WO2021163678A1 - Non-conductive capacitive sensing - Google Patents

Abstract

A sensor system is formed having a plurality of layers. A top layer is located adjacent to an intermediate layer. The intermediate layer is located adjacent to the sensor layer. In an embodiment, the intermediate layer is adapted to be compressible. In an embodiment, the top layer and the intermediate layer are adapted to be similar to skin in terms of texture and tactile feel. The sensor layer is adapted to determine touch events occurring through interaction with the top layer and intermediate layer.

Description

NON-CONDUCTIVE CAPACITIVE SENSING FIELD

[0001] The disclosed systems relate in general to the field of sensing, and in particular to sensing devices that are adapted to capacitively sense events through non- conductive surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS [0002] The foregoing and other objects, features, and advantages of the disclosure will be apparent from the following more particular description of embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the disclosed embodiments. [0003] FIG. 1 is a diagram of a layer arrangement having a top layer of polyurethane, an intermediate layer of silicone rubber and a bottom layer that forms a sensor layer.

[0004] FIG. 2 is a diagram of a layer arrangement having a top layer of polyurethane, an intermediate layer of agar and a bottom sensor layer.

[0005] FIG. 3 is a diagram showing touch events on an arrangement of conductors forming a sensor layer.

[0006] FIG. 4 is a diagram showing a touch event on an arrangement of conductors forming a sensor layer.

[0007] FIG. 5 is a diagram showing touch events touch on an arrangement of conductors forming a sensor layer.

[0008] FIG. 6 shows a sensor system implementing indium tin oxide (ITO) as a top layer, silicone rubber as an intermediate layer and a bottom sensor layer.

[0009] FIG. 7 shows a sensor system implementing conductive fabric as a top layer, silicone rubber as an intermediate layer and a bottom sensor layer.

[0010] FIG. 8 shows a sensor system with an arrangement of conductors for the sensor layer and an ITO layer as the top layer located on the sensor layer.

[0011] FIG. 9 shows a sensor system with an arrangement of conductors for the sensor layer and a conductive fabric layer as the top layer located on the sensor layer. [0012] FIG. 10 shows a sensor system with an arrangement of conductors for the sensor layer. [0013] FIG. 11 shows a sensor system implementing ITO as a top layer, agar as an intermediate layer and a sensor layer as a bottom layer.

[0014] FIG. 12 shows a sensor system implementing conductive fabric as a top layer, agar as an intermediate layer and a sensor layer as a bottom layer.

[0015] FIG. 13 shows a sensor system implementing ITO as a top layer, polyurethane as an intermediate layer and a bottom sensor layer.

[0016] FIG. 14 shows a sensor system implementing conductive fabric as a top layer, polyurethane as an intermediate layer and having a sensor layer as the bottom layer.

DETAILED DESCRIPTION

[0017] The present application contemplates a sensing device implementing fast multi-touch sensing (FMT) chips. FMT chips are suited for use with frequency orthogonal signaling techniques (see, e.g., U.S. Patent Nos. 9,019,224 and 9,529,476, and U.S. Patent No. 9,811 ,214, all of which are hereby incorporated herein by reference). The sensor configurations discussed herein may be used with other signal techniques including scanning or time division techniques, and/or code division techniques. The sensors described and illustrated herein are also suitable for use in connection with signal infusion (also referred to as signal injection) techniques and apparatuses.

[0018] The presently disclosed systems and methods involve principles related to and for designing, manufacturing and using capacitive based sensors, and particularly capacitive based sensors that employ a multiplexing scheme based on orthogonal signaling such as but not limited to frequency-division multiplexing (FDM), code-division multiplexing (CDM), or a hybrid modulation technique that combines both FDM and CDM methods. References to frequency herein could also refer to other orthogonal signal bases. As such, this application incorporates by reference Applicants’ prior U.S. Patent No. 9,019,224, entitled “Low-Latency Touch Sensitive Device” and U.S. Patent No. 9,158,411 entitled “Fast Multi-Touch Post Processing.” These applications contemplate FDM, CDM, or FDM/CDM hybrid touch sensors which may be used in connection with the presently disclosed sensors. In such sensors, interactions are sensed when a signal from a row conductor is coupled (increased) or decoupled (decreased) to a column conductor and the result received on that column conductor. By sequentially exciting the row conductors and measuring the coupling of the excitation signal at the column conductors, a heatmap reflecting capacitance changes, and thus proximity, can be created.

