CN2645032Y

CN2645032Y - Capacitance grating measuring apparatus utilizing phase interpolation and digital circuit

Info

Publication number: CN2645032Y
Application number: CN 03276729
Authority: CN
Inventors: 吴子铭; 卢国纲
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-08-26
Filing date: 2003-08-26
Publication date: 2004-09-29
Anticipated expiration: 2013-08-26

Abstract

The utility model relates to a capacitive measuring device using phase interpolation and digitizing circuit, belonging to testing technology and instrument specialty and mechantronics technology field. The utility model provides a displacement measuring system, which is commonly used in digital caliper, digital micrometer and other measuring devices and also in digital display and numerical control of measuring instruments and machine tools, comprising a clock, a frequency-dividing driver, a sensor, a preamplifier, a frequency selective amplifier, a shaping synchronizer, a phase modulation divider, a phase detector, and an interpolation control circuit. The utility model as a real-time digital measuring system can implement high frequency multiplication to the grid pitch of capacitive sensor and gain micron and submicron measuring resolution at higher measuring speed, which enables the capacitive sensor to be used in automatic control system conveniently.

Description

Adopt the appearance grid measurement mechanism of phase run and digitizer

Technical field

The utility model is a kind of displacement measurement system, belongs to metrological testing technology and instrument specialty, electromechanical integration technology area.This measuring system is used for measurer video card chi, digital display dial gauge in full, the also digital display of the amount of being used for instrument and lathe, digital control system.The utility model is that capacitor grid transducer is used for real-time automatic control system, has also improved the measuring speed of system when improving Measurement Resolution.The utility model can make and hold the measurement resolution that the grid measuring system obtains micron order and submicron order.

Technical background

Last century, the early seventies capacitance displacement sensor was moving grid and the fixed grid structure after inductosyn and grating sensor, and it is measuring period with pitch, realized the increment type measurement, equally also use average effect and differential technique, successfully solved the displacement measurement of silk level and microstage wide range.The capacitance measurement system of being invented and obtained patent in 1972 by Swiss H.U.Meyer is called the SYLVAC system.The N.I.Andermo of Swede applied for " capacitive displacement measurement mechanism " Swedish patent on Dec 9th, 1977, and the patent No. is SE7714010, and had applied for that on Dec 12nd, 1986 U.S. Pat applied for Chinese patent CN87102624A in 4743902,1987 years.H.U.Meyer has applied for " capacitance measurement method of length and angle " Swiss Patent by name on Dec 21st, 1980, and the patent No. is CH8609/80, and has applied for the CN86107942A Chinese patent again on Dec 20th, 1981.Existing domestic used appearance grid measured chip is the SN6602 that the E78118A, the SH7122 that are produced by 101 of the Ministry of Aerospace Industry, weapons portion 214 and Shanghai Xin Mao semiconductor company produce, and its circuit is similar with the patent of Meyer, Andermo with disposal route.Conclude and get up to have following characteristics:

The first, sensor

Slide rule also can be described as read head, also claims emitter m along the moving direction some groups of transmitting electrodes that distribute, and has a receiving pole at least.Scale is that pitch is the scaleplate of constant.

The second, the feature of drive signal

Produce m road square wave power supply signal, the amplitude of each road signal is identical with frequency, and differs the 360/m degree successively.The pulse width of power supply signal is modulated square wave.

The 3rd, Signal Processing

Received signal is modulated carrier signal, through amplifying the envelope that demodulation obtains carrier signal, promptly reflects the phase-modulated signal of displacement again.Become square wave after the shaping, after the A/D conversion, obtain displacement data.

The output of above-mentioned appearance grid displacement measurement system is timesharing, and output data lags behind displacement, can not be used for real-time control system; Frequency after the displacement signal demodulation of the grid of reflection appearance on the other hand only is 1/20 of drive signal (carrier signal) frequency, has reduced the measuring speed of system; Thirdly be perfect not enough to the subdivide technology that holds grid pitch, the segmentation number is not high, and promptly Measurement Resolution is not high.

