外文文獻及翻譯---超聲波測距儀

1、<p><b>　　原文：</b></p><p>　　Ultrasonic distance meter</p><p>　　Document Type and Number:United States Patent 5442592 </p><p>　　Abstract:An ultrasonic distance meter c

2、ancels out the effects of temperature and humidity variations by including a measuring unit and a </p><p>　　reference unit. In each of the units, a repetitive series of pulses is </p><p>　　gener

3、ated, each having a repetition rate directly related to the </p><p>　　respective distance between an electroacoustic transmitter and an </p><p>　　electroacoustic receiver. The pulse trains are p

4、rovided to respective </p><p>　　counters, and the ratio of the counter outputs is utilized to determine </p><p>　　the distance being measured. </p><p>　　Publication Date:08/15/1995

5、</p><p>　　Primary Examiner:Lobo, Ian J. </p><p>　　BACKGROUND OF THE INVENTION </p><p>　　This invention relates to apparatus for the measurement of distance </p><p>　　an

6、d, more particularly, to such apparatus which transmits ultrasonic </p><p>　　waves between two points. </p><p>　　Precision machine tools must be calibrated. In the past, this has been </p>

7、<p>　　accomplished utilizing mechanical devices such as calipers, </p><p>　　micrometers, and the like. However, the use of such devices does not </p><p>　　readily lend itself to automatio

8、n techniques. It is known that the </p><p>　　distance between two points can be determined by measuring the </p><p>　　propagation time of a wave travelling between those two points. One </p&g

9、t;<p>　　such type of wave is an ultrasonic, or acoustic, wave. When an </p><p>　　ultrasonic wave travels between two points, the distance between the </p><p>　　two points can be measured

10、by multiplying the transit time of the wave </p><p>　　by the wave velocity in the medium separating the two points. It is </p><p>　　therefore an object of the present invention to provide appara

11、tus </p><p>　　utilizing ultrasonic waves to accurately measure the distance between </p><p>　　two points. </p><p>　　When the medium between the two points whose spacing is being mea

12、sured </p><p>　　is air, the sound velocity is dependent upon the temperature and </p><p>　　humidity of the air. It is therefore a further object of the,present </p><p>　　invention t

13、o provide apparatus of the type described which is </p><p>　　independent of temperature and humidity variations. </p><p>　　SUMMARY OF THE INVENTION </p><p>　　The foregoing and addit

14、ional objects are attained in accordance with </p><p>　　the principles of this invention by providing distance measuring </p><p>　　apparatus which includes a reference unit and a measuring unit.

15、 The </p><p>　　reference and measuring units are the same and each includes an </p><p>　　electroacoustic transmitter and an electroacoustic receiver. The </p><p>　　spacing between t

16、he transmitter and the receiver of the reference unit </p><p>　　is a fixed reference distance, whereas the spacing between the </p><p>　　transmitter and receiver of the measuring unit is the dis

17、tance to be </p><p>　　measured. In each of the units, the transmitter and receiver are </p><p>　　coupled by a feedback loop which causes the transmitter to generate an </p><p>　　aco

18、ustic pulse which is received by the receiver and converted into an </p><p>　　electrical pulse which is then fed back to the transmitter, so that a </p><p>　　repetitive series of pulses results.

19、 The repetition rate of the pulses </p><p>　　is inversely related to the distance between the transmitter and the </p><p>　　receiver. In each of the units, the pulses are provided to a counter.

20、</p><p>　　Since the reference distance is known, the ratio of the counter outputs </p><p>　　is utilized to determine the desired distance to be measured. Since </p><p>　　both counts

21、 are identically influenced by temperature and humidity </p><p>　　variations, by taking the ratio of the counts, the resultant </p><p>　　measurement becomes insensitive to such variations. </

22、p><p>　　BRIEF DESCRIPTION OF THE DRAWINGS </p><p>　　The foregoing will be more readily apparent upon reading the following </p><p>　　description in conjunction with the drawing in whic

23、h the single FIGURE </p><p>　　schematically depicts apparatus constructed in accordance with the </p><p>　　principles of this invention. </p><p>　　DETAILED DESCRIPTION </p>&

