KR100984295B1 - Distance/speed meter and Distance/speed measuring method - Google Patents

Abstract

The present invention is to shorten the measurement time in the distance / speed meter and distance / speed measurement method capable of measuring not only the distance to the measurement target which is stopped by using the interference of light but also the speed of the measurement target. The first and second semiconductor lasers 1-1 and 1-2 for emitting the first and second laser light, and at least the first semiconductor laser so that the oscillation period in which the oscillation wavelength is continuously monotonically increased is repeatedly present. A first laser driver 4-1 for driving, a second laser driver 4-2 for driving the second semiconductor laser so that the increase and decrease of the first semiconductor laser and the oscillation wavelength are reversed, and at least the first First and second receivers 2-1 and 2-2 for converting the light output of the second semiconductor laser into an electrical signal and included in the output signals of the first and second receivers; The distance from the measurement object of the 2nd laser beam and each laser beam Counting means 13 for counting the number of the interference waveforms generated by the turning light, the minimum oscillation wavelength and the maximum oscillation wavelength of the first and second semiconductor lasers, and the counting result of the counting means, the distance from the measurement object and the measurement Computing means (8) for calculating at least one of the target speeds.

Odometer, Speedometer

Description

Distance / speed meter and distance / speed measuring method

The present invention relates to a distance / speedometer and a distance / speed measurement method for measuring at least one of a distance to a measurement target and a speed of the measurement target using interference of light.

Since distance measurement using interference of light by laser is a non-contact measurement, it has been used for a long time as a highly accurate measuring method without disturbing the measurement object. In recent years, semiconductor lasers have been used as light measurement light sources due to miniaturization of devices. A representative example is the use of an FM heterodyne interferometer. This allows relatively long distance measurement and high precision, but there is a problem that the optical system is complicated because an interferometer is used outside the semiconductor laser.

On the other hand, a measuring instrument using the interference (magnetic coupling effect) inside the semiconductor laser of the output light of the laser and the return light from the measurement target is a rangefinder using the magnetic coupling effect of the semiconductor laser (Ueda again, Yamada 쥰, Shito) Susumu, 1994 Japanese Association of Electrical Relations Society Tokai-Ichibu Association Conference, 1994), `` Study on a Compact Rangefinder Using the Magnetic Coupling Effect of Semiconductor Lasers '' (Yamada 쥰, Shito Susumu, Noda Tsuda, Ueda Uda) Japanese Aichi Institute of Technology Research Report, No. 31B, p.35 ~ 42, 1996), and 'laser diode self-mixing technique for sensing applications' No. Mitchell Norgia, Silva Donati, Thierry Bosch, Optical Journal A: Pure Practical Optics, p. 283-294, 2002).

According to such a self-coupled laser meter, since the semiconductor laser with a photodiode functions as a light emission, an interference, and a light receiving function, an external interference optical system can be greatly simplified. Therefore, the sensor portion is composed only of the semiconductor laser and the lens, and is compact in comparison with the conventional one. In addition, the distance measurement range is wider than the triangulation method.

39 shows a multiple resonator model of an FP type (Fabry-Perot) type semiconductor laser. A part of the reflected light from the measurement object 104 tends to return to the oscillation area. The fine light returned is combined with the laser light in the semiconductor laser resonator 101, resulting in unstable operation and generating noise (multiplexer noise or return light noise). The change in characteristics of the semiconductor laser caused by the return light is remarkable even when the amount of return light relative to the output light is very small. This phenomenon is not limited to Fabry-Perot type semiconductor lasers (hereinafter referred to as FP type), but is a vertical cavity surface emitting laser type (hereinafter referred to as VCSEL type) and distributed feedback laser (Distributed FeedBack laser). And other types of semiconductor lasers, such as the DFB laser type).

When the oscillation wavelength of the laser is λ and the distance from the cleaved surface 102 of the semiconductor crystal closer to the measurement object 103 to the measurement object 104 is L, when the following resonance conditions are satisfied, the return light and the resonator ( 101) The laser light inside meets strongly, and the laser power increases slightly.

L = qλ / 2

In Equation 1, q is an integer. This phenomenon can be sufficiently observed because the amplification action occurs because the apparent reflectance in the resonator 101 of the semiconductor laser increases even if the scattered light is very weak from the measurement object 104.

Since the semiconductor laser emits laser light whose frequency varies depending on the magnitude of the injection current, an external modulator is not required to modulate the oscillation frequency, and can be directly modulated by the injection current. FIG. 40 is a diagram showing the relationship between the oscillation wavelength and the output waveform of the photodiode 103 when the oscillation wavelength of the semiconductor laser is changed at a certain ratio. When L = qλ / 2 shown in Equation 1 is satisfied, the phase difference between the return light and the laser light in the resonator 101 becomes 0 ° (in phase), so that the return light and the laser light in the resonator 101 meet most strongly. When L = qλ / 2 + λ / 4, the phase difference becomes 180 ° (inverse phase), so that the return light and the laser light in the resonator 101 meet the weakest. For this reason, when the oscillation wavelength of the semiconductor laser is changed, a place where the laser output becomes strong and a weak place appear repeatedly alternately. When the laser output at this time is detected by the photodiode 103 provided in the resonator 101, As shown in FIG. 40, the staircase waveform of a fixed period is obtained. Such waveforms are generally called interference stripes.

This stepped waveform, that is, each interference stripe, is called a mode hop pulse (hereinafter referred to as MHP). MHP is a different phenomenon from the mode hopping phenomenon. For example, when the distance to the measurement object 104 is L1, and the number of MHPs is ten, the number of MHPs becomes five at half distance L2. That is, when the oscillation wavelength of a semiconductor laser is changed at a certain time, the number of MHPs changes in proportion to the measurement distance. Therefore, when the MHP is detected by the photodiode 103 and the frequency of the MHP is measured, distance measurement can be easily performed.

In the self-coupled laser measuring instrument, since the interference optical system outside the resonator can be greatly simplified, the device can be miniaturized, and a high speed circuit is not required, and there is an advantage in that it is strong against disturbance light. In addition, since the return light from the measurement object may be very weak, there is an advantage that it is not affected by the reflectance of the measurement object, that is, does not cover the measurement object. However, in the conventional interference type measuring instrument including the magnetic coupling type, although the distance to the stationary measurement object can be measured, there is a problem that the distance of the measurement object having the speed cannot be measured.

Therefore, the present inventor has proposed a distance / speed meter that can measure not only the distance to a stationary measurement object but also the speed of the measurement object, as shown in Japanese Patent Laid-Open No. 2006-313080. The structure of this distance / speedometer is shown in FIG. The distance / speed meter of FIG. 41 includes a semiconductor laser 201 that emits laser light to a measurement object, a photodiode 202 that converts light output of the semiconductor laser 201 into an electrical signal, and a semiconductor laser 201. Light is collected and irradiated to the measurement object 210, and the return light from the measurement object 210 is collected and incident on the semiconductor laser 201 and the oscillation wavelength is generated by the semiconductor laser 201. A laser driver 204 for alternately repeating a first oscillation period that is continuously increasing and a second oscillation period where the oscillation wavelength is continuously decreasing, and a current-voltage conversion amplifier for converting and amplifying the output current of the photodiode 202 into voltage. 205, a signal extraction circuit 206 for differentiating the output voltage of the current-voltage conversion amplifier 205 twice, and a coefficient for counting the number of MHPs included in the output voltage of the signal extraction circuit 206. Between the circuit 207 and the measurement target 210 Li and the calculator 208 for calculating a speed of the measurement target 210, and has a display device 209 for displaying the calculation result of the calculating device 208. The

The laser driver 204 supplies the semiconductor laser 201 as an injection current with a triangular wave driving current that repeatedly increases or decreases at a constant rate of change with respect to time. As a result, the semiconductor laser 201 is driven to alternately repeat the first oscillation period in which the oscillation wavelength continuously increases at a constant rate of change and the second oscillation period in which the oscillation wavelength is continuously reduced at a constant rate of change. FIG. 42 is a diagram showing a time variation of the oscillation wavelength of the semiconductor laser 201. In Fig. 42, P1 is the first oscillation period, P2 is the second oscillation period, λa is the minimum value of the oscillation wavelength in each period, λb is the maximum value of the oscillation wavelength in each period, and T is the period of the triangular wave.

The laser light emitted from the semiconductor laser 201 is collected by the lens 203 and enters the measurement object 210. The light reflected from the measurement object 210 is collected by the lens 203 and incident on the semiconductor laser 201. The photodiode 202 converts the light output of the semiconductor laser 201 into a current. The current-voltage conversion amplifier 205 converts the output current of the photodiode 202 into a voltage and amplifies it, and the signal extraction circuit 206 differentiates the output voltage of the current-voltage conversion amplifier 205 twice. The counting circuit 207 counts the number of MHPs included in the output voltage of the signal extraction circuit 206 for each of the first oscillation period P1 and the second oscillation period P2. The computing device 208 is characterized by the number of MHPs in the minimum oscillation wavelength lambda a and the maximum oscillation wavelength lambda b and the first oscillation period P1 and the MHP in the second oscillation period P2 of the semiconductor laser 201. Based on the number, the distance from the measurement object 210 and the speed of the measurement object 210 are calculated.

According to the distance / speed meter disclosed in Japanese Patent Laid-Open No. 2006-313080, the distance to the measurement object and the speed of the measurement object can be simultaneously measured. However, in this distance / speedometer, for example, at least three times of the first oscillation period t-1, the second oscillation period t, and the first oscillation period t + 1, for example, to measure the distance or the speed. Since the number of MHPs must be counted over, there was a problem that the time required for the measurement was long.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in the distance / speed meter and the distance / speed measurement method capable of measuring not only the distance to a stationary measurement object but also the speed of the measurement object by using the interference of light, It aims to shorten time.

In order to achieve this object, the distance / speedometer according to the present invention, The first semiconductor laser 1-1 emitting the first laser light to the measurement object 11 and the second semiconductor laser 1-2 emitting the second laser light in parallel with the first laser light to the measurement object. And a first laser driver 4-1 for driving the first semiconductor laser so that the oscillation period in which the oscillation wavelength is continuously monotonically increased is repeatedly present. A second laser driver 4-2 for driving the second semiconductor laser so as to be reversed, a first light receiver 2-1 for converting at least the light output of the first semiconductor laser into an electrical signal, and at least the The second light receiver 2-2 for converting the light output of the second semiconductor laser into an electrical signal, and the first laser light included in the output signal of the first light receiver and the return light from the measurement target of the laser light. Of the number of interference waveforms generated by the second receiver Counting means (13) for counting the number of interference waveforms generated by the second laser light and the return light from the measurement target of the laser light included in the output signal, and the minimum oscillation wavelength of the first and second semiconductor lasers, respectively. And calculating means (8) for calculating at least one of the maximum oscillation wavelength and the distance between the object to be measured and the speed of the object to be measured from the counting result of the counting means. In the first counting period shorter than the oscillation period, the number of interference waveforms included in the output signal of the light receiver corresponding to the semiconductor laser of which the oscillation wavelength is increasing among the first and second semiconductor lasers is obtained, and the first coefficient is obtained. In the second counting period at the same time as the period, the first and second semiconductor lasers are included in the output signal of the light receiver corresponding to the semiconductor laser whose oscillation wavelength is decreasing. And calculating the number of interference waveforms, wherein the calculating means is based on the minimum and maximum oscillation wavelengths of the first and second semiconductor lasers and the counting result of the counting means. Distance / speed calculating means 81 for calculating a speed candidate value of the state; Based on the determination result of the state determination means, distance / speed determination means 86 and 86a for determining at least one of the distance to the measurement object and the speed of the measurement object are provided.

In addition, the distance / speed measurement method according to the present invention comprises the steps of driving the first semiconductor laser emitting the first laser light to the measurement object repeatedly so that at least the oscillation wavelength continuously monotonically increases the oscillation period, and the measurement object Driving a second semiconductor laser that radiates a second laser light in parallel with the first laser light so that the increase and decrease of the oscillation wavelength is reversed, and included in the output signal of the first light receiver; The number of interference waveforms generated by the first laser light and the return light from the measurement target of the laser light, the second laser light included in the output signal of the second receiver and the return light from the measurement target of the laser light. A counting step of counting the number of interference waveforms generated by the interference wave, and interference of the minimum and maximum oscillation wavelengths of the first and second semiconductor lasers and the first and second laser beams, respectively. A calculation step of calculating at least one of a distance to the measurement object and a speed of the measurement object from the counting result of the mold, wherein the counting step is performed in a first counting period shorter than an oscillation period of the first and second semiconductor lasers. The number of interference waveforms included in the output signal of the light receiver corresponding to the semiconductor laser having the increased oscillation wavelength among the first and second semiconductor lasers is obtained, and at the same time as the first counting period, The method of claim 1, wherein the number of interference waveforms included in the output signal of the light receiver corresponding to the semiconductor laser of which the oscillation wavelength is decreasing among the first and second semiconductor lasers is included. 2 The distance candidate value and the speed candidate of the measurement object based on the minimum oscillation wavelength and the maximum oscillation wavelength of the semiconductor laser and the counting result of the counting means. Based on the determination result of the distance / speed calculation step of calculating a value, the speed candidate value calculated in the distance / speed calculation step, a state determination step of determining a state of a measurement target, and the state determination step, And a distance / speed determination step of determining at least one of the distance to the object and the speed of the measurement object.

Since the interference type rangefinder is an absolute condition in which the measurement object is stationary when the distance is measured, the distance from the measurement object having the velocity cannot be measured. In contrast, the present invention can also measure the distance to a measurement target that is not stationary. That is, according to the present invention, the speed (size, direction) and the distance of the measurement target can be measured simultaneously. Further, in the present invention, the first and second semiconductor lasers having opposite oscillation wavelengths are radiated in parallel to each other to simultaneously radiate laser beams to the measurement object, and the interference wavelengths included in the output signals of the first and second light receivers. The number of times is counted for each of the output signals of the first and second receivers, whereby the distance and the speed can be measured in a shorter time than before.

In the present invention, when the state of the measurement object cannot be determined based on the speed candidate value, the state of the measurement object is determined by using the calculation result of the hysteresis displacement calculation means, and the distance from the measurement object and the measurement object. We can calculate the speed of.

In the present invention, the period of the interference waveform in the counting period is measured, and the frequency distribution of the period of the interference waveform in the counting period is prepared from the measurement result, and the median value of the interference waveform period is calculated from the frequency distribution. From the frequency distribution, the sum Ns of the degrees of the class that is equal to or less than the first predetermined multiple of the median value and the sum Nw of the degrees of the class that are greater than or equal to the second predetermined multiples of the median value are calculated. By correcting the counting result of the means, it is possible to eliminate the influence of missing or excessive coefficients at the time of counting and correct the counting error of the interference waveform, thereby improving the measurement accuracy of distance and speed.

In the present invention, instead of counting the number of the interference waveforms by the counting means, the period of the predetermined number of interference waveforms included in the output signal of the first and second receivers is measured, and from the measurement result, The frequency distribution of the period of the interference waveform is created, the median of the period of the interference waveform is calculated from the frequency distribution, and from the frequency distribution, the sum Ns of the degrees of the class less than or equal to the first predetermined multiple of the median and the second predetermined multiple of the median By calculating the sum Nw of the above-described degrees and correcting a predetermined number of interference waveforms based on the sum Ns and Nw, the measurement error of the number of interference waveforms per unit time can be reduced, and the measurement accuracy of distance and speed can be reduced. It can be further improved.

Further, in the present invention, the determination result of the state determination means, the distance / speed determination means, among the speed candidate values when the measurement object is assumed to be in the small displacement state and the speed candidate values when the measurement object is assumed to be in the displacement state. The speed candidate value which is determined not to be the real value and is not employed is approximately equal to the value obtained by multiplying the wavelength change rate of the first and second semiconductor lasers by determining that the distance / speed determination means is a real value. By adjusting the amplitude of at least one of the drive currents supplied from the first and second laser drivers to the first and second semiconductor lasers, the absolute value of the wavelength change amount of the first and second semiconductor lasers can be made the same, and the distance and The measurement accuracy of speed can be improved.

Further, in the present invention, the determination result of the state determining means, among the candidate values of the speed or distance when the measurement object is assumed to be in the small displacement state and the candidate values of the speed or distance when the measurement object is assumed to be in the displacement state. The first and second laser drivers so as to maintain the continuity before and after the timing at which the wavelength change of the first and second semiconductor lasers is changed. By adjusting the amplitude of at least one of the drive currents supplied to the first and second semiconductor lasers from the first and second semiconductor lasers, the absolute value of the wavelength change amount of the first and second semiconductor lasers can be made the same, thereby improving the measurement accuracy of distance and speed. Can be.

