CN211528690U

CN211528690U - Distance measuring device of single optical path system

Info

Publication number: CN211528690U
Application number: CN201922044649.4U
Authority: CN
Inventors: 黄耀勇
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2020-09-18
Anticipated expiration: 2029-11-22

Abstract

The application relates to a distance measuring device of a single optical path system, which comprises a signal generating module, a distance measuring module and a distance measuring module, wherein the signal generating module is used for generating a first electric signal and a second electric signal; the signal transmitting module is connected with the signal generating module and used for converting the first electric signal into an optical signal after compensation processing, and transmitting the optical signal and the compensated first electric signal to the signal receiving module; the signal receiving module is respectively connected with the signal generating module and the signal transmitting module and is used for receiving the second electric signal, the first electric signal and the reflected signal of the optical signal, forming a first mixing signal according to the reflected signal and the second electric signal and forming a second mixing signal according to the first electric signal and the second electric signal; the signal processing module is connected with the signal receiving module and used for processing the received first mixing signal and the second mixing signal to output the measured distance. This range unit is through carrying out compensation processing to first signal of telecommunication, can eliminate the influence of temperature variation, improves the stability and the precision of measuring result.

Description

Distance measuring device of single optical path system

Technical Field

The application relates to the technical field of photoelectric distance measurement, in particular to a distance measuring device of a single optical path system.

Background

The laser ranging is widely applied to the fields of laser radars, building construction, industrial sensors and the like. The laser distance measuring instrument has high requirements on measuring precision, so the complexity of a circuit and the requirements of precision devices are greatly improved. The influence of environmental factors such as temperature and device lifetime on the device performance, in turn, causes the phase shift generated by the device, which is not negligible.

Taking the phase type measurement as an example, conventionally, two light emitting devices (such as laser diodes) of a dual optical path system are limited by an optical path, a certain distance exists between installation positions, heat dissipation spaces around the light emitting devices are different, and a large temperature difference generally exists, so that equivalent resistances of the two light emitting devices are different, and thus, a distance measurement result changes along with the change of temperature, and meanwhile, the defects of complexity, large structure volume and the like of an optical system also exist. In the single-light-path system, because only one light-emitting unit is provided, the driving circuit is asymmetric, the light-emitting unit is very sensitive to temperature, the change range of the impedance value of the light-emitting unit is large, the load impedance of the driving circuit is changed, and the static working point of the driving circuit is changed along with the change of the load impedance, so that the phase and the time delay of signals are changed. Therefore, the traditional distance measuring device with double optical paths and single optical path systems cannot eliminate the additional phase shift and time delay of the circuit system, and the measuring result has large change along with the temperature and poor precision within the working temperature range.

SUMMERY OF THE UTILITY MODEL

The application provides a single optical path system's range unit can eliminate the influence of operating temperature's change to range unit measuring result, improves measuring result's stability and precision.

A ranging apparatus of a single optical path system, the apparatus comprising: the device comprises a signal generating module, a signal transmitting module, a signal receiving module and a signal processing module;

the signal generating module is used for generating a first electrical signal and a second electrical signal, transmitting the first electrical signal to the signal transmitting module and transmitting the second electrical signal to the signal receiving module;

the signal transmitting module is connected with the signal generating module and used for converting the first electric signal into an optical signal after compensation processing, and transmitting the optical signal and the compensated first electric signal to the signal receiving module;

the signal receiving module is respectively connected with the signal generating module and the signal transmitting module, and is configured to receive a reflected signal of the optical signal, the second electrical signal, and the first electrical signal, and form a first mixed signal according to the reflected signal and the second electrical signal, and form a second mixed signal according to the first electrical signal and the second electrical signal;

the signal processing module is connected with the signal receiving module and is used for processing the received first mixing signal and the second mixing signal to output a measurement distance.

In one embodiment, the signal transmitting module includes a driving unit, a light emitting unit, and a first compensating unit;

the first electric signal is transmitted to the signal receiving module through the driving unit and the light emitting unit to form a first path; the first electric signal is transmitted to the signal receiving module through the driving unit to form a second path;

the driving unit is respectively connected with the signal generating module, the first compensating unit, the light emitting unit and the signal receiving module, and is used for receiving the first electric signal, conducting with the light emitting unit on the first path, and conducting with the first compensating unit on the second path;

the light emitting unit is connected with the signal receiving module and used for generating an optical signal according to the first electric signal and transmitting the optical signal to the signal receiving module;

the first compensation unit is connected with the signal receiving module and used for performing compensation processing on the first electric signal.

In an embodiment, the first compensation unit includes a capacitor, a resistor, a laser diode, or a circuit having an equivalent resistance value equal to that of the light emitting unit, and is configured to compensate for the impedance of the second path so that the impedances of the first and second paths are the same.

