Optical Capacitive Sensor

Abstract

The optical capacitance sensor (29) includes an input surface (30) and one or more light sources (31) arranged to illuminate a portion (35) of the input surface (30). The optical capacitance sensor (29) also includes an array (36) of optical capacitors (32) arranged to receive light (38) from the one or more light sources (31) that is reflected from an object (39) in contact with or proximity to the illuminated portion (35) of the input surface (30). The array (36) of optical capacitors (32) is configured to detect a reflection pattern of the object (39).

Description

[Technical Field]

[0001] The present invention relates to optical capacitance sensors, and more particularly to optical capacitance sensors for detecting patterns of reflected light. Optical capacitance sensors can be used for biometric authentication, such as detecting fingerprints or other distinctive patterns. Optical capacitance sensors can be incorporated into touchscreen display panels. [Background technology]

[0002] The photocapacitive effect is related to the change in space charge distribution of a material in response to illumination with light within a range of wavelengths. When the material is incorporated between the electrodes of a capacitor, the presence and / or intensity of illumination can be determined based on measuring the change in capacitance of the capacitor.

[0003] JC Anderson (1982) "Theory of photo-capacitance in amorphous silicon MIS structures", Philosophical Magazine B, 46:2, 151-161, 1982, DOI: 10.1080 / 13642818208246431 describes a theoretical treatment of the photo-capacitance effect in silicon metal-insulator-semiconductor (MIS) structures.

[0004] D. Caputo, G. de Cesare, A. Nascetti, F. Palma, and M. Petri, "Infrared photodetection at room temperature using photocapacitance in amorphous silicon structures," Appl. Phys. Lett. 72, 1229 (1998); https: / / doi.org / 10.1063 / 1.121022, describes a device based on amorphous silicon material that can detect infrared light by capacitance measurement at room temperature.

[0005] M. Tucci and D. Caputo, "Study of capacitance in hydrogenated amorphous silicon phototransistors for imaging arrays," Journal of Non-Crystalline Solids 338-340 (2004) 780-783, https: / / doi.org / 10.1016 / j.jnoncrysol.2004.03.090, describes a study of the capacitance of hydrogenated amorphous silicon phototransistors to determine their applicability for large-area imaging systems. Summary of the Invention

[0006] According to a first aspect of the present invention, there is provided an optical capacitance sensor including an input surface and one or more light sources arranged to illuminate a portion of the input surface. The optical capacitance sensor also includes an array of optical capacitors arranged to receive light from the one or more light sources reflected from an object in contact with or proximity to the illuminated portion of the input surface. The array of optical capacitors is configured to detect a reflection pattern of the object.

[0007] The reflection pattern may correspond to an albedo pattern, a color pattern, and / or a relief pattern. The reflection pattern may correspond to another pattern of a fingerprint and / or skin ridges.

[0008] The array of photocapacitors can be configured to detect fingerprints.

[0009] The pitch / spacing between the optical capacitors in the array may be less than 1 mm. The pitch / spacing between the optical capacitors in the array may be less than 0.5 mm. The pitch / spacing between the optical capacitors in the array may be small enough to resolve fingerprint ridges. The array of optical capacitors may be configured to detect a pattern of human skin ridges.

[0010] Each optical capacitor may include or be formed from a disordered crystalline or polycrystalline material. Each optical capacitor may include or be formed from a material containing trap states in the band gap of the material that can absorb subgap photon energy. Each optical capacitor may include or be formed from one or more of amorphous silicon, amorphous semiconductor oxide, organic material, etc.

[0011] The term "proximity" may refer to an object being close enough to the input surface so that the reflection pattern can be resolved given the pitch / spacing of the optical capacitors in the array. The maximum distance may depend, among other factors, on the dispersion of the light provided by the light source and the spatial frequency of the reflection pattern. For example, for reading fingerprints, photographs, documents, etc., proximity may refer to 1 mm or less for collimated or laser light sources and 0.1 mm or less for non-collimated light sources. For detecting fingertip or hand geometry, the distance may be greater, e.g., 100 mm or less for collimated or laser light sources and 10 mm or less for non-collimated light sources. For challenging applications, such as resolving subcutaneous tissue such as veins, proximity may refer to 0.5 mm or less for collimated or laser light sources.

[0012] Optical capacitance sensors can be implemented as passive sensors and / or as part of a passive sensing layer. Optical capacitance sensors can be implemented as active sensors and / or as part of an active sensing layer. Optical capacitance sensors can be implemented as part of buttons, touchpads, touch panels, touchscreen displays, etc.

[0013] An optical capacitance sensor may be operable when the input surface is wetted by and / or submerged in water or any other fluid that is transparent at the wavelengths emitted by the light source(s) and that the optical capacitor(s) can sense.

[0014] The one or more light sources may be directional and may emit light toward the input face. The one or more light sources may be disposed between the array of light condensers and the input face.

[0015] The array of optical capacitors can be disposed between the one or more light sources and the input surface. The optical capacitance sensor can also include a light-attenuating layer disposed between the one or more light sources and the array of optical capacitors. The light-attenuating layer can be configured to shield the optical capacitors from direct illumination by the one or more light sources within a wavelength range sensitive to the optical capacitors.

[0016] The light-attenuating layer may be patterned. The light-attenuating layer may be opaque and may substantially or completely block light. The light-attenuating layer may selectively block light and may take the form of a filter configured to block light within a range of wavelengths. The light-attenuating layer may take the form of a polarizer.

[0017] The one or more light sources may include one or more infrared emitters. The infrared emitters may include or take the form of light emitting diodes. The infrared emitters may be responsive to a peak emission in the range between (and including) 800 nm and 2,500 nm.

[0018] The one or more light sources may include one or more emitters selected from red, green, and blue emitters. The red emitter may include or take the form of a light emitting diode. The red emitter may correspond to a peak emission in the range between (and including) 700 nm and 635 nm.

[0019] The array of optical capacitors may include several first electrodes extending in a first direction and spaced apart in a second, different direction. The array of optical capacitors may include several second electrodes extending in a second direction and spaced apart in the first direction. The array of optical capacitors may include a layer of optical capacitive material disposed between first and second electrodes such that each intersection of the first and second electrodes provides an optical capacitor of the array.

[0020] The array of optical capacitors may include several first electrodes extending in a first direction and spaced apart in a second, different direction. The array of optical capacitors may include a plurality of second electrodes extending in a second direction and spaced apart in the first direction. The plurality of first electrodes and the plurality of second electrodes may be substantially coplanar and may be disposed on or above the layer of optical capacitive material such that each intersection of a first electrode and a second electrode provides an optical capacitor of the array.

[0021] The array of photocapacitors may include, in order, a number of first electrodes extending in a first direction and spaced apart in a second, different direction, a dielectric layer, a number of second electrodes extending in a second direction and spaced apart in the first direction, and a layer of photocapacitive material. The array of photocapacitors may include, in order, a layer of photocapacitive material, a number of first electrodes extending in a first direction and spaced apart in a second, different direction, a dielectric layer, and a number of second electrodes extending in a second direction and spaced apart in the first direction.

[0022] The array of optical capacitors may include several first electrodes extending in a first direction and spaced apart in a second, different direction. The array of optical capacitors may include a plurality of second electrodes extending in a second direction and spaced apart in the first direction. The plurality of first electrodes and the plurality of second electrodes may be substantially coplanar, and a layer of optical capacitive material may be substantially coplanar with the first and second electrodes and may be disposed in a gap separating the first and second electrodes.

[0023] The optical capacitance sensor may also include one or more conductive traces for projected capacitance measurements.

[0024] The display screen may include a cover lens and a display laminate. The display laminate may include an optical capacitive sensor according to the first aspect. The cover lens may provide an input surface.

[0025] The display laminate may include a backlight layer. The backlight layer may provide one or more light sources, or the backlight layer may include one or more light sources. The backlight layer may include one or more light sources and one or more additional light emitters. The backlight layer may be composed of one or more light sources.

[0026] The display laminate may include a pixel layer in the form of an array of light emitting diodes. The array of light emitting diodes may provide one or more light sources, or the array of light emitting diodes may include one or more light sources. The pixel layer may include one or more light sources and one or more additional light emitters. The pixel layer may be composed of one or more light sources.

[0027] The display stack may include a thin film transistor layer. The thin film transistor layer may provide or include an array of photocapacitors. A photocapacitance sensor may be implemented as part of the thin film transistor layer. The photocapacitance sensor may take the form of a thin film transistor having a source and drain shorted together to form a capacitor between the gate and the connected source and drain.

[0028] The display stack may include a thin film transistor layer and a separate photocapacitor layer, which may provide and / or define an array of photocapacitors.

[0029] The display stack may have a display area, and the (illuminated) portion of the input surface may correspond to a first region of the display area.

[0030] The display screen may also include a second optical capacitance sensor according to the first aspect, the second optical capacitance sensor being associated with a portion of the input surface corresponding to a second area of ​​the display area that is different from the first area.

[0031] The display laminate has a display area, and the (illuminated) portion of the input surface may substantially correspond to the display area. The (illuminated) portion of the input surface may substantially correspond to the display area if it corresponds to 90% or more of the display area.

[0032] The display laminate may include conductive traces for projected capacitive touch sensing.

[0033] The access control device may include an optical capacitance sensor or a display screen.

[0034] Access control devices can be used to operate equipment such as, for example, printers, medical equipment, doors, elevator (lift) control panels, automobiles, motorcycles, bicycles, construction equipment such as bulldozers, backhoes, excavators, aircraft, military equipment, etc. Access control devices can be used to operate equipment such as, for example, medicine cabinets, hospital wards such as obstetrics and delivery units, hotel guest room doors, hotel back doors, or any other room or space to which access is desired to be controlled.

[0035] The apparatus may include the optical capacitance sensor, a display screen, and / or an access control device as described above. The apparatus may also include a controller connected to the optical capacitance sensor and configured to measure the capacitance of the array of optical capacitors.

[0036] The controller may be further configured to measure an optical capacitance component of the capacitance of the array of optical capacitors.

[0037] The controller can be configured such that measuring the optical capacitance component includes measuring a capacitance of at least a subset of the array of optical capacitors. Measuring the optical capacitance component can also include determining an interaction area based on the capacitance of the subset of the array of optical capacitors.

[0038] Measuring the optical capacitance component may include deactivating each light source corresponding to the interaction area and measuring a projected capacitance component of each optical capacitor corresponding to the interaction area. Measuring the optical capacitance component may also include activating at least a subset of the light sources corresponding to the interaction area. Measuring the optical capacitance component may also include measuring a total capacitance of each optical capacitor corresponding to the interaction area. Measuring the optical capacitance component may also include determining the optical capacitance component corresponding to the interaction area based on a difference between the total capacitance and each projected capacitance component.

[0039] The subset of the array of light capacitors may include all of the light capacitors. The subset of light sources may include all of the light sources. The subset of light sources may include all light sources of a particular color. For example, a display may include red (R), green (G), and blue (B) pixels, and the projected capacitance component may be measured with all pixels inactive, followed by activating only the red (R) light source for measuring the total capacitance. In another example, the display may also include an IR light source over at least a portion of the display surface, and only the IR light source may be activated again for purposes of determining the light capacitance component.

[0040] The process of deactivating and activating the light sources can be repeated any number of times to refine the light volume components, for example, by averaging. If the light sources include more than one color, the process of deactivating and activating the light sources can be repeated one or more times to activate only one color of light source per total volume measurement. In this way, light volume components can be obtained independently for each different color of available light source.

