CN109884644A - A kind of ultrasonic distance measurement chip - Google Patents
A kind of ultrasonic distance measurement chip Download PDFInfo
- Publication number
- CN109884644A CN109884644A CN201910278773.9A CN201910278773A CN109884644A CN 109884644 A CN109884644 A CN 109884644A CN 201910278773 A CN201910278773 A CN 201910278773A CN 109884644 A CN109884644 A CN 109884644A
- Authority
- CN
- China
- Prior art keywords
- circuit
- signal
- time gain
- distance measurement
- ultrasonic distance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 33
- 239000000523 sample Substances 0.000 claims description 9
- 230000005611 electricity Effects 0.000 claims description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000003466 welding Methods 0.000 abstract description 3
- 230000003321 amplification Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 238000003199 nucleic acid amplification method Methods 0.000 description 5
- 230000010355 oscillation Effects 0.000 description 3
- 210000001367 artery Anatomy 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 210000003462 vein Anatomy 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- VIKNJXKGJWUCNN-XGXHKTLJSA-N norethisterone Chemical compound O=C1CC[C@@H]2[C@H]3CC[C@](C)([C@](CC4)(O)C#C)[C@@H]4[C@@H]3CCC2=C1 VIKNJXKGJWUCNN-XGXHKTLJSA-N 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
Landscapes
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
This application discloses a kind of ultrasonic distance measurement chips, in order to solve the problems, such as to be unable to accurately control the gain of reflection signal and distinguish reflection signal and aftershock signal.Used technical solution is to be internally integrated logic control circuit and be connected to the ultrasonic wave transmitting circuit of logic control circuit, time gain module, amplitude to compare decision circuit, logic control circuit starts ultrasonic wave transmitting circuit according to the ranging trigger signal received, and time gain module to carry out dynamic gain to the reflection signal received at any time；Amplitude compares decision circuit and judges whether there is echo signal by comparing time gain module output valve and preset threshold, and can distinguish aftershock signal；It is one section of pulse width that logic control circuit, which will measure distance output according to echo signal,.The application reduces device and welding cost；Circuit board volume is reduced, it is highly beneficial to low-power dissipation system；Circuit board noise is reduced, remote weak reflection signals can be amplified, realize farther distance ranging.
Description
Technical field
This application involves ultrasonic measuring distance technology fields, and in particular to a kind of ultrasonic distance measurement chip.
Background technique
Ultrasonic distance measurement is a kind of non-contact detecting technology, is not influenced by light, measurand color etc., relatively severe
Environment (as contain dust) have certain adaptability, purposes extremely it is extensive.For example, measurement height, reversing radar, robot
The advantages of avoidance, unmanned plane avoidance, construction house etc., ultrasonic distance measuring apparatus is: instrument cost is lower than light wave rangefinder, laborsaving, behaviour
Facilitate.Since ultrasonic wave is easy to directional transmissions, good directionality, intensity is controlled well, its application value oneself by most attention.
Ultrasonic distance measurement refers to that spread speed and time calculate distance in air using sound wave.Pass through the ultrasound of transmission
The time difference that wave and receiving encounter between the reflected ultrasonic wave of barrier calculates module and arrives in conjunction with sound propagation velocity
The distance of front obstacle.
As shown in Figure 1, the method for most common supersonic sounding is ES Echo sounding, ultrasonic transmitter is sent out to a direction
Ultrasonic wave is penetrated, counter starts timing while emission time, and ultrasonic wave is propagated in air, encounters the resistance of obstacle object plane on the way
Gear just reflects immediately, and ultrasonic receiver receives the ultrasonic wave being reflected back and just stops timing immediately.Ultrasonic wave is in air
Spread speed be 340m/s, according to the time t of timer record, so that it may calculate distance s of the launch point away from obstacle object plane,
That is: s=340t/2.
There are two key technology points for ultrasonic distance measurement:
1. the amplitude of ultrasonic wave decays with the increase of distance, such short distance to reflect ultrasonic wave signal amplitude big,
It is small to reflect ultrasonic wave signal amplitude at a distance.Receiving end signal amplifier needs the gain of dynamic adjustment reflection signal, amplification
To the signal of suitable amplitude, comparator could correctly be told echo signal arrival time.
2. after ultrasonic wave transmitting probe has just emitted ultrasonic signal, receiving probe in a short time will receive transmitting terminal
Aftershock signal, how to distinguish reflection signal and aftershock signal at technological difficulties.
