JP2003270346A - Pulse signal generation circuit and distance ranging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse signal generation circuit with generated pulse signal timing free of influence of fluctuation in an input signal amplitude and to provide a ranging device capable of measuring a distance with high precision. <P>SOLUTION: After laser pulse light is radiated to a measurement object, reflected pulse light is received and its light receipt signal is used as an input signal S105. In formation of a receipt timing signal, a signal S401 formed by delaying the input signal S105 by a half width equivalent by means of a delay 401 is outputted, a signal S402 formed by delaying the input signal S105 by a double of the half width is outputted, an intersection of an output level between the input signal S105 and the signal S401 is detected for forming a front side edge of the receipt timing signal 106, and an intersection of an output level between the signal S401 and the signal S402 is detected for forming a back side edge of the receipt timing signal 106. Time measurement is started by irradiation with the laser pulse light, the time measurement is stopped by the receipt timing signal 106, and from the obtained light travel time, a distance to the measurement object is found. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse signal generation circuit for generating a pulse signal corresponding to an input signal, and
The present invention relates to a distance measuring device that uses this pulse signal generation circuit to measure the distance to an object to be measured using light.

[0002]

2. Description of the Related Art A distance measuring device used in a general surveying instrument has an accuracy of 5 mm + 3 in a range of 1 m to several km.
It is necessary to measure with high accuracy of ppm × D (D is a distance to be measured). Fluctuations in the received signal amplitude can be cited as a factor that deteriorates this accuracy. As a method for absorbing this fluctuation, there is signal detection by a differentiating circuit. When the pulsed reception signal is passed through a differentiating circuit with optimized constants, an output signal whose sign is inverted at the timing of the peak of the pulse is obtained. Even if the amplitude of the pulse changes, the timing of the peak position does not change. Therefore, by detecting the zero cross of the output of the differentiating circuit, it is possible to detect the timing that is less affected by the amplitude fluctuation.

[0003]

However, it is difficult to optimize the constants of the differentiating circuit in the method using the differentiating circuit.
Even if it is optimized for a single device, there is a problem in that there is a large difference in pulse width depending on the device. Therefore, if all the devices are optimized with the same constant, the influence of the timing deviation due to the amplitude variation becomes large.

The present invention provides a pulse signal generation circuit in which the timing of the generated pulse signal is not affected by fluctuations in the amplitude of the input signal, and also provides a distance measuring device that enables highly accurate distance measurement. .

[0005]

A first aspect of the present invention is applied to a pulse signal generating circuit for generating a pulse signal corresponding to an input signal, wherein the input signal has a value within a signal width of the input signal. And a first delay means for delaying the output signal to output a first delay signal and an input signal having a signal width of 2
A second delay means for delaying a second time, which is a value within twice the first time and outputting a second delay signal, and an input signal, a first delay signal, and a second delay signal. Based on this, the intersection of the output levels of the input signal and the first delay signal is detected to generate the front edge of the pulse signal, and the intersection of the output levels of the first delay signal and the second delay signal is detected to generate the pulse. And an intersection point detecting means for generating a pulse signal by generating a trailing edge of the signal. According to a second aspect of the present invention, in the pulse signal generating circuit according to the first aspect, the intersection detecting means outputs the first signal as active when it detects that the input signal is equal to or higher than a predetermined level. Comparator means and an enable signal when the first signal is activated, and when the enable signal is enabled and the level of the input signal is lower than the level of the first delayed signal, the second signal is output as active. A second comparator means and a third comparator which is enabled when the second signal is activated, and which is third when the level of the first delayed signal is higher than the level of the second delayed signal when enabled. A third signal is activated when the level of the first delayed signal is lower than the level of the second delayed signal.
And a third comparator means for inverting the signal and outputting the signal, and the third signal output by the third comparator means is a pulse signal. The invention of claim 3 is the pulse signal generating circuit according to claim 1 or 2, wherein
The time of 1 corresponds to the pulse width at the value of about half the amplitude of the input signal, and the second time corresponds to about twice the pulse width at the value of about half the amplitude of the input signal.
According to a fourth aspect of the present invention, in the pulse signal generation circuit according to any one of the first to third aspects, the intersection point detecting means is ECL.
The device further comprises conversion means for converting the pulse signal output from the ECL device from the ECL level to the TTL level by using the device. The invention of claim 5 is
A light sending unit that sends the distance measuring light to the target object based on the distance measurement command signal, a light receiving unit that receives the distance measuring light reflected by the target object and outputs a light receiving signal, and a light receiving signal Based on the time measurement end signal generating means for generating a time measurement end signal based on the distance measurement command signal, the time measurement is ended based on the time measurement end signal, and the light traveling time from light transmission to light reception is determined. It is applied to a distance measuring device provided with a time measuring means for measuring and a light traveling time measured by the time measuring means, and a calculating means for calculating a distance to a target object based on the obtained light traveling time. The measurement end signal generation means includes the pulse signal generation circuit according to any one of claims 1 to 4, an input signal of the pulse signal generation circuit corresponds to a light reception signal, and a pulse signal of the pulse signal generation circuit measures time. End Which corresponds to the issue. Claim 6
The present invention comprises the distance measuring device according to the fifth aspect.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a distance measuring device that is an embodiment of the present invention. The distance measuring device according to the present embodiment measures the distance to a measurement target (target) using pulsed light. This distance measuring device is particularly provided in a surveying instrument that measures the distance to the measurement object, the angle in the direction of the measurement object, and the like.