On the other hand, the present invention can be applied to a technique for measuring the distance to the measurement target and the speed of the measurement target.

The present invention is a method for measuring a distance based on an interference signal between a wave emitted and a wave reflected from an object in sensing using wavelength modulation. Therefore, the present invention can be applied to optical interferometers other than the magnetic coupling type and interferometers other than light. In the case of using the magnetic coupling of the semiconductor laser in more detail, if the oscillation wavelength of the laser is changed while irradiating the laser light from the semiconductor laser to the measurement object, the oscillation wavelength changes from the minimum oscillation wavelength to the maximum oscillation wavelength (or The variation of the measured object, from the maximum oscillation wavelength to the minimum oscillation wavelength, is reflected in the number of MHPs. Therefore, by examining the number of MHPs when the oscillation wavelength is changed, the state of the measurement object can be detected. This is the basic principle of the interferometer.

[First Embodiment]

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. 1 is a block diagram showing the configuration of a distance / speedometer as a first embodiment of the present invention. 1 shows the light output of the first and second semiconductor lasers 1-1 and 1-2 and the semiconductor lasers 1-1 and 1-2 that emit laser light to the measurement target 11. Photodiodes 2-1 and 2-2, which are first and second light receivers, respectively, which convert into electrical signals, respectively, and collect light from semiconductor lasers 1-1 and 1-2, respectively. And the lenses 3-1 and 3-2 for converging the return light from the measurement target 11 and incident the semiconductor lasers 1-1 and 1-2, and the semiconductor lasers 1-1, The first and second laser drivers 4-1 and 4-2 which alternately repeat the first oscillation period in which the oscillation wavelength continuously increases and the second oscillation period in which the oscillation wavelength continuously decreases, Current-voltage conversion amplifiers 5-1 and 5-2 for converting the output currents of the diodes 2-1 and 2-2 into voltages and amplifying them respectively, and current-voltage conversion amplifiers 5-1 and 5-2. Filter circuits 6-1 and 6-2 for removing a carrier wave from an output voltage of A counting device 7 that counts the number of MHPs included in the output voltages of the terminator circuits 6-1 and 6-2, and an arithmetic device that calculates the distance between the measuring object 11 and the speed of the measuring object 11. (8), the display device 9 which displays the calculation result of the calculating device 8, and the laser driver 4-1, so that the amplitude of the drive current of the semiconductor lasers 1-1, 1-2 is appropriate. And an amplitude adjusting device 10 for controlling 4-2). The current-voltage conversion amplifiers 5-1 and 5-2, the filter circuits 6-1 and 6-2 and the counting device 7 constitute a counter 13.

Hereinafter, for ease of explanation, it is assumed that the semiconductor lasers 1-1, 1-2 are used without any type of mode hopping phenomenon (VCSEL type, DFB laser type).

The laser drivers 4-1 and 4-2 supply the semiconductor lasers 1-1 and 1-2 as an injection current, a triangular wave driving current which repeats the increase and decrease at a constant rate of change with respect to time. As a result, the semiconductor lasers 1-1 and 1-2 have a first oscillation period in which the oscillation wavelength continuously increases at a constant rate of change and a second oscillation period in which the oscillation wavelengths continuously decrease at a constant rate of change in proportion to the magnitude of the injection current. It is driven to repeat alternately. At this time, the laser drivers 4-1 and 4-2 supply the drive current so that the oscillation wavelengths of the semiconductor laser 1-1 and the semiconductor laser 1-2 are reversed. That is, the semiconductor laser 1-1 and the semiconductor lasers 1-2 have the same absolute value of the rate of change of the oscillation wavelength and the polarities of the rate of change are opposite to each other. Therefore, when the oscillation wavelength of the semiconductor laser 1-1 becomes the maximum value, the oscillation wavelength of the semiconductor laser 1-2 becomes the minimum value, and when the oscillation wavelength of the semiconductor laser 1-1 becomes the minimum value, The oscillation wavelength of the semiconductor laser 1-2 has a maximum value.

FIG. 2 is a diagram showing the time variation of the oscillation wavelength of the semiconductor lasers 1-1, 1-2. In Fig. 2, LD1 is the oscillation waveform of the semiconductor laser 1-1, LD2 is the oscillation waveform of the semiconductor laser 1-2, P1 is the first oscillation period, P2 is the second oscillation period, and λa is the oscillation in each period. The minimum value of the wavelength, λb is the maximum value of the oscillation wavelength in each period, and T is the period of the triangular wave. In this embodiment, the maximum value λb of the oscillation wavelength and the minimum value λa of the oscillation wavelength are always constant, respectively, and the difference thereof is also constant.

The laser light emitted from the semiconductor lasers 1-1 and 1-2 is collected by the lenses 3-1 and 3-2 and is incident on the measurement object 11. At this time, the laser beams of the semiconductor lasers 1-1 and 1-2 are emitted in parallel to each other and are incident on the measurement object 11. Light of the semiconductor lasers 1-1 and 1-2 reflected from the measurement target 11 is collected by the lenses 3-1 and 3-2, respectively, and is incident on the semiconductor lasers 1-1 and 1-2. do. On the other hand, condensing by the lenses 3-1 and 3-2 is not essential. The photodiodes 2-1 and 2-2 convert the light output of the semiconductor lasers 1-1 and 1-2 into currents, respectively. The current-voltage conversion amplifiers 5-1 and 5-2 convert the output currents of the photodiodes 2-1 and 2-2 into voltages and amplify them.

The filter circuits 6-1 and 6-2 have a function of extracting superimposed signals from modulated waves. 3A and 3B are diagrams schematically showing output voltage waveforms of the current-voltage conversion amplifiers 5-1 and 5-2, respectively, and (c) and (d) are filter circuits respectively. 6-1 and 6-2 are diagrams schematically showing output voltage waveforms. These figures show the semiconductor lasers 1-1 and 1-2 of FIG. 2 from the waveforms (modulation waves) of FIGS. 3A and 3B corresponding to the outputs of the photodiodes 2-1 and 2-2. The process of extracting the MHP waveform (overlapped wave) of FIGS. 3C and 3D by removing the oscillation waveform (carrier wave) of FIG.

The counting device 7 frequently counts the number of MHPs per unit time included in the output of the filter circuits 6-1 and 6-2 for each of the filter circuits 6-1 and 6-2. 4 is a block diagram showing an example of the configuration of the counter 7, and FIG. 5 is a flowchart showing the operation of the counter 7. The counting device 7 is composed of a changeover switch 70, period measuring units 71-1 and 71-2, and converting units 72-1 and 72-2.

First, the changeover switch 70 of the counting device 7 determines whether it is at the time of switching (step S100 in FIG. 5), and at the time of switching, the output of the filter circuits 6-1, 6-2 and the period measuring unit ( The connections of 71-1 and 71-2 are switched (step S101). The changeover of the changeover switch 70 is made every 1/2 hour of the triangular wave period T. That is, the changeover switch 70 connects the output of the filter circuit 6-1 to the input of the period measuring unit 71-1 in the first oscillation period P1, and outputs the filter circuit 6-2. Is connected to the period measuring unit 71-2. In the second oscillation period P2, the output of the filter circuit 6-2 is connected to the input of the period measuring unit 71-1. The output of 1) is connected to the period measuring unit 71-2 (step S101).

As a result, the period measuring unit 71-1 has the semiconductor laser 1-1 or the semiconductor laser 1 whose oscillation wavelength is increasing during the output of the filter circuit 6-1 or the filter circuit 6-2. The output corresponding to the side of -2) is always input, and the semiconductor measuring device 71-2 has a semiconductor laser (in which the oscillation wavelength is decreasing during the output of the filter circuit 6-1 or the filter circuit 6-2). The output corresponding to the 1-1) side or the semiconductor laser 1-2 is always input. On the other hand, whether the present point is the first oscillation period P1 or the second oscillation period P2 is notified from the laser drivers 4-1 and 4-2. The changeover switch 70 performs the changeover operation in accordance with the notification from the laser drivers 4-1 and 4-2.

The period measuring unit 71-1 generates a period (i.e., a period of MHP) of the rising edge of the input from the changeover switch 70 in the first counting period when a rising edge occurs at the input from the changeover switch 70. It measures every time (step S102 of FIG. 5). Similarly, the period measuring unit 71-2 sets the period (that is, the period of MHP) of the rising edge of the input from the switching switch 70 to the rising edge of the input from the switching switch 70 in the second counting period. It measures every time it arises (step S102).

Here, the first and second counting periods will be described with reference to FIG. 6. 6 (a) and 6 (b) schematically show output voltage waveforms of the current-voltage conversion amplifiers 5-1 and 5-2, respectively, and (c) and (d) respectively show filter circuits ( 6-1 and 6-2 are diagrams schematically showing output voltage waveforms. Pn1, Pn2, Pn3, Pn4, Pn5, Pn6, Pn7, Pn8 are first counting periods, Pm1, Pm2, Pm3, Pm4, Pm5, Pm6, Pm7, Pm8 are second counting periods, t0a, t1, t2, t0b, t3, t4, t0c, t5, t6, t0d, t7, t8 are the first counting periods Pn (Pn1, Pn2, Pn3, Pn4, Pn5, Pn6, Pn7, Pn8) and the second counting periods Pm (Pm1, Pm2, The start or end time of Pm3, Pm4, Pm5, Pm6, Pm7, and Pm8).

As shown in FIGS. 6C and 6D, the first counting period Pn (Pn1, Pn2, Pn3, Pn4, Pn5, Pn6, Pn7, Pn8) includes the filter circuit 6-1 or the filter circuit ( The output of 6-2) is set for the output corresponding to the semiconductor laser 1-1 side or the semiconductor laser 1-2 side in which the oscillation wavelength is increasing, and the second counting period Pm (Pm1, Pm2, Pm3) is set. , Pm4, Pm5, Pm6, Pm7, Pm8 are the semiconductor laser 1-1 side or semiconductor laser (1) in which the oscillation wavelength is reduced during the output of the filter circuit 6-1 or the filter circuit 6-2. It is set for the output corresponding to page 1-2).

The first counting period Pn and the second counting period Pm are shorter than the length of the first oscillation period P1 and the second oscillation period P2, that is, 1/2 of the triangle wave period T. desirable. In addition, it is necessary for the first counting period Pn and the second counting period Pm corresponding thereto to coincide with time. However, the first counting periods Pn may partially overlap each other, and the second counting periods Pm may partially overlap each other.

The gate signal GS input to the period measuring units 71-1 and 71-2 rises at the head of the first counting period Pn and the second counting period Pm, and the first counting period Pn and This signal falls at the end of the second counting period Pm. On the other hand, the first counting period Pn and the second counting period Pm are oscillated from a portion where the triangular wave driving current is maximized (a portion of switching from the oscillation period P1 to the oscillation period P2 or from the oscillation period P2). The period is set to the period except for the period (P1).

Subsequently, the converting unit 72-1 of the counting device 7 calculates the average value of the MHP periods measured by the period measuring unit 71-1 by the number of MHPs per unit time in the first counting period Pn (the oscillation wavelength is Number of interference waveforms toward the increasing semiconductor laser), and the conversion unit 72-2 converts the average value of the MHP periods measured by the period measurement unit 71-2 per unit time in the second counting period Pm. The number of MHPs is converted to the number Y (the number of interference waveforms toward the semiconductor laser whose oscillation wavelength is decreasing) (step S103 in Fig. 5). If the average period of the MHP is Ts and the frequency of the triangular wave is f, the number of MHPs per unit time can be calculated as {2 / (f × Ts)}. The unit time at this time is 1/2 time of the triangular wave period T.

The counting device 7 performs the above processing for each of the first and second counting periods Pn and Pm. Therefore, the number X of MHPs is calculated by the operations of the period measuring unit 71-1 and the converting unit 72-1, and the operation of the period measuring unit 71-2 and the converting unit 72-2 is calculated. The number Y of MHPs is calculated at the same time by calculating the number Y of MHPs.

Subsequently, the computing device 8 calculates the measurement target (based on the minimum oscillation wavelength lambda a, the maximum oscillation wavelength lambda b, and the number of MHPs (X, Y) of the semiconductor lasers 1-1, 1-2. The distance from 11) and the speed of the measurement target 11 are calculated. FIG. 7 is a block diagram showing an example of the configuration of the computing device 8, and FIG. 8 is a flowchart showing the operation of the computing device 8; The computing device 8 includes a storage unit 80 which stores the number (X, Y) of MHPs calculated by the counter 7 and the calculation result of the computing device 8, and the semiconductor lasers 1-1, Based on the minimum oscillation wavelength lambda a, the maximum oscillation wavelength lambda b, and the number of MHPs (X, Y) of 1-2), the distance candidate value with the measurement target 11 and the speed candidate with the measurement target 11 A distance / speed calculation unit 81 for calculating a value, a state judging unit 82 for determining a state of the measurement target 11 based on a calculation result of the distance / speed calculation unit 81, and a state judging unit ( Speed determination 83 for determining the speed of the measurement target based on the determination result of 82), and distance determination 84 for determining the distance to the measurement target based on the determination result of the status determination unit 82; Configured. The speed determiner 83 and the distance determiner 84 constitute a distance / speed determiner 86.

In the present embodiment, the state of the measurement object 11 is called either a microdisplacement state that satisfies a predetermined condition or a displacement state in which movement is larger than the microdisplacement state. When the average displacement of the measurement object 11 per counting period Pn and counting period Pm is V, the microdisplacement state satisfies (λb−λa) / λb> V / Lb. The displacement state is a state satisfying (λb−λa) / λb ≦ V / Lb. However, Lb is the distance from the measurement object 11 in the middle of the first and second counting periods Pn and Pm.

First, the storage unit 80 of the computing device 8 stores the numbers X, Y of the MHPs calculated by the counter 7 (step S201 in FIG. 8).

Subsequently, the distance / speed calculation unit 81 of the computing device 8 calculates the speed candidate value of the measurement target 11 and the distance candidate value between the measurement target 11 and stores the calculated value. ) (Step S202 of FIG. 8).

The distance / speed calculation unit 81 determines the number X (t) of the MHPs in the first counting period Pn and the number Y (t + 1) of the MHPs in the second counting period Pm + 1 at the next time. Based on the first candidate value Vα1 (t, t + 1) of the velocity at t + 1 from the time t, the number of MHPs Y (t) in the second counting period Pm, and the first counting period at the next time. From the time t based on the number X (t + 1) of the MHP at (Pn + 1), the second candidate value Vα2 (t, t + 1) of the velocity at t + 1, the number X (t) of the MHP, From time t based on Y (t + 1), the third candidate value Vβ3 (t, t + 1) of the velocity at t + 1, and time t based on the number of MHPs Y (t) and X (t + 1) The fourth candidate value Vβ4 (t, t + 1) of the velocity at t + 1 is calculated from the following equation and stored in the storage unit 80 (step S202).

Vα1 (t, t + 1) = (X (t) -Y (t + 1)) × λb / 4

Vα2 (t, t + 1) = (Y (t) -X (t + 1)) × λa / 4

Vβ3 (t, t + 1) = (X (t) + Y (t + 1)) × λb / 4

Vβ4 (t, t + 1) = (Y (t) + X (t + 1)) × λa / 4

Further, the distance / speed calculation unit 81 is based on the number of MHPs Y (t) in the second counting period Pm at the same time as the number X (t) of MHPs in the first counting period Pn. From time t-1, the fifth candidate value Vα5 (t) and the sixth candidate value Vβ6 (t) of the velocity at t are calculated in the following manner and stored in the storage unit 80 (step S202).

Vα5 (t) = (X (t) -Y (t)) × (λa + λb) / 8

Vβ6 (t) = (X (t) + Y (t)) × (λa + λb) / 8

In addition, the distance / speed calculating section 81 determines the number X (t) of the MHPs in the first counting period Pn and the number Y (t +) of the MHPs in the second counting period Pm + 1 at the next time. The first candidate value Lα1 (t, t + 1) of the distance at time t + 1 from time t based on 1), the number of MHPs Y (t) in the second counting period Pm, and the first time at the next time. The second candidate value Lα2 (t, t + 1) of the distance from time t to t + 1 based on the number X (t + 1) of the MHP in the counting period Pn + 1, and the number X (t) of the MHP ) Based on the third candidate value Lβ3 (t, t + 1) of the distance at time t + 1 from time t based on Y (t + 1) and the number of MHPs Y (t) and X (t + 1) The fourth candidate value Lβ4 (t, t + 1) of the distance at time t + 1 from time t is calculated as shown in the following equation and stored in the storage unit 80 (step S202).

