GB2628170A

GB2628170A - Touch-sensitive apparatus having a touch sensor and display element and method

Info

Publication number: GB2628170A
Application number: GB2303925.8A
Authority: GB
Inventors: Timothy Sleeman Peter
Original assignee: Touchnetix Ltd
Current assignee: Touchnetix Ltd
Priority date: 2023-03-17
Filing date: 2023-03-17
Publication date: 2024-09-18
Anticipated expiration: 2043-03-17
Also published as: EP4681054A1; WO2024194601A1; GB2628170B

Abstract

A touch sensitive apparatus including a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes; a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode; and a controller for controlling operations of the touch sensitive apparatus. The controller is configured to: during a first time period, apply a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, apply a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels. The first and second drive signals may be the substantially the same and may be periodic signals with the same period. The signals may be square wave signals.

Description

TITLE OF THE INVENTION

TOUCH-SENSITIVE APPARATUS HAVING A TOUCH SENSOR AND DISPLAY ELEMENT AND METHOD

BACKGROUND OF THE INVENTION

The present invention relates to the field of touch-sensitive apparatuses, and more particularly touch-sensitive apparatuses having touch sensors overlying a display screen to provide a touch-sensitive display (otherwise referred to as touch screen). In particular, embodiments of the invention relate to controlling the display operation and the touch-sensing operation of such a touch-sensitive apparatus.

A capacitive touch sensor can be generalised as one that uses a physical sensor element comprising an arrangement of electrically conductive electrodes extending over a touch sensitive area (sensing area) to define sensor nodes and a measurement circuitry connected to the electrodes and operable to measure changes in the electrical capacitance of each of the electrodes or the mutual-capacitance between combinations of the electrodes. There are advantages and disadvantages to both of the measurement techniques. Measuring the changes in the electrical capacitance of each of the electrodes (i.e., performing a so-called measurement of the "self-capacitance" of an electrode) generally provides a much stronger signal than measuring the mutual-capacitance between combinations of the electrodes. Owing to the relatively stronger signal, the self-capacitance measurement technique has also been shown to be suitable for detecting objects (e.g., a user's finger or a stylus) above the sensing area, i.e., not contacting the sensing area but at a position hovering above the sensing area). In some applications, it may be advantageous to implement the ability to detect an object above the sensing area, for instance to ensure suitable detection of the object in unstable environments (such as moving in a vehicle) or for providing different inputs, if the touch sensor is capable of distinguishing between a hovering object above the sensing area and an object in contact with the sensing area.

There are a variety of display screen technologies available, two of which are OLED (organic light-emitting diode) displays and LCDs (liquid crystal displays). OLED displays utilise an organic layer which, when subject to an electrical field, emits light. LCDs on the other hand utilise a backlight, the light of which is manipulated as it passes through a liquid crystal layer which itself may be controlled when subject to an electric field. In each case, displays are typically formed from a plurality of pixels (or display pixels) where each of the pixels may be individually addressed using a matrix of connecting wires. Generally, an electric field is formed between the corresponding electrodes of a given pixel and a common electrode, with the organic layer of the OLED display or the liquid crystal layer of the LCD arranged between the common electrode and the matrix of connecting wires. Typically, the display comprises a transparent cover layer through which the image generated by the display is able to be viewed by a user. The common electrode and/or the connecting wires may be arranged to reduce obstruction of the pixels when viewed through the cover layer, or they may be formed from an electrically conductive, transparent material.

There are benefits to integrating touch sensors and displays, such as the OLED displays and LCDs mentioned above. This may be in terms of manufacturing complexity of the integrated apparatus itself (where typically the electrodes of the touch sensor are sputtered over an insulator, such as the cover layer, of the display) or of the overall host apparatus that the integrated touch sensor and display is to be used (such as a mobile phone, laptop, etc.). In addition, the optical effects of the touch sensor electrodes can be more accurately accounted for and compensated for when integrating the touch sensor and display to therefore provide better visibility or optical performance of the integrated touch sensor and display.

However, when the aforementioned touch sensor is integrated with a display screen, electrical conditions imposed by the display screen's construction can impact the capacitive measurements obtained by the touch sensor, and this has been found to particularly be the case for touch sensors that operate using the self-capacitance measurement technique. For example, the electrodes of the touch sensor suffer a potentially large loading capacitance towards the system ground via these electrical wires of the display or the common electrode. The loading capacitance can often be in the range of hundreds to thousands of picofarads per electrode of the touch sensor. Considering that typical variations in the self-capacitance of an electrode are on the order of tens of picofarads in the presence / absence of an object, the loading capacitance is so high that detecting the absence / presence of an object at, and especially hovering above, the sensing area using self-capacitance measurements is practically unviable. For example, a combined touch sensor and display utilising a self-capacitance measurement technique that desires to detect an object (e.g., a finger) hovering above the sensing area at a height of several centimetres, any controller of the combined touch sensor and display would likely need to obtain an extrinsic signal-to-noise ratio (SNR) of well over 100 dB to reliably detect the hovering object (and in fact, for a large combined touch sensor and display, the loading capacitance may be particular high on the worst affected electrodes that the controller would likely need an extrinsic SNR as high as 120 dB). Such SNRs are beyond current architectures and methods, particularly when considering the scan speeds of a touch sensor (i.e., the time required to scan all electrodes).

Additionally, noise may also be generated in any self-capacitance measurements as a result of currents flowing in the conducting wires and / or common electrode that relate to the driving of the pixels (i.e., the generation of the electric field). When combined with the effect of the loading capacitance, this further increases the demands on the controller to reliably determine whether an object is present or absent.

Note, however, that systems that use mutual-capacitance measurements can be arranged to be virtually immune to such loading capacitances. Thus, one way to combat the above issues is to provide a combined touch sensor and display that utilises the mutual capacitance measurement technique. However, such systems are generally not capable of reliably detecting an object hovering above the sensing area.

Alternatively, another way to combat the above is to uses a driven shield electrode. Such systems are provided with a separate electrode that surrounds the electrodes of the touch sensor, typically as a planar conductor directly behind the electrodes of the touch sensor separated by an insulating layer. Typically, a voltage waveform that is a close facsimile of the drive signal applied to the electrodes of the touch sensor and that is substantially in-phase with the drive signal is applied to the driven shield electrode. In this way, the driven shield electrode acts as a buffer for the electrodes of the touch sensor, effectively neutralising the load capacitance that is now "behind" the driven shield. That is, the driven shield electrode drives the load capacitance (instead of the electrodes of the touch sensor) and is designed to do so with minimum distortion and phase shift. The electrodes of the touch sensor now cannot "feel" the effect of the load capacitance. While there still remains a capacitive coupling between the driven shield electrode and the electrodes of the touch sensor, critically there is no (or very little) current flow because there is an almost zero voltage difference between the two. In other words, a capacitance only permits current flow when there is a voltage difference. Thus, the driven shield electrode can act to effectively shield the electrodes of the touch sensor from the loading capacitance.

However, implementation of a driven shield electrode in a combined touch sensor and display acts against some of the main driving factors for integrating the touch sensor and display. For example, implementation of a driven shield electrode increases the number of parts and therefore manufacturing complexity and cost, and also may cause optical degradation as it is another component that is positioned between the source of the image (i.e., the pixels) and the output of the image (i.e., the cover / outer layer of the combined touch sensor and display).

There is, therefore, a desire to provide combined touch sensors and displays with the ability to more accurately detect the presence of objects hovering above the sensing area, without increasing manufacturing complexity and costs, and while maintaining good optical performance.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a touch sensitive apparatus including a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes; a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode; and a controller for controlling operations of the touch sensitive apparatus. The controller is configured to: during a first time period, apply a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, apply a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels.

According to a second aspect of the invention there is provided a system comprising the touch-sensitive apparatus of the first aspect and system control circuitry, the system control circuitry configured to receive a signal from the controller indicative of the presence of a touch detected by one or more of the touch electrodes based on the measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor and to cause the system to perform an action in response to receiving the signal from the controller.

According to a third aspect of the invention there is provided a method of operating a touch-sensitive apparatus, the touch-sensitive apparatus comprising a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes, a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode, and a controller for controlling operations of the touch sensitive apparatus. The method includes: during a first time period, applying a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, making a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, applying a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels.

It will be appreciated that features and aspects of the invention described above in relation to the first and other aspects of the invention are equally applicable to, and may be combined with, embodiments of the invention according to other aspects of the invention as appropriate, and not just in the specific combinations described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described by way of example only with reference to the following drawings in which: Figure 1 schematically illustrates a combined touch sensor and display element for use with a touch-sensitive apparatus in accordance with certain embodiments of the invention; Figure 2 schematically illustrates a touch-sensitive apparatus comprising a combined touch sensor and display element, a touch controller, a display controller and the electrical connections therebetween in accordance with certain embodiments of the invention; Figure 3 schematically illustrates a self-capacitance measurement mode of the touch sensitive-apparatus, specifically with a view to explaining the principles of self-capacitance measurements; Figure 4 schematically illustrates drive signals applied to the touch sensor electrodes or pixel-driving conductive elements of the touch-sensitive apparatus as a function of time; specifically showing the signals applied during a first time period and a second time period, in accordance with certain embodiments of the invention; Figure 5 schematically illustrates an example system which employs the touch sensitive apparatus of Figure 2 in accordance with certain embodiments of the invention; and Figure 6 illustrates a method for operating the touch-sensitive apparatus of Figure 2, in accordance with certain embodiments of the invention.