[0041] The array of optical capacitors may take the form of intersections between a plurality of first electrodes and a plurality of second electrodes, as described above. In such a case, the controller may use a transmitter output to drive the first electrodes and a receiver input to monitor the second electrodes. Each transmitter output may provide a drive signal having a different frequency.

[0042] The controller may have a number of transmitter outputs fewer than the number of first electrodes, and each transmitter output may be connected to two or more first electrodes via a respective multiplexer. The outputs from the multiplexers may be connected to a spatially grouped subset of the first electrodes within the optical capacitance sensor. In other words, each transmitter output may be multiplexed to the first electrodes corresponding to a particular stripe or strip of the optical capacitance sensor corresponding to the subset of first electrodes. Alternatively, the outputs from the two or more multiplexers may be interleaved such that each first electrode within one or more spatially grouped subsets of first electrodes can be connected to a different transmitter output via a respective multiplexer. This latter option may allow all first electrodes within a particular stripe or strip of the optical capacitance sensor corresponding to the subset of first electrodes to be simultaneously activated for measurement.

[0043] The controller may have a smaller number of receiver inputs than the number of second electrodes, and the receiver inputs may be multiplexed to the second electrodes in any of the ways described with respect to the transmitter outputs and first electrodes.

[0044] The device may include a display screen, the display stack including conductive traces for projected capacitive touch sensing, and a controller connected to the conductive traces for projected capacitive touch sensing and to the optical capacitance sensor via a switch network, the controller may be configured to time-division multiplex the projected capacitance measurements from the conductive traces and the optical capacitance measurements from the optical capacitance sensor using the switch network.

[0045] The device may include a display screen, the display stack including conductive traces for projected capacitive touch sensing, a controller connected to the optical capacitance sensor and configured to measure the optical capacitance of the array of optical capacitors, and a dedicated touch controller connected to the conductive traces and configured for projected capacitive touch sensing using the conductive traces.

[0046] The device can be configured to, in response to detecting a user interaction using projected capacitance measurements, determine whether the user interaction corresponds to all or a portion of a user's hand in contact with the input surface. The device can be configured to, in response to determining that the user interaction corresponds to all or a portion of the user's hand, determine one or more fingerprint regions. The device can be configured to, in response to determining the one or more fingerprint regions, measure an optical capacitance corresponding to each fingerprint region.

[0047] The controller can store a reference frame corresponding to the measured capacitance of the array of optical capacitors when the one or more light sources are illuminated without an object above or in contact with the input surface. The controller can be further configured to subtract the reference frame from the measured capacitance from the array of optical capacitors.

[0048] The controller may be further configured to control the emission of light from the one or more light sources. Alternatively, the second controller may be configured to control the emission of light from the one or more light sources.

[0049] The device may be further configured such that in response to detecting a touch using projected capacitance, the controller measures the capacitance of the array of photocapacitors.

[0050] The device can also be configured such that, in response to detecting a touch using projected capacitance, the controller or a second controller causes one or more light sources to be illuminated and the controller measures the capacitance of the array of optical capacitors.

[0051] The one or more light sources may include one or more infrared light sources and one or more red light sources. The controller or the second controller may be configured to illuminate the infrared light sources and measure a first set of capacitances from the array of optical capacitors. The controller or the second controller may also be configured to illuminate the red light source and measure a second set of capacitances from the array of optical capacitors. The controller may be configured to compare the first set of capacitances and the second set of capacitances to determine whether an object above or in contact with the input surface corresponds to human skin.

[0052] The controller can be configured to determine whether an object above or in contact with the input surface corresponds to human skin by detecting differences in the reflection of infrared and red light consistent with oxygenated human tissue. In this manner, spoofing of sensors using fingerprint replication can be detected and prevented.

[0053] The controller may be further configured to control one or more infrared light sources and optical capacitance sensors to detect and / or image one or more veins contained in the object.

[0054] The device can be configured to compare the pattern of capacitance measured using the array to a set of one or more recognized patterns, and can be configured to output a signal in response to the pattern of capacitance measured using the array matching a recognized pattern of the one or more recognized patterns.

[0055] The comparison of the capacitance pattern to a set of one or more recognized patterns may be contingent on the measured capacitance pattern corresponding to an interaction area that exceeds a minimum area, and the size of the interaction area may be determined based on optical capacitance measurements obtained from an optical capacitance sensor and / or projected capacitance measurements obtained from the optical capacitance sensor and / or the conductive traces.

[0056] This condition can ensure that the comparison is based on a minimum area, which can help reduce false matches and improve security. If the device includes a display and the interaction area is insufficient for the comparison, the display can be controlled to display a message informing the user to reposition their finger (or palm, etc.) to allow for a more complete measurement.

[0057] The signals can activate equipment such as, for example, printers, medical devices, doors, elevator (lift) control panels, automobiles, motorcycles, bicycles, construction equipment such as bulldozers, backhoes, and excavators, aircraft, military equipment, etc. The signals can activate equipment such as, for example, medicine cabinets, hospital wards such as obstetrics and birthing units, hotel guest room doors, hotel back doors, or any other room or space to which access is desired to be controlled.

[0058] According to a second aspect of the present invention, there is provided a method of using an optical capacitance sensor, display screen, access control device and / or apparatus, the method comprising measuring the capacitance of an array of optical capacitors.

[0059] The method may include features corresponding to any feature of the optical capacitance sensor, the display screen, the access control device, and / or the apparatus.

[0060] The method may also include reading or obtaining a reference frame corresponding to the measured capacitance of the array of optical capacitors when the one or more light sources are illuminated without an object above or in contact with the input surface. The method may also include subtracting the reference frame from the measured capacitance using the array of optical capacitors.

[0061] The method may also include comparing the pattern of capacitance measured using the array to a set of one or more recognized patterns, and may also include outputting a signal in response to the pattern of capacitance measured using the array matching a recognized pattern of the one or more recognized patterns.

[0062] According to a third aspect of the present invention, there is provided an optical capacitance sensor comprising an input surface and an array of optical capacitors arranged to receive light from a light source transmitted through the input surface, the array of optical capacitors being configured to detect a laser point spot.

[0063] The configuration of the array of optical condensers configured to detect the laser point spot may correspond to a spacing between the array of between 1 mm and 5 mm (and inclusive).

[0064] The optical capacitance sensor of the third aspect may include features corresponding to any features of the optical capacitance sensor, display screen and / or device according to the first aspect and / or the method according to the second aspect.

[0065] According to a fourth aspect of the present invention, there is provided a system including an input surface. The system also includes one or more light sources arranged to illuminate a portion of the input surface. The system also includes an array of optical capacitors arranged to receive light from the one or more light sources reflected from an object in contact with or proximity to the illuminated portion of the input surface. The system also includes a controller configured to detect one or more touches based on projected capacitive scanning using the array of optical capacitors. The controller is also configured to obtain a fingerprint pattern corresponding to at least one of the one or more touches based on optical capacitance measurements obtained using the array of optical capacitors.

[0066] The system of the fourth aspect may include an optical capacitance sensor, a display screen and / or a device according to the first aspect, and / or features corresponding to any features of the method according to the second aspect.

[0067] The system may also include a display, and the system may be a touchscreen system.

[0068] The one or more light sources may include or take the form of one or more infrared light sources. The controller may be configured to pulse at least one of the infrared light sources during measurement of the corresponding light volume. The infrared light source may be a near-infrared light source. The term "strobe" may be used in place of the term "pulse."

[0069] Specific embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0070] [Figure 1] FIG. 1 is a schematic diagram of an optical capacitor. [Figure 2A] FIG. 2 is a schematic plan view of a mesh electrode. [Figure 2B] FIG. 2 is a schematic plan view of a frame electrode. [Figure 2C]FIG. 2 is a schematic plan view of a comb-shaped electrode. [Figure 2D] FIG. 2 is a schematic plan view of a serpentine electrode. [Figure 2E] FIG. 1 is a schematic plan view of a nanowire mat electrode. [Figure 2F] FIG. 2 is a schematic plan view of a pillar structure electrode. [Figure 2G] FIG. 2 is a schematic plan view of a transparent electrode. [Figure 2H] FIG. 2 is a schematic plan view of an opaque electrode. [Figure 2I] FIG. 2 is a schematic plan view of a porous electrode. [Figure 3] FIG. 2 is a diagram illustrating a first optical capacitance sensor. [Figure 4] FIG. 2 is a diagram illustrating a schematic diagram of an active sensing layer associated with a first optical capacitive sensor. [Figure 5] FIG. 10 is a diagram illustrating a second optical capacitance sensor. [Figure 6] FIG. 2 is a schematic cross-sectional view of a first display bottom laminate. [Figure 7] FIG. 10 is a schematic cross-sectional view of a second display bottom laminate. [Figure 8] FIG. 2 is a schematic cross-sectional view of a first on-cell laminate. [Figure 9] FIG. 2 is a schematic cross-sectional view of a second on-cell laminate. [Figure 10] FIG. 2 is a schematic cross-sectional view of a first in-cell laminate. [Figure 11] FIG. 10 is a schematic cross-sectional view of a second in-cell laminate. [Figure 12] FIG. 10 is a schematic cross-sectional view of a third on-cell laminate. [Figure 13] FIG. 10 is a schematic cross-sectional view of a fourth on-cell laminate. [Figure 14] FIG. 2 is a schematic plan view of a first display layout. [Figure 15] FIG. 10 is a schematic plan view of a second display layout. [Figure 16] FIG. 10 is a schematic plan view of a third display layout. [Figure 17] FIG. 10 is a schematic plan view of a fourth display layout. [Figure 18] FIG. 12 is a schematic cross-sectional view of a specific example of the second in-cell stack of FIG. 11. [Figure 19] FIG. 19 is a schematic cross-sectional view of the thin film transistor (TFT) integrated optical capacitor shown in FIG. [Figure 20] FIG. 1 illustrates a schematic diagram of a system for optical capacitive sensing. [Figure 21] FIG. 10 shows a schematic diagram of separate projected capacitive and optical capacitive readout configurations. [Figure 22A] FIG. 10 shows a schematic diagram of a projected capacitive and optical capacitive time-multiplexed readout configuration. [Figure 22B] FIG. 22B is a diagram illustrating a timing diagram of the time division multiplexed readout configuration shown in FIG. 22A. [Figure 23] FIG. 10 shows a schematic diagram of a combined projected capacitive and optical capacitive readout configuration. [Figure 24] FIG. 10 is a schematic cross-sectional view of a third optical capacitance sensor. [Figure 25] FIG. 10 is a schematic plan view of electrodes of a third optical capacitance sensor. [Figure 26] FIG. 10 is a diagram schematically illustrating electric field lines between electrodes of a third optical capacitance sensor. [Figure 27] FIG. 10 shows a schematic diagram of electric field lines between electrodes of a modification of the third optical capacitance sensor. [Figure 28] FIG. 24 is a schematic diagram of the interaction region, dark region, and measurement region of the combined readout configuration shown in FIG. 23. [Figure 29] FIG. 24 is a timing diagram illustrating the combined readout configuration shown in FIG. 23. [Figure 30] 29A and 29B are schematic diagrams illustrating measurements taken during different time periods shown in FIG. [Figure 31] FIG. 24 shows a schematic diagram of a first addressing scheme for implementing the combined readout configuration shown in FIG. 23; [Figure 32] FIG. 24 shows a schematic diagram of a second addressing scheme for implementing the combined readout configuration shown in FIG. 23; [Figure 33]1A-D are schematic diagrams illustrating corresponding measurement areas for projected capacitive sensing of the whole hand / palm and optical capacitive sensing. [Figure 34] 1A and 1B are diagrams illustrating schematic representations of relevant regions corresponding to user touches with different applied forces; [Figure 35] 1A and 1B are diagrams illustrating schematic representations of relevant regions corresponding to user touches with different applied forces; [Figure 36] 1A and 1B are diagrams illustrating schematic representations of relevant regions corresponding to user touches with different applied forces; [Figure 37] FIG. 10 is a schematic diagram of a presentation system including a fourth optical capacitive sensor. DETAILED DESCRIPTION OF THE INVENTION

[0071] In the following description, like parts are designated with like reference numerals.