In one embodiment, the device further comprises a second compensation unit, a third compensation unit, a first switch unit and a second switch unit;

the first switch unit is respectively connected with the driving unit, the second switch unit and the second compensation unit and is used for conducting a path between the driving unit and the second compensation unit in the first path and conducting a path between the driving unit and the second switch unit in the second path;

the second switch unit is respectively connected with the third compensation unit and the signal receiving module, and is configured to switch on a path between the signal receiving module and the third compensation unit in the first path, and switch on a path between the signal receiving module and the first switch unit in the second path.

In an embodiment, further comprising a third switching unit, the driving unit comprising a first driving unit and a second driving unit; wherein:

the first driving unit is connected with the first compensation unit, and the second driving unit is connected with the light emitting unit;

the third switching unit is respectively connected with the signal generating module, the first driving unit and the second driving unit, and is configured to conduct a path between the signal generating module and the second driving unit in the first path and conduct a path between the signal generating module and the first driving unit in the second path.

In one embodiment, the first compensation unit includes a feedback circuit and a compensation resistor;

wherein: the compensation resistor is connected with the first driving unit and used for compensating the access impedance value of the first driving unit;

the feedback circuit is respectively connected with the output end of the first driving unit, the output end of the second driving unit and the compensation resistor, and is used for adjusting the resistance value of the compensation resistor according to the impedance value of the light-emitting unit so as to enable the resistance value of the compensation resistor to be equal to the equivalent resistance value of the light-emitting unit.

wherein: the compensation resistor is connected with the driving unit and used for compensating the access impedance value of the driving unit;

the feedback circuit is respectively connected with the output end of the driving unit and the compensation resistor and is used for adjusting the resistance value of the compensation resistor according to the equivalent resistance value of the light-emitting unit so as to enable the resistance value of the compensation resistor to be equal to the equivalent resistance value of the light-emitting unit.

In an embodiment, the device further comprises a fourth compensation unit; the third switching unit includes a fourth switch and a fifth switch; wherein:

the fourth switch is respectively connected with the signal generation module and the first driving unit and is used for conducting a path between the signal generation module and the first driving unit when the second path is established;

the fifth switch is respectively connected with the signal generation module and the second driving unit and is used for conducting a path between the signal generation module and the second driving unit when the first path is formed;

the fourth compensation unit is respectively connected with the fourth switch and the fifth switch, and is used for accessing the fourth switch on the first path and accessing the fifth switch on the second path.

In one embodiment, the signal receiving module includes a photoelectric conversion unit and a mixing unit;

the photoelectric conversion unit is used for converting the optical signal into a third electric signal;

the frequency mixing unit is respectively connected with the photoelectric conversion unit and the signal generating module, and is used for mixing the second electric signal and the third electric signal to form the first mixed signal; and is further configured to mix the first and second electrical signals to form the second mixed signal.

In one embodiment, the signal processing module comprises a filtering and amplifying unit, an analyzing unit and a signal processing unit;

the filtering and amplifying unit is connected with the signal receiving module and is used for filtering and amplifying the first mixing signal and the second mixing signal;

the analysis unit is connected with the filtering and amplifying unit and is used for performing frequency discrimination or time discrimination analysis on the first mixed signal and the second mixed signal after filtering and amplifying so as to output a phase difference or a time difference between the first mixed signal and the second mixed signal;

the signal processing unit is connected with the analysis unit and used for processing the received phase difference or the time difference so as to output a measurement distance.

The distance measuring device provided by the embodiment of the application comprises a signal generating module, a signal transmitting module, a signal receiving module and a signal processing module; the signal generating module is used for generating a first electric signal and a second electric signal, transmitting the first electric signal to the signal transmitting module and transmitting the second electric signal to the signal receiving module; the signal transmitting module is connected with the signal generating module and used for converting the first electric signal into an optical signal, compensating the first electric signal and transmitting the optical signal and the compensated first electric signal to the signal receiving module; the signal receiving module is respectively connected with the signal generating module and the signal transmitting module, and is configured to receive the second electrical signal, the first electrical signal, and a reflected signal of the optical signal, and form a first mixed signal according to the reflected signal and the second electrical signal, and form a second mixed signal according to the first electrical signal and the second electrical signal; the signal processing module is connected with the signal receiving module and is used for processing the received first mixing signal and the second mixing signal to output a measurement distance. This range unit is through carrying out compensation processing to first signal of telecommunication, can eliminate the influence of temperature variation to range unit internal circuit system, improves the stability and the precision of measuring result.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a distance measuring device according to an embodiment;

FIG. 2 is a schematic block diagram of a ranging device according to an embodiment;

fig. 3 is a second schematic structural diagram of a distance measuring device according to an embodiment;

FIG. 4 is a junction diagram of the first path of FIG. 3 according to one embodiment;

