.
- the above (3) is a pattern in which both (1) and (2) are combined to pursue both the uniformity of peak values and the similarity of waveforms. Further, a pattern that gives priority to the uniformity of the peak value and also considers the similarity of the waveform shape, and a pattern that gives priority to the similarity of the waveform shape and takes the uniformity of the peak value into consideration are also possible. Further, it is possible to control the voltage applied to the light source 101 so that the symmetry of the pulse waveform is not lost.
- the processing relating to the control of the waveform of the light emission pulse described above is performed in the calculation unit 109 of FIG.
- a program for determining the procedure of processing performed by the calculation unit 109 is stored in a storage unit inside the calculation unit 109 and is read out and executed in an appropriate storage area.
- a form in which the program is stored in an appropriate storage medium and provided from the storage medium is also possible.
- a method of changing the voltage applied to the light source 101 a configuration of changing the output voltage of the power supply circuit 105 is employed.
- a variable resistance element is arranged in the circuit, a voltage drop is generated there, and the resistance value of the variable resistance element is adjusted, thereby applying the voltage applied to the light source 101. It is also possible to change the configuration.
- the correction of the light emission pulse waveform is performed as follows. First, the light source 101 emits pulses. Then, the emitted light is detected by the light receiving element 107, and the waveform data of the light emission pulse light detected from the output of the light receiving element 107 is obtained. The calculation unit 109 determines whether or not the waveform of the light emission pulse light satisfies a specific condition. If the waveform does not satisfy the specific condition, the output voltage (power supply voltage) of the power supply circuit 105 is set so as to satisfy the specific condition. ) And fire again.
- Examples of adjusting the power supply voltage include the following. (1) The power supply voltage is adjusted so as to maintain a specific peak power. (2) The power supply voltage is adjusted so that the light emission pulse has a single peak. (3) The power supply voltage is adjusted so that left-right symmetry of the light emission pulse shape is ensured. (4) The power supply voltage is adjusted according to the measured temperature.
- FIG. 15 shows an example of the case where the pulse waveform is corrected so as to suppress the occurrence of relaxation oscillation and to make the single peak appear more clearly by lowering the power supply voltage and lowering the peak value of the waveform. . Note that when the power supply voltage is adjusted according to the temperature of (4), errors due to variations in component characteristics, changes with time, and the like occur, but the approximate reproducibility of the pulse waveform can be obtained.
- the control (4) is further performed in advance. Specifically, first, the light emission pulse waveform is roughly corrected by the control of (4), and then the light emission pulse waveform is precisely corrected by a method combining one or more of (1) to (3). . Details of a specific correction procedure will be described later.
- FIG. 8A shows the first configuration.
- digital data specifying a voltage is output from the arithmetic unit 109 (see FIG. 3) and input to the power supply circuit 105.
- the power supply circuit 105 includes a D / A converter 105a and a switching power supply IC 105b that can variably control the voltage output by the control voltage.
- the digital data specifying the voltage output from the calculation unit 109 is converted into an analog voltage signal by the D / A converter 105a, and input to the switching power supply IC 105b.
- the switching power supply IC 105b outputs an output voltage having a value corresponding to the analog voltage (control voltage) output from the D / A converter. In this way, the voltage determined by the calculation unit 109 is output from the power supply circuit 105.
- a PWM signal corresponding to the voltage designated from the calculation unit 109 (see FIG. 3) is output.
- the PWM signal is set to a pulse width corresponding to a designated voltage (the voltage finally output from the power supply circuit 105 determined by the calculation unit 109).
- the power supply circuit 105 includes a low-pass filter 105c and a switching power supply IC 105b.
- the PWM signal output from the calculation unit 109 is converted into an analog voltage by the low-pass filter 105c, and an output voltage corresponding to the analog voltage is output from the switching power supply IC 105b.
- the voltage determined by the arithmetic unit 109 is output from the power supply circuit 105.
- a switch drive voltage for controlling the light emission of the light source 101 is input to the switch drive circuit 106 for driving the FET constituting the switch 103, and a bias voltage for determining the operation condition of the FET is supplied from the bias circuit. Supplied.
- the bias circuit generates a bias voltage Vb obtained by dividing the power supply voltage VEE by the resistors R1 and R2. Vb is applied as a bias voltage to the gate of the FET. In this configuration, when the power supply voltage VEE changes, the bias voltage Vb also changes accordingly.