[0072] Biometric authentication is increasingly being used for a variety of purposes, such as providing quick access to smartphones, tablets, and other devices. Biometric authentication can also be used within software applications, for example, to authenticate financial transactions. Other uses of biometric authentication are described below.

[0073] One existing technology is based on visible light reflection from, for example, a user's finger and subsequent fingerprint detection using a photodetector array. The fingerprint sensor is often located on or below a button separate from the display. For example, it would be desirable to locate the fingerprint sensor within the same area as the display to enable the use of fingerprint biometrics without sacrificing display area.

[0074] This specification relates to an optical capacitance sensor that can be used to provide an integrated in-display fingerprint reader for user / application authentication, among other applications described below. In contrast to prior art approaches based on optical detectors (e.g., photodiodes), this specification proposes using an array of optical capacitors that can detect light reflected from a pattern (e.g., a fingerprint) placed near or in contact with an input surface (e.g., a phone screen). The use of optical capacitors allows for greater flexibility in placing the pattern sensor within the display. For example, in some cases, infrared red (IR) reflection from a finger can be used, which is then detected by the optical capacitor array. This is advantageous in that most materials used in display modules have limited or reduced IR absorption, allowing for placement of the optical capacitor array at various heights within the display stack.

[0075] The spatial resolution of the optical capacitance sensor herein can be adjusted depending on the type of reflective pattern to be read. For example, to detect fingerprints using an integrated in-display array, optical capacitors can be placed at every (RGB) pixel or every R, ​​G, B sub-pixel. For high-resolution displays, the spatial scale of the pattern to be read determines the required resolution, so every nth pixel (n is a positive integer) may be sufficient.

[0076] Optical capacitance sensors according to the present disclosure can be used in conjunction with (or integrated with) capacitive touch sensing. A factor that can add flexibility with respect to the location of the optical capacitor is the non-simultaneous readout of capacitive touch and optical capacitance, as they are two different interaction modes.

[0077] Among other devices, optical capacitive sensors according to the present specification can be embedded into current display architectures that use embedded touch solutions, such as so-called "in-cell," "on-cell," "hybrid-in-cell" solutions, and / or future variations thereof.

[0078] light capacity Referring to FIG. 1, an optical capacitor 1 is shown.

[0079] The photocapacitor 1 includes a layer of photocapacitive material 2 between a first electrode 3 and a second electrode 4. The photocapacitive material 2 is a material that exhibits the photocapacitive effect. Without wishing to be bound by theory, a brief explanation of the photocapacitive effect is believed to be helpful in understanding the present specification.

[0080] Photocapacitance describes the change in charge state of a material 2 when exposed to light. This change in charge state is different from the so-called geometric capacitance, which is intrinsic to the material and can be considered as dark capacitance.

[0081] Photocapacitance can be observed in disordered materials where carrier traps dominate. Unlike crystals (or ordered materials), where a transfer from the valence band to the conduction band occurs in the presence of illumination (thereby generating a usable photocurrent), in disordered materials, illumination (wavelength / energy dependent) can induce the transfer of electrons from valence band states to localized trap states. These electrons remain trapped and at some point return to the valence band. During this period, there is no photocurrent due to the immobility of carriers in the trapped states, but there is a change in capacitance, which can be utilized as a means of detecting illumination.

[0082] The wavelength or energy of the incident radiation plays an important role in the electron migration dynamics that generate the photocapacitance. In disordered materials, localized, deep defect states may be distributed within the bandgap energy. For example, the bandgap of a-Si:H is 1.7 eV, while that of amorphous oxide semiconductors (AOS) can exceed 3 eV. When photons with energy smaller than the bandgap energy are incident on a disordered semiconductor, electrons or holes from extended (valence or conduction band) states may be excited to fill deep defect or tail states, defining a charge trapping process that changes the charge state and internal electric field distribution of the material. As mentioned previously, these trapped charges are fixed and therefore do not contribute to the photocurrent but instead contribute to the photocapacitance, which can be expressed as:

number

number

[0083] Additional capacity C photo can be measured in various ways, for example, device configurations in the form of passive capacitors (photocapacitors 1), transistors, diodes, or any other suitable circuits adapted, for example, from those deployed in the touch panel industry. Examples of implementation architectures are described below.

[0084] In terms of frequency response, the useful signal (i.e., C photo) can be obtained at low frequencies, e.g., a few hundred Hz, which is well above the frequency range where noise induced by electrostatic discharge, power supply noise, or any other form of low-frequency noise may be present. As the frequency increases, e.g., above a few kHz, the trap-ejection process disappears, and so an additional capacitance C photo may become difficult to measure or may disappear completely.

[0085] Material Considerations There are several irregular materials used in the flat panel industry that may be considered for use as the photocapacitive layer 2 of the photocapacitive sensor. Suitable materials do not include indium tin oxide, which is used as a passive transparent conductor.

[0086] Disordered materials are often used as the active layer in thin film transistors (TFTs), such as hydrogenated amorphous silicon (a-Si:H) (used herein as an example), followed by various organic semiconductors and, more recently, amorphous semiconductor oxides such as indium-gallium-zinc oxide (IGZO).

[0087] For example, a-Si:H is widely used in solar cells and photodiodes for visible light detection, and is the conventional material used in thin-film transistor (TFT) switches that form the basis of active-matrix liquid crystal displays (LCDs) or active-matrix organic light-emitting diode (AMOLED) displays. Notably, a-Si:H materials are highly disordered, resulting in a high concentration of distributed trap states. In fact, this is typically three to four orders of magnitude higher than that of amorphous oxide semiconductors (AOS). However, a-Si:H is a lower bandgap material, providing good absorption of visible radiation (absorption peaks primarily in the green) and the lower-energy near-infrared. In contrast, its AOS counterparts are high-bandgap materials that are generally transparent to visible light (absorption peaks in the deep blue and UV) but exhibit somewhat weaker absorption in the near-infrared, sufficient for photocapacitive response.

[0088] In contrast to the operating principle of photodetectors (e.g., photodiodes) and phototransistors, which rely on the generation of a photocurrent when a material is illuminated with visible light, the material's response to low-energy (long-wavelength) radiation is not due to a photocurrent, but rather to photocapacitance, where, instead of trapping charge (charge trapping), the material's disordered nature gives rise to trap states that are sufficient to absorb even low-energy radiation. The charge trap release process can accommodate the frequency of the stimulus signal used to measure capacitance, e.g., up to several kHz.

[0089] Photocapacitor electrodes The first electrode 3 and second electrode 4 used to form the photocapacitor 1 are not particularly limited, provided that they allow at least some incident light to reach the photocapacitive layer 2.

[0090] For example, and referring also to Figures 2A-2I, various possible electrode types are shown.

[0091] With particular reference to FIG. 2A, a mesh electrode 5 is shown.

[0092] The mesh electrode 5 may take the form of, for example, a conductive grid 6 formed of horizontal and vertical lines, leaving an array of gaps 7 through which light can pass into the photocapacitive layer 2. The conductive grid 6 may be formed from a metal or any other conductive material that can be processed to form a grid 6. Either or both of the first electrode 3 and the second electrode 4 may take the form of a mesh electrode 5.

[0093] With particular reference to FIG. 2B, the frame electrode 8 is shown.

[0094] The frame electrode 8 takes the form of a conductive strip 9 that follows the periphery of the photocapacitor 1, leaving an opening 10 through which light can pass to the photocapacitive layer 2. The conductive strip 9 may be formed from a metal or any other conductive material that can be treated to form the strip 9. Either or both of the first electrode 3 and the second electrode 4 may take the form of a frame electrode 8.

[0095] With particular reference to FIG. 2C, an interdigitated electrode 11 is shown.

[0096] Interdigitated electrode 11 takes the form of a first conductor 12 having an elongated region that interdigitates with an elongated region of a second conductor 13, leaving a serpentine gap 14. Conductors 12, 13 may be formed from metal or any other conductive material that can be processed to form conductors 12, 13. First conductor 12 and second conductor 13 may be connected to each other to form first electrode 3 or second electrode 4.

[0097] Alternatively, a first conductor 12 can provide the first electrode 3, a second conductor 13 can provide the second electrode 4, and a photocapacitive material 2 can fill the serpentine gap 14 to form a photocapacitor having a planar structure rather than a layered structure photocapacitor 1.

[0098] With particular reference to FIG. 2D, a serpentine electrode 15 is shown.

[0099] The serpentine electrode 15 takes the form of a conductive track 16 that follows a serpentine path, leaving openings 17 between parallel sections of the conductive track 16 through which light can pass to the photocapacitive layer 2. The conductive track 16 may be formed from a metal or any other conductive material that can be processed to form a conductive track 16. Either or both of the first electrode 3 and the second electrode 4 may take the form of a serpentine electrode 15.

[0100] With particular reference to FIG. 2E, a nanowire mat electrode 18 is shown.

[0101] Nanowire mat electrode 18 takes the form of a mat of conductive nanowires 19, dense enough to provide electrical conductivity to nanowire mat electrode 18, but not so dense and / or thick as to block light from reaching photocapacitive layer 2. Conductive nanowires 19 may be metal nanowires, carbon nanotubes (single-walled or multi-walled), or any other suitable conductive nanowires. Either or both of first electrode 3 and second electrode 4 may take the form of nanowire mat electrode 18.

[0102] With particular reference to FIG. 2F, a pillar structure electrode 20 is shown.

[0103] The pillar structure electrode 20 takes the form of a transparent conductive material patterned into a regular or irregular array of rods / columns / pillars 21. Any transparent conductive material can be used, such as indium tin oxide (ITO). Either or both of the first electrode 3 and the second electrode 4 may take the form of a pillar structure electrode 20. If the pillars 21 of the first electrode 3 and the second electrode 4 extend towards each other in an interpenetrating manner, the capacitance can be increased.

[0104] With particular reference to FIG. 2G, a transparent electrode 22 is shown.

[0105] The transparent electrode 22 takes the form of a continuous region of transparent conductive material, for example ITO 23. Either or both of the first electrode 3 and second electrode 4 may take the form of a transparent electrode 22.

[0106] With particular reference to FIG. 2H, the opaque electrode 24 is shown.

[0107] The opaque electrode 24 takes the form of a continuous region 25 of an opaque conductive material, such as a metal layer. In some cases, either the first electrode 3 or the second electrode 4 may take the form of an opaque electrode that is further from the pattern being measured, with the other electrode of the pair taking the form of an electrode that allows light to reach the photocapacitive material 2. Alternatively, the opaque electrode 24 may be very thin so that some light is transmitted to the photocapacitive material 2.

[0108] With particular reference to FIG. 2I, a porous electrode 26 is shown.

[0109] The porous electrode 26 takes the form of a porous conductive layer 27 that includes an area fraction of voids 28 that allow light to pass through the photocapacitive layer 2. The porous conductive layer 27 can be formed from a metal or any other conductive material that can be processed to form a porous conductive layer 27. Either or both of the first electrode 3 and the second electrode 4 may take the form of a porous electrode 26.