FIG. 5 is a junction diagram of the second path of FIG. 3 according to one embodiment;

fig. 6 is a third schematic structural diagram of a distance measuring device according to an embodiment;

FIG. 7 is a fourth schematic structural diagram of a distance measuring device according to an embodiment;

fig. 8 is a fifth schematic structural view of a distance measuring device according to an embodiment;

FIG. 9 is a sixth schematic structural view of a distance measuring device according to an embodiment;

fig. 10 is a seventh schematic structural diagram of a distance measuring device according to an embodiment;

fig. 11 is an eighth schematic structural diagram of a distance measuring device according to an embodiment;

FIG. 12 is a ninth schematic view illustrating a structure of a distance measuring device according to an embodiment;

fig. 13 is an eleventh schematic structural diagram of a distance measuring device according to an embodiment.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to provide a thorough understanding of the present application, and in the accompanying drawings, preferred embodiments of the present application are set forth. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the specific embodiments disclosed below.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In the description of the present application, "a number" means at least one, such as one, two, etc., unless specifically limited otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Fig. 1 is a block diagram of a distance measuring device of a single optical path system according to an embodiment, and as shown in fig. 1, the distance measuring device includes: a signal generating module 100, a signal transmitting module 200, a signal receiving module 300 and a signal processing module 400; wherein:

the signal generating module 100 is configured to generate a first electrical signal and a second electrical signal, transmit the first electrical signal to the signal transmitting module 200, and transmit the second electrical signal to the signal receiving module 300.

In one embodiment, the first electrical signal may be a continuous signal, such as a sine signal, a cosine signal, etc., and the signal generating module 100 may be an oscillator, a Phase Locked Loop (PLL), a Direct Digital Synthesizer (DDS), or other signal generating modules 100 that generate a same frequency and have a fixed Phase difference. The second electrical signal is an electrical signal having a fixed frequency difference with the first electrical signal, and the second electrical signal is a continuous signal. And when the first electric signal is a continuous signal, ranging is carried out by adopting a phase ranging principle.

In one embodiment, the first electrical signal may be a pulse signal, and the signal generating module 100 may be a pulse generating device and other signal generating modules 100 having a fixed time difference with the trigger pulse. When the first electric signal is a pulse signal, the distance measurement is carried out by adopting a pulse distance measurement principle.

The signal transmitting module 200 is connected to the signal generating module 100, and is configured to perform compensation processing on the first electrical signal, convert the first electrical signal into an optical signal, and transmit the optical signal and the compensated first electrical signal to the signal receiving module;

in this embodiment, the first path is a path through which the first electrical signal is converted into an optical signal and then transmitted to the signal receiving module 300, and the second path is a path through which the first electrical signal is directly transmitted to the signal receiving module 300. The signal transmitting module 200 receives the first electrical signal generated by the signal generating module 100, converts the first electrical signal into an optical signal in a first path, transmits the optical signal to a target object to be detected to obtain a reflected signal, and reflects the reflected signal to the signal receiving module 300. The signal transmitting module 200 performs compensation processing on the first electrical signal in the second path, and then outputs the first electrical signal to the signal receiving module 300.

Because the first path and the second path are not symmetrical (unbalanced), the signals (the first electrical signal and the reflected signal) output to the signal receiving module 300 are different not only because the reflected signal is the first electrical signal passing through the target object to be measured, but also because a part of the difference is caused by the asymmetry of the electronic circuit inside the ranging apparatus, which may cause the inaccuracy of the ranging result. In the embodiment, the first electrical signal is compensated to eliminate phase shift or time delay difference caused by the inside of an electronic circuit, so that the measurement result is more accurate.

The signal receiving module 300 is respectively connected to the signal generating module 100 and the signal transmitting module 200, and is configured to receive the second electrical signal, the first electrical signal, and a reflected signal of the optical signal, and form a first mixed signal according to the reflected signal and the second electrical signal, and form a second mixed signal according to the first electrical signal and the second electrical signal.

The signal processing module 400 is connected to the signal receiving module 300, and is configured to process the received first mixing signal and the second mixing signal to output a measured distance.

The distance measuring device provided by the embodiment includes a signal generating module 100, configured to generate a first electrical signal and a second electrical signal; the signal transmitting module 200 is connected to the signal generating module 100, and is configured to convert the first electrical signal into an optical signal, perform compensation processing on the first electrical signal, and transmit the optical signal and the compensated first electrical signal to the signal receiving module 300; the signal receiving module 300 is respectively connected to the signal generating module 100 and the signal transmitting module 200, and is configured to receive the second electrical signal, the first electrical signal, and the reflected signal of the optical signal, and form a first mixed signal according to the reflected signal and the second electrical signal, and form a second mixed signal according to the first electrical signal and the second electrical signal; the signal processing module 400 is connected to the signal receiving module 300, and is configured to process the received first mixing signal and the second mixing signal to output a measured distance. The distance measuring device carries out compensation processing on the first electric signal, thereby eliminating the influence of temperature change on an internal circuit system of the distance measuring device and improving the stability and the precision of a measuring result.

