CN105005775A - Handwritten multidimensional force information acquisition device - Google Patents

Abstract

The invention relates to a handwritten multidimensional force information acquisition device. An acquisition system comprises a data acquisition module and a sensing system signal processor. The data acquisition module comprises a sensor matrix. The sensor matrix is arranged below a writing area. A sensor comprises an X direction capacitor unit group and a Y direction capacitor unit group. The X direction capacitor unit group and the Y direction capacitor unit group comprise capacitor unit modules. Each capacitor unit module is in a comb-like structure composed of more than two strip capacitor units. According to the electronic signature multidimensional force information acquisition system provided by the invention, three-dimensional space multidimensional force vector information generated in a writing process can be acquired; the multidimensional force information hidden behind characters cannot be seen by other people and is inimitable; and an identity authentication feature based on the acquired three-dimensional space multidimensional force information is remarkably beneficial.

Description

Hand-written multi-dimensional force information collecting device

Technical field

The invention belongs to identity identifying technology field, relate to electronic signature, be specifically related to a kind of hand-written multi-dimensional force information collecting device.

Background technology

Biological identification technology refers to that the physical trait that foundation people is exclusive or behavioural habits carry out unique authentication to individuality.As an emerging science, biological identification technology has been deep into the every aspect of social life, brings safety assurance to the public, becomes generally acknowledged identity recognizing technology.Feature used by bio-identification has uniqueness usually; can quantitative measurment; the features such as persistence; also to be convenient to gather simultaneously; user is acceptant; the method for anti-counterfeit that the mechanisms such as sample is not easily forged, bank commonly use now the most gathers signature and fingerprint, and we consume places by also having password and the two-layer protection that signs electronically during the modes of payments such as bank card, credit card at some.But signature is a kind of static nature, have the advantages that to forge, be used in the fields such as Unionpay's electronic signature as a kind of static nature and also there is certain potential safety hazard.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides a kind of hand-written multi-dimensional force information collecting device, the signature of user can not only be collected, and be captured in three dimensions (O-XYZ coordinate system) the multi-dimensional force Vector Message produced in writing process, this " hiding " is in Chinese character multi-dimensional force information behind, that others cannot see, thus also cannot imitate, and hand-written behavior is a kind of active behavior, be different from palmmprint, the static behaviors such as iris, therefore, as authentication feature, there is outstanding beneficial effect based on the three dimensions multi-dimensional force information obtained.

Technical scheme of the present invention is: a kind of hand-written multi-dimensional force information collecting device, described acquisition system comprises data acquisition module and sensor-based system signal processor, data acquisition module comprises sensor matrices, sensor matrices is arranged on to be write below region, described sensor comprises X-direction capacitor cell group and Y-direction capacitor cell group, described X-direction capacitor cell group and Y-direction capacitor cell group include capacitor cell module, the comb teeth-shaped structure that described capacitor cell module is made up of plural strip capacitor cell, each strip capacitor cell comprises the drive electrode of top crown and the induction electrode of bottom crown, described capacitor cell module comprises by two or more width a ₀length b ₀strip capacitor cell composition the first strip capacitor cell group and two or more width ka ₀length b ₀strip capacitor cell composition the second strip capacitor cell group.

Hand-written multi-dimensional force information collecting device, described harvester also comprises display module and sensitive diaphragm, described display module connects sensor-based system signal processor, and sensitive diaphragm covers sensor array surface, the length of described display module with wide compared to sensor array with identical scale smaller.The drive electrode of described each strip capacitor cell is identical with induction electrode width, and the length of drive electrode is greater than induction electrode length, and drive electrode length two ends are reserved left poor position δ respectively _leftwith right poor position δ _right, b _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein, b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell.Described poor position δ _left=δ _right, and wherein d ₀for strip capacitor cell dielectric thickness, G is the modulus of rigidity of elastic medium, σ _maxfor maximum stress value.The lead-in wire that described comb teeth-shaped structure comprises more than 20 strip capacitor cells, connects one to one with strip capacitor cell, is provided with electrode separation a between adjacent two strip capacitor cells _δ.Described parallel-plate area S=M (a ₀+ 2a _δ+ ka ₀) b ₀/ 2, wherein, M is strip capacitor cell quantity, b ₀for the length of strip capacitor cell, a ₀the width of strip capacitor cell.The strip capacitor cell lead-in wire of described first strip capacitor cell group and the second strip capacitor cell group is by parallel connection or be independently connected to sensor-based system signal processor.The width of described strip capacitor cell wherein, d ₀for dielectric thickness, E is the Young modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described first strip capacitor cell group and be respectively equipped with intermediate translator between the second strip capacitor cell group and sensor-based system signal processor, intermediate translator is for arranging voltage to electric capacity or frequency to the transmission coefficient of electric capacity.