Lα1 (t, t + 1) = λa × λb (X (t) + Y (t + 1)) / (4 × (λa-λb))

Lα2 (t, t + 1) = λa × λb (Y (t) + X (t + 1)) / (4 × (λa-λb))

Lβ3 (t, t + 1) = λa × λb (X (t) -Y (t + 1)) / (4 × (λa-λb))

Lβ4 (t, t + 1) = λa × λb (Y (t) -X (t + 1)) / (4 × (λa-λb))

Further, the distance / speed calculation unit 81 is based on the number of MHPs Y (t) in the second counting period Pm at the same time as the number X (t) of MHPs in the first counting period Pn. The fifth candidate value Lα5 (t) and the sixth candidate value Lβ6 (t) of the distance from the time t-1 to the measurement target 11 at t are calculated by the following equation and stored in the storage unit 80 ( Step S202).

Lα5 (t) = λa × λb (X (t) + Y (t)) / (4 × (λa-λb))

Lβ6 (t) = λa × λb (X (t) -Y (t)) / (4 × (λa-λb))

In Equations 2 to 13, candidate values Vα1 (t, t + 1), Vα2 (t, t + 1), Vα5 (t), Lα1 (t, t + 1), Lα2 (t, t + 1 ), Lα5 (t) is calculated by assuming that the measurement target 11 is in a microdisplacement state, and candidate values Vβ3 (t, t + 1), Vβ4 (t, t + 1), Vβ6 (t), Lβ3 (t, t + 1), Lβ4 (t, t + 1), and Lβ6 (t) are calculated by assuming that the measurement target 11 is in a displaced state.

Time t + 1 is the end time of the first counting period Pn + 1 and the second counting period Pm + 1, and time t is the first counting period Pn before Pn + 1 and Pm + 1. And the end time of the second counting period Pm, wherein time t-1 is the end of the first counting period Pn-1 and the second counting period Pm-1 two times before Pn + 1 and Pm + 1. It is time. X (t + 1) is the number of MHPs in the first counting period Pn + 1, X (t) is the number of MHPs in the first counting time Pn, and Y (t + 1) is the second counting The number of MHPs in the period Pm + 1, Y (t) is the number of MHPs in the second counting time Pm.

For example, if the current time is t + 1 = t2, the first counting period Pn + 1 is Pn2 in FIG. 6C, the first counting period Pn one time before is Pn1, and the second counting period is Pn1. The counting period Pm + 1 is Pm2 in FIG. 6 (d), and the second counting period Pm before the first time is Pm1. Further, if the current time is t + 1 = t3, the first counting period Pn + 1 is Pn3, the first counting period Pn one time before is Pn2, and the second counting period Pm + 1 is Pm3. , Before the second counting period Pm is Pm2. The computing device 8 performs the calculations of the equations (2) to (13) for each time the number of MHPs is calculated by the counter device (7).

Subsequently, the state determination unit 82 of the computing device 8 determines the state of the measurement target 11 using the calculation result of the equations (2) to (5) stored in the storage unit 80 (Fig. Step S203 of 8). The state determination unit 82 determines that Vα1 (t, t + 1) = Vα2 (t, t + 1), that is, when the calculation result of Equation 2 and Equation 3 is the same, the measurement target 11 is in a microdisplacement state. Is determined to be In addition, the state determination unit 82 determines that the measurement target 11 is displaced when Vβ3 (t, t + 1) = Vβ4 (t, t + 1), that is, the calculation results of the equations (4) and (5) are the same. Determine that it is in a state. On the other hand, the state judging unit 82 determines that these errors are the same when the error between the calculation result of Expression (2) and the calculation result of Expression (3) is within a predetermined error range. It can be determined similarly whether or not the calculation results of the equations (4) and (5) are the same.

The speed confirmation 83 of the calculating device 8 determines the absolute value of the speed of the measurement target 11 based on the determination result of the state determination unit 82 (step S204 in Fig. 8). In other words, when it is determined that the measurement target 11 is in the microdisplacement state, the speed confirmation 83 determines the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t stored in the storage unit 80. The average value of +1) is determined as the absolute value of the speed of the measurement target 11 at time t-1 from (t + 1) (step S204).

In addition, when it is determined that the measurement target 11 is in the displaced state, the speed confirmation 83 determines the speed candidate values Vβ3 (t, t + 1) and Vβ4 (t, t +) stored in the storage unit 80. The average value of 1) is determined as the absolute value of the speed of the measurement target 11 at t + 1 from time t-1 (step S204).

Thus, noise resistance can be improved by using the average value of the calculation result of Formula (2) and Formula 3, or the average value of the calculation result of Formula (4) and Formula (5). On the other hand, although noise resistance is inferior, the speed confirmation 83 determines the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) when it is determined that the measurement target 11 is in the microdisplacement state. Either of these may be determined as the absolute value of the speed of the measurement target 11, and when it is determined that the measurement target 11 is in the displacement state, the speed candidate values Vβ3 (t, t + 1) and Vβ4 (t , t + 1) may be determined as the absolute value of the velocity of the measurement target 11.

On the other hand, when it is determined that the measurement target 11 is in the microdisplacement state, the speed confirmation 83 measures the speed candidate value Vα5 (t) stored in the storage unit 80 at time t-1 from t. It may be set as the absolute value of the speed of the target 11 (step S204). In addition, when it is determined that the measurement target 11 is in the displacement state, the speed confirmation 83 determines the speed candidate value Vβ6 (t) stored in the storage unit 80 at the time t-1 from t. The speed absolute value of (11) may be determined (step S204).

Using the equation (6) or equation (7) can calculate the more accurate speed than when using the calculation results of equations (2) to (5).

Next, the speed confirmation 83 calculates the following equations (14) and (15) to determine the speed direction of the measurement target 11 (step S205 in Fig. 8).

ΣX = X (t) + X (t + 1)

ΣY = Y (t) + Y (t + 1)

The speed estimator 83 compares the magnitudes of? X in Equation 14 and? Y in Equation 15, and if? X is larger than? Y, it is determined that the measurement target 11 is closer to the distance / speed meter, and? Is large, it is determined that the measurement target 11 is far from the distance / speedometer.

On the other hand, instead of using the calculation results of the equations (2) to (5) in step S204, the speed confirmation 83 determines the absolute value of the speed by using the calculation result of the equation (6) or (7). When X (t) is larger than Y (t) by comparing the magnitudes of the numbers X (t) and Y (t), it is determined that the measurement target 11 is closer to the distance / speedometer, and Y is larger than X (t). If (t) is large, it is determined that the measurement target 11 is moving away from the distance / speedometer (step S205).

Subsequently, the distance determination 84 determines the distance to the measurement target 11 based on the determination result of the state determination unit 82 (step S206 in FIG. 8). That is, when it is determined that the measurement target 11 is in the microdisplacement state, the distance determiner 84 determines the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t stored in the storage unit 80. The average value of +1) is determined as the average distance from the time t-1 to the measurement target 11 at t + 1 (step S206).

Further, when it is determined that the measurement target 11 is in the displacement state, the distance confirmation 84 determines the distance candidate values Lβ3 (t, t + 1) and Lβ4 (t, t +) stored in the storage unit 80. The average value of 1) is determined as the average distance from the time t-1 to the measurement target 11 at t + 1 (step S206). On the other hand, although noise resistance is inferior, the distance determiner 84 determines that the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t + 1, when it is determined that the measurement target 11 is in the microdisplacement state. ) May be determined as the distance from the measurement object 11, and when it is determined that the measurement object 11 is in the displacement state, the distance candidate values Lβ3 (t, t + 1) and Lβ4 (t, Any one of t + 1) may be determined as a distance from the measurement target 11.

On the other hand, when it is determined that the measurement target 11 is in the microdisplacement state, the distance confirmation 84 measures the distance candidate value Lα5 (t) stored in the storage unit 80 at time t-1 from t. It may be set as the average distance from the object 11 (step S206). Further, when it is determined that the measurement target 11 is in the displacement state, the distance confirmation 84 determines the distance candidate value Lβ6 (t) stored in the storage unit 80 at the time t-1 from t. It may be set as the average distance from (11) (step S206).

Using the equation (12) or the equation (13) can calculate a more accurate distance than when using the calculation result of equations (8) to (11).

The arithmetic unit 8 performs the MHP by the counter 7 until the measurement end instruction (for example, "YES" in step S207 of FIG. 8) is received from the user, for example by the process of the above steps S201 to S206. Is executed at each time the number of times is calculated.

The display device 9 displays the distance to the measurement object 11 and the speed of the measurement object 11 calculated by the computing device 8 in real time.

On the other hand, the amplitude adjusting device 10 uses the determination result of the state determining unit 82 of the computing device 8, so that the amplitude of the triangular wave driving current of the semiconductor lasers 1-1, 1-2 is appropriate. Control the drivers 4-1 and 4-2.

In the distance / speed meter using the plurality of semiconductor lasers 1-1 and 1-2 as in the present embodiment, if there is a difference in the absolute value of the wavelength change amount of the semiconductor lasers 1-1 and 1-2, An error occurs. 9A to 9C are diagrams for explaining the change in the number (X, Y) of the MHPs according to the change of the wavelength change of the semiconductor lasers 1-1, 1-2. a) shows the time variation of the oscillation wavelength of the semiconductor lasers 1-1, 1-2, and FIG. 9B shows the same absolute value of the wavelength change amount of the semiconductor lasers 1-1, 1-2. The figure which shows the change of the number MHP of the case (X, Y), FIG.9 (c) shows the number of MHPs when there is a difference in the absolute value of the wavelength change amount of the semiconductor laser (1-1, 1-2) ( It is a figure which shows the change of X, Y). 9A to 9C, LD1 is the oscillation waveform of the semiconductor laser 1-1, LD2 is the oscillation waveform of the semiconductor laser 1-2, and X1 and X2 are the oscillation wavelengths respectively. The number of MHPs, Y1, and Y2 of the semiconductor lasers 1-1, 1-2 are the number of MHPs of the semiconductor lasers 1-1, 1-2 when the oscillation wavelength is decreasing, respectively.

When the absolute values of the wavelength change amounts of the semiconductor lasers 1-1 and 1-2 are the same, as shown in FIG. 9B, the oscillation wavelengths of the semiconductor lasers 1-1 and 1-2 decrease with increasing. The number of MHPs (X, Y) maintains continuity, respectively, before and after the timings SW1, SW2, and SW3 that change from decreasing or decreasing to increasing. If there is a difference in absolute values, as shown in Fig. 9C, the numbers (X, Y) of the MHPs each lose continuity.

Thus, the amplitude adjusting device 10 of the present embodiment has the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated by the distance / speed calculation unit 81 of the computing device 8. , Among the Vβ3 (t, t + 1) and Vβ4 (t, t + 1), the speed candidate 83 is judged not to be a real value from the determination result of the state determiner 82 and is not adopted. To adjust the amplitude. When it is determined that the measurement target 11 is exercising in the microdisplacement state, the speed candidate values that are not employed by the speed estimator 83 are Vβ3 (t, t + 1) and Vβ4 (t, t + 1). When it is determined that the measurement target 11 is moving in the displacement state, the speed candidate values not adopted by the speed estimator 83 are Vα1 (t, t + 1) and Vα2 (t, t + 1. ) Is the average value.

The amplitude adjusting device 10 has an average value of the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) or Vβ3 (t, t + 1) that are not employed by the speed determiner 83. The mean value of Vβ4 (t, t + 1) is the mean value of the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t + 1) adopted by judging that the distance determiner 84 is a real value, or Lβ3. The laser driver is approximately equal to the average value of (t, t + 1) and Lβ4 (t, t + 1) multiplied by the wavelength change rate (λb-λa) / λb of the semiconductor lasers 1-1, 1-2. Adjust the amplitude of the triangular wave driving current through (4-1, 4-2). At this time, the amplitude of both the driving current supplied from the laser driver 4-1 to the semiconductor laser 1-1 and the driving current supplied from the laser driver 4-2 to the semiconductor laser 1-2 may be adjusted. You may adjust either one. When it is determined that the measurement target 11 is in the microdisplacement state, the distance candidate value employed by the distance determiner 84 is an average value of Lα1 (t, t + 1) and Lα2 (t, t + 1), and is measured. When it is determined that the object 11 is in the displacement state, the distance candidate values employed by the distance determiner 84 are average values of Lβ3 (t, t + 1) and Lβ4 (t, t + 1).

FIG. 10 is a view for explaining the amplitude adjustment method of the triangular wave driving current supplied from the laser drivers 4-1 and 4-2 to the semiconductor lasers 1-1 and 1-2. In accordance with the instruction from the amplitude adjusting device 10, the laser drivers 4-1 and 4-2 set the maximum value of the drive current by a constant value (in the example of FIG. 10, by the semiconductor lasers 1-1 and 1-2). The amplitude AMP of the drive current is adjusted by increasing or decreasing the minimum value of the drive current while keeping the fixed upper limit CL of the specified drive current. In this way, an appropriate value can be set for the amplitude of the drive current.

As in this embodiment, by adjusting the amplitude of the triangular wave driving current, the absolute value of the wavelength change amount of the semiconductor lasers 1-1, 1-2 can be made the same, and the measurement error of distance and speed can be reduced.

On the other hand, when the speed determining unit 83 determines the absolute value of the speed using the calculation result of Equation 6 or 7, instead of using the calculation result of Equations 2 to 5, the amplitude adjusting device 10 ) Is a distance candidate value judged and adopted by the speed candidate value Vα5 (t) or Vβ6 (t) that the speed determiner 83 does not employ and judges that it is not a real value. The amplitude of the triangular wave drive current is adjusted so that Lα5 (t) or Lβ6 (t) is approximately equal to the product of the wavelength change ratios (λb-λa) / λb of the semiconductor lasers 1-1, 1-2. When it is determined that the measurement target 11 is moving in the microdisplacement state, the speed candidate value that is not employed by the speed checker 83 is Vβ6 (t), and it is determined that the measurement target 11 is moving in the displacement state. In this case, the speed candidate value not adopted by the speed determination 83 is V alpha 5 (t). When it is determined that the measurement target 11 is in the small displacement state, the distance candidate value adopted by the distance determination 84 is Lα5 (t), and when it is determined that the measurement target 11 is in the displacement state, the distance determination is made. The distance candidate value employed by the unit 84 is Lβ6 (t).

Further, the amplitude adjusting device 10 judges that the speed determination 83 is a true value from the determination result of the state determination unit 82, and employs the speed candidate values Vα1 (t, t + 1) and Vα2 (t, The average value of t + 1 or the average value of Vβ3 (t, t + 1) and Vβ4 (t, t + 1) are continuity before and after the timing at which the wavelength change of the semiconductor lasers 1-1, 1-2 is switched. The amplitude of the triangular wave driving current may be adjusted through the laser drivers 4-1 and 4-2 so as to maintain the shape. In addition, when the speed determiner 83 determines the absolute value of speed using the calculation result of Equation 6 or 7, instead of using the calculation result of Equations 2 to 5, the amplitude adjusting device 10 ) Is the timing candidate at which the wavelength candidates of the semiconductor lasers 1-1 and 1-2 are switched. The amplitude of the triangular wave drive current may be adjusted to maintain continuity before and after.

On the other hand, whether the present time is the first oscillation period P1 or the second oscillation period P2 is notified from the laser drivers 4-1 and 4-2, and the wavelength change of the semiconductor lasers 1-1 and 1-2 is made. The timing at which is switched is also notified from the laser drivers 4-1 and 4-2. The amplitude adjusting device 10 operates in accordance with the notification from the laser drivers 4-1 and 4-2.

Further, the amplitude adjusting device 10 judges that the distance determiner 84 is a real value from the determination result of the state determination unit 82, and adopts the distance candidate values Lα1 (t, t + 1) and Lα2 (t, The average value of t + 1 or the average value of Lβ3 (t, t + 1) and Lβ4 (t, t + 1) are continuity before and after the timing at which the wavelength change of the semiconductor lasers 1-1, 1-2 is switched. The amplitude of the triangular wave drive current may be adjusted so as to maintain the voltage. In addition, when the distance determiner 84 determines the distance by using the calculation result of Equation 12 or 13 instead of using the calculation result of Equations 8 to 11, the amplitude adjusting device 10 Before and after the timing at which the wavelength change of the semiconductor lasers 1-1 and 1-2 is switched, the distance candidate values Lα5 (t) or Lβ6 (t) which are determined by determining that the distance extension 84 is a real value are adopted. The amplitude of the triangular wave drive current may be adjusted to maintain continuity.

