CN1889134A - Structure of Object Proximity Detector and Position Detector - Google Patents

Abstract

The invention discloses a structure of an object approach detector and a position detector. An object approaching a sensor plate is detected by using the frequency variation of the oscillator. The frequency, which is a function of the process parameter (parameter), can be minimized by a compensation capacitor. The product does not need to be calibrated during manufacturing. To increase sensitivity, the sensing plate is placed in the feedback loop (feed back loop) of the oscillator. By adding the compensation capacitor and placing the sensing plate in the feedback loop, it is obtained that the sensitivity is increased and independent of the process parameters. A plurality of transmission gates (transmission gates) are connected to the input and output of the oscillator, and a sensing plate is connected to the transmission gates to form an object position detector.

Description

Object is near the structure of detector and position detector

Technical field

The present invention relates to the structure of a kind of object near detector and position detector, relate in particular to and a kind ofly be connected to the input and the outputs of oscillator with most transmission gates, sensory panel then is connected to the sensing object position device of transmission gate.

Background technology

The object in modern age is used to indicate an object how far to have from detector near detector and in order to measure object near detector.Generally being used for approaching detector is capacitive transducer (capacitivesensor) or inductance sensor (inductive sensor).Capacitive transducer changes into digital signal with changes in capacitance, and to judge whether reached effective capacitance, changes in capacitance and object are to the distance dependent of sensory panel.

There are many different existing methods to measure electric capacity between two sensory panels.One of them gives the change of amplifier in the measurement of output end AC signal of amplifier for present an AC signal via sensory panel.This technology is used in the United States Patent (USP) case number 5/374,787 of authorizing people such as Robert J.Miller; United States Patent (USP) case number 5/495,077 and United States Patent (USP) case number 5/841,078 and the United States Patent (USP) case number 5/914,465 of authorizing people such as Timothy P.Allen; United States Patent (USP) case number 6/239,389 B1; And the United States Patent (USP) case number 6/028,271 of authorizing people such as David W.Gillespie; United States Patent (USP) case number 6/610,936 B2.Utilize the system of this technology to comprise many mimic channels, as amplifier, wave filter, minimal value selector switch, subtracter, sampling/maintenance and A/D converter.The chip volume of mimic channel is big more than digit circuit in integrated circuit, and the reduction of unfavorable cost.The United States Patent (USP) case of giving method HaraldPhilip number 6/452, the technology of 514B1 is a kind of charge transfer circuit.In this circuit, the AC signal voltage source is added to one of sensory panel, and is fed to signal processor via another sheet of sensory panel.This signal processor comprises mimic channel, as peak sensing device, amplifier and A/D converter.The interference that is come by the RF signal will directly add to the peak sensing device, and be the source of system's detecting error.Other method is the input end connection sensory panel at oscillator.Electric capacity at the oscillator input end changes the change that will cause oscillator frequency.By the variation of detecting frequency, whether object is promptly detected out near sensory panel.This technology is used in United States Patent (USP) case number 6/583,676 B2 that authorizes people such as Christoph H.Krah.Oscillator frequency relevant with process parameter and electric power supply voltage.Object need be done frequency correction to compensate these variations near detector.As described in above-mentioned patent, prior art utilize two capacitors and resistor with the sensory panel at oscillator be object near or be that object is approaching judge.Because capacitor and resistor are manufactured all on the integrated circuit, be difficult to change and be difficult in the outside give sequencing near the sensitivity of detector.For avoiding that object is proofreaied and correct near the detector working frequency, need that oscillator of design makes frequency and process parameter and power supply supply relevant reduce to minimum.Foregoing invention increase an additional circuit to the system with of the influence of compensation processing procedure to oscillator.The RC oscillator that prior art is used always as shown in Figure 1.This circuit comprises three phase inverters 101,102,103, a resistance 104, a capacitor 106, a pair of sensory panel 105, the electric capacity of sensory panel is Cs, first order phase inverter 101 has Si Mite (Schmitt) and triggers (trigger) input, and the resistor 104 in the oscillator feedback loop is used for the charge/discharge assembly of circuit.The frequency of oscillator is by resistor 104 and 105,106 decisions of capacitor.The waveform of circuit as shown in Figure 2.Wherein VTR2 and VTR1 are the changing voltage (transfer voltage) that two Si Mite trigger input inverter 101.In the charge cycle (cycle) of circuit, when the voltage of the input end of phase inverter 101 arrived VTR2, the output of phase inverter 103 changed state (state) and circuit begins discharge cycle.The input end of first phase inverter 101 is through VTR2 and VTR1.The cycle of oscillator (period) be proportional to R (Cs+C1) (VTR2-VTR1)/(VCC-(VTR2+VTR1)/2)+dt, wherein dt is that the transmission (propagation) of phase inverter postpones (delay) and VCC is a power supply supply voltage.Formula thus, frequency is relevant greatly with changing voltage VTR2 and VTR1 as can be known.If circuit is with the CMOS process design, then the limit voltage of voltage difference VTR2-VTR1 and PMOS and NMOS (threshold voltage) matters a lot, if power supply supply voltage reduces, VTR2-VTR1 will reduce, and dt will increase, because propagation delay is very little in integrated circuit, the increase of dt is not enough to compensate the minimizing of VTR2-VTR1.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of sensing object position device, and the change of its sensitivity and process parameter is irrelevant.