DETAILED DESCRIPTION

The present disclosure relates broadly to a touch sensitive apparatus comprising a touch sensor (which comprises an array of electrodes forming a touch sensitive surface) which overlies a display element (which comprises pixels and associated circuitry for driving the pixels to display an image). The touch sensitive apparatus is configured to perform self-capacitance measurements of the touch sensor electrodes. Self-capacitance measurements have been identified as being particularly suitable for establishing whether an object (such as a human finger) is provided hovering above the touch sensitive surface, i.e., not making contact with the touch sensitive apparatus. To help shield the touch sensor electrodes from any loading capacitance caused by the presence of the conductive elements of the display element (which includes a common electrode and pixel-driving conductive elements), which would otherwise dominate any self-capacitance measurements made, the present disclosure operates according to different time periods. In a first time period, the touch sensor electrodes are driven to perform self-capacitance measurements and, at the same time, the conductive elements of the display element are driven with the same, or substantially the same, drive signal. The conductive elements of the display element are therefore repurposed from their normal function (of causing an image to be displayed) during the first time period to act instead as a driven shield for the touch sensor electrodes. In this way, during the first time period, self-capacitance measurements may be made where the influence of the loading capacitance is reduced or negated, and thereby measurements with a vastly superior signal to noise ratio may be obtained. Moreover, because the conductive elements are repurposed, no separate driven shield electrode is present and therefore the manufacturing costs of the touch sensitive apparatus can be reduced, and any impact the separate driven shield electrode has on the optical properties of the touch sensitive apparatus is reduced. In a second time period, the conductive elements of the display are driven in accordance with conventional techniques for driving the pixels of the display to display an image. During the second time period, no self-capacitance measurements are made.

Accordingly, for touch sensitive apparatuses having a touch sensor element overlying a display element, self-capacitance measurements are able to reliably be performed without the necessity for a separate driven shield electrode.

Figures 1 and 2 schematically show aspects of the touch-sensitive apparatus 1 comprising a combined touch sensor and display element in accordance with the principals of the present disclosure. Figure 1 schematically shows a combined touch sensor and display element 100 in an exploded view. Figure 2 schematically shows the combined touch sensor and display element 100 in combination with the touch controller 130 and display controller 230 of the touch-sensitive apparatus 1, along with a schematic representation of the electrical connections therebetween.

The touch-sensitive apparatus 1 is herein the combination of the combined touch sensor element and display 100, the touch controller 130 and display controller 230. Although the touch controller 130 and display controller 230 are shown as separate components in Figure 2, it should be appreciated that the touch controller 130 and display controller 230 may in other implementations be integrally formed. The touch controller 130 and display controller 230 may collectively be referred to as the controller of the touch sensitive apparatus 1, where the controller is generally responsible for controlling various operations of the touch-sensitive apparatus 1. It should also be appreciated that the touch-sensitive apparatus 1 may comprise other components, such as a power source and / or a communication mechanism for communicating with a host system, but these are omitted from Figures 1 and 2 for convenience.

Turning to Figure 1 first, Figure 1 is a highly schematic view of the combined touch sensor and display element 100 shown in an exploded view. The combined touch sensor and display element 100 is formed in a stacked arrangement having a plurality of layers, described in more detail below. More specifically, Figure 1 shows a combined touch sensor and display element 100 having an active matrix OLED display, referred to as an AMOLED display, and the following discussion will focus on the AMOLED display as the display element of the combined touch sensor and display element 100. However, it should be appreciated that the principles of the present disclosure are not limited to AMOLED as a display but may be applied to, e.g., passive matrix OLED displays, PMOLED, microLED displays, as well as to other active and passive matrix displays, such as active or passive LCDs.

The combined touch sensor and display element 100 comprises a substrate layer 140, a first cover layer 150, an organic emissive layer 160, a first insulator layer 170, a second insulator layer 180, and a second cover layer or outer cover layer 190. The plurality of layers are arranged or orientated such that the direction from the substrate layer 140 to the outer cover layer 190 defines an axis along which a user generally views the combined touch sensor and display element 100. That is to say, during use, the outer cover layer 190 is the layer that is closest to the user / user's eyes, with the substrate layer 140 typically being the layer that is furthest from the user / user's eye.

Throughout the discussion below, reference is made to the orientation of Figure 1 to describe the stacked arrangement of the various layers. The terms "on top of or "below" may be used to describe the relative position of one layer with respect to another in the stacked arrangement. However, it should be understood that these terms should not limit the orientation of the combined touch sensor and display element 100 in use. For example, the combined touch sensor and display element 100 may be arranged such that the normal (from the outer cover layer 190) is perpendicular to the direction along which gravity acts (e.g., as in a television or a computer screen) or parallel to the direction along which gravity acts (e.g., as in the surface of a table-top or the like). Indeed, the combined touch sensor and display element 100 may be oriented in any desired orientation depending on the application at hand.

Additionally, it should be appreciated that Figure 1 shows the plurality of layers in highly schematic form and certain aspects, such as the thicknesses of the layers or the areal extent of the layers, shown in the Figures should not be construed as limiting, and in practical implementations such properties of the layers may be different from that shown as appropriate.

The combined touch sensor and display element 100 is comprised of a plurality of layers that are joined, e.g., adhered or bonded, or otherwise arranged in a stacked arrangement to form a substantially unitary component. Although certain layers may be used dually for the purposes of sensing touches (or more generally objects) and for displaying an image, the combined touch sensor and display element 100 broadly comprises a touch sensor element comprising one or more touch sensor electrodes 101, 102 for sensing the presence of an object in proximity of the one or more touch sensor electrodes 101, 102, and a display or display element comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels (i.e., for causing the pixel to change its brightness and/or colour) and at least one common electrode.

The substrate layer 140 is generally provided as the first or base layer of the stack of layers forming the touch sensor and display element 100. The substrate layer 140 may be formed from any suitable material such as glass or a rigid polymer. The substrate 140 is formed from an electrically non-conductive material. For OLED display technology, the substrate layer 140 is typically formed from an opaque material, although the substrate layer 140 may be formed from a transparent material, if desired.

Figure 1 shows a plurality of pixel anodes 201 provided on the surface of the substrate layer 140. The pixel anodes 201 are electrically conductive elements, for example metal plates, which may be supplied with electrical current. The pixel anodes 201 are shown in a 4 x 4 grid arrangement in Figure 1, although it should be appreciated that in practical systems many more pixel anodes 201 may be provided. The pixel anodes 201 are provided for individually controlling pixels of the AMOLED display and thus typically the number of pixel anodes 201 corresponds to the number of pixels of the display (or vice versa). Although not shown in Figure 1, each of the pixel anodes 201 is provided with conductive wires that allow the display controller 230 to individually address ones of the pixel anodes 201 and supply an electrical current thereto. The conductive wires may be provided in a grid arrangement of horizontal and vertical wires extending across the surface of or within the substrate layer 140. The conductive wires may be called gate wires (e.g., the vertical wires or vice versa) and data or source wires (e.g., the horizontal wires or vice versa). Broadly, at the intersections of the grid of conductive wires, a thin film transistor, TFT, is provided. The gate of the TFT is coupled to and controlled by signals provided along the conductive gate wires by the display controller 230, which causes an electrical current supplied along the source wires coupled to the source of the TFT to charge the corresponding pixel anode 201 coupled to the drain of the TFT. As will be described below, the pixel anode 201 forms a part of a capacitor which is subsequently capable of generating a flow of electrical current between the pixel anode 201 and a cathode 202.

It should therefore be appreciated that each pixel anode 201 is electrically coupled to a TFT such that each pixel anode 201 can be supplied with an electrical current to form an electric field with a cathode 202 to drive the corresponding pixels of the display. Moreover, the pixel anode 201 is arranged to be charged more quickly than it discharges. This means that individual pulses of current may be supplied to each TFT of a shorter duration that the duration that each pixel anode 201 is capable of driving a pixel of the display as pixel anode 201 discharges. This allows for the display controller 230 to address a plurality of pixel anodes 201 without compromising the output of a given pixel. Broadly speaking, this is the principle of active matrix control.

It should be appreciated that the configuration of the pixel anodes 201, conducting wires and TFTs may be modified from that described above in other implementations, in accordance with conventional techniques. For instance, the conducting wires may not be arranged in a horizontal/vertical grid, and / or the pixel anodes 201 may not be arranged in an evenly spaced grid.

The first cover layer 150 is arranged on top of the pixel anodes 201 and the substrate layer 140. That is to say, the pixel anodes 201 are provided sandwiched between the first cover layer 150 and the substrate layer 140. The first cover layer 150 is provided as a protective layer for the pixel anodes 201 and is formed of any suitable electrically non-conductive material. Depending on the implementation at hand, the first cover layer 150 may be omitted from the stack of layers of the combined touch sensor and display element 100. The organic emissive layer 160 is provided on top of the first cover layer 150. The organic emissive layer 160 is an organic or polymeric film which is arranged to convert electrical current into light. Any suitable organic or polymeric film may be provided, in accordance with conventional or known organic or polymeric films used in or suitable for use in OLED displays. In addition, the organic emissive layer 160 is shown as a single layer in Figure 1, but it should be understood that in other implementations, the organic emissive layer 160 may be formed from a plurality of elements arranged side-by-side to form the organic emissive layer 160. Each of the plurality of elements of the organic emissive layer may be the same or different, e.g., the elements may be configured to emit different light, i.e., different colours of light.

On top of the organic emissive layer 160 is shown a pixel cathode 202. The pixel cathode 202 is formed of an electrically conductive material, which may be the same or different material as the pixel anodes 201, and may be electrically connected to ground or a constant potential. The pixel cathode 202 is shown as a single electrically conductive material and is arranged so as to overlap each of the pixel anodes 201 when the organic emissive layer 160, cover layer 150 and substrate 140 are stacked. The pixel cathode 202 may therefore also be referred to as a common cathode 202. However, it should be appreciated that in other implementations, the pixel cathode 202 may comprise a plurality of electrically conductive elements (e.g., similar to the arrangement of the pixel anodes 201).

Each of the pixel anodes 201 is capable of establishing a capacitive coupling with the pixel cathode 202 when charged, and hence is capable of generating an electric field therebetween. In view of the above, it should be appreciated that the pixel anode 201 and the common cathode 202 sandwich the organic emissive layer 160. Therefore, the electric field formed between the pixel anode 201 and the common cathode 202 causes the region of the organic emissive layer 160 between the pixel anode 201 and the common cathode 202 to emit light dependent, in part, on the strength of the electric field generated (and hence the current flowing through the organic emissive layer 160). The common cathode 202 is arranged so as to permit light to pass through and / or around the common cathode 202. For example, the common cathode 202 may be formed from an electrically conductive and transparent material, such as Indium Tin Oxide (ITO).