As shown in Fig. 2, existing ultrasonic distance measuring module is taken with discrete device, need multiple operational amplifiers with
And resistance capacitance does the amplification and shaping of analog signal, signal amplitude judgement, and it also requires single-chip microcontroller does logic control.Thus
At high cost, volume is big, and power consumption is high, is unfavorable for miniaturization and low power dissipation design.
For existing range finder module when receiving end signal amplifies, simple utilizes operational amplifier and resistance capacitance net
Network can not be accurately controlled the gain of reflection signal, reflection signal and aftershock signal can not correctly be distinguished, after can only shielding transmitting
A period of time, this period can not ranging, cause blind area big or blind area be apart from unstable.Also have to use on pcb board and divide
From the range-measurement system of reduction blind area built of analog device, but consistency is bad, and increased analog device cost is much higher.
Summary of the invention
In order to solve above-mentioned technical problem of the existing technology, the present invention provides a kind of ultrasonic distance measurement chip, benefits
Realize that time gain is adjusted with chip interior logic circuit control time gain module, eliminating aftershock influences, reduce range hole,
Expand measurement distance, one piece of chip adds the peripheral circuit of only a few to can be achieved with ultrasonic distance measurement function again.Used technology
Scheme is as follows:
A kind of ultrasonic distance measurement chip is internally integrated logic control circuit and is connected to the logic control circuit
Ultrasonic wave transmitting circuit, time gain module, amplitude compare decision circuit, and the logic control circuit is according to the ranging received
Trigger signal starts ultrasonic wave transmitting circuit, and time gain module to carry out dynamic increasing to the reflection signal received at any time
Benefit；The amplitude compares decision circuit and judges whether there is back by comparing the output valve and preset threshold of the time gain module
Acoustical signal, and aftershock signal can be distinguished；It is one section that the logic control circuit, which will measure distance output according to the echo signal,
Pulse width.
Specifically, the time gain module includes sequentially connected time gain control circuit, time gain adjusting electricity
Road；The amplitude compares decision circuit and presets the threshold value, when the output valve of time gain adjusting circuit is more than the threshold value,
The amplitude compares decision circuit output high level.
Specifically, the time gain control circuit is equipped with counter, after detecting ranging trigger signal, the counting
Device is resetted and is started counting, and counter results are converted into thermometer code, and the thermometer code adjusts circuit to control time gain
Amount of gain.
Specifically, it includes operational amplifier and resistance-feedback network, resistance-feedback network that the time gain, which adjusts circuit,
Resistance value pass through one group of switch control.
Specifically, the time gain adjusts the operational amplifier and resistance feedback that circuit includes two-stage or plural serial stage
The resistance value of network, resistance-feedback network passes through one group of switch control.
Specifically, the resistance value of resistance-feedback network increases with the increase of Counter Value, and time gain adjusts circuit
Amount of gain increases therewith.
Specifically, when the amplitude compares decision circuit output high level, show that the logic control circuit receives back
Acoustical signal, trigger pulse width become low level.
Specifically, the threshold value VREF=3/4VDD, wherein VVDD indicates supply voltage.
Specifically, the outside of the range finding chip is also connected to transmitting probe and receiving transducer, and transmitting probe is by described super
Sonic wave transmitting circuit driving, receiving transducer is for receiving the reflection signal.
Specifically, described to distinguish aftershock signal specifically: after ranging trigger signal just starts, the aftershock signal is through dynamic
Still less than the threshold value after state gain.
The utility model has the advantages that the present invention realizes ultrasonic distance measurement function using single-chip, the amplifier and list on circuit board are eliminated
Piece machine greatly reduces the passive devices such as the resistance capacitance on circuit board, greatly reduces device cost and welding cost；
Distance measurement function is realized using single-chip, is greatly reduced circuit board volume, be can be applied in various micromation equipment,
Single chip solution reduces power consumption, highly beneficial to low-power dissipation system；
Distance measurement function is realized using single-chip, is reduced the noise of circuit board, can be amplified remote weak reflection signals,
It is able to achieve more remote ranging.
Detailed description of the invention
The drawings described herein are used to provide a further understanding of the present application, constitutes part of this application, this Shen
Illustrative embodiments and their description please are not constituted an undue limitation on the present application for explaining the application.In the accompanying drawings:
Fig. 1 is the ES Echo sounding timing diagram of the prior art；
Fig. 2 is the ultrasonic distance measuring module of the prior art；
Fig. 3 is ultrasonic distance measurement chip external interface schematic diagram of the invention；
Fig. 4 is ultrasonic distance measurement chip internal structure schematic diagram of the invention；
Fig. 5 is ultrasonic distance measurement chip ranging timing diagram of the invention；
Fig. 6 is that time gain of the invention adjusts circuit decision circuit structural schematic diagram compared with amplitude.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Below
Description only actually at least one exemplary embodiment be it is illustrative, never as to the present invention and its application or make
Any restrictions.Based on the embodiments of the present invention, those of ordinary skill in the art are not making creative work premise
Under every other embodiment obtained, shall fall within the protection scope of the present invention.
