JP3141120B2 - Phase measuring device and distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase measuring apparatus capable of extracting phase information from the entire waveform of a phase-measured waveform, and more particularly, to a method in which input data is AD-converted and stored in a memory. And a distance measuring device capable of removing defective data.

[0002]

2. Description of the Related Art A conventional pulse type light wave distance meter is shown in FIG.
As shown in the figure, the crystal oscillator 1100 and the first frequency divider 111
0, synthesizer 1120, second frequency divider 1130, third frequency divider 1140, laser diode 1, laser diode driver 1150, APD 71, and amplifier 11
60, waveform shaping circuit 1170, counter 1180, band pass filter 1210, and sample hold (S / H)
1220, low-pass filter 1230, and comparator 1
240 and an arithmetic circuit 1500.

A reference signal of frequency f _S output from crystal oscillator 1100 is supplied to first frequency divider 1110 by (N−1)
Divided by a factor of one. The signal divided by the first divider 1110 is sent to a synthesizer 1120 and multiplied by N times. And the output signal of synthesizer 1120 is
The signal is sent to the second frequency divider 1130 and is divided by 1 / m to be a measurement signal having a frequency f _M.

[0004] The laser diode driver 1150 includes:
The laser diode 1 emits light based on the output signal of the second frequency divider 1130. The light pulse emitted from the laser diode 1 is emitted toward a corner cube which is a point to be measured, and the light pulse reflected by the corner cube is incident on an APD 71 which is a light receiving element.

An optical pulse incident on the APD 71 from the external distance measuring optical path is converted into an electric signal, amplified by an amplifier 1160, converted into a binary digital signal by a waveform shaping circuit 1170, and sample-hold ( S / H) 1
Sent to 220.

[0006] The reference signal of the frequency f _S output from the crystal oscillator 1100 is also sent to the band-pass filter 1210, converted into a sine wave signal, and sample-and-hold (S / S).
H) sent to 1220. Sample hold (S / H)
Numeral 1220 samples and polls the sine wave signal from the bandpass filter 1210 with the digital signal binarized by the waveform shaping circuit 1170.

Here, the relationship between the reference signal of frequency f _S and the measurement signal of frequency f _M is shown.

[0008]

(Equation 1)

[0009]

(Equation 2)

Then, the relationship between f _S and f _M is

[0011]

(Equation 3)

## EQU1 ##

Here, assuming that m dash is an integer, a sample hold (S / H) 1220 converts the sine wave signal from the bandpass filter 1210 into 1 / n of the period of the reference signal f _S for each received pulse. The signals are held in order while the phases are shifted, and a low-frequency step-like signal having a frequency f _L is output. The frequency of f _L is such that the measurement signal of f _M is n
Since one cycle is one time,

[0014]

(Equation 4)

## EQU1 ##

[0016] The relationship between f _S and f _M and f _L are present applicant are described in detail in Japanese Patent Application No. Hei 1-165656 filed.

The output signal of the sample-and-hold (S / H) 1220 is sent to a low-pass filter 1230 to extract a fundamental wave component, converted to a rectangular wave by a comparator 1240, and the converted signal is sent to a counter 1180. The counter 1180 outputs a comparison signal f _R (f _R is the same frequency as f _L ) obtained by further dividing the output signal of the second frequency divider 1130 to 1 / n by the third frequency divider 1140. ) And the reference signal f _S from the crystal oscillator 1100 are input. Therefore, the counter 1180 opens the gate by the comparison signal f _R and closes the gate by the signal from the comparator 1240. While the gate is open, the counter 1180 counts the reference signal f _S from the crystal oscillator 1100. It is like.

The arithmetic circuit 1500 includes a counter 11
The configuration is such that the phase difference between the comparison signal f _R and the signal from the comparator 1240 is calculated based on the counter value of 80. Then, the arithmetic circuit 1500 performs the same operation on the internal reference optical path inside the optical distance meter, and calculates the distance to the corner cube from the phase difference between the external distance measuring optical path and the internal reference optical path.

