CN201731889U - Power-transformation medium capacitance type sensing device for measuring rolling reduction oscillation of keys - Google Patents

Abstract

A power-transformation medium capacitance type sensing device for measuring rolling reduction oscillation of keys comprises a capacitance sensor (1), a physical conversion circuit (2) and a digital rolling reduction detecting circuit (3), wherein the capacitance sensor (1) is installed below keys (4), the movement of the keys (4) drives a dielectric medium plate (2-2) of the capacitance sensor (1) to move so as to result in the capacitance change of the capacitance sensor (1), and the physical conversion circuit (2) formed on the basis of the capacitance sensor (1) converts the capacitance change of the capacitance sensor (1) into the change of rectangular wave pulse width, the digital rolling reduction detecting circuit measures the pulse width of the rectangular wave signals of the physical conversion circuit (2) so as to obtain the related information of the rolling reduction of the keys. The utility model provides a non-contact digital device for acquiring the disc force of the electronic organ keys in real time, the sensing device is simple in structure, low in cost and high in precision, has the capability of simulating the key stroke force and string rub, and provides effective support for a high-performance electronic organ.

Description

Variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device

Technical field

The utility model relates to a kind of non-contacting digital electronic piano key board dynamics real-time acquisition device, has provided a kind of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device more specifically.

Background technology

The sounding principle of electronic musical instrument is different from general musical instrument, and the electric signal that it produces with the electroacoustic combiner circuit is as sound generation source, and voiced process is controlled by all multiparameters.For mellotron, need special keyboard Acquisition Circuit to gather the voiced process of keyboard playing information with control electroacoustic compositor, the power of electroacoustic building-up process middle pitch, enveloping curve length, to rub string amplitude etc. all relevant with player's keystroke dynamics, and therefore fine and smooth in real time key dynamics is measured and can be improved electronic musical instrument effectively and enrich careful expressive force.

Along with development of electronic technology, the ability of electronic musical instrument constantly strengthens, the playing effect of the simulation general physics sounding musical instrument that the high-end electronic musical instrument of part can be true to nature, and also the musical performance form of electronic musical instrument is abundant, no longer is confined to the conventional keyboard mode.From the angle of simulating common musical instrument and the angle of creating new musical instrument, collection has proposed new requirement to high-end electronic musical instrument to the key dynamics.Play the problem of control and the collection of key dynamics in order to solve electronic musical instrument at present, following several solutions occurred.

1, mechanical switch method

The related system of mechanical switch method that the electronic organ key dynamics is gathered is made up of the auxiliary circuit of two above mechanical switchs and cooperation with it.Mechanical switch adopts conductive rubber, Hall switch or reed structure.Its method is, calculates the average velocity of pressing key motion by the mistiming of measurement mechanical switch closure, utilizes this average velocity to represent the key dynamics approx.This method is simple in structure, cost is low, but still has defective: at first, low and dynamics one-touch of measuring accuracy can only be measured once, has only button to press once more just and can measure next time; Secondly, the life-span of key is short, and materials such as conductive rubber and reed are long-time to use easy oxidation to be out of shape; At last, there is shake in mechanical switch, and the shake during switch closure will influence key dynamics acquisition quality.

2, force-sensing sensor method

The related system of force-sensing sensor method that the electronic organ key dynamics is gathered is made up of the auxiliary circuit of dynamics sensor and cooperation with it.Dynamics sensor adopts pressure sensor, foil gauge or resistance rubber.Wherein pressure transducer is divided into pressure resistance type, inductance type, condenser type, resonant mode etc. again, and foil gauge is divided into resistance-type and semiconductor-type, and resistance rubber is a kind of resilient material, and the back that is under pressure produces deformation, and power large deformation more is big more, and corresponding resistance is big more.The ultimate principle of force-sensing sensor method is exactly by the dynamics sensor and the auxiliary circuit that cooperates with it, and the pressure after key is pressed is reflected on the output electric signal of sensing circuit, the output electric signal difference of the different sensing circuits of pressure.This method measuring accuracy height, but still have defective: at first, the cost of pressure transducer is higher, and auxiliary sensing circuit structure is complicated, and pressure information will pass through the multi-level pmultistage circuit treatment conversion, and expensive and complex structure has brought difficulty to realization; Secondly, the dynamics information that this method is measured can only reflect the pressure information after key is pressed, and can not reflect that key pushes the pressure information in the process.