[0019] This application also employs principles used in fast multi-touch sensors and other interfaces disclosed in the following: U.S. Patent Nos. 9,933,880; 9,019,224; 9,811 ,214; 9,804,721 ; 9,710,113; and 9,158,411. Familiarity with the disclosure, concepts and nomenclature within these patents is presumed. The entire disclosures of those patents and the applications incorporated therein by reference are incorporated herein by reference. This application also employs principles used in fast multi-touch sensors and other interfaces disclosed in the following: U.S. Patent Applications 15/162,240; 15/690,234; 15/195,675; 15/200,642; 15/821 ,677; 15/904,953; 15/905,465; 15/943,221 ; 62/540,458, 62/575,005, 62/621 ,117, 62/619,656 and PCT publication PCT/US2017/050547, familiarity with the disclosures, concepts and nomenclature therein is presumed. The entire disclosure of those applications and the applications incorporated therein by reference are incorporated herein by reference.

[0020] As used herein, and especially within the claims, ordinal terms such as first and second are not intended, in and of themselves, to imply sequence, time or uniqueness, but rather, are used to distinguish one claimed construct from another. In some uses where the context dictates, these terms may imply that the first and second are unique. For example, where an event occurs at a first time, and another event occurs at a second time, there is no intended implication that the first time occurs before the second time, after the second time or simultaneously with the second time. Flowever, where the further limitation that the second time is after the first time is presented in the claim, the context would require reading the first time and the second time to be unique times. Similarly, where the context so dictates or permits, ordinal terms are intended to be broadly construed so that the two identified claim constructs can be of the same characteristic or of different characteristics. Thus, for example, a first and a second frequency, absent further limitation, could be the same frequency, e.g., the first frequency being 10 Mhz and the second frequency being 10 Mhz; or could be different frequencies, e.g., the first frequency being 10 Mhz and the second frequency being 11 Mhz. Context may dictate otherwise, for example, where a first and a second frequency are further limited to being frequency orthogonal to each other, in which case, they could not be the same frequency. [0021] Throughout this disclosure, the terms “touch”, “touches”, “touch event”, “contact”, “contacts”, “hover”, or “hovers” or other descriptors may be used to describe events or periods of time in which a user’s finger, an object, or a body part is detected by a sensor. In some sensors, detections occur only when the user is in physical contact with a sensor, or a device in which it is embodied. In some embodiments, and as generally denoted by the word “contact”, these detections occur as a result of physical contact with a sensor, or a device in which it is embodied. In other embodiments, and as sometimes generally referred to by the term “hover”, the sensor may be tuned to allow for the detection of “touches” that are hovering at a distance above the touch surface or otherwise separated from the sensor device and causes a recognizable change, despite the fact that the conductive or capacitive object, e.g., a finger, is not in actual physical contact with the surface. Therefore, the use of language within this description that implies reliance upon sensed physical contact should not be taken to mean that the techniques described apply only to those embodiments; indeed, nearly all, if not all, of what is described herein would apply equally to “contact” and “hover”, each of which is a “touch” or “touch event”. Generally, as used herein, the word “hover” refers to non-contact touch events or touch, and as used herein the term “hover” is one type of “touch” in the sense that “touch” is intended herein. Thus, as used herein, the phrase “touch event” and the word “touch” when used as a noun include a near touch and a near touch event, or any other gesture that can be identified using a sensor. “Pressure” refers to the force per unit area exerted by a user contact (e.g., presses by their fingers or hand) against the surface of an object. The amount of “pressure” is similarly a measure of “contact”, i.e. , “touch”. “Touch” refers to the states of “hover”, “contact”, “pressure”, or “grip”, whereas a lack of “touch” is generally identified by signals being below a threshold for accurate measurement by the sensor. In accordance with an embodiment, touch events may be detected, processed, and supplied to downstream computational processes with very low latency, e.g., on the order of ten milliseconds or less, or on the order of less than one millisecond.

[0022] Certain principles of a fast multi-touch (FMT) sensor have been disclosed in the patent applications discussed above. Orthogonal signals are transmitted into a plurality of transmitting conductors (or antennas) and the information received by receivers attached to a plurality of receiving conductors (or antennas), the signal is then analyzed by a signal processor to identify touch events. The transmitting conductors and receiving conductors may be organized in a variety of configurations, including, e.g., a matrix where the crossing points form nodes, and interactions are detected at those nodes by processing of the received signals. In an embodiment where the orthogonal signals are frequency orthogonal, spacing between the orthogonal frequencies, Dί, is at least the reciprocal of the measurement period T, the measurement period t being equal to the period during which the columns are sampled. Thus, in an embodiment, a column or antenna may be measured for one millisecond (T) using frequency spacing (Dί) of one kilohertz (i.e. , Dί = 1/t).

