CN101089802A - 2D position sensor - Google Patents

Abstract

The invention relates to a two-dimensional position sensor comprising a substrate with a sensing area defined by a pattern of electrodes comprising electrodes for determining an x-position and electrodes for determining a y-position. The x-electrodes and the y-electrodes extend generally in the x-direction and are interleaved in the y-direction. The x-electrodes comprise at least a first, a second and a third group of elements formed such that adjacent ones of the elements of different sets of x-electrodes are coextensive along the x-direction such that the x-electrodes can provide ratiometric capacitive signals, thereby providing quasi-continuous x-position sensing throughout the sensing area. In addition, the y electrodes may be resistively connected or arranged in ratiometric pairs to provide quasi-continuous y-position sensing. Alternatively, the set of x electrodes can be interdigitated to form blocks of different areas adjacent in the x direction to provide stepped x position sensing in combination with stepped y position sensing provided by the y electrodes.

Description

2D position sensor

technical field

The present invention relates to two-dimensional capacitive position sensors typically actuated by a human finger or stylus. Example devices include touch screens and touch pads, especially over liquid crystal displays (LCDs) or cathode ray tubes (CRTs) and other types of displays, stylus input tablets, or encoders in devices used for feedback control purposes those touchscreens and touchpads.

Background technique

References to stylus or touch input for machines date back to at least 1908, as embodied in patent DE 203,719 [1].

Touch screens and pointing devices are becoming increasingly popular and ubiquitous, not only for personal computers but also for various other devices such as personal digital assistants (PDAs), point-of-sale (POS) terminals, electronic information and ticket kiosks, kitchen appliances, etc. equipment. These devices continue to evolve into lower priced products, resulting in the need to continually reduce production costs while maintaining high levels of quality and stability.

Touch screens are generally divided into two types: capacitive and resistive.

With respect to capacitive devices, the term "2-dimensional capacitive sensor" or "2DCT" is used without limitation to refer to devices with at least two-dimensional coordinates (DCT) related to the position of an object or body part that can be reported through a capacitive sensing mechanism. Carr coordinates or other coordinates) and touch screens, touch sensor pads, proximity sensing areas for position sensing of mechanisms or feedback systems; displays overlaid on LCD, plasma screens, or CRT screens, etc. screen overlay touchscreen; or other type of control surface, etc.

For resistive devices, the term "2-dimensional resistive sensor" or "2DRT" is used to generically refer to touch screen or stylus input devices based on pure galvanic principles.

The term "2DxT" refers to elements of the 2DCT or 2DRT type.

The term "touch" means contact or proximity of a body part or mechanical part of sufficient strength to produce a capacitive signal of the desired output. In the sense of "proximity", touch can also mean "pointing at" the 2DCT without direct physical contact, where the 2DCT can respond to capacitance due to objects close enough to elicit an appropriate response.

The term "element" refers to an active sensing element of a 2DCT or 2DRT. The term "electrode" refers to a connection point on the periphery of a component.

The term "stripe" refers to a wire conductor that is an integral part of the element and has two ends. The strips can be wires. The strips can have intentionally considerable galvanic resistance, while the wires have the least resistance. If the element it belongs to is physically curved, the strip will also be physically curved.

The term "pin cushion" refers to any distortion of the signal from a 2DCT, whether parabolic, barrel or other shaped 2D deformation.

Many types of 2DCT are known to suffer from geometric distortions characterized as "pincushion distortion" or "hyperbolic" or "parabolic" whereby the reported touch coordinates are in error due to electrical effects on the sensing surface. These effects are described in greater depth in various other patents, such as Pepper's US 4,198,539 [2], which is incorporated by reference. Excellent summaries of the known causes of geometric distortions, their solutions and the problems of their solutions can be found in US 5,940,065 [3] and US 6,506,983 [4] of Babb et al., which are incorporated by reference. US 5,940,065 [3] briefly describes two main classes of correction: 1) electromechanical methods involving the design or modification of the sensing surface or connecting electrodes; 2) modeling methods that correct distortions with mathematical algorithms.

electromechanical method

Edge processing of planar components: Küpfmüller et al. in US 2,338,949 [5] (applied in 1940) use very long rectangular tails on X and Y to surround a small usable area to solve the edge distortion problem in 2DRT electronic diagrams . Küpfmüller took the further step of cutting these four trailing slots into individual strips; these strips do not intrude into the user input area, but do serve to increase the resistance to the current flow in a non-uniform manner along the sides parallel to it. This idea reappeared almost 50 years later in a slightly different form in US 4,827,084 [6] by Yaniv et al. Küpfmüller is still the most similar prior art to the present invention.

Becker first described 2DRT electronics in US 2,925,467 [7] to eliminate nonlinear edge effects by using edge materials with resistance much lower than the intrinsic sheet resistance of the element. This method can also be used to construct 2DCT.

Pepper, in patents US 4,198,539 [2], US 4,293,734 [8] and US 4,371,746 [9], describes methods for linearizing 2DCTs by controlling the edge resistance structure of the elements.

Talmage in US 4,822,957 [10] describes an edge pattern similar to Pepper's in combination with a 2DRT element and a pick-off sheet. Numerous other such patents have been published, using various approaches, and this area remains fertile ground for new patents to this day. These methods have been found to be difficult to develop and reproduce, and they are susceptible to errors caused by differential heating as well as production problems. Very small amounts of local error or drift can cause considerable changes in coordinate response. The low resistance of the patterned edge strips causes problems for the driver circuit, forcing the driver circuit to consume more power, much more expensive than other measures. There are many patents that reference Pepper's patents, and these patents claim to do similar things. The improvement given by Pepper et al. is not necessarily much better than that of Becker, because at least Becker's scheme is easier and more reproducible for production.

Edge resistance with wire elements: Kable in US 4,678,869 [11] discloses a 2-dimensional array for stylus input using resistive voltage-dividing chains in two axes to which highly conductive electrodes are connected , the electrodes used for detection have some uninteded resistance, and the detection signal is interpolated according to the signal generated between two adjacent electrodes. Unintentional resistance causes a small amount of pincushion distortion in the response. The patent also describes an algorithmic measure to compensate for the slight pincushion distortion caused by this technique. The Kable method doesn't work unless with a stylus attached, i.e. it doesn't describe responding to a human finger. Kable's patent requires a jumper between conductors, thus requiring at least three structural layers (conductor layer, insulation layer, conductor layer).

Multiple Active Edge Electrodes: Turner in US 3,699,439 [12] discloses a uniform resistive screen with active probes having multiple electrode connections on all four sides to linearize the results.

Yoshikawa et al. in US 4,680,430 [13] and Wolfe in US 5,438,168 [14] propose the use of multiple electrode points on each side (opposite the corners) in order to facilitate The interaction of the electric current with the electrodes on other axes reduces pincushion distortion. Although the element is a simple sheet resistor, this measure involves a large number of active electronic connections (such as a linear array of diodes or MOSFETs) in very close proximity to each connection point of the element.

Nakamura in US 4,649,232 [15] is similar to that of Yoshikawa and Wolfe, but with a resistive sensing stylus.