The operation control unit 1 composed of a CPU, etc.,
According to the measurement command signal from the operator or the like, the time measuring unit 2
A distance measurement command signal S101 is given to. The time measuring unit 2 gives a pulse emission command S102 to the light transmitting unit 3 and starts time measurement. The time measuring unit 2 includes a counter that counts a reference clock from the start to the end of time measurement,
It has an integration circuit (not shown) that interpolates the time between reference clocks. The integrator circuit, between the reference clock,
It outputs a voltage signal according to the elapsed time. Precise time is measured by a combination of these counters and an integrating circuit.

The light transmitting section 3 includes, for example, a semiconductor laser driving circuit 31, a semiconductor laser 32, and the emitted pulsed light 10.
It has a light transmitting optical system 33 for transmitting the light. Light transmitting optical system 33
Inside, the pulsed light 103 is transmitted to the distance measuring optical path 11 which is an external optical path.
There is provided an optical path splitting section 34 that splits the optical path into 0 and the reference optical path 111 which is an internal optical path. The optical path splitting unit 34 is provided with the optical path splitting unit 34 including, for example, a semi-transmissive mirror arranged at 45 ° in the incident optical path of the pulsed light 103. Therefore, the pulsed light 103 is the pulsed light 104 emitted to the distance measuring optical path 110 and the pulsed light 10 emitted to the reference optical path 111.
It is divided into 5.

An optical path switching unit 36 is provided in the light transmitting optical system 33, and a distance measuring optical path 110 or a reference optical path 11 is generated by a switching signal (not shown) from the arithmetic control unit 1.
Shield one of the two. When the reference optical path 111 is shielded and the pulsed light is projected from the distance measuring optical path 110, the reflected pulsed light 106 reflected by the object to be measured and returning from the distance measuring optical path 110 is received by the light receiving optical unit in the light receiving unit 4. System 41a
Is incident on. Pulsed light 1 incident on the light receiving optical system 41a
06 is focused on the light receiving element 42 such as an APD (avalanche photodiode) via the light amount adjustment filter 44 and the light receiving optical system 41b, and photoelectrically converted.

On the other hand, when the distance measuring optical path 110 is shielded, the reference pulsed light 105 is sent to the reference optical path 111,
The light amount is attenuated to a predetermined level by the neutral density filter 35, and the light receiving optical system 4 in the light receiving unit 4 is passed through the light amount adjusting filter 44.
It reaches 1b. The light receiving optical system 41b is 4
The reference pulsed light 1 is provided with a semi-transmissive mirror 43 arranged at 5 °.
05 is also guided to the same optical axis as the reflected pulsed light 106, condensed on the light receiving element 42, and photoelectrically converted.

