Bipolar Projected Haptics with Balanced Loading

Abstract

The indirect haptic device includes a substrate having an upper surface and a lower surface, and a plurality of haptic electrodes and a plurality of island electrodes disposed on the upper surface. The device further includes a plurality of transmitting electrodes and a plurality of receiving electrodes disposed on the lower surface, a position sensor, and a friction modulator. The device further includes a control device configured to apply bipolar electrical signals to the plurality of transmitting electrodes to detect a touch position of a user's extremity and to modulate friction between the user's extremity and the touch surface. Each of the plurality of haptic electrodes is substantially aligned with and capacitively coupled to a corresponding two of the plurality of transmitting electrodes.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62 / 853,419, filed May 28, 2019, and U.S. Nonprovisional Patent Application No. 16 / 884,932, filed May 27, 2020, the disclosures of which are incorporated herein by reference in their entireties.

[0002] The present invention relates to haptic devices, and more particularly to haptic devices that provide a user with indirect haptic feedback and texture sensations through modulation of friction on a touch surface of the device. [Background technology]

[0003] The technique of electroadhesion is known in the art to modulate the friction between a human finger and a surface to generate indirect haptic effects experienced as the finger slides across the touch surface. The change in friction generated by varying the strength of the electroadhesion effect causes tactile effects that can be experienced as vibrations, textures, edges, surface undulations, and events such as hitting a ball. Electroadhesion is an attractive technique for conveying rich haptic sensations because it does not involve mechanical motion (i.e., it is solid state), uses power efficiently, has high bandwidth, and can be localized to different regions of a surface. It is often desirable to utilize electroadhesion on transparent touch surfaces such as touch screens. In these applications, it is also desirable to have a means of measuring the position of each finger touching the surface. In other words, it is desirable for the surface to function as a touch screen, track pad, or other touch input device while also providing haptic feedback to each fingertip touching the surface.

[0004] Electroadhesion relies on the formation of an electric field acting across the gap that exists between the fingertip and the surface it is touching. The gap exists due to the roughness of the skin (and possibly the surface). That is, true contact occurs at only a few points, while air remains between the two surfaces over the majority of the apparent contact area. In practical applications, other fluids such as water or sebum may also be present. The presence of other fluids does not prevent electroadhesion from occurring. Thus, we use the term "gap" with the understanding that other fluids may partially fill the gap. The electric field in the gap exerts an attractive force between the bound or polarized charges contained in the skin and the surface. This increase in attractive force causes an increase in friction, which is otherwise referred to as friction modulation. For a given system configuration, the strength of the friction modulation effect depends primarily on the strength of the electric field in the gap. In practical devices, it is desirable to use the lowest possible voltage to generate the electric field.

[0005] As a rough guide, experience has shown that the gap between a finger and a lightly textured surface such as anti-glare glass is about 2 microns on average. The maximum electric field that can be sustained in a gap of this size without breakdown is preferably about 1e8V / m, but that value can vary based on various factors, including the size of the gap. At this field strength, the maximum useful voltage is preferably 2e-6m x 1e8V / m = 200V, but that value can also vary based on various factors, including the size of the gap. In practice, a somewhat lower voltage can provide a margin of safety and reliability. For purposes of illustration, we will assume that it is desirable to generate 100V across the gap, but lower or higher voltages may be used.

[0006] 100V is a convenient value because there are many silicon processes that can be used to build integrated circuits for switching voltages up to a few hundred volts, but there are other factors that tend to complicate the design and require higher voltages.

[0007] The first complication is the desire for an insulating top layer, which is often a requirement to ensure the long life of the touchscreen. If the touch surface is conductive, the air gap will tend to short out through the contact points, especially in the presence of water. In addition, if the system is required to be transparent, it is difficult to place the transparent conductor on the top surface without subjecting it to excessive wear and tear. For these reasons, electroadhesive systems typically coat the conductor with a durable insulating layer. However, this layer is in electrical series with the air gap. Thus, some of the applied voltage may drop across the insulating layer, thus reducing the available voltage to apply to the air gap.

[0008] Depending on the material properties, electric field strength, and thickness as well as frequency, the electrical impedance of the insulating layer may consist of a complex reactance, a resistance, or a combination of both. However, this complex impedance behavior can be represented by a less complex linear capacitance model and a linear resistance model. For purposes of explanation, the insulating layer is described herein exclusively as a series linear capacitance, but the invention is not limited to that case. If C_i is the lumped capacitance of the insulating layer and C_gap is the lumped capacitance of the air gap, the applied voltage that may be required to create a 100V voltage drop across the air gap is: V_applied = [(C_i + C_gap) / C_i] * 100 volts

[0009] For example, if C_i=C_gap, then V_applied is 200V. In general, the larger the value of C_i, the lower the operating voltage. This is consistent with thinner insulators having higher dielectric constants. For example, if an insulating layer is 6 microns thick and has a dielectric constant of 3, it has the same capacitance as a 2 micron air gap (assuming it has a dielectric constant of 1).

[0010] From the above, it is clear that the insulating layer may be very thin in practical designs (but may be thicker if the layer has a sufficiently low resistance or high dielectric constant). If the insulating layer is thin, a second practical problem is that scratches may occur, such as due to grains of sand being dragged across the surface that may damage the underlying electrodes. A partial solution to this problem is to ensure that the insulating layer is extremely scratch resistant. However, this solution may not be relied upon alone. Another solution (described in previous inventions (U.S. Pat. No. 10,120,447 and U.S. Patent Application Nos. 15 / 178,283 and 15 / 606,440, which are incorporated herein by reference in their entireties)) is to activate the conductive layer (which may be patterned into a set of electrodes) via capacitive coupling to another set of electrodes located in a deeper, more protected layer. In a typical embodiment, as shown in FIG. 6 of U.S. Pat. No. 10,210,447, both sets of electrodes are patterned on the same glass sheet. That is, the "haptic electrodes" are on the touch surface and are covered by the thin insulating layer mentioned above, and the "transmitting electrodes" are on the underside and are protected by the entire thickness of the glass sheet. Previously, this arrangement has been described as a "mirrored" arrangement of electrodes, since the shapes of the haptic electrodes and the transmitting electrodes can be nearly identical, and the electrodes can be nearly aligned to maximize capacitive coupling through the glass sheet. The advantage of this arrangement is that even if the haptic electrodes are damaged by a scratch, they can still be activated by coupling to the transmitting electrodes.

[0011] The capacitance from the transmit electrode to the haptic electrode is also in electrical series with the air gap capacitance, which causes an additional voltage drop. However, before estimating this voltage drop, one additional issue must be addressed: bipolar operation.