In one embodiment, as shown in fig. 1, the signal transmitting module 200 includes a driving unit 201, a light emitting unit 202, and a first compensating unit 203;

the driving unit 201 is connected to the signal generating module 100, the first compensating unit 203, the light emitting unit 202 and the signal receiving module 300, respectively, and is configured to receive a first electrical signal, and is conducted to the light emitting unit 202 on a first path and is conducted to the first compensating unit 203 on a second path;

the light emitting unit 202 is connected to the signal receiving module 300, and is configured to generate an optical signal according to the first electrical signal and transmit the optical signal to the signal receiving module 300;

the first compensation unit 203 is connected to the signal receiving module 300, and is configured to perform compensation processing on the first electrical signal.

After receiving the first electrical signal transmitted by the signal generating module 100, the driving unit 201 selectively outputs the first electrical signal to the light emitting unit 202 or the signal receiving module 300, when the driving unit 201 is conducted with the light emitting unit 202, the driving unit 201 drives the light emitting unit 202 to emit light, the light emitting unit 202 converts the first electrical signal into an optical signal to be emitted to a target object to be detected to obtain an emitted signal, and the reflected signal is transmitted to the signal receiving module 300.

In an embodiment, the first compensation unit 203 includes a capacitor, a resistor, a laser diode, or a circuit having an equivalent impedance equal to that of the light emitting unit 202, and the embodiment of the first compensation unit 203 is not limited, and may be a single device or a circuit composed of a plurality of devices, and the equivalent resistance value of the first compensation unit 203 may be approximately equal to that of the light emitting unit 202.

In one embodiment, the driving unit 201 may be a transistor, a base of the transistor serves as an input terminal of the signal transmitting module 200, a collector of the transistor is electrically connected to the driving unit 201 and the light emitting unit 202, and an emitter of the transistor serves as an output terminal of the signal transmitting module 200. The light emitting unit 202 may be a light emitting device such as a laser diode or an LED, and may convert an electrical signal into an optical signal.

In one embodiment, the first electrical signal is transmitted to the signal receiving module 300 through the driving unit 201 and the light emitting unit 202 as a first path; the first electrical signal is transmitted to the signal receiving module 300 through the driving unit 201 as a second path;

the first compensation unit 203 is used for compensating the impedance of the second path so that the impedance of the first path and the impedance of the second path are the same. Each of the modules and units in the distance measuring device has a corresponding equivalent input impedance, and in this application, the input impedance of the signal generating module 100 is defined as Ze4 (i.e., the internal impedance of the signal source), the input impedance of the signal receiving module 300 is defined as Ze3, the input impedance of the driving unit 201 is defined as Ze2, and the input impedance of the light emitting unit 202 is defined as Ze 1. The impedance includes a resistive component and a reactive component. The reactance component is composed of parasitic capacitance and parasitic inductance of the device and the printed circuit board, and can be obtained by a measuring method under specific working frequency, and the reactance value under a certain working temperature is approximately substituted for the reactance value under the whole working temperature. The reactive parts of the subsequent embodiments are not shown for simplicity.

According to the method and the device, the first compensation unit is arranged on the first path, so that the external impedance of the driving unit 201 on the first path and the second path is unchanged, the phase or time delay change of signals passing through the first path and the second path is consistent, the signals are offset, and the distance measurement result is not influenced.

In one embodiment, as shown in fig. 2, the driving unit 201 has only one output terminal, and the output terminal of the driving unit 201 is connected to the first compensation unit 203 and the light emitting unit 202, respectively, for driving the first compensation unit 203 and the light emitting unit 202, respectively.

In an embodiment, the first compensation unit 203 includes a feedback circuit 2031, a compensation resistor 2032, and a sample-and-hold circuit 2033, and the sample-and-hold circuit 2033 is connected to the driving unit 201 and the feedback circuit 2031, respectively. One end of the compensation resistor 2032 is connected to a common terminal of the driving unit 201 and the light emitting unit 202, and the other end of the compensation resistor 2032 is connected to the feedback circuit 2031. When the first path operates, the sample hold circuit 2033 collects the voltage Vr of the drive unit and holds the output voltage Vrs, which is Vr. When the second path operates, the output voltage V0 of the feedback circuit 2031 ═ a (Vf-Vrs) adjusts the compensation resistance 2032 so that the equivalent input resistance of the compensation resistance follows the equivalent resistance of the light emitting unit 202. By adding the sample-and-hold unit 2033, the light emitting unit 202 can be turned off when the second path operates to save power consumption.