Another technical matters that the present invention will solve is to provide a kind of sensing object position device, makes it have high sensitivity.

The technical problem to be solved in the present invention also is to provide a kind of object near detector, and the change of its sensitivity and process parameter is irrelevant.

Another technical matters that the present invention will solve also is to provide a kind of object near detector, makes it have high sensitivity.

For reaching above-mentioned purpose and other purpose, first viewpoint of the present invention provides the pierce circuit of a kind of object near detector and position detector.In circuit, a capacitor of setting up is added into.This capacitor is in order to add to the voltage swing (voltageswing) that Si Mite triggers the input end of phase inverter, and this voltage difference partly is proportional to supply voltage VCC, but has nothing to do with the PMOS of circuit and the limit voltage of NMOS two transistor.Two factors are cancelled each other, and make oscillator frequency be subjected to the influence of process parameter and power supply supply voltage to reduce to minimum.Except irrelevant with process parameter, the sensitivity of detector is also very important.If dCs is the capacitance variations of sensory panel among Fig. 1, the cyclomorphosis of oscillator is dT/T=dCs/ (C1+Cs), and then sensitivity is low.

Another viewpoint of the present invention provides a kind of sensory panel is connected to the input of oscillator and output terminal to increase sensitivity of method, sensitivity will increase a factor 2VCC/ (VTR2-VTR1) if VCC＞＞VTR2-VTR1, then the increase of sensitivity will be very high and highly sensitive characteristic irrelevant with process parameter can maintenance simultaneously in circuit by the advantage that combines two circuit.

In order to detect the approaching of object, object comprises an oscillator near detector, a pair of sensory panel, a counter (counter) and a microprocessor.In the detecting cycle of system, bring in constant renewal in params-count (reference count) N ₀This params-count is defined as in the count value of no object during near detector.And this params-count also is the maximum count value of ever recorded in counting process.

Default several Nr, but input microprocessor and in order to the definition sensitivity.In order to detect the approaching of object, counter calculates the frequency of oscillator, is Nx as if the value in (period) inside counting in certain period, N ₀-Nx can predict object near detector.When recording (N ₀-Nx)＞and Nr, promptly decidable has an object near this detector.Less Nr means sensitive system.Preceding method points out how to detect an object near detector.This technology can enlarge and improve detecting an object near detector array, and the detector of differentiating in which array detects.

Another preferred embodiment of the present invention provides a kind of sensing object position device.In order to design the sensing object position device, M transmission lock is connected in parallel in the input end of oscillator, and N transmission lock is connected in parallel in the output terminal of oscillator.The output terminal of these transmission locks can be in order to form M * N matrix.A pair of sensory panel forms a sense switch, and wherein a slice sensory panel can be connected to one of M transmission lock, and another sheet sensory panel can be connected to one of N transmission lock.The control grid (control gate) of these transmission locks is connected to the output terminal of microprocessor, and scans (scanned) in regular turn for microprocessor.Default several Nr can input to microprocessor and in order to define the sensitivity of each switch.The reference count N of each switch ₀Can be upgraded in scanning switch array (key matrix) time.If (N ₀-Nx)＞and Nr recorded when scanning the switch array, and promptly object of decidable is near certain switch in the switch array.Mimic channel of the present invention only comprises an oscillator and two transmission gate arrays.It is a lot of that the circuit of circuit of the present invention and prior art is compared simplification.

Above and other purpose of the present invention and advantage with reference to following with reference to icon and most preferred embodiment explanation and easilier understand fully.