24、lt;p>　　Referring now to the drawing, there is shown a measuring unit 10 and a </p><p>　　reference unit 12, both coupled to a utilization means 14. The </p><p>　　measuring unit 10 includes an

25、electroacoustic transmitter 16 and an </p><p>　　electroacoustic receiver 18. The transmitter 16 includes piezoelectric </p><p>　　material 20 sandwiched between a pair of electrodes 22 and 24. &l

26、t;/p><p>　　Likewise, the receiver 18 includes piezoelectric material 26 sandwiched </p><p>　　between a pair of electrodes 28 and 30. As is known, by applying an </p><p>　　electric fiel

27、d across the electrodes 22 and 24, stress is induced in </p><p>　　the piezoelectric material 20. If the field varies, such as by the </p><p>　　application of an electrical pulse, an acoustic wav

28、e 32 is generated. </p><p>　　As is further known, when an acoustic wave impinges upon the receiver </p><p>　　18, this induces stress in the piezoelectric material 26 which causes </p><

29、;p>　　an electrical signal to be generated across the electrodes 28 and 30. </p><p>　　Although piezoelectric transducers have been illustrated, other </p><p>　　electroacoustic devices may be u

30、tilized, such as, for example, </p><p>　　electrostatic, electret or electromagnetic types. </p><p>　　As shown, the electrodes 28 and 30 of the receiver 18 are coupled to </p><p>　　t

31、he input of an amplifier 34, whose output is coupled to the input of a </p><p>　　detector 36. The detector 36 is arranged to provide a signal to the </p><p>　　pulse former 38 when the output fro

32、m the amplifier 34 exceeds a </p><p>　　predetermined level. The pulse former 38 then generates a trigger pulse </p><p>　　which is provided to the pulse generator 40. In order to enhance the <

33、/p><p>　　sensitivity of the system, the transducers 16 and 18 are resonantly </p><p>　　excited. There is accordingly provided a continuous wave oscillator 42 </p><p>　　which provides a

34、 continuous oscillating signal at a fixed frequency, </p><p>　　preferably the resonant frequency of the transducers 16 and 18. This </p><p>　　oscillating signal is provided to the modulator 44.

35、To effectively </p><p>　　excite the transmitter 16, it is preferable to provide several cycles </p><p>　　of the resonant frequency signal, rather than a single pulse or single </p><p&

36、gt;　　cycle. Accordingly, the pulse generator 40 is arranged, in response to </p><p>　　the application thereto of a trigger pulse, to provide a control pulse </p><p>　　to the modulator 44 having

37、a time duration equal the time duration of a </p><p>　　predetermined number of cycles of the oscillating signal from the </p><p>　　oscillator 42. This control pulse causes the modulator 44 to pa

38、ss a </p><p>　　"burst" of cycles to excite the transmitter 16. </p><p>　　When electric power is applied to the described circuitry, there is </p><p>　　sufficient noise at

39、the input to the amplifier 34 that its output </p><p>　　triggers the pulse generator 40 to cause a burst of oscillating cycles </p><p>　　to be provided across the electrodes 22 and 24 of the tra

40、nsmitter 16. </p><p>　　The transmitter 16 accordingly generates an acoustic wave 32 which </p><p>　　impinges upon the receiver 18. The receiver 18 then generates an </p><p>　　electr

41、ical pulse which is applied to the input of the amplifier 34, </p><p>　　which again causes triggering of the pulse generator 40. This cycle </p><p>　　repeats itself so that a repetitive series o

42、f trigger pulses results at </p><p>　　the output of the pulse former 38. This pulse train is applied to the </p><p>　　counter 46, as well as to the pulse generator 40. </p><p>　　The

43、 transmitter 16 and the receiver 18 are spaced apart by the distance </p><p>　　"D" which it is desired to measure. The propagation time "t" for an </p><p>　　acoustic wave 32

44、travelling between the transmitter 16 and the receiver </p><p>　　18 is given by: t=D/V s </p><p>　　where V s is the velocity of sound in the air between the transmitter </p><p>　　16

45、 and the receiver 18. The counter 46 measures the repetition rate of </p><p>　　the trigger pulses, which is equal to 1/t. Therefore, the repetition </p><p>　　rate is equal to V s /D. The velocit