[0110] Optical Capacitive Sensor Referring also to FIG. 3, an optical capacitance sensor 29 is shown.

[0111] Optical capacitance sensor 29 includes an input surface 30, one or more light sources 31, and an array 36 of optical capacitors 32 (FIG. 4). Input surface 30 is provided by a transparent layer 33 formed, for example, from glass or a transparent plastic such as polyethylene terephthalate (PET) or polycarbonate (PC). Input surface 30 is the side of transparent layer 33 facing away from light source(s) 31, and transparent layer 33 has a second side 34 facing light source(s) 31. One or more light sources 31 are positioned to illuminate portion 35 (FIG. 14) of input surface 33 (i.e., through transparent layer 33) with emitted light 37.

[0112] 4, the optical capacitors 32 are arranged in an array 36, for example, a two-dimensional Cartesian array as shown in FIG. 4. The array 36 may include N rows and M columns of optical capacitors 32, where N and M are each integers equal to or greater than 2, and N and M may be equal or different. The capacitance of the nth optical capacitor 32 in the Nth row and the mth optical capacitor in the Mth column is denoted by C. nm Unless otherwise specified, references to the optical capacitor 32, C nm is the geometric contribution C dark Instead, the optical capacitance contribution C photo The geometric contribution C darkis assumed to be the same for all optical capacitors 32, although slight variations are taken into account during calibration of optical capacitance sensor 29. Array 36 of optical capacitors 32 is positioned to receive reflected light 38 corresponding to reflection of emitted light 37 from an object 39 in contact with or proximity to illuminated portion 35 (FIG. 14) of input surface 30. Array 36 of optical capacitors 32 is configured to detect the reflection pattern of object 39.

[0113] In FIG. 3 , the reflection pattern is shown as, for example, skin ridges corresponding to a fingerprint (including a thumbprint). This is an example of a reflection pattern formed by a relief (height) on the surface of the object 39. However, the reflection pattern for detection using the optical capacitance sensor 29 is not limited to reflection patterns generated by a relief on the surface of the object 39. In general, the optical capacitance sensor 29 can be employed to detect reflection patterns in the form of an albedo pattern, a color pattern, or any other pattern of the object 39 that can generate a pattern of spatially varying reflectance. In particular, the detection of human skin ridges is not limited to fingerprints (including thumbprints) but can also be applied to palmprints or any other part of the body that has a characteristic pattern of skin ridges and valleys.

[0114] The pitch (or spacing) of the optical capacitors 32 in the array 36 should be configured to provide sufficient spatial resolution to resolve the reflectance pattern of the object 39 to be measured. In the fingerprint measurement example shown in Figures 3 and 4, the row and column spacing of the optical capacitors 32 should be small enough to detect human skin ridges, such as those that form fingerprints. In general, however, the pitch or spacing between the optical capacitors 32 forming the array 36 can be tailored to the desired application and may be less than 1 mm, less than 0.5 mm, equal to the spacing of pixels on an associated display screen, etc.

[0115] Each photocapacitor 32 may include a photocapacitor material layer 2 as described above and have the structure of photocapacitor 1. Alternatively, as described further below, each photocapacitor 32 may have a structure similar to that of a thin film transistor (TFT) except that the source and drain electrodes are shorted (FIG. 19). The photocapacitor material layer 2 of each photocapacitor 32 may include or be formed from a disordered crystalline or polycrystalline material to contain trap states in the band gap of the material capable of absorbing subgap photon energy. The photocapacitor material layer 2 of each photocapacitor 32 may include or be formed from one or more of amorphous silicon, amorphous semiconductor oxide, organic material, etc.

[0116] The optical capacitance sensor 29 may be implemented as a passive sensor and / or part of a passive sensing layer (not shown). In the example shown in Figure 4, the optical capacitance sensor 1 is implemented as part of an active sensing layer 40.

[0117] The active sensing layer 40 includes a number M of transmission lines 41, each connected to a respective signal source 42. The active sensing layer 40 also includes a number N of reception lines 43, each connected to a respective detector circuit 44. Photo capacitor 32C nm connects the mth of the M transmit lines 41 to the nth of the N receive lines 43. In use, the array 36 excites the transmit lines 41 one at a time with a time-varying signal, causing the capacitance C of the connected optical capacitors 32 to mn is scanned, detecting from the receive lines 43 using each detector circuit 44. Detection may be based on the charge stored by each photocapacitor 32, the phase difference of the time-varying signal between the transmit line 41 and the receive line 43, or other techniques known in the art for measuring capacitance. For example, when the mth transmit line 41 is excited with a time-varying signal, the photocapacitor 32C m1 , C m2 ,···,C mN is measured, and then the next set of optical capacitors 32 is measured by exciting the m+1th transmission line.

[0118] In other examples, a single signal source 42 may be connected to each of the transmission lines 41 using a multiplexer (not shown), or fewer than M signal sources 42 may be connected to groups of transmission lines 41 using a corresponding number of multiplexers (not shown). In some examples, a single detector circuit 44 may be connected to each of the receive lines 43 using a multiplexer (not shown), or fewer than M detector circuits 44 may be connected to groups of receive lines 43 using a corresponding number of multiplexers (not shown).

[0119] In the example of an optical capacitance sensor 29 shown in Figure 3, an array 36 of optical capacitors 32 is positioned between one or more light sources 31 and the input face 30. As a result, in addition to reflected light 38, emitted light 37 may impinge on the optical capacitors 32. To mitigate this and reduce the monitored optical capacitance C mn Optical capacitance C photoの There are several possible approaches to effectively limiting the detection sensitivity to component changes.

[0120] The first approach is to calculate the optical capacitance from the emitted light 37 by dividing the geometric contribution C of each optical capacitor 32 by dark including the baseline capacitance C base For example, the optical capacitance contribution C photo is the contribution C from synchrotron radiation 37 emit and the contribution C from reflected light 38 reflect If the desired signal C is divided into Reflect can be obtained as follows:

number

number

[0121] This approach can be easily implemented in existing capacitance measurement systems, such as those used for capacitive touch, since they are typically only concerned with the change in capacitance and not its absolute value.

[0122] A second approach to eliminating the impact of the emitted light 37 on the optical condenser 32 is to use several directional light sources 31, positioned in the gaps between the optical condensers 32, to emit light 37 toward the input face 30. Such a staggered arrangement (i.e., an interpenetrating array of optical condensers 32 and light sources 31) can minimize the amount of emitted light 37 that impinges on the optical condenser 32 while still illuminating the input face 30.

[0123] Another approach to eliminating the effect of the emitted light 37 on the optical capacitor 32 is to use an optional patterned light-attenuating layer 45 disposed between the optical capacitor 32 and the light source(s) 31. The light-attenuating layer 45 is configured to shield the optical capacitor 32 from direct illumination by the emitted light 37 from one or more light sources 31, at least within the wavelength range to which the optical capacitor 32 is sensitive. For example, the light-attenuating layer 45 may include gaps 46 corresponding to the spaces between the optical capacitors 32 forming the array 36. The light-attenuating layer 45 may be opaque and may substantially or completely block the emitted light 37. Alternatively, the light-attenuating layer 45 may be selectively light-blocking and may take the form of a filter configured to block light within the wavelength range to which the optical capacitor 32 is sensitive. In a further alternative, if the emitted light 37 is polarized, the light-attenuating layer 45 may be a polarizer that blocks the polarized emitted light 37.

[0124] The light-attenuating layer 45 may be a layer separate from the optical capacitors 32, as shown in Figure 3. However, in some cases, the light-attenuating layer 45 may be integrated with each optical capacitor 32. For example, the bottom of the first electrode 3 and the second electrode 4 may be an opaque electrode 24 or an electrode patterned as a polarizer.

[0125] The optical condenser 32 does not need to be located between the light source(s) 31 and the input face 30 .

[0126] For example, and referring also to FIG. 5, a second optical capacitance sensor 47 is shown.

[0127] The second optical capacitance sensor 47 is the same as the optical capacitance sensor 29 (hereinafter referred to as the "first" optical capacitance sensor 29), except that the one or more light sources 31 are directional and emit light 37 towards the input face 30, and the one or more light sources 31 are positioned between the array 36 of optical condensers 32 and the input face 30 (vertically, i.e., along the z-axis as shown).

[0128] For example, one or more light sources 31 may include several light sources 31 positioned over gaps between light condensers 32 to form an interpenetrating array (or, for example, a single large area emitter with gaps corresponding to light condensers 32). In this way, light reflected from the pattern of object 39 can pass through gaps between light sources 31 and reach light condenser 32. Alternatively, if light source(s) 31 are transparent to reflected light 38, one or more light sources 31 can laterally overlap (or completely cover) the underlying light condenser 32.

[0129] In yet another example, the optical condenser 32 and the directional light source 31 may be substantially coplanar.

[0130] The optical capacitance sensor 29, 47 may be implemented as part of a button, touchpad, touchpanel, touchscreen, etc. An advantage of the optical capacitance sensor 29, 47 is that it may be operable even when the input surface 30 is wetted with and / or submerged in water or any other fluid, provided the fluid is transparent at the wavelengths emitted by the light source(s) 31 and sensed by the optical capacitor 32.

[0131] The light source(s) 31 are not particularly limited and may take the form of a single large area light emitter such as a light emitting diode (LED) or organic light emitting diode (OLED). Alternatively, the light source(s) 31 may form an array of a single type of light emitter (e.g., LED or OLED) or an array of sub-pixels, each sub-pixel containing two or more different types (e.g., colors) of light emitters. In some examples, the light source(s) 31 may be provided by one or more pixels or sub-pixels of a display device.

[0132] Some or all of the one or more light sources 31 may take the form of infrared (IR) emitters, such as IR LEDs or IR OLEDs. The infrared emitters may correspond to a peak emission in the range between (and including) 800 nm and 2,500 nm. Some or all of the one or more light sources 31 may take the form of emitters selected from red, green, and blue emitters, such as LEDs or OLEDs. A sub-pixel may include, for example, a red light source 31, a green light source 31, and a blue light source 31.

[0133] The optical capacitance sensor 29, 47 may optionally include one or more conductive traces (not shown) for projected capacitance measurements. Alternatively, the electrodes defining the optical capacitor 32 may be used to perform capacitive touch measurements either sequentially (time division multiplexed) or simultaneously with optical capacitance measurements.

[0134] Display screen integration Although the optical capacitance sensor 29, 47 can be used as a stand-alone sensor to measure the reflectance pattern of the object 39, the optical capacitance sensor 29, 47 can also be integrated into a wide range of different display types and at various locations within these display types. The cover lens of such an integrated display can provide the input surface 30.

[0135] For example, the photocapacitive sensor 29, 47 may be embedded in an active matrix liquid crystal display (AMLCD) and / or active matrix OLED (AMOLED) architecture. Due to the principle of capacitance change upon illumination, the photocapacitive sensor 29, 47 may be fully compatible for implementation in existing capacitive touch systems that also rely on capacitance change. The amorphous layer providing the photocapacitive layer 2 can be integrated into any existing capacitive touch panel as a passive dielectric layer, or in other examples, can be a separate layer in terms of a separate readout, but can maintain the same readout infrastructure.

[0136] Under-display architecture The photo-capacitance sensors 29, 47 may be located below the pixel layer of the display, and each photo-capacitor 32 may be configured as a simple passive capacitor that may have a standard readout provided to a standard touch controller (not shown) connected to the display, which may read out the array 36 of photo-capacitors 32 in discrete time periods to perform capacitive touch measurements.