3, magneto-dependent sensor method

The related system of magneto-dependent sensor method that the electronic organ key dynamics is gathered is made up of the auxiliary circuit of electromagnetic sensor and cooperation with it.Electromagnetic sensor is made up of the magnet and the sensing coil that are installed under the key.The ultimate principle of magneto-dependent sensor method is exactly to utilize the voltage-level detector that links to each other with sensing coil to measure the key dynamics.The rate of change of magnetic flux is directly proportional with the rate of change of key speed in the coil, and keystroke dynamics is proportional to the induction electromotive force of coil, by the real-time keystroke dynamics of induction electromotive force reflection of coil.But also there is defective in this method: at first, the narrow and small coil distance that causes in key inner space is very near, is easy to generate interference between sensor; Secondly, the pressure signal of detection still is a simulating signal, and the volume of coil is subject to the structure of key, has influenced measuring accuracy; At last, Fu Za translation circuit has brought difficulty for this method in realization.

In sum, all there is inevitable defective in present existing the whole bag of tricks when having the particular performances advantage.Existing each method all can not solve the problem that complex structure, cost height, life-span are limited, be subject to disturb simultaneously, and existing each method is measured the ability of piano key rolling reduction when not possessing high-precision real.

Summary of the invention

The purpose of this utility model is to propose novel contactless piano key rolling reduction and measures sensing device in real time, is specifically related to a kind of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Utilize the problem that this contactless, real-time sensing device solves piano key rolling reduction measurement structure complexity, precision is low, cost is high, the life-span is limited, be subject to disturb.

Variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model comprises capacitive transducer (1), physical transformation circuit (2) and digital drafts testing circuit (3), capacitive transducer (1) is installed in key (4) below, the dielectric plate (2-2) of key (4) moving belt dynamic condenser sensor (1) moves and causes the capacitance variations of capacitive transducer (1), the physical transformation circuit (2) that constitutes based on capacitive transducer (1) is converted to the square wave pulse width variation with the capacitance variations of capacitive transducer (1), and the pulse width that digital drafts testing circuit (3) is measured the square-wave signal of physical transformation circuit (2) obtains the relevant information of piano key rolling reduction.

The related capacitive transducer (1) of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model is made up of negative capacitance pole plate (2-1), positive capacitor plate (2-3) and dielectric plate (2-2); Negative capacitance pole plate (2-1) is positioned at the outermost both sides of capacitive transducer (1), and positive capacitor plate (2-3) is positioned between the negative capacitance pole plate (2-1), and dielectric plate (2-2) is positioned between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3); Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) are fixed on the pedestal wiring board (6-1) equidistant parallel discharging; Dielectric plate (2-2) is fixed in key (4) below, equidistant parallel discharging; Dielectric plate after the installation (2-2) is parallel to be interspersed between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3), constitutes dielectric plate (2-2) with respect to negative capacitance pole plate (2-1) and the positive parallel mobile bar structure of capacitor plate (2-3).Because intert a dielectric plate (2-2) between positive capacitor plate of each piece (2-3) and the negative capacitance pole plate (2-1), make that a positive capacitor plate (2-3) can corresponding two negative capacitance pole plates (2-1), so the electric capacity of capacitive transducer (1) will promote one times, measure sensitivity and double.

The circuit connecting mode of the capacitive transducer (1) that variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model is related is: positive terminal (6-2) links to each other with the positive capacitor plate (2-3) of capacitive transducer (1), negative terminals (6-3) links to each other with the negative capacitance pole plate (2-1) of capacitive transducer (1), because positive capacitor plate (2-3) and negative capacitance pole plate (2-1) are fixed on the pedestal wiring board (6-1), so positive terminal (6-2) and negative terminals (6-3) can use the form of PCB circuit to be laid on the pedestal wiring board (6-1), this has structurally guaranteed the simplification of processing and the stability of system, negative terminals (6-3) is wanted ground connection after installing, negative terminals (6-3) ground connection makes that the corresponding capacitive transducer (1) of adjacent two keys (4) can shared same negative capacitance pole plate (2-1), simplify the structure, simultaneously, the ground connection that is positioned at the outermost negative capacitance pole plate (2-1) of capacitive transducer (1) has been played the anti-interference effect of shielding to capacitive transducer (1).