[0012] The '613 patent describes an architecture in which haptic electrodes are arranged in a pattern such that a finger placed on the touch surface covers two or more electrodes. If these electrodes are driven in opposite polarity with respect to the body ground, the voltage drop across the air gap is relatively independent of the strength of the coupling to the body ground. In other words, a well-grounded body and a poorly grounded body should feel the same intensity of haptics. This was a major advance over the prior art, which required the body to be well-grounded to deliver full intensity haptics.

[0013] The ideas presented above are available in the prior art and can be used to create practical electroadhesive devices. However, what is needed is a way to combine this with multi-touch sensing, the ability to measure and track the positions of multiple fingertips interacting with a touch surface. A practical multi-touch sensor should be able to distinguish between non-fingertips, such as water droplets or palms. The prior art has proposed various approaches, but none of them have proven to be as robust as state-of-the-art touch sensors, most of which are based on mutual capacitance measurements. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] U.S. Patent No. 9,733,746 Summary of the Invention

[0015] The present invention is an integrated system that provides very robust multi-touch sensing and, at the same time, very robust electroadhesive-based haptics. Similar to mutual capacitance-based touch sensors, the present invention is based on a set of transmitting electrodes (Tx), a set of receiving electrodes (Rx), and measurements corresponding to each Tx-Rx intersection, resulting in a two-dimensional image from which touch location can be extracted. However, the details are very different depending on the needs of integrating this sensor system with electroadhesive-based haptics.

[0016] In an exemplary embodiment of the present invention, an indirect haptic device is provided that includes a substrate having a touch surface including an upper surface and a lower surface, a first set of electrodes disposed on the upper surface of the substrate, and a second set of electrodes disposed on the lower surface of the substrate. The device further includes a position sensor configured to detect one or more touch locations of a user's extremity on the touch surface, and a friction modulator associated with the substrate and configured to modulate friction between the user's extremity and the touch surface. In addition, a control device is connected to the position sensor and the friction modulator, and the control device is configured to apply a bipolar electrical signal to the second set of electrodes to both detect one or more touch locations of the user's extremity on the touch surface and modulate friction between the user's extremity and the touch surface.

[0017] In an exemplary embodiment of the invention, a method is provided that includes providing a substrate having a touch surface including an upper surface and a lower surface, where a first set of electrodes is disposed on the upper surface of the substrate and a second set of electrodes is disposed on the lower surface of the substrate, the method further includes detecting one or more touch locations of a user's extremity on the touch surface via application of a bipolar electrical signal to the second set of electrodes, and modulating friction between the user's extremity and the touch surface via application of the bipolar electrical signal to the second set of electrodes.

[0018] The above features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the following drawings. [Brief description of the drawings]

[0019] [Figure 1A] FIG. 2 is a top view of a touch panel having haptic electrodes and sensing electrodes. [Figure 1B] FIG. 2 is a bottom view of a touch panel having haptic electrodes and sensing electrodes. [Figure 1C] FIG. 2 is a side view of a touch panel having haptic electrodes and sensing electrodes. [Diagram 2] FIG. 2 is a detailed view of a touch panel electrode. [Diagram 3] FIG. 1 is a partial view of the potential and capacitance in a region close to the finger position. [Figure 4] FIG. 13 illustrates another exemplary arrangement of a touch panel in which the Hx electrode pairs are stacked deeper on one another. [Diagram 5] FIG. 13 illustrates yet another exemplary approach to stacking of Hx and Tx electrodes with thinner electrodes. [Figure 6] 13A-13C are diagrams illustrating the effect of finger placement at various points above and near the electrodes on a touch panel. [Figure 7] 4 is another example layout of a touch panel according to the present disclosure. [Figure 8] 13 is yet another example layout of a touch panel according to the present disclosure. [Figure 9A] FIG. 2 is a diagram of a touch panel having guard electrodes according to one embodiment of the present disclosure. [Figure 9B] FIG. 2 is a diagram of a touch panel having guard electrodes, also according to one embodiment of the present disclosure. [Figure 10] 1A and 1B are diagrams of example configurations of a touch panel layer. [Figure 11] FIG. 1 is a diagram of one example configuration of a touch panel. [Figure 12] FIG. 2 is a diagram of another exemplary configuration of a touch panel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1A, 1B and 1C show the configuration of a first embodiment. In this embodiment, four types of electrodes are provided for and disposed on a sheet of glass 10. Transmit (Tx) electrodes 12 and receive (Rx) electrodes 14 are disposed on the bottom side 16 of the glass 10, away from the touch surface 18. Haptic (Hx) electrodes 20 and island (Is) electrodes 22 are disposed on the top side (touch side) 18 of the glass 10. It is noted that other configurations are possible. For example, each of the types of electrodes may be disposed on a different layer, and the layers may be disposed on different substrates, which may be assembled (e.g., laminated) in further processing steps. The substrate need not be glass, but may be other insulating or semiconducting materials, such as plastic, ceramic, or natural materials. Alternative configurations are described later in this document.

[0021] In this embodiment, the Tx lines 12 and Hx lines 14 may extend laterally across one dimension of the glass substrate, are aligned, and have substantially similar shapes. The electrodes need not extend laterally across the substrate, but may take different forms, such as localized patches or zigzags. In this embodiment, to maximize the capacitive coupling of the Tx lines 12 and Hx lines 14, the Tx lines 12 occupy a majority of the area of ​​the bottom side 16, while the Hx lines 14 occupy a majority of the area of ​​the top side 18. In a preferred embodiment, the glass substrate 10 may be 0.7 mm or less thick, preferably 0.4 mm or less thick, and the dielectric constant of the glass substrate 10 is at least 3, although a higher dielectric constant, e.g., 6 or greater, is preferred.

[0022] In this embodiment, the Rx lines 14 may run perpendicular to the Tx lines 12 and may be formed from substantially the same conductive layer, which may be indium tin oxide (ITO) with a resistivity of 45 ohms per square. Other conductors and other resistivities may be used. Where the Tx and Rx lines 12 and 14 cross, a conductive bridge 24 may be formed to ensure connectivity. The bridge 24 may be formed using techniques known in the art, such as placing a patch of polymer on a continuous electrode and then a strip of metal on the polymer, or connecting both sides of a discontinuous electrode. In a preferred embodiment, the Rx electrodes 14 are continuous, and two bridges 24 (as shown in FIG. 2) are formed for every Tx-Rx intersection 26. The use of more than one bridge reduces resistance and increases reliability. In addition, at each Tx-Rx intersection 26, both the Tx line 12 and the Rx line 14 should have sufficient area to provide significant capacitive coupling to an island (Is electrode) 22 aligned with the intersection 26 and disposed on the opposite side of the glass 10. In a preferred embodiment, the Is electrode 22 has an "asterisk" shape consisting of eight spokes extending from a central hub, although a variety of other shapes may be used. The underlying Rx electrode 14 may be aligned with four of the spokes, while the underlying Tx electrode 12 overlaps the remaining four spokes. This arrangement ensures capacitive coupling from both the Tx line 12 and the Rx line 14 to the corresponding Is electrode 22, the advantages of which are discussed below.