[0137] For example, referring to FIG. 6, a first display under laminate 48 is shown.

[0138] A first display bottom laminate 48 is stacked in a direction between the substrate 49 and the input surface 30 and includes an array 36 of photo capacitors 32, a collimating layer 50, a TFT layer 51, an emissive layer 52 (which provides the light source(s) 31), a polarizing layer 53, an optional capacitive touch electrode layer 54, and a cover glass 55. The layers 36, 50, 51, 52, 53, 54 are supported on the substrate 49, and the stack is bonded to the cover glass 55 with a layer of optically clear adhesive (OCA) 56. The first display bottom laminate 48 generally corresponds to, for example, an LED or OLED type display panel and the like.

[0139] The collimating layer 50 is a light control film (LCF), also known as a light collimating film, and takes the form of an optical film configured to adjust the directionality of transmitted light. The collimating layer 50 may take the form of, for example, a microlens array, a pinhole array, or a light guide grid. The collimating layer 50 provides maximum transmittance at a predetermined angle of incidence relative to the image plane and provides image cutoff or blackout along a given polar coordinate, depending on the application requirements. The TFT layer 51 controls the illumination of the pixels forming the emissive layer 52. The emissive layer 52 is formed from pixels or sub-pixels of light emitters in the form of LEDs, OLEDs, or ultra-LEDs (uLEDs). The emissive layer 52 may take the form of a standard RGB pixel display, or each sub-pixel may include red, green, blue, and IR emitters.

[0140] Cover glass 55 may be any material suitable for use in a touch screen display, such as glass, a transparent polymer, or the like.

[0141] Referring also to FIG. 7, a second display bottom laminate 57 is shown.

[0142] The second 62 display bottom laminate 57 is stacked in a direction between the substrate 49 and the input surface 30 and includes an array 36 of photo capacitors 32, a backlight layer 58 (providing the light source(s) 31), an optical layer 59, a TFT layer, a liquid crystal (LC) layer 60, a color filter (CF) and black matrix (BM) layer 61, an optional capacitive touch electrode layer 54, an OCA and polarizer layer 62, and a cover glass 55. The second 62 display bottom laminate 57 generally corresponds to, for example, a backlit LCD panel or the like.

[0143] The TFT layer 51, in combination with the color filters of the CF and BM layers 61, controls the switching of the pixels defined by the LC layer 60. The backlight layer 58 provides the light source(s) 31 and emitted light 37.

[0144] The touch electrode layer 54 is optional and may be omitted in both the first display bottom laminate 48 and the second display bottom laminate 57. If present, the touch electrode layer 54 can be used to detect a user's touch.

[0145] On-display (or on-cell) architecture Referring also to FIG. 8, a first display-on (or "on-cell") stack 63 is shown.

[0146] The first on-cell laminate 63 is the same as the first under-display laminate 48, except that the array 36 of photocapacitors 32 is between a polarizer 53 (with optional capacitive touch electrodes 54 shown above) and an OCA layer 56, instead of between the substrate 49 and the TFT layer 51. Optionally, a light-attenuating layer 45 can be included anywhere between the array 36 and the light-emitting layer 52.

[0147] The first on-cell stack 63 is reminiscent of a standard on-cell capacitive touch architecture, and the array 36 can be integrated into the capacitive touch stack and read out using the same readout technology and touch controller (not shown) as capacitive touch. Preferably, the capacitive touch and photocapacitive signals are not mixed, but instead are time-multiplexed for readout. In this way, the photocapacitive measurement can be integrated using the same readout infrastructure as capacitive touch, simplifying the electronics. Alternatively, the photocapacitive measurement can have separate readout electronics to the capacitive touch function.

[0148] Referring also to Figure 9, a second display-on (or "on-cell") stack 65 is shown.

[0149] The second on-cell laminate 64 is the same as the second under-display laminate 57, except that the array 36 of light capacitors 32 is between the CF&BM layer 61 (with optional capacitive touch electrodes 54 shown above) and the OCA and polarizer layer 62, instead of between the substrate 49 and the backlight layer 58. Optionally, the substrate 49 may be configured as a reflector 65. Optionally, a light-attenuating layer 45 may be included anywhere between the array 36 and the backlight layer 58.

[0150] The second on-cell stack 64 has corresponding advantages to the first on-cell stack with respect to integration with capacitive touch.

[0151] In-display (or in-cell) architecture Referring also to FIG. 10, a first in-display (or in-cell) stack 66 is shown.

[0152] The first in-cell laminate 66 is the same as the first display-under laminate 48 or the first on-cell laminate 63, but instead of being a separate layer, the array 36 of photocapacitors 32 is integrated with the TFT layer 51. In this way, the photocapacitors 32 can use the same amorphous Si layer that defines the TFTs to provide the photocapacitive material layer 2, simplifying fabrication and reducing the number of layers. Further integration is also possible, as the TFT structure can be modified to provide the photocapacitors 32 by shorting the source and drain electrodes together (FIG. 19). In use, a corresponding photocapacitance C is generated between the shorted source and drain electrodes and the gate electrode. photo can be read.

[0153] Smartphones operating with low-temperature polysilicon (LTPS) transistors for the TFT layer 51 may already include a-Si:H for use as the photocapacitive material layer 2. In fact, LTPS is often formed from laser-crystallized a-Si:H. As a result, fabricating the array 36 and the TFT layer 51 from a single layer of material synergistically reduces the number and complexity of manufacturing displays incorporating photocapacitive sensors.

[0154] Readout of the capacitance from array 36 is the same as any of the touch panels described above, where the capacitance is read out by a touch controller (not shown) at a time separate from standard capacitive touch, for example through appropriate logic gating.

[0155] Referring also to Figure 10, a second intra-display (or in-cell) stack 67 is shown.

[0156] The second in-cell laminate 67 is the same as the second under-display laminate 57 or the second on-cell laminate 64, but instead of being a separate layer, the array 36 of photocapacitors 32 is integrated with the TFT layer 51. Optionally, a light-attenuating layer 45 can be included between the TFT and photocapacitive layers 36, 51 and the backlight layer 58.

[0157] The second in-cell stack 67 offers similar advantages as the first in-cell stack 66, but for LC display architectures.

[0158] On-display (or on-cell) architecture Referring also to FIG. 12, a third on-cell stack 68 is shown.

[0159] The third on-cell stack 68 is the same as the first on-cell stack 63, except that the array 36 has been moved between the light-emitting layer 52 and the polarizing layer 53, rather than between the polarizing layer 53 and the cover glass 55. Optionally, a light-attenuating layer 45 can be included anywhere between the array 36 and the light-emitting layer 52.

[0160] Referring also to FIG. 13, a fourth on-cell stack 69 is shown.

[0161] The fourth on-cell stack 69 is the same as the third on-cell stack 64, except that the array 36 has been moved between the LC layer 60 and the CF and BM layer 61, rather than between the CF and BM layer 61 and the cover glass 55. Optionally, a light-attenuating layer 45 can be included anywhere between the array 36 and the backlight layer 58.

[0162] For both the third on-cell stack 68 and the fourth on-cell stack 69, the capacitive touch electrode 54 is located on the light-emitting layer 52 and the LC layer 60, respectively. The photo-capacitive layer 2 of the array 36 of photo-capacitors 32 can be made of the same or equivalent material as the TFT layer 51, but its implementation can be in the form of a passive capacitor (see FIG. 1).

[0163] Although a variety of different display stacks have been described, the use of optical capacitance sensors 29, 47 in this specification is not limited to the explicitly described display stacks, and optical capacitance sensors 29, 47 can be added (or integrated, if compatible) between layers of any type of display architecture.

[0164] Irradiation range The illuminated portion 35 (FIG. 14) generally corresponds to the extent of the array 36 of light condensers 32. For example, in a display, a display pixel may illuminate substantially the entire cover glass 55 that provides the input surface 30. However, the illuminated portion 35 is considered to be the portion of the input surface 30 that overlies the array 36 of light condensers 32.

[0165] Referring also to FIG. 14, a first display layout 70 is shown.

[0166] The device 71 includes a display area 72. In a first display layout 70, the illuminated portions 35 corresponding to the optical capacitive sensors 29, 47 correspond to a first region 73 of the display area 72. In the example shown in FIG. 14, the first region 73 extends substantially along the edge of the display area 72. However, the shape, relative size, and relative position of the first region 73 within the display area 72 are not limited to the specific example of FIG. 14. For example, the first region 73 can be located in the center of the display area 72.

[0167] In this way, a device 71, such as a phone or tablet computer, may be provided with an optical capacitive sensor 29, 47 in an area 73 of the display that is sensitive to a user's fingerprint (including a thumbprint), such that fingerprint authentication can be used, for example, to unlock the phone and / or authorize transactions without sacrificing the display area 72 to a separate button or reader.

[0168] Referring also to FIG. 15, a second display layout 74 is shown.

[0169] The second display layout 74 is the same as the first display layout 70, and further includes an additional optical capacitive sensor 29, 47 having an illuminated portion 35 corresponding to a second region 75 of the display area 72 that is different from the first region 73. In the example shown in Figure 15, the first region 73 extends along a first edge of the display area 72, and the second region 75 extends along an opposite second edge of the display area 72. However, the shape, location, and relative sizes of the two distinct regions 73, 75 can all be defined depending on the intended application.

[0170] Referring also to FIG. 16, a third display layout 76 is shown.

[0171] The third display layout 76 is the same as the first display layout 70 , except that the first region 73 extends all the way around the display area 72 .

[0172] However, illuminated portion 35 is not limited to only regions 73, 75 of display area 72, and in some examples, illuminated portion 35 may be coextensive with display area 72. For example, referring also to FIG. 17 , a fourth display layout 77 is shown in which illuminated portion 35 is coextensive with display area 72.

[0173] Example of integrating an optical capacitor into the TFT layer 18 and 19, a specific example 78 of a second in-cell stack 67 is described to provide one exemplary method of integrating an array 36 of photocapacitors 32 within the TFT layer 51.

[0174] In the illustrated example, the backlight layer 58 includes a mixture of white LEDs 79 (or OLEDs) and IR LEDs 80 (or OLEDs). Stacked between the backlight layer 58 and the TFT layer 51 are a backlight diffusing layer 81, an optical film layer 82, a first polarizing layer 83, and a patterned conductive layer 84 that provides electrical connections to one side of the TFT layer 51.

[0175] The TFT layer 51 includes a blue pixel 85 corresponding to a blue filter 86 in the CF and BM layer 61, a green pixel 87 corresponding to a green filter 88 in the CF and BM layer 61, a red pixel 89 corresponding to a red filter 90 in the CF and BM layer 61, and a TFT integrated photo capacitor 91.

[0176] Referring specifically to FIG. 19, each TFT integrated photocapacitor 91 includes a dielectric layer 92 supporting a semiconductor region 93 having photocapacitive properties. A source electrode 94 is deposited on one side of the semiconductor region 93, and a drain electrode 95 is deposited on the opposite side, defining a channel between the source electrode 94 and the drain electrode 95. A gate 96 is deposited on the opposite side of the dielectric 92 from the semiconductor region 93. A first conductive trace 97 connects to the gate electrode 96, and a second conductive trace 98 connects to both the source electrode 94 and the drain electrode 95. As a result, the source electrode 94 and the drain electrode 95 are shorted together. The capacitance C photo is measured between the gate 96 and the associated source and drain electrodes 94 and 95 .