The utility model content

The purpose of this utility model:

The first, realize holding the output of grid measuring system real-time digital, make capacitor grid transducer can be used for automatic control system;

The second, realize improving the resolution of holding the grid measuring system to holding the high power segmentation of grid pitch, make resolution reach micron order and submicron order;

The 3rd, do not adopt modulation and countermodulation technology in this measuring system, and improve the speed of holding the grid measuring system with the way that improves the phase-modulation wave frequency.

Technical essential of the present utility model is as shown in Figure 1: adopt real-time digital display circuit, amplitude, the frequency of sensor actuation signal are identical, and phase place is to differ 45 ° eight road square waves successively, and frequency of rectangular wave is clock f ₀The n frequency division, the displacement signal that receiving pole obtains is the phase-modulation wave identical with driving signal frequency, the phase modulation wave frequency also is that clock is transferred f ₀The n frequency division, n is the segmentation number that holds grid pitch τ, can select arbitrarily, the one-period of phase-modulated signal is a pitch holding grid, with the phase interpolation method pitch is carried out the interpolation segmentation, τ/n is the minimum step pitch of measuring system, obtains real-time dfisplacement pulse from interpolation control circuit output terminal OUT1 and OUT2, pulse equivalency is the minimum step pitch of displacement, and the frequency of output pulse is the speed of sensor displacement.Its rigid structure is: clock f ₀Be connected with frequency division driver, phase modulation frequency divider, interpolation control circuit, shaping synchronizer respectively, the frequency division driver is connected with sensor, sensor is connected to phase detector with prime amplifier, frequency-selecting amplifier, shaping synchronizer after connecting, the phase modulation frequency divider is connected with phase detector, interpolation control circuit respectively, and interpolation control circuit has two output terminal OUT ₁, OUT ₂, OUT ₁Output terminal links to each other with the phase modulation frequency divider; Output signal end OUT ₁And OUT ₂Output adds/subtracts count pulse CP+/CP-, OUT respectively ₁And OUT ₂Be connected to respectively numerical control CNC system also can, be connected to parallel again decoder driver, the LCD display of inserting behind the up-down counter.

The utility model will hold the grid measuring system and change into real-time measuring system by the measuring system of timesharing, and carry out the high power segmentation to holding grid pitch, thereby improve the resolution of measuring system.Owing to adopt the phase modulating system of upper frequency, also improve measuring speed, the output signal of this circuit is that two-way adds CP+, subtracts the CP-pulse signal, each pulse is the minimum step pitch of measuring system, again by up-down counter 10 count measurement displacements, or send into FEEDBACK CONTROL CNC system 13 and realize control in real time.Technical essential of the present utility model as shown in Figure 1, the f of clock 1 ₀Realize the n frequency divisions through frequency division driver 2, and to export eight tunnel frequencies be f ₀The square wave of/n removes driving sensor 3.Obtaining frequency on sensor 3 receiving pole R still is f ₀The phase-modulation wave of/n, phase place are that 2 π x/ τ (wherein τ is a pitch, and x is the displacement of sensor) become with measuring distance x.Phase converter 7 carries out n frequency division output reference and dashes than the traveling wave maser of phase pulse and sensor 3 outputs and enter phase demodulation in the phase detector 8 through prime amplifier 4, frequency-selecting amplifier 5, shaping synchronizer 6, again behind interpolation control circuit 9, at output terminal OUT ₁And OUT ₂Can obtain to represent the count pulse CP+ and the CP-of positive negative direction.The phase modulation frequency divider is connected with frequency division driver 2, shaping synchronizer 6 respectively.Wherein n can set arbitrarily for holding the segmentation number of grid pitch τ, as 500,1000 ..., 5000 etc., the equivalent of count pulse CP can be 10 μ m, 5 μ m, 1 μ m, 0.5 μ m, 0.1 μ m, the displacement x of count pulse CP and sensor is in real time synchronous.CP can send into up-down counter 10, shows displacement through decoding/driver 11 in LCD display 12, Here it is digital display.Also can directly send in the numerical control CNC system 13.The utility model and existing appearance grid measuring system difference: first point, output pulse signal is real-time, can be used for numerical control; Second point can carry out the measurement of any high power n segmentation realization submicron order to holding grid pitch; Thirdly, the driving signal frequency of sensor is consistent with the frequency of received signal, promptly is both f ₀/ n, rather than prevailing system 1/20.