[0023] In an embodiment, the signal processor of a mixed signal integrated circuit (or a downstream component or software) is adapted to determine at least one value representing each frequency orthogonal signal transmitted to a row. In an embodiment, the signal processor of the mixed signal integrated circuit (or a downstream component or software) performs a Fourier transform to received signals. In an embodiment, the mixed signal integrated circuit is adapted to digitize received signals. In an embodiment, the mixed signal integrated circuit (or a downstream component or software) is adapted to digitize received signals and perform a discrete Fourier transform (DFT) on the digitized information. In an embodiment, the mixed signal integrated circuit (or a downstream component or software) is adapted to digitize received signals and perform a Fast Fourier transform (FFT) on the digitized information -- an FFT being one type of discrete Fourier transform.

[0024] It will be apparent to a person of skill in the art in view of this disclosure that a DFT, in essence, treats the sequence of digital samples (e.g., windows) taken during a sampling period (e.g., integration period) as though it repeats. As a consequence, signals that are not center frequencies (i.e., not integer multiples of the reciprocal of the integration period (which reciprocal defines the minimum frequency spacing)), may have relatively nominal, but unintended consequence of contributing small values into other DFT bins. Thus, it will also be apparent to a person of skill in the art in view of this disclosure that the term orthogonal as used herein is not “violated” by such small contributions. In other words, as we use the term frequency orthogonal herein, two signals are considered frequency orthogonal if substantially all of the contribution of one signal to the DFT bins is made to different DFT bins than substantially all of the contribution of the other signal. [0025] In an embodiment, received signals are sampled at at least 1 MHz. In an embodiment, received signals are sampled at at least 2 MHz. In an embodiment, received signals are sampled at 4 Mhz. In an embodiment, received signals are sampled at 4.096 Mhz. In an embodiment, received signals are sampled at more than 4 MHz. To achieve kHz sampling, for example, 4096 samples may be taken at 4.096 MHz. In such an embodiment, the integration period is 1 millisecond, which per the constraint that the frequency spacing should be greater than or equal to the reciprocal of the integration period provides a minimum frequency spacing of 1 KHz. (It will be apparent to one of skill in the art in view of this disclosure that taking 4096 samples at 4 MHz would yield an integration period slightly longer than a millisecond, and not achieve 1 kHz sampling, and a minimum frequency spacing of 976.5625 Hz.) In an embodiment, the frequency spacing is equal to the reciprocal of the integration period. In such an embodiment, the maximum frequency of a frequency orthogonal signal range should be less than 2 MHz. In such an embodiment, the practical maximum frequency of a frequency orthogonal signal range is preferably less than about 40% of the sampling rate, or about 1.6 MHz. In an embodiment, a DFT (which could be an FFT) is used to transform the digitized received signals into bins of information, each reflecting the frequency of a frequency orthogonal signal transmitted which may have been transmitted by the transmit antenna 130. In an embodiment 2048 bins correspond to frequencies from 1 KHz to about 2 MHz. It will be apparent to a person of skill in the art in view of this disclosure that these examples are simply that, exemplary. Depending on the needs of a system, and subject to the constraints described above, the sample rate may be increased or decreased, the integration period may be adjusted, the frequency range may be adjusted, etc.

[0026] In an embodiment, a DFT (which can be an FFT) output comprises a bin for each frequency orthogonal signal that is transmitted. In an embodiment, each DFT (which can be an FFT) bin comprises an in-phase (I) and quadrature (Q) component. In an embodiment, the sum of the squares of the I and Q components is used as a measure corresponding to signal strength for that bin. In an embodiment, the square root of the sum of the squares of the I and Q components is used as a measure corresponding to signal strength for that bin. It will be apparent to a person of skill in the art in view of this disclosure that a measure corresponding to the signal strength for a bin could be used as a measure related to activity, touch events, etc. In other words, the measure corresponding to signal strength in a given bin would change as a result of some activity proximate to the sensors, such as a touch event.