The substrate layer 140 including the pixel anodes 201, the first cover layer 150, and the organic emissive layer 160 including the pixel cathode 202 form the display element of the combined touch sensor and display element 100. That is to say, these components, when controlled by a suitable controller, such as display controller 230, are configured to generate and output an image.

It should be appreciated that the above description has generally explained an example configuration of the components forming the display element of the combined touch sensor and display element 100, and in particular, in respect of an AMOLED display. Various modifications may be made to the display element of the combined touch sensor and display element 100 in accordance with known techniques. For example, additional and/or alternative layers may be provided in the stack of layers, such as additional insulators, colour filters, polarisers, electron/hole transport layers, etc. Additionally, the ordering of the layers may be different to that shown again in accordance with known techniques. For example, the pixel cathode 202 may instead be provided on the substrate layer 140 and the pixel anodes 201 on the organic emissive layer 160 (with suitable circuitry provided e.g., in an insulating layer). That is to say, in some implementations, the combined touch sensor and display element is configured as a stacked arrangement, whereby the one or more touch sensor electrodes 101, 102 are stacked on the plurality of pixel-driving conductive elements (i.e., the pixel anodes 201 and gate / source conducting wires 203, 205 described in respect of Figure 2 below), the plurality of pixel-driving conductive elements are stacked on the plurality of pixels (i.e., of the emissive layer 160), and the plurality of pixels are stacked on the at least one common electrode (i.e., the pixel cathode 202). In other implementations, the combined touch sensor and display element 100 is configured as a stacked arrangement, whereby the one or more touch sensor electrodes 101, 102 are stacked on the at least one common electrode (i.e., pixel cathode 202), the at least one common electrode is stacked on the plurality of pixels, and the plurality of pixels are stacked on the plurality of pixel-driving conductive elements (i.e., pixel anode 201 and gate / source conducting wires 203, 205).

It should be appreciated that although Figure 1 shows the stacked arrangement of the plurality of layers for an AMOLED display, the display element of the combined touch sensor and display element 100 is not limited to an AMOLED display. For example, in some implementations, a passive matrix OLED display, PMOLED display, may be used. In such a case, the pixel anodes 201 and pixel cathodes 202 are arranged in rows and columns respectively and the display controller 230 is configured to address individual pixels by application of a current to selected ones of the rows and columns. Alternatively, in some implementations, an active or passive matrix LCD, AMLCD or PMLCD respectively, may be used instead. For LCDs, the substrate layer 140 is typically transparent, as LCDs are typically provided with a backlight provided below the substrate layer 140 and arranged to transmit light through the stacked layers of the combined touch sensor and display element 100. In place of the organic emissive layer 160, a liquid crystal layer is provided. In effect, when the liquid crystal layer is exposed to an electric field, the liquid crystal layer varies its transmissibility, and subsequently light emitted from the backlight is transmitted through the liquid crystal layer to varying degrees. Hence, it should broadly be understood that the display element of the combined touch sensor and display element 100 may be implemented using any conventional display techniques known and the principles of the present disclosure are not particularly limited to any display technique.

Referring back to Figure 1, the first insulator layer 170, the second insulator layer 180, and the second cover layer or outer cover layer 190 generally form the touch sensor element of the combined touch sensor and display element 100.

The touch sensor element is primarily configured for establishing the position of a touch within a two-dimensional sensing area by providing Cartesian coordinates along an X-direction and a Y-direction. In this implementation, the first insulator layer 170 and second insulator layer 180 are formed from a glass or plastic or some other insulating material and upon which is arranged an array of electrodes consisting of multiple laterally extending parallel electrodes, X-electrodes 101 (row electrodes), and multiple vertically extending parallel electrodes, Y-electrodes 102 (column electrodes), which in combination allow the position of a touch to be determined. In the example shown, the Y-electrodes 102 are shown positioned on the surface of the first insulator later 170 and the X-electrodes 101 are shown positioned on the surface of the second insulator layer 180; however, it should be appreciated that the Y-electrodes 102 may instead be provided on the other (opposite) surface of the second insulator layer 180. Equally, the Y-electrodes 102 may be provided on the surface of the second insulator 180 and the X-electrodes 101 provided on the surface of the first insulator 170 (that is, either one of the X-electrodes 101 or Y-electrodes 102 may be provided closer to the outer cover layer 190). Collectively the X-electrodes 101 and Y-electrodes 102 are referred to herein as touch sensor electrodes 101, 102.

To clarify the terminology, and as will be seen from Figure 1, the X-electrodes 101 (row electrodes) are aligned parallel to the X-direction (the width direction of the second insulator layer 180) and the Y-electrodes 102 (column electrodes) are aligned parallel to the Y-direction (the length direction of the first insulator layer 170). Thus, the different X-electrodes 101 allow the position of a touch to be determined at different positions along the Y-direction while the different Y-electrodes 102 allow the position of a touch to be determined at different positions along the X-direction. That is to say in accordance with the terminology used herein, the electrodes are named (in terms of X-and Y-) after their direction of extent rather than the direction along which they resolve position. Furthermore, the electrodes may also be referred to as row electrodes and column electrodes. It will however be appreciated these terms are simply used as a convenient way of distinguishing the groups of electrodes extending in the different directions. In particular, the terms are not intended to indicate any specific electrode orientation. In general, the term "row" will be used to refer to electrodes extending in a horizontal direction for the orientations represented in the figures while the terms "column" will be used to refer to electrodes extending in a vertical direction in the orientations represented in the figures. The X-electrodes 101 and Y-electrodes 102 define a sensing (or sense) area, which is a region of the combined touch sensor and display element 100 which is sensitive to touch. In some cases, each electrode 101, 102 may have a more detailed structure than the simple "bar" structures represented in Figure 1, but the operating principles are broadly the same.

As can be seen in Figure 1, the first insulator layer 170 is provided on top of the organic emissive layer 160 and the pixel cathode 202. That is, the pixel cathode 202 is sandwiched between the first insulator layer 170 and the organic emissive layer 160. The first insulator layer 170 is formed of an electrically insulating material to prevent or reduce the pixel cathode 202 making direct electrical contact with the Y-electrodes 102 disposed on the surface of the first insulator layer 170. Additionally, the second insulator layer 180 is provided on top of the first insulator layer 170 and the Y-electrodes 102. That is, the Y-electrodes 102 are sandwiched between the first insulator layer 170 and the second insulator layer 180. The second insulator layer 180 is formed of an electrically insulating material to prevent or reduce the X-electrodes 101 making direct electrical contact with the Y-electrodes 102 disposed on the surface of the first insulator layer 170. Additionally, each of the first insulator 170 and the second insulator 180 are formed from electrically insulating, transparent materials such that light emitted from the organic emissive layer 160 is able to pass through the first insulator layer 170 and the second insulator layer 180. Additionally, the X-electrodes 101 and Y-electrodes 102 are arranged or configured to allow light to pass through or around the electrodes 101, 102. For example, the X-electrodes 101 and Y-electrodes 102 may be formed from an electrically conductive, transparent material, such as ITO.

In the described implementation, the X-and Y-electrodes 101, 102 are arranged on an orthogonal grid, generally with the X-electrodes on one side of the second insulator layer 180 and the Y-electrodes positioned on the opposite side of the second insulator layer 180 and oriented at substantially 90° to the X-electrodes 101. In other implementations, the electrodes may be oriented at a different angle (e.g., 30°) relative to one another. In addition, it should also be appreciated that it is also possible to provide structures where the grid of touch sensor electrodes 101, 102 is formed on a single side of the second insulator 180 and small conductive bridges are used to allow the two orthogonal sets of electrodes 101, 102 to cross each other without short circuiting. However, these designs are more complex to manufacture and less suitable for transparent second insulator layers 180. Regardless of the arrangement of the touch sensor electrodes 101, 102, broadly speaking, one set of electrodes is used to sense touch position in a first axis that we shall call "X" and the second set to sense the touch position in the second orthogonal axis that we shall call "Y".

Referring to Figure 2, the electrodes 101, 102 are electrically connected via circuit conductors 104a and 104b (collectively referred to as circuit conductors 104) to the touch controller 130. More specifically, the X-electrodes 101 are coupled via circuit conductors 104a to the touch controller 130 and the Y-electrodes 102 are coupled via circuit conductors 104b to the touch controller 130. The touch controller 130 comprises measurement circuitry or a measurement module 105, which is in turn connected to processing circuitry or processing module 106. Although the measurement circuitry and the processing circuitry are shown as integrally comprised in the touch controller 130 (i.e., being provided by the same (micro)controller, processor, ASIC or similar form of control chip), in other implementations the measurement circuitry 105 and / or the processing circuitry 106 may each be provided by a separate (micro)controller, processor, ASIC or similar form of control chip communicatively coupled to the touch controller 130 and/or each other.

Generally speaking, the measurement circuitry 105 is configured to perform capacitance measurements associated with the X-and Y-electrodes 101, 102 (described in more detail below). The measurement circuitry 105 comprises drive circuitry for generating electrical signals (impulses) for performing the capacitance measurements, as well as suitable circuitry for measuring the resultant signals from the electrodes 101, 102 (which are indicative of the measured capacitance of the electrodes 101, 102. The measurement circuitry 105 of the touch controller 130 outputs the capacitance measurements to the processing circuitry 106, which is arranged to perform processing using the capacitance measurements. The processing circuitry 106 may be configured to perform a number of functions, but at the very least is configured to determine when a touch, caused by an object such a human finger or a stylus coming into contact with, or hovering above, the sense area of the combined touch sensor and display element 100 with appropriate analysis of relative changes in the electrodes' measured capacitance / capacitive coupling. The processing circuitry 106, as in the described implementation, may also be configured to, with appropriate analysis of relative changes in the electrodes' measured capacitance / capacitive coupling, calculate a position corresponding to the position of the object touching or hovering above on the cover's surface as an XY coordinate.