[0019]

However, in the above-described pulse-type lightwave distance meter, since the comparator 1240 is configured to detect the zero-cross point of the output of the low-pass filter 1230, only the zero-cross point becomes phase information. However, there is a problem that phase information of a portion other than the zero cross point is not used at all.

Further, the output signal f _{L of the} comparator 1240
Fluctuates due to the noise of the APD 71 and the amplifier 1160, and the fluctuations of the waveform shaping circuit 1170, the sample / hold (S / H) 1220, the low-pass filter 1230, the comparator 1240, and the like. Therefore, the comparison signal f _R
When the phase difference between the output signal f _L of the comparator 1240 and the output signal f _L of the comparator 1240 is very small, the output value of the counter 1180 is greatly different between the portions (a), (b) and (c) as shown in FIG. A phenomenon occurs. Therefore, there is a problem that the output value of the counter 1180 cannot be simply averaged within a certain time.

Further, between the lightwave distance meter and the corner cube, the light quantity of the received light pulse fluctuates due to air fluctuation and the like. The light amount of the received light pulse is
If the number 16 is out of the light amount range in which it operates properly, it is not possible to capture an accurate reception timing. The sample hold value at this time is defective data, and it is desirable not to use it. However, it is impossible to eliminate only defective data with analog data such as the low-pass filter 1230.

Further, a sample hold (S / H) 1220
In order to extract the fundamental wave component of the step-like waveform from the step-like waveform by using the low-pass filter 1230, the phase shift from the waveform to be measured is detected in order, and f such that the beat-down waveform is lined up neatly. There was a restriction that _M must be selected.

[0023]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned problems, and has a function of synchronizing a frequency signal to be measured repeated at a specific frequency with the frequency to be measured.
Timing signal generating means for generating a timing signal synchronized once every time, AD converting means for sampling and holding the frequency signal to be measured by the timing signal and performing AD conversion, and digital signal converted by the AD converting means. Memory means having n addresses for storing signals, addition means for adding data stored in the memory means and digital signal data converted by the AD conversion means, An arithmetic processing means for obtaining a fundamental wave component from the data of each address by Fourier transform and detecting the phase of the measured frequency signal from the fundamental wave component.

[0024]

Further, the present invention provides a timing signal generating means for generating a timing signal which is different from the frequency to be measured and which synchronizes once every n times, with respect to the frequency signal to be measured repeated at a specific frequency. AD for converting the frequency signal to be measured into an analog signal by a timing signal.
Conversion means, memory means having n addresses for storing the digital signal converted by the A / D conversion means, data stored in the memory means and A
Adding means for adding the digital signal data converted by the D converting means; and arithmetic processing means for detecting the phase of the frequency signal to be measured by Fourier transform from the data at each address of the memory means. When the phase shift of each of the timing signals with respect to the frequency signal to be measured is not 1 / n of the cycle of the frequency signal to be measured, the arithmetic processing means may store the data of each address of the memory means. Are arranged to reproduce similar data of the frequency signal to be measured, and to calculate a phase using this data. The distance measuring device according to the present invention includes a light source unit that emits light in a pulsed manner, an optical unit for transmitting light from the light source unit to the measurement target, and a light receiving unit that receives reflected light from the measurement target. A light receiving means for converting the received signal into a received pulse of an electric signal; and a timing for generating a timing signal which is different in synchronization from the received signal converted by the light receiving means and synchronized once every n times. Signal generating means;
A / D conversion means for sampling and holding the received signal in accordance with the timing signal and performing A / D conversion, a memory means having n addresses for storing the digital signal converted by the A / D conversion means, An adder for adding the stored data and the digital signal data converted by the AD converter, and a fundamental wave component obtained by Fourier transform from the data at each address of the memory, and An arithmetic processing means for detecting the phase of the reception signal and calculating the distance to the object to be measured based on the phase difference from the light emission from the light source unit to the reception signal.