- FIG. 10 shows a switch drive voltage (a waveform of a drive signal applied to the gate electrode of the FET), Vth (threshold voltage of the FET), Vb (bias voltage applied to the gate electrode of the FET) when the configuration of FIG. 9 is adopted. ), The relationship of VEE (power supply voltage) is shown.
- FIG. 10 shows a case where a negative power source is used. *
- the peak value Vp of the switch drive voltage is set to be a value larger than Vth ⁇ Vb with reference to Vb.
- the FET 103 is turned on during the period when Vp is applied to the gate, and the FET 103 is turned off during other periods.
- the FET 103 repeats ON / OFF at the timing of the waveform of the illustrated switch drive voltage.
- the switch drive voltage can be turned on at the timing when the FET 103 is turned on, and can be turned off at the timing when the FET 103 is turned off.
- Vb when the VEE is not divided to create Vb, but Vb is set to a constant value independent of VEE independently of VEE, the following problems occur.
- the values of Vb and Vp are fixed values and do not follow the fluctuation of VEE.
- the value of Vth changes following the change in VEE. Therefore, Vp ⁇ Vth as shown in FIG. 11A, and the FET is not turned on at the timing when it should be turned on, or Vb> Vth as shown in FIG. 11B, and the FET is always turned on. Inconvenience arises.
- the FET switch 103
- the light source 101 does not emit light, and if the FET is always on, the light source 101 may emit light continuously.
- Vb is not linked to VEE, the light emission control is hindered.
- correction processing processing for determining the output voltage of the power source 105 in FIG. 3
- This correction processing is performed at one or a plurality of timings when a temperature change of a specific width at the time of turning on the power is detected when the user instructs the processing every time a certain time elapses when the power is turned on. .
- FIG. 12 shows an example of the correction process procedure.
- the process is started, first, information on the temperature measured by the temperature sensor 110 is acquired (step S101). Next, a power supply voltage corresponding to the temperature acquired in step S101 is selected from the relationship between the temperature and the power supply voltage necessary to obtain a specific peak output acquired in advance (step S102), and the selected power supply By outputting the voltage from the power supply circuit 105, the light source 101 emits pulses (step S103). The light emission in step S103 is performed for experimentally evaluating the waveform of the light emission pulse. In this light emission, single-pulse light emission is performed according to the principle described with reference to FIG.
- the calculation unit 109 acquires information relating to the waveform of the light emission pulse from the output of the light receiving element 107 (step S104).
- pulse light emission is continuously performed a plurality of times, and data of each light emission pulse is acquired.
- the width of the light emission pulse (width on the time axis) is about 100 ps to 300 ps (picosecond) (see FIG. 6).
- the sampling interval can be set to 125 ps by using four A / D converters having a sampling interval of 500 ps and performing sampling by a time interleave method.
- the time resolution can be further reduced to 1/10 ps of 1/10.
- 20 sampling points can be secured in the 250 ps width, and the waveform of the light emission pulse can be detected with high accuracy.
- step S104 a process for obtaining data relating to the shape of the waveform of the light emission pulse shown in FIG. 6 is performed in step S104.
- step S105 a determination is made as to whether or not the light emission pulse waveform satisfies a specific condition. This determination has the following three modes.
- (First determination mode) It is determined whether the peak value of the waveform of the light emission pulse falls within a predetermined range or is a value equal to or greater than a predetermined value. In this case, when the peak value of the waveform of the light emission pulse is within a predetermined range, or when the peak value is equal to or larger than the predetermined value, the determination in step S105 is YES, and otherwise, the determination is NO. It becomes.
- (Second determination mode) It is determined whether or not the waveform of the light emission pulse has a single peak. Whether or not it is a single peak is determined by checking whether or not there is one peak. In this case, the determination is YES when it is determined to be a single peak, and the determination is NO when there are two or more peaks. The peak is determined by the presence or absence of an inflection point where the sign of the value obtained by time differentiation of the waveform is reversed from positive to negative.
- the position of the peak of the pulse waveform on the time axis is obtained.
- the deviation of the waveform distribution on the left and right (before and after in terms of time) on the time axis is calculated.
- the difference between the left and right areas of the waveform is used as an index for evaluating the deviation of the waveform distribution.
- the light emission pulse waveform is determined to have a symmetric shape. If the deviation between the left and right distributions of the light emission pulse waveform exceeds a predetermined threshold, the light emission pulse waveform is determined to be an asymmetric waveform.