Referring back to Figure 1, the outer cover layer 190 is arranged on top of the second insulator layer 180 and the X-electrodes 101. That is, the X-electrodes 101 are sandwiched between the outer cover layer 190 and the second insulator layer 180. The outer cover layer is provided to act as a protective cover for the combined touch sensor and display element 100, and is formed from a transparent material such as glass to allow the light emitted from the organic emissive layer 160 to exit the combined touch sensor and display element 100 and to pass to the user. It should be appreciated that a user or an object that directly touches the surface of the combined touch sensor and display element 100 does not generally make direct galvanic connection to the electrodes 101, 102. Rather, the touch influences the electric fields 110 that the measurement circuitry 105 generates using the electrodes 101, 102 (described in more detail below). In accordance with the present disclosure, a distinction is made between an object or touch directly contacting the surface of the combined touch sensor and display element 100 and an object or touch hovering above the surface of the combined touch sensor and display element 100. Typically, the way in which either of these objects are detected is substantially the same; however, as should be appreciated, the signal resulting from an object hovering above the surface of the combined touch sensor and display element 100 is likely to be relatively weaker than the signal resulting from an object directly touching the surface of the outer cover layer 190.

As described above, the touch-sensitive apparatus 1 of the present disclosure is configured to utilise the "self-capacitance" measurement technique to detect the presence or absence of an object directly contacting and/or hovering above the surface of the outer cover layer 190.

Reference is made to Figure 3. Figure 3 is a schematic top-down view of the combined touch sensor and display element 100 and associated circuitry. Figure 3 broadly shows only the components of the touch sensor element of the combined touch sensor and display element 100 for ease of reference, and is provided for the purposes of explaining the self-capacitance measurement technique. In particular, Figure 3 schematically shows the X-electrodes 101 and Y-electrodes 102 relative to the second insulator layer 180, along with the touch controller 130 electrically coupled thereto via circuit conductors 104.

In Figure 3, the drive circuitry of the measurement circuitry 105 is configured to generate and apply an electrical stimulus (drive signal) 113 to each of the touch sensor electrodes 101, 102 which will cause an electric field 110 to form around the corresponding touch sensor electrode 101, 102. This field 110 couples through the space around the corresponding electrode back to the measurement circuitry 105 via numerous conductive return paths that are part of the nearby circuitry of the combined touch sensor and display element 100 and the housing of the touch-sensitive apparatus 1 or the housing of any apparatus in which the touch-sensitive apparatus 1 is housed (shown schematically by reference numeral 114), or physical elements from the nearby surroundings (shown schematically by reference numeral 115), etc., so completing a capacitive circuit 116. The overall sum of return paths is typically referred to as the "free space return path" in an attempt to simplify an otherwise hard-to-visualize electric field distribution. The important point to realise is that the measurement circuitry 105 is only driving each electrode from a single explicit electrical terminal 117; the other terminal is the capacitive connection via this "free space return path". The capacitance measured by the measurement circuitry 105 is the "self-capacitance" of the corresponding electrode (and connected tracks) that is being driven relative to free space (or Earth as it is sometimes called), i.e. the "self-capacitance" of the relevant touch sensor electrode 101, 102.

Touching or approaching the electrode with a conductive object, such as a human finger 109, causes some of the field to couple via the finger 109 through the connected body 118, through free space and back to the measurement circuitry 105. This extra return path 119 can be relatively strong for large objects (such as the human body), and so can give a stronger coupling of the electrode's field back to the measurement circuitry 105; touching or approaching the electrode 101, 102 hence increases the self-capacitance of the electrode 101, 102. The measurement circuitry 105 is configured to sense this increase in capacitance.

The increase is strongly proportional to the area of the applied touch of the finger 109 and is normally weakly proportional to the touching body's size (the latter typically offering quite a strong coupling and therefore not being the dominant term in the sum of series connected capacitances). Moreover, as noted above, the increase in capacitance is also proportional to the distance of the conductive object hovering from the surface of the combined touch sensor and display element 100. That is, the further the object is from the surface of the combined touch sensor and display element 100 (and hence the touch sensor electrodes 101, 102), the smaller the increase in capacitance.

When the measurement circuitry 105 operates in accordance with the self-capacitance measuring technique, the measurement circuitry 105 can either drive each touch sensor electrode 101, 102 in turn (sequential) with appropriate switching of a single control channel (i.e., via a multiplexer) or it can drive them all in parallel with an appropriate number of separate control channels. In the former sequential case, any neighbouring electrodes to a driven electrode are sometimes grounded by the measurement circuitry 105 to prevent them becoming touch sensitive when they are not being sensed (remembering that all nearby capacitive return paths will influence the measured value of the actively driven electrode). In the case of the parallel drive scheme, the nature of the stimulus applied to all the electrodes is typically the same so that the instantaneous voltage on each electrode is approximately the same. The drive to each electrode is electrically separate so that the measurement circuitry 105 can discriminate changes on each electrode individually, but the driving stimulus in terms of voltage or current versus time, is the same. In this way, each electrode has minimal influence on its neighbours (the electrode-to-electrode capacitance is non-zero but its influence is only "felt" by the measurement circuitry 105 if there is a voltage difference between the electrodes).

Hence, it should be appreciated from the above that the combined touch sensor and display element 100 comprises a display element (i.e., broadly defined by the substrate layer 140 and pixel anodes 201, first cover layer 150, and organic emissive layer 160 and pixel cathode 202) and touch sensor element (i.e., broadly defined by the first insulator layer 170 and Y-electrodes 102, second insulator layer 180 and X-electrodes 101, and outer cover layer 190) which both operate utilising electrically conductive components, and additionally electrically conductive components which are arranged to generate electrical fields. As noted above, when the self-capacitance measurement technique is utilised to sense the presence of objects at or above the surface of the outer cover layer 190, the self-capacitance of a given electrode 101, 102 is highly influenced by surrounding elements of the touch sensitive apparatus 1 and/or the environment. Therefore, when the touch sensor electrodes 101, 102 are driven to sense the self-capacitance of the given touch sensor electrodes 101, 102, the touch sensor electrodes 101, 102 suffer a large loading capacitance towards the ground of the touch-sensitive apparatus 1 via the pixel anodes 201 and/or the pixel cathode 202, which as noted above may be in the range of hundreds to thousands of picofarads per touch sensor electrode 101, 102. This means that to reliably detect changes (increases) in capacitance caused by the presence of an object (such as a finger) contacting or hovering above the outer cover layer 190, a large signal-to-noise ratio is required to be obtained by the touch controller 130 / measurement circuitry 105. Additionally, when the pixel anodes 201 and pixel cathode 202 are driven by the display controller 230 to generate an electric field and subsequently drive a pixel of the organic emissive layer 160, the electric fields may also couple to the touch sensor electrodes 101, 102. When these touch sensor electrodes 101, 102 are also being driven to determine the self-capacitance of the given electrode, noise from the electric fields provided by the pixel anodes 201 and pixel cathodes 202 may also couple to electric fields 114 generated by the given touch sensor electrode 101, 102, and therefore further influences the signal-to-noise ratio obtained by the touch controller 130 / measurement circuitry 105.

Hence, in accordance with the present disclosure, a touch-sensitive apparatus 1 and a technique for controlling the touch-sensitive apparatus 1 without the use of a dedicated driven shield electrode (e.g., a metallic or conductive layer provided between the pixel cathode 202 and Y-electrodes 102) and capable of detecting increases in self-capacitance of driven touch sensor electrodes 101, 102 is provided. In particular, the present disclosure describes a touch-sensitive apparatus 1 that is arrange to drive the touch sensor electrodes 101, 102 for sensing an increase in the self-capacitance of given touch sensor electrodes 101, 102 in a first time period and to drive the pixel anode(s) 201 and pixel cathode 202 for displaying an image via the organic emissive layer 160 in a second time period, distinct from the first time period. However, during the first time period, the touch-sensitive apparatus 1 is configured to drive either one, or both of, the pixel anodes 201 and pixel cathodes 202 (and any other associated conductive elements) with a drive signal that is the same or substantially the same as the drive signal used to drive ones of the touch sensor electrodes 101, 102. In other words, during the first time period when the touch-sensitive apparatus 1 is arranged to drive the touch sensor electrodes 101, 102 to sense changes in the self-capacitance thereof, the touch-sensitive apparatus 1 is configured to drive one or both of the pixel anodes 201 and pixel cathodes 202 to act as a driven shield electrode, thereby preventing the touch sensor electrodes 101, 102 from "feeling" the effect of the loading capacitance. The pixel anodes 201 and/or pixel cathodes 202 are repurposed during the first time period to act as the driven shield electrode. In this way, a dedicated driven shield electrode is not required, and the manufacturing complexity and cost of the touch-sensitive apparatus 1 can be reduced.

Reference is made to Figure 2. Figure 2 schematically shows the combined sensor and display element 100 in combination with the touch controller 130 and display controller 230 of the touch-sensitive apparatus 1. Figure 2 schematically shows one X-electrode 101 and one Y-electrode 102 of the touch sensor electrodes 101, 102. Additionally, Figure 2 schematically shows four pixel anodes 201a, 201b, 201c and 201d. It should be appreciated that the number of touch sensor electrodes 101, 102 and the number of pixel anodes 201a-201d is not limited to two and four respectively, and the principles of the present disclosure are applicable to touch-sensitive apparatuses having different numbers of touch sensor electrodes 101, 102 and pixel anodes 201a-201d.

Figure 2 shows the touch controller 130 (comprising the measurement circuitry 105 and processing circuitry 106). The touch controller 130 is electrically coupled to the X-electrode 101 by circuit conductor 104a (and there may be a corresponding number of circuit conductors 104a for each of the corresponding X-electrodes 101), and the touch controller is electrically coupled to the Y-electrode 102 by circuit conductor 104b (and there may be a corresponding number of circuit conductors 104b for each of the corresponding Y-electrodes 102). As noted above, the touch controller 130 may be configured to drive each of the electrodes 101, 102 simultaneously via separate channels, or a multiplexer may be used to sequentially couple ones of the touch electrodes 101, 102 to the touch controller 130.