The distance measuring apparatus according to the present invention comprises a light source unit which emits light in a pulsed manner, optical means for transmitting light from the light source unit to an object to be measured, and reflected light from the object to be measured. And a timing signal synchronizing with the received signal converted by the light receiving device and synchronizing once every n times with respect to the received signal converted by the light receiving device. Signal generating means for converting the received signal into a digital signal using the timing signal, and n for storing the digital signal converted by the AD converting means.
Memory means having a plurality of addresses; addition means for adding data stored in the memory means and the digital signal data converted by the AD conversion means;
From the data of each address of the memory means, the phase of the received signal is detected by Fourier transform, and the distance to the object to be measured is calculated based on the phase difference from the light emission from the light source to the received signal. And arithmetic processing means.

The distance measuring apparatus according to the present invention also includes a light source unit that emits light in a pulsed manner, optical means for transmitting light from the light source unit to the object to be measured, and reflected light from the object to be measured. And a timing signal synchronizing with the received signal converted by the light receiving device and synchronizing once every n times with respect to the received signal converted by the light receiving device. Signal generating means for converting the received signal into an analog-to-digital signal using the timing signal, and memory means having n addresses for storing the digital signal converted by the analog-to-digital converting means. Adding means for adding the data stored in the memory means and the digital signal data converted by the A / D converting means; From the data of the dress, the phase of the received signal is detected by Fourier transform, and based on the phase difference from the light emission from the light source unit to the received signal, based on arithmetic processing means for calculating the distance to the object to be measured. The arithmetic processing means rearranges the data of each address of the memory means when the phase shift of each of the timing signals with respect to the received signal is not 1 / n of the cycle of the received signal. Thus, similar data of the received signal is reproduced, and the phase is calculated using this data.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention constructed as described above
The timing signal generating means generates a timing signal which is different from the measured frequency and is synchronized once every n times with respect to the measured frequency signal which is repeated at a specific frequency.
The D conversion means samples and holds the frequency signal to be measured based on the timing signal and performs AD conversion, and the memory means having n addresses stores the digital signal converted by the AD conversion means. And adding means for adding the data stored in the memory means and the digital signal data converted by the AD converting means,
The arithmetic processing means obtains a fundamental wave component from the data of each address of the memory means by Fourier transform, detects the phase of the measured frequency signal from the fundamental wave component, and calculates the phase of the timing signal with respect to the measured frequency signal. If the deviation is not 1 / n of the period of the frequency signal to be measured,
By rearranging the data of each address of the memory means, similar data of the frequency signal to be measured is reproduced, and the phase is calculated using this data.

[0028]

Further, in the distance measuring device according to the present invention, the light source unit emits a pulse, the optical unit sends out the light from the light source unit to the object to be measured, and the light receiving unit reflects the light from the object to be measured. It receives light and converts it into a received electrical signal. The timing signal generating means generates a timing signal which is different in synchronization from the received signal and is synchronized once every n times, and the AD converting means AD-converts the received signal based on the timing signal, and a memory means having n addresses Stores the digital signal converted by the AD conversion means. Then, the adding means adds the data stored in the memory means and the digital signal data converted by the AD converting means, and the arithmetic processing means calculates the phase of the received signal from the data of each address of the memory means by Fourier transform. While detecting, the phase shift of each phase of the timing signal with respect to the received signal is 1 / n of the receiving cycle
If not, the data of each address of the memory means is rearranged to reproduce similar data of the received signal, and the phase is calculated using this data. The arithmetic processing means calculates the distance to the object to be measured based on the phase difference between the light emission from the light source unit and the received signal.

