CN1306386C - Direct acoustic surface wave touch screen - Google Patents

Abstract

The present invention relates to a direct acoustic surface wave touch screen which comprises transmitters arranged on corners of a touch bottom board, and a sliver-shaped receiver arranged at the edge of the bottom board. Voltage drop time appears on envelops of voltage pulse signals output by the corresponding receiver after ultrasonic waves transmitted by different transmitters are detected to be absorbed by a touch object; thus, a linear equation group determined by two different transmitters and the same touch point can be obtained, and the coordinate of the touch point is also obtained. Because a plurality of ultrasonic transmitters can be installed on the touch bottom board, the redundant design of the system can be realized by selecting different transducer combinations.

Description

The direct-injection type surface acoustic wave touch screen

Technical field

The present invention relates to a kind of touch-screen that utilizes the ultrasound examination touch point of conducting on the rigid surface, belong to technical field of computer multimedia, particularly computer media control technology field.The present invention is applicable to that various is the human-computer interaction interface of the digital information apparatus of core with the microprocessor.

Background technology

Existing surface acoustic wave touch screen all is based on 4,644,100,4,645, and 870,4,700,176,4,791,416,4,880,665,4,642, the disclosed technical design of other patent of 423 and 6,441,809 United States Patent (USP)s such as grade and internal reference thereof.The core content of these technology, be utilize touch-screen touch the base plate both sides of the edge, become 45 angles with the touch bottom edge two groups can part transmission hyperacoustic " reflection strip ", will be installed in touch the reflection of the ultrasonic transmitter institute ultrasonic waves transmitted in a corner of base plate through twice 45 of reflection strip, a ultrasonic receiver that is installed in the same side another one of transmitter corner receives and produces electric signal.Because the above-mentioned reflection strip and the distance of ultrasonic transmitter and receiver increase gradually, make ultrasound wave increase in the distance of the propagation distance that touches backplate surface with reflection strip and ultrasonic transmitter and receiver, that is ultrasound wave the increase with above-mentioned distance increases in travel-time of backplate surface, so ultrasonic receiver receives that transmitter institute ultrasonic waves transmitted arteries and veins is the pulse of a string very dense, forms the pulse envelope of certain duration.If there is soft object to contact with backplate surface, will sponge the interior ultrasound wave of travel path at this contact point place of backplate surface, the reduction of voltage amplitude appears on the corresponding time point of above-mentioned pulse envelope.Utilize the corresponding relation between time and the distance like this, put the one dimension coordinate figure that just can access the touch point by detection time.Above-mentioned one group of ultrasonic transducer (general designation of ultrasonic transmitter and receiver has been installed again, identical later on) the adjacent side of side identical other one group of ultrasonic transducer is installed, utilize same principle, just can obtain the coordinate figure of the other one dimension in touch point.Like this, just obtained the touch point at the coordinate figure that touches backplate surface.

The principle of work of sketching from above can be seen, the ultrasound wave of existing surface acoustic wave touch screen needs twice transmission and reflection through reflection strip, the ultrasonic signal that receiver is received is very faint, if in use these reflection strips have gathered dirts such as dust, will seriously undermine hyperacoustic intensity, make receiver can't receive ultrasonic signal.In the process that reality is used, existing surface acoustic wave touch screen needs periodic cleaning glass surface and reflection strip, is exactly this reason.This has influenced the convenience of using undoubtedly greatly, has increased considerably the maintenance cost of touch-screen applications equipment.Have again, the manufacturing process more complicated of these above-mentioned reflection strips, the production cost that this has just increased touch-screen has limited the popularization of using.In addition, because this touch-screen has only two groups of ultrasonic transducers, in a single day so a transducer fails is arranged, touch-screen just will be scrapped.And since the ultrasonic transmitter long-term work therefore the probability that lost efficacy under the state of high impulse power, to occur very high, this will shorten the average length of working life of touch-screen, be equivalent to increase use cost.

Summary of the invention

Purpose of the present invention is exactly the above-mentioned defective at existing surface acoustic wave touch screen, a kind of organization plan that does not need the surface acoustic wave touch screen of reflection strip is disclosed, adopt a kind of direct reception to detect hyperacoustic design proposal on surface by touch objects, eliminate the various inconvenience that reflection strip brings, reduce the use cost of touch-screen.An other purpose of the present invention is to utilize the present invention program's structural advantages, realize the Redundancy Design of ultrasonic transducer system, under the situation that the part ultrasonic transducer damages,, recover the normal function of touch-screen by the assembled scheme of automatic adjustment transducer.

Realize that foregoing invention purpose technical scheme has comprised the agent structure of existing surface acoustic wave touch screen, as the rectangular touch base plate, be installed in the ultrasonic transducer that touches on the base plate, the ultrasonic emitting driving circuit that is connected with ultrasonic transmitter, with the ultrasonic signal amplification treatment circuit that is connected with ultrasonic receiver, the A/D transducer, and be that the digital signal of core receives with the microprocessor, handle and computing circuit, and digital information processing system that the interface circuit between the host computer (using the computing machine or the computer system of this touch-screen) is formed and inner parts such as executable code thereof, but aspect structure of ultrasonic transducer and installation, adopted following technical scheme:

2～4 ultrasonic transmitters are installed on the touch base plate of touch-screen, are installed in respectively on the surface that touches 2～4 bights in 4 angles of base plate; On the surface of the opposite side on two limits that constitute each angle that above-mentioned ultrasonic transmitter has been installed, the ultrasonic receiver of strip is installed all; The signal output part of described ultrasonic receiver is of coupled connections by two signal transmission passages and two-way analog signal processing circuit respectively, and the output terminal of each analog signal processing circuit is connected with two A/D transducers respectively again; Described two A/D transducers pass through digital signal output end mouth separately respectively, are connected with the data bus of described digital information processing system;

Corresponding with the foregoing circuit structure, in the executable code of the program storage of described digital signal processing and transmission system, also include the one group of code that can control above-mentioned two signal transmission passage transmission states, this group code can be when digital information processing system instructs the driving circuit of a certain ultrasonic transmitter to drive ultrasonic transmitter emission ultrasound wave, by the above-mentioned signal transmission passage of control bus synchro control, be installed on the signal output part of lip-deep ultrasonic receiver of opposite side at edge that above-mentioned formation has been installed the bight of above-mentioned driven ultrasonic transmitter with two, be connected with above-mentioned two-way analog signal processing circuit respectively.

For the Redundancy Design of transducer system, the technical scheme below further having adopted: 4 ultrasonic transmitters are installed in respectively on 4 angles of described rectangular touch base plate; The ultrasonic receiver of strip also has 4, is installed in respectively on the surface on 4 limits that touch base plate; Described signal transmission passage is two one analog switches that cutter four is thrown, 4 stationary contacts of one are corresponding in twos in parallel with 4 stationary contacts of another respectively in these two analog switches, signal output part with 4 ultrasonic receivers is connected respectively, and its moving contact is connected with the two-way analog signal processing circuit respectively.

Said structure has formed the physical basis of transducer Redundancy Design.Do not need user's Secondary Design redundancy scheme for the transducer Redundancy Design that can realize setting, in the executable code of the program storage of described digital information processing system, also comprise one and comprised the list that all or part of possible configuration of transducer is made up, be included in the configuration that microprocessor in the above-mentioned digital information processing system could call and carry out this list, utilize the code of above-mentioned two the signal transmission passage transmission states of described control, control described analog switch by control bus, under any one transducer configuration combined situation, synchro control ultrasonic transmitter emission ultrasound wave and the above-mentioned analog switch of control receive the ultrasonic receiver of correspondence and are connected with analog signal processing circuit.

Further, the redundant combination of transducer calls for convenience, avoid user's manual intervention, in the executable code of the program storage of described digital information processing system, also comprised one group of transducer detection of code, this group code can be by control ultrasonic transmitter and receiver, emission and received ultrasonic signal judge whether the duty of ultrasonic transmitter and receiver is normal, and under the situation that the ultrasonic transmitter or the receiver of current appointment breaks down, automatically call described list according to the order of setting, test function is carried out in circulation; Obtain one group of normal transducer combinations rear drive ultrasonic transmitter and connect the ultrasonic receiver corresponding beginning to touch detection in test with this ultrasonic transmitter; Still do not obtain one group of normal transducer combinations after whole transducer combinations in testing described list after, then call error information is transferred to host computer by communication port.

From top description to technical solution of the present invention, the present invention has the advantage of following three aspects as can be known: first, because omitted the reflection strip at glass surface edge,, reduced maintenance cost so avoided influencing the phenomenon of touch-screen result of use because of the accumulation of dirt; The second, because omitted these reflection strips, also greatly simplified the production technology of touch-screen, reduced production cost, help popularizing and use; The 3rd, the Redundancy Design structure of transducer has guaranteed that under the situation of part transducer fails, touch-screen still can normally use, and is equivalent to prolong several fold the serviceable life of touch-screen, is equivalent to greatly reduce user's update cost.

Description of drawings

Describe some specific embodiments that can realize above-mentioned various goals of the invention in detail below in conjunction with accompanying drawing.

Caption:

Fig. 1: the principle schematic that the ultrasound wave direct projection is propagated

Fig. 2: with Fig. 1 time corresponding one waveform voltage signal

Fig. 3: a kind of generally speaking direct projection circulation way of using realizes the structure principle chart that the touch point is detected

Fig. 4: the structural principle synoptic diagram of redundant transducer designs

Fig. 5: the structural representation of the direct-injection type surface acoustic wave touch screen of basic boom

Fig. 6: a kind of structural representation of the direct-injection type surface acoustic wave touch screen with Redundancy Design

Fig. 7: the structural representation of the direct-injection type surface acoustic wave touch screen of another basic boom

Fig. 8: the basic structure of ultrasonic receiver and touching the installation diagram of bottom edge

Fig. 9: the installation site synoptic diagram between a kind of ultrasonic transmitter and the receiver

Figure 10: a kind of program flow diagram of the microprocessor internal corresponding with Fig. 5,7 structures

Figure 11: a kind of program flow diagram of the microprocessor internal corresponding with Fig. 6

Figure 12: transducer all disposes combination table

Embodiment

Can see from Fig. 1 and Fig. 2, not exist that the ultrasonic waves transmitted pulse of ultrasonic transmitter E institute just can be positioned at this transmitter opposite, receive for the bar shaped receiver of D with the transmitter distance if absorb hyperacoustic touch objects; At this moment ultrasound wave is that spread towards periphery in the center of circle with the transmitter on the surface of base plate, and after one section travel-time T, receiver can receive ultrasound wave, produces electric signal.If the velocity of propagation (the back abbreviation velocity of sound) of ultrasound wave in base plate represents then have with v