The received pulse signal S which is the output of the APD 42
104 is amplified by the signal amplification unit 5, and the amplified reception pulse signal S105 is supplied to the reception timing detection unit 6. The reception timing detector 6 includes a comparator 6
1 and the level conversion unit 62, the reception timing signal S106 that is stable in time is output to the time measurement unit 2 even when the amplitude varies with respect to the input reception pulse signal S105. The detailed operation of the reception timing detection unit 6 will be described later.

The time measuring unit 2 uses the pulse emission command S102.
To the reception timing signal S106 (pulse light traveling time) is measured, and time data S112 is sent to the arithmetic control unit 1. The arithmetic control unit 1 calculates the distance to the object to be measured based on the time data S112 and the speed of light.

FIG. 2 is a diagram for explaining a distance measuring method by the apparatus of FIG. (1) and (2) of FIG.
The relationship between the pulse emission command S102 and the reception timing signal S106 when 1 is selected is shown. Further, (3) and (4) show the relationship between the pulse emission command S102 and the reception timing signal S106 when the distance measuring optical path 110 is selected.

Returning to FIG. 1, the actual distance measuring sequence will be described. The arithmetic control unit 1 confirms the level of the received signal from the distance measuring optical path 110 before measuring the distance (light quantity balance processing). First, the arithmetic control unit 1 minimizes the gain of the amplification unit 5 based on the gain control signal S108, and the drive signal S
The light amount adjusting filter 44 is driven by the driving unit 45 by the 109.
Are set so that both the reference optical path 111 and the distance measuring optical path 110 have maximum transmittance. The light amount adjustment filter 44 is divided into a part through which light of the reference optical path 111 passes and a part through which light of the distance measuring optical path 110 passes for one filter. The light on the distance optical path 110 remains open and does not change, and when the light on the distance measuring optical path 110 is attenuated, the light on the reference optical path 111 remains open and does not change.

Next, the optical path switching unit 36 is moved to the reference optical path 11
The first side is opened, and the arithmetic control unit 1 outputs the output S105 of the amplification unit 5.
The reception level signal S107 obtained by peak-holding the signal is read. At this time, the reception level S107 of the reference optical path 111 is adjusted in advance by the neutral density filter 35 so as to be a predetermined level. Next, the optical path switching unit 36 is opened on the side of the distance measuring optical path 110, and the received signal level from the object to be measured is similarly measured by reading S107.

When the received signal level from the object to be measured is higher than the signal level of the reference optical path 111, the light quantity of the distance measuring optical path 110 of the light quantity adjusting filter 44 is attenuated via the drive signal S109 and the drive section 45. And adjust so that the signal levels of the two optical paths are equal. If the received signal level from the DUT is lower than the signal level of the reference optical path 111, the gain control signal S108
The gain of the amplifying section 5 is increased via to make the received signal level from the DUT equal to the signal level of the reference optical path 111. In this case, since the signal level of the reference optical path 111 is increased by increasing the gain of the amplifier 5, the drive signal S
The light amount of the reference optical path 111 of the light amount adjusting filter 44 is attenuated via the 109 and the drive unit 45, and the signal levels of the two optical paths are adjusted to be equal. The arithmetic control unit 1 is 2
After the signal levels of the two optical paths become equal, the distance measuring operation starts.

The optical path switching unit 36 opens the side of the reference optical path 111 and sends the pulsed light 103 to the reference optical path 111. The reference pulse light 105 attenuated to a predetermined light amount by the neutral density filter 35 passes through the light receiving section 4, the amplifying section 5, and the reception timing detecting section 6 to the time measuring section 2 and receives the reception timing signal S1.
Sent as 06. As described above, the time measuring unit 2 receives the reception timing signal S106 from the pulse emission command S102.
Up to S112, and the arithmetic control unit 1 obtains the measurement distance Lref on the reference optical path 111 based on the measurement time S112 and the speed of light.