Figure 2 shows the X-electrode 101 extending perpendicularly to, and overlapping a part of, the Y-electrode 102, although as described above, the touch sensor electrodes 101, 102 may be arranged differently.

Figure 2 shows the pixel anodes 201a to 201d, collectively pixel anodes 201, arranged in an equally spaced two-by-two grid. The pixel anodes 201 are shown corresponding to positions along the respective touch sensor electrodes 101, 102, with the exception of the fourth pixel anode 201d. However, it should be understood that the pixel anodes 201 may be arrange at any location with respect to the touch sensor electrodes 101, 102. It should also be appreciated that, generally, the touch sensor electrodes 101, 102 define a touch sensitive area capable of receiving a touch and therefore generally the pixel anodes 201 are likely to be present within the touch sensitive area defined by the touch sensor electrodes 101, 102 (although in other implementations the pixel anodes may extend outside the touch sensitive area defined by the touch sensor electrodes 101, 102).

Each of the pixel anodes 201a to 201d is shown diagrammatically coupled to gate conducting wires 203a, 203b, collectively gate conducting wires 203, and source conducting wires 205a, 205b, collectively source conducting wires 205. As noted above, for each pixel anode 201, a TFT (not shown in Figure 2) selectively couples a source conducting wire 205 to the pixel anode 201 based on signals sent to the gate of the TFT via the gate conducting wires 203. For example, in order to supply current to the pixel anode 201a, a suitable signal for controlling the gate of the TFT (i.e., for closing the gate of the TFT) is sent along the gate conducting wire 205a, while a current pulse is provided along source conducting wire 203a. It should be appreciated that by supplying signals to any of the gate conducting wires 203a, 203b and the source conducting wires 205a, 205b, any of the pixel anodes 201a to 201d may be supplied with current from the source conducting wires 203a, 203b. In this way, any of the pixel anodes 201a to 201d may be individually addressed and corresponding pixels of the organic emissive layer 160 may be individually controlled or activated based on the current supplied to the pixel anode 201a to 201d. The pixel anodes 201; gate conducting wires 203, and source conducting wires 205 may collectively be referred to herein as pixel-driving conductive elements as these are the components of the display element which cause the pixels to be driven.

The display controller 230 is configured to supply suitable signals to the various pixel anodes 201 for driving the pixels of the organic emissive layer 160. More specifically, the display controller 230 is configured to couple to the gate conducting wires 203 and the source conducting wires 205 to supply suitable gate control signals via the gate conducting wires 203 and suitable current pulses via the source conducting wires 205 for driving the pixel anodes 201. In Figure 2, the display controller 230 has four conducting wires 204a to 204d, collectively conducting wires 204, coupled to a first input, 0, of one of four switching apparatuses 131a to 131d. That is, each switching apparatus 131a to 131d has a first input 0 couple to a conducting wire 204 from the display controller 230 and an output coupled to one of the gate conducting wires 203 or source conducting wires 205. More specifically, a first switching apparatus 131a has a first input, 0, coupled to a first conducting wire 204a of the display controller 230 and an output coupled to the first gate conducting wire 203a. A second switching apparatus 131b has a first input, 0, coupled to a second conducting wire 204b of the display controller 230 and an output coupled to the second gate conducting wire 203a. A third switching apparatus 131c has a first input, 0, coupled to a third conducting wire 204c of the display controller 230 and an output coupled to the first source conducting wire 205a. A fourth switching apparatus 131d has a first input, 0, coupled to a fourth conducting wire 204b of the display controller 230 and an output coupled to the second source conducting wire 205a.

The switching apparatuses 131a to 131d will be described in more detail below; however, for the purposes of driving the pixels of the organic emissive layer 160, it should be understood that when the switching apparatuses 131a to 131d are controlled so as to couple the first input 0 to the output of the switching apparatuses 131a to 131d, the display controller 230 is capable of supplying signals to the gate conducting wires 203 and the source conducting wires 205. The display controller 230 may not supply signals to each of the conducting wires 203, 205 when the switching apparatuses 131a to 131d are controlled such that the first input 0 is coupled to the output, but the display controller 230 may supply signals to those conducting wires 203, 205 coupled to the specific pixel or pixels that are to be driven, for example, in accordance with a certain image to be displayed.

For completeness, Figure 2 also shows the pixel cathode 202 in highly schematic form as a series of horizontal and vertical wires coupled to one another. As described above, an electric field is able to be established between a given pixel anode 201a to 201d and the pixel cathode 202 to drive the corresponding pixel of the organic emissive layer 160. Further, it can be seen from Figure 2 that a fifth switching apparatus 131e is provided. The fifth switching apparatus 131e is substantially the same as switching apparatuses 131a to 131d; however, as can be seen, the switching apparatus 131e has a first input, 0, coupled to ground and an output coupled to the pixel cathode 202. Switching apparatus 131e is explained in more detail below, but it is to be understood that the switching apparatus 131e is capable of coupling the pixel cathode 202 to ground (or another fixed potential) when the first input, 0, is coupled to the output of the switching apparatus 131e. Collectively, switching apparatuses 131a to 131e are referred to herein as switching apparatuses 131.

Figure 2 further shows two additional conductive wires originating from the touch controller 130. In particular, the touch controller 130 comprises a display-driver conducting wire 132 and a switching apparatus control conducting wire 133. As can be seen in Figure 2, the display-driver conducting wire is coupled to the second inputs, I, of each of the switching apparatuses 131. Additionally, the switching apparatus control conducting wire 133 is schematically shown as extending to each of the switching apparatuses 131. As will be explained in more detail below, the touch controller 130 is configured to send a signal to the switching apparatuses 131a to 131e to cause the switching apparatuses 131a to 131e to switch between a state in which the first input, 0, is coupled to the output of the respective switching apparatus 131 and a state in which the second input, I, is coupled to the output of the respective switching apparatus 131 (and hence to the display-driver conducting wire 132).

The operation of the touch-sensitive apparatus 1 of Figures 1 and 2 will be described now with reference to Figure 4. Figure 4 is a graph showing a representation of three signals as a function of time. The x-axis of the graph of Figure 4 represents time in arbitrary units, while the y-axis of the graph represents the amplitude, in arbitrary units, of the various signals to be described. The top signal is representative of the switching apparatus control signal transmitted from the touch controller 130 along the switching apparatus control conducting wire 133 for controlling the state of the switching apparatuses 131. The middle signal is representative of the drive signal for driving the touch sensor electrodes 101, 102 for the purposes of detecting the self-capacitance of the touch sensor electrodes 101, 102. This drive signal for driving the touch sensor electrodes 101, 102 is transmitted from the touch controller 130 to one or more of the electrodes 101, 102 via the corresponding circuit conductors 104 and is additionally transmitted from the touch controller 130 to the second inputs, I, of the switching apparatuses 131 via the display-driver conducting wire 132. The bottom signal is representative of the signal applied to the gate conducting wires 203 and the source conducting wires 205.

As noted above, the touch-sensitive apparatus 1 of the present disclosure is configured obtain self-capacitance measurements of the touch sensor electrodes 101, 102 in a first time period and to drive pixels of the display element in a second time period. Figure 4 shows each of the first and second time periods and the various signals that are applied to the components of the touch-sensitive apparatus in each of the time periods.

At a time to as shown in Figure 4, the touch sensitive apparatus 1 is configured to begin obtaining self-capacitance measurements of the touch sensor electrodes 101, 102. At time tO, the touch controller 130 performs one of a number of actions to cause the touch sensitive apparatus 1 to begin obtaining self-capacitance measurements of the touch sensor electrodes 101, 102.

Firstly, the touch controller 130 is configured to output a switching apparatus control signal to the switching apparatus control conducting wire 133. The switching apparatus control signal is shown in the top part of Figure 4. As can be seen, the switching apparatus control signal is a square wave signal having a high output (during the period tO to t1) and a low output (during the period t1 to t2). In this implementation, when the switching apparatus control signal is high, each of the switching apparatuses 131a to 131e are controlled to be in a state where the second input, I, is coupled to the respective outputs of the switching apparatuses 131a to 131e. Accordingly, when in this state, signals that are applied to the second input, I, of the switching apparatuses 131a to 131d are subsequently provided to the gate conducting wires 203 and source conducting wires 205, and signals that are applied to the second input, I, of the switching apparatus 131e are subsequently provided to the pixel cathode 202.

Secondly, the touch controller 130 is configured to output a drive signal (e.g., the drive signal 113 of Figure 3) to one or more of the touch sensor electrodes 101, 102 via the corresponding circuit conductors 104 for obtaining measures of the self-capacitances of one or more of the touch sensor electrodes 101, 102. As described above, the touch controller may simultaneously output the drive signal to each of the touch sensor electrodes 101, 102 or sequentially output the drive signal to individual touch sensor electrodes 101, 102. The drive signal applied to the touch sensor electrodes 101, 102 is shown in the middle part of Figure 4, and in this implementation, during the period from tO to t1, the drive signal takes the form of a sinusoidal wave of a given frequency.

Thirdly, the touch controller 130 is configured to output the drive signal (e.g., the drive signal 113 of Figure 3) also to the second inputs, I, of the switching apparatuses 131a to 131e via the display-driver conducting wire 132. The drive signal applied to the second inputs of the switching apparatuses 131a to 131d and subsequently to the gate and source conducting wires 203, 205 is shown in the lower part of Figure 4, and in this implementation, during the period from tO to t1, the drive signal takes the form of a sinusoidal wave of a given frequency and is substantially the same as the drive signal applied to the touch sensor electrodes 101, 102 via the conducting wires 104. In addition, in this implementation, the drive signal is also applied to the second input of switching apparatus 131e and subsequently to the pixel cathode 202. Although this signal is not shown specifically in Figure 4, during the period from tO to t1, the drive signal takes the same form of a sinusoidal wave of a given frequency and is substantially the same as the drive signal applied to the touch sensor electrodes 101, 102 via the conducting wires 104.