D＝vT

Because the two ends of receiver R and the distance of transmitter are inequality, wherein an end and transmitter are nearest, more and more far away along the receiver long axis direction from transmitter, ultrasonic pulse 101 will be from an end of receiver like this, " inswept " whole piece receiver, thereby the diverse location of receiver all can passing in time produce electric signal in proper order, and the electric signal exported of receiver is exactly the duration broad pulse envelope 201 that is Δ T like this.Concentric camber line among Fig. 1 is represented the process that the ultrasound wave diffusion is propagated, and wherein solid line is represented the position of crest, and dotted line represents that crest spreads the position of propagating arrival constantly in difference.If a touch objects P is arranged on hyperacoustic travel path, touch objects will sponge a part of ultrasound wave so, extend to receiver R direction along the line between transmitter and the touch objects, with the intersection point place of receiver R, the electric signal that is produced will be when not having touch objects a little less than, promptly after receiving ultrasound wave, arrive Δ t during the moment, the amplitude of receiver output electric signal can obviously reduce, as shown in Figure 2, and the voltage V of sensor output at this moment _pJust less than just often voltage V _mBecause the relation of the position between transmitter and the receiver is known,, just can obtain equation by the straight line of an E and some P as long as measure Δ t so.If as shown in Figure 3, the mounted on surface at base plate has two ultrasonic transmitter E _AAnd E _B, and receiver R between distance be respectively D _AAnd D _B, so by measuring the time Δ t of electric voltage dropping point on two voltage envelope 301,302 of output _AWith Δ t _B, just can obtain the equation of the straight line of two connection transmitters and touch point, find the solution the intersection point of these two straight lines, can obtain the coordinate of touch point.But because structure shown in Figure 3 the effective coverage that can detect very little, so do not possess very strong practicality, only be a kind of explanation to principle.And adopt the structure of back, and just can reach very wide sensing range, reach the requirement of practicability.

Various possible embodiments quantitatively are described in the structural framing of principle shown in this figure below in conjunction with Fig. 4.

In the installation site synoptic diagram of the transmitter of simplification shown in Figure 4 and receiver, the 401st, the touch base plate plate of sensor installation, it is that a, width are b that setting needs the length of the rectangular area of detected touch point, and is that initial point is set up rectangular coordinate system X0Y with an angle in this zone.Four ultrasonic transmitters are installed on four angles of rectangular area, its coordinate be respectively E1 (0,0), E2 (0, b), E3 (a, b) and E4 (a, 0), represent with R1, R2, R3, R4 respectively on four limits of above-mentioned zone by 4 ultrasonic receivers of installation.Clear for narrating, here utilize the diagonal line of rectangle, above-mentioned rectangular area is divided into 1,2,3,4 totally four zonules again, and respectively be provided with a touch point P (x respectively two cornerwise above and belows, y) and P ' (x ', y '), so that analyze as touch point P (x, y) when being positioned at zones of different, the relation between touch point and each ultrasonic transmitter.But all (x y) represents with P when analyzing.

For theory structure of the present invention more clearly is described, below with the new symbol of definitional part, the mathematical relation that is used for the back is derived.These symbols are as follows:

T _a: from the transmitter ultrasonic waves transmitted, behind distance a, arrive receiver R1 or needed transit time of R3;

T _b: from the transmitter ultrasonic waves transmitted, after distance b, arrive receiver R2 or needed transit time of R4;

Δ t _Nu, (n=1,2,3,4): the Δ t that the expression ultrasound wave produces during along 0 → X, 0 → Y direction is inswept each receiver;

Δ t _Nd, (n=1,2,3,4): the Δ t that the expression ultrasound wave produces along X → 0, during Y → 0 direction is inswept each receiver.

Simultaneously, continue to use other notations similar to the front again, derivation is by the equation of the straight line of above-mentioned four ultrasonic transmitters and touch point respectively.

(x y) is positioned at zone 1, zone 2 o'clock, establish the be touched shade that stays after the thing absorption of transmitter E1 (0,0) ultrasonic waves transmitted and stay the central point of projection on receiver R2, and the distance between the transmitter E1 is D1, has as touch point P $D_1=(T_b+\mathrm{\Δ}{t}_{2u})v=\sqrt{{x_1}^2+b^2}$

Can get $x_1=\sqrt{{(T_b+\mathrm{\Δ}{t}_{2u})}^2{v}^2-b^2}$

Obtain straight-line equation: $y=\frac{\mathrm{bx}}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{2u})}^2{v}^2-b^2}}...\left(1\right)$

(x y) is positioned at zone 3, zone 4 o'clock, and above-mentioned shade is D2 at the central point of projection on the receiver R3 and the distance between the transmitter E1, then has as touch point P

$D_2=(T_a+\mathrm{\Δ}{t}_{3u})v=\sqrt{a^2+{y_1}^2}$

$y_1=\sqrt{{(T_a+\mathrm{\Δ}{t}_{3u})}^2{v}^2-a^2}$

Obtain straight-line equation: $y=\frac{\sqrt{{(T_a+\mathrm{\Δ}{t}_{3u})}^2{v}^2-a^2}}{a}x...\left(2\right)$

(0, b), when the touch point is positioned at zone 2, zone 3 the time, above-mentioned shade is D3 at the central point of projection on the receiver R3 and the distance between the transmitter E2, then has for transmitter E2