Description of drawings

Fig. 1 is RC oscillator commonly used.

Fig. 2 is the function that the oscillator input terminal voltage of Fig. 1 changed the time.

Fig. 3 shows the oscillator circuit according to one embodiment of the invention,

Fig. 4 is the function that the oscillator input terminal voltage of Fig. 3 changed the time.

Fig. 5 is the pierce circuit according to another embodiment of the present invention.

Fig. 6 is the function that the oscillator input terminal voltage of Fig. 5 changed the time.

Fig. 7 is the circuit according to the characteristic with Fig. 3 and Fig. 5 of one embodiment of the invention.

Fig. 8 is the function that the oscillator input terminal voltage of Fig. 7 changed the time.

Fig. 9 is that object according to one embodiment of the invention is near detector.

Figure 10 has the object of power supply supply regulator near detector.

Figure 11 is the sensing object position device according to one embodiment of the invention.

Figure 12 is the sensing object position device with power supply supply regulator.

The main element symbol description

101 first order phase inverters, 102 second level phase inverters

103 third level phase inverters, 104 resistance R

105 sensory panels, 106 capacitor C1

201 first phase inverters, 202 second phase inverters

203 the 3rd phase inverters, 204 feedback resistor R

205 sensory panels, 206 first capacitor C1

207 compensation condenser C2,301 first phase inverters

302 second phase inverters 303 the 3rd phase inverter

304 resistance R, 305 sensory panels

306 capacitor C1,401 first phase inverters

402 second phase inverters 403 the 3rd phase inverter

404 resistance R, 405 sensory panel capacitor C s

406 capacitor C1,407 compensation condenser C2

501 tablets, 502 oscillator

503 time-base generators, 504 counters

505 microprocessors, 601 tablets

602 oscillator, 603 time-base generators

604 counters, 605 microprocessors

The input end of 606 power supplys supply regulator, 701 oscillators

Output terminal 703 oscillator of 702 oscillators

704 counters, 705 time-base generators

706 microprocessors, 801 oscillator input ends

Output terminal 803 oscillator of 802 oscillators

804 countings, 805 time-base generators

806 microprocessors, 807 power supplys supply regulator

Embodiment

Very useful in the application near to or in contact with a sensory panel (sensor plate) near (object proximity) detection techniques at object or finger.And position (object position) detection techniques is used when the position in the detecting array need be detected in object or finger.

Object of the present invention near one of circuit or sensing object position device embodiment comprise a pair of sensory panel, oscillator at least, base (time base) oscillator and a microprocessor one time.In many application, the frequency of oscillator and process parameter are irrelevant most important, and higher sensitivity also is sought after.Fig. 3 is for showing an oscillator circuit according to one embodiment of the invention, and this oscillator can compensate the factor that makes frequency shift because of the process parameter change.Fig. 4 is the function that the oscillator input terminal voltage of Fig. 3 changed the time.As shown in Figure 3, this oscillator comprises three phase inverters, first phase inverter 201, second phase inverter 202 and the 3rd phase inverter 203 serial connections; One first capacitor 206 is connected between the input and ground connection of this first phase inverter 201; A pair of sensory panel 205 also is connected between the input and ground connection of this first phase inverter 201; Compensation condenser 207 is connected between the output of the input of this first phase inverter 201 and second phase inverter 202; Feedback resistor 204 is connected between the output of the input of this first phase inverter 201 and the 3rd phase inverter 203; This feedback resistor 204 charges and discharge to this first capacitor 206, compensation condenser 207 and this sensory panel 205 in order to the input end at oscillator; This first phase inverter 201 has two transmission voltage VTR2 and VTR1.In the charged state transmission voltage is VTR2, in the discharge condition transmission voltage is VTR1, rise to the level of VTR2 at the voltage of the input end of first phase inverter 201, the output of first phase inverter 201 will change its state (state), after one period delivery time, the output of second phase inverter 202 also changes its state.The voltage of second phase inverter, 202 output terminals is beated (jump) will be via the input end of compensation condenser 207 to first phase inverters 201.The charging of the oscillator input end of Fig. 3 and the voltage range of discharge comprise three partly.First is VTR2-VTR1 partly; Second partly for to be caused by compensation condenser 207, is 2VCC (C2/ (C1+C2+Cs)); The 3rd is partly caused that by transmitting through phase inverter 201,202 and 203 if limit voltage increases, VTR2-VTR1 will reduce.Because the phase inverter internal resistance increases with the increase of limit voltage, if limit voltage increases, then the charge or discharge electric current will reduce.Therefore, if limit voltage increases, the duration of charging of VTR2-VTR1 must reduce, and the duration of charging of 2VCC (C2/ (C1+C2+Cs)) will increase and propagation delay also will increase.By suitable selection capacitor 205,206 and 207, the time cycle of oscillator will reduce to minimum with the influence that process parameter changes.Therefore the frequency of oscillator is subjected to the influence of process parameter will reduce to minimum.Then the calibration to oscillator does not need when making.