[0030]

An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 2, the optical distance meter according to the present embodiment includes a laser diode 1, a condenser lens 2, a condenser lens 3, and a pair of split prisms 41 and 42.
, Optical path switching chopper 5, internal optical path 6, APD
71, an optical fiber 8 for delay, a prism 9, and an objective lens 10. The corner cube 11 corresponds to an object to be measured arranged at a position distant from the main unit of the electro-optical distance meter, and has a function of reflecting an optical pulse.

Laser diode 1 and condenser lens 2
1, 22, light emitting side optical fiber 81, and split prism 41
, The prism 9 and the objective lens 10 correspond to optical means.

The laser diode 1 corresponds to a light source unit. The laser diode 1 of this embodiment employs a pulse laser diode, has a relatively large peak power, and has a duty ratio of about 0.01%. Waves can be generated. The optical path switching chopper 5 switches light beams. The light receiving element 7 corresponds to light receiving means, and any element that can receive the pulse light emitted from the laser diode 1 is sufficient.

The delay optical fiber 8 is one of optical delay means, and it is desirable to use a GI fiber as the delay optical fiber 8 in order to prevent mode dispersion.

The split prism 41 is composed of a first half mirror 411 and a second half mirror 412, and the split prism 42 is composed of a first half mirror 421 and a second half mirror 422. I have. The light emitting side optical fiber 81 and the delay optical fiber 8 are connected between the laser diode 1 side and the splitting prism 41. Furthermore, the splitting prism 42 and the light receiving element 7 side are connected by a light receiving side optical fiber 82. In this embodiment, a part of the light emitting side optical fiber 81 is replaced with the delay optical fiber 8.
It is configured to also serve as

When a light emission pulse is emitted from the laser diode 1, the light emission pulse is coupled to the input end 81 a of the light emitting side optical fiber 81 by the condenser lenses 21 and 22. Since the light emitting side optical fiber 81 is connected to the delay optical fiber 8, the light pulse travels in the delay optical fiber 8 and is sent to the split prism 41. The pulse train transmitted through the first half mirror 411 of the split prism 41 can be emitted to the external distance measuring optical path via the optical path switching chopper 5. The pulse reflected by the first half mirror 411 of the split prism 41 and further reflected by the second half mirror 412 passes through the optical path switching chopper 5,
The light can be emitted to the internal distance measuring optical path 6. The optical path switching chopper 5 is for switching between the internal ranging optical path 6 and the external ranging optical path. Therefore, when the light path switching chopper 5 selects the external distance measuring light path, the light pulse is reflected by the prism 9 and then emitted to the outside by the objective lens 10.

The pulse emitted from the objective lens 10 is
The light is reflected by the corner cube 11, received by the objective lens 10 again, and sent to the prism 9. The received pulse train is reflected by the prism 9 and sent to the splitting prism 42, and the received pulse light transmitted through the first half mirror 421 of the splitting prism 42 is coupled to the light receiving end 82 a of the light receiving side optical fiber 82.

When the optical path switching chopper 5 selects the internal distance measuring optical path 6, the light emission pulse is sent to the split prism 42 through the internal distance measuring optical path 6. The light pulse is reflected by the first half mirror 421 and the second half mirror 422 built in the split prism 42 and is coupled to the light receiving end 82 a of the light receiving side optical fiber 82.

The exit end 8 of the light receiving side optical fiber 82
The light pulse emitted from 2b is
It is designed to bind to APD71 by 1, 32,
The light is converted into a current pulse by the light receiving element 7.

Next, the configuration of the electric circuit of this embodiment will be described in detail.

The first embodiment shown in FIG.
0, the first frequency divider 110, the synthesizer 120, and the second
Frequency divider 130, laser diode 1, laser diode driver 150, APD 71, amplifier 160, waveform shaping circuit 170, counter 180, peak hold circuit 190, level determination circuit 200, band pass filter 210, and sample hold (S / H). ) 220 and a phase measuring device 10000. The phase measuring device 10000 includes an AD converter 300 and a memory 400.
And a CPU 500.