For example, the least square method may be used in order to have the continuity of the calculation result of the speed or distance before and after the timing at which the wavelength change of the semiconductor lasers 1-1 and 1-2 are switched. In addition, as shown in FIG. 11, the amplitude adjusting device 10 is a timing at which the wavelength change of the semiconductor lasers 1-1 and 1-2 is switched over the characteristic line VL connecting the calculation result of the speed (or distance). The amplitude of the triangular wave drive current may be adjusted so as to extend after (SW) and to include the calculation result VV of the initial speed (or distance) after the timing SW within the predetermined range ER for this extension line. .

As described above, in the present embodiment, the semiconductor lasers 1-1 and 1-2 alternately repeat the first oscillation period in which the oscillation wavelength is continuously increased and the second oscillation period in which the oscillation wavelength is continuously reduced. The number of MHPs included in the output signals of 2-1 and 2-2 is counted for each of the photodiode 2-1 and the photodiode 2-2, the counting result and the semiconductor laser 1-1, 1 The distance from the measurement target 11 and the speed of the measurement target 11 can be calculated from the minimum oscillation wavelength λa and the maximum oscillation wavelength λb of -2). As a result, in the present embodiment, a conventional self-coupled laser that (a) can be miniaturized, (b) a high-speed circuit is not required, (c) is resistant to disturbance light, and (d) does not cover the measurement object. While taking advantage of the measuring instrument, the measurement can be performed at the speed of the measurement target 11 as well as the distance to the measurement target 11. In addition, according to the present embodiment, it is possible to determine whether the measurement target 11 is performing a constant velocity movement or a motion other than the constant velocity movement.

In addition, in this embodiment, laser beams parallel to each other are simultaneously radiated to the measurement target 11 from semiconductor lasers 1-1 and 1-2 whose oscillation wavelengths are reversed. The first oscillation period and the second In the first counting period Pn, which is shorter than the oscillation period, the number X of MHPs included in the output of the photodiode 2-1 or the photodiode 2-2 is obtained, and the same time as the first counting period Pn is obtained. By calculating the number Y of MHPs included in the output of the photodiode 2-2 or the photodiode 2-1 in the second counting period Pm, it is shorter than the distance / speed meter described in Japanese Patent Laid-Open No. 2006-313080. You can measure distance and speed in time. In the distance / speed meter described in Japanese Patent Laid-Open No. 2006-313080, for example, at least three times of the first oscillation period t-1, the second oscillation period t, and the first oscillation period t + 1 are performed. The number of MHPs had to be counted over, but in this embodiment, for example, in the first counting period Pn1 and the second counting period Pm1, the number of MHPs (X, Y) is counted once, and the first counting is performed. In the counting period Pn2 and the second counting period Pm2, the number of MHPs (X, Y) is counted once, and the distance and speed can be obtained by counting the number of MHPs twice in total.

In this embodiment, the measurement accuracy of distance and speed can be improved by making the absolute value of the wavelength change amount of the semiconductor lasers 1-1 and 1-2 the same.

Second Embodiment

Next, a second embodiment of the present invention will be described. Also in this embodiment, since the overall configuration of the distance / speedometer is the same as that of the first embodiment, the description will be made using the symbols in FIG. 12 is a block diagram showing an example of the configuration of the counting device 7 in the second embodiment of the present invention, and FIG. 13 is a flowchart showing the operation of the counting device 7. The counting device 7 of the present embodiment includes a changeover switch 70a, determination units 73-1 and 73-2, logical AND operation units 74-1 and 74-2, and a counter 75 -1, 75-2, coefficient result correcting units 76-1, 76-2, storage unit 77, period sum calculating units 78-1, 78-2, and counting unit ( 79-1, 79-2).

14 is a block diagram showing an example of the configuration of the coefficient result correcting unit 76-1. The count result correcting unit 76-1 includes a period measuring unit 760, a frequency distribution preparing unit 761, a median value calculating unit 762, and a correction value calculating unit 763. Since the configuration of the count result correcting unit 76-2 is the same as that of the count result correcting unit 76-1, description thereof will be omitted.

15A to 15F are diagrams for explaining the operation of the counter 7 of the present embodiment, and FIG. 15A shows the output voltages of the filter circuits 6-1 and 6-2. 15. FIG. 15B schematically shows the shape, that is, the waveform of the MHP, FIG. 15B is a diagram showing the output of the determination units 73-1, 73-2 corresponding to FIG. 15A, FIG. c) is a figure which shows the gate signal GS input to the counting device 7, FIG. 15 (d) is a figure which shows the counting result of the counter 75-1 corresponding to FIG. 15 (b), FIG. 15E shows a clock signal CLK input to the counting device 7, and FIG. 15F shows a cycle of the count result correcting unit 76-1 corresponding to FIG. 15B. It is a figure which shows the measurement result of the measuring part 760. 15A to 15F, the oscillation wavelength of the semiconductor laser 1-1 increases and the oscillation wavelength of the semiconductor laser 1-2 reduces for the first oscillation period P1. Indicates.

First, the changeover switch 70a of the counting device 7 determines whether it is at the time of switching (step S300 in FIG. 13), and at the time of switching, the output of the filter circuits 6-1 and 6-2 and the determination unit 73. -1, 73-2 are switched (step S301). The changeover of the changeover switch 70a occurs every 1/2 hour of the period T of the triangular wave. That is, the changeover switch 70a connects the output of the filter circuit 6-1 to the input of the determination unit 73-1 in the first oscillation period P1, and outputs the output of the filter circuit 6-2. Connected to the determination unit 73-2, and in the second oscillation period P2, the output of the filter circuit 6-2 is connected to the input of the determination unit 73-1, The output is connected to the determination unit 73-2 (step S301).

As a result, the determination unit 73-1 has the semiconductor laser 1-1 or the semiconductor laser 1-1 on which the oscillation wavelength is increasing among the outputs of the filter circuit 6-1 or the filter circuit 6-2. The output corresponding to 2) is always input, and the semiconductor laser 1 of the side in which the oscillation wavelength is decreasing among the outputs of the filter circuit 6-1 or the filter circuit 6-2 is input to the determination unit 73-2. -1 or an output corresponding to the semiconductor laser 1-2 is always input. On the other hand, whether the present point is the first oscillation period P1 or the second oscillation period P2 is notified from the laser drivers 4-1 and 4-2. The changeover switch 70a performs the changeover operation in accordance with the notification from the laser drivers 4-1 and 4-2.

The judging unit 73-1 of the counting device 7 determines whether the output voltage of the filter circuit 6-1 or the filter circuit 6-2 shown in Fig. 15A is high level (H) or low level. It is determined whether or not (L), and the determination result as shown in Fig. 15B is output. At this time, the determination unit 73-1 determines that the filter circuit 6-1 is high level when the output voltage of the filter circuit 6-1 or the filter circuit 6-2 rises and becomes equal to or higher than the threshold value TH1. 6-1) or the filter circuit 6-1 or the filter circuit 6 by determining that the output voltage of the filter circuit 6-2 is low when the output voltage falls below the threshold value TH2 (TH2 < TH1). The output of -2) is binarized (step S302 in Fig. 13). Similarly, the determination unit 73-2 binarizes the output of the filter circuit 6-2 or the filter circuit 6-1 (step S302).

The AND 74-1 outputs the output of the determination unit 73-1 and the logical product operation result of the gate signal GS as shown in FIG. 15C, and the counter 75-1 outputs the result of FIG. As shown in d), the output rise of the AND 74-1 is counted (step S303 in Fig. 13). Similarly, the AND 74-2 outputs the result of the AND operation of the output of the determination unit 73-2 and the gate signal GS, and the counter 75-2 outputs the output rise of the AND 74-2. It counts (step S303). Here, the gate signal GS rises at the beginning of the first counting period Pn and the second counting period Pm, and descends at the end of the first counting period Pn and the second counting period Pm. to be. Accordingly, the counters 75-1 and 75-2 are used to determine the number of rising edges (ie, rising edges of the MHP) of the outputs of the ANDs 74-1 and 74-2 during the first and second counting periods Pn and Pm. Is counted). Definition of the first counting period Pn and the second counting period Pm is as described with reference to FIGS. 6A to 6D.

On the other hand, the period measuring unit 760 of the counting result correcting unit 76-1 ANDs the period of the rising edge of the output of the AND 74-1 in the first counting period Pn (that is, the period of the MHP). It measures every time a rising edge occurs in the output of 74-1 (step S304 of FIG. 13). At this time, the period measuring unit 760 measures the period of the MHP with the period of the clock signal CLK shown in FIG. 15E as one unit. In the example of FIG. 15F, the period measuring unit 760 sequentially measures Tα, Tβ, and Tγ as the period of the MHP. As apparent from Figs. 15E and 15F, the periods Tα, Tβ, and Tγ are 5 clocks, 4 clocks, and 2 clocks, respectively. The frequency of the clock signal CLK is sufficiently high with respect to the highest frequency acquired by the MHP.

Similarly, the period measuring unit 760 of the counting result correcting unit 76-2 ANDs the period of the rising edge of the output of the AND 74-2 (that is, the period of MHP) in the second counting period Pm. Every time a rising edge occurs in the output of 74-2, it measures (step S304).

The storage unit 77 stores the counting results of the counters 75-1 and 75-2 and the measurement results of the period measuring unit 760 of each of the counting result correcting units 76-1 and 76-2.

After the gate signal GS falls and the first counting period Pn ends, the frequency distribution preparing unit 761 of the counting result correcting unit 76-1 counts the counting results stored in the storage unit 77. The frequency distribution of the period of MHP in 1st counting period Pn is created from the measurement result of the period measuring part 760 of the correction | amendment part 76-1 (step S305 of FIG. 13). Similarly, after the second counting period Pm is finished, the frequency distribution preparing unit 761 of the counting result correcting unit 76-2 is configured to determine the period measuring unit 760 of the counting result correcting unit 76-2. From the measurement result, the frequency distribution of the period of MHP in 2nd counting period Pm is created (step S305). On the other hand, when n is small, the frequency for obtaining the median value is small, and the precision for obtaining the median value is inferior. Therefore, when the median distribution for obtaining the median value of the period of MHP during the first counting period Pn is also used, Resistant to continuous noise.

Subsequently, the median value calculation unit 762 of the count result correcting unit 76-1 calculates the first count period Pn from the frequency distribution created by the frequency distribution preparing unit 761 of the count result correcting unit 76-1. The median T0 of the period of the MHP is calculated (step S306 in FIG. 13). Similarly, the median value calculating part 762 of the counting result correcting unit 76-2 calculates the second counting period Pm from the frequency distribution created by the counting distribution preparing unit 761 of the counting result correcting unit 76-2. The median value T0 of the period of the MHP in the process is calculated (step S306).

The correction value calculating unit 763 of the coefficient result correcting unit 76-1 is configured in the first counting period Pn from the frequency distribution created by the frequency distribution preparing unit 761 of the counting result correcting unit 76-1. The sum Ns of the degrees of the class less than 0.5 times the median value T0 of the period, and the total Nw of the degrees of the class more than 1.5 times the median value T0 of the period during the first counting period Pn, are obtained. The counting result of (75-1) is corrected as in the following equation (16) (step S307 of Fig. 13).

N ′ = N + Nw-Ns

In Equation 16, N is the number of MHPs that are counting results of the counter 75-1, and N 'is counting result after correction.

Similarly, the correction value calculation unit 763 of the coefficient result correcting unit 76-2 calculates the second counting period Pm from the frequency distribution created by the frequency distribution preparing unit 761 of the counting result correcting unit 76-2. The sum Ns of the degrees of the class less than 0.5 times the median value T0 of the period in the cycle) and the total Nw of the degrees of the class more than 1.5 times the median value T0 of the period in the second counting period Pm are obtained. The counting result of the counter 75-2 is corrected as in Equation 16 (step S307).

16 shows an example of the frequency distribution of the period of the MHP. In FIG. 16, Ts is a class value 0.5 times the median value T0 of the period of the MHP, and Tw is a class value 1.5 times the median value T0. It goes without saying that the rank in Fig. 16 is a representative value of the period of the MHP. In addition, in FIG. 16, the frequency distribution between the median value T0 and Ts and between the median value T0 and Tw is abbreviate | omitted in order to simplify description.

17A and 17B are diagrams for explaining the principle of correction of the counting results of the counters 75-1 and 75-2, and FIG. 17A shows the output of the filter circuit 6-1. FIG. 17B is a diagram schematically showing the waveform of the voltage, that is, the waveform of the MHP. FIG. 17B is a diagram showing the counting result of the counter 75-1 corresponding to FIG.

Originally, the period of the MHP varies depending on the distance from the measurement object 11, but if the distance from the measurement object 11 does not change, the MHP appears in the same period. However, due to the noise, missing waveforms occur in the MHP waveform or waveforms that should not be counted as signals generate errors in the number of MHPs.

When a signal is lost, the period Tw of the MHP at the missing portion is about twice the original period. As a result, when the period of the MHP is about twice or more than the median value T0, it can be determined that a missing signal has occurred in the signal. Therefore, by seeing the total number Nw of the frequencies of the class Tw or more as the number of times the signal is missing, the signal missing can be corrected by adding this Nw to the count result N of the counter 75-1. .

In addition, the period Ts of the MHP at the portion where the noise is counted becomes about 0.5 times the original period. As a result, when the period of the MHP is about 0.5 times or less of the median value T0, it can be determined that the signal is excessively counted. Thus, by counting the total number Ns of the frequency of the rank below the period Ts as the number of times the signal is excessively counted, and subtracting this Ns from the count result N of the counter 75-1, the wrong counted noise can be corrected. Can be.

The above is the principle of correction of the coefficient result shown in equation (16). The counting result of the counter 75-2 can also be corrected on the same principle. In the present embodiment, Ts is 0.5 times the median value T0 of the period, and Tw is 1.5 times the value of 2 times the median value T0. Let's do it.

Subsequently, the period sum calculator 78-1 of the counting device 7 calculates the first coefficient from the measurement result of the period measuring unit 760 of the count result correcting unit 76-1 stored in the storage unit 77. The sum Sum of the periods of the MHPs in the period Pn is calculated (step S308 in FIG. 13). Similarly, the period sum calculating unit 78-2 calculates the sum Sum of the periods of the MHPs in the second counting period Pm from the measurement result of the period measuring unit 760 of the counting result correcting unit 76-2. It calculates (step S308).

The number calculating unit 79-1 of the counting device 7 calculates the number X of MHPs per unit time (the number of interference waveforms of the semiconductor laser of which the oscillation wavelength is increasing) during the first counting period Pn, The number calculating unit 79-2 calculates the number Y of the MHPs per unit time (the number of the interference waveforms of the semiconductor laser of which the oscillation wavelength is decreasing) during the second counting period Pm (step S309 of Fig. 13). . The count calculation unit 79-1 sends the count result N 'after correction calculated by the correction value calculation unit 763 of the count result correction unit 76-1 to the period sum calculation unit 78-1. The number X of MHPs per unit time in the first counting period Pn is calculated by dividing by the sum Sum of the periods of the MHPs in the first counting period.

X = N '/ Sum

Similarly, the number calculating unit 79-2 cycles the count result N ′ after the correction calculated by the correction value calculating unit 763 of the counting result correcting unit 76-2. The number Y of MHPs per unit time in the second counting period Pm is calculated by dividing by the sum Sum of the periods of the MHPs in the second counting period calculated by "

The counting device 7 performs the above processing for each of the first and second counting periods Pn and Pm. Therefore, the determination unit 73-1, AND 74-1, counter 75-1, count result correcting unit 76-1, storage unit 77, period sum calculating unit 78-1, and The number X of MHPs is calculated by the operation of the number calculating unit 79-1, and the determining unit 73-2, AND 74-2, counter 75-2, counting result correcting unit 76- 2) The number of MHPs X and Y are simultaneously obtained in such a manner that the number Y of MHPs is calculated by the operations of the storage unit 77, the period sum calculating unit 78-2, and the number calculating unit 79-2. .

Configurations other than the counting device 7 are the same as in the first embodiment. In this embodiment, the period of the MHP in the counting period is measured, the frequency distribution of the period of the MHP in the counting period is created from this measurement result, the median value of the period of the MHP is calculated from the frequency distribution, and 0.5 times the median value from the frequency distribution. The counting error of the MHP can be corrected by obtaining the sum Ns of the following ranks (Ns) and the sum Nw of the ranks 1.5 times or more the median, and correcting the counter counting results based on these sums Ns and Nw. Therefore, compared with the first embodiment, the measurement accuracy of the distance and the speed can be improved.