[0023] In a preferred embodiment, the Is electrodes 22 are disposed within the area of ​​each of the Hx electrodes 20. No bridges are required on the top side 18 in this embodiment because all the Hx electrodes 20 and Is electrodes 22 are formed from the same conductive sheet, which may be ITO with a resistivity of 150 ops, although lower or higher values ​​may also be used. Patterning of the electrodes may be achieved by techniques known in the art, such as photolithography, screen printing, or laser ablation.

[0024] In a preferred embodiment, the distance between adjacent Hx electrodes 20 (also known in the art as the erase line width) is greater than the distance between adjacent Tx electrodes 12. For example, the distance between adjacent Hx electrodes 20 may be 200 microns, while the distance between adjacent Tx electrodes 12 may be 60 microns. Other distances may be used as well, including embodiments in which the distance between adjacent Hx electrodes 20 is equal to or less than the distance between adjacent Tx electrodes 12. Also, rather than eliminating all ITO between adjacent electrodes, some amount of ITO, typically in the form of a small patch, may be maintained to minimize visibility of the erase line.

[0025] FIG. 3 is a partial view of the potential and capacitance in the area of ​​the preferred embodiment near the location of the finger 28. It is important to note that FIG. 3 is merely illustrative, is not to scale, and does not show all of the capacitive coupling that would appear in an actual system. Since the key concepts of this disclosure relate to haptics and sensing, FIG. 3 is used here to clarify them. FIG. 3 shows two Tx electrodes 12 (numbered n and n+1), both of which extend into the plane of the paper. Also shown is a single Rx electrode 14 (numbered m), which extends from left to right on the plane of the paper. In practice, the Tx electrode 12 and the Rx electrode 14 may be on the same plane or on different planes (e.g., the Rx electrode 14 is on a plane below or above the Tx electrode 12). Similarly, two Hx electrodes 20 (numbered n and n+1) are shown that are aligned with the Tx electrode 12 and are substantially the same shape as the Tx electrode 12. However, within each Hx electrode 20 are located multiple island (Is) electrodes 22, two of which are shown (numbered n×m and n+1×m). It should be noted that both the Hx and Is electrodes 20 and 22 are electrically and conductively insulated or isolated from the other Hx and Is electrodes 20 and 22, the body, and the rest of the electrical subsystem, as well as from the Tx and Rx electrodes 12 and 14. This means that the Hx and Is electrodes 20 and 22 do not make ohmic or direct connections to other conductive elements, but instead remain electrically floating. Thus, to assume any given electrical potential, the Hx and Is electrodes 20 and 22 can only interact with nearby elements (Tx and Rx electrodes 12 and 14, other Hx and Is electrodes 20 and 22, fingers 28, etc.) via local capacitive coupling. Figure 3 also shows finger 28 in a position where it interacts with both Hx electrodes 20, but much more strongly with one Is electrode 22 than the other. Also shown in Figure 3 are two high voltage rails and a switch connecting one Tx electrode 12 to a positive voltage and the other Tx electrode 14 to a negative voltage. A number of associated capacitances are shown and will be referenced in the discussion of haptics and sensing.

[0026] Note that in this illustrated preferred embodiment, both the body potentials and the device potentials (including the potentials of the various Tx, Rx, Hx, and Is electrodes) are referenced to the same local earth ground. However, this configuration is for illustrative purposes only and is not a requirement of the invention. In other embodiments, the device may be galvanically isolated from the local earth ground, for example by using known techniques such as an isolation transformer or a local battery power source, and therefore all device potentials may be referenced to the potential of the body, or some other point. In addition, the body potentials may or may not be held to local ground potential via an additional galvanic (direct) connection or a strong capacitively coupled connection. Indeed, one advantage to the sensing and electroadhesive actuation technique disclosed herein is that it is robust to a variety of grounding conditions, both body and device.

[0027] To achieve a strong electroadhesion effect, the difference between the Hx electrode 20 potential and the body potential is preferably as large as possible to create the maximum possible electric field across the air gap. In this exemplary case, the body potential is assumed to be close to the local earth ground, meaning that C_body is in a discharged state, while each Hx electrode 20 is as close as possible to the potential of its associated Tx electrode 12. In the illustrated configuration, Tx_n is set to +Vo volts relative to the local earth ground, while Tx_n+1 is set to -Vo volts. It can be shown that in the absence of fingers 28, the haptic electrodes achieve the following potentials: Hx_n=[C_z / (C_z+2*C_HH)]*Vo Hx_n+1=-Hx_n

[0028] To maximize the haptic electrode potential, it may be desirable to maximize C_z, the capacitance between each Hx electrode 20 and its mirror-image Tx electrode 12, and minimize C_HH, the mutual capacitance between neighboring Hx electrodes 20. The former suggests using wider and longer Hx (and Tx) electrodes and using thinner glass substrates with larger dielectric constants. The latter suggests wider erase lines between neighboring Hx electrodes 20. In addition, if the erase line width between neighboring Tx electrodes 12 is narrower (i.e., the Tx electrodes 12 are wider than the Hx electrodes 20), the Tx electrodes 12 will have a shielding effect, further reducing C_HH. This is a simplified analysis, and there are other factors that may be involved. For example, other voltages may be applied to other Tx electrodes 12, which in turn may affect the voltage of the Hx electrodes 20.

[0029] If a finger 28 is positioned above both Hx electrodes 20, the finger 28 can act as an additional mutual capacitance (i.e., additional C_HH) and can further reduce the Hx voltage. If half of a finger covers each polarity of the Hx electrodes 20, it can be shown that the haptic electrodes achieve the following potentials: Hx_n=[C_z / (C_z+2*C_HH+0.5*C_HF)]*Vo Hx_n+1=-Hx_n

[0030] To maximize the haptic electrode potential, it may be desirable to minimize C_HF, which is the capacitance between the entire set of Hx electrodes 20 and the finger. However, it should be understood that the electroadhesion effect also depends on the magnitude of C_HF. Thus, there may be an optimal value of C_HF for a given touch panel design. C_HF can be adjusted by modifying the thickness, composition, or roughness of the insulating layer covering the Hx and Is electrodes. Alternatively, C_HF may be adjusted by modifying the Hx and Is electrodes 20 and 22 themselves. For example, instead of forming these electrodes from a continuous sheet of conductor, these electrodes may be formed from a grid of conductors or from a sheet with many small holes. The areal density of the conductors can also be adjusted according to position on the Hx or Is electrodes to ensure the most uniform electric field strength possible. As yet another alternative, the Hx and Is electrodes 20 and 22 may be subdivided such that different portions achieve different electric potentials. This can help achieve a uniform electroadhesion strength, for example, regardless of the position of the finger on the touch surface.