The present invention has following good effect: electronic signature multi-dimensional force information acquisition system of the present invention gathers three dimensions (O-XYZ coordinate system) the multi-dimensional force Vector Message produced in writing process, this " hiding " is in Chinese character multi-dimensional force information behind, that others cannot see, thus also cannot imitate, and hand-written behavior is a kind of active behavior, react individual custom feature.In addition, information display module and acquisition module are separated by the present invention, avoid deliberately model, reduce imitability, improve factor of safety.Capacitive pressure transducer of the present invention effectively uses platen area, and effectively solved between three-dimensional force by modes such as drive electrode two ends are reserved and be coupled, and utilize special strip capacitance structure, make normal direction and tangential conversion all reach higher linear, precision and sensitivity.

Accompanying drawing explanation

Fig. 1 is strip capacitor cell and the coordinate system thereof of the specific embodiment of the present invention.

Fig. 2 is the strip capacitor cell schematic diagram of the specific embodiment of the present invention.

Fig. 3 is the strip capacitor cell dextrad skew schematic diagram of the specific embodiment of the present invention.

Fig. 4 is the strip capacitor cell left-hand skew schematic diagram of the specific embodiment of the present invention.

Fig. 5 is the width of the specific embodiment of the present invention is a ₀and ka ₀electric capacity to stressed deflection graph.

Fig. 6 is the parallel-plate three-dimensional force pressure sensor structure figure of the specific embodiment of the present invention.

Fig. 7 is the signal schematic representation that the cell capacitance of the specific embodiment of the present invention is right.

Fig. 8 is the hand-written multi-dimensional force information collecting device structural drawing of the specific embodiment of the invention.

Fig. 9 is specific embodiment of the invention handwriting area structural drawing.

Figure 10 is specific embodiment of the invention three-dimensional force principal character component curve figure.

Wherein, 1 display module, 2 handwriting areas, 201 sensitive diaphragms, 202 sensor arraies.

Embodiment

Contrast accompanying drawing below, by the description to embodiment, the specific embodiment of the present invention is as the effect of the mutual alignment between the shape of involved each component, structure, each several part and annexation, each several part and principle of work, manufacturing process and operation using method etc., be described in further detail, have more complete, accurate and deep understanding to help those skilled in the art to inventive concept of the present invention, technical scheme.

Main thought of the present invention is: now common identity identifying method comprises signature and some biological characteristic discriminating conducts, such as fingerprint and iris etc., but fingerprint and iris relate to individual privacy, signature has forgeability, and therefore the present invention adopts multi-dimensional force information behind of writing as a kind of secondary identities recognition methods.Writing movements is accustomed to, and is characteristic a kind of feature that people are formed in long-term writing process.Same user is in the process of writing identical Chinese character, the curve of its acting force presents the repeatability of certain degree, therefore, the knowledge of biomechanics aspect is used to carry out mechanical analysis to the data of Chinese-character writing process measurement, find out three-dimensional force feature that different writers embodies in writing process and the relation that Chinese character is formed, as the signature identification of writing.

Electronic signature multi-dimensional force information acquisition system of the present invention comprises data acquisition module, display module and sensor-based system signal processor, the core of data acquisition module is three-dimensional force sensor, nib in three-dimensional force sensor collection writing process and the three-dimensional force information between board, three-dimensional force sensor is arranged on to be write below region, gather the acting force information in writing process, the weak signal that sensor exports is by amplifying, send in processor after filtering and analog-to-digital conversion, processor realizes the process etc. to data, and the trace information that power acquisition module obtains is transferred to display module carries out visual feedback.Handwriting input module in the present invention is separated with display module, can reflect the writing style of a people more really, be reduced by the possibility of model, improves the security of authentication.