The pierce circuit of another embodiment of the present invention as shown in Figure 5.And the function that the oscillator input terminal voltage changed the time as shown in Figure 6.In this circuit, a pair of sensory panel 305 is connected between the output of the input of first phase inverter 301 and the 3rd phase inverter 303; In this circuit, be VCC in the voltage transition amplitude of the 3rd phase inverter 303 output, change into dT/T=(dCs/ (Cs+C1)) (2VCC/ (VTR2-VTR1)) by what the change of sense capacitance made the time cycle.Compare as the oscillatory circuit with Fig. 1, the sensitivity of Fig. 5 is exaggerated 2VCC/ (VTR2-VTR1) doubly.

In order to improve oscillation frequency simultaneously with the influence of process parameter change and the sensitivity of increase detector, the advantage of Fig. 3 and Fig. 5 can combine.Circuit with this characteristic as shown in Figure 7.And the function that the oscillator input terminal voltage changed the time as shown in Figure 8.In this circuit, sensory panel 405 is connected between the input of the output of the 3rd phase inverter 403 and first phase inverter 401; Compensation condenser 407 is connected between the input of the output of second phase inverter 402 and first phase inverter 401; The effect of compensation condenser 407 is offseted the electric capacity of part by sensory panel 405.If consider the charging time-histories (charging range) of phase inverter 401 input ends, the capacitor C 2 of compensation condenser 407 must be bigger than the capacitor C s of sensory panel 405.By the electric capacity of suitable selection capacitor 405,406 and 407, oscillation frequency can be reduced to minimum with the influence that process parameter changes.

The above circuit of the present invention is to be used for the oscillator of object near detector or sensing object position device.Object near detector comprise a pair of sensory panel, oscillator at least, base (time base) oscillator, a counter and a microprocessor one time.System shown in Figure 9 is that object according to one embodiment of the invention is near detector.Among Fig. 9, system comprises a pair of sensory panel 501, is connected to 503, one counters 504 of 502, one time-base generators of an oscillator and a microprocessor 505.Oscillator 502 is the circuit of above-mentioned Fig. 3, Fig. 5 or Fig. 7 with sensory panel 501.Time-base generator 503 provides system's clock pulse to microprocessor 505.During system's detecting, store a reference count N ₀In microprocessor 505, and upgrade at any time.This reference count is defined as the count value when not having object near sensory panel 501, and reference count also is the maximal value of once counting in the counting procedure.Default value Nr can input to microprocessor 505 and in order to the sensitivity of definition object near sensory panel.In order to detect the approaching of an object, counter 504 calculates the frequency of oscillator 502, if be Nx in scheduled period inside counting value, and N ₀Whether-Nx can measure an object near sensory panel 501.As (N ₀-Nx)＞and Nr is measured, and promptly object of decidable is near sensory panel 501.Less Nr means sensitive system.Import different Nr to microprocessor 505, object can be controlled (programmed) by the outside near the sensitivity of detector.

Oscillator frequency is subjected to the influence of power supply supply voltage and changes.For promoting the stability of object near detector, the system with power supply supply regulator 606 is shown in Figure 10.The power supply supply of oscillator 602 and time-base generator 603 is provided by power supply supply regulator 606.Improve thus, system can stablize and the acquisition high sensitivity.

Said method points out how to detect an object near detector.This technology can enlarge and modify with an object detects array near one, and resolution which detector in array is detected.This system is referred to as the sensing object position device.