[0031] In a preferred embodiment, the Hx (and Tx) electrodes are 5mm wide and span the entire length of the touch surface, although electrodes as narrow as 0.1mm or as wide as 20mm may be used; the erase line width between the Hx electrodes 20 is 200 microns, but may be as narrow as 10 microns or as wide as 1mm; and the erase line width between the Tx electrodes 12 is 60 microns, but may be as narrow as 10 microns or as wide as 1mm. The glass thickness is preferably 0.4mm, although thicknesses from 0.025mm to 3mm may be used. Also, the glass dielectric constant is 6-7, although dielectric constants from 3 to 80 may be used. In fact, the substrate may not be glass at all, but another dielectric material such as plastic, sapphire, or ceramic.

[0032] Bipolar Haptics and Body Potential In general, the body potential may not be at the earth ground potential, which means that C_body is not discharged. External factors such as triboelectrification may affect the body potential, but for simplicity, these factors are ignored here. More importantly, the Hx electrodes 20 themselves may affect the body potential relative to the device ground. Since the insulation covering the Hx electrodes 20 is typically very thin, a finger (or other body part) 28 touching the surface may be strongly coupled to those electrodes. If the finger 28 is strongly coupled to only a single Hx electrode 20, the body potential will tend to follow the potential of the Hx electrode 20. In situations where the body potential is weakly coupled to the earth ground, and thus to the device ground, this will result in a small potential difference between the body and the Hx electrodes 20, resulting in a weaker haptic effect. In conditions where the device ground is completely separated from the earth ground, this will leave no potential difference between the body and the Hx electrodes 20, resulting in virtually no haptic effect at all. For these reasons (and others including sensing), it is preferred that the Hx electrodes 20 operate in the bipolar manner described herein. Additionally, the Hx electrodes 20 may be configured such that the finger 28 touches more than one Hx electrode 20 at any one time. There are various electrode geometries that achieve this goal. FIG. 1A shows a preferred embodiment in which the Hx electrodes 20 are strips, but thin enough that the finger 28 will always touch more than one Hx electrode 20. FIG. 4 shows another exemplary arrangement in which the Hx electrode 20 pairs are stacked even further on top of each other to ensure that the finger covers a Hx electrode 20 pair of each polarity. Three rows of stacked bipolar electrodes are shown. The white "plus" are island electrodes 22, and the Hx (and Tx, not shown, which are "mirrored") electrodes 20 are arranged in pairs. In this image, the Tx electrodes 12 under the light grey electrodes (not shown) are activated with one polarity and the Tx electrodes 12 under the dark grey electrodes (not shown) are activated with the opposite polarity. The Tx electrodes 12 under the other Hx electrodes 20 are held at device ground potential.The electrode stacking is intended to ensure that a finger 28 placed anywhere on the Hx pair 20 is likely to cover roughly the same area of ​​each polarity, and therefore the body potential is maintained near the average of the two polarities. This is indicated by the circle 30 in the image, which represents a fingertip contact having an 8 mm diameter (the Is electrodes 22 are spread out on a 5 mm grid in this embodiment). As can be seen, the amount of each polarity (light and dark grey) under the finger 28 is roughly equal, and this is true for most finger positions.

[0033] FIG. 5 shows a different exemplary approach to stacking the Hx 20 and Tx 12 electrodes, which involves thinner electrodes. In this embodiment, the island electrodes 22 have the same 5 mm pitch shown in FIG. 1 and FIG. 4, but the Hx 20 and Tx 12 electrodes have a 2.5 mm pitch. This requires twice as many Tx lines 12, but this design has another advantage in addition to ensuring that the finger 28 contacts approximately equal portions of both polarities. A second advantage is that each Rx (not shown, but running vertically in the drawing) electrode 14 responds to only one polarity. Therefore, rather than resulting in a differential signal (as discussed below), this approach results in a signal that each varies in a single direction relative to ground. Alternatively, two nearby Rx lines 14 can be connected together and the balanced sensing method discussed in this disclosure can be applied.

[0034] With stacked geometries such as these (and many variations that should be apparent to one of ordinary skill in the art) and bipolar operation, the body potential is guaranteed to be halfway between the potentials of the two Hx electrodes 20, close to the device ground. In essence, the body is actively held close to a virtual device ground by the two opposite polarity Hx electrodes 20. The term virtual ground is used here not to indicate that the body is used as a low impedance sink or source, but rather that it is simply unaffected on average by the two Hx electrodes 20. In other words, operating the Hx electrodes 20 as a bipolar pair serves the function of canceling or balancing the overall effect on the body potential relative to the device and device ground.

[0035] Bipolar Detection The sensing is performed by measuring the signal transmitted from the Tx line 12 to the Rx line 14. For illustrative purposes, consider the case where a voltage is applied to a single Tx line 12 and measurements are made at a single Rx line 14. In a preferred embodiment, the same voltage rail used for the haptics is used for this purpose, but other voltages may also be used. The measurement is due in part to the mutual capacitance C_TR between the Tx electrode 12 and the Rx electrode 14, but in the present invention, C_TR is not affected by the presence of a finger. Thus, the present invention is not based on known techniques of mutual capacitance. Instead, the present invention can function as follows: When a voltage is applied to the Tx line 12, this causes the potential of the mirrored Hx line 20 to vary as already discussed. The Is electrode 22 present in that Hx electrode 20 also achieves a potential close to that of the Hx electrode 20 by coupling with both the Hx electrode 20 and the underlying Tx electrode 12. Each Is electrode 22 also affects the potential of the underlying Rx 14 electrode due to the capacitive coupling C_RI. When a finger is placed partially or fully on a given Is electrode 22 (e.g., Is_n×m), the potential of the Is electrode 22 is affected, which in turn affects the measurements related to Tx_n, Rx_m. In other words, the effect of the finger on the Is electrode 22 creates a signal.