- Only one of the first determination mode to the third determination mode may be employed, or a plurality of the determination modes may be used in combination.
- the process which makes the determination which concerns on all three, and makes the determination of step S105 YES when at least one is YES is also possible.
- the intensity of the distance measurement pulsed light is important, and therefore the first determination condition is made strict.
- the emission intensity is important, the relaxation oscillation will adversely affect the ranging accuracy, and the waveform shape is also important, so relax the conditions for unimodality and waveform symmetry.
- the falling of the pulse is remarkably gradual and may affect the ranging accuracy, but the evaluation of the third determination is performed even when the evaluation of the second determination cannot be used because it is a single peak. By using it, the pulse waveform can be corrected.
- step S105 If it is determined in step S105 that the waveform of the light emission pulse acquired in step S104 satisfies a specific condition, there is no need for further correction regarding the waveform of the light emission pulse, and the correction process is terminated (step S106). On the other hand, if it is determined in step S105 that the waveform of the light emission pulse acquired in step S104 does not satisfy a specific condition, the process proceeds to step S107 to perform processing for correcting the waveform of the light emission pulse to a shape that satisfies the condition.
- step S107 the value of the output voltage of the power supply circuit 105 in FIG. 3 is selected based on the waveform of the light emission pulse acquired in step S104.
- processing for determining the power supply voltage is performed based on basic data on the relationship between the light emission waveform and the power supply voltage obtained in advance.
- basic data for example, (1) to increase or decrease the peak value of the light emission waveform, to increase or decrease the power supply voltage; (2) to increase the single peak characteristic of the light emission waveform, to increase or decrease the power supply voltage; (3)
- basic data for example, (1) to increase or decrease the peak value of the light emission waveform, to increase or decrease the power supply voltage; (2) to increase the single peak characteristic of the light emission waveform, to increase or decrease the power supply voltage; (3)
- In order to increase the symmetry of the light emission waveform there is data relating to matters such as whether to increase or decrease the power supply voltage.
- the basic data is prepared for each temperature (for example, every 1 ° C. step), and is stored in advance in an appropriate storage area in the calculation unit 109.
- the difference between the waveform shape of the light emission pulse obtained in step S104 and the target waveform shape is evaluated, and information on the power supply voltage necessary to reduce the difference is obtained from the basic data. obtain.
- the power supply voltage value to be changed is selected based on the correlation between the peak value checked in advance and the power supply voltage.
- the power supply voltage value to be changed is selected based on the correlation between the peak value checked in advance and the power supply voltage.
- information on whether the power supply voltage should be increased or decreased when the peak value is insufficient is acquired, and a new Select the power supply voltage.
- the power supply voltage may be adjusted with priority given to any of the three elements of peak value, symmetry, and relaxation oscillation. For example, in the long-distance search mode, the light emission peak value is given priority. Therefore, the power supply voltage is first changed so that the peak value of the light emission pulse waveform falls within a specified range or value. Then, at the stage where the emission peak satisfies the specified condition, the power supply voltage is adjusted for other requirements within a range where the condition does not collapse.
- step S107 the process after step S103 is performed using the changed power supply voltage. Since the influence of the power supply voltage affects each of the peak value, unimodality, and waveform symmetry, not all conditions can be satisfied with a single correction. In this case, the width of the change in the power supply voltage is narrowed and the adjustment in step S107 is performed again, and the processes in and after step S103 are performed again. In this way, by repeating the process from step S107 ⁇ step S103 ⁇ step S104 one or more times, the power supply voltage that obtains the waveform of the light emission pulse that satisfies the specific condition is searched.
- step S105 does not become YES after repeating the process a certain number of times, as a next best measure, the determination condition of step S105 is relaxed, the required level related to the light emission pulse waveform is lowered, and the process of step S105 and subsequent steps is performed. Further, in the processing after step S107, the tendency of the waveform change may be detected by finely varying the power supply voltage, and the power supply voltage having the desired waveform shape may be searched by trial and error. In this case, the number of times of light emission necessary for correction increases, but fine correction according to the situation becomes possible. *
- FIG. 13A shows an example in which the light source 101, the switch 103, and the differentiation circuit 102 are arranged in series from the positive potential side.
- FIG. 13B shows an example in which the switch 103, the light source 101, and the differentiation circuit 102 are arranged in series from the positive potential side.