As shown in Figure 8, for the hand-written force acquisition device of the present invention, wherein 1 is display module, 2 for writing region, as Fig. 2, write region and comprise sensitive diaphragm 201 and sensor array 202, sensitive diaphragm is the film that one deck is very thin, cover the surface of sensor array, sensor array is classified as rectangular array, its length all becomes identical ratio with viewing area with wide, also namely the length of viewing area becomes identical scale smaller with wide compared to sensor array, a region one_to_one corresponding of each sensor and display module, in the mapping signature process of reality, the display of the viewing area corresponding to the sensor writing of the power of writing detected, complete figure display and interactive function, user can see the result of hand-written motion intuitively.

After by oscillator electric capacity being converted into frequency, add limiting amplifier, because oscillator exports two variable quantities and frequency and amplitude, in order to limit the change of amplitude, and make amplitude become definite value, thus the change of output quantity is made to only have frequency, using it as judging measured size.Add frequency discriminator after limiter, be used for compensating the non-linear of remainder, make whole system linearization, and frequency signal is converted to the analog output such as voltage or electric current to amplifier, finally carry out amplification again and export.

As the electrode plate structure figure that Fig. 4-6 is pressure transducer of the present invention, sensor comprises X-direction capacitor cell group and Y-direction capacitor cell group, described X-direction capacitor cell group and Y-direction capacitor cell group include capacitor cell module, described capacitor cell module adopts the comb teeth-shaped structure be made up of plural strip capacitor cell, and each strip capacitor cell comprises the drive electrode of top crown and the induction electrode of bottom crown.Described capacitor cell module comprises by two or more width a ₀length b ₀first strip capacitor cell group of strip capacitor cell composition and two or more width ka ₀length b ₀second strip capacitor cell group of strip capacitor cell composition.The drive electrode of described each strip capacitor cell is identical with induction electrode width, and the length of drive electrode is greater than induction electrode length, and drive electrode length two ends are reserved left poor position δ respectively _leftwith right poor position δ _right, δ _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein, b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell.Described poor position δ _left=δ _right, and wherein d ₀for dielectric thickness, G is the modulus of rigidity of elastic medium, τ _maxfor maximum stress value.The lead-in wire that described comb teeth-shaped structure comprises more than 20 strip capacitor cells, connects one to one with strip capacitor cell, is provided with electrode separation a between adjacent two strip capacitor cells _δ.Described parallel-plate area S=M (a ₀+ 2a _δ+ ka ₀) b ₀/ 2, wherein, M is strip capacitor cell quantity, b ₀for the length of strip capacitor cell, a ₀the width of strip capacitor cell.The strip capacitor cell lead-in wire of described first strip capacitor cell group and the second strip capacitor cell group is by parallel connection or be independently connected to sensor-based system signal processor.The width of described strip capacitor cell wherein, d ₀for dielectric thickness, E is the Young modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described first strip capacitor cell group and be provided with intermediate translator between the second strip capacitor cell group and sensor-based system signal processor, intermediate translator is for arranging voltage to electric capacity or frequency to the transmission coefficient of electric capacity.

1, the conversion characteristic of strip capacitor cell

(1) pumping signal and coordinate system

Strip capacitor cell is placed in the rectangular coordinate system shown in Fig. 1, pole plate plane length b ₀, width a ₀, dielectric thickness d ₀.Three-dimensional simulation puts on the outside surface of capacitor plate, and the contact acting force of generation has Fx, Fy and Fz tri-durection components, and the action direction of Fx and Fy is along X-axis and Y-axis, and the action direction of Fz along OZ axle namely direction, normal direction and tangential stress are a kind of stress tensor, can output capacitance respond between the lead-in wire of electrode; Normal stress σ ₀=Fn/A, wherein A=a ₀b ₀for pole plate normal direction stress surface, Fn=Fz is normal component; Both side surface produces paired tangential stress τ _x=Fx/A, τ _y=Fy/A.