The first time period is defined from the time tO to the time t1. During the first time period, the touch controller 130 continues to maintain the switching apparatuses 131a to 131e in the state where the second input, I, is coupled to the output, and to apply the drive signal to the touch sensor electrodes 101, 102 and the second inputs, I, of the switching apparatuses 131a to 131e. Accordingly, during the first time period, the touch controller 130 (or more particularly the measurement circuitry 105 thereof) is configured to obtain measurements of the self-capacitances of one or more of the touch sensor electrodes 101, 102 (substantially as described above with reference to Figure 3). In addition, the touch controller 130 is, in effect, configured to cause the pixel cathode 202 and pixel-driving conductive elements (i.e., the gate conductive wires 203, source conductive wires 205 and pixel anodes 201) to act as a driven shield electrode by applying the drive signal to the pixel cathode 202 and pixel-driving conductive elements.

Accordingly, because the pixel cathode 202 and pixel-driving conductive elements act as a driven shield electrode, when the touch controller 130 obtains the self-capacitance of the touch sensor electrodes 101, 102, the touch controller 130, in effect, does not feel the loading capacitance which would otherwise be present in the absence of driving the pixel cathode 202 and pixel-driving conductive elements as a driven shield electrode. Because the signal applied to the touch sensor electrodes 101, 102 and the pixel cathode 202 and pixel-driving conductive elements are substantially the same, there is no current flow between the touch sensor electrodes 101, 102 and the pixel cathode 202 and pixel-driving conductive elements (i.e., the gate conductive wires 203, source conductive wires 205 and/or pixel anodes 201). Accordingly, there is a significantly reduced amount of background capacitive loading and noise because the pixel cathode 202 and pixel-driving conductive elements are all helping to neutralise the loading capacitance. This means that the touch controller 130 can have a reduced requirement for signal-to-noise ratio (that is, the touch controller 130 is capable of obtaining signals with a generally higher signal-to-noise ratio, and can run at a higher measurement gain than would otherwise be possible). The touch controller 130 is therefore able to detect the relatively smaller capacitance changes caused by a conductive object near to (i.e., hovering above) the outer cover layer 190, as well as changes in capacitance caused by objects contacting the outer cover layer 190.

During the first time period, i.e., tO to t1, no updates to the pixels of the organic emissive layer 160 are made. That is to say, the pixel anodes 201a to 201d are not controlled to generate an electric field capable of driving the pixels of the organic emissive layer 160. Put simply, during the first time period, the image displayed by the organic emissive layer 160 remains stable. Note that because the pixel cathode 202, all the gate conductive wires 203, source conductive wires 205 and pixel anodes 201 are driven simultaneously during the first time period, only relatively small differential currents are generated in the organic emissive layer 160 (that is, pixel cathode 202, gate conductive wires 203, source conductive wires 205 and pixel anodes 201 are nominally equipotential) and hence the image generated by the organic emissive layer 160 will remain stable during the first time period. In this regard, in some implementations, the drive signal supplied by the touch controller 130 to the touch sensor electrodes 101, 102 and subsequently the drive signal supplied to the second inputs of the switching apparatuses 131 has a relatively low amplitude (e.g., in the range of a few volts or less, for example 2 Volts or less) so as not to exacerbate any differential currents caused by any small voltage offsets that are present in the touch sensitive apparatus 1, hence reducing the chance of any pixel disruption during the first time period.

At time t1, in other words after the first time period, the touch sensitive apparatus 1 is configured to perform image or pixel updates. In other words, during the second time period, which runs from t1 to t2 in Figure 4, the touch-sensitive apparatus 1 is configured to control the gate conductive wires 203, source conductive wires 205 and pixel anodes 201 (i.e., the pixel-driving conductive elements) to change or update the image displayed by the organic emissive layer 160 (on the assumption that such an image or the pixels thereof are indeed required to be changed). During the second time period, the touch controller 130 is configured to operate as follows.

Firstly, the touch controller 130 is configured to output the switching apparatus control signal to the switching apparatus control conducting wire 133. As can be seen in Figure 4, the switching apparatus control signal is a square wave signal having a low output (during the period t1 to t2, i.e., the second time period). In this implementation, when the switching apparatus control signal is low, each of the switching apparatuses 131 are controlled to be in a state where the first input, 0, is coupled to the respective outputs of the switching apparatuses 131. Accordingly, when in this state, signals that are applied to the first input, 0, of the switching apparatuses 131a to 131d are subsequently provided to the gate conducting wires 203, source conducting wires 205, and pixel anodes 201. In addition, when in this state, the first input, 0, of the switching apparatus 131e is coupled to ground (or other fixed potential), thereby coupling the pixel cathode 202 to ground (or other fixed potential).

Secondly, the touch controller 130 is configured to stop outputting a drive signal (e.g., the drive signal 113 of Figure 3) to one or more of the touch sensor electrodes 101, 102 via the corresponding circuit conductors 104. As can be seen in Figure 4, during the time period from t1 to t2, the drive signal applied to the touch sensor electrodes 101, 102 is a zero voltage signal (although, in other implementations, the drive signal may be a voltage signal at a constant level). Accordingly, during the second time period, the touch controller 130 (or more specifically the measurement circuitry 105 thereof) is configured to not make a measurement indicative of the self-capacitance of the one or more touch sensor electrodes 101, 102.

However, during the second time period, the display controller 230 is configured to output the relevant control signals to the gate conductive wires 203 and the source conductive wires 205 as described above. During the second time period, because the switching apparatuses 131a to 131d are in the state where the first input, 0, is coupled to the output of the switching apparatuses 131a to 131d, the display controller 230 is capable of causing the various control signals to be supplied to the TFTs of the corresponding pixel anodes 201a to 201d via the conductive wires 204a to 204d and the gate conductive wires 203 and the source conductive wires 205. The drive signals applied to the first inputs, 0, of the switching apparatuses 131a to 131d and subsequently to the gate and source conducting wires 203, 205 is shown in the lower part of Figure 4, and in this implementation, during the period from ti to t2, the drive signal is schematically represented by the shaded region of Figure 4. Note that the precise nature of the drive signals applied to the first inputs, 0, of the switching apparatuses 131a to 131d and subsequently to the gate and source conducting wires 203, 205 will depend on the image to be display and/or the pixels of the organic emissive layer 160 that require updating. For example, it may be the case that only pixel anode 201a requires updating in the period VI to t2 (i.e., the second time period), and therefore the display controller 230 outputs corresponding signals to circuit conductor 204a, switching apparatus 131a and gate conductive wire 203a and to circuit conductor 204c, switching apparatus 131c and source conductive wire 205a. In practice, it is expected that many of the pixels of the emissive layer 160 will require updating during the second time period, particularly when considering displays having a large display area and many pixels. Hence, it should be appreciated that the touch sensitive apparatus 1 is configured to perform self-capacitance measurements using the touch sensor electrodes 101, 102 during a first time period, and to perform display updates of the pixels of the emissive layer 160 during a second time period.

During the first time period, the various electrically conductive elements of the display element of the combined touch sensor and display element 100 (e.g., the pixel cathode 202, gate conductive wires 203, source conductive wires 205 and pixel anodes 201) are driven with a signal that is the same or substantially the same as the drive signal applied to the one or more touch sensor electrodes 101, 102 applied during the first time period. Therefore, the various electrically conductive elements of the display element of the combined touch sensor and display element 100 act as a driven shield electrode thereby leading to a greater possible signal to noise ratio for the obtained self-capacitance measurements of the touch sensor electrodes 101, 102. Equally, during the first time period, the display controller 230 is prevented from driving the pixel anodes 201 with signals for updating the pixels of the emissive layer 160. In other words, no updates to the pixels of the emissive layer 160 are performed during the first time period. The display controller 230 may be configured to identify when the touch-sensitive apparatus 1 is operating in the first time period and subsequently may be controlled to not output any signals for controlling the pixels of the emissive layer 160 on the conducting wires 204 during the first time period, or the display controller 230 may be configured to continually output signals for controlling the pixels of the emissive layer 160 on the conducting wires 204 and these signals are prevented from passing to the gate conducting wires 203 and the source conducting wires 205 by the switching apparatuses 131.

Conversely, during the second time period, the display controller 230 is permitted to drive the pixel anodes 201 with signals for updating the pixels of the emissive layer 160. In other words, updates to the pixels of the emissive layer 160 are permitted during the second time period. The display controller 230 may be configured to identify when the touch-sensitive apparatus 1 is operating in the second time period and subsequently may be controlled to output signals for controlling the pixels of the emissive layer 160 on the conducting wires 204 during the second time period, or the display controller 230 may be configured to continually output signals for controlling the pixels of the emissive layer 160 on the conducting wires 204 and these signals are subsequently able to pass to the gate conducting wires 203 and the source conducting wires 205 by the state of the switching apparatuses 131. During the second time period, the touch controller 130 is configured to drive the touch electrodes 101, 102 at a constant potential, either via coupling the electrodes to ground or by applying a DC voltage at a non-zero level. The touch controller 130 is configured to not make any self-capacitance measurements during the second time period.

The touch-sensitive apparatus 1 is configured to cyclically repeat operation according to the first time period and the second time period. That is, the first time period and the second time period together define a frame, where the first time period may be referred to as the "touch sub-frame" and the second time period may be referred to as the "display sub-frame", and wherein the touch sensitive apparatus 1 is configured to cyclically repeat a frame. Put another way, the touch controller 130 is configured to apply the drive signal to the one or more touch sensor electrodes 101, 102 of the touch sensor element of the combined touch sensor and display element 100 and additionally apply the drive signal to the pixel cathode 202 and pixel-driving conductive elements (i.e., pixel anodes 201 and gate / source conducting wires 203, 205) during a third time period (corresponding to a touch sub-frame) following the second time period, where during the third time period, the touch controller 103 is configured to make measurements indicative of the self-capacitance of the touch sensor electrodes 101, 102 as described above in respect of the first time period. A fourth time period, corresponding to the second time period (and hence a display sub-frame) follows the third time period, and so on.