Referring to Fig. 3, ultrasonic distance measurement chip provided in an embodiment of the present invention is externally just like lower interface, chip TP/TN pipe
Foot connects the both ends of a ultrasonic wave transmitting differential probe, and RP/RN pin connects the both ends of a reception differential probe；VDD/VSS pipe
Foot connects a pair of of 3V~5V DC power supply；XI/XO pin connects crystal oscillator；TRIG pin connects ranging trigger signal, and single-chip is again
The peripheral circuit of only a few is added to can be achieved with ultrasonic distance measurement function.
Referring to fig. 4, ultrasonic distance measurement chip provided in an embodiment of the present invention, has been internally integrated logic control circuit and company
It is connected to the ultrasonic wave transmitting circuit of the logic control circuit, time gain module, amplitude and compares decision circuit, the logic control
Circuit processed starts ultrasonic wave transmitting circuit according to the ranging trigger signal received, and time gain module is to anti-to what is received
It penetrates signal and carries out dynamic gain at any time；The amplitude compares decision circuit by comparing the output valve of the time gain module
Echo signal is judged whether there is with preset threshold, and aftershock signal can be distinguished；The logic control circuit is believed according to the echo
Number will measure distance output is one section of pulse width.
The time gain module includes sequentially connected time gain control circuit, time gain adjusting circuit.
Specifically, the time gain control circuit is equipped with counter, after detecting ranging trigger signal, the counting
Device is resetted and is started counting, and adds 1 at interval of 1 millisecond counter, counter results are converted into thermometer code, and the thermometer code is to control
Time gain processed adjusts the amount of gain of circuit.
Referring to Fig. 6, it includes operational amplifier and resistance-feedback network, resistance-feedback network that the time gain, which adjusts circuit,
Resistance value pass through one group of switch control.The resistance value of resistance-feedback network increases, time gain tune with the increase of Counter Value
The gain on economize on electricity road increases therewith.Two-stage or multistage same structures in series can provide higher adjustable range.
Specifically, time gain adjusts the resistance-feedback network of circuit when the counter of time gain control circuit is 0
In switch be all closed, at this time gain is minimum.Counter is every to increase by 1, and the number that thermometer code is 1 is increased by 1, thermometer code control
The switch of the resistance-feedback network of system opens one with regard to multibreak.As counter increases, feedback resistance resistance value also increases, time gain
The gain for adjusting circuit gradually increases at any time.In one embodiment, after 8 milliseconds, time gain adjusts the gain of circuit
Adjust maximum.In other embodiments, resistance-feedback network can connect more resistance, at the same each resistance separately through
Switch in parallel is controlled.
The amplitude compares decision circuit and presets the threshold value, when the output valve of time gain adjusting circuit is more than the threshold
When value, the amplitude compares decision circuit output high level, shows that the logic control circuit receives echo signal, triggers arteries and veins
It rushes width and becomes low level.In one embodiment, taking the threshold value is VREF=3/4VDD, and wherein VDD indicates supply voltage.
Referring to Fig. 5, after logic circuit detects the rising edge of ranging trigger signal, chip TP/TN pin sends ultrasonic wave
Transmitting probe (TN is the differential signal of TP, not drawn in the figure) is given in pulse, starts the square-wave signal for emitting 8 period 40KHz,
And start to start the counter of time gain control circuit.Receiving transducer receives reflection signal and returns to core by RP/RN pin
Piece (RN is the differential signal of RP, not drawn in the figure), chip interior detected reflectance signal.3 milli before after the trigger signal
Within second, being closer for signal is reflected at this time, reflection signal is by with the amplification of lower amplification factor, the reflection signal of short distance
Amplitude is bigger, can be amplified to the full amplitude of oscillation, and aftershock signal is amplified a half amplitude point of the multiple less than the full amplitude of oscillation, the aftershock
Signal still less than the threshold value, therefore reflects signal and aftershock signal and can correctly be distinguished after dynamic gain.5 milliseconds it
Afterwards, there is no aftershock signals, and farther out, time gain adjusts circuit and is gradually amplified to very high times the distance of reflection signal at this time
Number, the full amplitude of oscillation can be also amplified to by reflecting signal at a distance.The output valve that time gain adjusts circuit compares judgement to amplitude
Circuit is made comparisons judgement, more than the threshold value VREF that amplitude compares decision circuit setting, shows to detect echo signal, amplitude compares
Decision circuit exports high level, while triggering width-pulse and becoming low level, will measure distance by ECHO pin with one section of arteries and veins
The form output of width is rushed, pulse width is with measuring apart from direct proportionality.Distance s and pulse width t are measured described in final
Relationship is s=340t/2.