Next, the distance measuring optical path 11 is measured by the optical path switching unit 36.
The 0 side is opened and the pulsed light 103 is sent to the distance measuring optical path 110. The reflected pulsed light 106 reflected by the object to be measured returns through the distance measuring optical path 110, is detected by the light receiving section 4, and the reception timing signal S106 is sent to the time measuring section 2 as in the case of the reference optical path, and the arithmetic control section 1 Measuring distance L in the optical path
s is required. The arithmetic control unit 1 subtracts the measurement distance Lref in the reference optical path from the measurement distance Ls in the distance measuring optical path to cancel the error factor due to the fluctuation due to the temperature of the electric system circuit and the accurate distance to the object to be measured. Calculate L.

FIG. 3 is a diagram showing details of the structures of the distance measuring optical path 110, the reference optical path 111, the light transmitting section 3 and the light receiving section 4 in the distance measuring apparatus of the present embodiment shown in FIG.
The pulsed light emitted by the semiconductor laser 32 becomes a parallel light flux by the collimator lens 301, and the semi-transmissive prism 302
It is incident on (corresponding to the optical path splitting unit 34). The semi-transmissive prism 302 has, for example, a transmission T: reflection R ratio of T: R = 1: 9.
The reference pulsed light having the characteristics of 9 and sent to the reference optical path 111 side is greatly attenuated.

The reference optical path 111 is controlled by the optical path switching unit 36.
When is selected, the reference pulsed light is reflected by the mirror 31.
The light is reflected at 3, and the neutral density filter 35 and the light amount adjustment filter 44
Through the semi-transmissive prism 311 (corresponding to the semi-transmissive mirror 43)
Incident on. The reference pulsed light is reflected by the semi-transmissive prism 311, and then received by the APD 42 via the relay lens 312.

On the other hand, when the distance measuring optical path 110 is selected by the optical path switching unit 36, the semi-transmissive prism 30
The pulsed light reflected by 2 and sent to the distance measuring optical path 110 side is directed to the object to be measured through the collimator lens 304, the mirror 305, and the objective lens 306.
It is sent as 04. The reflected pulsed light 106 reflected by the measurement object and returned is received by the objective lens 306 and passes through the dichroic mirror 307 to the optical fiber 3.
It is incident on 09.

The above dichroic mirror 307 has a characteristic of reflecting infrared light and transmitting visible light. The reflected pulsed light 106 incident on the optical fiber 309 is reflected by the collimator lens 310 arranged at the other end of the optical fiber 309.
After being collimated by the light source, the light amount adjusting filter 44 attenuates the light amount to the same amount as the reference pulse light passing through the reference optical path, is reflected by the mirror 317, and is received by the APD 42 via the semi-transmissive prism 311 and the collimator lens 312. .

Here, the light quantity adjusting filter 44 is a disk-shaped filter whose transmittance gradually changes at a predetermined gradient in the circumferential direction at the passage position of the reference pulse light and the distance measuring pulse light, and its center Drive unit (drive motor)
It is rotationally driven at 45. Further, the reference pulse light passing position and the distance measuring pulse light passing position on the filter are on the circumferences of different radii, and the transmittance of the distance measuring optical path at the position where the density gradient of the reference optical path gradually changes. Is constant at the maximum, and conversely, the transmittance of the reference optical path is constant at the maximum at the position where the density gradient of the distance measuring optical path gradually changes.

FIG. 3 further shows a collimation optical system for aligning the optical axes of the light-transmitting and light-receiving optical systems in the direction of the object to be measured. That is, with respect to the operator 321, the eyepiece lens 320, the reticle 319, and the erecting prism 31.
8, the focusing lens 308 and the objective lens 306 constitute a collimation optical system. Dichroic mirror 307
It has the property of transmitting visible light. In this embodiment, the collimating optical system, the light transmitting optical system, and the light receiving optical system are all configured on the same optical axis.

Next, details of the reception timing detector 6 according to the present embodiment will be described with reference to the block diagram of FIG. 4 and the timing chart of FIG. FIG. 4 is a block diagram of the reception timing detection unit 6. FIG. 5 is a timing chart in the block diagram of FIG. The comparator section 61 at the front stage in FIG. 4 includes two delays (delay elements) 401 and 402 and three comparators 40.
3, 404, 405. Delay 401, 4
02 uses a passive delay line including a coil and a capacitor. In addition, you may make it use other delay elements, such as an active delay line.