[0036] In the present invention, the signaling on the panel can be controlled by pulsing the Tx electrodes 12 in a bipolar manner. This means that in each measurement, there are one or more Tx electrodes 12 pulsing in the positive direction and an equal number of Tx electrodes 12 pulsing simultaneously in the negative direction. In a preferred embodiment, the positive and negative Tx electrodes 12 are adjacent (if Tx_n is positive going, Tx_n-1 is negative going), and the sense pulse cycles through the Tx electrodes 12 in sequence, with a measurement made on the Rx line 14 for each pulse.

[0037] The effect of a bipolar pulse on a measurement depends on the layout of the touch panel. For example, consider the panel design shown in FIG. 1. Due to the bipolarity of the signal, the contributions from Is_n×m and Is_n+1×m are cancelled or balanced. When there is no fingertip touching the panel, the capacitance load is balanced and little or no signal is measured on either Rx line 14. When a fingertip touches the panel, the Is electrode 22 under the fingertip is loaded more heavily and the load unbalance results in a signal on the Rx line 14 under the touched Is electrode 22.

[0038] Consider a fingertip centered over island electrode 22 Is_n×m and the sensed signal consists of a positive pulse on Tx_n 12 and a negative pulse on Tx_n-1 12. Due to the very thin insulating layer, the finger has a strong capacitive coupling to the Is_n×m electrode 22, substantially affecting its potential. As discussed above, bipolar actuation keeps the finger close to the device ground, and therefore the finger tends to pull the Is electrode 22 towards the virtual device ground. In this case, since Is_n×m overlays the positively pulsed Tx_n electrode 12, the load becomes unbalanced towards the negatively pulsed Tx_n-1 12 and the Rx_m electrode 14 receives a negative signal. In the next period in the sequence, Tx_n 12 is the negatively pulsed electrode and the Rx_m electrode 14 receives a positive signal due to the load unbalancing.

[0039] Now, if we consider a fingertip that equally loads two adjacent Is electrodes 22 (Is_n-1×m and Is_n×m), the expected output signal on Rx_m 14 will be different: in this case, the Rx_m electrode 14 will receive a zero signal when the Tx_n-1 and Tx_n pair 12 are activated, but will receive a signal when the Tx_n-2 and Tx_n-1 pair 12 are activated, and similarly when the Tx_n and Tx_n+1 pair 12 are activated.

[0040] A fingertip that is intermediate between the two above mentioned cases will exhibit a combination of these two signal types and its position can be inferred through interpolation between the two loading conditions.

[0041] FIG. 6 shows an example of how the resulting signal can change when a fingertip 28 slides from one Is electrode 22 to another Is electrode 22 along the direction of the Rx electrodes 14. In this figure, an array of four electrodes is shown, Is_n-1×m to Is_n+2×m 22. Centered beneath each pair of electrodes is an arrow 32 that represents the expected signal measured on Rx_m 14, assuming that the Tx electrode (not shown) above and to the left of each pair of electrodes is pulsed negatively and the Tx electrode (not shown) above and to the right of each pair is pulsed positively. In the first example shown in FIG. 6 (referenced by a circled "A"), the finger 28 (shown as a rounded rectangle) is centered above electrode Is_n×m 22 and is heavily loading that electrode. If Is_n-1xm 22 is pulsed negatively and Is_nxm 22 is pulsed positively, the resulting Rx_m 14 signal is a strong negative signal. If in the next step Is_nxm 22 is pulsed negatively and Is_n+1xm 22 is pulsed positively, the resulting Rx_m 14 signal is a strong positive signal. If in the next step Is_n+1xm 22 is pulsed negatively and Is_n+2xm 22 is pulsed positively, the resulting Rx_m 14 signal remains at zero. These signals are indicated in the figure by downward (negative) and upward (positive) arrows.

[0042] The second through fourth examples shown in FIG. 6 (referenced by the circled "A", "B", and "C") roughly show how the signal results given different fingertip positions. In this illustration, it can be clearly seen that the choice of which electrodes are driven negatively and which electrodes are driven positively has a substantial effect on the signal. Thus, it is possible to choose different bipolar arrangements to get more information about the fingertip or other body part (e.g., palm) touching the panel without departing from the spirit of the invention, which is to use bipolar pulses for sensing, as well as haptics. For example, in some situations it may be desirable to space the positive and negative facing electrodes by one electrode, rather than adjacent to each other. This may enhance the signal in certain situations. It should be understood that alternative choices for the signaling sequence are also part of the invention.

[0043] Alternative Panel Layouts As mentioned above, the effect of bipolar pulse driving depends on the layout of the panel. Instead of the layout of FIG. 1, an alternative layout shown in FIG. 7 may be used. The key difference is that in FIG. 1, all Tx 12 were coupled to all Rx 14, while in FIG. 7, every other Tx 12 is coupled to every other Rx 14. Thus, if a pair of bipolar pulses is delivered to two adjacent Tx lines 12 (e.g., the two lower shaded lines), the positive going pulse will couple primarily to half of the Rx lines 14, while the negative going pulse will couple primarily to the other half of the Rx lines 14. Note that here the island electrodes 22 are diamond shaped rather than a square grid, but other arrangements may be used. To maintain the same or similar center-to-center distance between the island electrodes 22 as seen in FIG. 1, the pitch of both the Tx electrodes 12 and the Rx electrodes 14 may be reduced to around one square root of two. Thus, this panel may have approximately 41% more Tx electrodes 12, Rx electrodes 14, and Hx electrodes 20. However, it will be apparent to one skilled in the art that this is merely one example layout and that many other panel layouts are possible within the spirit of the present invention. As one further example, it is possible to use an arrangement of Tx electrodes 12 such as that shown in FIG. 1B, but with twice as many Rx electrodes 14. Each Rx electrode 14 may be configured to couple to every other Tx electrode 12. In this way, each Rx electrode 14 couples to only a single polarity, rather than both polarities.

[0044] Instead of making an independent measurement for each Rx line 14, it is also possible to make a differential measurement. For example, instead of making separate measurements for Rx_i and Rx_i+2, it is possible to measure Rx_i+2-Rx_i. This has two advantages: it reduces the number of channels that need to be read and it eliminates common mode noise.