The present invention realizes distance measurement function with single-chip, has been internally integrated logic control circuit, ultrasonic signal transmitting electricity
Road, echo signal amplification and AGC circuit, compare threshold value and judge the circuit of distance, eliminate the amplifier on circuit board
And single-chip microcontroller, the passive devices such as the resistance capacitance on circuit board are greatly reduced, device cost and welding cost are greatly reduced；
Circuit board volume is greatly reduced, can be applied in various micromation equipment, single chip solution reduces power consumption, to low-power consumption system
It unites highly beneficial；The noise of circuit board is reduced, remote weak reflection signals can be amplified, be able to achieve more remote survey
Away from.
In addition, above-mentioned the embodiment of the present application serial number is for illustration only, do not represent the advantages or disadvantages of the embodiments.In the upper of the application
It states in embodiment, all emphasizes particularly on different fields to the description of each embodiment, there is no the part being described in detail in some embodiment, may refer to it
The associated description of his embodiment.
These are only the preferred embodiment of the present invention, is not intended to restrict the invention, for those skilled in the art
For member, the invention may be variously modified and varied.All within the spirits and principles of the present invention, it is made it is any modification,
Equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of ultrasonic distance measurement chip, which is characterized in that the range finding chip has been internally integrated logic control circuit and connection
Compare decision circuit, the logic control to the ultrasonic wave transmitting circuit of the logic control circuit, time gain module, amplitude
Circuit starts ultrasonic wave transmitting circuit according to the ranging trigger signal received, and time gain module is to the reflection to receiving
Signal carries out dynamic gain at any time；The amplitude compare decision circuit by comparing the time gain module output valve with
Preset threshold judges whether there is echo signal, and can distinguish aftershock signal；The logic control circuit is according to the echo signal
It is one section of pulse width that distance output, which will be measured,.
2. a kind of ultrasonic distance measurement chip according to claim 1, which is characterized in that the time gain module include according to
Time gain control circuit, the time gain of secondary connection adjust circuit；The amplitude compares decision circuit and presets the threshold value, when
When the output valve that time gain adjusts circuit is more than the threshold value, the amplitude compares decision circuit output high level.
3. a kind of ultrasonic distance measurement chip according to claim 1 or 2, which is characterized in that the time gain control electricity
Road is equipped with counter, and after detecting ranging trigger signal, the counter resets are simultaneously started counting, and counter results are converted into
Thermometer code, the thermometer code adjust the amount of gain of circuit to control time gain.
4. a kind of ultrasonic distance measurement chip according to claim 3, which is characterized in that the time gain adjusts circuit packet
Operational amplifier and resistance-feedback network are included, the resistance value of resistance-feedback network passes through one group of switch control.
5. a kind of ultrasonic distance measurement chip according to claim 3, which is characterized in that the time gain adjusts circuit packet
The operational amplifier and resistance-feedback network of two-stage or plural serial stage are included, the resistance value of resistance-feedback network passes through one group of switch control
System.
6. a kind of ultrasonic distance measurement chip according to claim 4 or 5, which is characterized in that the resistance value of resistance-feedback network
Increase with the increase of Counter Value, the amount of gain that time gain adjusts circuit increases therewith.
7. a kind of ultrasonic distance measurement chip according to claim 2, which is characterized in that it is defeated that the amplitude compares decision circuit
Out when high level, show that the logic control circuit receives echo signal, trigger pulse width becomes low level.
8. a kind of ultrasonic distance measurement chip according to claim 1 or 2, which is characterized in that the threshold value VREF=3/4
VDD, wherein VVDD indicates supply voltage.
9. a kind of ultrasonic distance measurement chip according to claim 1, which is characterized in that the outside of the range finding chip also connects
It is connected to transmitting probe and receiving transducer, transmitting probe is driven by the ultrasonic wave transmitting circuit, and receiving transducer is described for receiving
Reflect signal.