The measuring principle of the capacitive transducer (1) that variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model is related is: when key is not depressed, and the initial capacitance C of capacitive transducer (1) ₀Can equivalence be two capacitor C ₁₀And C ₂₀Parallel connection, C ₁₀Be to be dielectric electric capacity with dielectric plate (2-2), C ₂₀Be to be dielectric electric capacity with air, the initial capacitance C of capacitive transducer (1) ₀Computing formula as follows:

${\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="HSA00000124381200041.png"\; state="\{\{state\}\}">C</figure-callout>}}_0=C_{10}+C_{20}={\mathrm{\&xi;}}_r{\mathrm{\&xi;}}_0\frac{A_{10}}{d}+{\mathrm{\&xi;}}_0\frac{A_{20}}{d}=\frac{({\mathrm{\&xi;}}_r{A}_{10}+A-A_{10})}{A}\&times;{\mathrm{\&xi;}}_0\&times;\frac{A}{d}={\mathrm{\&xi;}}_{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HSA00000124381200041.png"\; state="\{\{state\}\}">r</figure-callout>}0}^{\&prime;}\frac{A}{d},A_{10}+A_{20}=A$

ξ wherein _rBe the relative dielectric constant of dielectric plate (2-2) with respect to air dielectric, ξ ₀Be the specific inductive capacity of air dielectric,

Be the equivalent dielectric coefficient of capacitive transducer (1) when key is not depressed, d is the distance between plates of negative capacitance pole plate (2-1) with the positive capacitor plate (2-3) of capacitive transducer (1), A be capacitive transducer (1) negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, A ₁₀Be capacitor C ₁₀Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, A ₂₀Be capacitor C ₂₀Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area.When key was depressed, dielectric plate (2-2) extend between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3), the displaced air dielectric.The capacitor C of capacitive transducer (1) just equivalence is C ₁And C ₂Parallel connection, C ₁Be key to depress the back be dielectric electric capacity with dielectric plate (2-2), C ₂Be key to depress the back be dielectric electric capacity with air, the computing formula of the capacitor C of capacitive transducer (1) after key is depressed is:

$C={\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000124381200041.png,HSA00000124381200061.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HSA00000124381200011.png"\; state="\{\{state\}\}">C</figure-callout>}}_2={\mathrm{\&xi;}}_r{\mathrm{\&xi;}}_0\frac{A_1}{d}+{\mathrm{\&xi;}}_0\frac{A_2}{d}={\mathrm{\&xi;}}_r{\mathrm{\&xi;}}_0\frac{A_{10}+\mathrm{\&Delta;A}}{d}+{\mathrm{\&xi;}}_0\frac{A_{20}-\mathrm{\&Delta;A}}{d}={\mathrm{<figure-callout\; id="0"\; label="C"\; filenames="HSA00000124381200041.png"\; state="\{\{state\}\}">C</figure-callout>}}_0+\frac{{\mathrm{\&xi;}}_0\mathrm{\&Delta;A}}{d}({\mathrm{\&xi;}}_r-1)$

$={\mathrm{\&xi;}}_{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HSA00000124381200041.png"\; state="\{\{state\}\}">r</figure-callout>}0}^{\&prime;}\frac{A}{d}+\frac{{\mathrm{\&xi;}}_0({\mathrm{\&xi;}}_r-1)\mathrm{\&Delta;A}}{A}\&times;\frac{A}{d}=({\mathrm{\&xi;}}_{\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="HSA00000124381200041.png"\; state="\{\{state\}\}">r</figure-callout>}0}^{\&prime;}+\frac{{\mathrm{\&xi;}}_0({\mathrm{\&xi;}}_r-1)\mathrm{\&Delta;A}}{A})\&times;\frac{A}{d}={\mathrm{\&xi;}}_r^{\&prime;}\frac{A}{d}$

$\mathrm{\&Delta;A}\&Element;[0,L-A_{10}],{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="HSA00000124381200041.png,HSA00000124381200061.png"\; state="\{\{state\}\}">A</figure-callout>}}_1=A_{10}+\mathrm{\&Delta;A},{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="HSA00000124381200011.png"\; state="\{\{state\}\}">A</figure-callout>}}_2=A_{20}-\mathrm{\&Delta;A},{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="HSA00000124381200041.png,HSA00000124381200061.png"\; state="\{\{state\}\}">A</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="HSA00000124381200011.png"\; state="\{\{state\}\}">A</figure-callout>}}_2=A$

ξ wherein _rBe the relative dielectric constant of dielectric plate (2-2) with respect to air dielectric, ξ ₀Be the specific inductive capacity of air dielectric,