$D_3=(T_a+\mathrm{\Δ}{t}_{3d})v=\sqrt{a^2+{(b-y_2)}^2}$

Because y2 is less than b, so $y_2=b-\sqrt{{(T_a+\mathrm{\Δ}{t}_{3d})}^2{v}^2-a^2}$

Thereby must straight-line equation $y=\frac{\sqrt{{(T_a+\mathrm{\Δ}{t}_{3d})}^2{v}^2-a^2}}{a}x+b...\left(3\right)$

When the touch point is positioned at zone 1, zone 4 the time, above-mentioned transmitter shade is D4 at the central point of projection on the receiver R4 and the distance between the transmitter E2, then has

$D_4=(T_b+\mathrm{\Δ}{t}_{4u})v=\sqrt{b^2+{x_2}^2}$

$x_2=\sqrt{{(T_b+\mathrm{\Δ}{t}_{4u})}^2{v}^2-b^2}$

Also obtain straight-line equation $y=b(1-\frac{x}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{4u})}^2{v}^2-b^2}})...\left(4\right)$

(a, b), when the touch point is positioned at zone 1, zone 2 the time, above-mentioned shade is D5 at the central point of projection on the receiver R1 and the distance between the transmitter E3, then has for transmitter E3

$D_5=(T_a+\mathrm{\Δ}{t}_{1d})v=\sqrt{a^2+{(b-y_3)}^2}$

Because y3 is less than b, so $y_3=b-\sqrt{{(T_a+\mathrm{\Δ}{t}_{1d})}^2{v}^2-a^2}$

Obtain straight-line equation $y=\sqrt{{(T_a+\mathrm{\Δ}{t}_{1d})}^2{v}^2-a^2}(\frac{x}{a}-1)+b...\left(5\right)$

When the touch point is positioned at zone 3, zone 4 the time, above-mentioned transmitter shade is D6 at the central point of projection on the receiver R4 and the distance between the transmitter E2, then has

$D_6=(T_b+\mathrm{\Δ}{t}_{4d})v=\sqrt{{(a-x_3)}^2+b^2}$

Because x3 is less than a, so $x_3=a-\sqrt{{(T_b+\mathrm{\Δ}{t}_{4d})}^2{v}^2-b^2}$

And then obtain straight-line equation $y=b(\frac{x-a}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{4d})}^2{v}^2-b^2}}+1)...\left(6\right)$

At last, for transmitter E4 (a, 0), when the touch point is positioned at zone 2, zone 3 the time, above-mentioned shade is D7 at the central point of projection on the receiver R3 and the distance between the transmitter E4, then has

$D_7=(T_b+\mathrm{\Δ}{t}_2)v=\sqrt{{(a-x_4)}^2+b^2}$

Because x4 is less than a, so $x_4=a-\sqrt{{(T_b+\mathrm{\Δ}{t}_{2d})}^2{v}^2-b^2}$

And then obtain straight-line equation $y=\frac{b(a-x)}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{2d})}^2{v}^2-b^2}}...\left(7\right)$

When the touch point is positioned at zone 4, zone 1 the time, above-mentioned transmitter shade is D8 at the central point of projection on the receiver R1 and the distance between the transmitter E4, then has

$D_8=(T_a+\mathrm{\Δ}{t}_{1u})v=\sqrt{{y_4}^2+a^2}$

So $y_4=\sqrt{{(T_a+\mathrm{\Δ}{t}_{1u})}^2{v}^2-a^2}$

Obtain straight-line equation thus $y=-(\frac{x}{a}+1)\sqrt{{(T_a+\mathrm{\Δ}{t}_{1u})}^2{v}^2-a^2}...\left(8\right)$

When having obtained the touch point and be positioned at diverse location, connect the equation of touch point and 8 different straight lines of each ultrasonic transmitter by top analysis.Like this,, use top different straight-line equations to constitute system of equations, just can access the touch point at the coordinate figure that detects the surface when we set the touch point of using different ultrasonic transmitters and receiver to come the senses touch backplate surface.For example, when we use ultrasonic transmitter E2 (0, b) and E4 (a, 0) come detected touch point, just can find the solution the system of equations that constitutes by straight-line equation (3), (7) or (4), (8)

$\left\{\begin{array}{c}y=-\frac{\sqrt{{(T_a+\mathrm{\Δ}{t}_{3d})}^2{v}^2-a^2}}{a}x+b\\ y=\frac{b(a-x)}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{2d})}^2{v}^2-b^2}}\end{array}\right....\left(9\right)$

Perhaps

$\left\{\begin{array}{c}y=b(1-\frac{x}{\sqrt{{(T_b+\mathrm{\Δ}{t}_{4u})}^2{v}^2-b^2}})\\ y=-(\frac{x}{a}+1)\sqrt{{(T_a+\mathrm{\Δ}{t}_{1u})}^2{v}^2-a^2}\end{array}\right....\left(10\right)$

Obtain the coordinate of touch point.In reality is implemented, select system of equations (9) still (10), according to behind certain transmitter emission ultrasound wave, can on receiver R1, R4 still are the signal exported of R2, R3, detect Δ t and decide.As shown in Figure 4, if on the electric signal of R1 output, detect Δ t _1u, so necessarily also can on the output signal of R4, detect Δ t _4u, and can not on the signal that R2, R3 exported, detect Δ t _2d, Δ t _3d, at this moment just should use system of equations (10) to find the solution the coordinate figure of touch point, system of equations (9) can not occur; If reverse situation promptly can only obtain Δ t in the signal of R2, R3 output _2dPerhaps Δ t _3d, at this moment system of equations (10) can not set up, and can only use system of equations (9) to find the solution the coordinate figure of touch point.