According to the Hooke's law in Elasticity, σ _nand τ _x, τ _yelastic body all will be made to produce corresponding distortion.Wherein,

${\mathrm{\σ}}_n=E\·{\mathrm{\ϵ}}_n=E\·{\mathrm{\δ}}_n/d_0=\frac{F_n}{A}---\left(1\right)$

$\±{\mathrm{\τ}}_x=\±{\mathrm{\γ}}_x\·G=\±G\·{\mathrm{\δ}}_x/d_0=\±\frac{F_x}{A}---\left(2\right)$

$\±{\mathrm{\τ}}_y=\±{\mathrm{\γ}}_y\·G=\±G\·{\mathrm{\δ}}_y/d_0=\±\frac{F_y}{A}---\left(3\right)$

In formula, E is the Young modulus (unit: GN/m of elastic medium ²), G is the modulus of rigidity (unit: GN/m of elastic medium ²), δ n is the Normal Displacement (unit: μm) of elastic medium, and δ x and δ y is the relative dislocation (unit: μm) of the upper and lower two-plate of capacitor, and its sign is pointed to by coordinate axis and determined.

(2) capacitance equation and input-output characteristic thereof

The initial capacitance of rectangular parallel plate capacitor is:

$C_0=\frac{{\mathrm{\ϵ}}_0.{\mathrm{\ϵ}}_r\·a_0\·b_0}{d_0}---\left(4\right)$

In formula, ε ₀vacuum medium electric constant is 8.85PF/m, ε _r=2.5 is dielectric relative dielectric constant.D ₀by σ _nexcitation produce relative deformation ε _n=δ _n/ d ₀=σ _n/ E, substitutes into (4) and obtains input-output characteristic

$C_n={\mathrm{\ϵ}}_0.{\mathrm{\ϵ}}_r\frac{a_0\·b_0}{d_0(1-{\mathrm{\ϵ}}_n)}={\mathrm{\ϵ}}_0\·{\mathrm{\ϵ}}_r\frac{a_0\·b_0}{d_0(1-\frac{F_n}{AE})}---\left(5\right)$

(3) linearity under normal stress effect and sensitivity

A, the normal direction linearity

F in (5) formula _nin the denominator, therefore C _n=f (F _n) relation be nonlinear, because of conversion range in maximal value σ _nmaxcompared with dielectric resilient constant E, ε _na very little amount, i.e. ε in denominator _n<<1, (5) are omitted the higher-order shear deformation of more than quadratic power by series expansion, and (5) formula can be reduced to:

$C_n=C_0(1+\mathrm{\&epsiv;})=C_0(1+\frac{F_n}{A\&CenterDot;E})---\left(6\right)$

Visible at C _nwith F _nconversion characteristic in the maximum relative error of the normal direction linearity close to zero.

B, sensitivity

By the definition of normal direction sensitivity

Can linear sensitivity be obtained by (6) formula,

$S_{n1}=C_0/AE={\mathrm{\&epsiv;}}_0{\mathrm{\&epsiv;}}_r/d_{0}E---\left(7\right)$

By (5) formula then

$S_{n2}=\frac{{\mathrm{dC}}_n}{{\mathrm{dF}}_n}=C_0\&CenterDot;\frac{1}{1-2\mathrm{\&epsiv;}}=C_0\&CenterDot;\frac{1}{1-2\frac{F_n}{A\&CenterDot;E}}---\left(8\right)$

S _n2with F _nand become, F _nlarger, S _n2larger, in mild nonlinear in whole conversion characteristic.

(4) tangential stress τ _xand τ _ycapacitance variations under excitation

Tangential stress τ _xand τ _ydo not change the physical dimension parameter b of pole plate ₀and a ₀, to dielectric thickness d ₀also do not have an impact.But τ _xand τ _ychange the space structure of strip capacitor cell, between the upper bottom crown faced by forward, there occurs dislocation skew.Now for OX direction, pole plate is at τ _xdislocation skew δ under effect _x.