46、y of sound in air is a function of </p><p>　　the temperature and humidity of the air, as follows: ##EQU1## where T </p><p>　　is the temperature, p is the partial pressure of the water vapor, H i

47、s </p><p>　　the barometric pressure, Γ w and Γ a are the ratio of constant </p><p>　　pressure specific heat to constant volume specific heat for water vapor </p><p>　　and dry air, r

48、espectively. Thus, although the repetition rate of the </p><p>　　trigger pulses is measured very accurately by the counter 46, the sound </p><p>　　velocity is influenced by temperature and humid

49、ity so that the measured </p><p>　　distance D cannot be determined accurately. </p><p>　　In accordance with the principles of this invention, a reference unit </p><p>　　12 is provid

50、ed. The reference unit 12 is of the same construction as </p><p>　　the measuring unit 10 and therefore includes an electroacoustic </p><p>　　transmitter 50 which includes piezoelectric material

51、52 sandwiched </p><p>　　between a pair of electrodes 54 and 56, and an electroacoustic receiver </p><p>　　58 which includes piezoelectric material 60 sandwiched between a pair </p><p&

52、gt;　　of electrodes 62 and 64. Again, transducers other than the </p><p>　　piezoelectric type can be utilized. The transmitter 50 and the receiver </p><p>　　58 are spaced apart a known and fixed

53、reference distance "D R ". The </p><p>　　electrodes 62 and 64 are coupled to the input of the amplifier 66, </p><p>　　whose output is coupled to the input of the detector 68. The outpu

54、t of </p><p>　　the detector 68 is coupled to the pulse former 70 which generates </p><p>　　trigger pulses. The trigger pulses are applied to the pulse generator </p><p>　　72 which c

55、ontrols the modulator 74 to pass bursts from the continuous </p><p>　　wave oscillator 76 to the transmitter 50. The trigger pulses from the </p><p>　　pulse former 70 are also applied to the coun

56、ter 78. </p><p>　　Preferably, all of the transducers 16, 18, 50 and 58 have the same </p><p>　　resonant frequency. Therefore, the oscillators 42 and 76 both operate </p><p>　　at tha

57、t frequency and the pulse generators 40 and 72 provide equal </p><p>　　width output pulses. </p><p>　　In usage, the measuring unit 10 and the reference unit 12 are in close </p><p>

58、　　proximity so that the sound velocity in both of the units is the same. </p><p>　　Although the repetition rates of the pulses in the measuring unit 10 </p><p>　　and the reference unit 12 are ea

59、ch temperature and humidity dependent, </p><p>　　it can be shown that the distance D to be measured is related to the </p><p>　　reference distance D R as follows: i D=D R (1/t R )/(1/t) </p&g

60、t;<p>　　where t R is the propagation time over the distance D R in the </p><p>　　reference unit 12. This relationship is independent of both temperature </p><p>　　and humidity. </p>

61、<p>　　Thus, the outputs of the counters 46 and 78 are provided as inputs to </p><p>　　the microprocessor 90 in the utilization means 14. The microprocessor </p><p>　　90 is appropriately p

62、rogrammed to provide an output which is </p><p>　　proportional to the ratio of the outputs of the counters 46 and 78, </p><p>　　which in turn are proportional to the repetition rates of the <

63、/p><p>　　respective trigger pulse trains of the measuring unit 10 and the </p><p>　　reference unit 12. As described, this ratio is independent of </p><p>　　temperature and humidity and

64、, since the reference distance D R is </p><p>　　known, provides an accurate representation of the distance D. The </p><p>　　utilization means 14 further includes a display 92 which is coupled to

65、 </p><p>　　and controlled by the microprocessor 90 so that an operator can readily </p><p>　　determine the distance D. </p><p>　　Experiments have shown that when the distance betwee

66、n the transmitting </p><p>　　and receiving transducers is too small, reflections of the acoustic </p><p>　　wave at the transducer surfaces has a not insignificant effect which </p><p&

67、gt;　　degrades the measurement accuracy. Accordingly, it is preferred that </p><p>　　each transducer pair be separated by at least a certain minimum </p><p>　　distance, preferably about four inch