If use the ultrasonic transmitter that is installed in the same side of touch base plate to come the position of detected touch point, situation can be complicated a little.For example (0, b) emission ultrasound wave as seen from Figure 4, when the touch point is positioned at the zone 1 the time, needs to use the coordinate figure that is obtained the touch point by equation (1) and (4) formation system of equations from ultrasonic transmitter E1 (0,0), E2; In the time of within the touch point is positioned at zone 2, need to use by equation (1) and (3) to constitute the coordinate figure that system of equations obtains the touch point; And when being positioned within regional 3 or 4 when the touch point, then need respectively to use by equation (2) and (3) or (2), (4) to constitute the coordinate figure that system of equations obtains the touch point.Identical with the front, determine the end to use which system of equations to obtain the coordinate figure of touch point, still, can connect at which and detect Δ t on the receiver according to after launching ultrasound wave when certain transmitter _NuPerhaps Δ t _NdDecide.

For other various combinations, use same rule and just can obtain configuration between transmitter, the receiver and the relation between employed straight-line equation and the system of equations, thereby determine how to obtain the relationship of touch point coordinate figure.Because these contents are very simple, so need not list one by one at this.As overall conclusion, accompanying drawing 12 has provided when using structure shown in Figure 4, whole possible transducer combinations schemes, and find the solution the straight-line equation group that the touch point coordinate time need be used.In accompanying drawing 12, the system of equations of straight-line equation and formation thereof is still used aforesaid numeral flag.

When actual product designed, in order to protect ultrasonic transducer, actual available touch surveyed area was less than the long rectangular extent of taking advantage of the wide a*b of equaling, the scope of being surrounded as dotted line among the figure 402.In fact, mathematical derivation by less complex, the zone that ultrasonic receiver surrounded of four strips needn't be a rectangle as can be known, as long as know the installation coordinate of each ultrasonic transducer, other shape surveyed area still still can use the detection architecture of this direct-injection type.But the surveyed area of other shape is seldom used in practice, therefore is not described further in the present invention.Simultaneously, the installation site coordinate of above-mentioned ultrasonic transducer also not necessarily will be set according to the given minimalist program in front, fully can actual conditions freely sets up coordinate system and sets.

Described mathematical principle of the present invention and basic structural model above in detail, below will be further several concrete structure of the present invention be described with the mode of embodiment.

What Fig. 5 showed is to implement a kind of basic electromechanical structure of the present invention.Among the figure, R1～R4 is the ultrasonic receiver of four strips as before, is installed in four edges that the surface that touches base plate needs the zone of detected touch point.Here, comprise various embodiment of the present invention, base plate 401 just requires rectangular at the edge of touch point surveyed area 402, and the shape outer as for receiver is unimportant; If touch-screen is used for the surface of display, then need to use transparent glass material, if only use as the Trackpad that does not show the host computer content in real time, then other opaque elastic materials such as pottery, metal can use, and do explanation this spy.Bight on the diagonal of rectangle surveyed area, two ultrasonic transmitter E1 (0,0) and E3 are installed, and (a b), is driven device 501,502 via lead 505 respectively and drives and the emission ultrasound wave.These two drivers are controlled by the digital information processing system that with MCU is core by control line 503,504.Four ultrasonic receivers also are connected to the input end of signal transmission passage 507,508 via lead 505, and are of coupled connections by this passage and two-way analog signal processing circuit.Here be called and be of coupled connections, because signal is just to connect through certain process, for different transducer configuration mounting structures, this process also is different.But the primary element that serves as the signal transmission passage 507,508 among Fig. 5 is the analog switch of two " single-pole double-throw (SPDT)s ", is controlled by digital information processing system 515 by control bus 506 in the present invention.Here said " single-pole double-throw (SPDT) ", expression has two groups of signalling channels: if ultrasonic receiver is differential output, so every " cutter " just should have two bars passages; If single-ended output, so every " cutter " just only needs one tunnel signalling channel, and the connotation of " cutter " that the back relates to analog switch is identical.Each analog switch here all has two groups of stationary contacts (to be made as input end, later on together), our definition is when the control signal of analog switch is identical, (be made as output terminal with moving contact, later on together) that group input end that on-state is identical is input end of the same name (or stationary contact of the same name), like this, ultrasonic receiver with the connected mode of analog switch the best is exactly: the output terminal of R1, R4 is connected with the signal input part of the same name of two analog switches respectively with R2, R3 output terminal, can realize the simplest control mode like this.Because when E1 emission ultrasound wave, the signal that has only R2, R3 to receive is effective, and when E3 emission ultrasound wave, the ultrasonic signal that also has only R1, R4 to receive is effective.Including the analog signal processing circuit 509,510 of functions such as amplification, filtering and A/D transducer 511,512 and output transform result's thereof data bus 513,514 in the analog switch back all is two-way, because touch point position is unknown, so the signal that circuit part needs simultaneously two ultrasonic receivers R1, R4 or R2, R3 to be exported is handled, obtain two groups of data to be compared, that handle, then " find " straight-line equation that is suitable for.This technical scheme shown in Figure 5, except the numerical evaluation of structure, installation form and the digital information processing system inside of front transducer and program code and carry out the program code of signalling channel, A/D convertor controls, other principle of work and number are 4,644,100,4,645,870,4,700,176,4,791,416,4,880,665 and 6,441,809 United States Patent (USP)s such as grade, and the disclosed technical scheme of other patents that they relate to is identical, but reference implementation.At last, the net result that obtains through computing through data line 516 outputs, is transferred to host computer by the interface (PORT) 517 with host computer.