Sequentially scanned strip elements: Greanias et al. in US 4,686,332 [16] and US 5,149,919 [17], Boie et al. in US 5,463,388 [18] and Landmeier in US 5,381,160 [19] along X and Y A method in which the axes are sensed by elements with conductors that are alternately independently driven and sensed, whereby the location of a finger contact or contact with a sensing device or stylus is interpreted. This construction involves multiple layers of materials and special handling. Greanias proposed to use interpolation between the strips to obtain higher resolution in both axes. Both of these require three or more layers to allow for the jumping of conductors within the component. Both of these rely on the measurement of the capacitance of each strip, not on the amount of cross-coupling from one strip to another. Boie also proposes a special protective surface.

Binstead in US 5,844,506 [20] and US 6,137,427 [21] proposes a touch screen using discrete thin wires in a similar manner to that proposed by Kable, Allen, Gerpheide and Greanias. Binstead uses very thin row and column wires to achieve transparency. This patent also proposes using the Greanias method of interpolating between electrode leads to achieve higher resolution. Scanning relies on the measurement of each strip's capacitance to ground, not on the amount of cross-coupling from one strip to another.

Evans also described in US 4,733,222 [22] a system that sequentially drives the bars along the X and Y axes, this system also uses an external capacitor array to derive the sensing signal through the capacitor voltage divider effect. Use interpolation to achieve higher resolution than can be achieved with striping alone.

Volpe in US 3,921,166 [23] describes a discrete-key mechanical keyboard using a capacitive scanning method. There are input rows that are driven sequentially and columns that are sensed sequentially. Pressing a key increases the coupling from row to column, allowing n-key rollover; no interpolation is required. Although not 2DCT, Volpe heralds scanned strip element 2DCT technology. The applicant's own US 6,452,514 [24] also belongs to this type of sensor.

Itaya in US 5,181,030 [25] discloses a 2DRT with resistive strips that are coupled under pressure to a resistive surface at the position of the readout contacts. These strips, or faces, have a one-dimensional voltage gradient applied across them so that the location of a contact point on a particular strip can be easily identified. Each strip requires at least one electrode connection dedicated to it.

Strip elements being cyclically scanned: Gerpheide et al. in US 5,305,017 [26] proposed a computer pointer based on contact pad capacitance, which uses a plurality of overlapping metal strips separated by insulating layers. Orthogonal array. The scan lines are arranged in a cyclically repeating pattern to minimize driver circuit requirements. The cyclic nature of the inventive wiring prevents the use of such a 2DCT for absolute position positioning. The invention is suitable for use in place of a mouse where no actual position determination is required but relative motion sensing is important. Gerpheide proposes a method of signal equalization between two signals of opposite phase at the contact location.

Stripe element read in parallel: Allen et al. in US 5,914,465 [27] propose an element with scanning stripes of rows and columns read out in parallel by an analog circuit. The patent claims lower noise and faster response times than sequentially scanned elements. This approach is great for replacing a mouse's touchpad, but isn't great for larger sizes. As is the case with all strip element 2DCTs, multiple structural layers are required. Allen's method requires large scale integration and a large number of connecting leads. It uses interpolation to achieve higher resolution than achievable with these numbers of raw strips.

In WO 04/040240 [28] "Charge Transfer Capacitive Position Sensor (ChargeTransfer Capacitive Position Sensor)", Philipp described a method of making a touch screen using some individual resistive 1-dimensional strips with reference to Figure 12. The strips can be read in parallel or sequentially because the connections to the strips are independent of each other. Furthermore, interpolated coupling between adjacent lumped electrode elements and objects such as fingers is also described in connection with FIG. 6 . WO 04/040240 [28] is hereby incorporated by reference.

In WO 2005/020056 [29] Philipp describes a position sensor having first and second resistive bus bars separated by a non-uniform conductive region between them (See Figure 3 of the application). Current induced due to contact or proximity in the non-uniform conduction region preferentially flows to the bus bar to be detected by the detection circuit. Since induced currents, such as those induced by drive circuits, preferentially flow in one direction, pincushion distortion in position estimation is largely confined to this single direction. Such 1-D distortions can be corrected very simply by applying a scalar correction factor, avoiding the need for complex vector corrections. This provides a 2D pattern of conductive material for sensing capacitance behind a plastic or glass panel or other medium, which can be used as 2DxT, either in the form of a touch screen or as a 'touch pad'. The conductors may be clear, eg formed of indium tin oxide (ITO), to provide a suitable transparent cover for the display or other backside.

This measure works well for relatively small screens up to about 2 inches (50mm) diagonal for a cell phone, but for larger screens such as those required by some white goods (e.g. microwave ovens), performance will be reduced. Also, with this design, the finger shadow effect can create some problems.

In US 6,288,707 [30] Philipp describes a capacitive position sensor to be used as part of a computer pointing device, using ratiometric capacitive sensing technology. An array of patterned metal electrodes is disposed on the insulating substrate layer, wherein the geometry of the electrodes is selected to produce a varying capacitive output as a user's finger is moved across the electrode array.

Figure 1 of the accompanying drawings reproduces Figure 4 of US 6,288,707 [30]. An array of patterned metal electrodes is disposed on the insulating layer, where the geometry of the electrodes is selected to produce a varying capacitive output as a user's finger is moved across the electrode array. This arrangement includes four interspersed sets of electrodes, two for each dimension. The x-axis groups are triangular, which is easy to see and understand. The first set of deltas 1 are all electrically connected together to an output bus labeled X1. A second group of 2 is also connected together on the output bus labeled X2. The position of the user's hand relative to the x-axis can be determined from the ratio of the signals from X1 and X2. Since capacitance is directly proportional to surface area, and since the pieces connected to X1 together have a larger surface area on the left side than the pieces connected to X2 (and vice versa), only a sufficiently large finger area Being over the pattern at a close enough distance to provide sufficient signal strength ensures the ability to achieve the ratio X1/X2 or X2/X1. The slices of the corresponding groups are connected to the Y1 and Y2 buses. The Y-linked group is also ratiometric, although in a different manner than the X-group. The Y group consists of alternating Y1-connected and Y2-connected rectangular strips, labeled 3 and 4 respectively, with a y-axis dimension that varies with location in such a way as to produce a surface between Y1 and Y2 that varies smoothly with location Y area ratio. Make the sum of each pair of adjacent y-axis strips 3 and 4 constant such that for any two pairs of strips, the sum of the capacitances is the same, i.e. for each pair of strips there is C(Y1)+C(Y2) =C(Y). Then, as the user's finger moves along the y-axis, the detected capacitance ratio is measured in the same way as the C(X1)/C(X2) ratio, ie the largest value becomes the numerator of the fraction.

However, this design provides only limited capability for the 2DCT dimension in the x-direction.

Numerical Methods

Nakamura in US 4,650,926 [31] describes a system for correcting raw 2-dimensional coordinate data using a look-up table system to numerically correct electronic graphics systems such as graphics input cards.

Drum in US 5,101,081 [32] describes a system for numerical correction of electronic graphics systems such as graphics input cards by remote control.

McDermott in US 5,157,227 [33] proposed a numerical method for correcting 2DxT using stored constants that are used during operation to control one or more polynomials to correct the position of contacts reported by segment or quadrant.