Next, the reason why the median of the frequency distribution of the cycle is used as the reference period of the MHP in this embodiment, and the reason why the threshold value of the cycle when obtaining the frequency Nw is 1.5 times the median will be explained.

First, since the noise is counted incorrectly, correction of the counting result when the period of the MHP is divided into two will be described. When the oscillation wavelength change of the semiconductor laser is linear, the period of the MHP is normally distributed centering on T0 obtained by dividing the counting period by the number N of the MHP (FIG. 18).

Next, the period of MHP divided into two by noise is considered. As a result of excessively counting the noise, the period of the MHP divided into two is divided into two at an irregular rate. Since the period before the division is a normal distribution centering on T0, the frequency distribution is symmetric about 0.5T0 (Fig. 19). A).

With respect to the frequency distribution of the period of the MHP containing this noise, assuming that k% of the MHP is divided into two periods by noise, the average value and the median value of the period of the MHP are calculated.

The sum of all the periods is the counting period, but does not change, but if the k% of the MHP is divided into two periods by noise, the integral value of the frequency becomes (1 + k [%]) N, so the average value of the period of the MHP Becomes (1 / (1 + k [%])) T0.

On the other hand, when ignoring the overlapping portion of the normal distribution in the noise distribution, since the cumulative frequency of the divided noise is twice the frequency contained in the rank between the median value and T0, the median value of the MHP period is shown in FIG. The area of b becomes twice the area of a.

The internal ratio of the two-sided values between the average value of the normal distribution and the ασ in Excel (registered trademark) of Microsoft's software is expressed as '(1- (1-NORMSDIST (α)) * 2) * 100 [%]'. There is a function called (), and using this function, the median value of the MHP period can be expressed by the following equation.

(1- (1-NORMSDIST ((median-T0) / σ)) * 2) * (100-k) / 2 = k [%]

Based on the above, if the standard deviation (σ) is set to 0.02T0, and the average value (T0 ') and the median value (T0') of the MHP cycle are calculated when 10% of the MHP is divided into two periods due to noise, , Becomes

T0 ′ = (1 / (1 + 0.1)) T0 = 0.91T0

T0 ′ = 0.995T0

In addition, it is assumed here that both an average value and a median value are represented by T0 '. The counter value (the integral value of the frequency) is 1.1N, and the count error is 10%.

Here, the probability of the acquisition period of two cycles T1 and T2 (where T1? T2) after the MHP of a period Ta is divided into two is considered. Assuming that noise occurs irregularly, as shown in Fig. 21, T2 acquires a value of 0 &lt; T2 &lt; Similarly, T1 acquires the value of T / 2≤T1 <Ta with the same probability. In FIG. 21, both the area of the acquisition probability distribution of T1 and the area of the acquisition probability distribution of T2 are 1.

Since the period Ta is a normal distribution centering on T0, when Ta is regarded as a set, the frequency distribution of the probability of acquisition of T2 is equal to the cumulative frequency distribution of the normal distribution with an average value of 0.5T0 and a standard deviation of 0.5σ. The same shape.

As shown in Fig. 22, the frequency distribution of the acquisition probability of T1 is a cumulative frequency distribution of a normal distribution having an average value of 0.5T0 and a standard deviation of 0.5σ, and a cumulative frequency distribution of a normal distribution having an average value of T0 and a standard deviation of σ. The overlapping shape becomes. Here, the number of T1 and T2 is equal to the number k [%] · N of the MHPs in which the period is divided into two.

If the number k [%] · N of the MHP whose period is divided by the noise can be counted, the number N of the MHPs can be derived using Equation 21 below.

N = N'-k [%] N

As shown in Fig. 23, if Tb can be set such that the number Ns of MHPs having a period of Tb or less is equal to the number (k [%]. N) of two divided MHPs, the MHP having a period of Tb or less By counting the number Ns, it is possible to indirectly count the number (k [%] · N) of the MHP whose cycle is divided into two.

In Fig. 23, when the frequency of the period T2 of the MHP having a period of Tb or more (c in Fig. 23) and the frequency of the period T1 of the MHP having a period less than Tb (d in Fig. 23), Tb The number of MHPs having the following period is equal to the number of T2, that is, the number Ns (= k [%] · N) of MHPs in which the period is divided into two. As a result, the number N of MHPs can be expressed by the following equation.

N = N'-k [%] N = N'-Ns

Since the frequencies of T1 and T2 are symmetrical at 0.5Ta, when 0.5Ta is determined as the threshold, the frequency Ns (= k [%] · N) of the MHP whose cycle is divided into two can be accurately counted. .

Subsequently, by counting the number of MHPs having periods of 0.5T0 or less, the number (k [%]. N) of MHPs divided into two periods can be indirectly counted. The frequency distribution of the periods of MHP containing noise (Fig. 19 cannot calculate T0. As shown in the frequency distribution of FIG. 19, the mother group of the MHP is ideal as the mode is equal to T0, and when the parameter is large, the mode can be used as T0 '.

Here, the coefficient of the number (k [%]. N) of MHP using an average value or median value T0 'is described. When T0 '= yT0 is substituted and Ns is obtained by substituting T0' instead of T0, the frequency Ns 'of cycles smaller than 0.5T0' which is determined as the number of MHPs divided into two periods is y · k [%]. It becomes N (FIG. 24).

When the average value or median value T0 'is used, the count value Nt after correction is expressed as follows.

Nt = N'-Ns' = (1 + k [%]) N-yk [%] N = (1 + (1-y) k [%]) N = N + (1-y) k [%] N

On the other hand, (1-y) k [%]) N, which is an error after correction, is the frequency of part e in FIG.

Here, an example of correcting the counting result of the counters 75-1 and 75-2 using the average value or the median value T0 'will be described.

If the standard deviation is sigma = 0.02T0 and 10% of the MHP is divided into two periods due to noise (the coefficient result is 10% error), the mean value (T0 ') of the MHP period is 0.91T0 and the median value (T0). ′) Is 0.9949T0, so that y when the average value T0 'is used is 0.91 and y when the median value T0' is used is 0.9949, and the coefficient result N 'after correction is calculated as follows.

N '= (1 + 0.1 (1-0.91)) N = 1.009 N

N '= (1 + 0.1 (1-0.995)) N = 1.0005 N

Equation (24) shows the counting result (N ') after correction in the case of using the average value (T0'), and (25) shows the counting result (N ') after correction in the case of using the median value (T0'). The error in the counting result N 'when the average value T0' is used is 0.9%, and the error in the counting result N 'when the median value T0' is used is 0.05%.

Subsequently, if the standard deviation is sigma = 0.05T0 and 20% of the MHP is divided into two periods due to noise (the coefficient result is 20% error), the mean value (T0 ') of the MHP period is 0.83T0, the median value. Since (T0 ') is 0.9682T0, y when the average value T0' is used is 0.83, y when the median value T0 'is used is 0.968, and the coefficient result N' after correction is calculated as follows. .

N ′ = (1 + 0.2 (1-0.83)) N = 1.034 N

N '= (1 + 0.2 (1-0.968)) N = 1.0064 N

Equation 26 shows the counting result N 'after correction when the average value T0' is used, and Equation 27 shows the counting result N 'after correction when the median value T0' is used. The error in the counting result N 'when the average value T0' is used is 3.4%, and the error in the counting result N 'when the median value T0' is used is 0.64%.

As described above, it can be seen that by correcting the counting result N using the median value of the period of the MHP, the error of the counting result N 'after the correction can be reduced.

Next, correction | amendment of the count result in the case where a missing | missing arises in the waveform of MHP is demonstrated. The period of MHP when the strength of MHP is small and a defect occurs at the time of counting is normally a normal distribution centering on T0 of MHP, so that a normal distribution (f in Fig. 26) having an average value of 2T0 and a standard deviation of 2σ is shown. do. If the MHP of j [%] is missing, the frequency of the period of the MHP which has doubled due to the missing is Nw (= j [%] · N). Incidentally, the frequency of the period of approximately T0 after the decrease due to the missing time at the time of counting is g shown in FIG. 26, and the decrease in frequency shown by h in FIG. 26 is 2Nw (= 2j [%]). Therefore, the original number (N ') of MHPs when no missing MHP occurs at the time of counting can be expressed by the following equation.

N ′ = N + j [%] = N + Nw

Next, the threshold value of the period when counting Nw for correcting the counting result is considered. Here, suppose that p [%] is divided into two by the noise in the frequency Nw of the period of the MHP where the period is doubled due to the lack of counting. The frequency of the period of two divided MHPs among missing MHPs is Nw '(= j.p [%]. N). The frequency distribution of the cycle of MHP divided into two is as shown in FIG. 27. If the threshold of the period assumed to be Nw is 1.5T0, the frequency of the MHP cycle whose cycle is 0.5T0 or less is 0.5Nw '(= 0.5p [%] Nw), and the cycle of the MHP whose cycle is 0.5T0 to 1.5T0. The frequency of is Nw '(= p [%] · Nw), and the frequency of the cycle of MHP having a period of 1.5T0 or more is 0.5Nw' (= 0.5p [%] · Nw).

Therefore, the frequency distribution of all MHP periods is as shown in FIG. 28. When the threshold value of Ns is 0.5T0 and the threshold value of Nw is 1.5T0, the counting result N can be expressed by the following equation.

N = (N′-2Nw) + (Nw-Nw ′) + 2Nw ′ = N′-Nw + Nw ′

The result corrected from the equation (29) is as follows, and it can be seen that the original number of MHPs (N ') is calculated in the case where a missing MHP does not occur at the time of counting.

N-0.5Nw ′ + (0.5Nw ′ + (Nw-Nw ′)) = (N-Nw + Nw ′) + (0.5Nw ′ + (Nw-Nw ′)) = N ′

As described above, it can be seen that the counting result N can be corrected by setting the threshold value of the period when the frequency Nw is obtained to be 1.5 times the median value. On the other hand, similarly to the case where the period of the MHP is divided into two by noise, since the correction is made using the median instead of T0, the same error occurs.

In the above description, when the period of the MHP is divided into two when the noise is excessively counted and the period of the MHP is doubled due to the lack of counting, these cases are generated independently. If they are expressed by one frequency distribution, they are as shown in FIG. If the threshold of Ns is 0.5T0 and the threshold of Nw is 1.5T0, the counting result N can be expressed by the following equation.

N = (N′-2Nw-Ns) + (Nw-Nw ′) + 2Nw ′ + 2Ns = N′-Nw + Nw ′ + Ns

The result corrected from the equation (31) is as follows, and it can be seen that the original number (N ') of the original MHPs when no missing or excess coefficient occurs at the time of counting.

N- {0.5Nw ′ + Ns} + {0.5Nw ′ + (Nw-Nw ′)} = {N-Nw + Nw ′ + Ns}-{0.5Nw ′ + Ns} + {0.5Nw ′ + (Nw- Nw ′)} = N ′

On the other hand, in the present embodiment, the missing correction of the MHP has been described for the case where the period of the MHP becomes about twice the original period by one missing, but the present invention is applied even when two or more missing occurrences occur in succession. can do. In the case where two MHPs are dropped in succession, it is considered that three MHPs of one cycle are three times the median. In this case, if the frequency of a class which is about three times or more of the median of a period is calculated | required, and this frequency is doubled, the missing of MHP can be correct | amended. When generalizing such a method, Equation 33 below may be used instead of Equation 16.

N '= N + Nw1 + Nw2 + Nw3 +... -Ns

Nw1 is the sum of the counts of the classes at least 1.5 times the median of the cycle, Nw2 is the sum of the counts of the classes at least 2.5 times the median of the cycle, and Nw3 is the sum of the counts of the classes at least about 3.5 times the median of the cycle.

Third Embodiment

Next, a third embodiment of the present invention will be described. In the second embodiment, the number of MHPs is obtained in the first counting period Pn and the second counting period Pm of fixed length, and the first counting period Pn and the second counting period Pm are variable lengths. You may make it. Also in this embodiment, since the configuration of the distance / speedometer is the same as that of the first embodiment, the description will be made using the symbols of FIG.

30 is a block diagram showing an example of the configuration of the counter 7 of the present embodiment, and FIG. 31 is a flowchart showing the operation of the counter 7. The counting device 7 of this embodiment includes a changeover switch 70a, period measuring units 71a-1 and 71a-2, determination units 73-1 and 73-2, and counting result correcting unit 76a. -1, 76a-2, a storage unit 77, a cycle sum calculating unit 78-1, 78-2, and a number calculating unit 79-1, 79-2.

32 is a block diagram showing an example of the configuration of the count result correcting unit 76a-1. The count result correcting unit 76a-1 includes a frequency distribution preparing unit 761a, a median value calculating unit 762a, and a correction value calculating unit 763a. Since the configuration of the count result correcting unit 76a-2 is the same as that of the count result correcting unit 76a-1, the description is omitted.

First, the operation of the changeover switch 70a is the same as the steps S300 and S301 of FIG. 13 (steps S400 and S401 of FIG. 31), and the operations of the determination units 73-1 and 73-2 are different from the steps S302 of FIG. 13. (Step S402 of Fig. 31).

The period measuring unit 71a-1 applies a predetermined number of NHP periods (N is a natural number of two or more) at the output of the determination unit 73-1 shown in Fig. 15B to each of these MHPs. It measures (step S403 of FIG. 31). Similarly, the period measuring unit 71a-2 measures the period of the predetermined number N MHPs at the output of the determining unit 73-2 for each of these MHPs (step S403). At this time, the period measuring units 71a-1 and 71a-2 measure the period of the MHP with the period of the clock signal CLK as one unit. The storage unit 77 stores the measurement results of the period measuring units 71a-1 and 71a-2.

After the measurement of the period measuring unit 71a-1 is finished, the frequency distribution preparing unit 761a of the counting result correcting unit 76a-1 is the measurement result of the period measuring unit 71a-1 stored in the storage unit 77. The frequency distribution of the period of MHP is created from (step S404 of FIG. 31). Similarly, after the end of the measurement of the period measuring unit 71a-2, the frequency distribution preparing unit 761a of the counting result correcting unit 76a-2 calculates the frequency of the MHP period from the measurement result of the period measuring unit 71a-2. The distribution is created (step S404).

Subsequently, the median calculating unit 762a of the counting result correcting unit 76a-1 calculates the median value T0 of the period of the MHP from the frequency distribution created by the frequency distribution preparing unit 761a of the counting result correcting unit 76a-1. It calculates (step S405 of FIG. 31). Similarly, the median value calculator 762a of the coefficient result corrector 76a-2 calculates the median value T0 of the period of the MHP from the frequency distribution created by the frequency distribution preparer 761a of the coefficient result corrector 76a-2. It calculates (step S405).

The correction value calculator 763a of the count result correcting unit 76a-1 calculates the count result correcting unit 76a-1 from the frequency distribution created by the frequency distribution producing unit 761a of the count result correcting unit 76a-1. The sum Ns of the degrees of the class which is 0.5 times or less of the median value T0 of the period calculated by the median value calculating unit 762a of), and the sum of the frequencies Nw that are 1.5 times or more the median value T0 of this period. Is obtained, and the predetermined number N is corrected as in Equation 16 (step S406 in Fig. 31). Similarly, the correction value calculator 763a of the count result correcting unit 76a-2 uses the count result correcting unit 76a from the frequency distribution created by the frequency distribution preparing unit 761a of the count result correcting unit 76a-2. The sum (Ns) of the degrees of the class which is 0.5 times or less of the median value T0 of the period calculated by the median value calculating unit 762a of -2), and the sum of the frequencies of the class that is 1.5 times or more of the median value T0 of this period ( Nw) is obtained, and the predetermined number N is corrected as in Equation 16 (step S406).

Subsequently, the period sum calculating unit 78-1 calculates the sum Sum of the periods of the MHPs from the measurement result of the period measuring unit 71a-1 stored in the storage unit 77 (step S407 in FIG. 31). ). Similarly, the period sum calculator 78-2 calculates the sum Sum of the periods of the MHP from the measurement result of the period measuring unit 71a-2 (step S407).

The number calculating unit 79-1 supplies the resultant counting result N 'calculated by the correction value calculating unit 763a of the counting result correcting unit 76a-1 to the period sum calculating unit 78-1. The number X of MHPs per unit time in the first counting period Pn is calculated by dividing by the sum Sum of the periods of the MHPs calculated by (step S408 in FIG. 31). Similarly, the number calculating unit 79-2 cycles the count result N ′ after the correction calculated by the correction value calculating unit 763a of the counting result correcting unit 76a-2 and the period sum calculating unit 78-2. The number Y of MHPs per unit time in the second counting period Pm is calculated by dividing by the sum Sum of the periods of the MHPs calculated by &quot;) (step S408).