In the present invention, the core of digital information processing system 515 is microprocessor (MCU), can be general or special-purpose Single Chip Microcomputer (SCM) system, also can use DSP (digital signal processor), optionally the processing speed of computational data amount, requirement and deciding.Under most of situation (the detection sample frequency of p.s. is not very high), a lot of existing New Type of Chip Microcomputer system can be competent at.The structure of this system core part is identical with the kernel of the digital information processing system that other occasion is used, and all is to be made of CPU, ROM, RAM, controller and I/O port.For application-specific of the present invention, also comprise other peripheries such as data latches.

The process flow diagram of digital processing system internal core program code is seen Figure 10.System begins to start from step 1001, carries out transducer subsequently and detects step 1002, and whether the work by determining step 1003 detection transducers is normal again.If normal, just begin by the control line driver, drive first ultrasonic transmitter emission ultrasonic pulse, and connect synchronously and first two ultrasonic receivers reception ultrasound wave that transmitter is corresponding from step 1004.Otherwise, jump to step 1015, by data transmission step 1014 to the host computer output error message.Connect the sound of output by ultrasonic receiver---be sent to the A/D transducer after the electric signal process analog circuitry processes, quantize, carry out memory command 1006 again and store the two-way quantized data into working storage through step 1005 control simulating signal.Step 1007,1008, second parts work such as ultrasonic transmitter of 1009 controls, the operation of repeating step 1004～1006.After having obtained four quantized datas, carry out data reading command 1010, read temporary data and judge that Δ t appears in the output of which two receiver, for the data processing evaluation work of back is got ready.

Data processing, calculation procedure 1011 are cores of data processing.When can having two kinds of schemes for enforcement, the run time version of this part selects.First kind is to carry out to set up two corresponding straight-line equations and constitute system of equations, find the solution the program code of this system of equations etc. then, finally obtain the touch point coordinate P (x, y).If be operated in this state, system also needs to carry out the derivation of the straight-line equation (1) that calls according to the front, (5), (2), (6), for reducing the step 1012 that operand has been set up the step 1013 of " the straight-line equation model bank " finished, carried out " current calibration data " that form, that be used for the calibration calculations result when being invoked at touch screen calibration.The advantage of this mode is that data processing is more stable, be not easy to be subjected to the influence of extraneous factor, shortcoming is because the workload of numerical evaluation is very big, if obtain comparing higher processing speed, to the requirement of hardware performance than higher, to cause production cost to improve, otherwise phenomenon such as delay of response will occur and influence normal use.Second kind is after MCU only does the Δ t time signal that obtains the mark of one suitable straight-line equation, directly to be sent in the host computer, finishes operations such as straight-line equation foundation, coordinate figure calculating by means of the powerful numerical evaluation function of host computer (generally being PC).In this case, aforesaid " straight-line equation model bank " and " current calibration data " can directly be stored in the storer of host computer, its relative merits are just in time opposite with first kind of scheme, requirement to MCU reduces greatly, production cost is also cheaper, but be subjected to the influence of host computer duty easily, especially when host computer moves some large programs, also be easy to generate phenomenons such as delay of response even deadlock.Because step 1011 has two kinds of above-mentioned basic schemes, therefore in Figure 10, relevant step, operation and data content all with dashed lines represented to show differentiation.But, no matter use any scheme, resulting data all will be sent data by the communication excuse by data transmission procedure 1014.

The embodiment of another one basic structure sees Fig. 7.Compare with basic structure shown in Figure 5, the key distinction of this framework is the mounting structure of ultrasonic transducer---ultrasonic transmitter is not the diagonal angle, and is mounted in a side of base plate; Receiver only need be installed three, is installed in to touch low three other edges of plate; The analog switch that constitutes signalling channel also only needs one, and the another one signalling channel directly substitutes with lead.Because no matter which transmitter is launched ultrasound wave, receiver R4 must export electric signal, could guarantee the integrality of detection, so need whether not work with specific transmitter, all should be access in analog signal processing circuit.Therefore.This structure also is the 4th a kind of array mode of transducer given in the accompanying drawing 12, although the straight-line equation that will relate to still is four as can be known, but the combination of system of equations has four kinds also, therefore according to Δ t judge use which system of equations to find the solution the process of touch point coordinate can be complicated a little, the content of other structures and operation, identical with structure shown in Figure 5, to be production cost further reduce because of the minimizing meeting of components and parts advantage, shortcoming is at different surveyed areas, the physical resolution that detects can be more inhomogeneous, may be not suitable in some cases.The employed software configuration of this structure, basically the program flow diagram with shown in Figure 10 is identical, the key distinction is because relate to more straight-line equation, so step 1010,1011 code structure are more complicated, the control analog switch is then simpler relatively with the code that ultrasonic transmitter switches receiving sensor.