The crystal oscillator 100 is one of the reference signal generating means.
One, and the is generating the reference signal f _S. This reference signal is supplied to a first frequency divider 110, a synthesizer 120, a bandpass filter 210, and a counter 180. The reference signal supplied to the first frequency divider 110 is
The frequency is divided by the first frequency divider 110 into 1 / (n−1) and sent to the synthesizer 120. Synthesizer 120
Multiplies the signal supplied from the first frequency divider 110 by n,
The signal is sent to the second frequency divider 130. The second frequency divider 130 divides the signal supplied from the synthesizer 120 by 1 / m to generate a measurement signal f _M. The output signals of the first frequency divider 110, the second frequency divider 130, and the synthesizer 120 are binarized signals.

Then, the laser diode driver 150
Is the measurement signal f _M which is the output signal of the second frequency divider 130
, The laser diode 1 is driven in a pulsed manner.

The measurement signal f _M, which is the output signal of the second frequency divider 130, is also supplied to the CPU 500, the counter 180, and the peak hold 190. Measurement signal f _M
Becomes a light emission confirmation signal to the CPU 500, and becomes a reset signal to the counter 180 and the peak hold 190.

The light pulse emitted from the laser diode 1 passes through the optical system and is received by the APD 71. The APD 71 is one of the light receiving elements 7, and is a diode that can apply a deep bias to a pn junction to induce a nasal multiplication and obtain a gain. The APD 71 receives an optical pulse that has passed through the internal reference optical path and an optical pulse that has passed through the external ranging optical path. The APD 71 converts the light pulse into an electric signal of a current pulse train and sends the electric signal to the amplifier 160.

The amplifier 160 amplifies the signal input from the APD 71. The output signal of the amplifier 160 is converted into binary digital data by the waveform shaping circuit 170, and is converted by the counter 180 and the sample hold (S
/ H) 220 and the AD converter 300.

F _S sent from the crystal oscillator 100 to the band-pass filter 210 becomes a sine wave and is sent to the sample and hold circuit 220. Sample hold circuit 220
Samples and holds the sine wave by the signal of the waveform shaping circuit 170. The held value is sent to an AD converter 300 and AD-converted. The converted digital data is stored in a predetermined memory 400.

The signal sent from the amplifier 160 to the peak hold circuit 190 is peak-held by the peak hold circuit 190, becomes a DC level signal corresponding to the peak value of the pulse light, and is sent to the level determination circuit 200. The level determination circuit 200 receives a signal from the peak hold circuit 190, determines whether the light amount of the light receiving pulse train is within a range in which the APD 71 and the amplifier 160 operate properly, and sends the result to the CPU 500. . CPU5
00 receives a signal from the level determination circuit 200 and adopts data from the AD converter 300 only when the light amount of the light receiving pulse train is an appropriate value.

Next, f _S = 15 MHz, n = 101,
The phase relationship when m = 5000 will be described.

The values of m dash, f _M , and f _L and their phase relations can be obtained from (Equation 2) by calculating (n-1).

[0051]

(Equation 5)

Is as follows.

Further, the frequency f _{M of the} pulse train is expressed by “Equation 1”.
Than,

[0054]

(Equation 6)

At this time, the phase relationship between the frequency f _M of the received pulse train and the frequency f _S of the sine wave from the band-pass filter 210 is expressed by Equation 3.

[0056]

(Equation 7)

Thus, the light emission pulses have the same phase relationship again 101 times, shifted by the value of “Equation 7”. This frequency is obtained from “Equation 4”.

[0058]

(Equation 8)

Is as follows.

That is, 1 sent from the crystal oscillator 100
5 MHz is passed through the band-pass filter 210, and the sine wave obtained by
Hz deviates little by little. For this reason, the phase relationship between the reception timing signal and the sine wave obtained through the band-pass filter 210 also slightly deviates.