Be the equivalent dielectric coefficient of capacitive transducer (1) when key is not depressed,

Be the equivalent dielectric coefficient of capacitive transducer (1) when key is depressed, d is the distance between plates of negative capacitance pole plate (2-1) with the positive capacitor plate (2-3) of capacitive transducer (1), A be capacitive transducer (1) negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, A ₁Be capacitor C ₁Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, A ₂Be capacitor C ₂Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, L be dielectric plate (2-2) with the maximum of negative capacitance pole plate (2-1) and positive capacitor plate (2-3) over against area, Δ A is A after dielectric plate (2-2) moves ₁With respect to A ₁₀Variation.Can obtain the equivalent dielectric coefficient of capacitive transducer (1) by the computing formula of the capacitor C of capacitive transducer (1) after key is depressed

Because the negative capacitance pole plate (2-1) of capacitive transducer (1) and the positive stationkeeping of capacitor plate (2-3) on pedestal wiring board (6-1), so negative capacitance pole plate (2-1) and positive capacitor plate (2-3) all is constant over against area A and distance between plates from d.And the electric capacity computing formula of capacitor is

According to Just know, when key is not depressed, the equivalent dielectric coefficient of capacitive transducer (1)

Be constant, the electric capacity of capacitive transducer (1) does not change.When key was depressed, dielectric plate (2-2) extend into the variation that produces Δ A between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3), the equivalent dielectric coefficient ξ of capacitive transducer (1) _r' become a changing value, promptly the electric capacity of capacitive transducer (1) becomes the changing value of reflection piano key rolling reduction.

The related physical transformation circuit (2) of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model adopts auto-excitation type rectangle wave generation circuit (3-1) or separated exciting rectangle wave generation circuit (4-1); Auto-excitation type rectangle wave generation circuit (3-1) utilizes the square wave oscillation circuit that constitutes based on capacitive transducer (1) capacitance variations of capacitive transducer (1) to be converted to the variation in square wave cycle; Separated exciting rectangle wave generation circuit (4-1) utilizes the threshold voltage comparator circuit that constitutes based on capacitive transducer (1) that the capacitance variations of capacitive transducer (1) is changed the variation of the charging rise time (4-3) of capacitive transducer (1), and the square wave that discharges and recharges of capacitive transducer (1) is provided by digital drafts testing circuit (3) in the separated exciting rectangle wave generation circuit (4-1).

Capacitive transducer (1) is converted into capacitance change with piano key rolling reduction, and the digital drafts testing circuit (3) that carries out drafts measurement and processing can not directly be measured electric capacity, so need capacitance change to be converted to the square-wave signal amount, make the real-time measurable square-wave signal amount of reflection numeral drafts testing circuit (3) of piano key rolling reduction by physical transformation circuit (2).When physical transformation circuit (2) adopted auto-excitation type rectangle wave generation circuit (3-1), there was following corresponding relation in the cycle of the square-wave signal (3-2) of the electric capacity of capacitive transducer (1) and physical transformation circuit (2) output:

T∝R ₃C

Wherein T is the cycle of square-wave signal (3-2), and C is the electric capacity of capacitive transducer (1), R ₃It is loop resistance.The electric capacity of capacitive transducer (1) is proportional to the cycle of the square-wave signal (3-2) of physical transformation circuit (2) output.When key was depressed, the electric capacity of capacitive transducer (1) changed, and the cycle of square-wave signal (3-2) also changes accordingly.When physical transformation circuit (2) adopted separated exciting rectangle wave generation circuit (4-1), the electric capacity of capacitive transducer (1) had following corresponding relation with charging rise time (4-3):

Tr∝R ₁C

Wherein Tr is the charging rise time (4-3), and C is the electric capacity of capacitive transducer (1), R ₁It is loop resistance.The electric capacity of capacitive transducer (1) is proportional with charging rise time (4-3).Charging rise time (4-3) is meant that providing pumping signal from digital drafts testing circuit (3) surpasses comparator threshold voltage institute elapsed time to capacitive transducer (1) charging.When key was depressed, the capacitance variations of capacitive transducer (1) was reflected in the variation of charging rise time (4-3).With respect to auto-excitation type rectangle wave generation circuit (3-1), separated exciting rectangle wave generation circuit (4-1) has the advantage of equal interval sampling.Two kinds of implementations of physical transformation circuit (2) all use comparer as the core conversion element.Adopt comparator circuit to make that the cost of physical transformation circuit (2) is very low, simple for structure, help manufacturing, higher precision has been guaranteed in stable simultaneously pulse output.Capacitance variations is converted into digital signal has also improved the antijamming capability of measuring.

The related digital drafts testing circuit (3) of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device of the present utility model is realized by the FPGA/CPLD circuit.Numeral drafts testing circuit (3) measures piano key rolling reduction by the pulse width that detects physical transformation circuit (2) output square wave.Piano key rolling reduction is carried out secondary data handle, degree of testing the speed, correction in real time measured to realize key keystroke dynamics, and location moves, proofreaies and correct to realize rubbing the string analog functuion in real time.Numeral drafts testing circuit (3) is done linearity or non-linear drafts correction by the characteristic correction link to the data of gathering according to parameter setting, regulates and gathers characteristic to reach the keystroke dynamics and to rub the requirement that string is simulated.Numeral drafts testing circuit (3) also needs to discharge and recharge the square wave pumping signal for capacitive transducer (1) provides when physical transformation circuit (2) adopts separated exciting rectangle wave generation circuit (4-1).Numeral drafts testing circuit (3) has been introduced the advantage of digital processing, the processing of the high precision that has realized piano key rolling reduction is measured, high-speed, high complexity.

The utility model is with respect to the advantage of prior art:

1, compared with prior art, the utlity model has non-contacting characteristics, non-cpntact measurement makes sensor element not have friction work, has prolonged the life-span of sensor element, and noncontact has simultaneously also overcome jitter problem.

2, compared with prior art, the utlity model has the characteristics of real-time measurement.The piano key rolling reduction information of gathering has reflected the motion process of key in real time.

3, compared with prior art, sensor element and physics conversion circuit that the utility model adopts have cost advantage low, simple for structure, do not need to use expensive survey sensor and modulus switching device, reduced the cost and the complexity that realize, for the manufacturing is provided convenience.

4, compared with prior art, the utility model has adopted digital signal processing method, and measuring system has been introduced the method for digital processing, the advantage of having brought high precision, high-speed, high complexity to handle.

5, compared with prior art, the utility model has promoted antijamming capability.Negative capacitance pole plate (2-1) ground connection of capacitive transducer (1), and be placed on outermost and play shielding action, the structure that capacitor plate position and cabling are fixing has promoted the antijamming capability of sensor element.

6, compared with prior art, the utlity model has higher precision, the resolution that can reach is higher than 1% piano key rolling reduction measurement, has very fine and smooth musical expression.

7, compared with prior art, the utility model support uniqueness rubs the string playing mode.What the mode of setting up the tuning wheel separately that adopts traditional keyboard realized musical instrument rubs the string function, and the utility model then directly adopts real-time piano key rolling reduction as rubbing the string controlled quentity controlled variable, produces and rubs the effect that string is played, and has higher stringed musical instrument analog capability.

Sum up above-mentioned advantage, the utility model has solved the problem that can not have low cost, low difficulty of processing, long life, high precision, high anti-jamming capacity simultaneously that existing method exists, and has also proposed to innovation simultaneously to utilize real-time piano key rolling reduction to rub the new performance pattern of string control.

Description of drawings

Fig. 1 is a variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device structured flowchart.

Fig. 2 is the related capacitor sensor structure figure of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Fig. 3 is related auto-excitation type rectangle wave generation circuit and an oscillogram thereof of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Fig. 4 is related separated exciting rectangle wave generation circuit and an oscillogram thereof of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Fig. 5 is the related digital drafts testing circuit block diagram of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Fig. 6 is the related wiring layout of capacitive transducer in key of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Fig. 7 is the related capacitive transducer assembling wiring diagram of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.

Number in the figure: 1 is capacitive transducer, and 2 is the physical transformation circuit, and 3 is digital drafts testing circuit, and 4 is key, and 5 is the electroacoustic compositor; 2-1 is the negative capacitance pole plate, and 2-2 dielectric plate, 2-3 are positive capacitor plate; 3-1 is an auto-excitation type rectangle wave generation circuit, and 3-2 is the square-wave signal of auto-excitation type rectangle wave generation circuit output; 4-1 is a separated exciting rectangle wave generation circuit, and 4-2 is the driving source of digital drafts testing circuit (3) output, and 4-3 is the charging rise time; 6-1 is the pedestal wiring board, and 6-2 is a positive terminal, and 6-3 is a negative terminals.

Specific implementation method

Be described in further detail as follows with embodiment to ins and outs of the present utility model in conjunction with the accompanying drawings.

Fig. 1 is a variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device structured flowchart.Shown sensing device comprises capacitive transducer (1), physical transformation circuit (2) and digital drafts testing circuit (3), capacitive transducer (1) is installed in key (4) below, the dielectric plate (2-2) of key (4) moving belt dynamic condenser sensor (1) moves and causes the capacitance variations of capacitive transducer (1), the physical transformation circuit (2) that constitutes based on capacitive transducer (1) is converted to the square wave pulse width variation with the capacitance variations of capacitive transducer (1), and the pulse width that digital drafts testing circuit (3) is measured the square-wave signal of physical transformation circuit (2) obtains the relevant information of piano key rolling reduction.

Fig. 2 is the related capacitor sensor structure figure of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Shown capacitive transducer (1) comprises negative capacitance pole plate (2-11), positive capacitor plate (2-3) and dielectric plate (2-2) composition; Negative capacitance pole plate (2-1) is positioned at the outermost both sides of capacitive transducer (1), and positive capacitor plate (2-3) is positioned between the negative capacitance pole plate (2-1), and dielectric plate (2-2) is positioned between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3); Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) are fixed on the pedestal wiring board (6-1) equidistant parallel discharging; Dielectric plate (2-2) is fixed in key (4) below, equidistant parallel discharging; Dielectric plate after the installation (2-2) is parallel to be interspersed between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3), constitutes dielectric plate (2-2) with respect to negative capacitance pole plate (2-1) and the positive parallel mobile bar structure of capacitor plate (2-3); When key was depressed, dielectric plate (2-2) moved with respect to negative capacitance pole plate (2-1) and positive capacitor plate (2-3), the displaced air dielectric, and the equivalent dielectric coefficient of change capacitive transducer (1) causes the capacitance variations of capacitive transducer (1).

Fig. 3 is related auto-excitation type rectangle wave generation circuit and an oscillogram thereof of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Shown auto-excitation type rectangle wave generation circuit (3-1) comprising: based on the RC circuit and the hysteresis loop comparator of capacitive transducer (1) composition.The RC loop again as feedback network, discharges and recharges the automatic conversion that realizes the output high-low level both as delay link by RC.Because the electric capacity of capacitive transducer (1) is proportional to the cycle of the square-wave signal (3-2) of physical transformation circuit (2) output,, the capacitance variations that piano key rolling reduction brings changes so just being reflected as the cycle of square-wave signal.

Fig. 4 is related separated exciting rectangle wave generation circuit and an oscillogram thereof of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Shown separated exciting rectangle wave generation circuit (4-1) comprising: driving source (4-2), hysteresis loop comparator and the RC circuit of forming based on capacitive transducer (1).Driving source (4-2) provides the square wave pumping signal that the RC circuit discharges and recharges.The RC circuit discharges and recharges and produces the different charging rise time.Because the electric capacity of capacitive transducer (1) is directly proportional with charging rise time (4-3), so the capacitance variations that piano key rolling reduction brings just is reflected as the variation of charging rise time.

Fig. 5 is the related digital drafts testing circuit block diagram of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Shown digital drafts testing circuit (3) realized by the FPGA/CPLD circuit, comprises the drafts digitizing, rubs the string parameter extraction, string characteristic correction, dynamics characteristic correction, pumping signal processing module are extracted, rubbed to dynamics before the key.Numeral drafts testing circuit (3) uses the square wave pulse width of pulsewidth counter measures physical transformation circuit (2) output, utilize square wave pulse width count value to record piano key rolling reduction, drafts is carried out data processing, move with extraction by real-time location and to rub the string parameter, by degree of testing the speed in real time with pick-up key before dynamics, numeral drafts testing circuit (3) is according to parameter setting, by rub the string characteristic correction, dynamics characteristic correction link is proofreaied and correct dynamics before rubbing string parameter, key, measures and rub the requirement of string simulation to reach the key dynamics.When physical transformation circuit (2) adopts separated exciting rectangle wave generation circuit (4-1), numeral drafts testing circuit (3) need discharge and recharge the square wave pumping signal for capacitive transducer (1) provides, and pumping signal will guarantee that capacitive transducer (1) charges normal the threshold value above hysteresis loop comparator.