For higher accuracy, it is desirable that the pulse width of the input pulse signal is narrower, and when the pulse width is 10 ns or less, it is desirable to use the ECL type comparator. This configuration example is based on the premise that an ECL type comparator is used, and therefore the output signal is T
A level conversion unit 62 for converting to a TL level is connected.

Next, the operation of the comparator section 61 will be described. When the reception pulse signal S105 is input to the comparator 403, the output S403 is output to the comparator 404 when the signal level exceeds a predetermined threshold, and the comparator 404 changes from the latch mode to the comparator mode by this signal, Output S40 at the same time
4 changes from level H to level L. The latch mode is a mode for holding the output state, and the comparator mode is a mode for performing a comparator operation. In other words, when the output S403 becomes active (level H), the comparator 404 is enabled and performs the comparator operation.

S401 of the two inputs of the comparator 404 is a signal obtained by delaying S105 by a delay 401 by about a half-value width of the pulse (a pulse width at a value of about half the amplitude), and the two signals are the crosspoints. The magnitude relationship is reversed at the timing, and the output S404 changes from the level L to the level H at this timing.

The comparator 405 changes from the latch mode to the comparator mode by the rising edge of the output S404, and at the same time, the output S405 changes from the level L to the level H. S402 of the inputs of the comparator 405 is a signal obtained by delaying S105 by a delay 402 set to a delay time which is approximately twice the delay time of the delay 401, and the two inputs S401 and S402 are at the cross point timing. The magnitude relationship is reversed, and the output S
405 changes from level H to level L at this timing.

The output S403 changes from the level H to the level L when the received pulse signal S105 becomes smaller than a predetermined threshold. However, this predetermined threshold may be set to a value that is sufficiently smaller than the level at which the cross point fluctuates.

From the above, as shown in FIG. 5, the output S405 of the comparator 405 is the original pulse signal S105.
On the other hand, the logic signal is inverted by two cross points generated by the pulse signals delayed by two delays having different delay times. That is, the original pulse signal S
The front edge of the active pulse signal of the output S405 is generated at a point (intersection) where 105 and the level of the output S401 intersect, and after the active pulse signal of the output S405 at a point (intersection) where the levels of the output S401 and the output S402 intersect. Side edges are generated. The active pulse signal of this output S405 becomes the reception timing signal S106.

Here, the reason why the reception timing signal S106 is generated by the cross points in the present embodiment will be described. FIG. 6 is a diagram showing changes in the reception timing when the reception pulse signal is detected at a certain threshold level. It can be seen that when the amplitude of the reception pulse signal changes from the amplitude level of the solid line to the levels of the upper and lower broken lines due to temperature and other environmental changes, the reception timing signal fluctuates back and forth by δt as shown in FIG. If this signal is used as it is as a reception timing signal, the reception timing fluctuates and accurate measurement cannot be achieved. Therefore, in the present embodiment, as a method for absorbing this fluctuation, a pulse signal is generated by cross points.

Consider, for example, the comparator 404 as an example. In FIG. 7, the received pulse signal S105 and the received pulse S105 input to the comparator 404 are delayed 401.
It is a figure which shows the signal waveform of the signal S401 delayed by. As shown in FIG. 6, the received pulse signal S105 and the signal S401
It can be seen that the timing of the cross point does not change even if the amplitude of f changes. This makes it possible to acquire the timing that is not affected by the environmental change.

If the rear edge of the reception timing can be generated by one cross point, highly accurate measurement is possible if the rear edge is used as a reference for time measurement. However, in the present embodiment, as described above, the ECL type is used for the comparator and its output signal is TT.
A level conversion unit 62 for converting to L level (or CMOS level) is used. FIG. 8 is an example of a circuit for converting the ECL level to the TTL level. In this level conversion circuit, the input pulse is affected by the base capacitance of the transistor, and when the input pulse width changes, the delay time of the rear edge changes.