- a light source driving circuit is configured by the differential circuit 102 and the switch 103 that are indirectly connected in series with the light source 101 interposed therebetween.
- the light source 101 is equivalently connected in series to a light source driving circuit constituted by the differentiation circuit 102 and the switch 103.
- the power supply circuit is not shown.
- FIG. 13 shows a configuration in which a positive potential is applied as the power supply voltage.
- the power supply (+ V) portion is grounded (set to the ground potential), and the GND portion is minus.
- a configuration using a negative power source for applying a potential is also possible. This is the same in the case of FIG.
- FIG. 14 shows a distance measuring device 500.
- the distance measuring device 500 is a device that measures the distance to a measurement object using laser light.
- the distance measuring device 500 includes a light emitting device 100, an emitting unit 501, a light receiving unit 502, a signal processing unit 503, and a display unit 504.
- the light emitting device 100 has the configuration shown in FIGS. Of course, other light-emitting devices exemplified in this specification can be used.
- the emission unit 501 includes an optical system for emitting laser light output from the light emitting device 100 to the measurement target.
- the light receiving unit 502 includes an optical system and a light receiving element (such as a photodiode), and receives reflected light emitted from the emitting unit 501 and reflected by the object.
- the signal processing unit 503 calculates the distance to the object based on the detection light received by the light receiving unit 502. The calculation performed by the signal processing unit 503 is the same as that in a normal laser distance measuring device.
- the display unit 504 is a display device such as a liquid crystal display, and displays the distance to the object calculated by the signal processing unit 503.
- the distance measuring device 500 uses distance measuring light with a short pulse width generated by the light emitting device 100, high distance measuring accuracy can be obtained. Further, since the light emitting device 100 has a simple structure, low power consumption, and can be obtained at low cost, the distance measuring device 500 can be downsized, low power consumption, and low cost.
- the laser distance measuring device is illustrated as an application example of the light source of the present invention.
- the light source of the present invention that performs pulsed light emission using a differentiating circuit is a variety of devices using pulsed light (for example, laser processing devices). Etc.).