Babb et. segments and are based on individual units in order to correct for even small process variations. The methods disclosed by Babb are complex, involving "80 coefficients" and fourth-order polynomials, the coefficients of which must be determined through a rigorous and time-consuming calibration process. In tests conducted by the inventors of the present invention, it has been found that in normal use a 6th order polynomial is required to obtain acceptable accuracy, and the results are still very susceptible to very slight follow-up after calibration due to, for example, thermal drift. impact of change. In particular, corner connections have been found to be the largest contributors to long-term coordinate fluctuations, since these corner connections act as singularities with high gain factors in terms of connection size and quality. Furthermore, this method of numerical correction requires high-resolution digital conversion in order to produce even the most modest resolution output. For example, it has been found that a 14 bit ADC is required to provide a coordinate result of 9 bit quality. The additional cost and power required of the amplifier system and ADC may not be tolerated in many applications.

question

Although extensive previous work has been done in this area, there is still a need to develop low-cost, single-layer, large-area, transparent, low-distortion 2DCTs with a relatively small number of external connections.

Contents of the invention

The present invention provides a two-dimensional position sensor comprising a substrate having a sensing region consisting of electrodes comprising electrodes for determining x-position and electrodes for determining y-position A pattern is defined, wherein the x-electrodes and y-electrodes generally extend along the x-direction and are staggered in the y-direction, and wherein the x-electrodes comprise first, second and third sets of elements formed such that the first and second sets Adjacent elements of the elements of the group are coextensive in the x direction on one part of the sensing area, while adjacent elements of the elements of the second and third groups are coextensive in the x direction on another part of the sensing area, so that the x electrodes provide Corresponding ratiometric capacitive signals across the sensing region in the x-direction.

The x-electrode may also comprise a fourth set of elements, with adjacent elements of the third and fourth set of elements being coextensive within a further portion of the sensing region such that the x-electrode provides a corresponding ratio across the sensing region in the x-direction. capacitive signal.

This principle can be extended to add fifth and further sets of x-electrodes. Topologically, this principle can be extended infinitely. However, in reality, the thickness of the electrode feeder at the peripheral edge of the sensing area for external connection will become thinner and thinner, so to a certain extent, taking into account the limitations of noise and other related factors, adding an x-electrode group becomes not realistic.

In various embodiments of the present invention, a plurality of external wires connected to the electrodes at the periphery of the sensing region are configured, these external wires include: corresponding wires connected to elements of each x-electrode group; and Multiple wire lines connected to the y-electrodes.

In one set of embodiments, a central spine extending in the y-direction from the periphery of the sensing region is configured to interconnect elements of a third set of x-electrodes extending from both sides of the spine, thereby allowing a third Elements of the set of x-electrodes can be contacted from outside the periphery of the sensing region.

Preferably, the spine extends continuously from top to bottom across the sensing area, in which case a single external contact disposed uppermost or lowermost in the sensing area will suffice. Alternatively, the spine could be split, in which case two external contacts would be required on the periphery of the sensing area, one at the top and one at the bottom of the sensing area.

When configured with a mid-spine, corresponding y-electrodes at the same height (ie, same y-position) on both sides of the mid-spine can be connected together to save the use of additional external connection lines. For example, a single external connection line may be connected to the y-electrodes on either side of the spine through conductive traces arranged around the periphery of the sensing region.

In embodiments having a central ridge, a plurality of external wires may be used to connect to the electrodes at the periphery of the sensing region, these external wires including: wires connected to the middle ridge and thus in contact with the third set of x-electrodes, The middle ridge symbolically divides the sensing area into left and right sides; wire routing to elements in the first set of x-electrodes on the left side of the middle ridge; connection to elements in the first set of x-electrodes on the right side of the middle ridge The wire line connected to the element on the side; the wire line connected to the element on the left side of the mid-ridge in the second set of x-electrodes; the wire line connected to the element on the right side of the mid-ridge in the second set of x-electrodes; and a plurality of wire lines connected to the y electrodes.

The x-electrodes can be configured in a variety of topologies to provide coextensibility.

For example, the coextensive elements of respective x-electrode sets may have complementary tapers over their coextensive distance to provide a ratiometric capacitive signal. Alternatively, the coextensive elements of the respective x-electrode sets have adjacent patches of varying area over their coextensive distance in the x-direction to provide a ratiometric capacitive signal.

For example, with reference to an embodiment having a central ridge and first, second, and third sets of x-electrodes, the first and third elements may be tapered toward or from the periphery and the central ridge, respectively, while the second element has a Double-sided bevel that complements the bevel of the third element. As an alternative, in different implementations of the same embodiment, the first and third elements may take the form of interconnected blocks with areas decreasing towards or from the periphery and the spine, respectively, while the second element has a Blocks of varying area complementary to the blocks of the first and third elements.

The y-electrodes are connected individually and/or in groups to respective external electrical lines in order to provide positional information in the y-direction. This is a simple and reliable approach, where the y-position information is simply inferred from the line on which the signal appears. Also, if a significant signal is present on more than one wire line, interpolation or some other approximation can be used. Typically, there will not be enough external lines to have one external line for each y-electrode. Therefore, adjacent y-electrodes must be grouped together, for example using conductive metal traces leading to external wiring. For example, the y-electrodes can be grouped into two, three or four.

The y-electrodes may be interconnected by resistive elements such that a ratiometric capacitive signal is output through external wirelines connected to a subset of the y-electrodes to provide positional information in the y-direction. In this implementation, the y-electrodes are connected to form a so called "slider" as disclosed in WO 2004/040240 [28]. Specifically, the portion of the resistive strip overlying the y-electrode is short-circuited due to being in parallel with the conductive electrode, while the portion extending between adjacent y-electrodes provides a resistive interconnection, as described in WO 2004/040240[ 28] is shown in Figure 6a. The ratiometric signal can then be picked off with a minimum of two external lines at each end of the slider (one connected to the uppermost y-electrode and one connected to the lowermost y-electrode). Higher accuracy can be obtained by adding intermediate sensing (ie, adding one or more additional external lines to the intermediate y-electrodes). This approach is quite flexible, since the number of external lines generally available is limited and restricted, a typical number being 11. If the slider approach is used, once the requisite number of external lines are allocated to connect the x-electrodes, the remaining available external lines can all be used for the y-electrode connections.

The y-electrodes may be arranged in vertically adjacent groups of at least two y-electrodes, the y-electrodes of each group having different vertical widths such that the ratiometric output is output via external wires connected to the different y-electrodes of each group. capacitive signal, thus providing positional information in the y direction. Preferably, the y-electrodes of each group are directly vertically adjacent, ie no x-electrodes are sandwiched between them. However, if the x-electrodes have a smaller width in the y-direction than a finger or other desired implement, the y-electrode set can have interposed x-electrodes. This ratiometric approach based on different vertical widths of the y-electrodes is disclosed in US 6,288,707 [30], in particular the Figure 4 embodiment therein.

The electrodes may be formed of a transparent material such as indium tin oxide (ITO) or any other suitable material. The substrate can also be formed of a transparent material such as glass or a transparent plastic material, e.g., plexiglass (polymethyl methacrylate, PMMA) such as Perspex, or a plexiglass such as Zeonor(TM) or Topas(TM) class of cycloolefin copolymers (COP). However, in some applications there are cases where the electrodes and/or the substrate are not transparent.