[0177] In this way, the TFT-integrated photocapacitor 91 can have the same structure as the pixel defining TFTs 85, 87, 89, with only the layout of the conductive traces connecting to the TFT layer 51 having to be modified. This allows the TFT-integrated photocapacitor 91 to be added almost seamlessly to the fabrication of conventional display TFT layers.

[0178] Each of the blue, green, and red pixels 85, 87, and 89 has the conventional configuration of pixels in a backlit LCD display.

[0179] The CF and BM layer 61 also includes a conventional black matrix (BM) material 99. Preferably, the BM material 99 is transparent to the IR wavelengths emitted by the IR LED / OLED 80, such that emitted light 37 can reach the input surface 30 and object 39, and reflected light 38 can reach the TFT integrated optical capacitor 91. Additionally or alternatively, the BM material 99 may include additional openings (not shown) to allow passage of emitted light 37 and reflected light 38, for example, between the input surface 30 and the TFT integrated optical capacitor 91.

[0180] Stacked between the CF and BM layer 61 and the cover glass 55 are, in that order, a second polarizing layer 100, an optically clear adhesive layer 101, and a third polarizing layer .

[0181] Device including an optical capacitance sensor Referring also to FIG. 20, a system 110 is shown.

[0182] The system includes a device 111 that includes optical capacitance sensors 29 , 47 and a controller 112 .

[0183] The controller 112 is connected to the optical capacitance sensors 29, 47 via a link 113, and the controller 112 measures the capacitance C of the array 36 of optical capacitors 32. mn The device is configured to measure

[0184] In relation to the above example, the controller 112 may be a touch controller, and the system 110 may also include a display underlying, overlying, or integrated with the optical capacitance sensors 29, 47. In other words, the system 110 and the device 111 may be part of a larger device such as a phone, tablet computer, etc.

[0185] Alternatively, the system 110 may form part of an access control system for devices other than phones or tablets, as described below.

[0186] The controller 112 includes one or more processors 114, a volatile memory 115, and non-volatile storage 116. The non-volatile storage 116 stores the capacitance C of the array 36 of photo-capacitors 32. mn The controller 112 stores program code 117 for controlling the controller to measure capacitance C and perform other functions described herein. The controller 112 also includes an output for controlling the signal source 42 or capacitance C mn The optical capacitance sensor 29, 47 may directly output a time-varying signal for directly measuring the capacitance of the optical capacitance sensor 29, 47. Similarly, the controller 112 may also include one or more detector circuits 44. In some examples, a device such as a phone, tablet computer, or the like incorporating the optical capacitance sensor 29, 47 may include some or all of the necessary data processing capacity, volatile and non-volatile storage.

[0187] Optionally, the controller 112 may calculate the measured capacitance C of the array of optical capacitors 36 when one or more light sources are illuminated without an object 39 above or in contact with the input surface. base The reference frame 118 corresponding to the capacitance C measured from the array 36 of optical capacitors 32 can be stored in the storage 116 to implement equation (3) above. mn The reference frame 118 can be configured to be subtracted from the

[0188] Optionally, the controller 112 may be further configured to control the emission of light from one or more light sources 31 of the optical capacitance sensors 29, 47. In such an example, to conserve power, the controller 112 may adjust the capacitance C of the array 36 of optical capacitors 32. mn The light source 31 can be illuminated only when it is desired to measure the fingerprint pattern of someone touching the input surface 30. For example, if the light source 31 takes the form of an IR emitter integrated into an RGB display, the IR emitter may not need to be illuminated all the time. If the display includes capacitive touch sensing functionality, the controller 112 can illuminate the IR emitter (light source 31) in response to capacitive touch detection to measure the fingerprint pattern of someone touching the input surface 30.

[0189] One possible advantage of optical capacitors for fingerprint (or other skin pattern) sensing compared to conventional capacitive fingerprint sensing is the possibility of checking that the detected fingerprint pattern corresponds to a live human. For example, conventional capacitive fingerprint sensing is based on electrical conductivity and can be spoofed using mocked-up fingerprint patterns.

[0190] An optical capacitance sensor 29, 47 integrated with a display having red, green, blue, and IR light emitting capabilities can be used to check for the presence of oxygenated hemoglobin in the contact object 39. For example, the controller 112 may illuminate only the red light source 31 (pixels / subpixels) and measure the first set of capacitances C from the array 36. mn and then illuminating only the IR light source 31 (pixels / subpixels) to measure a second set of capacitances from the array 36. mn By comparing the reflectances at red and IR wavelengths, the controller 112 can determine the ratio of reflectances at red and IR wavelengths, thereby distinguishing live human skin from spoofed fingerprint patterns. Note that since spatial resolution is only required for the pattern itself, the determination of the ratio of reflectances at red and IR wavelengths can be performed using aggregated measurements for improved accuracy.

[0191] The controller 112 selects capacitance C from the array 36 of photocapacitors 32. mn Upon measuring the pattern, the pattern may be compared to a set of one or more recognized patterns 119. Each recognized pattern 119 may correspond, for example, to the fingerprint of a person authorized to use a device or equipment associated with the system 110 or to enter an area associated with the system 110. The comparison performed by the controller 112 is performed by comparing the capacitance C mn The measured capacitance C measured using the array 36 should be insensitive to the relative rotation of the patterns (i.e., the controller 112 should have the ability to apply a rotational transformation to one or both patterns). The recognized pattern 119 may be stored in a secure storage device 120 that communicates with the controller 112 using a wired or wireless link 121. Alternatively, the recognized pattern(s) 119 may be stored internally in the storage 116 of the controller 112. mn If the pattern matches any of the recognized patterns 119, the controller 112 outputs a signal using a wired or wireless link 122 to the device 123 associated with the optical capacitance sensor 29, 47 indicating that an authorized user has been detected.

[0192] If system 110 is integrated as part of a phone, tablet computer, or other device such as a printer or item of medical equipment, the entire process may be internal to that device (i.e., equipment 123 may simply be the remainder of the device that includes system 110).

[0193] When implemented as a standalone device, device 111 can function as an access control device for equipment 123 such as, for example, printers, medical equipment, doors, elevator control panels, automobiles, motorcycles, bicycles, and construction equipment such as bulldozers, backhoes, and excavators, aircraft, military equipment, etc. Additionally or alternatively, device 111 can function as an access control device for doors or locks providing access to medication cabinets, hospital wards such as obstetrics and delivery units, hotel guest room doors, hotel back doors, or any other room or space to which access control is desired.

[0194] Modification Of course, many modifications can be made to the above-described embodiments. Such modifications can include equivalent and other features that are known in the design and use of optical capacitance sensors, biometric sensors, and / or fingerprint and / or other distinctive pattern scanners, and that can be used instead of or in addition to the features described herein. Features of one embodiment can be replaced or supplemented by features of another embodiment.

[0195] Possible applications of the optical capacitance sensors herein used for pattern detection may include, but are not limited to, simultaneous scanning of multiple fingers on a handprint for access to mobile phones, general purpose displays, HID devices, enabling secure in-app and surface security fingerprint recognition; other applications, including engineering applications such as proof of authorization at the point of delivery of a service; and further applications, including providing an audit trail.

[0196] Further uses include medical displays, computers, MRI or other diagnostic machines, or any other medical equipment (e.g., only authorized staff can access the controls of a medical device), in-application authorization (e.g., printing prescriptions), audit trails, etc.

[0197] The optical capacitance sensors 29, 47 can be configured to enable through-glove security, for example, by using wavelengths that can be read through thin surgical gloves or other types of PPE gloves.

[0198] The optical capacitance sensors 29, 47 can be used, for example, to replace card, code and / or key security in hospitals, laboratories, or any other facility requiring access control. The optical capacitance sensors 29, 47 can be integrated directly into, for example, door handles, door push plates, locks, etc.

[0199] Separate projected capacitive and photocapacitive readout The aforementioned stacks 48, 57, 63, 64, 66, 67, 68, 69 may include dedicated electrodes 54 for projected capacitance measurements. As mentioned above, one option for such a configuration is to include separate readout electronics for photocapacitive and capacitive touch functionality.

[0200] For example, referring also to FIG. 21, a schematic diagram of a separate readout configuration 124 is shown.

[0201] The separate readout arrangement 124 includes a capacitive touch controller 125 coupled to the projected-capacitive touch electrodes 126 and a photo-capacitance controller 127 coupled to the photo-capacitance sensors 27, 47. The photo-capacitance controller 127 is configured to measure the photo-capacitance of the array 36 of photo-capacitors 32, 91 that form the photo-capacitance sensors 29, 47. The capacitive touch controller 125 is configured for projected-capacitance touch sensing using the projected-capacitance touch electrodes 126 (e.g., in the form of appropriate conductive traces). The capacitive touch controller 125 provides drive signals 128 to the projected-capacitance touch electrodes 126 and determines a capacitance for detecting user interaction based on corresponding received signals 129. Similarly, the photo-capacitance controller 127 provides drive signals 130 to the photo-capacitance sensors 29, 47 and the corresponding received signals 131 can be used to determine the aforementioned reflection patterns.

[0202] The outputs and inputs of the capacitive touch controller 125 and / or the photocapacitive controller 127 may be multiplexed to allow scanning of a greater number of electrodes than the number of channels on the respective controllers 125, 127.

[0203] The drive signals 128, 130 for the projected-capacitive and optical-capacitive measurements may be different. For example, the time constant of the projected-capacitive touch electrodes 127 (or the intersections therebetween) may be different from the time constant of the optical capacitor 32. Additionally and advantageously, frequency multiplexing the drive signals 128, 130 for the projected-capacitive and optical-capacitive measurements reduces crosstalk between the two measurements.

[0204] The projected capacitive touch electrodes 126 may take the form of, for example, the capacitive touch electrode layer 54 described above. A separate readout arrangement 124 may be used in the system 110 / device 111, in which case the photo-capacitance controller 127 may take the form of the controller 112 described above. Similarly, the photo-capacitance controller 127 may be provided by any controller configured to measure the photo-capacitance of the photo-capacitance sensors 29, 47 described herein.

[0205] In some examples, the capacitive touch controller 125 and the optical capacitance controller 127 may be provided by separate channels of a single device. For example, a capacitive touch controller may include K channels, the first 1 to k of which are dedicated to projected-capacitive measurements (providing the capacitive touch controller 125), and the remaining k+1 to K channels are dedicated to optical capacitance measurements (providing the optical capacitance controller 127).

[0206] The capacitive touch controller 125 can be used for self-capacitance or mutual capacitance measurements.

[0207] Time-division multiplexed readout of projected capacitance and optical capacitance It is not necessary to use separate electronics (or at least dedicated channels) for projected capacitance and optical capacitance measurements. Another option for stacks 48, 57, 63, 64, 66, 67, 68, 69 that include dedicated electrodes 54 for projected capacitance measurements and separate layers 36 of individual optical capacitors 32, 91 is to use a single capacitive touch controller and time-multiplex the projected capacitance and optical capacitance measurements. In this way, optical capacitance measurements can be integrated using the same readout infrastructure as capacitive touch, simplifying the electronics.

[0208] For example, and referring also to Figures 22A and 22B, a time division multiplexed readout configuration 132 is shown schematically.

[0209] The time division multiplexed readout arrangement 132 includes a controller 133 connected to the projected-capacitive touch electrodes 126 and the optical capacitance sensors 29, 47 via a switch network 134. The controller 133 is configured to time division multiplex alternating between projected-capacitive touch sensing and measuring optical capacitance from the optical capacitance sensors by controlling the switch network 134.