In some implementations, the first and second time periods / sub-frames are set to a suitable duration to allow for the self-capacitance measurements of all the sensor electrodes 101, 102 to be obtained during the first time period, and for all the pixel updates to be performed in the second time period. However, in some implementations, this may not be practical and instead each sub-frame may be used to obtain a sub-set of the self-capacitance measurements and/or to perform a sub-set of the pixel updates. A longer first time period allows for either the self-capacitances of a greater number of touch electrodes 101, 102 to be measured or for a greater signal to nose ratio to be obtained for these electrodes 101, 102 that are measured (which is proportional to the duration of the obtained measurement). A longer second time period allows for relatively more pixels of the emissive layer 160 to be updated. However, in either case, the duration of the first/second time period may also dictate the responsiveness of the touch-sensitive apparatus 1. For example, if the second time period is relatively long, this means the time between successive first time periods, in which self-capacitance measurements are made, is also relatively long. This may mean that the touch-sensitive apparatus 1 may have a relatively slow response time to detecting a touch. For example, if a user touches the touch-sensitive apparatus 1 at the start of the second time period, the touch-sensitive apparatus 1 may not detect that touch until the second time period has elapsed. A similar situation may occur with a relatively long second time period, in which pixel updates are provided. In this case, the rate at which the pixels are update is relatively slower as pixel updates can only occur after the first time period has elapsed.

Hence, it should be appreciated that the duration of the first and second time periods may be set in accordance with particular desired performance characteristics of the touch-sensitive apparatus 1. In most practical systems, it is likely there will be a balance struck between the durations of the first and second time periods to allow for the self-capacitance measurements to be obtain and the pixel updates to be performed, without compromising the responsiveness and / or display update frequency of the touch-sensitive apparatus 1.

It has been described above that the drive signal applied to the touch sensor electrodes 101, 102 and to the pixel cathode 202 and pixel-driving conductive elements during the first time period is the same. However, it should be appreciated that the drive signal applied to the touch sensor electrodes 101, 102 need not be exactly the same as the drive signal applied to the pixel cathode 202 and pixel-driving conductive elements. The drive signals may be substantially the same. In some implementations, drive signal applied to the touch sensor electrodes 101, 102 (the first drive signal) is a periodic signal and the drive signal applied to the pixel cathode 202 and pixel-driving conductive elements (the second drive signal) is also a periodic signal having the same period as the first drive signal. In some implementations, the first drive signal is a sinusoidal wave of a first frequency, as described above, or alternatively may be square wave signal of the first frequency. Alternatively, other periodic signals, such as a train of pulses, may also be implemented.

In some implementations, the second drive signal is a square wave signal having the first frequency. When using a touch controller 130 that supplies a sinusoidal first drive signal to the touch sensor electrodes 101, 102, the switching apparatuses 131 used to switch between the output of the display controller 230 or ground (in the case of switching apparatus 131e) and the second drive signal being applied to the pixel cathode 202 and pixel-driving conductive elements may, in some implementations, normally be analogue types, which typically are more expensive. However, in other implementations, the switching apparatuses 131 may be replaced with more simple logic gates if the second drive signal is a square wave drive signal at the same phase and frequency as the first drive signal (i.e., the sinusoidal drive signal). In this case, the extent to which the loading capacitance is neutralised is a function of at least the amplitude of the fundamental frequency component of the square wave. The amplitude of the fundamental frequency component may be adjusted to optimise the extent to which the loading capacitance is neutralised, but in some practical implementations, only an approximate amplitude match will provide a suitable improvement in performance over a touch-sensitive apparatus 1 that does not utilise a driven shield.

While it has been described above that the touch-sensitive apparatus 1 comprises a combined touch sensor and display element 100 comprised of a plurality of layers that are joined, e.g., adhered or bonded, or otherwise arranged in a stacked arrangement to form a substantially unitary component, it should be appreciated that the principles of the present disclosure may be applicable to touch-sensitive apparatuses 1 having separately formed touch sensor elements and display elements provided in a stacked arrangement. That is, the touch sensor element and the display element need not be adhered or bonded to one another, and may be separately formed units that are stacked one above the other but configured to work together.

While it has been described above that the touch controller 130 causes the second drive signal to be applied to the pixel cathode 202 and the pixel-driving conductive elements (i.e., pixel anodes 201, and gate / source conducting wires 203, 205) during the first time period, it should be appreciated that in other implementations, the touch controller 130 may instead cause the second drive signal to be applied only to the pixel cathode 202 or only to the pixel-driving conductive elements. The circuitry shown in Figure 2 may be adapted accordingly. For example, in implementations where the pixel cathode 202 is driven with the second drive signal, the switching apparatus 131a to 131d may be omitted altogether or the respective first inputs, 0, may be coupled to ground or another fixed potential (instead of display-driver conducting wire 132). Equally, in implementations where the pixel-driving conductive elements are driven with the second drive signal, the switching apparatus 131e may be omitted altogether and the pixel cathode 202 may instead permanently be coupled to ground (or another fixed potential).

It should be appreciated that the circuitry shown in Figure 2 is an example configuration of a touch-sensitive apparatus 1 that is configured to apply the various signals described above. However, in other implementations, the circuitry may be configured differently to perform the same effect and/or additional elements may be present depending on the specific configuration -for example, there may be control circuitry providing which is suitable of coordinating the actions of the touch controller 130 and the display controller 230.

In addition, it has been described above that the touch-sensitive apparatus 1 obtains self-capacitance measurements according to the principles described above. However, the touch-sensitive apparatus 1 in some implementations is not restricted to making self-capacitance measurements of the sensor electrodes 101, 102. For example, in other implementations, the touch-sensitive apparatus 1 may additionally be configured to obtain measurements of the mutual capacitance between corresponding pairs of electrodes 101, 102.

In order to perform mutual capacitance measurements, the touch controller 130, or more specifically measurement circuitry 105, will sequentially stimulate each of the array of transmitter (driven/drive) electrodes, for example, the X electrodes 101, that are coupled by virtue of their proximity to an array of receiver electrodes, such as the Y electrodes 102 (although it should be appreciated that the Y electrodes 102 may instead be the transmitting electrodes and the X electrodes 101 may instead be the receiving electrodes in other implementations). The resulting electric field is now directly coupled from the transmitter electrode to each of the nearby receiver electrodes; the "free space" return path discussed above for self-capacitance measurements plays a negligible part in the overall coupling back to the measurement circuitry 105 when the combined touch sensor and display element 100 is not being touched. The area local to and centred on the intersection of a transmitter and a receiver electrode is typically referred to as a "node" or "intersection point". Now, on application or approach of a conductive element such as a human finger, the electric field is partly diverted to the touching object. An extra return path to the measurement circuitry 105 is now established via the body and "free-space" in a similar manner to that described above.

However, because this extra return path acts to couple the diverted field directly to the measurement circuitry 105, the amount of field coupled to the nearby receiver electrode decreases. This is measured by the measurement circuitry 105 as a decrease in the "mutual-capacitance" between that particular transmitter electrode and receiver electrodes in the vicinity of the touch 109. The measurement circuitry 105 senses this change in capacitance of one or more nodes.

Because the effect of the loading capacitance is minimal for mutual capacitance measurements of the touch sensor electrodes 101, 102, it is not necessary to provide a separate time period in which the mutual capacitance measurements are performed separately to the time period in which the pixels of the emissive layer 160 are updated. In other words, in some implementations, the during the second time period, the touch controller 130 is configured to drive the touch sensor electrodes 101, 102 so as to obtain measurements of the mutual capacitance while simultaneously the display controller 230 drives the pixel anodes 201 to perform pixel updates during the second time period. In this way, the touch-sensitive apparatus 1 is capable of obtaining both mutual capacitance measurements and self-capacitance measurements from the touch sensor electrodes 101, 102. In some implementations, however, the self-capacitance measurements pixel updates, and mutual capacitance measurements may be performed in separate time periods.

In addition, it should be understood that in some implementations, the touch-sensitive apparatus 1 may be configured to operate in accordance with different modes of operation.

For example, the touch-sensitive apparatus 1 may be configured to perform mutual capacitance measurements and display updates simultaneously and repeatedly, and only when suitable to do so, operate in accordance with the principles described above with respect to Figure 4, i.e., operate according to the first time period to obtain self-capacitance measurements and according to the second time period to perform display updates. This change in mode may be effected by a user input -i.e., selecting the ability to sense hovering objects.

Figure 5 is a highly schematic diagram showing the touch-sensitive apparatus 1 coupled to an associated system 602. The associated system 602 generally comprises system control circuitry, such as a computer processor which is capable of running a software application, and may also comprise other elements linked to the associated system 602 (e.g., such as elements for control or for performing certain functions). In some implementations, the touch sensitive apparatus 1 is integrally formed with the associated system 602, whereas in other implementations the touch sensitive apparatus 1 is able to be coupled to the associated system 602 e.g., via electrical cabling. For example, the associated system may be a smartphone, laptop, or the like.

The touch sensitive apparatus 1 functions as an input mechanism for the associated system 602. As mentioned, the processing circuitry 106 outputs a signal 600 indicating the presence of an object e.g., hovering above the outer cover layer 190 of the touch sensitive apparatus 1 to the associated system. In some applications, signal 600 may simply indicate whether or not an object has been detected, whereas in other instances, the signal 600 may indicate one or more positions of the object relative to the plane of the outer cover layer 190, for example as X, Y coordinates. The control circuitry of the associated system 602 may process the signal 600 in accordance with the application being run on the associated system, e.g., by causing the associated system to perform an action.

Figure 6 is a flow diagram showing the method for operating the touch-sensitive apparatus 1 according to aspects of the present disclosure.

The method assumes that the touch-sensitive apparatus 1 is operational (e.g., is turned on and provided with power). The method begins at step S1 where the touch controller 130 (or measurement circuitry 105 thereof) is configured to apply the first drive signal to the touch sensor electrodes 101, 102. As noted above, the first drive signal may be a sinusoidal signal of a first frequency, although any suitable periodic signal may be used.