It should be understood that the x and y directions are defined by an appropriate coordinate system, most commonly a Cartesian coordinate system in which the x and y directions are orthogonal, although the x and y directions may also be at non-orthogonal angles. In addition, the x and y directions are sometimes referred to below as horizontal and vertical directions, respectively, for convenience, although of course this does not imply alignment with a specific real space such as the direction of gravity.

Description of drawings

In order to better understand the present invention and explain how it can be implemented, the accompanying drawings are illustrated below, in which:

FIG. 1 is a schematic plan view showing an electrode pattern of a related art 2DCT.

2 is a schematic plan view showing some parts of an electrode pattern of a 2DCT of the first embodiment of the present invention.

3 is a plan view of a 2DCT prototype according to the first embodiment, showing an electrode pattern and a first connection layer connected to a y-electrode at the periphery of the electrode pattern region.

4 is a plan view of the 2DCT prototype of FIG. 3, showing electrode patterns and a second connection layer connected to the x electrodes at the periphery of the electrode pattern area, and the second connection layer also connects the external feed lines of the y electrodes to those shown in FIG. connected to the y electrode shown.

FIG. 5 is a system-level schematic diagram of the driving and data acquisition circuits of the first embodiment.

6 is a schematic plan view showing some parts of electrode patterns and y-connections of a 2DCT of a second embodiment of the present invention.

7 is a schematic plan view similar to FIG. 6 of some parts showing electrode patterns and y-connections of a modification of the second embodiment.

8 is a plan view of a prototype of a 2DCT according to a second embodiment, showing an electrode pattern and a first connection layer connected to a y-electrode at the periphery of the electrode pattern region.

Fig. 9 is a plan view of a 2DCT prototype according to a second embodiment, showing the resistive layer connecting the resistive element between the y-electrodes.

Figure 10 is a plan view of the 2DCT prototype of Figure 8, showing the electrode pattern and the second connection layer connected to the x-electrode at the periphery of the electrode pattern area, the second connection layer also connects the y-electrode external feed line to the electrode pattern shown in Figure 8 The y electrode is connected.

Fig. 11 is a schematic plan view showing a part of electrode patterns of the third embodiment.

12 is a plan view showing electrode patterns of the 2DCT prototype according to the third embodiment.

Fig. 13 is a schematic plan view showing some parts of an electrode pattern of a fourth embodiment.

Fig. 14 is a schematic plan view showing some parts of an electrode pattern of a fifth embodiment.

Fig. 15 is a schematic plan view showing some parts of an electrode pattern of a sixth embodiment. as well as

Figure 16 is a schematic plan view of a glass touch panel incorporating a 2DCT embodying the present invention.

Detailed ways

2 is a schematic plan view showing a representative portion of an electrode pattern of the 2DCT of the first embodiment, wherein the electrode pattern defines a sensing region of the device. These electrodes are arranged on a substrate which is not explicitly shown but has an upper surface lying in the plane of the drawing. The substrate may suitably be a flexible transparent plastics material such as polyethylene terephthalate (PET). The substrate is usually insulating. The electrode patterns are formed with indium tin oxide (ITO) having a resistivity of several hundred ohms/square. This is a transparent material, so it is suitable for display applications or other applications where buttons or other stencils underneath need to be visible.

In general, electrode patterns can be formed by depositing or removing any suitable conductive material. Deposition can be, for example, by vapor deposition or screen printing. Removal can be, for example, by laser or chemical etching.

The electrode pattern defines y-electrodes 10, 12 for determining y-position and x-electrodes 14, 16, 18, 20, 22, 24 for determining x-position. As shown, the x-electrodes and y-electrodes generally extend in the x-direction, but are staggered in the y-direction. The y-electrodes 10, 12 are in the shape of simple straight bars, ie, elongated rectangles, while the x-electrodes 14-24 have the shape of tapered triangles.

The x-electrodes are first described in more detail, followed by the y-electrodes.

The X electrodes can be divided into three groups. The first group is triangular beveled electrodes 14, 24 arranged on the left and right sides of the sensing area. The second group is double-sided beveled triangular electrodes 16, 22 arranged to extend inwardly from the left and right sides of the sensing area, respectively, towards the center. A third set of x-electrodes 18, 20 extend outwardly from an integrally formed central spine 26 towards the left and right, respectively. Adjacent elements 14, 16 and 24, 22 of the elements of the first and second groups are co-extensive in the outer portions I and IV of the sensing area respectively towards the left and right sides of the sensing area along the x-direction. Adjacent elements 16, 18 and 22, 20 of the elements of the second and third groups are coextensive in the x-direction respectively within inner portions II and III of the sensing area on either side of the central spine.

In this way, each pair of adjacent coextensive first and second sets of x-electrodes or second and third sets of x-electrodes each forms a so-called slider as described in Ref. [28] . Specifically, the sliding part is of the type shown in Fig. 15 of reference [28], and the relevant content in reference [28] describing the operation of such a sliding part is hereby incorporated by reference . It should be understood that the shape and size of these electrode elements are appropriately designed relative to the actuator (typically a human finger) to provide a finite element across their coextensive (i.e., overlapping in the x-direction) length. Ratiometric capacitive signals.

The x-electrodes 16 that are beveled on both sides on the left side are commonly connected to the external connection line X1 through conductive lines 30 arranged along the y-direction at the left periphery of the sensing region close to the left edge of the x-electrodes 16 . Note that the double-sided beveled electrodes have pad areas 33 at their left ends to facilitate such external connections.

The x-electrode 14 that is beveled on the left side is connected to the external connection line X2 through the conductive line 32 arranged along the y-direction near the left edge of the x-electrode 14 on the left periphery of the sensing area.

The tapered x-electrodes 18 and 20 protruding from the central ridge 26 are of course commonly connected by the central ridge 26 and have electrical contact with the periphery of the sensing region through the central ridge 26 . The external connection line X3 is connected to the spine by a wire line 34 in contact with the base of the spine 26 .

The right-side beveled x-electrode 24 is commonly connected to an external connection line X4 in a similar manner to the corresponding left-hand x-electrode 14 via a conductive line 36 arranged in the y-direction at the right periphery of the sensing region near the right edge of the x-electrode 24 superior.

The right double-sided beveled x-electrode 22 is aided in a similar manner to the corresponding left-hand x-electrode 16 by means of an enlarged The pad area 39 is commonly connected to the external connection line X5.

In this way, the x-electrodes 14-24 are in external contact with the five external connection lines X1-X5 for readout.