For example, it may be assumed that the output S404 of the comparator 404 of FIG. 4 is used as it is as the reception timing signal S106 via the level conversion circuit 62. In such a case, since the rear edge of the output S404 is generated by the cross point, it is generated at a timing that does not change, but the front edge changes due to the influence of the amplitude of the pulse signal S105. That is, in the output S404, the timing of the rear edge is not changed, but the pulse width is changed. When such a varying pulse width is input to the level converting unit 62, the final TTL is obtained even if the cross point does not change with respect to the amplitude variation.
The timing of the trailing edge of the output signal will change.

Therefore, in the present embodiment, as described above, the timing is generated by the cross points at both the front edge and the rear edge of the reception timing signal so that the pulse width does not change. ing. As a result, even when the level conversion circuit as shown in FIG. 8 is used, the timing-stable reception timing signal S106 can be output.

As described above, the reception timing signal S10 is stable in timing even if the amplitude of the reception signal fluctuates.
6 can be generated, which in turn enables accurate distance measurement. Further, as compared with the case of using a differentiating circuit, it is less affected by variations in circuit constants, selection of components is facilitated, and the manufacturing process is facilitated. As a result, parts cost and manufacturing cost are also reduced.

In the above embodiment, an example of the distance measuring device in the surveying instrument has been described, but the present invention is not limited to this. When the pulse signal corresponding to the input signal is generated, the present invention can be applied to any application that needs to generate the pulse signal at a timing that is not affected by the fluctuation of the amplitude of the input signal. Further, the distance measuring device need not be limited to the one mounted on the surveying instrument. For example,
It can also be used in a device for measuring the distance between vehicles. That is, it can be applied to any application in which the distance to the target object needs to be measured.

In the above-described embodiment, the signal S105 is delayed by the delay 401 by the half-value width of the pulse (pulse width at about half the amplitude), and the signal S105 is further delayed.
In the above description, the delay 402 is delayed by twice the full width at half maximum of the pulse. However, the invention is not limited to this. The value may be varied within the pulse width of the signal S105 within a range in which the cross point can be detected.

In the above embodiment, the signal S105 is input to the delay 401 and the delay 402, and the delay 402 is set to a delay value which is about twice the delay 401. However, the present invention is not limited to this. do not have to. The delay 401 and the delay 402 may have the same delay value, and the output of the delay 401 may be input to the delay 402.

In the above embodiment, the comparator 40
Although the example in which the ECL element is used is described in Nos. 3 to 405, it is not necessary to limit to this content. It may be an element of another technology such as TTL or CMOS. The present invention can be applied even when the level conversion circuit is not used.

In the above-mentioned embodiment, the example of the pulsed laser light is explained, but it is not necessary to limit to this content. Any light may be used as long as it can be aimed and irradiated on the target object and can be received by the light receiving element when the light is reflected from the target object.

In the above embodiment, the case where the signal is at a high level with respect to the GND is active, that is, the so-called positive logic has been described, but the present invention is not limited to this.
It can also be applied to the case where a circuit or the like is configured by so-called negative logic, in which the GND level is activated with respect to a certain level of a signal. That is, in the present specification, the invention is represented by using positive logic for convenience of description, but the present invention includes those configured by both positive logic and negative logic.

In the above-described embodiment, an example in which a comparator is used to compare the levels of two inputs has been described, but the contents are not limited to this. That is, any circuit, element, or the like capable of comparing the levels of two inputs and outputting a signal according to the comparison result may be used. In this specification, these are referred to as comparator means.

In the present specification, "light transmission" means to emit light, to irradiate light, to emit light, and the like.

Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects that are conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention.

[0047]

Since the present invention is configured as described above, it is possible to generate a pulse signal corresponding to an input signal at a stable timing even if the amplitude of the input signal changes, for example. Become. Further, when such a pulse signal generation circuit is used in a distance measuring device, it becomes possible to perform distance measurement with high accuracy at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram of a distance measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a distance measuring method by the device of FIG.