Figure 11 is sensing object position device one embodiment.In this circuit, have M transmission lock (761-76M) to be connected in parallel in the input end 701 of oscillator 703, and N transmission lock (781-78N) is connected in parallel in the output terminal 702 of oscillator 703.The output terminal of these transmission locks can be in order to form M * N matrix.Form a detector, a slice that can connect sensory panel is to one of M transmission lock (731-73M), and another sheet sensory panel can be connected to one of N transmission lock (741-74N).The control grid (711-71N and 721-72M) of these transmission locks (781-78N and 761-76M) is connected to the output terminal (711-71N and 721-72M) of microprocessor 706, and is that microprocessor 706 scans (scanned) in regular turn.Default several Nr can input to microprocessor 706 and in order to the sensitivity of definition by each switch of tablet.The reference count N of each switch ₀Can be upgraded in scanning switch array (key matrix) time.If (N ₀-Nx)＞and Nr recorded when scanning the switch array, and promptly object of decidable is near the some switches in the switch array.

The frequency stability of the oscillator in the sensing object position device also can be improved by setting up a power supply supply regulator.Figure 12 is the sensing object position device with power supply supply regulator 807.This power supply supply regulator 807 is supplied to oscillator 803 and time-base generator 805 in order to power supply to be provided.The output voltage of power supply supply regulator 807 does not change because of the variation of power supply supply voltage, so the frequency stabilization of oscillator 803 and 805 can be kept.With this understanding, less Nr can be input to microprocessor 806 to obtain higher sensitivity.

By the detailed description of above preferable specific embodiment, be to wish know more to describe feature of the present invention, and be not to come category of the present invention is limited with above-mentioned disclosed preferred embodiments with spiritual.Opposite, its objective is that hope can contain in the patent category of being arranged in of various changes and tool equality institute of the present invention desire application.

Claims (12)