The y-electrodes are divided into two groups 10 and 12 to the left and right of the central spine 26, respectively. As already mentioned, they have a simple straight bar shape and are arranged between each adjacent set of x-electrodes 14, 16, 18 on the left and between each adjacent set of x-electrodes 20, 22, 24 on the right. between. The y-electrodes 10 and 12 are connected in vertically adjacent groups by conductive lines, so that the y-resolution of the sensing area is limited in this embodiment to the vertical distance corresponding to the vertical extent of these interconnected y-electrodes. Grouping the y electrodes together in this way reduces the y resolution, but reduces the number of external connection lines required for the y electrodes. In the example shown, the lowermost set of y-electrodes comprises four pairs of y-electrodes which are connected together to a conductive track 50 which forms part of the external connection line Y1. Although not explicitly shown in the figure, each pair of y-electrodes at the same height is commonly connected by a peripheral trace. The upper group includes three pairs of y electrodes, although only the first pair is shown, which are connected to track 52 for connection to external line Y2. A total of seven sets of y electrodes are connected to respective external lines Y1-Y7 by associated conductive traces. In this embodiment, the y-values are derived from these 7 externally connected lines, which provide only 7 units of y-resolution for simple control algorithms, although by passing between adjacent y-lines Doing interpolation allows for possible additional y resolution.

In summary, this 2DCT provides quasi-continuous x-resolution through sliding sections arranged in four footprints I–IV across the width of the sensing region along the x-direction, combined to form vertically adjacent 3, A set of 4 horizontally extending electrode strips provides a stepped y-resolution. A total of 12 external connection lines are used, 5 for X and 7 for Y.

The combination of the central ridge and the beveled electrodes on both sides allows the sensing area to have a large extent in the x-direction to provide a large sensing area that can be made transparent without external connections other than the periphery. Furthermore, this electrode pattern design means that finger shadowing effects are insignificant, since any centroid shift of the capacitive signal due to the physical position of the finger is limited by the lateral extension of the electrodes. For example, with this design, a device can be fabricated with a sensing area that is 6 inches (150 mm) diagonal.

3 is a 1:1 scale (ie actual size) plan view of the 2DCT prototype designed according to the first embodiment, showing the electrode pattern and the first connection layer connected to the y-electrode at the periphery of the electrode pattern area. For ease of reference, the area covered by the previous schematic is shown with a dashed rectangle at the bottom of this figure. The outlines of the fingers are also shown roughly to scale.

Obviously, the electrode pattern of ITO usually covers the main part of the substrate 40 . In this example, the pattern covers a rectangular area that matches the area where the touch screen or other device needs to form the sensing portion. Also marked are the four footprints I-IV of the x-electrodes described previously. The generally rectangular substrate 40 also has a neck 42 projecting halfway from the left side of the substrate. Neck 42 is used for external contact, as will be explained in conjunction with the next figure. On the left side of the substrate 40, that is, the side adjacent to the neck protrusion 42, it can be seen that there are 7 groups of conductive traces 50-62, which form the external connection lines Y1-Y7 of the y electrodes, and the lines Y2-Y7 pass through the rails. Lines 52-62 each connect to three y-electrodes, while Y1 connects to four y-electrodes through trace 50, for a total of 22 y-electrodes in this left half of the device (ie, the left half of spine 26). On the right side, there are 22 y-electrodes arranged in exactly the same way, except for the four at the bottom, which are connected in groups, they are all connected in groups of three. The traces 50-62 of the external connection lines Y1-Y7 on the right side of the substrate pass around the top of the substrate to the left side of the substrate, so that the corresponding y-electrode pairs on the left and right sides and the commonly connected y-electrode pairs groups are joined by a single conductive trace wire.

Figure 4 is a plan view of the 2DCT prototype of Figure 3, showing electrode patterns and a second connection layer connected to the x electrodes at the periphery of the electrode pattern area, the second connection layer also connects the external feed lines of the y electrodes to those shown in Figure 3 The y electrodes are connected to each other. An insulating layer is inserted between the first and second layers shown in FIGS. 3 and 4 to provide an insulating region preventing electrical contact between portions of the first and second connection layers and to ensure An open area of electrical contact between other parts of two connecting layers.

First, the case of y-electrode connection will be described. The seven conductive traces 44 extend in parallel along the upper part of the neck protrusion 42 to the left part of the main area of the substrate 40 in the x direction. They then spread out and terminate with enlarged contact pads 46 directly over a portion of traces 50-62 for each y-electrode connection Y1-Y7 within the first connection layer of FIG. Signals for each y-electrode group can be fed in and out via external contact tracks 44 . There is an open area at each contact pad 46 in the insulating layer to ensure that each of the Y1-Y7 traces 44 on the second connection layer is compatible with the Y1-Y7 wire traces 50-62 in the first connection layer. electrical contact between each of the There is also an insulating region within the insulating layer covering each of the Y1-Y7 tracks contacting the y-electrodes on the left and right sides of the substrate above the ITO pattern.

Next, the case where the x electrodes are connected will be described. The 5 wire lines 30-38 for the external connections X1-X5 have already been described in connection with FIG. 2 and can be seen in the second connection layer of the prototype in FIG. 5 . As can be seen, the x-electrode connections are provided entirely on the second connection layer, unlike the y-electrode connections which are distributed between the first and second connection layers. That is, traces 30-38 run around the bottom of substrate 40 and then merge into five parallel traces leading to neck 42 where they meet seven parallel y-electrode wires. It is to be noted that the x-electrode connection traces and pads arranged vertically over each side of the ITO region contacting the x-electrodes are isolated from the y-electrode connection traces by an insulating layer.

FIG. 5 is a system-level schematic diagram of a multi-channel sensor circuit 140 used with the touch screen of the first embodiment. In this figure, the sensor circuit 140 is depicted as having 5 capacitive electrode inputs X1, X2, X3, X4, X5 from the x-electrodes, and a single capacitive electrode input Yn representing the 7 y-electrode inputs. In practice, there will be 7 of these wires, one for each y-electrode input, giving a total of 12 wires required. Charge control circuit 157 charges all capacitive inputs X1-X5 and Y1-Y7 simultaneously using charge switch 156 connected to reference voltage line 158 .

In one variation, the charging control line 157 is omitted and the charging switch 156 is replaced with a pull-up resistor constantly connecting each electrode to a voltage source. The resistance value of the pull-up resistor is chosen such that the RC time constant is greater than the discharge interval used to discharge the layer to the charge detector array. This resistance value can be, for example, between 15 kΩ and 25 kΩ.

Channels X1-X5 and Y1-Y7 act simultaneously in delivering charge to the charge detector, as shown, by using a single discharge control line 163 to drive discharge switch 162 to discharge all charged electrodes. Following a charge transfer or series of charge transfers, the analog multiplexer 182, under the control of the microprocessor 168, selects which of the capacitor outputs of the charge detector is to be fed to the amplifier 184 and ADC 186, thereby feeding to an external control and data acquisition circuit, typically a PC. In addition, reset switch array 188, controlled by reset control line 190, is activated after each pulse or train of pulses, resetting the capacitive input to a known reference value (eg, to ground). It will be apparent to those skilled in the art that many circuit elements of each channel sensor have been omitted from the figures for clarity. As far as the x-channels X1-X5 are concerned, these channels need to be driven and the signals need to be processed to take into account the The "slider" approach requires ratiometric information derived from these signals. More details on sensor circuits and methods of driving sensor circuits with pulse trains can be found in prior art patent publications by Harald Philipp, such as references [28], [30] and [34].