Fig. 6 is represented is the present invention on the basis of the given basic structure of Fig. 5 or Fig. 8, has increased the basic embodiment of Redundancy Design.Compare with Fig. 5, this structure has increased by two ultrasonic transmitter E2 and E4, has promptly all installed one on each angle that touches base plate, cooperates therewith, driver also is increased to 601,602,603,604 totally 4 by two, controls by control line 605,606,607,608 respectively.Like this, according to the result who obtains from Fig. 4, the possible array mode of transducer is abundanter, can realize whole combinations given in the accompanying drawing 12, the serviceable life of having improved touchscreen greatly.Such as, the setting of supposing acquiescence when touchscreen dispatches from the factory is to use two transmitters of E1, E3, cause E1 to damage owing to work long hours continuously, finding E1 when the self-check program of touch-screen so damages, just can automatically or point out user, guardian to be replaced by use E2, E4 the ultrasonic transmitter of equivalence basically, guarantee that touchscreen continues operate as normal for giving tacit consent to.If E2 damages again after a period of time, can also to continue to change the transmitter of acquiescence be E3, E4 in system so.Therefore this design can increase substantially the serviceable life of product under the condition that increases few production cost.Compare with Fig. 5, the change of another one details is that analog switch becomes " cutter four is thrown " by 609,610 " dpdt double-pole double-throw (DPDT)s " on the circuit structure, this variation be for the combination accessory of transducer.In order to make data handling system the simplest to the control analog switch, the signal output part of ultrasonic receiver preferably is connected according to the mode among the figure with connected mode between the input end of analog switch: the input end of the same name of supposing two analog switches label respectively is " 1～4 " and " one～four ", after the order parallel connection of end of the same name for two analog switches, be connected with the signal output part of R1-R4 more so according to " 1 ∥ two, 2 ∥ three, 3 ∥ four, 4 ∥ one ".Like this, when the control end of two simulations receives identical control signal, can guarantee that two adjacent ultrasonic receivers receive transmitter ultrasonic waves transmitted signal on the angle, opposite.If connect not according to such rule, still can be according to list 1, finish the switching of receiver with the work of ultrasonic transmitter, but control routine and control bus 506 or circuit will be complicated, every analog switch will be controlled separately.

The program flow diagram corresponding with Fig. 6 seen Figure 11.With Figure 10 relatively, Figure 11 is many in the execution of relevant selection transducer combinations step 1101-1106 perhaps, other parts are identical with Figure 10.When the detection step 1003 that executes the acquiescence transducer and after finding the acquiescence transducer fails, program is not directly to jump to 1015 indication error messages, but forward the step 1101 that the transducer combinations list is selected to, from this list according to preestablishing first group of standby transducer combinations of select progressively, according to the execution in step 1102 of 1002,1003 same way as, carry out new transducer combinations tested.If new test can operate as normal through this combination of determination step 1103 proofs, so with regard to execution in step 1104.Step 1104 can be regarded as the inlet of the appointment that program returns, because can have two kinds of operation schemes selective in this step.Operation is to inform that by the indication of display the user recalibrates touch-screen in first, and preserves calibration data by step 1106; Second kind of operation be from " calibration data base ", directly call or mark before (can when using for the first time, all transducer combinations all be calibrated once, and preserve calibration data) calibration data of having produced, use during for the back numerical evaluation.Execution in step 1105 is preserved the current selection conduct transducer combinations of acquiescence later on then, returns master routine and continues to carry out following step.Certainly, step 1104 and 1105 order can be exchanged, and can not influence execution result.Also include the transducer unit that had lost efficacy and can not use if the result of determination step 1103 is these transducer combinations, so just judge whether to test combinations all in the list 1 by next determination step 1107, if the result is Yes, represent that all transducer combinations are all tested, it is too many to illustrate that transducer damages, touch-screen can't continue to use, at this moment with regard to execution in step 1015 prompting error messages; Otherwise return step 1101, from list, select next transducer combinations to continue test.

Certainly, this Redundancy Design also can use 3 ultrasonic transmitters to constitute the smaller design proposals of redundance.But angle from " P/C " ratio, obviously not preferred plan, because (life-span of two transmitters should be similar in theory at this moment can only to produce the redundance of one times of less than in theory, not that lost efficacy with do not have used that combination after, mission life depends on by original that does not temporarily have the life-span of the transmitter of inefficacy), and use 4 transmitters, the above redundance of twice is just arranged in theory.

In addition, the structure of Fig. 6 also can be used 4 transmitter work together, does for the first time for two one group and detects, and other two one group is used for verification to improve the resolution or the precision of touch-screen.But under most of situation, this verification not necessarily, because it is the size of finger is very large size for the resolution or precision that only can reach when two transmitters are used to detect, more reasonable not as being used for Redundancy Design with other two.And if add the secondary checking procedure, the workload of data processing will double, will be higher to the requirement of parts such as MCU.

Fig. 8 is the basic structure and the scheme of installation on the touch base plate thereof of strip ultrasonic receiver.801 expression piezoelectrics among the figure, the 802, the 803rd, two electrodes of receiver.This sensor can be formed in parallel with a plurality of little receivers, perhaps according to the thin-and-long sensor of the size specialized designs certain-length of touch-screen.

Fig. 9 is the relation of the installation site between ultrasonic transmitter and the receiver generally speaking.In the ordinary course of things, an end of ultrasonic receiver and the actual range of transmitter will be greater than straight line that passes through the receiver axis county and the minor increments between the transmitter.But as long as according to the relation between the leg-of-mutton length of side, calculate actual range DT between receiver near-end and the transmitter according to providing formula among the figure, survey or calculate ultrasonic propagation again and spend this needed transit time of distance, in order to substitute Ta and the Tb in the straight-line equation of front, still can obtain correct result.