Work as τ in fig. 2 _xwhen being zero, a _{on 0}=a _{0 time}just right, free area A between substrate _τ=a ₀b ₀; In figure 3, at τ _xunder the effect of dextrad, top crown creates dislocation skew δ to the right relative to bottom crown _x, thus make the useful area A between bottom crown when calculating electric capacity _τ=(a ₀-δ _x) b ₀; In Fig. 4, work as τ _xduring for left-hand, dislocation skew δ _xthen left, A _τ=(a ₀-δ _x) b ₀, τ _xwhen left-hand and dextrad, the reduction of useful area is identical, and consequent electric capacity is:

$C_{{}_{\mathrm{\&tau;}x}}=\frac{{\mathrm{\&epsiv;}}_0.{\mathrm{\&epsiv;}}_r\&CenterDot;(a_0-{\mathrm{\&delta;}}_x)\&CenterDot;b_0}{d_0}---\left(9\right)$

According to shearing Hooke's law

${\mathrm{\&tau;}}_x={\mathrm{\&gamma;}}_x\&CenterDot;G=G\&CenterDot;{\mathrm{\&delta;}}_x/d_0---\left(10\right)$

(10) are substituted into (9) can obtain

$C_{{}_{\mathrm{\&tau;}x}}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;{\mathrm{\&delta;}}_x\&CenterDot;b_0}{d_0}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0\mathrm{\&tau;}x}{G}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r{F}_x}{{\mathrm{Ga}}_0}---\left(11\right)$

(11) formula is the input-output characteristics under shearing stress, C _τwith τ _xlinear.

And its sensitivity

$S_{{}_{\mathrm{\&tau;}x}}=\frac{{\mathrm{dC}}_{{}_{\mathrm{\&tau;}x}}}{{\mathrm{dF}}_x}=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{{\mathrm{Ga}}_0}---\left(12\right)$

The similar analysis in formula (9)-(12) is suitable for and τ equally _ywith C _{τ y}characteristic and technical indicator, the only long limit b of strip capacitor cell in formula ₀oX direction of principal axis should be arranged at, and its minor face a ₀then in OY direction.

2, contact parallel plate capacitor design

(1) planar design of parallel plate capacitor

The original index normal direction Max.contact stress σ of setting _nmaxfor 200Kpa, if the stressed A of normal direction is square 10 × 10mm ², then maximum normal force F _zmaxfor σ _nmaxa=20N.Tangential Max.contact stress τ _maxfor 70Kp, the distribution of force face of tangential stress is 10 × 10mm ², then maximum tangential force component F _xmax=F _ymax=τ _maxa=7N.

Strip capacitor cell constructive variations shown in Fig. 3 and Fig. 4, only illustrates that electric capacity exports and tangential stress ± τ _xthe relation of input, capacitance increase is all negative, and therefore this initial capacitance structure is not suitable for as right ± τ _xobtain the response increasing and decreasing electric capacity.The present invention adjusts the initial configuration of bottom crown on strip capacitor cell for this reason, and width is a ₀and ka ₀strip capacitor cell form a pair capacitor cell to (C _lwith C _r), specifically as shown in Figure 5.

In Fig. 5, capacitor cell C _land C _relectrode size b ₀, d ₀all identical, width one is a ₀, one is ka ₀, wherein k is constant, is preferably greater than the integer of 1.Work as τ _xwhen=0, C _l=C ₀, C _r=kC ₀, on this basis as at F _xδ is produced under excitation _xmistake skew, offset effect as shown in figure 3 or 4 will be formed.

$C_L=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0\&CenterDot;(a_0-{\mathrm{\&delta;}}_x)}{d_0}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0{\mathrm{\&tau;}}_x}{G}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r{F}_x}{{\mathrm{Ga}}_0}---\left(13\right)$

$C_R=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0\&CenterDot;({\mathrm{Ka}}_0-{\mathrm{\&delta;}}_x)}{d_0}={\mathrm{kC}}_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0{\mathrm{\&tau;}}_x}{G}={\mathrm{kC}}_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r{F}_x}{{\mathrm{Ga}}_0}---\left(14\right)$

C _land C _rcapacitor cell is at same τ _xδ will be produced _xwith Δ C _τresponse.