[0045] Although the layout of FIG. 7 maintained a “mirror” relationship between the Tx electrodes 12 and the Hx electrodes 20, this is not necessary. For example, as shown in FIG. 8, each Hx electrode 20 can actually span two Tx electrodes 12. With this panel design, sensing can function much the same as sensing in FIG. 6. That is, a bipolar pulse is applied to two nearby Tx electrodes 12 that share a common Hx electrode 20. While the Hx electrode 20 is maintained at approximately ground potential, the island electrode 22 still floats in the direction of the underlying Tx electrode 12 due to capacitive coupling C_TI. In particular, the finger 28 placed over the island 22 will pull the island 22 back toward ground, since the finger 28 is strongly coupled to the ground potential Hx electrode 20. As an alternative, the Is electrode 22 can be removed entirely and replaced with an opening in the Hx electrode 20 (which may be, for example, a circular hole, an asterisk shape, or a slit) (not shown). In this design, some of the field lines that originate at the Tx electrodes 12 are projected above the touch surface before coupling back to the Rx electrodes 14. A finger placed over the aperture acts to deflect those field lines, producing a measurable change in the signal received at the Rx electrodes 14. Four Tx electrodes 12 are used to create the haptics, although other numbers of Tx electrodes 12 may be used. The two Tx electrodes 12 under a given Hx 20 operate at the same polarity, while the two Tx electrodes 12 under a nearby Hx 14 operate at the opposite polarity.

[0046] Although the preferred embodiment involves the Tx electrodes 12 and Hx electrodes 14 being shaped as long strips running from one side of the touch panel 10 to the other, this need not be the case. The present invention can tolerate a variety of electrode shapes, so long as the electrodes can be operated in a bipolar fashion. For example, it may be desirable to use electrodes that are serpentine shaped, and that occupy dense areas of the panel rather than extending from one side to the other. This can be useful, for example, in localizing haptic areas.

[0047] Further advantages of bipolar sensing and actuation The use of bipolar sensing and haptic signaling also has a dramatic effect on the radiated emissions by the device to the outside world. This is highly desirable if this radiated emission can affect the fidelity or reliability of nearby circuits or wireless receivers. The electromagnetic emission capability of a given electrical conductor depends not only on the amount of current or voltage currently applied to it, but also on the length and geometry of the conductor. In the present invention, and in the preferred embodiment, nearby lines share nearly identical geometries and electrical transient responses. This is why bipolar signaling on the panel reduces radiated emissions. This is because the pairs of Tx lines 12 and Hx lines 14 are driven in opposite polarity and similar strengths, meaning that their emissions essentially balance each other. This is especially true in the far field, but the effect is still noticeable and influential near the panel and the electrodes themselves. To achieve this balancing, it is helpful to balance as many aspects of the positive and negative signals as possible. For example, the positive and negative power rails can be matched, the slew rates for switching signals on and off can be matched, and the total resistance and capacitance of each Tx line 12 can be matched to the total resistance and capacitance of every other Tx line 12, and similarly, the total resistance and capacitance of each Rx line 14 can be matched to the total resistance and capacitance of every other Rx line 14.

[0048] Another advantage of bipolar signaling is the added safety it provides to the user with respect to unintentional touch currents, also called device leakage currents. This current is defined as the unintentional current that flows between the device and the user under normal tactile contact with the device and returns to earth ground. International safety standards specify waveform limits (both amplitude and frequency) for this touch current in various types of products, such as medical devices, consumer devices, etc., and by adhering to these standards, the majority of products on the market are deemed safe for use. Bipolar sensing and haptic signaling reduces unintentional electroadhesion touch currents to very low levels. This is again due to the balanced nature of the signal and the fact that the device tends to leave the body potential near the virtual device ground. This means that there is no current path for the touch current to return through the body to the local earth ground. Essentially, this means that any positive current applied to the body by the device is simultaneously balanced by a corresponding negative current also applied by the device at the point of contact. This limits the overall amplitude of the current traveling through the body and the possible current paths the current can take.

[0049] Another advantage of bipolar actuation is that high voltage bipolar actuation signals can be arranged so that they can be completely cancelled by bipolar sense signals. Just as bipolar actuation signals can be geometrically configured to balance the effect they have on the body, so that the body can be held at virtual ground, they can also be geometrically configured to balance their effect on the Tx and Rx electrodes 12 and 14 in the sense circuit of the present invention. In this way, the higher voltage haptic actuation circuit will not have interaction with the lower voltage sense circuit. The actuation circuit leaves the sense circuit unaffected. This may allow fewer high voltage circuits to be used for actuation while at the same time using more low voltage circuits for sensing. This may result in reduced cost, complexity, and power consumption, among other advantages. In this embodiment, the Rx electrodes 14 can be configured similarly to those in FIG. 1B, while the backside Hx electrodes 20 can replace the Tx electrodes 12. 1A in the same manner as the original Tx electrodes 12. In that case, additional low voltage Tx electrodes 12 may be placed directly between the back Hx electrodes 20, and the sense node and Is electrode may be relocated to the new intersection 26 of the Tx 12 and Rx 14 between the Hx electrodes 20.

[0050] Self-Capacitance Sensing The techniques described above for controlling both electroadhesive haptics and sensing the state of individual Tx-Rx nodes 26 may be combined with self-capacitance sensing. Typically, self-capacitance is used as a means of measuring the state of individual electrodes (e.g., Tx electrodes 12) rather than electrode nodes 26. In a typical embodiment, a voltage is applied to the electrode while the current is measured and integrated and the associated charge is estimated. The capacitance is estimated as the ratio of the charge to the applied voltage, and the capacitance will depend on the presence of a nearby conductive object, such as a human finger. Although self-capacitance is known to be problematic for multi-touch sensing, it is a fast and efficient way to gather some information about the state of the touch. Self-capacitance is also very useful for clarifying objects such as a human body, which is large and well coupled from the object to earth ground, and a water droplet, which is small and poorly coupled. Often, self-capacitance is used in conjunction with mutual capacitance measurements.

[0051] In the present invention, bipolar self-capacitance measurements can supplement or even replace the bipolar measurements described above. The signaling is similar to that described, but the measurements are made on the integral of the current on the Tx electrodes 12, rather than the signal received on the Rx electrodes 14. The same set of electrodes can be used for both self-capacitance and mutual capacitance measurements, or alternatively, different electrodes can be used for each function. For example, self-capacitance and mutual capacitance electrodes can be alternated. Instead of measuring the integral of the current on the Tx electrodes 12, the self-capacitance can be estimated by summing the signal across all the Rx electrodes 14 when a signal is transmitted to a particular Tx electrode 12.

[0052] Guard Electrode In a preferred embodiment, an electrical signal is introduced to the underside 16 of the substrate 10 while simultaneously capacitively coupling the electrodes (Hx 20, Is 22) on the topside. Typically, the electrical signal is introduced via a flex cable, although other types of connectors may be used. Conductive traces may be used to distribute the underside signal from the point where the flex cable attaches to the Tx and Rx electrodes 12 and 14. These traces are themselves a source of radiated emissions. To limit emissions, a guard electrode 38 (shown in FIGS. 9A and 9B) may be placed around the periphery of the topside, which may be capacitively coupled to a ground electrode on the underside 16. The ground electrode 38 may be large, taking up most of the periphery of the underside 16 except for the area occupied by the conductive traces.