Description of drawings

The utility model specifically describes and embodiment is narrated by following diagram.

Fig. 1. appearance grid measuring system block diagram of the present utility model;

Among the figure: 1-clock, 2-frequency division driver, 3-sensor, 4-prime amplifier, 5-frequency-selecting amplifier, 6-shaping synchronizer, 7-phase converter, 8-phase detector, 9-interpolation control circuit, 10-up-down counter, 11-decoder driver, 12-display, 13-CNC system

Fig. 2. hold the synoptic diagram of grid read heads (slide rule) and scale;

Among the figure: 2-frequency division driver, 3-sensor, 4-prime amplifier

Fig. 3. the driving circuit of sensor and receiving circuit;

Among the figure: 1-clock, 2-frequency division driver, 3-sensor, 4-prime amplifier, 5-frequency-selecting amplifier;

Fig. 4. phase modulation frequency dividing circuit, shaping synchronousing circuit, phase discriminator, interpolation control circuit;

Among the figure: 1-clock, 6-shaping synchronously, 7-phase converter, 8-phase detector, 9-interpolation control circuit.

Embodiment

The utility model is applicable to and holds the grid general purpose transducer, the sensor construction synoptic diagram as shown in Figure 2, E is an emitter, M is a repeller, S is a screening electrode, R is a receiving pole, τ is a pitch of holding grid, M and S are on scale, E and R are on slide rule.Driving circuit of the present utility model is eight road square waves 2, and the amplitude of each road power supply signal is identical with frequency, and phase place differs 45 ° successively.Frequency of rectangular wave is f ₀/ n, f ₀Be the frequency of clock 1, n is a pitch segmentation number, can set arbitrarily.Its circuit connects as follows: sensor passes through capacitor C ₁With preamplifier IC ₁Anode connects, IC ₁Forward end connects resistance R simultaneously ₃, R ₃Connect resistance R respectively ₁And R ₂, R ₁Connect power supply, R ₂Ground connection; IC ₁Negative end connect resistance R respectively ₄, R ₅, R ₅Respectively with IC ₁Output terminal and capacitor C ₂Connect resistance R ₄Other end ground connection; Capacitor C ₂The other end connect capacitor C respectively ₃And resistance R ₆, R ₆Other end ground connection, C ₃The other end connect capacitor C respectively ₄, C ₅And resistance R ₇, R ₇Other end ground connection, C ₄Other end selecting audio amplifier IC respectively ₂Negative end and resistance R ₈, R ₈The other end meet IC respectively ₂Output terminal and C ₅, IC ₂Forward end ground connection.What the driving circuit of sensor and receiving circuit produced eight tunnel drive signals as shown in Figure 3 is frequency division driver 2.Clock f ₀Behind the 4/n frequency division, insert trigger IC ₄Input end of clock, IC ₄Q termination D end meet trigger IC again ₆Input end of clock, IC ₄Q termination trigger IC ₅Input end of clock, IC ₅Q termination IC ₆D end, meet trigger IC again ₇Input end of clock, IC ₅Q termination trigger IC ₈Input end of clock, IC ₆Q termination trigger IC ₉Input end of clock, IC ₆Q termination IC ₅D end meet trigger IC again ₁₀Input end of clock, IC ₇Q termination IC ₈D end, IC ₈Q termination IC ₇D end, IC ₉Q termination IC ₁₀D end, IC ₁₀Q termination IC ₉D end; IC ₇, IC ₈, IC9, IC ₁₀Q and Q end insert sensors as eight tunnel outputs.The output signal of sensor 3 is staircase waveforms, and frequency still is f ₀/ n, phase place be 2 π x/ τ wherein x be displacement, behind prime amplifier 4 and frequency-selecting amplifier 5, obtain the sine wave signal sin[27 π (f of phase modulation ₀/ n) t ± 2 π x/ τ], t is the time.Amplifier IC among Fig. 3 ₁Positive termination capacitor C ₁And