Thus, formula (11) can be revised as

$C_{{}_{\mathrm{\&tau;}x}}=C_{\mathrm{\&tau;}0}-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{{\mathrm{Ga}}_0}{F}_x$

In formula, for initial capacitance when shearing stress is zero, above formula is shearing stress input-output characteristic, C _{τ x}with F _xlinear relationship, and its sensitivity

Electrode plane see Fig. 6 is arranged, at a 10 × 10mm ²substrate center do cross separate, form four quadrants, upper right first quartile I, upper left second quadrant II, lower-left third quadrant III, bottom right fourth quadrant IV, wherein I, III quadrant is to τ _xmake the capacitor cell combination of response, and II, IV quadrant is to τ _ymake the capacitor cell combination of response.Object-line is 10 × 10mm ²pcb board four edge lines, hachure part represents the outer mode cross section of wax-loss casting process.Using the position of induction electrode in lower floor's PCB substrate as reference, then the layout of drive electrode in the PCB substrate of upper strata should with PCB substrate edge line for benchmark.In figure, four dashed rectangle are the benchmark of induction electrode on bottom crown, put they and geometry datum line differential apart from being δ ₀(0.1mm).

Capacitor cell module adopts comb structure, and capacitor cell module adopts the comb teeth-shaped structure be made up of plural strip capacitor cell, and each strip capacitor cell comprises the drive electrode of top crown and the induction electrode of bottom crown.By formula (12) a ₀less, the sensitivity of tangential stress response is larger, therefore single capacitor cell is strip.If every root strip capacitor cell is wide is a ₀, the groove width between two strip electric capacity is a _δ, then the pitch of every root strip capacitor cell is ka ₀+ a ₀+ 2a _δ.In order to make full use of the plane space of square substrate, M (ka ₀+ a ₀+ 2a _δ) b ₀/ 2 ≈ 1 square substrate surface areas, M is strip electric capacity quantity, then have M (ka ₀+ a ₀+ 2a _δ)=20mm, in formula, groove width a _δunsuitable excessive, otherwise be unfavorable for using the effective plane space on substrate, also unsuitable too small, the constraint of wax-loss casting process is subject to.For making normal direction sensitivity S _nwith tangential sensitivity S _τequal, by formula (7) and (12), make a ₀g=d ₀e, works as d ₀when=0.1mm, k=1.5, thus M can be obtained.

In order to realize τ _xand τ _ybetween tangential response mutually do not have an impact, the drive electrode length two ends reserved difference position δ of strip capacitor cell ₀, therefore b _{0 drives}=b _{0 end}+ 2 δ ₀, wherein at b _{0 drives}two ends length reserved difference potential theory should ensure ${\mathrm{\&delta;}}_0\&GreaterEqual;d_0\&CenterDot;\frac{{\mathrm{\&tau;}}_{\max }}{G},$ Its calculated value is ${10}^{-5}\&times;\frac{70\&times;{10}^3}{2.4\&times;{10}^6}=2.9\&times;{10}^{-8}m={10}^{-2}um<<1um,$ Therefore should b be ensured in technique _{0 drives}-b _{0 end}>=0.01mm.

In order to realize τ _xand τ _ydo not produce any impact to the response of normal direction electric capacity, width is a ₀and ka ₀strip capacitor cell form a pair capacitor cell to (C _lwith C _r) carry out publicity reckoning elimination impact each other.Ensure τ _xproduce τ at I, III quadrant capacitor cell _xelectric capacity response, then produce τ at II, IV quadrant capacitor cell _yelectric capacity response, to ensure that capacitor cell in four quadrants is at τ _xand τ _ytwo groups of differential capacitors pair can be produced under tangential excitation.

(2) calculating of normal stress and tangential force

If width is a in Fig. 6 ₀strip capacitor cell be subject to tangential force τ _x, produce a tangential displacement d _xafter output capacitance value be C ₁, width is ka ₀strip capacitor cell be subject to tangential force τ _x, produce a tangential displacement d _xafter output capacitance value be C ₂, then have:

$C_1=\frac{\mathrm{\&epsiv;}(a_0-d_x)b_0}{d_n}=\frac{{\mathrm{\&epsiv;a}}_0{b}_0}{d_n}-\frac{{\mathrm{\&epsiv;b}}_0{d}_x}{d_n}---\left(15\right)$