[0053] A further advantage of the top guard electrode 38 is that it maintains the same overall optical stack-up as found elsewhere on the panel. In other words, with the exception of the erase lines that define the Hx and Is electrodes 20 and 22, the top conductive layer 18 is uniform.

[0054] Panel Configuration There are many possible ways to manufacture a haptic touch panel with the electrode arrangement and insulating layers considered in the present invention. The present invention relies on four main components: a patterned conductive layer 1 for the Rx electrodes 14, a patterned conductive layer 2 for the Tx electrodes 12, a patterned conductive layer 3 for the Hx electrodes 20 and Is electrodes 22, and a protective dielectric covering the Hx electrodes 20 and Is electrodes 22. These layers can be on one or more substrates, along with other layers such as index matching layers, buffer layers, anti-reflective layers, oleophobic layers, etc., depending on the application and customer demand as shown in FIG. 10. Note that FIG. 10 does not include all possible configurations. For example, one possible configuration includes a top layer that is oleophilic rather than oleophobic. An oleophobic coating can limit the migration of body oils to the touch surface, while an oleophilic coating can facilitate the migration of these oils and even the spreading of the oils across the surface.

[0055] In a preferred embodiment, the substrate 10 is glass and is etched on the top (touch) surface. The use of an etched or textured substrate can result in increased haptic strength while keeping the applied voltage, contact area, and thickness of the dielectric layer the same. As an alternative to using a textured substrate, a texture can be applied on the substrate. For example, nanoparticles can be added to the insulating layer above the Hx and Is electrodes 20 and 22, or the insulating layer itself can be precisely textured, for example using plasma etching. A further advantage of a textured touch surface is that it can ensure haptic uniformity over all environmental conditions, including high and low temperatures and high and low humidity.

[0056] As mentioned above, FIG. 10 does not cover all possible configurations and ways to construct the device. For example, rigid or flexible plastic or any other type of substrate, whether transparent, translucent, or opaque, can be used in place of or in combination with either glass or film substrates. Anti-spalling, which is important for head impact in automotive applications or safety concerns in other markets, can be achieved by optically bonding the device substrate or the device itself to the display or to a mounting surface. If the top (touch surface) is either a film (flexible) or rigid plastic substrate, automotive head impact specifications are easily achieved.

[0057] The preferred embodiment described here is referred to as OGS+ (One Glass Solution+) configuration and is shown in FIG. 11. However, the substrate 10 does not have to be glass, but can be any insulating or semiconductive material such as plastic, leather, wood, cloth, etc., with the haptic electrodes 20 on the touch surface and the Rx electrodes 14 and Tx electrodes 12 on the opposite surface. FIG. 11 shows just one possible OGS+ stackup (i.e., set of layers) on a glass substrate. A dielectric hard coating layer 40 is the top layer, followed by a patterned ITO layer 42 that includes the Hx electrodes 20 and the Is electrodes 22. The next layer is a glass layer 44, then a black border 46. A second patterned ITO layer 48 that includes the Tx electrodes 12 and the Rx electrodes 14 follows next. That layer is followed by a polymer insulating layer 50, jumpers and metal traces 52, then a passivation layer 54.

[0058] For applications requiring flexible devices, 3D or 2.5D shapes, or spalling resistance, the top side may be made of a film. The film may be PET, PEN, PC, COC, COP, PMMA, etc. and will have a conductive layer 42 and a dielectric hard coating 40 (FIG. 12). Again, other coatings such as anti-fingerprint and AR layers may be added. The bottom electrode may be placed on the glass or may be placed on the film 56 as well, resulting in a film-film configuration.

[0059] It is understood that the above configurations can be applied to other materials such as cloth, leather, thin glass (0.2 mm thick or less), etc. Also, the haptic film / Tanvas sensor can be used in insert molding manufacturing or other similar processes to produce devices with complex three-dimensional shapes.

[0060] While certain illustrative embodiments of the present invention have been described above, those skilled in the art will understand that changes and modifications can be made to those embodiments without departing from the spirit and scope of the invention, as set forth in the appended claims.

Claims

1. a substrate having a touch surface including a top surface and a bottom surface; a plurality of haptic electrodes and a plurality of island electrodes disposed on the top surface of the substrate; a plurality of transmitting electrodes and a plurality of receiving electrodes disposed on the lower surface of the substrate; a position sensor configured to detect one or more touch positions of a user's extremities on the touch surface; a friction modulator associated with the substrate and configured to modulate friction between the user's extremity and the touch surface; a control device connected to the position sensor and the friction modulator; Equipped with the control device is configured to apply bipolar electrical signals to the plurality of transmitting electrodes to both detect one or more touch locations of a user's extremities on the touch surface and to modulate friction between the user's extremities and the touch surface; each of the plurality of haptic electrodes is substantially aligned with and capacitively coupled to a corresponding two of the plurality of transmitting electrodes; the plurality of haptic electrodes extend laterally across the top surface of the substrate in a first direction, the plurality of transmitter electrodes extend laterally across the bottom surface of the substrate in the first direction, and the plurality of receiver electrodes extend laterally across the top surface of the substrate in a second direction that is substantially perpendicular to the first direction such that the plurality of transmitter electrodes and the plurality of receiver electrodes form a plurality of intersections; each of the plurality of island electrodes is aligned on the top surface with one of the plurality of intersections to form a capacitive coupling between the one of the plurality of intersections and the corresponding island electrode on the top surface; An indirect haptic device, wherein the user's electrical potential voltage affects an electrical potential voltage of at least one of the plurality of island electrodes when the user's extremity contacts the touch surface.

2. 2. The indirect haptic device of claim 1, wherein the plurality of transmitting electrodes includes a first pair of transmitting electrodes corresponding to and substantially aligned with a first haptic electrode of the plurality of haptic electrodes, and a second pair of transmitting electrodes corresponding to and substantially aligned with a second haptic electrode of the plurality of haptic electrodes, and the control device is configured to apply a positive voltage signal to the first pair of transmitting electrodes and a negative voltage signal to the second pair of transmitting electrodes to generate a haptic response.