[0027] The sensing apparatuses discussed herein use transmitting and receiving antennas (also referred to herein as conductors, row conductors, column conductors, transmitting conductors, receiving conductors). However, it should be understood that whether the transmitting antennas or receiving antennas are functioning as a transmitter of signals, a receiver of signals, or both depends on context and the embodiment. In an embodiment, the transmitters and receivers for all or any combination of the patterns are operatively connected to a single integrated circuit capable of transmitting and receiving the required signals. In an embodiment, the transmitters and receivers are each operatively connected to a different integrated circuit capable of transmitting and receiving the required signals, respectively. In an embodiment, the transmitters and receivers for all or any combination of the patterns may be operatively connected to a group of integrated circuits, each capable of transmitting and receiving the required signals, and together sharing information necessary to such multiple 1C configuration. In an embodiment, where the capacity of the integrated circuit (i.e. , the number of transmit and receive channels) and the requirements of the patterns (i.e., the number of transmit and receive channels) permit, all of the transmitters and receivers for all of the multiple patterns used by a controller are operated by a common integrated circuit, or by a group of integrated circuits that have communications therebetween. In an embodiment, where the number of transmit or receive channels requires the use of multiple integrated circuits, the information from each circuit is combined in a separate system. In an embodiment, the separate system comprises a GPU and software for signal processing.

[0028] In an embodiment, the mixed signal integrated circuit is adapted to generate one or more signals and send the signals to the transmitting antennas via the transmitter. In an embodiment, the mixed signal integrated circuit is adapted to generate a plurality of frequency orthogonal signals and send the plurality of frequency orthogonal signals to the transmitting antennas. In an embodiment, the mixed signal integrated circuit is adapted to generate a plurality of frequency orthogonal signals and one or more of the plurality of frequency orthogonal signals to each of a plurality of transmit antennas. In an embodiment, the frequency orthogonal signals are in the range from DC up to about 2.5 GHz. In an embodiment, the frequency orthogonal signals are in the range from DC up to about 1.6 MHz. In an embodiment, the frequency orthogonal signals are in the range from 50 KHz to 200 KHz. The frequency spacing between the frequency orthogonal signals should be greater than or equal to the reciprocal of the integration period (i.e. , the sampling period).

[0029] The FMT sensors discussed above can be implemented into arrangements that are capable of providing different textures and feels while providing sensing capabilities. The sensors are able to determine touch events that occur above the surface of the sensor layer. Implementations of the sensor system are preferably adapted to determine pressure, hover, sense the location of and detection of various objects. [0030] FIG. 1 is a diagram of a layer arrangement for a sensor system 100. The sensor system 100 has a top layer 102 formed from polyurethane. Polyurethane materials are generally thermosetting, while some polyurethane materials are thermoelastic. Polyurethanes have been used for high resilience foams, skateboard wheels, synthetic fibers and paint finishes. Polyurethane has an elasticity/rigidity that is able to be adjusted with plasticizers and crosslinking. It should be understood that while polyurethane is discussed herein as a potential material for the external facing layer, other materials may be used in its stead that have similar properties as polyurethane. [0031] In the embodiment shown in FIG. 1 , the top layer 102 is approximately 1.0 mm. In an embodiment, the top layer is greater than 1.0 mm. In an embodiment the top layer is greater than 10 mm. In an embodiment, the top layer is less than 1.0 mm. The top layer may be between 0.1 mm and 10 mm. Thickness of the top layer may be determined based on the desired tactile feel of the sensor system 100.

[0032] Depending on the desired tactile feel the material and the thickness of the material may be changed. Other factors may also determine the material that is used for the top layer. For example, in an embodiment, the top layer is waterproof. In an embodiment, the top layer is deformable. In an embodiment, the top layer is able to return to its original shape after being compressed. In an embodiment, the top layer is soft. In an embodiment, the top layer has properties similar to that of human skin. In an embodiment, the top layer has properties substantially similar to that of human skin. In an embodiment, the top layer is formed from a composite matrix of material that has a biological composition that is grown so as to form the top layer.

[0033] It should be understood that when referring to the “top layer” it is generally meant that layer of material that will be exterior facing, and in the uses set forth herein, will be that layer that is subject to a touch event, including contact. For example, in a typical use a person may touch the top layer and that touch will be registered and measured by the sensor system.

[0034] Still referring to FIG. 1 , beneath the top layer 102 is an intermediate layer 104. The intermediate layer 104 in the embodiment shown in FIG. 1 is made of silicone rubber. Silicone rubber is cross-linked polydimethylsiloxane (PDMS). Silicone rubber has tunable mechanical properties. Silicone rubber is durable, cheap, moldable and non toxic. The intermediate layer 104 is adapted to be pliable and to compress upon receiving a force normal to its surface. Preferably the intermediate layer 104 is adapted to compress and then return to its original shape after the transmission of a compressive force. In an embodiment, the intermediate layer has properties similar, with respect to compression, to that of human skin. In an embodiment, the intermediate layer has properties substantially similar to that of human skin. In an embodiment, an intermediate layer includes metallic portions to enhance detection of non-conductive objects by the sensor system. In an embodiment, an intermediate layer includes conductive portions that enhance detection of non-conductive objects by the sensor system.

[0035] In the example shown in FIG. 1 , the intermediate layer 104 is approximately 1.0 cm. In an embodiment, the intermediate layer is greater than 1.0 cm. In an embodiment the intermediate layer is greater than 10 cm. In an embodiment, the intermediate layer is less than 1 cm. In an embodiment, the intermediate layer is 0.5 cm thick. The intermediate layer may be between 0.1 mm and 10 cm. Thickness of the intermediate layer may be determined based on the desired tactile feel of the sensor system 100.

[0036] Still referring to FIG. 1 , sensor layer 106 is formed beneath the top layer 102 and the intermediate layer 104. In an embodiment, the sensor layer 106 may be placed on other layers of material. The sensor layer 106 comprises a plurality of transmitting conductors and receiving conductors similar to those discussed above with respect to FMT sensors. Each transmitting conductor transmits a signal that is frequency orthogonal to each other signal transmitted. In an embodiment, the sensor layer is formed as row conductors and column conductors. In an embodiment, the sensor layer is formed as a matrix arrangement of transmitting antennas and receiving antennas. In an embodiment, the sensor layer is formed as a transmitting antenna and a plurality of receiving antennas. In an embodiment, the sensor layer is formed as a receiving antenna and a plurality of transmitting antennas. In an embodiment, the sensor layer is formed as transmitting antennas and receiving antennas wherein the roles of the respective transmitting antennas and receiving antennas alternate or dynamically change.

[0037] While reference is made to three layers in the discussion of the embodiment in FIG. 1 , it should be noted that there may be more than one intermediate layer or sensor layer. The top layer generally refers to the exterior facing layer, however the top layer may be formed of more than one layer of material that then forms the overall top layer. That is to say there may be more than one layer of material that is formed from the same material as the top layer. Further, there may be a plurality of layers that are placed over the sensor layer that are made of different materials in various possible arrangements, such as alternating layers of different materials or having different layers of material that are arranged in various layers.

[0038] Turning to FIG. 2 is a diagram of another exemplary layer arrangement for a sensor system 200. The sensor system 200 has a top layer 202 formed from polyurethane. In the example shown in FIG. 2, the top layer 202 is approximately 1.0 mm. In an embodiment, the top layer is greater than 1.0 mm. In an embodiment the top layer is greater than 10 mm. In an embodiment, the top layer is less than 1 mm. The top layer may be between 0.1 mm and 10 mm. Thickness of the top layer may be determined based on the desired tactile feel of the sensor system 200, similar to the top layer 102 discussed above with respect to FIG. 1 .

[0039] Still referring to FIG. 2, beneath the top layer 202 is an intermediate layer 204. The intermediate layer 204 in the embodiment shown in FIG. 2 is made of agar. Agar is a gelatinous material. Agar has a similar density to skin. The intermediate layer 204 is adapted to be pliable and to compress upon receiving a force normal to its surface. Preferably the intermediate layer 204 is adapted to compress and then return to its original shape after the transmission of the compressive force. The shape and feel of the intermediate layer 204 may be determined based on the same factors discussed above with respect to the intermediate layer of FIG. 1 .

[0040] In the example shown in FIG. 2, the intermediate layer 204 is approximately 1.0 cm. In an embodiment, the intermediate layer is greater than 1.0 cm. In an embodiment the intermediate layer is greater than 10 cm. In an embodiment, the intermediate layer is less than 1 cm. In an embodiment, the intermediate layer is 0.5 cm thick. The intermediate layer may be between 0.1 mm and 10 cm. Thickness of the intermediate layer may be determined based on the desired tactile feel of the sensor system 200.

[0041] Still referring to FIG. 2, sensor layer 206 is formed beneath the top layer 202 and the intermediate layer 204. The sensor layer 206 may be placed on other layers of material. The sensor layer 206 comprises a plurality of transmitting conductors and receiving conductors such as those discussed above and with reference to the FMT sensors. Each transmitting conductor transmits a signal that is frequency orthogonal to each other signal transmitted during an integration period. In an embodiment, the sensor layer is formed as row conductors and column conductors. In an embodiment, the sensor layer is formed as a matrix arrangement of transmitting antennas and receiving antennas. In an embodiment, the sensor layer is formed as a transmitting antenna and a plurality of receiving antennas. In an embodiment, the sensor layer is formed as a receiving antenna and a plurality of transmitting antennas. In an embodiment, the sensor layer is formed as transmitting antennas and receiving antennas wherein the roles of the respective transmitting antennas and receiving antennas alternate or dynamically change.

[0042] FIG. 3 is a diagram showing touch events on a sensor implementing orthogonal frequency division multiplexing sensing. In the sensing arrangement shown in FIG. 3 signals are transmitted on each of the transmitting antennas. Measurements of each of the signals received are used in order to determine touch events (represented by the circles). With respect to the embodiments discussed above and shown in FIGs. 1 and 2, touch events can be determined by detecting hover and then determining the impact of an approaching finger or object as it interacts with the sensor systems via the interaction with the transmitting antennas and receiving antennas.

[0043] FIG. 4 is a diagram showing touch events on a sensor wherein injection (infusion) is employed in the implementation in order to provide an additional ability to distinguish touch events. In the example shown in FIG. 4, a 254 kFIz sine wave is transmitted on an elastomer layer. Dual receiving conductors are used in both the vertical direction and the horizontal direction when a system of rows and columns is implemented. When using an infused signal, the measured signal due to force being applied to the elastomer layer is stronger due to the infused signal. The use of the infused signal in the elastomer layer may improve the ability of the system to determine touch events. In an embodiment, the infused signal is infused into the top layer of sensor systems as set forth in FIGs. 1 and 2 above. In embodiment, the infused signal is infused into the intermediate layer of sensor systems as set forth in FIGs. 1 and 2 above. In embodiment, the infused signal is infused into the intermediate layer and top layer of sensor systems as set forth in FIGs. 1 and 2 above. In an embodiment, an infused signal is infused into the intermediate layer and another infused signal is transmitted into the top layer of sensor systems as set forth in FIGs. 1 and 2 above. In an embodiment, more than one infused signal is infused into the intermediate layer and more than one infused signal is transmitted into the top layer of sensor systems as set forth in FIGs. 1 and 2 above. In an embodiment, more than one infused signal is infused into the intermediate layer of sensor systems as set forth in FIGs. 1 and 2 above. In an embodiment, more than one infused signal is infused and is transmitted into the top layer of sensor systems as set forth in FIGs. 1 and 2 above. In an embodiment, there are multiple layers used for the sensor system and multiple signals are infused into the multiple layers.

[0044] FIG. 5 is a diagram of a sensor system showing touch events on a sensor using transmitting and receiving conductors. The sensor system in FIG. 5 additionally uses signal infusion in order to increase the ability of the sensor system to detect touch events. In the embodiment, depicted in FIG. 5, the frequencies of the signals used for traditional sensing and for infusion are about 100 kFIz apart. In an embodiment, each of the signals transmitted by the sensor system are frequency orthogonal to each other signal transmitted by the sensor system.

[0045] FIG. 6 shows a sensor system 600 that uses indium tin oxide (ITO) for the top layer 602. Intermediate layer 604 is silicone rubber. Sensor layer 606 forms the bottom layer. Silicone rubber is cross-linked polydimethylsiloxane (PDMS). Silicone rubber has tunable mechanical properties, is durable, cheap, moldable and non-toxic. The silicone rubber may be Ecoflex 00-10 with a shore hardness of 00-10. In the embodiment shown in FIG. 6, the top layer 602 is approximately 1.0 mm. In an embodiment, the top layer is greater than 1.0 mm. In an embodiment the top layer is greater than 10 mm. In an embodiment, the top layer is less than 1 mm. The top layer may be between 0.1 mm and 10 mm. Thickness of the top layer 602 may be determined based on the desired tactile feel of the sensor system 600. The thickness and tactile feel of the top layer 602 may be similar to those discussed above with respect to FIGs. 1 and 2.

[0046] In the example shown in FIG. 6, the intermediate layer 604 is approximately 1.0 cm. In an embodiment, the intermediate layer is greater than 1.0 cm. In an embodiment the intermediate layer is greater than 10 cm. In an embodiment, the intermediate layer is less than 1 cm. In an embodiment, the intermediate layer is 0.5 cm thick. The intermediate layer may be between 0.1 mm and 10 cm. Thickness of the intermediate layer 604 may be determined based on the desired tactile feel of the sensor system 600. The thickness and tactile feel of the intermediate layer 604 may be similar to those discussed above with respect to FIGs. 1 and 2.

[0047] FIG. 7 shows a sensor system 700 that uses a conductive fabric for the top layer 702. Intermediate layer 704 is silicone rubber. The silicone rubber may be Ecoflex 00-10 with a shore hardness of 00-10. Sensor layer 706 forms the bottom layer. In the embodiment shown in FIG. 7, the top layer 702 is approximately 1.0 mm. In an embodiment, the top layer is greater than 1.0 mm. In an embodiment the top layer is greater than 10 mm. In an embodiment, the top layer is less than 1 mm. The top layer may be between 0.1 mm and 10 mm. Thickness of the top layer 702 may be determined based on the desired tactile feel of the sensor system 700. The thickness and tactile feel of the top layer 702 may be similar to those discussed above with respect to FIGs. 1 , 2 and 6.

[0048] In the example shown in FIG. 7, the intermediate layer 704 is approximately 1.0 cm. In an embodiment, the intermediate layer is greater than 1.0 cm. In an embodiment the intermediate layer is greater than 10 cm. In an embodiment, the intermediate layer is less than 1 cm. In an embodiment, the intermediate layer is 0.5 cm thick. The intermediate layer may be between 0.1 mm and 10 cm. Thickness of the intermediate layer 704 may be determined based on the desired tactile feel of the sensor system 700. The thickness and tactile feel of the intermediate layer 704 may be similar to those discussed above with respect to FIGs. 1 , 2 and 6.

[0049] FIG. 8 shows an arrangement of a sensor system that uses ITO for the top layer. The diagram shows an arrangement of transmitting conductors and receiving conductors as providing the sensing layer. The layers implemented in the sensing system shown in FIG. 8 may be similar to the layers of the sensing systems discussed above. [0050] FIG. 9 shows an arrangement of a sensor system that uses conductive fabric for the top layer. The diagram shows a sensing arrangement for detecting infused signals. The conductive fabric has operably connected thereto a transmitting conductor for providing an infusion signal. The layers implemented in the sensing system shown in FIG. 9 may be similar to the layers of the sensing systems discussed above. [0051] FIG. 10 shows an arrangement of a sensor system that uses conductive fabric for the top layer. The diagram shows an arrangement of transmitting conductors and receiving conductors as providing the sensing layer. Additionally, the sensing diagram reflects the determination of infused signals. The conductive fabric has operably connected thereto a transmitting conductor for providing an infusion signal. The layers implemented in the sensing system shown in FIG. 10 may be similar to the layers of the sensing systems discussed above.

[0052] FIG. 11 shows an arrangement of a sensor system 1100 with a top layer 1102 formed from ITO and an intermediate layer 1104 formed from agar. In the embodiment shown in FIG. 11 the top layer 1102 is formed to have a 1 .0 mm thickness. In the embodiment shown in FIG. 11 the intermediate layer 1104 is formed to have a 1 .0 cm thickness. In the embodiment shown in FIG. 11 the sensor layer 1106 is formed to have a 0.1 mm thickness. The layers implemented in the sensing system 1100 shown in FIG. 11 may be similar to the layers of the sensing systems discussed above.

[0053] FIG. 12 shows an arrangement of a sensor system 1200 with a top layer 1202 formed of conductive fabric. The top layer 1202 is formed having a 1.0 mm thickness. The intermediate layer 1204 is formed with a layer of agar. The intermediate layer 1204 is formed with a thickness of 1.0 cm. In the embodiment shown in FIG. 12 the sensor layer 1206 is formed to have a 0.1 mm thickness. The layers implemented in the sensing system shown in FIG. 12 may be similar to the layers of the sensing systems discussed above.

[0054] FIG. 13 shows an arrangement of a sensor system 1300 with a top layer 1302 formed of ITO. The ITO layer may be ITO coated PET plastic. The ITO coated PET plastic sheet may be a 1 mm glass sheet formed with a clear conductive liquid/film with 10-15 ohms/sq inch. The top layer 1302 is formed having a 1 .0 mm thickness. The intermediate layer 1304 is formed with a layer of polyurethane foam. Polyurethane foam is a potential embodiment of polyurethane materials that can be used. The intermediate layer 1304 is formed with a thickness of 1.0 cm. In the embodiment shown in FIG. 13 the sensor layer 1306 is formed to have a 0.1 mm thickness. The layers implemented in the sensing system 1300 shown in FIG. 13 may be similar to the layers of the sensing systems discussed above.

[0055] FIG. 14 shows an arrangement of a sensor system 1400 with a top layer 1402 formed of conductive fabric. The knit conductive fabric may conduct on 1 ohm per foot. The top layer 1402 is formed having a 1.0 mm thickness. The intermediate layer 1404 is formed with a layer of polyurethane foam. The intermediate layer 1404 is formed with a thickness of 0.1 cm. In the embodiment shown in FIG. 14 the sensor layer 1406 is formed to have a 0.1 mm thickness. The layers implemented in the sensing system 1400 shown in FIG. 14 may be similar to the layers of the sensing systems discussed above.