In an embodiment, as shown in fig. 3, the ranging compensation apparatus further includes a second compensation unit 204, a third compensation unit 205, a first switch 206 unit, and a second switch 207 unit;

the first switch 206 unit is respectively connected with the driving unit 201, the second switch 207 unit and the second compensation unit 204, and is used for conducting a path between the driving unit 201 and the second compensation unit 204 on a first path and conducting a path between the driving unit 201 and the second switch 207 unit on a second path;

the second switch 207 is connected to the third compensation unit 205 and the signal receiving module 300, respectively, for turning on a path between the signal receiving module 300 and the third compensation unit 205 in the first path. The second path turns on a path between the signal receiving module 300 and the first switch 206 unit. Specifically, in the first path, the first electrical signal is output to the signal receiving module 300 through the first path, and the driving unit 201 may selectively turn on the light emitting unit 202 through a switch. The first switch 206 is connected to the second compensation unit 204, and the second switch 207 is connected to the third compensation unit 205. Wherein the input impedance Ze3 'of the second compensation unit 204 is approximately equal to Ze3, and the input impedance Ze 2' of the third compensation unit 205 is approximately equal to Ze 2. The first electrical signal is output to the signal receiving module 300 through the second path, and the driving unit 201 can selectively turn on the first compensation unit 203 through a switch. The first switch 206 disconnects the second compensation unit 204, and the second switch 207 disconnects the third compensation unit 205, so that the first electrical signal is directly transmitted to the signal receiving module 300 through the driving unit 201.

Specifically, the first path is on, see fig. 4, and the second path is on, see fig. 5. The specific compensation principle is as follows: generally, signals are generated by the same device, the signal source internal resistances of the first path and the second path are equal, the light emitting unit emits light signals to the reflecting surface, the reflected signals are transmitted to the signal receiving module, although the light signals have influence on the equivalent impedance of the photoelectric conversion unit of the signal receiving module, a buffer circuit is arranged between the input end of the signal receiving module and the photoelectric conversion unit, and the equivalent input impedance of the signal receiving module is basically unchanged. When Ze1 ' ═ Ze1, Ze2 ' ═ Ze2, and Ze3 ' ═ Ze3, the time delay amount of the signal passing through the first path and the second path is equal to the phase shift amount, and the signal can be cancelled out, and the distance measurement result is not affected. Since the impedances Ze2 and Ze3 have small temperature sensitivity coefficients and the magnitudes are substantially constant in the whole operating temperature range, the compensation of the static operating points of the driving unit and the signal receiving module can be realized by using simple resistors. However, the light emitting unit is generally composed of a laser diode, and the required drive current varies greatly, corresponding to the variation in equivalent impedance, while maintaining the output optical power at different temperatures. Therefore, the light emitting unit as a load of the driving unit may affect a static operating point of the driving unit, and cause a phase shift amount and a time delay amount of a signal to change when the signal passes through the driving unit. In the second path, therefore, the first compensation unit is provided to offset the amount of phase shift and time delay caused by the light emitting unit in the first path.

In an embodiment, the first switch 206 and the second switch 207 comprise at least one device having a switching characteristic, such as an analog switch, a triode, a field effect transistor, a relay, and the like.

In an embodiment, as shown in fig. 6, the distance measuring device further includes a third switching unit 208, and the driving unit 201 includes a first driving unit 2011 and a second driving unit 2012; wherein:

the first driving unit 2011 is connected with the first compensation unit 203, and the second driving unit 2012 is connected with the light emitting unit 202;

the third switching unit 208 is respectively connected to the signal generating module 100, the first driving unit 2011 and the second driving unit 2012, and is configured to turn on a path between the signal generating module 100 and the second driving unit 2012 at the first path and turn on a path between the signal generating module 100 and the first driving unit 2011 at the second path.

The third switching unit 208 may be a transistor, an analog switch, etc., and the embodiment is not limited.

In one embodiment, as shown in fig. 7, the distance measuring device further includes a fourth compensation unit 209; the third switching unit 208 includes a fourth switch 2081 and a fifth switch 2082; wherein:

the fourth switch 2081 is connected to the signal generating module 100 and the first driving unit 2011, respectively, and is configured to conduct a path between the signal generating module 100 and the first driving unit 2011 in a second path;

the fifth switch 2082 is connected to the signal generating module 100 and the second driving unit 2012, respectively, and is configured to conduct a path between the signal generating module 100 and the second driving unit 2012 during the first path;

the fourth compensation unit 209 is connected to the fourth switch 2081 and the fifth switch 2082, respectively, and is configured to switch in the fourth switch 2081 in the first path and switch in the fifth switch 2082 in the second path.