3. 2. The indirect haptic device of claim 1, wherein the control device is configured to apply a positive voltage signal to a first transmitting electrode of the plurality of transmitting electrodes and a negative voltage signal to a second transmitting electrode of the plurality of transmitting electrodes, the first transmitting electrode and the second transmitting electrode being substantially aligned with a first haptic electrode, and a combined signal applied to the first haptic electrode by the positive voltage signal and the negative voltage signal being substantially close to a ground potential voltage to enable sensing.

4. The indirect haptic device of claim 1 , wherein the plurality of island electrodes do not have any ohmic or direct connections to other conductive elements of the indirect haptic device.

5. 2. The indirect haptic device of claim 1, wherein the plurality of haptic electrodes includes a first group having a positive polarity and a second group having a negative polarity, and when the user's extremity contacts the touch surface, the user's electrical potential voltage is affected by both the positive polarity of at least one of the haptic electrodes of the first group and the negative polarity of at least one of the haptic electrodes of the second group.

6. The indirect haptic device of claim 5, wherein the potential voltage of the haptic electrode affects the potential voltage of the user when the user's extremity contacts the touch surface, and the potential voltage of the user affects the potential voltage of each of the multiple island electrodes contacted by the user's extremity.

7. The indirect haptic device of claim 1 , wherein the plurality of haptic electrodes and the plurality of island electrodes do not have any ohmic or direct connections to other conductive elements of the indirect haptic device.

8. The indirect haptic device of claim 1 , wherein the plurality of haptic electrodes are arranged such that each of the plurality of haptic electrodes at least partially overlaps another of the plurality of haptic electrodes.

9. 2. The indirect haptic device of claim 1, wherein the control device is configured to apply a positive pulse to the transmitting electrodes of a first group and a negative pulse to the transmitting electrodes of a second group, the number of electrodes in the first group and the second group being the same.

10. The indirect haptic device of claim 1 , wherein one or both of the upper and lower surfaces of the substrate are etched.

11. The indirect haptic device of claim 1, wherein the bipolar electrical signal includes at least one positive signal and at least one negative signal, and the control device is further configured to balance the application of the amplitude of the at least one negative signal and the amplitude of the at least one positive signal such that the absolute amplitude of the signals applied by the control device is substantially near ground voltage.

12. providing a substrate having a touch surface including an upper surface and a lower surface, a plurality of haptic electrodes and a plurality of island electrodes disposed on the upper surface of the substrate, and a plurality of transmitting electrodes and a plurality of receiving electrodes disposed on the lower surface of the substrate; applying a bipolar electrical signal to the plurality of transmitter electrodes; detecting one or more touch locations on a user's extremity via the bipolar electrical signal; modulating friction between the user's extremities and the touch surface via application of a bipolar electrical signal to the plurality of transmitting electrodes; each of the plurality of haptic electrodes is substantially aligned with and capacitively coupled to a corresponding two of the plurality of transmitting electrodes; the plurality of haptic electrodes extend laterally across the top surface of the substrate in a first direction, the plurality of transmitter electrodes extend laterally across the bottom surface of the substrate in the first direction, and the plurality of receiver electrodes extend laterally across the top surface of the substrate in a second direction that is substantially perpendicular to the first direction such that the plurality of transmitter electrodes and the plurality of receiver electrodes form a plurality of intersections; each of the plurality of island electrodes is aligned on the top surface with one of the plurality of intersections to form a capacitive coupling between the one of the plurality of intersections and the corresponding island electrode on the top surface; The method of claim 1, wherein the user's electrical potential voltage affects the electrical potential voltage of at least one of the plurality of island electrodes when the user's extremity contacts the touch surface.

13. the plurality of haptic electrodes extend laterally across the top surface of the substrate in a first direction, and the plurality of transmit electrodes extend laterally across the bottom surface of the substrate in the first direction; the plurality of receive electrodes extend laterally across the top surface of the substrate in a second direction that is substantially perpendicular to the first direction such that the plurality of transmit electrodes and the plurality of receive electrodes form a plurality of intersections; 13. The method of claim 12, wherein each of the plurality of island electrodes is aligned on the top surface with one of the plurality of intersections to form a capacitive coupling between one of the plurality of intersections and the corresponding island electrode on the top surface.

14. 14. The method of claim 13, wherein the step of applying the bipolar electrical signal further comprises applying a positive pulse to a first group of the plurality of transmitter electrodes and a negative pulse to a second group of the plurality of transmitter electrodes, the number of electrodes in the first group and the second group being the same.

15. a substrate having a touch surface including a top surface and a bottom surface; a plurality of haptic electrodes and a plurality of island electrodes disposed on the top surface of the substrate, the plurality of haptic electrodes extending laterally across the top surface of the substrate in a first direction; a plurality of transmit electrodes and a plurality of receive electrodes disposed on the lower surface of the substrate, the plurality of transmit electrodes extending laterally across the lower surface of the substrate in the first direction; a position sensor configured to detect one or more touch positions of a user's extremities on the touch surface; a friction modulator associated with the substrate and configured to modulate friction between the user's extremity and the touch surface; a control device connected to the position sensor and the friction modulator; Equipped with the control device is configured to apply bipolar electrical signals to the plurality of transmitting electrodes to both detect one or more touch locations of a user's extremities on the touch surface and to modulate friction between the user's extremities and the touch surface; the plurality of haptic electrodes extend laterally across the top surface of the substrate in a first direction, the plurality of transmitter electrodes extend laterally across the bottom surface of the substrate in the first direction, and the plurality of receiver electrodes extend laterally across the top surface of the substrate in a second direction that is substantially perpendicular to the first direction such that the plurality of transmitter electrodes and the plurality of receiver electrodes form a plurality of intersections; each of the plurality of island electrodes is aligned on the top surface with one of the plurality of intersections to form a capacitive coupling between the one of the plurality of intersections and the corresponding island electrode on the top surface; An indirect haptic device, wherein the user's electrical potential voltage affects an electrical potential voltage of at least one of the plurality of island electrodes when the user's extremity contacts the touch surface.

16. the plurality of haptic electrodes extend laterally across the top surface of the substrate in a first direction, and the plurality of transmit electrodes extend laterally across the bottom surface of the substrate in the first direction; The indirect haptic device of claim 15 , wherein each of the plurality of haptic electrodes is substantially aligned with a corresponding one of the plurality of transmitting electrodes.

17. the plurality of transmitter electrodes extend laterally across the bottom surface of the substrate in a first direction, and the plurality of receiver electrodes extend laterally across the top surface of the substrate in a second direction that is substantially perpendicular to the first direction, such that the plurality of transmitter electrodes and the plurality of receiver electrodes form a plurality of intersections; The indirect haptic device of claim 15 , wherein the top surface of the substrate has a plurality of openings corresponding to each of the plurality of intersections.

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