10. a kind of ultrasonic distance measurement chip according to claim 1 or 2, which is characterized in that described to distinguish aftershock signal
Specifically: after ranging trigger signal just starts, the aftershock signal is after dynamic gain still less than the threshold value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910278773.9A CN109884644A (en) | 2019-04-09 | 2019-04-09 | A kind of ultrasonic distance measurement chip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910278773.9A CN109884644A (en) | 2019-04-09 | 2019-04-09 | A kind of ultrasonic distance measurement chip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109884644A true CN109884644A (en) | 2019-06-14 |
Family
ID=66936518
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910278773.9A Pending CN109884644A (en) | 2019-04-09 | 2019-04-09 | A kind of ultrasonic distance measurement chip |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109884644A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112148105A (en) * | 2020-09-14 | 2020-12-29 | 浙江大华技术股份有限公司 | Access control system awakening method and device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2657016Y (en) * | 2003-09-05 | 2004-11-17 | 徐建俊 | Ultrasonic range finder with sensitivity automatic gain control function |
| US20150292879A1 (en) * | 2014-04-11 | 2015-10-15 | SZ DJI Technology Co., Ltd | Proximity sensing systems and methods |
| CN107765247A (en) * | 2016-08-21 | 2018-03-06 | 王东玉 | One kind is without crosstalk ranging system hardware circuit |
| CN107850666A (en) * | 2015-09-29 | 2018-03-27 | 密克罗奇普技术公司 | Ultrasonic ranging ancillary equipment based on core independence ancillary equipment |
| CN210090672U (en) * | 2019-04-09 | 2020-02-18 | 苏州顺憬志联新材料科技有限公司 | Ultrasonic ranging chip |
-
2019
- 2019-04-09 CN CN201910278773.9A patent/CN109884644A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2657016Y (en) * | 2003-09-05 | 2004-11-17 | 徐建俊 | Ultrasonic range finder with sensitivity automatic gain control function |
| US20150292879A1 (en) * | 2014-04-11 | 2015-10-15 | SZ DJI Technology Co., Ltd | Proximity sensing systems and methods |
| CN107850666A (en) * | 2015-09-29 | 2018-03-27 | 密克罗奇普技术公司 | Ultrasonic ranging ancillary equipment based on core independence ancillary equipment |
| CN107765247A (en) * | 2016-08-21 | 2018-03-06 | 王东玉 | One kind is without crosstalk ranging system hardware circuit |
| CN210090672U (en) * | 2019-04-09 | 2020-02-18 | 苏州顺憬志联新材料科技有限公司 | Ultrasonic ranging chip |
Non-Patent Citations (1)
| Title |
|---|
| 韩丰谈等: "《医学影像设备学》", 人民卫生出版社, pages: 633 - 635 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112148105A (en) * | 2020-09-14 | 2020-12-29 | 浙江大华技术股份有限公司 | Access control system awakening method and device |
| CN112148105B (en) * | 2020-09-14 | 2023-12-12 | 浙江大华技术股份有限公司 | Access control system awakening method and device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8353321B2 (en) | Method and system for short-range ultrasonic location sensing | |
| CN101173986B (en) | Ultrasonic distance measuring apparatus without blind zone | |
| JP3701968B2 (en) | Electromagnetic hidden object detector | |
| CN202330713U (en) | Guide collision avoidance device based on multiple ultrasonic sensors | |
| WO2005034717A3 (en) | Bladder measurement | |
| US4953141A (en) | Sonic distance-measuring device | |
| CN207473089U (en) | Object detector | |
| CA2520065A1 (en) | Obstacle detection apparatus | |
| CN209264954U (en) | Ultrasonic distance measurement obstacle avoidance system | |
| CN102621552A (en) | High-precision ultrasonic range-measuring system | |
| CN108279416A (en) | A kind of ultrasonic ranging system and its accurate method for measuring echo arrival time | |
| CN109884644A (en) | A kind of ultrasonic distance measurement chip | |
| CN201654232U (en) | Intelligent ultrasonic distance measuring sensor | |
| CN103616691A (en) | Ultrasonic ranging device | |
| CN109387842A (en) | Ultrasonic distance measurement obstacle avoidance system | |
| CN2784945Y (en) | Ultrasonic distance-measuring sensor | |
| CN210090672U (en) | Ultrasonic ranging chip | |
| CN201814797U (en) | Blind guidance device | |
| CN106872984A (en) | Using the depth-logger detecting system of wave amplitude method | |
| US3548370A (en) | Depth sounder | |
| CN1103714A (en) | Method for decreasing blind zone of ultrasonic wave range finder | |
| CN112147620A (en) | System and method for measuring ultrasonic flight time in pipeline | |
| Wobschall et al. | An ultrasonic/optical pulse sensor for precise distance measurements | |
| CN206209105U (en) | A kind of high-precision ultrasonic ranging device | |
| JPS6264973A (en) | Ultrasonic range finder |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |