Summary of the invention
The purpose of this invention is to provide the electric capacity that a kind of basis measures and the variation of oscillation frequency and carry out the vector calculation of pressure, calculate stress point and the method for amount of force and the device of realizing this method of dull and stereotyped suffered external force according to the vector force value that calculates.
Technical essential of the present invention is: provide a kind of capacitance variations of utilizing to carry out method for measuring vector pressure, this method is divided into following steps: (1) is provided with drift angle or the apical position that four variable capacitance pressure transducers are distributed in stressed flat board, to obtain the capacitance of diverse location; (2) oscillatory circuit is transformed into the electric signal with certain frequency scope with the capacitance that obtains; (3) respectively the electric signal of each direction on two relative vertical direction is compared, and calculate vector pressure difference value on each direction respectively; (4), draw the stress point and the external force effect size of dull and stereotyped suffered external force according to the vector pressure difference value on described two relative vertical direction.
Further, the described relative vertical direction of step (3) is to be in the X coordinate of the horizontal direction on the same surface level and the Y coordinate of vertical direction.
Further, the described process of step (3) is: measure electric signal earlier, promptly with counter frequency is counted, carry out the vector calculation of pressure again.
Another technical essential of the present invention is: provide a kind of capacitance variations of utilizing to carry out the measuring vector pressure device, this device comprises a stressed flat board, four drift angles or top at described stressed flat board respectively are provided with a variable capacitance pressure transducer, and each variable capacitance pressure transducer connects a circuit unit.
The variable capacitance pressure transducer is arranged on the lower surface of described stressed flat board.
The variable capacitance pressure transducer is made of force column, elastic electrode, pad, dielectric, electrode, separation layer; Force column directly contacts stressed flat board, between elastic electrode and the dielectric pad is set, and two dielectric mirror images arranged side by side are symmetrical arranged, and the centre is separated by separation layer, and the dielectric lower surface is provided with electrode.
Stressed flat board is made by rigid material.
Circuit unit is made up of oscillation circuit unit, amplification and rectification circuit unit, frequency counting unit and vector computing unit and outputting data elements; Oscillation circuit unit becomes an oscillator signal in order to the signal transformation with electric capacity, amplify shaping unit in order to amplify and the shaping oscillator signal, when oscillator signal is enough used, can directly send into the frequency counting unit without amplifying shaping unit, calculate the oscillation frequency of each variable capacitance pressure transducer correspondence by the frequency counting unit, by the vector computing unit oscillation frequency signal is carried out vector again and calculate, at last by outputting data elements output vector difference.
Described oscillation circuit unit is for holding the sense oscillation circuit unit.
Advantage of the present invention and effect are: simple in structure, be convenient to sensing micro force, can fast detecting to the variation of dull and stereotyped pressure and calculate the position of dull and stereotyped stress point, can proofread and correct voluntarily, be fit to be applied to multiple fields such as computer entry device, electronic whiteboard and mobile phone, PDA, multimedia interactive equipment.
Embodiment
Describe below in conjunction with the embodiment of accompanying drawing the application.
Fig. 1 is the upward view of device of the present invention, and it comprises stressed dull and stereotyped 1 and variable capacitance pressure transducer 2.It is less that stressed dull and stereotyped 1 rigid plate preferably, rigid plate are subjected to external force to do the time spent distortion, is convenient to measure and calculates.Variable capacitance pressure transducer 2 is arranged on stressed dull and stereotyped 1 ad-hoc location, embodiment of the present invention is arranged on four also relative vertical distribution of drift angle or top of stressed dull and stereotyped cuboid, in order to measure stressed dull and stereotyped 1 pressure information that is born and to export corresponding signal.
Described variable capacitance pressure transducer 2 is made of force column 21, elastic electrode 22, pad 23, dielectric 24, electrode 25 and separation layer 26.Force column 21 directly contacts stressed dull and stereotyped 1, in order to transmit stressed dull and stereotyped 1 suffered pressure; Between elastic electrode 22 and the dielectric 24 pad 23 is set, plays buffer action; Two dielectric 24 mirror image symmetries arranged side by side are placed, and the centre is separated by separation layer 26; Dielectric 24 lower surfaces are provided with electrode 25, draw lead or conductor from electrode 25, in order to transmit detected electric signal to circuit unit.
According to the ultimate principle of electric capacity as can be known, from a dielectric, draw two electrodes, there is a capacitance in the capital, dielectric specific inductive capacity, distance and area between the size of capacitance and two electrodes have direct relation, change wherein arbitrary condition, just can reach the purpose and the effect that change electric capacity.Described variable capacitance pressure transducer 2 promptly is based on this principle work.
Fig. 5 is the not synoptic diagram of stress of variable capacitance pressure transducer 2, and Fig. 6 is the synoptic diagram of variable capacitance pressure transducer 2 stresses.When stressed dull and stereotyped 1 was in plumbness, elastic electrode 22 is gravitate only, stressed dull and stereotyped 1 and force column 21 under the elastic force effect of elastic electrode 22, be in original state, promptly and between the dielectric 24 do not have acting force, as shown in Figure 5; Stressed dull and stereotyped 1 is in heeling condition, horizontality and be subjected to external force and do the time spent, the capital produces deformation, contact area between elastic electrode 22 and the dielectric 24 will change at this moment, as shown in Figure 6, when stressed dull and stereotyped 1 pressure changes, under the effect of force column 21, contact area between elastic electrode 22 and the dielectric 24 is also changing, and stressed dull and stereotyped 1 pressure is big more, contact area between elastic electrode 22 and the dielectric 24 is also just big more, effective dielectric between elastic electrode 22 and dielectric 24 is just many more, and corresponding capacitance is also just big more.
Circuit unit block diagram of the present invention as shown in Figure 3, it comprises oscillation circuit unit, amplification and rectification circuit unit, frequency counting unit, vector computing unit and outputting data elements, each unit can be made up of the circuit component that separates, also can form by integrated circuit, as frequency counting unit in actual applications often is exactly to utilize the counter that carries in the single-chip microcomputer, counter can be set separately, the vector computing unit is exactly a processor, and outputting data elements is exactly the output interface of single-chip microcomputer.
Fig. 4 is the process flow diagram of the method for the invention.As shown in Figure 4, step (1) at first is the capacitance that is obtained variation by variable capacitance pressure transducer 2; Step (2) obtains the correspondent frequency signal by an oscillatory circuit then; Step (3) is then carried out vector to frequency signal and is calculated and draw difference; Step (4), the last information that is worth stress point according to phasor difference.
In step (1), stressed dull and stereotyped 1 virgin state has three kinds, is respectively plumbness, horizontality, heeling condition, and three kinds of different virgin states are to there being three different initial values.And the size of the capacitance that obtains by variable capacitance pressure transducer 2, the influence of not stressed dull and stereotyped 1 virgin state of living in.Concrete reason is analyzed as follows:
First kind of state is stressed dull and stereotyped 1 to be in plumbness.At this moment, the elastic electrode 22 of variable capacitance pressure transducer 2 does not contact with dielectric 24, and the capacitance at electrode 25 two ends is an initial value, and this initial value is a null value.When stressed dull and stereotyped 1 is subjected to an external force F, as shown in Figure 2, stressed dull and stereotyped 1 passes to the variable capacitance pressure transducer 2 at four angles with suffered external force, the application point difference of external force, the variation of four variable capacitance pressure transducers 2 also is inconsistent, outer point of force application distance variable capacitive pressure transducer 2 is near more, the variation of this variable capacitance pressure transducer 2 is big more, institute causes that changes in capacitance is big more, otherwise, outer point of force application distance variable capacitive pressure transducer 2 is far away more, and institute causes that changes in capacitance is more little.
Second kind of state is stressed dull and stereotyped 1 to be in horizontality.At this moment, because stressed dull and stereotyped 1 deadweight can make variable capacitance pressure transducer 2 produce distortion, promptly electric capacity has a non-vanishing initial value.But, the variable capacitance pressure transducer 2 suffered external force at four angles are consistent on stressed dull and stereotyped 1, the distortion that four variable capacitance pressure transducers 2 produce is consistent, so the vector difference between four capacitive pressure transducers 2 also is the same, promptly difference is zero.When stressed dull and stereotyped 1 is subjected to external force F, the relation of the vector difference between four variable capacitance pressure transducers 2 still is relevant with the size and the position of suffered external force, so stressed dull and stereotyped 1 when being in horizontality, the same situation that can actual response goes out stressed dull and stereotyped 1 suffered external force of device of the present invention.
The third state is stressed dull and stereotyped 1 to be in heeling condition, and promptly stressed dull and stereotyped 1 has certain inclination angle.At this moment, owing to making variable capacitance pressure transducer 2, stressed dull and stereotyped 1 self weight produces certain deformation, and the size that four variable capacitance pressure transducers 2 change all is consistent, so the vector difference between four variable capacitance pressure transducers 2 is zero too.When stressed dull and stereotyped 1 is subjected to external force F, vector difference between four variable capacitance pressure transducers 2, still be relevant with the size and the position of suffered external force, so stressed dull and stereotyped 1 when being in heeling condition, the same situation that can actual response goes out stressed dull and stereotyped 1 suffered external force of device of the present invention.
Each above-mentioned state can carry out repeatedly, can obtain one group of capacitance by variable capacitance pressure transducer 2, and this group capacitance is that variation with pressure changes.
In step (2), one group of capacitance by above-mentioned acquisition obtains a class frequency signal by corresponding oscillatory circuit respectively.Described oscillatory circuit can be one and hold the sense oscillatory circuit, or appearance resistance oscillatory circuit and other similar circuit, promptly can have influence on the frequency of oscillatory circuit or other electrical quantity by the variable capacitance that obtains.Present embodiment adopts to such an extent that be to hold the sense oscillatory circuit.Like this, four 2 pairs of variable capacitance pressure transducers should have four oscillatory circuits, can obtain four oscillation frequency.
In step (3), four oscillation frequency signals are carried out vector calculate and draw difference.The vector calculation process is as follows: aforementioned four oscillation frequency signals, a variable capacitance pressure transducer 2 on respectively corresponding stressed dull and stereotyped 1 four drift angles, promptly on stressed dull and stereotyped 1 vertical relatively X-axis and Y direction, X-direction is to there being two variable capacitance pressure transducers 2, Y direction is to there being two variable capacitance pressure transducers 2, to the advanced line frequency counting of two frequency signals of X-direction, be sent to the vector computing unit again and carry out vector calculating, draw the vector difference of X-direction, two frequency signals to Y direction adopt identical method, advanced line frequency counting, be sent to the vector computing unit again and carry out vector calculating, draw the vector difference of Y direction.Its concrete calculating principle is as follows:
Vertical relatively X-axis and Y-axis constitute a plane right-angle coordinate, and four variable capacitance pressure transducer locas are four point of fixity x on this plane right-angle coordinate
1, x
2, y
1, y
2, x wherein
1, x
2At x axle horizontal ordinate direction, y
1, y
2In y axle ordinate direction.
When external force F acts on dull and stereotyped going up, promptly be to act on the plane that constitutes by X-axis and Y-axis, external force F is F (x) at the component of X-direction, is F (y) at the component of Y direction, according to resolution of force principle, x
1, x
2, y
1, y
2So the corresponding external force F of meeting component in different directions is at x
1, x
2Component on the point is F (x
1) and F (x
2), at y
1, y
2Component on the point is F (y
1) and F (y
2).
According to x
1, x
2Between relation can obtain relative position on the corresponding x axle of external force F, the computing formula of its relative position is: F (x)=F (x
i)/(F (x
1)+F (x
2)), same, according to y
1, y
2Between relation just can obtain the relative position of external force F correspondence on the y axle, the computing formula of its relative position is: F (y)=F (y
i)/(F (y
1)+F (y
2)), in view of the above, just can draw that external force F acts on size on the stressed flat board and application point is (F (x), F (y)).
In step (4), be worth the information of stress point according to phasor difference.By the X-axis of above acquisition and the vector difference of Y direction, and the initial value when virgin state, just can obtain the position and the size of outer point of force application on stressed dull and stereotyped 1, and export by outputting data elements.
In addition, when stressed dull and stereotyped 1 is in non-perpendicular state, owing to making variable capacitance pressure transducer 2, self weight produces certain deformation, according to the analysis of being done in the abovementioned steps (1), vector difference between four variable capacitance pressure transducers 2 is similarly zero, so, can at processor or the application terminal be provided with an initialization or zero clearing program, said apparatus is proofreaied and correct voluntarily.
The present invention is simple in structure, and is highly sensitive, has very excellent application value, is fit to be applied to multiple applications such as computer entry device, electronic whiteboard and mobile phone, PDA, multimedia interactive equipment.