[0210] 22B, during first periods, such as from t0 to t1, t2 to t3, and t4 to t5, the switch network connects the controller 133 to the projected-capacitive touch electrodes 126. Interspersed with the first periods are second periods, such as from t1 to t2, t3 to t4, and t5 to t6, during which the switch network connects the controller 133 to the optical capacitance sensors 29, 47 for optical capacitance measurements.

[0211] The projected capacitive touch electrodes 126 may take the form of, for example, the above-described capacitive touch electrode layer 54. The time-division multiplexed readout arrangement 132 may be used in the system 110 / device 111, in which case the controller 133 may take the form of the above-described controller 112.

[0212] The switch network 134 further provides multiplexing such that a controller 133 with K channels can scan more than K drive / sense lines during the first projected capacitance measurement period t0-t1, t2-t3, t4-t5 and / or scan more than K photo capacitors 32 during the second photo capacitance measurement period t1-t2, t3-t4, t5-t6.

[0213] Combined projected capacitive and optical capacitive readout As previously mentioned, capacitive touch measurements can also be made sequentially (time multiplexed) or simultaneously with optical capacitance measurements using the electrodes that define the optical capacitors 32, 91. In such instances, the separate projected capacitive electrodes 54, 126 can be omitted, simplifying the sensor / display stack.

[0214] For example, and referring also to FIG. 23, a combined readout configuration 135 is shown.

[0215] The combined readout configuration 135 includes a controller 136 and optical capacitance sensors 29, 47. In the combined readout configuration 135, the controller 136 measures the capacitance of each optical capacitor 32, 91 two or more times and adjusts the light source 31 to obtain at least a pair of measurements: a first measurement corresponding to illumination of the optical capacitor 32 and a second measurement corresponding to a "dark" state where the light source 31 is not illuminating the area below the interaction site.

[0216] The combined readout arrangement 135 may be used in the system 110 / device 111, in which case the controller 136 may take the form of the controller 112 described above.

[0217] Any of the aforementioned optical capacitor 32, 91 structures and the electrodes defining them may be used in the combined readout configuration 135, as they all include a geometric capacitance component that couples to a user's finger and / or conductive stylus, enabling projected capacitive touch sensing.

[0218] However, the combined readout configuration 135 can also be applied to other configurations.

[0219] For example, referring also to Figures 24-26, the structure and operation of an integrated touch and light capacitive sensor 137 (hereinafter "third light capacitive sensor") is shown.

[0220] The third photo-capacitive sensor 137 is based on the understanding that the photo-capacitive material layer 2, as previously described, can be incorporated as a passive dielectric layer in any existing capacitive touch panel.

[0221] The third optical capacitive sensor 137 includes several, e.g., N, first electrodes 1381, 1382, ..., 1383 extending in a first direction x and spaced apart in a second, different direction y. N The third optical capacitive sensor 137 also includes several, for example M, second electrodes 1391, 1392, ..., 1393 extending in a second direction y and spaced apart in a first direction x. N A layer 140 of photocapacitive material 2 is disposed between the first electrodes 138 and the second electrodes 139 such that each intersection of the first electrodes 138 and the second electrodes 139 provides a photocapacitor 141 of the array 36 of third photocapacitive sensors 137. For example, N first electrodes 138 n n-th and m-th electrodes 139 m The mth intersection point is the capacitance C n,m Optical capacitor 141 having n,m to provide.

[0222] With particular reference to FIG. 26, layer 140 comprises a plurality of photovoltaic capacitors 140. n,m When the photocapacitive material 2 forming the layer 140 is irradiated, the dielectric constant changes, causing the first electrode 138 n and second electrode 139 m The distribution of the electric field lines 142 between the capacitance C n,m The geometrically couples to nearby conductive objects (in the usual way for projected capacitive touch) and also registers illumination via the photocapacitive component of the response.

[0223] Any number of additional dielectric layers (not shown) may be interposed between layer 140 and first electrode 138 and / or any number of additional dielectric layers (not shown) may be interposed between layer 140 and second electrode 139.

[0224] The layer 140 of photocapacitive material 2 does not have to be disposed between the first electrode 138 and the second electrode 139 .

[0225] 27, in another configuration, the first electrode 138 and the second electrode 139 may instead be substantially coplanar / located on the same surface. Such configurations of coplanar (or substantially coplanar) electrodes are known in the art of capacitive touch, for example, using a localized patch of insulator where the electrodes 138, 139 cross, to measure the capacitance associated with the fringing electric field between the electrodes 138 and 139, rather than the (minimized) overlap area of ​​the electrodes. For example, diamond pattern electrodes for mutual capacitance touch sensing.

[0226] The first electrode 138 and second electrode 139 are disposed on or above a layer 140 of photo-capacitive material 2 such that each intersection of a first electrode and a second electrode provides an array of photo-capacitors. The underlying layer 140 of photo-capacitive material 2 still interacts and modifies the capacitance between the co-planar electrodes, as shown by the field lines 142 depicted in Figure 27.

[0227] Any number of additional dielectric layers (not shown) may be interposed between layer 140 and first electrodes 138, 139.

[0228] The third optical capacitance sensor 137 can be disposed on (or integrated as part of) a display 143, e.g., an LCD, OLED, or any other type of display. A cover 144, e.g., a cover glass 55, can be bonded or otherwise secured with the third optical capacitance sensor 137 to protect the electrodes 138, 139 and provide the input surface 30. For example, the cover 144 can be bonded using an optically clear adhesive 145 when the third optical capacitance sensor 137 is on (or forms part of) the display 143.

[0229] Neither the first electrode 138 nor the second electrode 139 is limited to being disposed on either side of the layer 140 of photocapacitive material 2, nor is it limited to being disposed on or in the same plane above the layer 140 of photocapacitive material 2. In general, the relative position of the layer 140 with respect to the first electrode 138 and the second electrode 139 is limited only by the need for the electric field lines connecting the first and second electrodes to pass through the photocapacitive material 2. For example, in a further variation of the third photovoltaic element, the first electrode 138 and the second electrode 139 may be separated by a non-photocapacitive dielectric layer (not shown), and one or a pair of the layers 140 of photocapacitive material 2 may be disposed above and / or below the first electrode 138 and the second electrode 139. In other words, the layers may be stacked in the following order: layer 140 of photocapacitive material 2, first electrode 138, a non-photocapacitive dielectric layer (not shown), second electrode 139, and optionally, second layer 140 of photocapacitive material 2.

[0230] In another variation, the first electrode 138 and the second electrode 139 may be substantially coplanar and supported on a substrate, and the layer 140 of photocapacitive material 2 is substantially coplanar with the first electrode 138 and the second electrode 139 and is patterned to fill the space between the electrodes 138 and 139.

[0231] 28-30B, a method for using the combined readout configuration 135 will now be described.

[0232] First, the controller 136 scans the third optical capacitive sensor 137 in a conventional projected-capacitive mode, e.g., at a first frequency (or a first set of frequencies). In the projected-capacitive mode, fewer than all of the N first electrodes 138 and / or all of the M second electrodes 139 may be scanned. This is because, for example, the pitch of the electrodes 138, 139 for fingerprint sensing is on the order of 50 microns, whereas conventional projected-capacitive touch may use a pitch on the order of 5 mm.

[0233] Thus, the controller 136 may measure the capacitance of at least a subset of the array 36 of optical capacitors 32, 91, 141. Alternatively, some first electrodes 138 may be grouped together and / or some second electrodes 139 may be grouped together for projected-capacitive sensing. In some examples, all of the electrodes 138, 139 may be used for projected-capacitive sensing.

[0234] When a user interaction is detected, such as a finger 146 being pressed against the input surface 30, the controller 136 uses the projected-capacitive data to determine an interaction area 147 (dashed line in FIG. 28).

[0235] Within a dark region 148 (dashed line) bounded by interaction area 147 (which may be the entire interaction area 147), controller 136 shuts down all light sources 31, including both light sources specifically used for light capacitance measurements and any underlying pixels of display 143. See particularly Figure 29, e.g., times t0-t1 and t2-t3.

[0236] In the absence of local illumination, the capacitance of each optical capacitor is measured for each optical capacitor 32, 47, 141 within a measurement area 149 of the dark area 148 (which may be the entire dark area 148). With particular reference to FIG. 30A, this is the geometric capacitance component C geo Provides measurements of.

[0237] The controller 136 activates at least a subset of the light sources 31 corresponding to the measurement area 149 (which may be equivalent to the dark area 148 and / or the interaction area 147). The controller 136 then determines the total capacitance C total With particular reference to FIG. 30B, the total capacitance C total are the respective unilluminated (or dark) capacitances C geo The change ΔC from ΔC = C total -C geo and this change ΔC corresponds to the optical capacitance signal. The change ΔC corresponds to a value C corresponding to complete transmission of light through the input face 30 (i.e., light passing through the layer 140 once). trans and another value C corresponding to perfect reflection from the input surface 30 or from an object on or just above the input surface. refl The important point is that the measured change ΔC can be used to measure the reflectance pattern of the object 39.

[0238] The subset of light sources 31 may include all of the light sources 31 in the measurement area 149, or may be limited to all light sources 31 of a particular color. For example, the display 143 may include red (R), green (G), and blue (B) pixels, and the projected capacitive component C geo may all be deactivated to measure the total capacity C totalTo measure ΔC, only the red (R) light source may be activated. In some examples, different colors of light source 31 provided by display 143, e.g., R, G, and B, may be sequentially illuminated to obtain color-specific light capacitance measurements, enabling color imaging of object 39, e.g., a user's finger 146. In some examples, display 143 may include an IR light source (not shown) in at least one region, and only the IR light source may be reactivated for purposes of determining the light capacitance component ΔC. Color imaging, particularly the addition of IR measurements, may enable detection of oxygen-containing human skin, for example, to prevent spoofing using an image of a person's fingerprint. To provide additional security against spoofing, measurements may be extended for a period sufficient to detect the user's pulse.

[0239] The process of deactivating and activating light sources 31 can be repeated any number of times to refine the light capacity component ΔC, for example, by averaging values ​​measured during different time periods (e.g., t1-t2 and t3-t4). With particular reference to FIG. 29, two cycles are shown, but any number of cycles can be used. If light sources 31 include more than one color and more than one is used for the measurements, these may be performed one after the other or separated by a period in which all light sources 31 are deactivated.

[0240] Addressing scheme for combined readout configuration The combined readout configuration 135 can be further understood with reference to some specific examples of addressing electrodes used for both projected-capacitive touch sensing and optical capacitance measurement.

[0241] Referring also to FIG. 31, a first addressing scheme 160 for the combined readout configuration 135 is shown.

[0242] The first addressing scheme 160 uses an example of the third optical capacitance sensor 137 and utilizes the first electrode 138 and the second electrode 139 for both projected-capacitive touch detection and optical capacitance measurement. The first addressing scheme 160 is a specific implementation of the combined readout configuration 135.

[0243] The first addressing scheme 160 includes a drive module 161 configured to output drive signals 128, 130 to the optical capacitance sensor 160. The drive module 161 forms part of the controller 136 and has a number of transmitter outputs 1621, ..., 1626 that is less than the number N of first electrodes 138 of the third optical capacitance sensor 137. For the following description, the first electrodes are labeled a1 through f5 in FIG. 31. Each transmitter output 162 is connected to a group of two or more first electrodes 138, a1, ..., f5, via a respective multiplexer 164. For example, the first transmitter output 1621 is connected to first electrodes f1, f2, f3, f4, and f5 by a multiplexer 1641. The multiplexers 1641, . . . , 1646 may be provided by (or form part of) a transmitter switch network 165 (eg, provided by or forming part of the controller 136).