In fact, the present invention can also have the design proposal of a variety of accommodations, but basic mathematical principle, the counter structure between the transducer, basic software and hardware structure all do not have very big difference, flexible Application in practice.

Claims (6)

1. direct-injection type surface acoustic wave touch screen, by the rectangular touch base plate, be installed in the ultrasonic transducer that touches on the base plate, the ultrasonic emitting driving circuit that is connected with ultrasonic transmitter, with the ultrasonic signal amplification treatment circuit that is connected with ultrasonic receiver, A/D transducer, and be digital signal reception, processing and the computing circuit of core and the digital information processing system that the interface circuit between the host computer is formed with the microprocessor, it is characterized in that:

Described ultrasonic transmitter has 2～4, is installed in respectively on the surface that touches 2～4 bights in 4 angles of base plate; Installed on the surface of opposite side on two limits at angle of above-mentioned ultrasonic transmitter at each, the ultrasonic receiver of strip all has been installed; The signal output part of described ultrasonic receiver, the input end by two signal transmission passages and two-way analog signal processing circuit is of coupled connections respectively, and the output terminal of each analog signal processing circuit is connected with two A/D transducers respectively again; Described two A/D transducers pass through digital signal output end mouth separately respectively, are connected with the data bus of described digital information processing system;

Corresponding with the foregoing circuit structure, in the program storage of described digital signal processing and transmission system, include the one group of executable code that can control above-mentioned two signal transmission passage transmission states, this group code can be when digital information processing system instructs the driving circuit of a certain ultrasonic transmitter to drive ultrasonic transmitter emission ultrasound wave, by the above-mentioned signal transmission passage of control bus synchro control, signal output part with the lip-deep ultrasonic receiver of the opposite side at two edges that are installed on the above-mentioned bight that ultrasonic transmitter has been installed is connected with above-mentioned two-way analog signal processing circuit respectively.

2. direct-injection type surface acoustic wave touch screen according to claim 1 is characterized in that: described ultrasonic transmitter has 2, is installed in respectively on two angles that diagonal line connected of described rectangular touch base plate; Described strip ultrasonic receiver has 4, is installed in respectively on the surface at 4 edges of described touch base plate, and described signal transmission passage is the analog switch of two single-pole double-throw (SPDT)s; Two stationary contacts of the same name of every analog switch all are connected with the signal output part of two ultrasonic receivers that are positioned at described touch base plate both sides respectively, and the moving contact of analog switch is connected with the input end of above-mentioned two-way analog signal processing circuit.

3. direct-injection type surface acoustic wave touch screen according to claim 1 is characterized in that: described ultrasonic transmitter has 2, is installed in described rectangular touch base plate respectively with on two angles on one side; Described strip ultrasonic receiver has 3, is installed in respectively on the surface at other 3 edges of described touch base plate; In these ultrasonic receivers, the signal transmission passage that is connected with ultrasonic receiver on being installed in two limits that touch the base plate both sides, it is the analog switch of a single-pole double-throw (SPDT), two stationary contact end is connected with the signal output part of two ultrasonic receivers respectively, and its moving contact end is connected with one road analog signal processing circuit; The signal transmission passage that is connected with an other ultrasonic receiver is a lead, and promptly this ultrasonic receiver directly is connected with other one road analog signal processing circuit by lead.

4. direct-injection type surface acoustic wave touch screen according to claim 1 is characterized in that: described ultrasonic transmitter has 4, is installed in respectively on 4 angles of described rectangular touch base plate; Described strip ultrasonic receiver has 4, is installed in respectively on the surface on 4 limits that touch base plate; Described signal transmission passage is two one analog switches that cutter four is thrown, 4 stationary contacts of one are corresponding in twos in parallel with 4 stationary contacts of another respectively in these two analog switches, be connected with the signal output part of every ultrasonic receiver respectively, the moving contact of analog switch is connected with the two-way analog signal processing circuit respectively.

5. direct-injection type surface acoustic wave touch screen according to claim 4, it is characterized in that: in the executable code of the program storage of described digital information processing system, also include one and comprise the list that all or part of possible configuration of transducer is made up, be included in the configuration that microprocessor in the above-mentioned digital information processing system could call and carry out this list, utilize the code of above-mentioned two the signal transmission passage transmission states of described control, control described analog switch by control bus, under any one transducer configuration combined situation, synchro control ultrasonic transmitter emission ultrasound wave and the above-mentioned analog switch of control are connected the ultrasonic receiver of correspondence with analog signal processing circuit.

6. direct-injection type surface acoustic wave touch screen according to claim 5, it is characterized in that: in the executable code of the program storage of described digital information processing system, also include one group of transducer detection of code, this group code can be by control ultrasonic transmitter and receiver, emission and received ultrasonic signal judge whether the duty of ultrasonic transmitter and receiver is normal, and under the situation that the ultrasonic transmitter or the receiver of current appointment breaks down, automatically call described list according to the order of setting, test function is carried out in circulation; Obtain one group of normal transducer combinations rear drive ultrasonic transmitter and connect the ultrasonic receiver corresponding beginning to touch detection in test with this ultrasonic transmitter; After in testing described list, all still not obtaining one group of normal transducer combinations after the transducer combinations, then call error information, by and described host computer between interface circuit be transferred to host computer.

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