68、es.</p><p><b>　　譯文：</b></p><p><b>　　超聲波測距儀</b></p><p>　　文件類型和數(shù)目：美國專利5442592 </p><p>　　摘要：提出了一種超聲波測距儀來抵消溫度和濕度的變化，包括測量單元和參考</p><p>　　

69、標準。在每一個單位，重復的產生一系列脈沖，每一個重復直接關系到發(fā)射機和</p><p>　　接收機之間的距離。脈沖串提供給各自的計數(shù)器，然后利用計數(shù)器所測得的數(shù)據(jù)</p><p><b>　　進行距離的測量。</b></p><p>　　出版日期： 1995年8月15日 </p><p>　　主審查員：羅保.伊恩j. &

70、lt;/p><p><b>　　一、背景發(fā)明 </b></p><p>　　本發(fā)明涉及到儀器的測量距離，更特別是，這種儀器傳送超聲波于兩點之間。精密機器必須校準。在過去，這已經可以利用卡鉗，微米等工具來校準機械設備。不過，使用這種工具并不容易實現(xiàn)自動化。據(jù)了解，該兩點之間距離可以通過測量波在兩點之間傳播時間來確定。這樣一個類型的波可以是一種超聲波，或聲，或波。當超聲波傳播

71、與兩點之間時，兩個點之間的距離可以通過由超聲波波速乘以他的傳播時間，在合適的分離的兩點。因此，這是一個發(fā)明提供儀器利用超聲波準確測量兩點之間距離的方法。 </p><p>　　當中等兩個點之間的介質是空氣，聲速是取決于溫度和空氣相對濕度。因此，這</p><p>　　個發(fā)明的進一步目標是，目前的發(fā)明提供儀器的方法如同所描述的一樣是獨立于溫度和濕度的變化的。</p><p

72、><b>　　二、綜述發(fā)明 </b></p><p>　　前述的和額外的目標已經實現(xiàn)了根據(jù)這些原則的這項發(fā)明提供距離測量儀器，其中包括一個參考的單元和測量單元。參考和測量單元是相同的，每個單元都包括一個電聲波的發(fā)射機和接收機。參考單元的發(fā)射器和接收器之間的間隔是一個固定的參考距離，然而測量單元的發(fā)射器和接收器之間的距離才是我們所要測量的部分。在每一個單元中，發(fā)射機和接收機都連接了一個反

73、饋環(huán)路，以使發(fā)射機產生由接收器接收的聲波生脈沖，然后由接收器轉換成一個電脈沖反饋到發(fā)射機，使產生一系列重復脈沖的結果。脈沖重復率是成反比關系發(fā)射器和接收器之間的距離。在每一個單元，脈沖被用來提供給一個計數(shù)器。由于參考的距離是已經知道了的，所以計數(shù)器所輸出的數(shù)據(jù)被用來確定所期望測得的距離。由于溫度和適度的變化，這兩方面都會造成相同的影響，利用計數(shù)器所提供的數(shù)據(jù)，這樣的測量對于溫度和濕度引起的變化一樣是沒有辦法避免的。</p>

74、<p><b>　　三、簡要說明圖紙 </b></p><p>　　通過讀接下來的說明前面的敘述將變得更加明顯，這個關于電路原理圖的描述在</p><p>　　于這項發(fā)明相關規(guī)律保持了相當?shù)囊恢滦浴?lt;/p><p><b>　　四、詳細說明 </b></p><p>　　根據(jù)現(xiàn)在的繪圖，

75、有結果表明，測量單位和10參考單位12，都聯(lián)結起來組成可以利用的單元14 。測量單位包括10包括了一個電信號發(fā)射機16和一個電信號接收機18 。發(fā)射器16包括了夾著一對電極22河24的壓電材料20。同樣,接收機18，包括了夾著一對電極28河30的壓電材料26。眾所周知，通過利用電極22和24之間產生的電場，壓電材料20將產生壓力。如果該電場產生變化，例如通過一個電脈沖，就會產生一個聲波32。因此，進一步得知，當聲波影響到接收器18的時候