The impedance value of the fourth compensation unit 209 is equal to Ze4, and is used to compensate the first drive unit 2011 and the second drive unit 2012, so that the impedances connected to the input terminals of the first drive unit 2011 and the second drive unit 2012 are equal. Specifically, when the signal generating module 100 is connected to the fifth switch 2082, the fourth switch 2081 is connected to the fourth compensation unit 209; when the signal generating module 100 connects the fourth switch 2081, the fifth switch 2082 connects the fourth compensation unit 209, so that the connected impedances of the fourth switch 2081 and the fifth switch 2082 are equal at any time.

In one embodiment, the first compensation unit includes a resistor having a resistance equal to an equivalent resistance of the light emitting unit at a certain temperature.

In one embodiment, the first compensation unit includes the same circuit as the light emitting unit.

In one embodiment, the first compensation unit 203 includes a circuit having the same equivalent impedance as the light emitting unit. As shown in fig. 8, the first compensation unit 203 includes a feedback circuit 2031 and a compensation resistor 2032; wherein:

the compensation resistor 2032 is connected to the first driving unit 2011 and is configured to compensate for an access impedance value of the first driving unit 2011;

the feedback circuit 2031 is connected to the output terminal of the first driving unit 2011, the output terminal of the second driving unit 2012, and the compensation resistor 2032, and is configured to adjust the resistance value of the compensation resistor 2032 according to the impedance value of the light emitting unit 202, so that the resistance value of the compensation resistor 2032 is equal to the equivalent resistance value of the light emitting unit 202, and the adjustment is continuous, and the resistance value of the compensation resistor 2032 follows the equivalent resistance value of the light emitting unit in real time, so that the impedances connected to the first driving unit 2011 and the second driving unit 2012 are equal, which not only eliminates the influence of the environment on the driving unit, but also eliminates the influence of other factors (such as device aging) on the light emitting unit, that is, the circuits of the first path and the second path are symmetrical, and avoids the influence of the internal circuit of the distance measuring apparatus on the measurement.

The principle is as follows: the light emitting unit 202 is typically a laser diode, and the resistance value of the laser diode is sensitive to temperature. When the temperature changes, the resistance value of the light emitting unit 202 changes, that is, Ze1 changes with the change of the temperature. When Ze1 changes, it causes a change in voltage Vr (Vr is proportional to the driving current or light power of light-emitting unit 202), which causes a change in the difference between Vf and Vr, further causing a change in V0. When the second path is on, second driving unit 2012 drives light emitting unit 202 to emit light, and at the same time, outputs voltage Vr (only at this time, second driving unit 2012 is disconnected from signal generating module 100, and no ac signal is input), and at the same time, first driving unit 2011 outputs voltage Vf, Vf that is proportional to the current flowing through compensating resistor 2032, Vo adjusts the compensating resistor, and feedback circuit 2031 may be an error amplifier.

In an embodiment, as shown in fig. 9, the first compensation unit 203 further includes a sample-and-hold circuit 2033, and the sample-and-hold circuit 2033 is connected to the second drive unit 2012 and the feedback circuit 2031 respectively. When the first path operates, the sample hold circuit 2033 collects the voltage Vr of the light emitting unit and holds the output voltage Vrs, which is Vr. When the second path operates, the output voltage V0 of the feedback circuit 2031 is a (Vf-Vrs) (a is a gain of the feedback circuit) to adjust the compensation resistance so that the equivalent resistance value of the compensation resistance follows the equivalent resistance value of the light emitting unit 202. By adding the sample-and-hold unit 2033, the light emitting unit 202 can be turned off when the second path operates to save power consumption.

In one embodiment, as shown in fig. 10, the compensation resistor is connected to the driving unit 201, the feedback circuit is connected to the driving unit 201 and the compensation resistor, respectively, and the sample-and-hold circuit is connected to the driving unit 201 and the feedback circuit, respectively. When the first path works, the sampling holding circuit collects the voltage Vr of the light-emitting unit and holds the output voltage Vrs, wherein Vrs is Vr. When the second path operates, the output voltage V0 of the feedback circuit 2031 is a (Vf-Vrs) (a is a gain of the feedback circuit) to adjust the compensation resistance so that the equivalent resistance value of the compensation resistance follows the equivalent resistance value of the light emitting unit 202.

In an embodiment, as shown in fig. 11, the first compensation unit 203 includes an analog-to-digital converter, a digital processor, and a compensation resistor, the analog-to-digital converter is connected to the first driving unit 2011, the second driving unit 2012, and the digital processor, and the compensation resistor is connected to the digital processor and the first driving unit 2011. The analog-to-digital converter and the digital processor form a feedback circuit, and when the first path is conducted, the digital processor samples the voltage Vr through the analog-to-digital converter (ADC), calculates the equivalent resistance value of the light-emitting unit 202 and stores the equivalent resistance value. When the second path is conducted, the digital processor adjusts the resistance value of the digital resistor to be equal to the resistance value stored in the first path. The equivalent resistance of the real-time dynamic follow-up light-emitting unit 202; or when the first path is conducted, the digital processor samples the voltage Vr through an analog-to-digital converter (ADC) and stores the voltage Vr. When the second path is turned on, the digital processor samples the voltage Vf through an analog-to-digital converter (ADC), calculates Vo Vf-Vr, and adjusts the resistance of the digital resistor according to Vo to be equal to the equivalent resistance of the light emitting unit 202. The real-time dynamic follows the equivalent resistance of the lighting unit 202.