The counting device 7 performs the above processing for each of the first and second counting periods Pn and Pm. The number X and Y of MHPs are simultaneously calculated as in the first and second embodiments. As described above, in the present embodiment, the first counting period Pn and the second counting period Pm become variable lengths. That is, the sum of the periods of the MHPs calculated by the period sum calculation unit 78-1 corresponds to the length of the first counting period Pn, and the sum of the periods of the MHPs calculated by the period sum calculation unit 78-2. It corresponds to the length of this 2nd counting period Pm. The value corresponding to the count result N of the counters 75-1 and 75-2 of the second embodiment is a fixed value of a predetermined number N in this embodiment.

The rest of the configuration is the same as in the second embodiment. In the second embodiment, since the first counting period Pn and the second counting period Pm are fixed lengths, the sum of the periods of the MHPs calculated by the period sum calculating unit 78-1 is the first counting period Pn. ), And the total sum of the periods of the MHPs calculated by the period sum calculating unit 78-2 may not coincide with the length of the second counting period Pm. For this reason, in the second embodiment, there is a possibility that a measurement error occurs in the number (n, m) of the MHPs obtained by the counter 7, and a measurement error occurs in the distance and speed.

In contrast, in the present embodiment, the sum of the periods of the MHPs calculated by the period sum calculators 78-1 and 78-2 is equal to the length of the first count period Pn and the second count period Pm. Therefore, the measurement error of the number (n, m) of MHPs can be reduced. Therefore, according to this embodiment, not only the same effect as in the second embodiment can be obtained, but also the measurement accuracy of distance and speed can be further improved.

[Example 4]

Next, a fourth embodiment of the present invention will be described. In the first to third embodiments, when the calculation result of equations (2) and (3) is the same, the state judging unit 82 determines that the measurement target 11 is in the small displacement state, and the equations (4) and (4) When the calculation result of Formula 5 is the same, it was determined that the measurement object 11 is in a displacement state. However, when the calculation results of the equations (2) and (3) are the same and the calculation results of the equations (4) and (5) are the same under the influence of noise, the state of the measurement target 11 cannot be determined. Even when the calculation results of the equations (2) and (3) do not coincide, and the calculation results of the equations (4) and (5) do not coincide, the state of the measurement target 11 cannot be determined. In this embodiment, even when the state judging unit 82 cannot determine the state of the measurement target 11, the distance from the measurement target 11 and the speed of the measurement target 11 are realized.

Also in this embodiment, since the configuration of the distance / speedometer is the same as that of the first embodiment, the description will be made using the symbols of FIG. FIG. 33 is a block diagram showing an example of the configuration of the computing device 8 of the present embodiment, and FIG. 34 is a flowchart showing the operation of the computing device 8. The arithmetic unit 8 of the present embodiment uses the measurement target (based on the calculation results of the storage unit 80, the distance / speed calculation unit 81, the distance / speed calculation unit 81, and the hysteresis displacement calculator described later). A state judging 82a for determining the state of 11, a speed estimating 83a for determining the speed of the measurement target 11 based on the determination result of the state judging 82a, and a state judging 82a. The difference between the distance confirmation 84a for determining the distance from the measurement target 11 and the distance candidate value calculated by the distance / speed calculation unit 81 and the distance candidate value calculated immediately before The history displacement calculation unit 85 calculates a history displacement. The speed confirmation 83a and the distance confirmation 84a constitute a distance / speed determination unit 86a.

First, the operation of the storage unit 80 of the computing device 8 is the same as step S201 of FIG. 8 (step S501 of FIG. 34), and the operation of the distance / speed calculating unit 81 is the same as step S202 of FIG. 8. (Step S502 of Fig. 34).

The hysteresis displacement calculator 85 of the computing device 8 determines the second candidate value Lα2 (t-1, t) of the distance from t to time t-1 and the distance from t-1 to time t-2. The hysteresis displacement Vcalα1 (t-2, t), which is the difference between the first candidate value Lα1 (t-2, t-1), and the first candidate value Lα1 (t, t + 1) of the distance from time t to t + 1; The first candidate of the distance at time t-1 from the history displacement Vcalα2 (t-1, t + 1), which is the difference between the second candidate values Lα2 (t-1, t) of the distance from t to time t-1. History displacement Vcalα3 (t-2, t), which is the difference between the value Lα (t-1, t) and the second candidate value Lα2 (t-2, t-1) of the distance from time t-2 to t-1 Hysteresis displacement Vcalα4 (the difference between the second candidate value Lα2 (t, t + 1) of the distance from t to t + 1 and the first candidate value Lα1 (t-1, t) of the distance from t to time t-1 t-1, t + 1), the fourth candidate value Lβ4 (t-1, t) of the distance at t from time t-1 and the third candidate value Lβ3 (the distance at t-1 from time t-2 Hysteresis displacement Vcalβ1 (t-2, t), which is the difference between t-2 and t-1), t + 1 from time t Hysteresisal displacement Vcalβ2 (t-1, t) which is the difference between the third candidate value Lβ3 (t, t + 1) of the distance from the second distance and the fourth candidate value Lβ4 (t-1, t) of the distance from t to the time t-1. +1), the third candidate value Lβ3 (t-1, t) of the distance from t to the time t-1 and the fourth candidate value Lβ4 (t-2, t of the distance from t-1 to the time t-2 Hysteresisal displacement Vcalβ3 (t-2, t), which is the difference of -1), the fourth candidate value Lβ4 (t, t + 1) of the distance at time t + 1 from time t and the distance at t from time t-1 The hysteresis displacement Vcal beta 4 (t-1, t + 1), which is the difference between the three candidate values L beta 3 (t-1, t), is calculated as shown in the following equation and stored in the storage unit 80 (step S503 in Fig. 34).

Vcalα1 (t-2, t) = Lα2 (t-1, t)-Lα1 (t-2, t-1)

Vcalα2 (t-1, t + 1) = Lα1 (t, t + 1) -Lα2 (t-1, t)

Vcalα3 (t-2, t) = Lα1 (t-1, t)-Lα2 (t-2, t-1)

Vcalα4 (t-1, t + 1) = Lα2 (t, t + 1)-Lα1 (t-1, t)

Vcalβ1 (t-2, t) = Lβ4 (t-1, t)-Lβ3 (t-2, t-1)

Vcalβ2 (t-1, t + 1) = Lβ3 (t, t + 1)-Lβ4 (t-1, t)

Vcalβ3 (t-2, t) = Lβ3 (t-1, t)-Lβ4 (t-2, t-1)

Vcalβ4 (t-1, t + 1) = Lβ4 (t, t + 1)-Lβ3 (t-1, t)

Hysteresis displacement Vcalα1 (t-2, t), Vcalα2 (t-1, t + 1), Vcalα3 (t-2, t), Vcalα4 (t-1, t + 1) are the microdisplacements of the measurement target 11 It is calculated on the assumption that it is in the state, and the hysteresis displacements Vcalβ1 (t-2, t), Vcalβ2 (t-1, t + 1), Vcalβ3 (t-2, t), and Vcalβ4 (t-1, t + 1 Is a value calculated on the assumption that the measurement target 11 is in a displacement state.

The hysteresis displacement calculation unit 85 executes the calculation of the equations (34) to (41) for each time the counting device 7 calculates the number of MHPs. On the other hand, in the equations (34) to (41), the direction in which the measurement target 11 approaches the distance / speedometer is determined as the positive speed and the direction away from the negative speed.

Subsequently, the state determination unit 82a of the computing device 8 measures using the calculation result of the equations (2) to (5) and the calculation result of the equations (34) to (41) stored in the storage unit 80. The state of the object 11 is determined (step S504 of FIG. 34). 35 is a flowchart showing the operation of this state determining unit 82a.

First, the state determination unit 82a determines the state of the measurement target 11 using the calculation result of Equations 2 to 5, similarly to the state determination unit 82 of the first embodiment (step of FIG. 35). S601).

Here, when the calculation results of the equations (2) and (3) are the same, the state judging unit 82a determines that the measurement target 11 is in the small displacement state, and the calculation results of the equations (4) and (5) are the same. In this case, it is determined that the measurement target 11 is in the displaced state, it is determined that the state determination is finished (the determination 'Yes' in step S602), and the process of step S504 ends. On the other hand, the state judging unit 82a has the same calculation result as in equations (2) and (3), and the calculation results in equations (4) and (5) are the same, or the calculation results in equations (2) and (3) are the same. If the calculation results of the equations (4) and (5) do not coincide with each other, the state determination is impossible and the flow advances to step S603.

In step S603, the state determination unit 82a determines the state of the measurement target 11 by using the calculation results of the equations (2) to (5) and the calculation results of the equations (34) to (41).

As described in Japanese Patent Laid-Open No. 2006-313080, when the measurement target 11 is moving in a small displacement state (equivalent velocity movement), the hysteresis displacement calculated on the assumption that the measurement target 11 is a small displacement state. The sign of Vcalα is constant, and the average value of the absolute value of the velocity candidate value Vα and the hysteresis displacement Vcalα calculated on the assumption that the measurement target 11 is in a microdisplacement state becomes equal. In addition, when the measurement object 11 is in constant velocity motion in the microdisplacement state, the sign of the hysteresis displacement Vcalβ calculated on the assumption that the measurement object 11 is the displacement state is inverted at each time at which the number of MHPs is calculated. .

Therefore, the state determination unit 82a calculates the hysteresis displacement Vcalα1 (t-2, t) of Equation 34 and the hysteresis displacement Vcalα 2 (t) of Equation 35 calculated on the assumption that the measurement target 11 is in the microdisplacement state. -1, t + 1) and the average value of the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated on the assumption that the signs match and that the measurement target 11 is in the microdisplacement state. When the absolute value of the hysteresis displacement Vcalα1 (t-2, t) and the average value of the absolute values of the hysteresis displacement Vcalα2 (t-1, t + 1) are the same, the measurement target 11 is subjected to constant velocity motion in the microdisplacement state. Determine that you are doing

Alternatively, the state judging 82a calculates the hysteresis displacement Vcalα3 (t-2, t) of Equation 36 and the hysteresis displacement Vcalα4 (t-) of Equation 37 calculated on the assumption that the measurement target 11 is in the microdisplacement state. 1 and t + 1) coincide with each other, and the average of the velocity candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated on the assumption that the measurement target 11 is in the microdisplacement state. When the absolute value of the hysteresis displacement Vcalα3 (t-2, t) and the average value of the hysteresis displacement Vcalα4 (t-1, t + 1) are the same, the measurement target 11 performs the constant velocity motion in the micro displacement state. Is determined to be.

As described in Japanese Patent Laid-Open No. 2006-313080, when the measurement target 11 is moving in the displacement state (equivalent velocity movement), the hysteresis displacement (Vcalβ) calculated on the assumption that the measurement target 11 is the displacement state. Is constant, and the average value of the absolute value of the speed candidate value Vβ and the hysteresis displacement Vcalβ calculated on the assumption that the measurement target 11 is in the displacement state is the same. In addition, when the measurement object 11 is performing the constant velocity motion in the displacement state, the sign of the hysteresis displacement Vcalα calculated on the assumption that the measurement object 11 is the microdisplacement state is inverted at each time the number of MHPs is calculated. .

Therefore, the state judgment unit 82a calculates the hysteresis displacement Vcalβ1 (t-2, t) of Equation 38 and the hysteresis displacement Vcalβ2 (t-1) of Equation 39 calculated on the assumption that the measurement target 11 is in the displacement state. , t + 1) coincide, and the average of the speed candidate values Vβ3 (t, t + 1) and Vβ4 (t, t + 1) calculated on the assumption that the measurement object is in the displacement state, and the hysteresis displacement When the absolute value of Vcalβ1 (t-2, t) and the average value of the absolute value of hysteresisal displacement Vcalβ2 (t-1, t + 1) are the same, it is determined that the measurement target 11 is carrying out constant velocity motion in the displacement state. .

Alternatively, the state judging 82a calculates the hysteresis displacement Vcalβ3 (t-2, t) of Equation 40 and the hysteresis displacement Vcalβ4 (t-1) of Equation 41 calculated on the assumption that the measurement object 11 is in the displacement state. , t + 1) coincide with each other, and the average of the candidate velocity values Vβ3 (t, t + 1) and Vβ4 (t, t + 1) calculated on the assumption that the measurement object is in the displacement state, and the hysteresis displacement Vcalβ3 When the absolute value of (t-2, t) and the average value of the absolute value of hysteresisal displacement Vcal beta 4 (t-1, t + 1) are the same, it is determined that the measurement target 11 is carrying out constant velocity motion in the displacement state.

As described in Japanese Patent Laid-Open No. 2006-313080, in the case where the measurement target 11 is performing a motion other than the constant velocity movement in the microdisplacement state, the speed calculated on the assumption that the measurement target 11 is the microdisplacement state. The average value of the absolute values of the hysteresis displacement Vcalα calculated on the assumption that the candidate value Vα and the measurement target 11 are in a microdisplacement state does not coincide. Similarly, the average value of the absolute value of the speed candidate value Vβ calculated on the assumption that the measurement object 11 is in the displacement state and the hysteresis displacement Vcalβ calculated on the assumption that the measurement object 11 is the displacement state does not coincide.

In addition, when the measurement target 11 is performing a motion other than the constant velocity movement in the microdisplacement state, the sign of the hysteresis displacement Vcalα calculated on the assumption that the measurement target 11 is the microdisplacement state is calculated as the number of MHPs. Even if there is a change in the sign in the hysteresis displacement Vcal beta calculated by assuming that the measurement object 11 is in a displacement state, the change does not occur every time the number of MHPs is calculated.

Therefore, the state judging 82a calculates the hysteresis displacement Vcalα1 (t-2, t) of Equation 34 and the hysteresis displacement Vcalα2 (t-) of Equation 35 calculated on the assumption that the measurement target 11 is in the microdisplacement state. 1, t + 1) do not coincide, and the velocity candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated on the assumption that the measurement target 11 is in a microdisplacement state. If the mean value and the absolute value of the hysteresisal displacement Vcalα1 (t-2, t) and the average value of the absolute values of the hysteresisal displacement Vcalα2 (t-1, t + 1) do not coincide, the measurement target 11 is in a small displacement state. It is determined that a movement other than the constant velocity movement is performed.

Alternatively, the state judging 82a calculates the hysteresis displacement Vcalα3 (t-2, t) of Equation 36 and the hysteresis displacement Vcalα4 (t-) of Equation 37 calculated on the assumption that the measurement target 11 is in the microdisplacement state. 1, t + 1) do not coincide, and the velocity candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated on the assumption that the measurement target 11 is in a microdisplacement state. If the mean value and the absolute value of the hysteresisal displacement Vcalα3 (t-2, t) and the average value of the absolute values of the hysteresisal displacement Vcalα4 (t-1, t + 1) do not coincide, the measurement target 11 is in a small displacement state. It is determined that a movement other than the constant velocity movement is performed.

On the other hand, when focusing on the velocity candidate value Vβ, the absolute value of Vβ3 (t, t + 1) and the absolute value of Vβ4 (t, t + 1) become integers, and the absolute value is determined by the measurement target 11. The wavelength change rate (λb-λa) of the semiconductor lasers (1-1, 1-2) is calculated from the average values of the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t + 1) calculated on the assumption that they are in a small displacement state. equal to the product of) / λb. Thus, the state judging 82a calculates the absolute value of the velocity candidate value Vβ 3 (t, t + 1) and the absolute value of Vβ4 (t, t + 1) calculated on the assumption that the measurement object 11 is in the displacement state. The value is equal to the average value of the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t + 1) multiplied by the wavelength change rate (λb−λa) / λb, and the measurement target 11 has a small displacement. The average value of the velocity candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1) calculated on the assumption that they are in the state, the absolute value of the historical displacement Vcalα1 (t-2, t), and the history displacement Vcalα2 (t In the case where the average value of the absolute values of −1 and t + 1) does not coincide, it may be determined that the measurement target 11 is performing a motion other than the constant velocity motion in the microdisplacement state.

Further, the state judging 82a calculates the absolute value of the speed candidate value Vβ3 (t, t + 1) and the absolute value of Vβ4 (t, t + 1) calculated on the assumption that the measurement target 11 is in the displacement state. The mean value of the distance candidate values Lα1 (t, t + 1) and Lα2 (t, t + 1) is equal to the value obtained by multiplying the wavelength change rate (λb−λa) / λb, and the measurement target 11 has a small displacement. The average value of the speed candidate values Vα1 (t, t + 1) and Vα2 (t, t + 1), the absolute value of the hysteresis displacement Vcalα3 (t-2, t) and the hysteresis displacement Vcalα4 (t In the case where the average value of the absolute values of −1 and t + 1) does not coincide, it may be determined that the measurement target 11 is performing a motion other than the constant velocity motion in the microdisplacement state.