resistance R ₃, R ₃The other end by R ₁And R ₂Power amplifier IC among Fig. 3 after the dividing potential drop ₂Negative terminal connect capacitor C ₄, resistance R ₈, R ₈Another termination IC ₂Output terminal.Capacitor C in the frequency-selecting amplifier 5 ₃, C ₄, C ₅And resistance R ₇Meet some C altogether ₄And R ₈A termination IC ₂Negative terminal, R ₈And C ₅Another termination IC ₂Output, R ₇Other end ground connection, C ₃Another termination C ₂Output.Shaping and synchronizing circuit are shown in 6 among Fig. 4, and the phase-modulated signal J1 that represents displacement is through C ₆Input to amplifier IC ₃Negative terminal, resistance R ₉One termination IC ₃Another termination of negative terminal V _Cc/ 2, IC ₃Positive terminating resistor R ₁₀And R ₁₁, R ₁₀Another termination V _Cc/ 2, R ₁₁Another termination IC ₃Output terminal is again through resistance R ₁₂Meet Vcc, IC ₃Output terminal is held through Sheffer stroke gate IC through the D of ICC ₁₆What obtain the row ripple after the shaping synchronously is transferred to phase detector 8 again than phase pulse.Phase converter 7 is made up of frequency divider, d type flip flop and control gate, output reference than phase pulse and traveling-wave ratio mutually pulse carry out phase demodulation, the signal that makes the output signal of phase detector 8 follow capable ripple all the time changes.The phase detector of being made up of Sheffer stroke gate 8 detects the pulse of traveling-wave ratio phase and benchmark than the phase relation of pulse mutually.Phase detector 8, phase converter 7 and time clock 15.Be transferred to the interpolation control circuit 9 that Sheffer stroke gate is formed, just can be at output terminal OUT ₁And OUT ₂Obtain representing the count pulse CP+ and the CP-of both forward and reverse directions displacement.Concrete circuit connects as follows: the phase-modulated signal of Displacement Measurement passes through capacitor C ₆Be connected to amplifier IC ₃Negative end, resistance R ₉Also be connected to IC ₃Negative end, R ₉Other end connecting resistance R ₁₀Connect power Vcc/2 again, R ₁₀Another termination IC ₃Forward end, resistance R ₁₁Meet IC ₃Forward end, R ₁₁Another termination IC ₃Output terminal, resistance R ₁₂Meet IC ₃Output terminal, R ₁₂Another termination power; IC ₃Output terminal meet trigger IC ₁₁D end, IC ₁₁Q termination IC ₁₂D end, be connected to Sheffer stroke gate IC again ₁₆Input end, trigger IC ₁₂Q end also be connected to trigger IC ₁₆Another input end, IC ₁₁And IC ₁₂Input end of clock meet clock f respectively ₀The input circuit connection of phase modulation frequency divider 7 is as follows: output terminal OUT ₁Be connected to trigger IC ₁₃Input end of clock, trigger IC ₁₃Q termination D end, OUT ₁Termination Sheffer stroke gate IC ₁₇Input end, IC ₁₃Q termination IC ₁₇Another input end, IC ₁₇Output termination Sheffer stroke gate IC ₁₈Input, Sheffer stroke gate IC ₂₆Output termination Sheffer stroke gate IC ₁₈Another input end, IC ₁₈Output signal be connected to trigger IC through 4/n frequency division rear end ₁₄Input end of clock, IC ₁₄Q termination D end, trigger IC ₁₅Input end of clock meet clock f ₀, Sheffer stroke gate IC ₁₉Input termination IC ₁₅Q end, IC ₁₉Another input termination IC ₁₅D end meet IC again ₁₄Q end, IC ₁₉Output terminal and IC ₁₆Output terminal insert respectively by Sheffer stroke gate IC ₂₀And IC ₂₁Two input ends of the comparer of forming 8; Sheffer stroke gate IC ₂₂, IC ₂₃, IC ₂₄, IC ₂₅Form interpolation control circuit, IC ₂₄Output terminal output positive-displacement pulse CP+, IC ₂₅Output terminal output negative sense dfisplacement pulse CP-.