$C_2=\frac{\mathrm{\&epsiv;}({\mathrm{ka}}_0-d_x)b_0}{d_n}=\frac{{\mathrm{\&epsiv;ka}}_0{b}_0}{d_n}-\frac{{\mathrm{\&epsiv;b}}_0{d}_x}{d_n}---\left(16\right)$

Obtained by (15)-(16):

$C_1-C_2=\frac{{\mathrm{\&epsiv;a}}_0{b}_0}{d_n}-\frac{{\mathrm{\&epsiv;ka}}_0{b}_0}{d_n}$ Calculate:

$d_n=\frac{{\mathrm{\&epsiv;a}}_0{b}_0(1-k)}{C_1-C_2}---\left(17\right)$

Obtained by (15) * k-(16):

${\mathrm{kC}}_1-C_2=\frac{{\mathrm{\&epsiv;d}}_x{b}_0}{d_n}-\frac{{\mathrm{\&epsiv;kd}}_x{b}_0}{d_n}=\frac{{\mathrm{\&epsiv;d}}_x{b}_0(1-k)}{d_n},$ (17) are substituted into above formula, can obtain:

$d_x=\frac{a_0({\mathrm{kC}}_1-C_2)}{C_1-C_2}---\left(18\right)$

According to $d_n=d_0-\mathrm{\&Delta;}d=d_0(1-\frac{F_n}{E\&CenterDot;S_0})$

Known: $F_n=\frac{(d_n-d_0)E\&CenterDot;S_0}{d_0}$

By $\frac{d_x}{d_0}=\mathrm{\&gamma;}=\frac{\mathrm{\&tau;}}{G}=\frac{F_{\mathrm{\&tau;}}}{G\&CenterDot;S_0},$ So $F_{\mathrm{\&tau;}x}=\frac{{\mathrm{GS}}_0{d}_x}{d_0}.$

In above formula, no matter be normal direction excitation F _nor tangentially encourage F _yall not to O _τhave an impact.Namely automatically σ is eliminated _nand τ _yto τ _xthe coupling of total output or interference comprise at signal because every in the computing of subtracting each other, equivalent and the capacitance variations with symbol are eliminated all automatically.And F _yand F _xto σ _ninterference by upper electrode at b ₀direction increases geometrical length 2 δ ₀eliminate.In like manner F can be obtained _{τ y}.

(4) main material selection and characterisitic parameter thereof

The polar plate spacing d of comb teeth-shaped plane-parallel capacitor ₀=0.1mm, upper and lower base plate inner space, except copper foil electrode, is PDMS (dimethyl silicone polymer) the superlastic insulating medium with lost wax process filling.Its machinery and physical characteristics parameter are Young modulus E=6.2MPa, and its shear modulus is G=4.1MPa, relative DIELECTRIC CONSTANT ε during dielectric polorization _γ=2.5.Because E and G of medium is much smaller than the elastic modulus E of copper _copper=103GPa.Therefore the distortion of capacitor internal medium under stress state is much larger than the distortion of pole plate.

(5) contact conductor design

Be that drive electrode or induction electrode all need to have extension line, consider that each drive electrode is all ground connection in signal level, therefore four groups of drive electrodes only need share same extension line.The induction electrode of four the first strip capacitor cell groups and the second strip capacitor cell group then needs with respective independently extension line, and draw from the side of planar package so whole capacitance component has at least 5 pins, four induction electrodes refer to that X-direction width is a ₀induction electrode and width be ka ₀induction electrode, and Y-direction width is a ₀induction electrode and width be ka ₀induction electrode so that whole assembly top and bottom outside surface can contact with measuring object easily.The present invention, under the support of new material and new technology, completes the design of a kind of novel three-dimensional power sensitization capacitance combination, at 10 × 10mm ²stress surface on, be no matter normal direction or tangential, all can transmit stress more uniformly to medium.In literary composition, four cell capacitance are two to combination distribution.In the contact of non-coplanar force and sensor surface, external force only has 1, and electric capacity response but has 4, and whole battery lead plate, all to asking Fn to contribute, simultaneously by two pairs of capacitor combinations composition systems, can obtain F again _xand F _yinformation, thus complete description three-dimensional force.