- DESCRIPTION OF SYMBOLS 100 Light-emitting device, 101 ... Light source (laser diode: LD), 102 ... Differentiation circuit, 102a ... Resistance, 102b ... Capacitor, 103 ... Switch (FET), 104 ... Light source drive circuit, 111 ... Semi-transmission mirror, 112 ... Mirror 500 ... Distance measuring device.
- Light source laser diode: LD
- 102 Differentiation circuit
- 102a ... Resistance
- 102b ... Capacitor
- FET Switch
- FET Switch
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Abstract
Description
(構成)
図3には、実施形態の発光装置のブロック図(A)と(A)における一部の回路を記載したブロック図(B)が示されている。図4には、光学系も含めた発光装置の構成が記載されている。図3および図4には、発光装置100が示されている。発光装置100は、光源101、微分回路102、スイッチ103が直列に接続された構成を有している。微分回路102とスイッチ103とが直列に接続されることで光源駆動回路104が構成されている。光源101と光源駆動回路104が直列接続された回路の両端に電源回路105から電源電圧Vが加えられている。図3には、プラス電圧を加える例が示されているが、光源側をアース電位とし、スイッチ側をマイナス電位として、マイナス電位を加える構成も可能である。
(1)発光タイミングの決定。
(2)A/Dコンバータ108の出力に基づく光源101から出力(発光)される発光パルス光の波形の検出。
(3)検出した発光パルス光の波形に基づく電源回路105の出力電圧の決定。
(4)温度センサ110が検出した温度に基づく電源回路105の出力電圧の決定。
(5)電源回路105の制御。
スイッチ103がOFF(ソース・ドレイン間が非導通)の状態において、光源101と微分回路102には、電圧Vは加わらず、光源101は発光しない。スイッチ103をONにすると、電圧Vが加わってコンデンサ102bに電荷が流れ込み、突入電流が生じ、光源101に駆動電流が流れる。この駆動電流により、光源101が発光する。
コンデンサC(102b)の値と抵抗R(102a)の値を設定する指針を下記に示す。
(1)Cの最小値 : LDに発振しきい値電流以上の電流が流せる容量値。
(小さ過ぎると、LDが発振しない)
(2)Cの最大値 : 緩和振動の1番目のパルスのみを生成して2番目以降
のパルスを抑制するような電流を流せる容量値(Rとの
依存性あり)。
(大き過ぎると、緩和振動が発生する)
(3)Rの最小値 : LD電流が発振しきい値電流と等しくなる抵抗値。
(小さ過ぎると、緩和振動が生じる)
(4)Rの最大値 : Rで発生する電圧降下と電源電圧との差が、LD順方
向電圧と等しくなる抵抗値(Cとの依存性あり)。
(大き過ぎると、次パルスまでの間の放電が間に合わな
くなる)
・光パルスの強度を大きく ⇒ Cを大きく,Rを小さく
・光パルスの強度を小さく ⇒ Cを小さく,Rを大きく
ただし、CとRには相関があるため一意的には決まらない。また、緩和振動の抑制効果との関係も考慮して、CとRの値を決める必要がある。
特定のパルス波形を得るCRの設定とLDの特性の組み合わせは許容範囲が狭い。したがって、試作品で最適な組み合わせを見出しても、量産品において部品の特性のバラツキがあると、光源101から発光されるパルス光の波形が変化する。同じ型番のLDで同じ発光条件であっても、LDの製造ロットが異なると、特性の差異によってパルス波形は変化する。特に温度変化を受けると、各部品(特に光源(LD)101)の特性が変化し、それがパルス波形の形状に大きく影響する。
図6に示すように、同じ発光条件であっても温度が変わると発光パルスの波形も変化する。他方で、発光のために光源に加えられる電圧を変えると、光源101の発光パルスのピーク値も含めた波形の形状が変化する。他方で、図7(B)に示すように、温度が違う場合であっても、電源電圧を調整することで、出力波形の形状の類似性はやや犠牲となるが、ピークの値を揃えることができる。以上の現象を利用することで、温度が変化しても光源101への印加電圧を温度の変化に応じて適切に変化させると、
(1)ピーク値は異なるが、パルス波形の形状を相似にできる。
(2)パルス波形の形状の相似性は崩れるが、ピーク値を同じにできる。
(3)ピーク値とパルス波形の相似性を特定の範囲に収めることができる。
(1)特定のピークパワーを維持するように電源電圧を調整する。
(2)発光パルスが単峰になるように電源電圧を調整する。
(3)発光パルス形状の左右の対称性が確保されるように電源電圧を調整する。
(4)計測した温度に応じて電源電圧を調整する。
図15には、電源電圧を下げ、波形のピークの値を下げることで、緩和振動の発生を抑え、単峰性がより明確に現れる様にパルス波形を補正した場合の例が示されている。なお、(4)の温度に応じて電源電圧を調整した場合、部品特性のばらつきや経時変化等による誤差が生じるが、大凡のパルス波形の再現性は得られる。
以下、電源回路105の出力電圧を可変する構成について説明する。図8(A)には、第1の構成が記載されている。図8(A)の構成では、演算部109(図3参照)から電圧を指定するデジタルデータが出力され、それが電源回路105に入力される。電源回路105は、D/Aコンバータ105aと、制御電圧によって出力する電圧を可変制御できるスイッチング電源IC105bを備えている。