Fig. 6 is the related wiring layout of capacitive transducer in key of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.The capacitor plate of the capacitive transducer after the assembling (1) is a trapezium structure, makes capacitor plate over against the area maximum under situation about not influencing by key motion.The lower sideline of the dielectric plate after the assembling (2-2) is an arc, guarantees that dielectric plate (2-2) does not influence the motion of button, and make button press the back dielectric plate (2-2) with capacitor plate over against the area maximum.What promote capacitor plate can significantly strengthen the electric capacity of capacitive transducer (1) over against the area of area and dielectric plate, improves the precision of measuring.

Fig. 7 is the related capacitive transducer assembling wiring diagram of variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device.Positive terminal (6-2) links to each other with the positive capacitor plate (2-3) of capacitive transducer (1), and negative terminals (6-3) links to each other with the negative capacitance pole plate (2-1) of capacitive transducer (1).Positive terminal (6-2) and negative terminals (6-3) are laid on the pedestal wiring board (6-1) with the form of PCB circuit.After installing, negative terminals (6-3) want ground connection to guarantee the high anti-jamming capacity of capacitive transducer (1).

Claims (4)

1. variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device, it is characterized in that: device comprises capacitive transducer (1), physical transformation circuit (2) and digital drafts testing circuit (3), capacitive transducer (1) is installed in key (4) below, the dielectric plate (2-2) of key (4) moving belt dynamic condenser sensor (1) moves and causes the capacitance variations of capacitive transducer (1), the physical transformation circuit (2) that constitutes based on capacitive transducer (1) is converted to the square wave pulse width variation with the capacitance variations of capacitive transducer (1), and the pulse width that digital drafts testing circuit (3) is measured the square-wave signal of physical transformation circuit (2) obtains the relevant information of piano key rolling reduction.

2. variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device according to claim 1 is characterized in that: related capacitive transducer (1) is made up of negative capacitance pole plate (2-1), positive capacitor plate (2-3) and dielectric plate (2-2); Negative capacitance pole plate (2-1) is positioned at the outermost both sides of capacitive transducer (1), and positive capacitor plate (2-3) is positioned between the negative capacitance pole plate (2-1), and dielectric plate (2-2) is positioned between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3); Negative capacitance pole plate (2-1) and positive capacitor plate (2-3) are fixed on the pedestal wiring board (6-1) equidistant parallel discharging; Dielectric plate (2-2) is fixed in key (4) below, equidistant parallel discharging; Dielectric plate after the installation (2-2) is parallel to be interspersed between negative capacitance pole plate (2-1) and the positive capacitor plate (2-3), constitutes dielectric plate (2-2) with respect to negative capacitance pole plate (2-1) and the positive parallel mobile bar structure of capacitor plate (2-3); The positive terminal (6-2) of capacitive transducer (1) links to each other with positive capacitor plate (2-3), negative terminals (6-3) links to each other with negative capacitance pole plate (2-1), positive terminal (6-2) and negative terminals (6-3) are laid on the pedestal wiring board (6-1) with the form of PCB circuit, negative terminals (6-3) ground connection of capacitive transducer (1).

3. variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device according to claim 1 is characterized in that: related physical transformation circuit (2) adopts auto-excitation type rectangle wave generation circuit (3-1) or separated exciting rectangle wave generation circuit (4-1); Auto-excitation type rectangle wave generation circuit (3-1) utilizes the square wave oscillation circuit that constitutes based on capacitive transducer (1) capacitance variations of capacitive transducer (1) to be converted to the variation in square wave cycle; Separated exciting rectangle wave generation circuit (4-1) utilizes the threshold voltage comparator circuit that constitutes based on capacitive transducer (1) that the capacitance variations of capacitive transducer (1) is changed the variation of the charging rise time (4-3) of capacitive transducer (1), and the square wave that discharges and recharges of capacitive transducer (1) is provided by digital drafts testing circuit (3) in the separated exciting rectangle wave generation circuit (4-1).

4. variable dielectric capacitor type oscillation measurement of piano key rolling reduction sensing device according to claim 1, it is characterized in that: related digital drafts testing circuit (3) is realized by the FPGA/CPLD circuit, numeral drafts testing circuit (3) is measured piano key rolling reduction by the variation in the square wave cycle of detection physical transformation circuit (2) output, degree of testing the speed, correction in real time measured to realize the keystroke dynamics to piano key rolling reduction, piano key rolling reduction carried out real-time location move, proofread and correct to realize rubbing the string analog functuion.

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