FIG. 3 is a diagram showing details of configurations of a distance measuring optical path, a reference optical path, a light transmitting section, and a light receiving section.

FIG. 4 is a block diagram of a reception timing detection unit.

5 is a timing chart in the block diagram of FIG.

FIG. 6 is a diagram showing changes in reception timing when a reception pulse signal is detected at a certain threshold level.

FIG. 7 is a diagram showing signal waveforms of a reception pulse signal S105 and a signal S401 delayed by a delay.

FIG. 8 is an example of a circuit for converting an ECL level into a TTL level.

[Explanation of symbols]

1 Arithmetic control unit 2 hours measurement section 3 Light transmitter 4 Light receiving part 5 Signal amplifier 6 Reception timing detector 61 Comparator section 62 Level converter 401, 402 delay 403-405 comparator

Continued front page    (72) Inventor Hitoshi Shibuya             2-16-2 Minami Kamata, Ota-ku, Tokyo Stocks             Company Nikon Geotex F term (reference) 5J084 AA05 AD01 BA04 BA36 BB04                       BB14 BB21 BB31 BB38 CA12                       CA19 CA21 CA57 CA64 DA01                       DA08 EA04 EA31 EA33

Claims (6)

[Claims] 1. A pulse signal generation circuit for generating a pulse signal corresponding to an input signal, wherein the input signal is delayed by a first time, which is a value within a signal width of the input signal, and a first delay. A first delay means for outputting a signal, and delaying the input signal by a second time that is a value within twice the signal width of the input signal and is longer than the first time to generate a second delay signal. Output second delay means, and detecting an intersection of output levels of the input signal and the first delay signal based on the input signal, the first delay signal, and the second delay signal. An intersection point for generating a front edge of the pulse signal, detecting an intersection of output levels of the first delay signal and the second delay signal, and generating a rear edge of the pulse signal for generating the pulse signal A pulse signal, characterized by comprising: Generating circuit. 2. The pulse signal generating circuit according to claim 1, wherein the intersection detecting means outputs a first signal as active when it detects that the input signal is at a predetermined level or higher. Comparator means and enabled when the first signal is active, and activating the second signal when enabled and when the level of the input signal is lower than the level of the first delayed signal And a second comparator means for outputting the second delay signal when the second signal is activated, and the level of the first delay signal is higher than the level of the second delay signal when the second signal is active. When the level is high, the third signal is activated, and when the level of the first delayed signal is lower than the level of the second delayed signal, the third signal is activated. A pulse signal generation circuit, comprising: a third comparator means for inverting and outputting the third signal, wherein the third signal output by the third comparator means is the pulse signal. 3. The pulse signal generation circuit according to claim 1, wherein the first time corresponds to a pulse width at a value of about half the amplitude of the input signal, and the second time corresponds to the input signal. A pulse signal generation circuit corresponding to about twice the pulse width at a value of about half the amplitude of the pulse signal. 4. The pulse signal generation circuit according to claim 1, wherein the intersection detecting means uses an ECL element, and the pulse signal output from the ECL element is changed from an ECL level to a TTL level. A pulse signal generation circuit further comprising conversion means for converting to. 5. A light sending means for sending a distance measuring light toward a target object based on a distance measuring command signal, and a light receiving signal for receiving the distance measuring light reflected by the target object and outputting a light receiving signal. A light receiving means, a time measurement end signal generating means for generating a time measurement end signal based on the light reception signal, and a time measurement start based on the distance measurement command signal, and a time measurement end based on the time measurement end signal, A time measuring unit that measures a light traveling time from the light transmission to the light reception, and a light traveling time measured by the time measuring unit is acquired, and a distance to the target object is calculated based on the acquired light traveling time. A distance measuring device comprising: a calculating means for performing the time measurement end signal generating means, the pulse signal generating circuit according to any one of claims 1 to 4, wherein the input signal of the pulse signal generating circuit is The above Corresponding to the optical signal, the pulse signal of the pulse signal generating circuit is a distance measuring device, characterized in that it corresponds to the time measurement completion signal. 6. A surveying instrument comprising the distance measuring device according to claim 5.