In general terms corresponding to the first embodiment, it can now be seen that this design has a centrosymmetric electrode pattern with a central ridge dividing the sensor area into two halves, left and right. The central ridge forms the "trunk" form of the "Christmas tree", the "branches" of the tree are the single-sided beveled electrodes protruding from the sides of the trunk, and the second of the two sets of bilateral beveled electrodes that circumscribe the sides of the sensor area. The beveled portions are coextensive, whereas this double-sided beveled first beveled portion is coextensive with two other single-sided beveled electrode sets also circumscribing the sensor area side. These electrodes are all used for sensing in the horizontal direction and they are vertically interleaved with strips that circumscribe the sides of the sensor area and form the vertical position sensing electrodes. The sensing area is operated with 12 external connections, 5 for horizontal sensing, connected to each set of beveled electrodes, and 7 for the 22 vertical electrode rows, this reduction is achieved by connecting adjacent 3 Or vertically adjacent groups of 4 vertical electrode rows are commonly connected, thereby reducing the total number of external connections at the expense of vertical resolution. In addition, it is shown how the structure has 4 layers, two layers for connections, an insulating layer to control the connection between the two connection layers, and an electrode pattern that can be omitted and formed directly on one of the connection layers layer.

Next, a second embodiment of the present invention will be described. In most respects, the second embodiment is identical to the first embodiment. Use the same ITO electrode pattern. In addition, the external connections of the x electrodes are identical, so the electrode pattern layer and the first conductive layer are identical. The difference between the second embodiment and the first embodiment is the y sensing. In a first embodiment, the electrode strips provide discrete y-position information, where the resolution is defined by the vertical spacing of the y-electrode strips, or in the case of multiple adjacent y-electrode strips being commonly connected to reduce external connection lines. The rate is defined by the vertical spacing of groups of commonly connected y-electrode strips. In the second embodiment, the same y-electrode arrangement is used, i.e. the horizontal strips are interleaved between the x-electrodes, but the y-electrode strips are resistively connected to each other in a so-called "slider" The quasi-continuous position information in the vertical direction can be obtained by using an external measuring circuit.

6 is a schematic plan view showing a part of electrode patterns and y-connections of a 2DCT of a second embodiment of the present invention. A human finger is also shown roughly to scale. For clarity, the x-electrodes and their external connection traces are omitted. The figure shows the middle part of the left half of the sensing area with several vertically offset y-electrode strips 10 (thirteen are illustrated in the figure) similar to the first embodiment. Each strip is connected to vertically adjacent strips by conductive or metal lines 70 with discrete resistors 72 connected in series. The y electrode strips 10 are externally connected by conductive traces leading to external connection lines for Y sensing. Four such external connection lines 54'-60' are shown connected to every third or fourth y-electrode.

Electrically, the resistors 72 and their interconnecting lines 70 provide a resistive path between adjacent y-electrode strips 10, which resistive path between vertically adjacent conductive external connection lines 54' and 56', 56 ' and 58' and so on. (In the case of any pair of adjacent lines (such as 54' and 56'), this is electrically the same as the slide of the embodiment shown in Fig. 6a in Ref. [28].) As in Ref. As described in [28], the y-position is detected using a ratiometric analysis, for example using a measuring circuit as described in Ref. [28] or other measuring circuits known in the art for this purpose.

Normally, a minimum of two such external connection wires are necessary in the second embodiment to form the end connections of the slider. These end connections should preferably be connected to the uppermost and lowermost y-electrodes, or at least to the y-electrodes in the immediate vicinity above and below. It is also beneficial to have one or more additional external connections between these two end connections to improve y-position sensing accuracy by effectively creating multiple slides in the y-direction. Usually for reasons of cost it is desirable to limit the external connections to a fixed number, in this case since many external connections for the y-electrodes can be provided, the number can correspond to the number of free ones after allocating enough lines for the x-electrodes external connection.

Fig. 7 is a schematic plan view similar to Fig. 6, showing some parts of electrode patterns and y-connecting lines of a modification of the second embodiment. The y-electrode strip 10 and the external connection lines 52'-60' perform the same functions as explained in connection with FIG. In this variant, instead of using discrete resistors to connect vertically adjacent y-electrodes, a resistive strip 74 of uniform resistance per unit length (in the y-direction) is arranged vertically above each y-electrode strip. Since these electrode strips are essentially metallic, i.e. conductive, the portions of the resistive strips that overlay the y-electrode are electrically ineffective, since these portions are effectively in parallel with the y-electrode when viewed from the vertical direction, thus is shorted out. The portion of the resistive strip between the y-electrode strips thus forms a resistive path between the y-electrodes in the same manner as the discrete resistors of FIG. 6 . The resistive strip 74 is made of a high resistance film, such as a carbon based thick film.

8 is a plan view of a 2DCT prototype designed according to the second embodiment, showing an electrode pattern and a first connection layer connected to a y-electrode at the periphery of the electrode pattern area. FIG. 8 is comparable to FIG. 3 of the first embodiment. Basically, the substrate 40 with the neck protrusion 42 carries the same structure, the only difference is that every third or fourth y-electrode is connected to the external connection lines 50'-60' and the first embodiment is omitted. common connection. The exceptions are the bottom two y-electrodes, which are commonly connected to electrical track 50'. Furthermore, it is to be noted that the y-electrodes are provided with a total of 6 external connection lines Y1-Y6 instead of 7.

Fig. 9 is a plan view of a 2DCT prototype designed according to the second embodiment, showing the resistive layer connecting the resistive elements between the y-electrodes. This layer is specific to the second embodiment and provides a resistive path 74 extending vertically over the ends of the outer ends of the y-electrode strips on each side of the sensing region. Each vertically extending resistive via 74 is formed from a single trace of a material of suitable resistivity. It is to be noted that this layer is also partially covered with a highly resistive material 75 (shaded gray) which covers the peripheral parts of the substrate and the part of the neck adjoining the main body of the substrate. The resistive material terminates in a walled or saw-toothed shape 74 that alternates back and forth across the associated resistive material via 75 such that the resistive via 75 is directly connected to the outer end portion of each y-electrode strip, but It is covered at the end where it straddles the x-electrodes, preventing unwanted electrical interference with the x-electrodes. An alternative is to have a meandering pathway 74, for example following a rampart or zigzag pathway, to avoid crossing the ends of the x-electrodes.

Fig. 10 is a plan view of the 2DCT prototype of Fig. 8, showing the electrode pattern and the second connection layer, the second connection layer provides the connection with the x-electrodes and connects the y-electrodes to the external feed line shown in Fig. 8 at the periphery of the electrode pattern area. The connection on the y-electrode connecting line. This is almost identical to Figure 4 of the first embodiment, except that there are fewer Y lines. That is, the x-electrode external connections X1-X5 and associated traces 30-38 are identical, while the Y external connections Y1-Y6 that protrude from the neck 42 to connect to the matching traces of the first connection layer are identical. The same applies to the external connection line 44 (only one is missing in the second embodiment). In addition, the insulating layer has appropriate open regions and insulating regions similar to those in the first embodiment.

The drive and data acquisition circuitry is similar to that described above for the first embodiment, except that in this case "slider" type processing is required for the y electrode signals in addition to the x electrode signals. As already mentioned, suitable circuits can be found in previous patent publications in the name of Harald Philipp, such as ref. [28] and ref. [30] and [34].