1. An object proximity detector, comprising a pair of sensing plates connected to a sensing oscillator for detecting the approach of an object by a change in capacitance; a sensing oscillator, the change in capacitance makes the sensing oscillator frequency change, the output of the sensing oscillator is connected to the input of a counter; a counter counts the frequency of the sensing oscillator, the output of which communicates with a microprocessor; a time base oscillator provides the system time of the microprocessor Pulse, a microprocessor, calculates and processes the frequency from the counter to determine that an object is approaching the detector; the improvements include at least: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground a pair of sense plates are also connected between the input of the first inverter and ground; a compensation capacitor is connected between the input of the first inverter and the output of the second inverter; a feedback resistor connected between the input of the first inverter and the output of the third inverter; the feedback resistor is used to charge and discharge the first capacitor, the compensation capacitor and the sensing plate at the input of the oscillator; The first inverter is an inverter with a Schmitt trigger input; the compensating capacitor is used to reduce the influence of oscillation frequency changing with process parameters. 2. The object proximity detector according to claim 1, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable. 3. An object proximity detector, comprising a pair of sensing plates connected to a sensing oscillator to detect the approach of an object by a change in capacitance; a sensing oscillator, the change in capacitance makes the sensing oscillator frequency change, the output of the sensing oscillator is connected to the input of a counter; a counter counts the frequency of the sensing oscillator, the output of which communicates with a microprocessor; a time base oscillator provides the system time of the microprocessor Pulse, a microprocessor, calculates and processes the frequency from the counter to determine that an object is approaching the detector; the improvements include at least: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground ; A pair of sense plates are also connected between the input of the first inverter and the output of the third inverter; a feedback resistor is connected between the input of the first inverter and the third inverter between the outputs of the oscillator; the feedback resistor is used to charge and discharge the first capacitor and the sensing plate at the input of the oscillator; the first inverter is an inverter with a Schmitt trigger input; the sensing The connection of the test board is used to increase the sensitivity of the object proximity detector. 4. The object proximity detector as claimed in claim 3, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable. 5. An object proximity detector comprising a pair of sensing plates connected to a sensing oscillator for detecting the approach of an object by a change in capacitance; frequency change, the output of the sensing oscillator is connected to the input of a counter; a counter counts the frequency of the sensing oscillator, the output of which communicates with a microprocessor; a time base oscillator provides the system time of the microprocessor Pulse, a microprocessor, calculates and processes the frequency of the counter to determine that an object is close to the detector; the improvements include at least: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground ; A pair of sensing plates are connected between the input of the first inverter and the output of the third inverter; a compensation capacitor is connected between the input of the first inverter and the output of the second inverter between; a feedback resistor is connected between the input of the first inverter and the output of the third inverter; the feedback resistor is used for the first capacitor, the compensation capacitor and the inductor The test board is charged and discharged; the first inverter is an inverter with a Schmitt trigger input; the compensation capacitor is used to reduce the influence of the oscillation frequency as the process parameter changes, and the connection of the sensing board is used to increase the The sensitivity of the proximity detector. 6. The object proximity detector as claimed in claim 5, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable. 7. An object position detector, comprising a sensing oscillator; a time base oscillator, providing the system clock of the microprocessor, a counter, counting the frequency of the sensing oscillator, and its output is connected with a microprocessor A row of transmission gates is connected to the input of the sensing oscillator; a column of transmission gates is connected to the output of the sensing oscillator; the row of transmission gates and the column of transmission gates form a switch matrix; each of the switch matrix The switch is formed by a pair of sense plates, with the output of one sense plate connected to the input of the sense oscillator through the transmission gate; and the output of the other sense plate connected to the output of the sense oscillator through the transmission gate. The control gate of the transmission gate is scanned by a microprocessor; a microprocessor calculates and processes the frequency of the counter to determine that one or more objects are close to a certain pair of sensing plates of the detection array to determine a or the positions of multiple objects in the detection array; the improvements at least include: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground a pair of sense plates are also connected between the input of the first inverter and ground; a compensation capacitor is connected between the input of the first inverter and the output of the second inverter; a feedback resistor connected between the input of the first inverter and the output of the third inverter; the feedback resistor is used to charge and discharge the first capacitor, the compensation capacitor and the sensing plate at the input of the oscillator; The first inverter is an inverter with a Schmitt trigger input; the compensating capacitor is used to reduce the influence of oscillation frequency changing with process parameters. 8. The object position detector as claimed in claim 7, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable. 9. An object position detector comprising a sensing oscillator; a time base oscillator providing the system clock of the microprocessor, a counter counting the frequency of the sensing oscillator, the output of which is connected to a microprocessor A row of transmission gates is connected to the input of the sensing oscillator; a column of transmission gates is connected to the output of the sensing oscillator; the row of transmission gates and the column of transmission gates form a switch matrix; each of the switch matrix The switch is formed by a pair of sense plates, with the output of one sense plate connected to the input of the sense oscillator through the transmission gate; and the output of the other sense plate connected to the output of the sense oscillator through the transmission gate. ; The control gate of the transmission gate is scanned by a microprocessor; A microprocessor calculates and processes the hungry frequency of the counter to determine that one or more objects are close to a certain pair of sensing plates of the detection array to determine a or the positions of multiple objects in the detection array; the improvements include at least: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground ; A pair of sense plates are also connected between the input of the first inverter and the output of the third inverter; a feedback resistor is connected between the input of the first inverter and the third inverter between the outputs of the oscillator; the feedback resistor is used to charge and discharge the first capacitor and the sensing plate at the input of the oscillator; the first inverter is an inverter with a Schmitt trigger input; the sensing The connection of the test board is used to increase the sensitivity of the object proximity detector. 10. The object position detector as claimed in claim 9, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable. 11. An object position detector comprising a sensing oscillator; a time base oscillator providing the system clock of the microprocessor, a counter counting the frequency of the sensing oscillator, and its output is connected to a microprocessor A row of transmission gates is connected to the input of the sensing oscillator; a column of transmission gates is connected to the output of the sensing oscillator; the row of transmission gates and the column of transmission gates form a switch matrix; each of the switch matrix The switch is formed by a pair of sense plates, with the output of one sense plate connected to the input of the sense oscillator through the transmission gate; and the output of the other sense plate connected to the output of the sense oscillator through the transmission gate. The control gate of the transmission gate is scanned by a microprocessor; a microprocessor calculates and processes the frequency of the counter to determine that one or more objects are close to a certain pair of sensing plates of the detection array to determine a or the positions of multiple objects in the detection array; the improvements include at least: The sensing oscillator includes three inverters, the first inverter, the second inverter and the third inverter are connected in series; a first capacitor is connected between the input of the first inverter and the ground ; A pair of sensing plates are connected between the input of the first inverter and the output of the third inverter; a compensation capacitor is connected between the input of the first inverter and the output of the second inverter between; a feedback resistor is connected between the input of the first inverter and the output of the third inverter; the feedback resistor is used for the first capacitor, the compensation capacitor and the inductor The test board is charged and discharged; the first inverter is an inverter with a Schmitt trigger input; the compensation capacitor is used to reduce the influence of the oscillation frequency as the process parameter changes, and the connection of the sensing board is used to increase the The sensitivity of the proximity detector. 12. The object position detector as claimed in claim 11, further comprising: A power supply regulator is connected to the sensing oscillator and the time base oscillator to keep the sensing oscillator and the time base oscillator stable.

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