Each light emission pulse train and the bandpass filter 2
The phase relationship with the sine-wave sine-wave signal obtained through 10 is a phase relationship in which 101 cycles constitute one cycle.
The second light emission pulse train has the same phase relationship as the first light emission pulse train. Therefore, the sample hold (S /
H) The output signal of 220 is

F = 3030 Hz / 101 = 30 Hz

Thus, one cycle is completed.

This situation will be described in detail with reference to FIG. FIG. 3A shows a band pass filter 210.
5 shows the order of the phase shift of the pulse train of the frequency f _M with respect to the frequency f _S of the sine wave signal from FIG. FIG.
(B) shows the relationship between the frequency f _S of the sine wave signal from the band-pass filter 210 and the frequency f _M of the received pulse train, and further shows the stepped frequency f _L output from the sample-and-hold circuit 220. It shows a waveform.

As described above, the sample hold circuit 220
Is repeated at the frequency f _L and is composed of n hold values. Therefore, the memory 400 has n
More storage capacity is required. The memory 400 is configured such that the address is incremented by the CPU 500 for each light emission pulse, and the AD converted data is sequentially stored in the memory 400 via the CPU 500.

The memory 400 and the CPU 500 also have a function of an adding means, and add the stored data at an arbitrary address on the memory 400 and the AD-converted data.
It can be stored on the memory 400 again. Since the data after the (n + 1) -th time has the same phase relationship as the first cycle, if the judgment of the level judgment circuit 200 is appropriate,
The accuracy of the AD conversion data can be improved by adding the data of the previous cycle and performing the averaging process later.

That is, the sample hold (S / H) 220
Is one cycle at 30 Hz and does not become a sine wave, but by performing rearrangement at the stage of storing in the memory 400 after AD conversion, AD conversion data having a sine wave shape can be created. In other words, if it is not 1 / n of the period of the received signal, the data of each address of the memory means can be rearranged to reproduce similar data of the received signal.

Further, the data that has been sample-holded and A / D-converted by the light emission pulse trains after the 102nd time are:
Since the data after the second cycle of 30 Hz is obtained, if the determination result of the level determination circuit 200 is appropriate, the data is added to the data of the cycle up to the previous cycle, and the data is averaged to perform A
The accuracy of the D conversion data can be improved.

Next, a method of calculating the phase from the data stored in the memory 400 will be described. In the data stored in the memory 400, the horizontal axis of the waveform of f _{L in} FIG. 3B corresponds to the address of the memory 400, and the vertical axis of the waveform of f _L indicates the data value at that address. It has become equivalent.

The waveform of f _{L in} FIG. 3B is obtained from the sine wave from the band-pass filter 210, and the phase shift order of the pulse train of the frequency f _M with respect to the sine wave f _S is also known. Thus, by rearranging the addresses of the memory 400, the sine wave can be restored.
The restored sine wave is as shown in FIG.
The phase θ ₀ of the sine wave waveform is obtained by converting each data of the sine wave waveform to D ₀
(I)

[0071]

(Equation 9)

[0072]

(Equation 10)

[0073]

[Equation 11]

Can be obtained as (However, i
= 1 to n)

This operation is performed by the sample and hold circuit 220
This is equivalent to obtaining the phase of the fundamental wave component of the waveform of f _L from the waveform of frequency f _L output from the waveform by Fourier transform.

The above operation is performed by the memory 400 and the CPU 500.
Can be performed. Therefore, the phase measuring device 10
000 is an AD converter 300, a memory 400, and a CP.
U500.

The laser diode 1 executed as described above
From the emission of light to the storage of the AD-converted data in the memory 400 are performed for the external distance measuring optical path and the internal reference optical path. And AD conversion data by the internal reference optical path;
The phase difference φ between the two waveforms from the AD conversion data of the external distance measuring optical path corresponds to the optical path difference.