図9に示すように、スイッチ103を構成するFETを駆動するスイッチ駆動回路106には、光源101の発光を制御するスイッチ駆動電圧が入力され、またFETの動作条件を決めるバイアス電圧がバイアス回路から供給される。バイアス回路は、電源電圧VEEを抵抗R1とR2で分圧したバイアス電圧Vbを作り出す。VbがFETのゲートにバイアス電圧として印加される。この構成では、電源電圧VEEが変化すると、それに連動してバイアス電圧Vbも変化する。
以下、処理の手順の一例を説明する。以下に説明する処理は、演算部109において実行される。また、以下に説明する処理の手順を決めるプログラムは、適当な記憶領域や記憶媒体に記憶され、演算部109によって実行される。
発光パルスの波形のピークの値が、予め定めた範囲に収まるか、あるいは予め定めた値以上の値であるか否かを判定する。この場合、発光パルスの波形のピークの値が、予め定めた範囲に収まっている場合、あるいは予め定めた値以上の値である場合にステップS105はYESの判定となり、そうでない場合にNOの判定となる。
発光パルスの波形の形状が単峰であるか否かを判定する。単峰であるか否かは、ピークが1つであるか否かを見ることで判定される。この場合、単峰であると判定された場合にYESの判定となり、2以上のピークがある場合にNOの判定となる。なお、ピークは、波形を時間微分した値の符号が正から負に逆転する変曲点の有無により判定される。
発光パルスの形状の時間軸上における対称性を評価し、対称性が予め定めた条件を満たすものである場合に、対称形状と判定し、そうでない場合に非対象形状と判定する。この場合、対象形状と判定された場合にYESの判定となる。
上述した構成によれば、温度変化や部品精度の誤差による影響を電源電圧の変更により抑えることができる。また、部品の特性の経時変化の影響による発光パルス波形の変化を適宜補正することができる。このため、部品の設定や選別、および装置の調整に係るコストが抑えられる。また、特定の性能が恒常的に得られる優位性が得られる。特に、測距装置に用いた場合、恒温装置を用いずに温度の影響を抑えられるので、低コスト、低消費電力で高性能な測距装置を得ることができる。
光源101、微分回路102、スイッチ103の直列接続の順序は、図3の構成に限定されず、図13(A)や(B)の構成も可能である。図13(A)には、プラス電位側から、光源101、スイッチ103、微分回路102と直列に配置された例が示されている。図13(B)には、プラス電位側から、スイッチ103、光源101、微分回路102と直列に配置された例が示されている。この場合、光源101を挟んで間接的に直列接続された微分回路102とスイッチ103により光源駆動回路が構成される。また、光源101は、微分回路102とスイッチ103により構成される光源駆動回路に等価的に直列接続された状態となる。なお、図13では、電源回路は図示省略されている。図13には、電源電圧としてプラス電位を加える構成が記載されているが、例えば、図13(A)の構成で電源(+V)の部分を接地し(アース電位とし)、GNDの部分にマイナス電位を加えるマイナス電源を用いる構成も可能である。これは、図13(B)の場合も同じである。
図14には、測距装置500が示されている。測距装置500は、レーザ光を用いて測定対象物までの距離の測定を行う装置である。測距装置500は、発光装置100、射出部501、受光部502、信号処理部503および表示部504を備えている。
Claims (8)
- 通電直後に緩和振動が発生する光源と、
抵抗とコンデンサが並列に接続された微分回路に、電圧印加のためのスイッチング素子が直列に接続された光源駆動回路と、
前記光源と前記光源駆動回路が直列に接続された直列回路に電圧を加える電源と、
前記光源から発光されるパルス光を検出するパルス光検出部と
前記パルス光検出部が検出した前記パルス光の波形に対応させて前記光源に加えられる電圧を制御する電圧制御部と
を備えることを特徴とする発光装置。 - 温度検出部を備え、
前記電圧制御部は、前記温度検出部が検出した温度に基づいて前記光源に加えられる電圧の制御を行うことを特徴とする請求項1に記載の発光装置。 - 前記電圧制御部は、前記パルス光のピーク強度の値が予め定めた範囲となるように前記光源に加えられる電圧の制御を行うことを特徴とする請求項1または2に記載の発光装置。
- 前記電圧制御部は、前記パルス光の波形の形状が特定の条件を満たす波形となるように前記光源に加えられる電圧の制御を行うことを特徴とする請求項1~3のいずれか一項に記載の発光装置。
- 前記電圧制御部は、前記パルス光の波形が単峰になるように前記光源に加えられる電圧の制御を行うことを特徴とする請求項4に記載の発光装置。
- 前記電圧制御部は、前記パルス光の波形の対称性に基づいて前記光源に加えられる電圧の制御を行うことを特徴とする請求項4または5に記載の発光装置。
- 前記電源の出力電圧が変化した際に前記スイッチング素子に加えるバイアス電圧を同時に変化させることを特徴とする請求項1~6のいずれか一項に記載の発光装置。
- 請求項1~請求項7のいずれか1つに記載の発光装置から生成され、前記光源の緩和振動の最初の発振による光を測定対象物に向け射出する射出部と、
前記測定対象物から反射した反射光を受光する受光部と、
前記受光部の出力信号に基づいて前記測定対象物までの距離の算出を行う信号処理部と
を備えることを特徴とする距離測定装置。
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DE102021120225A1 (de) * | 2021-08-04 | 2023-02-09 | Valeo Schalter Und Sensoren Gmbh | Verfahren zum Betreiben einer Sendeeinrichtung für elektromagnetische Signale, Sendeeinrichtung, Detektionsvorrichtung und Fahrzeug |
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US20180109073A1 (en) | 2018-04-19 |
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