Feature extraction is carried out by the force information collected handwriting input device, Figure 10 be a user actual writing Chinese characters " in " principal character component curve after the three-dimensional force information decomposition that collects in process, we by Chinese character " in " carry out Stroke decomposition, as shown in (a) in Figure 10 to (d), 3 width curve maps are expressed as F from top to bottom successively _x, F _y, F _zforce curve.As can be seen from Fig., stroke (a) can cause Y-direction to increase, stroke (b) can first cause X to increase, Y is then caused to increase, stroke (c) can cause X to increase, the same stroke (a) of stroke (d), as long as the power of X or Y any one exists, the power of Z-direction exists all the time.Drawn by test of many times: same user is in the process of writing identical Chinese character, and the curve of its acting force also presents certain repeatability, based on the repeatability of force information curve as the foundation of signature analysis.

Above by reference to the accompanying drawings to invention has been exemplary description; obvious specific implementation of the present invention is not subject to the restrictions described above; as long as have employed the improvement of the various unsubstantialities that method of the present invention is conceived and technical scheme is carried out; or design of the present invention and technical scheme directly applied to other occasion, all within protection scope of the present invention without to improve.

Claims (9)

1. a hand-written multi-dimensional force information collecting device, it is characterized in that, described acquisition system comprises data acquisition module and sensor-based system signal processor, data acquisition module comprises sensor matrices, sensor matrices is arranged on to be write below region, described sensor comprises X-direction capacitor cell group and Y-direction capacitor cell group, described X-direction capacitor cell group and Y-direction capacitor cell group include capacitor cell module, the comb teeth-shaped structure that described capacitor cell module is made up of plural strip capacitor cell, each strip capacitor cell comprises the drive electrode of top crown and the induction electrode of bottom crown, described capacitor cell module comprises by two or more width a ₀length b ₀strip capacitor cell composition the first strip capacitor cell group and two or more width ka ₀length b ₀strip capacitor cell composition the second strip capacitor cell group.

2. hand-written multi-dimensional force information collecting device according to claim 1, it is characterized in that, described acquisition system also comprises display module and sensitive diaphragm, described display module connects sensor-based system signal processor, sensitive diaphragm covers sensor array surface, the length of described display module with wide compared to sensor array with identical scale smaller.

3. hand-written multi-dimensional force information collecting device according to claim 1, it is characterized in that, the drive electrode of described each strip capacitor cell is identical with induction electrode width, and the length of drive electrode is greater than induction electrode length, and drive electrode length two ends are reserved left poor position δ respectively _leftwith right poor position δ _right, b _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein, b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell.

4. hand-written multi-dimensional force information collecting device according to claim 3, is characterized in that, described poor position δ _left=δ _right, and wherein d ₀for strip capacitor cell dielectric thickness, G is the modulus of rigidity of elastic medium, τ _maxfor maximum stress value.

5. hand-written multi-dimensional force information collecting device according to claim 1, it is characterized in that, the lead-in wire that described comb teeth-shaped structure comprises more than 20 strip capacitor cells, connects one to one with strip capacitor cell, is provided with electrode separation a between adjacent two strip capacitor cells _δ.

6. hand-written multi-dimensional force information collecting device according to claim 5, is characterized in that, described parallel-plate area S=M (a ₀+ 2a _δ+ ka ₀) b ₀/ 2, wherein, M is strip capacitor cell quantity, b ₀for the length of strip capacitor cell, a ₀the width of strip capacitor cell.

7. hand-written multi-dimensional force information collecting device according to claim 1, is characterized in that, the strip capacitor cell lead-in wire of described first strip capacitor cell group and the second strip capacitor cell group is by parallel connection or be independently connected to sensor-based system signal processor.

8. hand-written multi-dimensional force information collecting device according to claim 1, is characterized in that, the width of described strip capacitor cell wherein, d ₀for dielectric thickness, E is the Young modulus of elastic medium, and G is the modulus of rigidity of elastic medium.

9. hand-written multi-dimensional force information collecting device according to claim 1, it is characterized in that, described first strip capacitor cell group and be respectively equipped with intermediate translator between the second strip capacitor cell group and sensor-based system signal processor, intermediate translator is for arranging voltage to electric capacity or frequency to the transmission coefficient of electric capacity.