FIG. 11 is a schematic plan view showing portions of an electrode pattern of a third embodiment. Unlike the first and second embodiments, the third embodiment has no central spine. Alternatively, the central portion of the sensing area is defined by the coextensive area of electrode sets of double-sided beveled electrodes contacting externally on the left and right sides of the device. It can be seen that, in the absence of a central ridge, the y-electrodes 10 are individual straight bars each extending across from one side of the sensing region to the other. The y-electrode 10 can be contacted only from the left or right, or partly from the left or right, or redundantly from both sides. The x electrodes are arranged between each pair of vertically adjacent y electrodes 10 and consist of four sets of x electrodes 80 , 82 , 84 and 86 . x-electrode sets 80 and 86 are single-sided beveled electrodes extending from the left and right sides of the sensing area, respectively. x-electrode sets 82 and 84 are double-sided beveled electrodes that also extend from the left and right sides of the sensing region, respectively. The sensitive part of the sensing area for x-resolution is formed by three coextensive portions of different x-electrode sets, namely: the left side of the sensing area defined by the co-extensive x-electrode sets 80 and 82 in the x-direction The first part I of the, the second part II in the middle of the sensing area is defined by the double-sided beveled x-electrode sets 82 and 84 co-extensive in the x-direction, and the x-electrode sets 84 and 86 are co-extensive in the x-direction The third part III defined on the right side of the sensing area. In this manner, each adjacent coextensive first and second set of x-electrode pairs, or the second and third set of x-electrode pairs, or the third and fourth set of x-electrode pairs each forms a A so-called slide as described in Ref. [28]. The external connections are similar to the first and second embodiments and are therefore not shown here. However, it should be noted that for the x-electrodes there will need to be 4 external connection lines X1-X4. For the y-electrodes, the same considerations as for the first and second embodiments can be made. In this connection it is pointed out that the addressing of the y-electrode for the third embodiment can follow that of the first or second embodiment.

Fig. 12 is a plan view showing electrode patterns of a 2DCT prototype designed according to the third embodiment. This employs the patterned structure of Figure 12, with 15 rows of x electrode sets and 16 rows of y electrode strips interleaved with the x electrode sets. Note also that the substrate 40 has a neck 42 provided on the bottom side, which is a more convenient assignment for this embodiment. The bottom four y-electrode strips are connected together (following the approach of the first embodiment), while the other y-electrode strips are connected together in groups of three to provide a y-resolution limited to 5 discrete rows, which 5 Rows are connected to external measurement circuits via 5 lines Y1-Y5. The y-resolution can be improved by modifying the prototype to follow the approach of the second embodiment. Each of the 4 x-electrode groups has its own external connection lines X1-X4. There are thus a total of 9 external connection lines. For the sake of simplicity, the other layers of the prototype are not shown for this embodiment, but it should be understood that a generally similar approach to the first and second embodiments can be followed.

FIG. 13 is a schematic plan view showing portions of an electrode pattern of a fourth embodiment. The x electrodes 82, 84, 86, 88 are arranged in the same manner as in the third embodiment to provide three columns of x position sensitive x electrodes covering I, II and III. (In an alternative, the x electrodes may be arranged as in the first and second embodiments.) However, the arrangement of the y electrodes in the fourth embodiment is different from the above embodiments. That is to say, in the fourth embodiment, the y-electrodes follow the ratiometric pair approach of the prior art shown in FIG. 1 of the accompanying drawings, that is, the y-electrode structure shown in FIG. 4 of reference [30].

In this arrangement, for each cell of the electrode pattern, between each adjacent row of x-electrodes 82, 84, 86, 88 there are adjacent independently addressable pairs of different areas. y-electrodes, so that when a user's finger or other implement is adjacent to these y-electrodes, two adjacent independently addressable y-electrodes each provide a corresponding signal whose magnitude is proportional to their relative area. By varying the relative areas of adjacent pairs of independently addressable y-electrode strips within each row, the ratio of these signals can be made to characterize the y-position within each y-electrode cell. In the example shown, each cell has 5 y-electrode rows with area ratios from top to bottom of 1:0, 1:2, 1:1, 2:1, 0:1, where the first value is presented as a signal derived from a first set 90 of commonly connected y-electrodes 92 , 94 , 96 , 98 , while the second value is presented as a signal derived from a second set 100 of commonly connected y-electrodes 102 , 104 , 106 , 108 obtained signal. A value of zero means that the y-electrodes for this row are formed only by y-electrodes from another group, which in this example is the case for the uppermost and lowermost y-electrode rows of each cell. The first group 90 is connected externally to the line Y1 and the second group 100 is connected externally to the line Y2. Each of the other electrode pattern units will require two additional external Y connection wires. For example, in a sensor using the electrode pattern cell shown in Figure 13, if there are 15 rows of y electrodes and 14 rows of x electrodes, there would be 3 cells, requiring 6 Y connections Y1-Y6 and 4 X connections X1- X4, that is, 10 in total.

In principle, any number of y-electrode rows can be grouped into a cell, with two co-addressable groups of y-electrodes. In practice, however, this number will be limited by precision constraints. The number of y electrode rows per unit is at least 3, but can also be 4, 5 (as shown in the figure), 6, 7, 8, 9, 10 or even more rows.

It should be understood that although in the example shown y-electrode pairs are used, in principle 3 or more y-electrodes could be used and their relative areas used to encode position, in which case for a given Noise level, larger cells can be made, ie, cells in which a large number of rows can be addressed by connecting pairs through a single external y-position.

Furthermore, while it is convenient for processing circuitry to produce a ratio of surface areas that varies smoothly with y-position within each cell, as in the example shown, in principle such variation with y should be possible with appropriate processing circuitry. Down can be arbitrary.

The Y group consists of alternating Y1-connected and Y2-connected rectangular strips, labeled 3 and 4, respectively, with a Y-axis width that varies with location in such a way that a smoothly varying Y1-Y2 distance with location Y is produced. ratio of surface area. Make the sum of each pair of adjacent y-axis strips 3 and 4 constant, so for any two pairs of strips, the sum of the capacitances is the same, i.e. for each pair of strips there is C(Y1)+C(Y2) =C(Y). Then, as the user's finger moves along the y-axis, the larger capacitance value becomes the numerator of the fraction.

Fig. 14 is a schematic plan view showing a part of the electrode pattern of the fifth embodiment. This pattern differs here from the previous embodiments in that the double-sided beveled x-electrode 16' is reversed from a "convex" shape to a "concave" shape, with the bevel being tapered toward the middle of the double-sided bevel, rather than from Bevel the middle towards the sides. This double sided tapered shape is shown with reference to an embodiment with a central ridge 26', but it can also be used for designs without a central ridge. The single-sided beveled x-electrodes 14', 18' are correspondingly reversed to form the necessary co-extension with the concave double-sided beveled electrode 16'.