It is understood that the compensation resistor 2032 may also be an analog resistor, and the analog resistor may be a transistor or other device or circuit capable of adjusting its equivalent resistance by analog signals. As shown in fig. 12, the signal output from the digital processor needs to be connected to an analog resistor through a digital-to-analog converter.

In one embodiment, as shown in fig. 13, the signal receiving module 300 includes a photoelectric conversion unit 301 and a mixing unit 302;

a photoelectric conversion unit 301 for converting the optical signal into a third electrical signal;

a frequency mixing unit 302, connected to the photoelectric conversion unit 301 and the signal generating module 100, for mixing the second electrical signal and the third electrical signal to form a first mixed signal; and the first and second electric signals are mixed to form a second mixed signal.

In one embodiment, the photoelectric conversion unit 301 may be an avalanche diode, a photodiode, a phototransistor, or a photomultiplier tube.

In an embodiment, the photoelectric conversion unit 301 and the mixing unit 302 may be regarded as a whole, and may be an avalanche diode, a photodiode, a phototriode, or a photomultiplier.

In an embodiment, the mixing unit 302 may output a circuit with a signal frequency equal to the sum, difference, or other combination of the two input signals. For example, the input signals have frequencies f₁And f₂After the mixing unit 302, the output signal may be f₁+f₂、f₁-f₂Or K₁f₁+K₂f₂Wherein, K is₁,K₂Is any natural number. The mixing unit 302 includes at least one device with mixing function, such as a diode, a triode, a mixing chip, etc.

In one embodiment, the signal processing module 400 includes a filtering and amplifying unit 401, an analyzing unit 402, and a signal processing unit 403;

a filtering and amplifying unit 401 connected to the signal receiving module 300, configured to perform filtering and amplifying processing on the first mixing signal and the second mixing signal;

an analyzing unit 402, connected to the filtering and amplifying unit 401, for performing frequency discrimination or time discrimination analysis on the filtered and amplified first mixed signal and second mixed signal to output a phase difference or a time difference between the first mixed signal and the second mixed signal;

and a signal processing unit 403 connected to the analyzing unit 402, for processing the received phase difference or time difference to output a measured distance.

The filtering and amplifying unit 401 performs filtering processing on the received signal to filter out high-frequency and/or low-frequency signals in the signal, and performs amplification processing on the filtered signal. The filtering and amplifying unit 401 may be composed of a filtering device and an amplifying device, or may be a device integrated together and having both filtering and amplifying functions.

In one embodiment, if the first electrical signal and the second electrical signal are both continuous signals, the analyzing unit 402 is a phase detector, where the phase detector in the signal processing module 400 is a circuit that makes the phase difference between the output signal and the first mixed signal and the second mixed signal have a certain relationship; if the first electrical signal and the second electrical signal are both pulse signals, the analyzing unit 402 is a time discriminator, wherein the time discriminator is a circuit that makes the output signal have a certain relationship with the time difference between the first mixed signal and the second mixed signal.

The signal processing unit 403 calculates a measurement distance from the phase difference or the time difference. When the signal processing unit 403 receives the phase difference, it can be according to the formula

Calculating the measurement distance, where f is the frequency of the signal, ▽ phi is the phase difference, c is the speed of light, when the time difference is received, according to the formula

The measured distance was calculated where c is the speed of light and ▽ T is the time difference.

The working principle of the distance measuring device provided by the embodiment of the application is briefly described as follows: based on the phase measurement method: the phase difference of the delayed signal transmission of the first path and the second path is set as theta₁And theta₂The additional phase shifts lagging the transmission through the electronics within the rangefinder are each ▽ theta₁And ▽ theta₂Then, the analysis result of the first mixing signal and the second mixing signal in the analysis unit 402 is:

Θ₁＝θ₁+▽θ₁

Θ₂＝θ₂+▽θ₂

since ▽ θ varies with the operating state of the measuring device and cannot be solved by precise calculation, the error generated by the measuring device can be eliminated by calculating the phase difference between the first mixing signal of the first path and the second mixing signal of the second path, that is, ▽ Θ is equal to Θ₁-Θ₂＝(θ₁-θ₂)+(▽θ₁-▽θ₂)。

When measuring distance, the distance measuring method is used for measuring distance by settingA compensation unit for ensuring the symmetry of the circuit inside the distance measuring device, so ▽ theta₁＝▽θ₂Then ▽ Θ is equal to Θ₁-Θ₂＝θ₁-θ₂In the embodiment of the present application, since the second path does not pass through the optical path, θ ₂0, ▽ Θ is equal to θ₁The above results have eliminated the effect of the additional phase shift instability, thus ensuring the accuracy of ranging.