The utility model advantage and effect: the utility model is a kind of appearance grid measuring system that adopts phase run and digitizer, as displacement measurement.Be usually used in digital display appliance such as slide calliper rule and clock gauge, also the digital display of the amount of being used for instrument and lathe, digital control system.Existing appearance grid measuring system can only be used for timesharing and show, can not be used for showing in real time and control.Existing digital display calliper resolution is 0.01mm, maximal rate 1.5m/s; When homemade digital display dial gauge resolution was 0.001mm, its speed dropped to 0.3m/s.The utility model can be brought up to micron order and submicron order with the resolution of holding the grid measuring system, and as digital display calliper resolution is brought up to 0.005mm, speed is brought up to 4m/s; When digital display dial gauge resolution was 0.0005mm, its speed was 0.8m/s.Also slide calliper rule can be made the digital display micrometer callipers, resolution reaches 0.001mm.In addition the utility model can also be directly used in digital control system with capacitor grid transducer.Use this digital display and measuring method can make the resolution of holding the grid measuring system bring up to 0.5 micron and 0.1 micron from 1 micron.

The utility model is used for digital display calliper and machine tool digital display unit, and linear measure longimetry resolution is 0.005mm, and measuring speed is 4m/s; The utility model is used for the digital display dial gauge in wide land, and linear measure longimetry resolution is 0.001mm and 0.005mm, and speed is 0.8m/s; The utility model also can be pressed into digital control system with the output pulse CP+ and the CP-of capacitor grid transducer.

Claims

1. adopt the appearance grid measurement mechanism of phase run and digitizer, it is characterized in that adopting real-time digital display circuit, amplitude, the frequency of sensor actuation signal are identical, and phase place is to differ 45 ° eight road square waves successively, and frequency of rectangular wave is clock f ₀The n frequency division, the displacement signal that receiving pole obtains is the phase-modulation wave identical with driving signal frequency, the phase modulation wave frequency also is that clock is transferred f ₀The n frequency division, n is the segmentation number that holds grid pitch τ, can select arbitrarily, the one-period of phase-modulated signal is a pitch holding grid, with the phase interpolation method pitch is carried out interpolation and segments, τ/n is the minimum step pitch of measuring system, from interpolation control circuit output terminal OUT ₁And OUT ₂Obtain real-time dfisplacement pulse, pulse equivalency is the minimum step pitch of displacement, and the frequency of output pulse is the speed of sensor displacement, and its rigid structure is: clock f ₀Be connected with frequency division driver, phase modulation frequency divider, interpolation control circuit, shaping synchronizer respectively, the frequency division driver is connected with sensor, sensor is connected to phase detector with prime amplifier, frequency-selecting amplifier, shaping synchronizer after connecting, the phase modulation frequency divider is connected with phase detector, interpolation control circuit respectively, and interpolation control circuit has two output terminal OUT ₁, OUT ₂, OUT ₁Output terminal links to each other with the phase modulation frequency divider; Output signal end OUT ₁And OUT ₂Output adds/subtracts count pulse CP+/CP-, OUT respectively ₁And OUT ₂Be connected to respectively numerical control CNC system also can, be connected to parallel again decoder driver, the LCD display of inserting behind the up-down counter.