[0056] An aspect of the disclosure is a sensor system. The sensor system comprising a top layer; an intermediate layer located adjacent the top layer wherein the intermediate layer is adapted to compress upon transmission of a force normal to a surface of the intermediate layer; a sensor layer located adjacent the intermediate layer, the sensor layer comprising; a plurality of transmitting conductors adapted to transmit a plurality of signals, each of the transmitted plurality of signals is adapted to be orthogonal to each other of the plurality of signals transmitted during an integration period; a plurality of receiving conductors adapted to receive at least one of the plurality of signals transmitted during the integration period; and a processor adapted to process measurements of received signals and determine a touch event occurring on the top layer based on measurements of the received signals at the sensor layer.

[0057] Another aspect of the disclosure is a sensor system. The sensor system comprising a top layer; a compressible intermediate layer located proximate to the top layer; a sensor layer located adjacent the intermediate layer, the sensor layer comprising; a plurality of transmitting conductors adapted to transmit a plurality of signals during an integration period, a plurality of receiving conductors adapted to receive at least one of the plurality of signals transmitted during the integration period; and a processor adapted to process measurements of received signals and capacitively determine a touch event occurring on the top layer based on measurements of the received signals at the sensor layer.

[0058] While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1 . A sensor system comprising: a top layer; an intermediate layer located adjacent the top layer wherein the intermediate layer is adapted to compress upon transmission of a force normal to a surface of the intermediate layer; a sensor layer located adjacent the intermediate layer, the sensor layer comprising; a plurality of transmitting conductors adapted to transmit a plurality of signals, each of the transmitted plurality of signals is adapted to be orthogonal to each other of the plurality of signals transmitted during an integration period; a plurality of receiving conductors adapted to receive at least one of the plurality of signals transmitted during the integration period; and a processor adapted to process measurements of received signals and determine a touch event occurring on the top layer based on measurements of the received signals at the sensor layer.

2. The sensor system of claim 1 , wherein each of the transmitted plurality of signals is adapted to be frequency orthogonal to each other of the transmitted plurality of signals during each integration period.

3. The sensor system of claim 1 , wherein the intermediate layer is thicker than the top layer.

4. The sensor system of claim 1 , wherein the intermediate layer comprises agar.

5. The sensor system of claim 1 , wherein the intermediate layer comprises silicone rubber.

6. The sensor system of claim 1 , wherein the top layer comprises conductive fabric.

7. The sensor system of claim 1 , wherein the top layer comprises polyurethane.

8. The sensor system of claim 7, wherein the intermediate layer comprises silicone rubber.

9. The sensor system of claim 7, wherein the intermediate layer comprises agar.

10. The sensor system of claim 1 , wherein the top layer comprises conductive fabric and the intermediate layer comprises silicone rubber.

11 . The sensor system of claim 1 , wherein the intermediate layer is adapted to have an infusion signal infused therein.

12. The sensor system of claim 1 , wherein the top layer is adapted to have an infusion signal infused therein.

13. The sensor system of claim 1 , wherein both the top layer and the intermediate layer are adapted to have an infusion signal infused therein.

14. A sensor system comprising: a top layer; a compressible intermediate layer located proximate to the top layer; a sensor layer located adjacent the intermediate layer, the sensor layer comprising; a plurality of transmitting conductors adapted to transmit a plurality of signals during an integration period, a plurality of receiving conductors adapted to receive at least one of the plurality of signals transmitted during the integration period; and a processor adapted to process measurements of received signals and capacitively determine a touch event occurring on the top layer based on measurements of the received signals at the sensor layer.

15. The sensor system of claim 14, wherein each of the transmitted plurality of signals is adapted to be orthogonal to each other of the plurality of signals transmitted during the integration period.

16. The sensor system of claim 14, wherein each of the transmitted plurality of signals is adapted to be frequency orthogonal to each other of the transmitted plurality of signals during each integration period.

17. The sensor system of claim 14, wherein the intermediate layer is thicker than the top layer.

18. The sensor system of claim 14, wherein the intermediate layer comprises agar.

19. The sensor system of claim 14, wherein the intermediate layer comprises silicone rubber.

20. The sensor system of claim 14, wherein the top layer comprises polyurethane and the intermediate layer comprises silicone rubber.