The first drive signal is suitable for performing self-capacitance measurements of the one or more touch sensor electrodes 101, 102, and may be set accordingly. Furthermore, the touch controller 130 may be configured to simultaneously drive a plurality of the touch sensor electrodes 101, 102 with the first drive signal, or to sequentially drive individual ones of the touch sensors electrodes 101, 102, depending on the specific method by which the touch controller 130 is programmed to obtain the self-capacitance measurements.

At step S2, the touch controller 130 is configured to apply the second drive signal to the pixel cathode 202 and the pixel-driving conductive elements (i.e., the pixel anodes 201 and gate / source conductive wires 203, 205). Step S2 is performed simultaneously with step S1 such that the second drive signal is applied to the pixel cathode 202 and pixel-driving conductive elements at the same time as the first drive signal is applied to the touch sensor electrodes 101, 102. As noted above, the second drive signal may be the same, i.e., the same frequency, waveform and amplitude, or substantially the same as the first drive signal, e.g., it may have the same frequency but a different waveform and/or amplitude. As described above, the application of the second drive signal to the pixel cathode 202 and pixel-driving conductive elements causes the pixel cathode 202 and pixel-driving conductive elements to act as a driven shield, thereby shielding the touch sensor electrodes 101, 102 from any loading capacitances the touch sensor electrodes 101, 102 would otherwise experience.

At step S3, self-capacitance measurements are performed / obtained. This step involves the measurement circuitry 105 of the touch controller 130 receiving signals indicative of the self-capacitances of one or more sensor electrodes 101, 102. In this regard, the first drive signal and the second drive signal are applied for a first time period. The first time period may be set such that at least one self-capacitance measurement from at least one of the touch sensor electrodes 101, 102 is able to be obtained. The duration over which the self-capacitance measurement is made will influence the signal to noise ratio of the corresponding self-capacitance measurement, and therefore the first time period may be set so as to provide a suitable signal to noise ratio for the touch controller 130 (or more specifically the processing circuitry 106 thereof) to determine whether an object is able to be detected (i.e., whether the measurement reliably indicates an object on or above the cover layer 190). Multiple self-capacitance measurements may be made during the first time period.

At step S4, the touch controller 130 or associated control circuitry determines whether the first time period has elapsed. If not, i.e., NO at step S4, the method proceeds back to step S1, and steps S1 to S3 continue to be performed. If the first time period has elapsed, i.e., YES at step S4, the method proceeds to step S5.

Not shown in the method of Figure 6 is the processing that is performed on the self-capacitance measurements that are made at step S3. In this regard, once at least one self-capacitance measurement has been made, the measurement circuitry 105 may output the result of the self-capacitance measurement to the processing circuitry 106, where the processing circuitry 106 is adapted to determine when a change in the self-capacitance for a given sensor electrode 101, 102 exceeds a self-capacitance threshold. The self-capacitance threshold may be set to either indicate the presence of an object (e.g., a touch) at or on the outer cover layer 190 of the touch-sensitive apparatus 1 and/or to indicate the presence of an object above, i.e., hovering above, the outer cover layer 190 of the touch-sensitive apparatus 1. As noted above, the strength of the self-capacitive coupling between an object and a driven sensor electrode 101, 102 generally increases the closer the object is to the sensor electrode 101, 102; hence, the threshold or thresholds may be set appropriately. The threshold or thresholds may be set in advance and may be set differently for the given electrode of the sensor electrodes 101, 102. If the processing circuitry 106 determines at that the change in self-capacitance is greater than the threshold or thresholds, the processing circuitry 106 is configured to output a suitable signal (e.g., to the associated system) indicative of the sensed object. It should also be appreciated that the processing circuitry 106 may be configured to determine other characteristics of the object, such as its spatial position relative to the plane of the cover layer 190, e.g., by comparing the signals from pairs of the X-electrodes 101 and Y-electrodes 102.

Referring back to Figure 6, at step S5, a third drive signal is applied to the pixel-driving circuitry (i.e., the pixel anode 201, and gate / source conductive wires 203, 205) for a second time period. As should be appreciated, the third drive signal is applied by the display controller 230 to the pixel-driving circuitry and, as described above, the precise nature of the third drive signal will depend on the image to be displayed. Again, it should be appreciated that in practical implementations, the third drive signal will vary depending on which pixel the third drive signal is to be applied to. Equally, it is expected that the third drive signal will vary over the duration of the second time period depending on the pixels to be addressed. With reference to Figure 2, at the end of the first time period / start of the second time period, the touch controller 130 is configured to cause the switching apparatuses 131a to 131d to be in a state such that the signals from the display controller 230 are capable of being applied to the pixel-driving conductive elements. In addition, at step S5, the fifth switching apparatus 131e is configured to couple the pixel cathode 202 to ground (or another fixed potential).

At step S6, the touch controller 130 or associated control circuitry determines whether the second time period has elapsed. If not, i.e., NO at step S6, the method proceeds back to step S5, and the third drive signal is continued to be applied to the pixel-driving conductive elements. If the second time period has elapsed, i.e., YES at step S6, the method proceeds back to step S1 and the described method steps are repeated for a subsequent first time period, etc. While the above has described at step S2 that the second drive signal is applied to the pixel cathode 202 and the pixel-driving conductive elements (i.e., the pixel anode 201 and gate / source conductive wires 203, 205), it should be appreciated that in other implementations, the second drive signal may instead, be applied to either the common electrode (i.e., the pixel cathode 202) or the pixel-driving conductive elements. Suitable adaptations to the circuitry of the touch-sensitive apparatus 1 may be performed as desired.

Thus there has been described a touch sensitive apparatus including a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes; a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode; and a controller for controlling operations of the touch sensitive apparatus. The controller is configured to: during a first time period, apply a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, apply a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels. Also described is a system comprising a touch-sensitive apparatus and a method of operating a touch-sensitive apparatus.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.

Claims

CLAIMS1. A touch sensitive apparatus comprising: a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes, a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode, and a controller for controlling operations of the touch sensitive apparatus, wherein the controller is configured to: during a first time period, apply a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, apply a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels.
2. The touch-sensitive apparatus of claim 1, wherein the first drive signal and the second drive signal are substantially the same or the same.
3. The touch-sensitive apparatus of claim 1 or 2, wherein the first drive signal is a periodic signal and the second drive signal is a periodic signal having the same period as the first drive signal.
4. The touch-sensitive apparatus of any of the preceding claims, wherein the first drive signal is a sinusoidal or square wave signal having a first frequency.
5. The touch-sensitive apparatus of claim 4, wherein the second drive signal is a square wave signal having the first frequency.
6. The touch-sensitive apparatus of any of the preceding claims, wherein, during the second time period, the controller is configured to not make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor.
7. The touch-sensitive apparatus of any of the preceding claims, wherein, during the second time period, the one or more touch electrodes are each coupled to a constant voltage.
8. The touch-sensitive apparatus of any of the preceding claims, wherein the controller is configured to apply the first drive signal to the one or more touch electrodes of the touch sensor and the second drive signal to either of the plurality of pixel-driving conductive elements or the at least one common electrode during a third time period following the second time period, and during the third time period, make a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor.
9. The touch-sensitive apparatus of any of the preceding claims, wherein the touch-sensitive apparatus comprises a combined touch sensor element and display element, whereby the combined touch sensor element and display element comprises the one or more touch electrodes, the plurality of pixels, the plurality of pixel-driving conductive elements and the at least one common electrode.
10. The touch-sensitive apparatus of claim 9, wherein the combined touch sensor element and display element is configured as a stacked arrangement, whereby the one or more touch electrodes are stacked on the plurality of pixel-driving conductive elements, the plurality of pixel-driving conductive elements are stacked on the plurality of pixels, and the plurality of pixels are stacked on the at least one common electrode.
11. The touch-sensitive apparatus of claim 9, wherein the combined touch sensor element and display element is configured as a stacked arrangement, whereby the one or more touch electrodes are stacked on the at least one common electrode, the at least one common electrode is stacked on the plurality of pixels, and the plurality of pixels are stacked on the plurality of pixel-driving conductive elements.
12. The touch-sensitive apparatus of claim 10 or 11, wherein an insulating substrate is provided between the one or more touch electrodes and either of the plurality of pixel-driving conductive elements or the at least one common electrode.
13. The touch-sensitive apparatus of any of the preceding claims, wherein the display further comprises pixel-driving circuitry for applying the third drive signal to selected ones of the plurality of pixel-driving conductive elements, wherein the pixel-driving circuitry comprises a plurality of data lines each extending in a first direction and a plurality of scan lines each extending in a second direction, wherein the first direction is different from the second direction and the data lines are arranged to intersect the scan lines in a grid-type arrangement, and wherein a pixel-driving conductive element of the plurality of pixel-driving elements is electrically coupled to the intersection between a data line and a scan line.
14. The touch-sensitive apparatus of any of the preceding claims, wherein the display is a LCD or an OLED display.
15. A system comprising the touch-sensitive apparatus of any of the preceding claims and system control circuitry, the system control circuitry configured to receive a signal from the controller indicative of the presence of a touch detected by one or more of the touch electrodes based on the measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor and to cause the system to perform an action in response to receiving the signal from the controller.
16. A method of operating a touch-sensitive apparatus, the touch-sensitive apparatus comprising a touch sensor comprising one or more touch electrodes for sensing the presence of an object in proximity of the one or more touch electrodes, a display comprising a plurality of pixels, a plurality of pixel-driving conductive elements for driving the pixels and at least one common electrode, and a controller for controlling operations of the touch sensitive apparatus, wherein the method comprises: during a first time period, applying a first drive signal to the one or more touch electrodes of the touch sensor and a second drive signal to at least one of the plurality of pixel-driving conductive elements and the at least one common electrode, during the first time period, making a measurement indicative of the self-capacitance of the one or more touch electrodes of the touch sensor, and during a second time period, applying a third drive signal to one or more of the plurality of pixel-driving conductive elements to drive selected ones of the plurality of pixels.