That is, assuming that the phase of the external distance measuring optical path is θ ₀ and the phase of the internal reference optical path is θ ₁ , the distance from the optical distance meter to the corner cube as the object to be measured is:

[0079]

(Equation 12)

Is obtained. Here, C is the speed of light.

The precision measurement distance L obtained in this manner is obtained by enlarging the time axis of the reference frequency f _S of the crystal oscillator 100,
The phase is obtained by Fourier transform. Therefore,

(C / f _S ) * (1/2)

The distance is defined as one cycle. Therefore, when f _S is a 15 MHz, 1 cycle 10
m.

The coarse measurement distance can also be determined with an accuracy of 10 m from the counter value of the counter 180 in the external distance measuring optical path. That is, the counter 180 sets the reference frequency f _S of the crystal oscillator 100 to the second frequency divider 130.
From the signal of the waveform shaping circuit 170 to the signal of the waveform shaping circuit 170. Then, the count value is sent to the CPU 500, and a coarse measurement distance can be obtained from the difference between the count value of the external ranging optical path and the count value of the internal reference optical path.

By combining the coarse measurement distance and the precision measurement distance, the actual distance from the optical distance meter to the object to be measured can be obtained. A configuration for performing these operations corresponds to a distance measuring unit.

Note that the precise measurement distance is obtained by performing a Fourier transform on the AD-converted data value to obtain the phase of the fundamental wave component. Therefore, the waveform to be sampled and held does not necessarily have to be a sine wave. It may be a wave or a triangular wave. Similarly, a low-pass filter can be employed instead of the band-pass filter 210.

The present invention can be applied not only to the pulse type light wave distance meter, but also to the phase measurement of a continuous modulation type light wave distance meter using a conventional LED.

[0088]

According to the present invention having the above-described structure, a timing signal for synchronizing with a frequency signal to be measured which is repeated at a specific frequency and which is different from the frequency to be measured and synchronized once every n times is generated. Signal generating means, AD converting means for sampling and holding the frequency signal under measurement in accordance with the timing signal, and performing AD conversion.
Memory means having n addresses for storing the digital signal converted by the conversion means, and addition for adding the data stored in the memory means and the digital signal data converted by the AD conversion means Means, from the data of each address of the memory means, a fundamental wave component is obtained by Fourier transform, and the arithmetic processing means for detecting the phase of the frequency signal to be measured from the fundamental wave component. The averaging effect of the phase measurement is high, and there is an effect that a malfunction does not occur even when the phase difference between the waveform to be measured and the comparison signal is small as in the phase comparison by the comparator.

Further, since the AD-converted data is stored in the memory, each waveform data can be processed individually, so that the degree of freedom of data acquisition is high.
Since the data on the memory can be freely rearranged, there is no need to convert the m dash of "Equation 2" to an integer value,
There is an effect that the dividing ratio of the dividing period can be optimized on a circuit.

The distance measuring device using this phase measuring device has an excellent effect that it can remove defective data due to air fluctuations and the like and can perform extremely accurate distance measurement.

[0091]

[Brief description of the drawings]

FIG. 1 is a diagram showing an electrical configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an optical configuration according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating waveforms of f _S , f _M , and f _{L according to} the present embodiment.

FIG. 4 is a diagram illustrating a waveform restored by rearranging in the embodiment.

FIG. 5 is a diagram illustrating a conventional technique.