FIG. 15 is a schematic plan view showing portions of an electrode pattern of a sixth embodiment. This embodiment can be understood by comparing with the first embodiment shown in FIG. 2 . As in the first embodiment, the sensing area is divided into left and right halves by a central spine 26". The y-sensing is performed by left and right y-electrode strips 10", 12", which communicate with respective rows of left and right x-electrodes 14", 16", 18" and 20", 22", 24" are interleaved. Note that the same reference numerals are used to designate corresponding electrodes, but with double primes for the sixth embodiment.

Although the overall arrangement of the x and y electrodes is the same as that of the first embodiment, and the shape of the y electrode is also the same, the shape of the x electrode is different. Instead of having a smooth triangular tapered shape, the x-electrodes forming the coextensive region have a saw-tooth shape with x-electrode groups 14" and 16", 16" and 18", 20" and 22", and 22" and 24" The coextensibility of is formed by the interdigitation in the y-direction, such that adjacent blocks resulting from coextensive electrode pairs define an area ratio specific to the x position. From the point of view of the area ratio provided by the interdigitated shape in the y direction, as long as the driving area (such as the finger contact area) has an appropriate size, as shown schematically by the dotted ellipse on the left half of the sensing area in the figure, The desired x-dependent change of the ratiometric signal resulting from the coextensive pair of x electrodes can still be achieved. This interdigitated arrangement may be preferable for sensor areas primarily used for button arrays, as it provides x-position information corresponding to the width of each interdigitated element (shown as "w" in the figure) stepwise change. In this way, the x and y position information can be given a stepped sensitivity which is a preferred implementation for button arrays. In the example shown, it can be seen that there will be 14 steps within the x-position ratiometric signal, 7 steps on either side of the central spine 26".

This embodiment of a stepped sensitivity that symbolically subdivides the sensing area into a rectangular grid in both the horizontal and vertical directions is in contrast to the horizontal and vertical sensitivity provided by the "slider" type configuration of the x and y electrodes. The second or fourth embodiment of the quasi-continuous sensitivity in both directions is opposite.

Figure 16 is a schematic plan view of a glass touch panel device incorporating a 2DCT designed according to any of the above described embodiments of the invention. The previously described 2DCT sensor area carried by the substrate 40 is attached to the underside of a glass panel 116, the glass panel 116 is, for example, 5 mm thick, with a button pattern 110 sandwiched between the underside of the glass panel 116 and the substrate 40 . The button gobo sheet 110 is a printed static piece, but in other cases could use a display that can dynamically change between multiple button patterns and/or have e.g. Instead of a display of continuous features of the bar, it is relevant for the control of the device equipped with this 2DCT. In general, panel 116 need not be glass, but may be any suitable dielectric material. Usually it will be transparent so that it can be integrated with static or dynamic displays. The panel will typically form part of a larger piece of equipment such as the door of a microwave oven, the top panel of a cooker or the cabinet of a hand-held workflow tracking device for on-site use by maintenance personnel.

For example, the button gobo 110 is illustrated to show an array consistent with a 5x6 grid, with a double-sized button in the lower right corner, providing a total of 30-1=29 buttons. External connection lines from the sensor area are provided via neck bump 42 to the measurement circuitry carried by printed circuit board (PCB) 112 . The measurement circuit PCB is attached to the end of the neck 42 and is also fixed under the glass panel 116 . Cable 114 connects the measurement circuitry to other digital electronics and power supplies.

It should be understood that a 2DCT embodying the invention may have many other features. For example, in some applications it is desirable to have a "wake-up" feature whereby the entire device "sleeps" or is placed in some inactive or background state. In such cases, it is often desirable to have functionality that triggers a wake-up signal whenever a body part is within a certain distance. The element can be driven as a single large capacitive electrode regardless of positioning, while the unit is in the background. During this state, the electronic driver logic looks for very small signal changes, not necessarily large enough to be handled as 2D coordinates, but sufficient to determine that an object or person is in the vicinity. The electronics then "wake up" the whole system, the components are driven, and it becomes true 2DCT again.

references

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Claims (12)

1. two-dimensional position sensor, comprise substrate with sensing unit, this sensing unit is used for determining that by comprising the electrode of x position and the pattern of the electrode of the electrode that is used for definite y position limit, wherein x electrode and y electrode are totally along x direction extension and staggered on the y direction, and wherein the x electrode comprises first, second and the 3rd group element, described element forms and makes first and second groups the adjacent elements of element extend jointly in a part of upper edge of sensing unit x direction, and the adjacent elements of second and the 3rd group element extends jointly in another part upper edge of sensing unit x direction, makes the x electrode provide along the corresponding ratio system capacitive signals of x direction across sensing unit.

2. the sensor of claim 1, wherein the x electrode also comprises the 4th group element, the adjacent elements of third and fourth group element extends on the another part of sensing unit jointly, makes the x electrode provide along the corresponding ratio system capacitive signals of x direction across sensing unit.

3. the sensor of claim 2 also is included in many external cable circuits that the periphery of sensing unit is connected with electrode, and these external cable circuits comprise:

Corresponding each electrical wiring that is connected with the element of each x electrode group respectively; And

Many electrical wirings that are connected with the y electrode.

4. the sensor of claim 1 also comprises the median ridge that extends along the y direction from the periphery of sensing unit, the element of the 3rd group of x electrode extending from the both sides of median ridge of being used for interconnecting, thus make the element of the 3rd group of x electrode can be from the peripheral outside contact of sensing unit.

5. the sensor of claim 4 also is included in many external cable circuits that the periphery of sensing unit is connected with electrode, and these external cable circuits comprise:

Thereby be connected the electrical wiring that contacts with the 3rd group of x electrode with median ridge, median ridge symbolically is divided into sensing unit left side and right side;

With the element wire connecting circuit that is in the median ridge left side in first group of x electrode;

With the element wire connecting circuit that is in the median ridge right side in first group of x electrode;

With the element wire connecting circuit that is in the median ridge left side in second group of x electrode;

With the element wire connecting circuit that is in the median ridge right side in second group of x electrode; And

Many electrical wirings that are connected with the y electrode.

6. the sensor of any one claim in the claim 1 to 5, the element of the common extension of wherein corresponding each x electrode group has complementary degree of splaying on their common distances of extending, so that ratio system capacitive signals to be provided.

7. the sensor of any one claim in the claim 1 to 5, wherein corresponding each x electrode group on their common distances of extending, have the adjacent block that area changes at the common element that extends on the x direction, so that ratio system capacitive signals to be provided.

8. the sensor of any one claim in the claim 1 to 5, wherein the y electrode is connected with corresponding external cable circuit individually and/or in groups, thereby is provided at the positional information on the y direction.

9. the sensor of any one claim in the claim 1 to 5, wherein the y electrode is interconnected by resistance element, makes the external cable circuit that is connected by the subclass with the y electrode export ratio system capacitive signals, thereby is provided at the positional information on the y direction.

10. the sensor of any one claim in the claim 1 to 5, wherein the y electrode spread becomes the vertical adjacent group that respectively has at least two y electrodes, the y electrode of each group has different vertical width, make external cable circuit output ratio system capacitive signals, thereby be provided at the positional information on the y direction by connecting with the different y electrode of each group.

11. the sensor of any one claim in the claim 1 to 5, wherein electrode is made with transparent material.

12. the sensor of any one claim in the claim 1 to 5, wherein substrate is made with transparent material.

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