As described in Japanese Patent Laid-Open No. 2006-313080, in the case where the measurement target 11 is performing a motion other than the constant velocity movement in the displacement state, the velocity candidate calculated by assuming that the measurement target 11 is a microdisplacement state. Velocity candidate value calculated by assuming that the mean value of the absolute value of the hysteresisal displacement Vcalα calculated on the assumption that the value Vα and the measurement target 11 are in the small displacement state does not coincide, and that the measurement target 11 is the displacement state. The average value of the absolute values of the hysteresisal displacements Vcalβ calculated by assuming that Vβ and the measurement target 11 are in a displaced state also does not coincide. In addition, when the measurement target 11 is in the displacement state other than the constant velocity movement, the sign of the hysteresis displacement Vcalβ calculated on the assumption that the measurement target 11 is the displacement state is the time at which the number of MHPs is calculated. In the hysteresis displacement Vcalα calculated on the assumption that the measurement target 11 is in a small displacement state, even if there is a change in the sign, this change does not occur every time the number of MHPs is calculated.

Therefore, the state judgment unit 82a calculates the hysteresis displacement Vcalβ1 (t-2, t) of Equation 38 and the hysteresis displacement Vcalβ2 (t-1) of Equation 39 calculated on the assumption that the measurement target 11 is in the displacement state. , t + 1) do not coincide with each other, and the average value of the velocity candidate values Vβ3 (t, t + 1) and Vβ4 (t, t + 1) calculated on the assumption that the measurement target 11 is in the displacement state. If the absolute value of the hysteresis displacement Vcalβ1 (t-2, t) and the average value of the hysteresis displacement Vcalβ2 (t-1, t + 1) do not coincide, the measurement target 11 is subjected to constant velocity Determine if you are exercising.

Alternatively, the state judging 82a calculates the hysteresis displacement Vcalβ3 (t-2, t) of Equation 40 and the hysteresis displacement Vcalβ4 (t-1) of Equation 41 calculated on the assumption that the measurement object 11 is in the displacement state. , t + 1) do not coincide with each other, and the average value of the velocity candidate values Vβ3 (t, t + 1) and Vβ4 (t, t + 1) calculated on the assumption that the measurement target 11 is in the displacement state. If the absolute value of the hysteresis displacement Vcalβ3 (t-2, t) and the average value of the hysteresis displacement Vcalβ4 (t-1, t + 1) do not coincide, Determine if you are exercising.

On the other hand, when focusing on the speed candidate value Vα, the absolute value of Vα1 (t, t + 1) and the absolute value of Vα2 (t, t + 1) become integers, and this absolute value is determined by the measurement target 11. The wavelength change rate (λb-λa) of the semiconductor lasers (1-1, 1-2) is calculated from the average values of the distance candidate values Lβ3 (t, t + 1) and Lβ4 (t, t + 1) calculated on the assumption that they are in a displacement state. equal to the product of) / λb. Thus, the state judging 82a calculates the absolute value of the velocity candidate value Vα1 (t, t + 1) and the absolute value of Vα2 (t, t + 1) calculated on the assumption that the measurement target 11 is in the microdisplacement state. The value is equal to the average value of the distance candidate values Lβ3 (t, t + 1) and Lβ4 (t, t + 1) multiplied by the wavelength change ratio (λb-λa) / λb, and the measurement target 11 is in a displacement state. The average value of the speed candidate values Vβ3 (t, t + 1) and Vβ4 (t, t + 1), the absolute value of the hysteresis displacement Vcalβ1 (t-2, t), and the hysteresis displacement Vcalβ2 (t- When the average value of the absolute values of 1, t + 1) does not match, you may determine that the measurement object 11 is carrying out movement other than the constant velocity motion in a displacement state.

Alternatively, the state judging 82a calculates the absolute value of the velocity candidate value Vα1 (t, t + 1) and the absolute value of Vα2 (t, t + 1) calculated on the assumption that the measurement target 11 is in the microdisplacement state. The value is equal to the average value of the distance candidate values Lβ3 (t, t + 1) and Lβ4 (t, t + 1) multiplied by the wavelength change ratio (λb-λa) / λb, and the measurement target 11 is in a displacement state. The average value of the velocity candidate values Vβ3 (t, t + 1) and Vβ4 (t, t + 1), the absolute value of the hysteresis displacement Vcalβ3 (t-2, t), and the hysteresis displacement Vcalβ4 (t- When the average value of the absolute values of 1, t + 1) does not match, you may determine that the measurement object 11 is carrying out movement other than the constant velocity motion in a displacement state.

Thus, the process of step S603 ends. Table 1 shows the determination operation of step S603 of the state judging unit 82a.

Hysteresis Velocity candidate Vcalα Vcalβ Vα Vβ



move

smile
Displacement Schedule

Velocity candidates and
The mean value of the absolute value of the hysteresis displacement is identical
Every time code is calculated
reversal

-

-

Displacement
Every time code is calculated
reversal Schedule

Velocity candidates and
The mean value of the absolute value of the hysteresis displacement is identical

-

-





vibration


smile
Displacement Every time code is calculated
reversal

Velocity candidates and
The mean value of the absolute value of the hysteresis displacement is inconsistent


-


- The absolute value of the velocity candidate value agrees with the wavelength candidate rate multiplied by the distance candidate value calculated assuming that the measurement object is in a microdisplacement state.

Displacement


-
Every time code is calculated
reversal

Velocity candidates and
The mean value of the absolute value of the hysteresis displacement is inconsistent
The absolute value of the velocity candidate value coincides with the wavelength candidate rate multiplied by the distance candidate value calculated assuming that the measurement object is in the displacement state.


-

Subsequently, the speed determination 83a of the computing device 8 determines the absolute value of the speed of the measurement target 11 based on the determination result of the state determination 82a (step S505 in Fig. 34). In other words, when it is determined that the measurement target 11 is performing a motion other than the constant speed motion or the constant speed motion in the microdisplacement state, the speed confirmation 83a determines the speed candidate value Vα1 (stored in the storage unit 80 ( The average value of t, t + 1) and V alpha 2 (t, t + 1) is determined as the absolute value of the velocity of the measurement target 11 at t + 1 from time t-1 (step S505).

In addition, when it is determined that the measurement target 11 is performing a motion other than the constant speed motion or the constant speed motion in the displacement state, the speed confirmation 83a determines the speed candidate value Vβ3 (t) stored in the storage unit 80 (t). , the average value of t + 1) and Vβ4 (t, t + 1) is determined as the absolute value of the velocity of the measurement target 11 at t + 1 from time t-1 (step S505).

On the other hand, when it is determined that the measurement target 11 is performing a motion other than the constant speed motion or the constant speed motion in the microdisplacement state, the speed confirmation 83a determines the speed candidate value Vα5 (stored in the memory 80). t) may be determined to be the absolute value of the velocity of the measurement target 11 at t + 1 from time t-1 (step S505). In addition, when it is determined that the measurement target 11 is performing a motion other than the constant speed motion or the constant speed motion in the displacement state, the speed confirmation 83a determines the speed candidate value Vβ6 (t stored in the storage unit 80 (t). ) May be determined as the absolute value of the speed of the measurement target 11 at time t-1 (step S505).

Next, the speed confirmation 83a calculates the equations (14) and (15) as in step S205 of FIG. 8 to determine the speed direction of the measurement target 11 (step S506 in FIG. 34). On the other hand, when the speed determiner 83a determines the absolute value of the speed using the calculation result of Equation 6 or 7, instead of using the calculation result of Equation 2 to Equation 5 in step S505, the number of MHPs is determined. By comparing the sizes of X (t) and Y (t), if X (t) is larger than Y (t), it is determined that the measurement target 11 is closer, and if Y (t) is larger than X (t), the measurement is made. It is determined that the object 11 is moving away (step S506).

Subsequently, the distance determination 84a determines the distance to the measurement target 11 based on the determination result of the state judging 82a (step S507 in Fig. 34). That is, when it is determined that the measurement target 11 is performing a motion other than the constant velocity motion or the constant velocity motion in the microdisplacement state, the distance determiner 84a stores the distance candidate value Lα1 (stored in the storage unit 80 ( The average value of t, t + 1) and Lα2 (t, t + 1) is determined as the average distance from the time t-1 to the measurement object 11 at t + 1 (step S507).

In addition, when it is determined that the measurement target 11 is performing a motion other than the constant velocity motion or the constant velocity motion in the displacement state, the distance confirming 84a stores the distance candidate value Lβ3 (t) stored in the storage unit 80 (t). , t + 1) and Lβ4 (t, t + 1) are determined as the average distance from the time t-1 to the measurement target 11 at t + 1 (step S507).

On the other hand, when it is determined that the measurement target 11 is performing a motion other than the constant velocity motion or the constant velocity motion in the microdisplacement state, the distance determiner 84a stores the distance candidate value Lα5 (stored in the storage unit 80 ( t) may be determined as an average distance from the time t-1 to the measurement target 11 at t (step S507). Further, when it is determined that the measurement target 11 is performing a motion other than the constant velocity motion or the constant velocity motion in the displacement state, the distance confirmation 84a stores the distance candidate value Lβ6 (stored in the storage unit 80 ( t) may be determined as an average distance from the time t-1 to the measurement target 11 at t (step S507).

The computing device 8 carries out the processing of steps S501 to S507 as described above, for example, until the measurement end instruction is received from the user (YES in step S508 of FIG. 34). It is performed every time the number is calculated. The configuration other than the computing device 8 is the same as in the first embodiment.

In this embodiment, even when the state of the measurement object 11 cannot be determined in the first embodiment due to the influence of noise or the like, the state of the measurement object 11 is determined and the distance from the measurement object 11 and The speed of the measurement object 11 can be calculated.

[Fifth Embodiment]

Next, a fifth embodiment of the present invention will be described. When the measurement target 11 is performing a motion other than the constant velocity movement, when the acceleration code of the measurement target 11 is changed, the sign of the formula other than the corresponding region of the movement state is reversed, and a judgment error occurs. Thus, in the fourth embodiment, the state determination unit 82a of the computing device 8 is the hysteresis displacement Vcalα2 (t-1, t + 1) of Equation 35 and the hysteresis displacement Vcalα4 (t-1, Equation 37). If the signs of t + 1) coincide, it is determined that the measurement target 11 is in constant velocity motion, and the hysteresis displacement Vcalβ2 (t-1, t + 1) in Equation 39 and the hysteresis displacement Vcalβ4 in Equation 41 are determined. When the signs of (t-1, t + 1) coincide, it may be determined that the measurement target 11 is performing a motion other than the constant velocity motion.

[Sixth Embodiment]

In the first to fifth embodiments, the case where the present invention is applied to the self-coupled interferometer has been described, but the present invention can also be applied to interferometers other than the self-coupled interferometer. Fig. 36 is a block diagram showing the construction of the distance / speedometer according to the sixth embodiment of the present invention. The same reference numerals are used for the same construction as in Fig. 1. In FIG. 36, 12-1 and 12-2 are beam splitters that separate incident light and reflected light.

The laser beams of the semiconductor lasers 1-1 and 1-2 are emitted in parallel to each other and enter the measurement target 11 as in the first embodiment. The laser light passing through the beam splitters 12-1 and 12-2 and the lenses 3-1 and 3-2 is incident on the measurement target 11. In the present embodiment, the light of the semiconductor lasers 1-1 and 1-2 reflected from the measurement target 11 is directed to the measurement target 11 by the beam splitters 12-1 and 12-2, respectively. Is separated from the incident light at and sent to the photodiodes 2-1 and 2-2.

Since the structures after the photodiodes 2-1 and 2-2 are the same as those in the first to fifth embodiments, description thereof is omitted. In this way, the same effects as those in the first to fifth embodiments can be obtained also in interferometers other than the magnetic coupling type.

The counting device 7 and the computing device 8 in the first to sixth embodiments can be realized by, for example, a computer having a CPU, a storage device and an interface, and a program for controlling their hardware resources. A program for operating such a computer is provided in a state recorded in a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, a memory card, or the like. The CPU writes the read program to the storage device, and executes the processing described in the first to sixth embodiments in accordance with this program.

On the other hand, in the first to sixth embodiments, when the measurement target 11 makes a vibration having a very small displacement (for example, a maximum speed of 2 nm), the change in the actual distance (amplitude) is several nm, but the distance calculation is performed. The error is large because the resolution of is lower than the displacement resolution. Therefore, when the measurement object is in a motion state with a small displacement, the accuracy in which the value obtained by integrating the displacement (speed) instead of the calculation result is called a change in distance is improved.

In the first to sixth embodiments, the minimum oscillation wavelength? A of the semiconductor laser 1-1 and the semiconductor laser 1-2 is the same, and the semiconductor laser 1-1 and the semiconductor laser 1- 1 are the same. Although the case where the maximum oscillation wavelength lambda b of 2) is the same has been described, the present invention is not limited to this, and as shown in FIG. 37, the minimum oscillation is performed between the semiconductor laser 1-1 and the semiconductor laser 1-2. The wavelength lambda a and the maximum oscillation wavelength lambda b may be different from each other. In FIG. 37, lambda a1 and lambda b1 are the minimum oscillation wavelength and maximum oscillation wavelength of the semiconductor laser 1-1, and lambda a2 and lambda b2 are the minimum oscillation wavelength and the maximum oscillation wavelength of the semiconductor laser 1-2. In this case, λa1 × λb1 / {4 × (λb1-λa1)} and λa2 × λb2 / {4 × (λb2-λa2)} may always be the same fixed value. In this case, λa1 and λb1 may be used as λa and λb in Equations 2 to 13, and λa2 and λb2 may be used.

Incidentally, in the first to sixth embodiments, the semiconductor lasers 1-1 and 1-2 were oscillated in a triangular wave shape, but the present invention is not limited thereto, and the semiconductor lasers 1-1 and 1- 1 are shown in FIG. 2) may be oscillated in a sawtooth wave shape. That is, in the present invention, the semiconductor laser 1-1 is operated so that at least the first oscillation period P1 is repeatedly present, and the semiconductor laser 1- 1 is operated so that the increase and decrease of the semiconductor laser 1-1 and the oscillation wavelength are reversed. 2) can be operated. Similarly to the case of FIG. 37, λa1 ≠ λa2, λb1 ≠ λb2, or λa1 = λa2, λb1 = λb2, as in the case of FIG.

The operation in the first oscillation period P1 is the same as that of the triangular wave oscillation. However, when the semiconductor lasers 1-1 and 1-2 are oscillated in a sawtooth wave shape, the outputs of the changeover switches 70 and 70a of the counter 7 need to be fixed. That is, the changeover switches 70 and 70a always connect the output of the filter circuit 6-1 to the inputs of the period measuring unit 71-1 and the determination unit 73-1, and the filter circuit 6-2. Is always connected to the input of the period measuring unit 71-2 and the determining unit 73-2.

On the other hand, when the semiconductor lasers 1-1 and 1-2 are oscillated in a triangular wave shape, amplitude adjustment by the amplitude adjusting device 10 is possible regardless of the state of the measurement target 11, but the semiconductor lasers 1-1 , 1-2), oscillation can be performed only when the measurement target 11 is stationary.

1 is a block diagram showing the configuration of a distance / speedometer as a first embodiment of the present invention.

2 is a diagram showing an example of time variation of the oscillation wavelength of a semiconductor laser in the first embodiment of the present invention.

3 (a) and 3 (b) are diagrams schematically showing output voltage waveforms of the two current-voltage conversion amplifiers in the first embodiment of the present invention, and FIGS. 3 (c) and (d) Of the present invention It is a figure which shows typically the output voltage waveform of each of the two filter circuits in a 1st Example.

Fig. 4 is a block diagram showing an example of the configuration of the counting device in the first embodiment of the present invention.

5 is a flowchart illustrating the operation of the counter of FIG. 4.

6 is a diagram illustrating a counting period of the counting device of FIG. 4.

Fig. 7 is a block diagram showing an example of the configuration of the computing device in the first embodiment of the present invention.

8 is a flowchart illustrating an operation of the computing device of FIG. 7.

FIG. 9 is a diagram for explaining the change in the number of mode hop pulses that accompany the change of the wavelength change of the semiconductor laser.