76、，這時會引起接收器上的壓電材料26產生機械變形，同時產生一個電信號通過28和30這一對電極。雖然已經對壓電傳感器作了說明，但是其他電聲裝置也可利用，例如，靜電，駐極體或電磁類型。 </p><p>　　如表所示，接收器的電極28和30將于放大器34的輸入端相連接，同時，放大器的輸出端于探測器36相連接。脈沖發(fā)生器38然后產生一個觸發(fā)脈沖，這是提供給脈沖發(fā)生器40.在為了提供靈敏度該系統(tǒng)的傳感器16和18在通常情況

77、下都是保持運作的。根據(jù)相關的需要，本發(fā)明提供了一個連續(xù)波振蕩器42，他能持續(xù)的產生一個固定頻率和連續(xù)振蕩信號，最好是同傳感器16和18能接受到的固定頻率一樣。這個振蕩信號被用來提供給調制器44。為了使發(fā)射機16右線的工作，最好的做法是提供幾個周期的共振頻率信號，而不是一個單脈沖或單周期。因此，在這里使用了脈沖發(fā)生器40，用于回應每一個觸發(fā)脈沖，提供一個控制脈沖給調制器44，讓他有一個與來自于振蕩器42的周期振蕩信號預定的相同時間。這樣的

78、控制脈沖能使調制器44傳送一個周期的突破口以觸發(fā)發(fā)射機16。 當電源被用于描述的電路，有相當大的噪音輸入到放大器34 ，以至于其輸出觸發(fā)脈沖發(fā)生器40引起了正當周期變化，這個振蕩周期是用來提供給發(fā)射器16的電極22和24。發(fā)射器16因此產生聲波32并作用于接收器18，接收器18然后產生一個電脈沖輸入放大器34，這再次觸發(fā)脈沖發(fā)生器40。這個周期</p><p>　　根據(jù)這項發(fā)明的基本原理，需要利用參考單元12。參

79、考單元12同參考單元10基本上是一樣的，其中，包括一電發(fā)射機50，以及在壓電材料52之間的一對電極54和56。接收器58，其中包括壓電材料60之間的一對電極62和64。再次，傳感器出了其他類型壓電也可以被利用。發(fā)射器50和接收器58之間的距離都是已知且固定的，設為DR。電極62和64連接到放大器66的輸入端，其輸出連接到探測器68。探測器68的輸出端連接到脈沖發(fā)生器70，脈沖發(fā)生器70產生觸發(fā)脈沖。觸發(fā)脈沖應用到脈沖發(fā)生器72以控制調制

80、器74通過連續(xù)振蕩器76傳送一段脈沖串傳遞至發(fā)射機50。來自于脈沖發(fā)生器70的觸發(fā)脈沖也用于計數(shù)器78。</p><p>　　最好是所有的傳感器16,18,50和58具有相同的共振頻率。因此，振蕩器42和76都工作在相同的頻率上，脈沖發(fā)生器40和72產生相同帶寬的輸出脈波。</p><p>　　按照慣例，測量單元10和參考單元12空間上很接近，使該聲速在這兩個單位上是相同的。雖然測量單元1

81、0和參考單元12的脈沖重復率各自依賴于各自的溫度和濕度，能證明的距離D來衡量?？梢缘贸鰷y量單元和參考單元的聯(lián)系如下iD=DR（1/tR）/（1/t）。tR是指參考單元聲波傳播與固定空間的時間。這個關系與空氣的溫度和濕度都是無關的。因此，計數(shù)器46和78的輸出被用來提供微處理器90，作為方法14。微處理器90可通過編寫程序來提供輸出。這個輸出與計數(shù)器46和78的輸出是成比例的，反過來也同測量單元10和參考單元12各自的觸發(fā)脈沖串成比例。如

82、所敘述的一樣，這些比例是不依賴于溫度和濕度的，因為參考距離DR是已知的，提供了一個準確的D的參考。這個利用方法12更進一步的包括了被微處理器控制的顯示器92，所以設備可以確定距離D。</p><p>　　試驗還表明當發(fā)射機和接收器傳感器之間的距離太小的時候，聲波的反射在傳感器表面的效果不是很明顯，以至于極大的影響了測量的精度。根據(jù)這種情況，使傳感器分開有一個相當?shù)淖钚【嚯x，最合適是4英寸。</p>