2. the appearance grid measurement mechanism of employing phase run according to claim 1 and digitizer, it is characterized in that prime amplifier is connected in the following manner with frequency-selecting amplifier: sensor passes through capacitor C ₁With preamplifier IC ₁Anode connects, IC ₁Forward end connects resistance R simultaneously ₃, R ₃Connect resistance R respectively ₁And R ₂, R ₁Connect power supply, R ₂Ground connection; IC ₁Negative end connect resistance R respectively ₄, R ₅, R ₅Respectively with IC ₁Output terminal and capacitor C ₂Connect resistance R ₄Other end ground connection; Capacitor C ₂The other end connect capacitor C respectively ₃And resistance R ₆, R ₆Other end ground connection, C ₃The other end connect capacitor C respectively ₄, C ₅And resistance R ₇, R ₇Other end ground connection, C ₄Other end selecting audio amplifier IC respectively ₂Negative end and resistance R ₈, R ₈The other end meet IC respectively ₂Output terminal and C ₅, IC ₂Forward end ground connection.

3. the appearance grid measurement mechanism of employing phase run according to claim 1 and digitizer is characterized in that eight tunnel drive signals connect in the following manner: clock f ₀Insert trigger IC behind the frequency division 4/n ₄Input end of clock, IC ₄Q termination D end meet trigger IC again ₆Input end of clock, IC ₄Q termination trigger IC ₅Input end of clock, IC ₅Q termination IC ₆D end, meet trigger IC again ₇Input end of clock, IC ₅Q termination trigger IC ₈Input end of clock, IC ₆Q termination trigger IC ₉Input end of clock, IC ₆Q termination IC ₅D end meet trigger IC again ₁₀Input end of clock, IC ₇Q termination IC ₈D end, IC ₈Q termination IC ₇D end, IC ₉Q termination IC ₁₀D end, IC ₁₀Q termination IC ₉D end; IC ₇, IC ₈, IC ₉, IC ₁₀Q and Q end insert sensors as eight tunnel outputs.

4. the appearance grid measurement mechanism of employing phase run according to claim 1 and digitizer is characterized in that sensor output signal is through preamplifier IC ₁With frequency-selecting amplifier IC ₂Back shaping synchronousing circuit (6) is connected in the following manner with the circuit of phase modulation frequency divider (7): the phase-modulated signal of Displacement Measurement passes through capacitor C ₆Be connected to amplifier IC ₃Negative end, resistance R ₉Also be connected to IC ₃Negative end, R ₉Other end connecting resistance R ₁₀Connect power Vcc/2 again, R ₁₀Another termination IC ₃Forward end, resistance R ₁₁Meet IC ₃Forward end, R ₁₁Another termination IC ₃Output terminal, resistance R ₁₂Meet IC ₃Output terminal, R ₁₂Another termination power; IC ₃Output terminal meet trigger IC ₁₁D end, IC ₁₁Q termination IC ₁₂D end, be connected to Sheffer stroke gate IC again ₁₆Input end, trigger IC ₁₂Q end also be connected to trigger IC ₁₆Another input end, IC ₁₁And IC ₁₂Input end of clock meet clock f respectively ₀The input circuit connection of phase modulation frequency divider (7) is as follows: output terminal OUT ₁Be connected to trigger IC ₁₃Input end of clock, trigger IC ₁₃Q termination D end, OUT ₁Termination Sheffer stroke gate IC ₁₇Input end, IC ₁₃Q termination IC ₁₇Another input end, IC ₁₇Output termination Sheffer stroke gate IC ₁₈Input, Sheffer stroke gate IC ₂₆Output termination Sheffer stroke gate IC ₁₈Another input end, IC ₁₈Output signal be connected to trigger IC through 4/n frequency division rear end ₁₄Input end of clock, IC ₁₄Q termination D end, trigger IC ₁₅Input end of clock meet clock f ₀, Sheffer stroke gate IC ₁₉Input termination IC ₁₅Q end, IC ₁₉Another input termination IC ₁₅D end meet IC again ₁₄Q end, IC ₁₉Output terminal and IC ₁₆Output terminal insert respectively by Sheffer stroke gate IC ₂₀And IC ₂₁Two input ends of the comparer of forming 8; Sheffer stroke gate IC ₂₂, IC ₂₃, IC ₂₄, IC ₂₅Form interpolation control circuit, IC ₂₄Output terminal output positive-displacement pulse CP+, IC ₂₅Output terminal output negative sense dfisplacement pulse CP-.