FIG. 10 is a view for explaining a method of adjusting the amplitude of the triangular wave driving current supplied from the laser driver to the semiconductor laser in the first embodiment of the present invention.

FIG. 11 is a diagram for explaining a method of having continuity in the calculation result of the speed or distance before and after the timing at which the wavelength change of the semiconductor laser is switched.

Fig. 12 is a block diagram showing an example of the configuration of the counting device in the second embodiment of the present invention.

13 is a flowchart showing the operation of the counter of FIG.

FIG. 14 is a block diagram illustrating an example of a configuration of a count result correcting unit in the counting device of FIG. 12.

FIG. 15 is a view for explaining the operation of the counter of FIG.

16 is a diagram illustrating an example of frequency distribution of a mode hop pulse period.

17 is a diagram for explaining the principle of correction of the counter counting result in the second embodiment of the present invention.

18 is a diagram showing the frequency distribution of a mode hop pulse period.

19 is a diagram showing the frequency distribution of a mode hop pulse period including noise.

20 is a diagram illustrating a median value of a mode hop pulse period including noise.

21 is a diagram illustrating a probability distribution of a mode hop pulse period in which a period is divided into two.

22 is a diagram showing the frequency distribution of a mode hop pulse period in which a period is divided into two.

FIG. 23 is a diagram showing the frequency distribution of a mode hop pulse period in which a period is divided into two.

24 is a diagram showing the frequency distribution of a mode hop pulse period in which a period is divided into two.

25 is a diagram illustrating an error after counter value correction.

FIG. 26 is a diagram showing the frequency distribution of a mode hop pulse period that has been doubled.

Fig. 27 is a diagram showing the frequency distribution of a mode hop pulse period divided into two of the mode hop pulses dropped at the time of counting.

Fig. 28 is a diagram showing the frequency distribution of a mode hop pulse period divided into two of the mode hop pulses dropped at the time of counting.

Fig. 29 is a diagram showing the frequency distribution of the mode hop pulse periods when missing and excess counts occur at the time of counting.

Fig. 30 is a block diagram showing an example of the configuration of the counting device in the third embodiment of the present invention.

FIG. 31 is a flowchart showing the operation of the counter of FIG.

32 is a block diagram illustrating an example of a configuration of a count result correcting unit in the counting device of FIG. 30.

Fig. 33 is a block diagram showing an example of the configuration of the arithmetic unit in the fourth embodiment of the present invention.

34 is a flowchart illustrating the operation of the arithmetic apparatus of FIG. 33.

35 is a flowchart showing the operation of the state determination unit in the arithmetic unit of FIG.

Fig. 36 is a block diagram showing the construction of a distance / speedometer as a sixth embodiment of the present invention.

Fig. 37 is a diagram showing another example of the time variation of the oscillation wavelength of the Bandore laser in the first to sixth embodiments of the present invention.

Fig. 38 is a diagram showing another example of the time variation of the oscillation wavelength of the Bandore laser in the first to sixth embodiments of the present invention.

Fig. 39 is a diagram showing a model of a compound resonator of a semiconductor laser in a conventional laser measuring instrument.

Fig. 40 shows the relationship between the oscillation wavelength of a semiconductor laser and the output wavelength of a built-in photodiode.

Fig. 41 is a block diagram showing the structure of a conventional distance / speedometer.

FIG. 42 is a diagram illustrating an example of time variation of an oscillation wavelength of a semiconductor laser in the distance / speed meter of FIG. 41.

Claims (19)

A first semiconductor laser 1-1 emitting a first laser light to the measurement target 11; A second semiconductor laser (1-2) emitting a second laser light in parallel with the first laser light to the measurement object; A first laser driver 4-1 for driving the first semiconductor laser so that at least an oscillation wavelength continuously monotonically increases an oscillation period; A second laser driver 4-2 for driving the second semiconductor laser so that the increase and decrease of the first semiconductor laser and the oscillation wavelength are reversed; A first light receiver 2-1 for converting at least the light output of the first semiconductor laser into an electrical signal; A second light receiver 2-2 for converting at least the light output of the second semiconductor laser into an electrical signal; A number of interference waveforms generated by the first laser light and the return light from the measurement target of the first laser light, included in the output signal of the first light receiver, and included in the output signal of the second light receiver; Counting means (13) for counting the number of interference waveforms generated by the return light from the measurement object of the second laser light and the second laser light, respectively; Calculating means (8) for calculating at least one of the distance between the measurement object and the speed of the measurement object from the minimum oscillation wavelength and the maximum oscillation wavelength of the first and second semiconductor lasers and the counting result of the counting means; The counting means is an output signal of a light receiver corresponding to a semiconductor laser in which an oscillation wavelength is increased among the first and second semiconductor lasers in a first counting period shorter than an oscillation period of the first and second semiconductor lasers. The number of the interference waveforms included in the circuit is determined, and at the same time as the first counting period, the output of the light receiver corresponding to the semiconductor laser in which the oscillation wavelength of the first and second semiconductor lasers is decreasing. Find the number of interference waveforms in the signal, The calculating means calculates the distance candidate value from the measurement target and the speed candidate value from the measurement target based on the minimum oscillation wavelength and the maximum oscillation wavelength of the first and second semiconductor lasers and the counting result of the counting means. / Speed calculating means (81), State determination means (82, 82a) for determining the state of the measurement object based on the speed candidate value calculated by the distance / speed calculation means; And distance / speed determination means (86, 86a) for determining at least one of a distance from the measurement object and a speed of the measurement object, based on the determination result of the state determination means. delete delete delete The method of claim 1, The distance / speed calculating means is adapted to calculate the distance between the first candidate value of the speed and the distance from the counting result of the first counting period and the counting result of the second counting period after the assumption that the measurement target is in the microdisplacement state. The first candidate value is calculated, and the counting result of the second counting period at the same time as the first counting period in which the first candidate values are calculated, and the first counting time at the same time as the second counting period in which the first candidate value is calculated. Counting result of the first counting period, when the second candidate value of velocity and the second candidate value of the distance are calculated from the counting result of the counting period, and the measurement object is assumed to be in a displacement state where the movement is sharper than the microdisplacement state. And a second counting period at the same time as the first counting period in which the third candidate value of the speed and the third candidate value of the distance are calculated from the counting result of the second counting period one time later and the third candidate values are calculated. Counting results and third candidate A first calculates a fourth candidate value of the fourth candidate value of the speed and distance from the count of the first counting interval of time, such as two-term factor calculated, The state determining means determines that the measurement object is in the microdisplacement state when the first candidate value and the second candidate value of the speed calculated by the distance / speed calculating means are the same, and is calculated by the distance / speed calculating means. The distance / speedometer which determines that a measurement object is in a displacement state, when the 3rd candidate value and the 4th candidate value of speed are the same. The method of claim 5, The distance / speed determination means, when it is determined by the state determination means that the measurement object is in the microdisplacement state, sets either one of the first candidate value and the second candidate value of the speed as the speed of the measurement object, Any one of the first candidate value and the second candidate value is the distance between the measurement object, and when it is determined by the state determination means that the measurement object is in the displaced state, any one of the third candidate value and the fourth candidate value of speed is determined. A distance / speedometer in which one is used as the speed of the measurement object and one of the third and fourth candidate values of the distance is the distance to the measurement object. The method of claim 5, The distance / speed determination means, when it is determined in the state determination means that the measurement object is in the microdisplacement state, sets the average value of the first candidate value and the second candidate value of the speed as the speed of the measurement object, and the first distance of the distance. The average value of the candidate value and the second candidate value is the distance from the measurement object, and when the state determination means determines that the measurement object is in the displacement state, the average value of the third candidate value and the fourth candidate value of speed is measured. A speed / speed meter, wherein the speed is equal to and the average value of the third candidate value and the fourth candidate value of the distance is the distance from the measurement target. The method of claim 5, The distance / speed determination means includes a sum (ΣX) of the counting result of the first counting period for calculating the first candidate value of the speed and the counting result of the first counting period for calculating the second candidate value of the speed, and When the sum (ΣY) of the counting result of the second counting period for which the first candidate value is calculated and the counting result of the second counting period for which the second candidate value of the speed is calculated is compared, and if? The distance / speedometer which determines that the measurement object is moving away when it judges that it is approaching and ΣY is larger than ΣX. The method of claim 5, The calculation means assumes that the hysteresis displacement, which is the difference between the distance candidate value calculated by the distance / speed calculation means and the distance candidate value calculated last time, is assumed to be in a displacement state and assuming that the measurement object is in a small displacement state. Further comprising hysteresis displacement calculating means (85) for calculating each of And the state determining means (82a) determines the state of the measurement object based on the calculation result of the hysteresis displacement calculation means when the state of the measurement object cannot be determined based on the speed candidate value. The method of claim 1, The counting means, Counters 75-1 and 75-2 that count the number of interference waveforms included in the output signals of the first and second receivers with respect to the output signals of the first and second receivers, respectively; Period measuring means 760 for measuring the period of the interference waveform during the counting period in which the interference waveform is counted each time the interference waveform is input to each of the output signals of the first and second receivers, Frequency distribution preparing means 761 which prepares a frequency distribution of the interference waveform period during the counting period for each of the output signals of the first and second light receivers from the measurement result of the period measuring means; A median value calculating means 762 for calculating the median of the interference waveform period for each of the output signals of the first and second receivers from the frequency distribution created by the frequency distribution preparing means; From the frequency distribution created by the frequency distribution creating means, the sum Ns of the degrees of the class less than or equal to the first predetermined multiple of the median value calculated by the median value calculating means, and the total Nw of the degrees of the class greater than or equal to the second predetermined multiple of the median value. Correction value calculating means 763 for correcting the counting result of the counter with respect to each of the output signals of the first and second light receivers based on the sum Ns and Nw; Period sum calculating means (78-1, 78-2) for calculating the sum of the periods of the interference waveform from the measurement results of the period measuring means for each of the output signals of the first and second receivers; A number calculating means for calculating, for each of the output signals of the first and second receivers, the number of interference waveforms per unit time from the sum of the count result corrected by the correction value calculating means and the period calculated by the period sum calculating means; 79-1, 79-2). The method of claim 10, And said correction value calculating means obtains the value N 'after correction by N' = N + Nw-Ns when the counting result of said counter is N. The method of claim 11, The first predetermined number is 0.5 and the second predetermined number is 1.5. The method of claim 1, The counting means, Period measuring means 71a for measuring a period of a predetermined number of interference waveforms included in the output signals of the first and second receivers whenever an interference waveform is input to each of the output signals of the first and second receivers. -1, 71a-2), Frequency distribution preparing means 761a for generating the frequency distribution of the interference waveform period from each of the output signals of the first and second receivers from the measurement result of the period measuring means; A median value calculating means 762a for calculating the median of the interference waveform period for each of the output signals of the first and second receivers from the frequency distribution created by the frequency distribution preparing means; From the frequency distribution created by the frequency distribution creating means, the sum Ns of the degrees of the class less than or equal to the first predetermined multiple of the median value calculated by the median value calculating means, and the total number Nw of the degrees greater than or equal to the second predetermined multiple of the median value. Correction value calculating means 763a for correcting the number of the interference waveforms used for the measurement of the period based on the sum Ns and Nw for each of the output signals of the first and second receivers, Period sum calculating means (78-1, 78-2) for calculating the sum of the periods of the interference waveform from the measurement results of the period measuring means for each of the output signals of the first and second receivers; A number calculation for calculating, for each of the output signals of the first and second receivers, the number of interference waveforms per unit time from the sum of the number of interference waveforms corrected by the correction value calculating means and the period calculated by the period sum calculating means. Distance / speedometer with means (79-1, 79-2). The method of claim 13, And said correction value calculating means obtains the number N 'after correction by N' = N + Nw-Ns when the number of interference waveforms used for measuring the period is N. The method of claim 14, The first predetermined number is 0.5 and the second predetermined number is 1.5. The method of claim 13, The period measuring means outputs a light receiver corresponding to a semiconductor laser in which an oscillation wavelength is increased among the first and second semiconductor lasers in a first counting period shorter than an oscillation period of the first and second semiconductor lasers. The period of the interference waveform included in the signal is determined, and in the second counting period at the same time as the first counting period, the light receiver corresponding to the semiconductor laser whose oscillation wavelength is decreasing among the first and second semiconductor lasers is reduced. Distance / speed meter for finding the period of the interference waveform included in the output signal. Driving the first semiconductor laser emitting the first laser light to the measurement object repeatedly so that at least an oscillation wavelength continuously monotonically increases the oscillation period; Driving a second semiconductor laser that emits a second laser light in parallel with the first laser light to a measurement object such that the increase and decrease of the oscillation wavelength is reversed with the first semiconductor laser; The number of interference waveforms generated by the first laser light and the return light from the measurement target of the first laser light, included in the output signal of the first light receiver, and the second laser, included in the output signal of the second light receiver. A counting step of counting the number of interference waveforms generated by the return light from the measurement target of the light and the second laser light, Calculation for calculating at least one of the distance to the measurement object and the speed of the measurement object from the counting results of the interference waveforms for the minimum and maximum oscillation wavelengths of the first and second semiconductor lasers and the first and second laser beams, respectively With steps, In the counting step, an output signal of a light receiver corresponding to a semiconductor laser in which an oscillation wavelength of the first and second semiconductor lasers is increased in a first counting period shorter than an oscillation period of the first and second semiconductor lasers. The number of the interference waveforms included in the circuit is determined, and at the same time as the first counting period, the output of the light receiver corresponding to the semiconductor laser in which the oscillation wavelength of the first and second semiconductor lasers is decreasing. Obtaining a number of interference waveforms included in the signal, In the calculating step, the distance candidate value and the speed candidate value of the measurement target are calculated based on the minimum and maximum oscillation wavelengths of the first and second semiconductor lasers and the counting result of the counting step. Speed calculation step, A state determination step of determining a state of a measurement object based on the speed candidate value calculated in the distance / speed calculation step; And a distance / speed determination step of determining at least one of a distance to the measurement target and a speed of the measurement target based on the determination result of the state determination step. The method of claim 17, The counting step, A counter for counting the number of interference waveforms included in the output signals of the first and second receivers with respect to the output signals of the first and second receivers, respectively; A period measuring step of measuring a period of the interference waveform during the counting period in which the number of the interference waveforms is counted each time an interference waveform is input to each of the output signals of the first and second receivers; A frequency distribution preparing step of preparing a frequency distribution of the interference waveform period during the counting period for each of the output signals of the first and second receivers from the measurement result of the period measuring step; A median value calculating step of calculating a median value of the interference waveform period for each of the output signals of the first and second receivers from the frequency distribution created in the frequency distribution preparing step; From the frequency distribution created in the frequency distribution preparing step, the sum Ns of the degrees of the class less than or equal to the first predetermined multiple of the median value calculated in the median calculating step Ns, and the total number Nw of the degrees more than the second predetermined multiple of the median value Nw. Calculating a correction value for correcting the counting result of the counter step for each of the output signals of the first and second light receivers based on the sum Ns and Nw; A period sum calculating step of calculating a total sum of the periods of the interference waveforms from the measurement results of the period measuring step for each of the output signals of the first and second receivers; And a number calculating step of calculating, for each of the output signals of the first and second receivers, the number of interference waveforms per unit time from the sum of the count result corrected in the correction value calculating step and the period calculated in the period sum calculating step. Distance / speed measurement method The method of claim 17, The counting step, A period measuring step of measuring a period of a predetermined number of interference waveforms included in output signals of the first and second receivers each time an interference waveform is input to each of the output signals of the first and second receivers; A frequency distribution preparing step of preparing a frequency distribution of the interference waveform period for each of the output signals of the first and second receivers from the measurement result of the period measuring step; A median value calculating step of calculating a median value of the interference waveform period for each of the output signals of the first and second receivers from the frequency distribution created in the frequency distribution preparing step; From the frequency distribution created in the frequency distribution preparing step, the sum Ns of the degrees of the class less than or equal to the first predetermined multiple of the median value calculated in the median calculating step Ns, and the total number Nw of the degrees more than the second predetermined multiple of the median value Nw. Calculating a correction value for correcting the number of interference waveforms used for the measurement of the period based on the sum Ns and Nw for each of the output signals of the first and second receivers, A period sum calculating step of calculating a total sum of the periods of the interference waveforms from the measurement results of the period measuring step for each of the output signals of the first and second receivers; A number calculation for calculating the number of interference waveforms per unit time for each output signal of the first and second receivers from the sum of the number of interference waveforms corrected in the correction value calculating step and the period calculated in the period sum calculating step. A distance / speed measurement method comprising the steps.

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