In one embodiment, based on pulse measurements: let t be the time difference between the transmission of the signals of the first path and the second path₁And t₂The additional time lagged by the transmission through the electronic circuit inside the distance measuring device is ▽ t each₁And ▽ t₂Then, the analysis result of the first mixing signal and the second mixing signal in the analysis unit 402 is:

T₁＝t₁+▽t₁

T₂＝t₂+▽t₂

since ▽ T varies with the operating state of the measuring device and cannot be solved by precise calculation, the error generated by the measuring device can be eliminated by calculating the time difference between the first mixing signal of the first path and the second mixing signal of the second path, i.e. ▽ T-T₁-T₂＝(t₁-t₂)+(▽t₁-▽t₂)。

When the distance measuring device is used for measuring the distance, the first compensation unit is arranged, so that the symmetry of a circuit inside the distance measuring device is ensured, and ▽ t is obtained₁＝▽t₂Then ▽ T is equal to T₁-T₂＝t₁-t₂In the embodiment of the present application, since the second path does not pass through the optical path, t is₂0, ▽ T ═ T₁The above results already eliminate the effect of the instability of the additional time difference, thereby ensuring the accuracy of the distance measurement.

The ranging apparatus provided in the embodiment of the present application includes a signal generating module 100, a signal transmitting module 200, a signal receiving module 300, and a signal processing module 400; the signal generating module 100 is configured to generate a first electrical signal and a second electrical signal, transmit the first electrical signal to the signal transmitting module 200, and transmit the second electrical signal to the signal receiving module 300; the signal transmitting module 200 is connected to the signal generating module 100, and is configured to convert the first electrical signal into an optical signal in a time-sharing manner, perform compensation processing on the first electrical signal, and transmit the optical signal and the compensated first electrical signal to the signal receiving module 300; the signal receiving module 300 is respectively connected to the signal generating module 100 and the signal transmitting module 200, and is configured to receive the second electrical signal, the first electrical signal, and the reflected signal of the optical signal, and form a first mixed signal according to the reflected signal and the second electrical signal, and form a second mixed signal according to the first electrical signal and the second electrical signal; the signal processing module 400 is connected to the signal receiving module 300, and is configured to process the received first mixing signal and the second mixing signal to output a measured distance. The distance measuring device can eliminate the influence of temperature change through the compensation processing of the first electric signal, and the stability and the precision of a measuring result are improved.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A ranging apparatus for a single optical path system, the apparatus comprising: the device comprises a signal generating module, a signal transmitting module, a signal receiving module and a signal processing module;

2. The ranging apparatus as claimed in claim 1, wherein the signal transmitting module comprises a driving unit, a light emitting unit and a first compensating unit;

3. The distance measuring device of claim 2, wherein the first compensation unit comprises a capacitor, a resistor, a laser diode, or a circuit equal to an equivalent resistance value of the light emitting unit, for compensating the impedance of the second path so that the impedances of the first and second paths are the same.

4. The ranging apparatus as claimed in claim 2, further comprising a second compensation unit, a third compensation unit, a first switching unit and a second switching unit;

5. The ranging apparatus as claimed in claim 2, further comprising a third switching unit, the driving unit comprising a first driving unit and a second driving unit; wherein:

6. The ranging apparatus as claimed in claim 5, wherein the first compensation unit comprises a feedback circuit and a compensation resistor;

the feedback circuit is respectively connected with the output end of the first driving unit, the output end of the second driving unit and the compensation resistor, and is used for adjusting the resistance value of the compensation resistor according to the equivalent resistance value of the light-emitting unit, so that the resistance value of the compensation resistor is equal to the equivalent resistance value of the light-emitting unit.

7. The ranging apparatus as claimed in claim 2, wherein the first compensation unit comprises a feedback circuit and a compensation resistor;

the feedback circuit is respectively connected with the output end of the driving unit and the compensation resistor and is used for adjusting the resistance value of the compensation resistor according to the impedance value of the light-emitting unit so as to enable the resistance value of the compensation resistor to be equal to the equivalent resistance value of the light-emitting unit.

8. The ranging apparatus as claimed in claim 5, further comprising a fourth compensation unit; the third switching unit includes a fourth switch and a fifth switch; wherein:

9. The ranging apparatus according to claim 1, wherein the signal receiving module comprises a photoelectric conversion unit and a mixing unit;

10. The ranging apparatus as claimed in claim 1, wherein the signal processing module comprises a filtering amplifying unit, an analyzing unit and a signal processing unit;