FIG. 6 is a diagram illustrating a problem of the conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser diode 2 condenser lens 3 condenser lens 41 split prism 42 split prism 5 optical path switching chopper 71 APD 8 delay optical fiber 9 prism 10 objective lens 11 corner cube 160 amplifier 170 waveform shaping circuit 180 counter 190 peak hold circuit 200 level determination circuit 220 Sample hold circuit 300 AD converter 400 Memory 500 CPU 10000 Phase measurement device

(Equation 12)

Continued on the front page (72) Inventor Masaaki Yabe 75-1, Hasunumacho, Itabashi-ku, Tokyo Inside Topcon Corporation (72) Inventor Yasutaka Katayama 75-1, Hasunumacho, Itabashi-ku, Tokyo Topcon Corporation (72) Invention Kazushige Koshikawa 75-1, Hasunuma-cho, Itabashi-ku, Tokyo Inside Topcon Corporation (56) References JP-A-2-77673 (JP, A) JP-A-1-213592 (JP, A) JP-A-3- 289584 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /48-7/51 G01S 17/00-17/95

Claims (4)

(57) [Claims] 1. A timing signal generating means for generating a timing signal which is different in synchronization with a frequency to be measured which is repeated at a specific frequency and which synchronizes once every n times, with this timing signal A / D conversion means for sampling and holding and AD converting the frequency signal to be measured, memory means having n addresses for storing the digital signal converted by the AD conversion means, and stored in the memory means. Means for adding the converted data and the digital signal data converted by the A / D conversion means, and a fundamental wave component by Fourier transform from the data at each address of the memory means.
And a calculation processing means for detecting the phase of the frequency signal to be measured from the fundamental wave component . 2. A frequency signal under test repeated at a specific frequency.
Signal and the measured frequency are different in synchronization,
Timing to generate timing signals that synchronize once
Signal generation means and the timing signal.
AD conversion means for AD converting the measurement frequency signal;
The digital signal converted by the AD conversion means is recorded.
Memory means having n addresses for storing
The data stored in the memory means and the A / D conversion means
To add the converted digital signal data
Means for adding the data of each address of the memory means
From the Fourier transform, the phase of the measured frequency signal is
It consists of arithmetic processing means for detection.
The arithmetic processing means is configured to calculate the tie for the frequency signal to be measured.
The deviation of each phase of the
If it is not 1 / n of the period, each address of the memory means
By rearranging the data of the
Reproduce similar data of several signals and use this data
A position characterized by being configured to calculate a phase
Phase measurement device. 3. A light source unit that emits light in a pulsed manner, and the light source
Optical hand for transmitting light from the part to the measurement object
And the reflected light from the object to be measured
Receiving means for converting the received pulse into
Synchronize with the received signal converted by the stage
Is different, and a timing signal synchronized once every n times is generated.
Timing signal generating means for causing
Samples and holds more the received signal into a signal AD conversion
Conversion means for performing the conversion and the conversion by the A / D conversion means.
N addresses for storing the converted digital signal.
Memory means having a memory and a memory stored in the memory means.
Data and digital data converted by the AD conversion means.
Addition means for adding signal data, and the memory
From the data at each address of the means by Fourier transform
The main wave component is obtained, and the order of the received signal is calculated from the fundamental wave component.
Phase from the light emission from the light source to the received signal.
Calculates the distance to the measurement target based on the phase difference at
And arithmetic processing means for
Distance measuring device. 4. A light source unit that emits light in a pulsed manner, and the light source
Optical hand for transmitting light from the part to the measurement object
And the reflected light from the object to be measured
Receiving means for converting the received pulse into
Synchronize with the received signal converted by the stage
Is different, and a timing signal synchronized once every n times is generated.
Timing signal generating means for causing
-To-digital conversion for AD-converting the received signal with a signal
Means and a digital signal converted by the AD conversion means.
Memory device with n addresses for storing signals
And the data stored in the memory means and the AD conversion.
Digital signal data converted by the conversion means
Adding means for performing
From the data, the phase of the received signal is calculated by Fourier transform.
Detecting the light emission from the light source unit to the reception signal.
To calculate the distance to the measurement target based on the phase difference
Arithmetic processing means.
Is each phase of the timing signal with respect to the received signal
Is not 1 / n of the period of the received signal,
Rearranges data at each address of the memory means.
By reproducing similar data of the received signal,
It is configured to calculate the phase using the data of
A distance measuring device characterized by the above-mentioned.