[0244] The output from each multiplexer 164 is connected to a subset (e.g., a1, a2, a3, a4) of spatially grouped first electrodes within the third optical capacitive sensor 137. In other words, each transmitter output 162 can be multiplexed to the first electrodes 138, a1, ..., f5, that correspond to a particular stripe or strip of the third optical capacitive sensor 137. The stripes that correspond to different groups of first electrodes 138, a1, ..., f5, are indicated in FIG. 31 by horizontal dashed lines.

[0245] The output to which each transmitter output 162 is connected by the transmitter switch network 165 is governed by a first control signal 166 provided by a processor (not shown) of the controller 136. Generally, the controller 136 may include one or more digital electronic processors (not shown), random access memory (not shown), and non-volatile storage (not shown), in addition to certain elements such as the drive module 161. The drive module 161, the transmitter switch network 164, and further components of the controller 136 described below may be provided by hardware circuits, by software modules executed by one or more processors of the controller 136, or by a combination of hardware and software.

[0246] The spacing of the first electrodes 138, a1, ..., f5 should be fine enough to allow resolution of the reflection pattern one wishes to measure. For example, for fingerprint measurement, the pitch of the first electrodes 138, a1, ..., f5 may be on the order of 50 μm, and each transmitter channel 162 may be connected by a multiplexer 164 to an area of ​​80 distinct first electrodes 138, a1, ..., f5 (FIG. 31 shows only five divisions for clarity). In contrast, a typical projected capacitive touch sensing panel may use an electrode pitch of a few mm, e.g., 5 mm.

[0247] To reduce scan time, each transmitter output 1621,...,1626 may be driven simultaneously using frequency division multiplexing of the drive signals 128,130 to minimize crosstalk between groups of channels.

[0248] For projected-capacitive sensing, scanning all electrodes in each group (e.g., a1-a5, or e1-f35) may be too time-consuming and / or unnecessary. Instead, a subset of the first electrodes 138, a1, ..., f5, may be driven for projected-capacitive mode. For example, only one first electrode 138 per transmitter channel 162 may be used, such as a3, b3, c3, d3, e3, and f3.

[0249] Alternatively, two or more (or all) of the first electrodes 138 per group can be connected together (using the switch network 166) for collectively driving during projective-capacitive sensing. For example, first electrodes b1, b2, b3, b4, and b5 can be connected together and driven as a single electrode in projective-capacitive sensing mode.

[0250] In response to the projected-capacitive sensing mode detecting a user touch, the transmitter switch network 165 can be used to address and drive all of the first electrodes 138, a1, ..., f5, corresponding to the measurement area 149 for high-resolution optical capacitance measurements. For example, a user's finger can be detected at low resolution, followed by a high-resolution scan of the measurement area 149 to extract the user's fingerprint, which can be compared with stored data to determine whether the user should be allowed to unlock the phone or open a high-security application (or "app"), such as a banking app.

[0251] Additionally, in some examples, prior to the optical capacitive scan, a second projected capacitive scan can be performed localized to the coarsely detected touch location using a majority of a1, ..., f5 of the first electrodes 138 to obtain a precise estimate of the size and / or shape of the interaction area 147.

[0252] The second electrodes 139 have similar dimensions, e.g., the same pitch, as the first electrodes 138. For purposes of the following description, the second electrodes 139 of the third photocapacitive sensor 137 are labeled g1 through k5 in FIG.

[0253] On the receive side, a group of second electrodes 139, g1, ..., k5, is connected by a respective multiplexer 168 to a respective amplifier 172. For example, second electrodes g1, g2, g3, g4, and g5 are connected by multiplexer 1681 to a first amplifier 1721. The configuration is similar to the transmitter side, with each group of second electrodes 139 (e.g., h1-h5, j1-j5, etc.) corresponding to a strip or stripe of the third photocapacitive sensor 137, shown by vertical dotted lines in FIG. 31.

[0254] Multiplexers 1681,...,1685 are provided by or form part of receiver switch network 167, which is part of controller 136, just like driver module 161 and / or transmitter switch network 165. The connection paths through receiver switch network 167 are governed by second control signals 169 provided by a processor (not shown) of controller 136.

[0255] Similar to the addressing of the first electrodes 138, a1, ..., f5, for projected-capacitive sensing mode, it is not necessary to scan or monitor each of the second electrodes 139, g1, ..., k5. Instead, one second electrode 139 may be monitored per multiplexer 168, e.g., second electrodes 139, g3, h4, i3, j3, and k3 may be monitored for projected-capacitive touch sensing. Similarly, two or more second electrodes 139, g1, ..., k5, may be connected together and monitored as a single electrode.

[0256] The output of each amplifier 1711,...,1715 passes through a respective bandpass filter 1741,...,1745 and is converted to the digital domain by an analog-to-digital converter (ADC) 1751,...,1755. Each set of amplifier 171, filter 174, and ADC constitutes a receiver channel of front-end module 171. Front-end module 171, as well as drive module 161, transmitter switch network 165, and receiver switch network 167, are provided by or formed as part of controller 136. Receiver outputs 1701,...,1705 are passed to a processor (not shown) of controller 136 to determine the touch location in projected-capacitive mode and the reflection pattern of object 39 in optical-capacitive mode.

[0257] In this way, conventional touch sensing using an existing projected capacitive touch controller can be combined with photocapacitive measurements using the same touch controller with minimal changes to the control electronics. Furthermore, because the layer 140 of photocapacitive material 2 can replace any existing dielectric layer of a capacitive touch sensor / touch screen, minimal changes are required to the touch sensor stackup or structure.

[0258] While in fingerprint biometrics it is advantageous to scan only the measurement area 149 determined based on projected capacitance measurements, there are also applications where it is useful to scan all of the optical capacitances 141 in the array 36. For example, a phone or tablet computer configured with the combined readout arrangement 135 and first addressing scheme 160 can be used to scan documents into a file.

[0259] Similarly, a user may use a device equipped and configured as described herein to scan textures, materials, fabrics, etc. Information obtained using optical capacitive scanning may be transmitted to an online store to assist the user in identifying matching textures, materials, fabrics, etc. that the user may wish to purchase.

[0260] 31 shows a subdivision of the first electrodes 138 and second electrodes 139 into a fine pitch across the entire area of ​​the third projected-capacitive sensor 137, in other examples, a hybrid addressing scheme may be used. For example, only some of the transmitter outputs 162 may be multiplexed to the fine-resolution first electrodes 168 (and similarly to the second electrodes 169 and receiver channels), thereby allowing the area where the fine-resolution first electrodes 168 and second electrodes 169 intersect to be used for high-resolution optical capacitive measurements (e.g., measuring fingerprints for biometric authentication) while reducing the total number of electrodes and manufacturing complexity.

[0261] Although the first addressing scheme 160 is shown using the third optical capacitance sensor 137, the same or an equivalent addressing scheme may be applied to the first optical capacitance sensor 32 or the second optical capacitance sensor 47.

[0262] Referring also to FIG. 32, a second addressing scheme 180 is shown.

[0263] The second addressing scheme 180 is identical to the first addressing scheme 160 except for the routing between the transmitter channel 162 and the first electrodes 138, a1, ..., g5, and the routing between the second electrodes 139, g1, ..., k5 and the receiver channels 172, 174, 175.

[0264] In particular, instead of being connected to spatially grouped subsets of the first electrodes 138, a1, ..., f5, the outputs of the multiplexers 1641, ..., 1646 are interleaved within one or more spatially grouped subsets of the first electrodes 138, a1, ..., f5 such that each first electrode 138, a1, ..., f5 of that group can be connected to a different transmitter output 162 via a respective multiplexer 164. For example, the output of multiplexer 1642 in Figure 32 is connected to first electrodes b1, c2, d3, e4, and f5. Meanwhile, first electrodes e1, e2, e3, e4, and e5 corresponding to measurement area 149 can be simultaneously driven by respective transmitter outputs 1621, 1622, 1623, 1624, and 1625 via respective multiplexers 1641, 1642, 1643, 1644, 1645 (using frequency division multiplexed drive signal 130). Receiver switch network 167 is similarly configured.

[0265] This second addressing scheme 180 is more complex than the first addressing scheme 160, but its ability to simultaneously drive and / or monitor closely spaced electrodes 138, 139 may enable faster, higher resolution optical capacitive scanning, for example, to measure a user's fingerprint.

[0266] Hand / Palm Detection Although we have described a method for determining touch location using projected capacitance measurements followed by high-resolution optical capacitance scanning to capture, for example, a fingerprint, the systems and methods herein are not limited to a single instantaneous touch and / or fingerprint.

[0267] For example, and also referring to Figures 33A-33C, the entire hand / palm can be detected.

[0268] Referring specifically to FIG. 33a, a user's hand 182 (typically) has five fingers 1461, . . . , 1465.

[0269] With particular reference to FIG. 33B, when the entire hand is pressed against the input surface 30, the corresponding interaction area 147 corresponds to the outline of the hand.

[0270] The device 111 may be further configured to analyze the shape and / or size of one or more interaction regions 147 to determine suitable measurement regions 147 (and optionally dark regions 148) by combining projected capacitive and optical capacitive capabilities, for example, using separate readout configurations 124, time-multiplexed readout configurations 132, or combined readout configurations 135.

[0271] 33C , device 111 may determine whether a user interaction, i.e., a detected interaction area 147, corresponds to all or a portion of a user's hand 182 in contact with input surface 30, and in response to determining that the detected interaction area 147 corresponds to all or a portion of the user's hand, may determine one or more measurement areas 149 in the form of fingerprint areas corresponding to the ends of fingers 1461, ..., 1465. In the example shown in FIG. 33C , device 111 identifies the end of each finger and thumb and assigns a corresponding measurement area 1491, ..., 1495. The optical capacitance corresponding to each measurement (fingerprint) area 1491, ..., 1495 may then be measured.

[0272] Other measurement areas 149 may also be defined, for example, the pattern of skin ridges on the palm of the user's hand may be added to the fingerprint data for added security.

[0273] Different sizes and / or shapes of measurement areas 149 can be defined for optical volumetric imaging using different color light sources 31. For example, referring also to FIG. 33D , measurement areas 1831, ..., 1835 may be defined for IR imaging (preferably near-IR, NIR) of subsurface veins. Measurement areas 1831, ..., 1835 for vein imaging may extend further along each finger 1461, ..., 1465 than the respective measurement areas 1491, ..., 1495 for fingerprints. Vein imaging can help prevent spoofing because the pattern of veins beneath a user's skin is also distinctive and difficult to spoof (e.g., forgery using a clone). To reduce scanning time and power consumption, the scan resolution for vein imaging can be lower than that for fingerprint scanning.

[0274] For authentication purposes, it is necessary to ensure that a sufficiently large area is measured to avoid matching similar areas within larger, different patterns.

[0275] Referring also to Figure 34A, a first contact area 1841 between a user's finger 146 and the input surface 30 is shown, with the resolution of the projected capacitive scan visually indicated by the dashed lines forming a grid. A corresponding first interaction area 1471 is shown in Figure 34B.

[0276] Referring also to FIG. 35A, a second contact area 1842 between the user's finger 146 and the input surface 30 is shown, and a corresponding second interaction area 1472 is shown in FIG. 35B.

[0277] Referring also to FIG. 36A, a third contact area 1843 between the user's finger 146 and the input surface 30 is shown, and a corresponding third interaction area 1473 is shown in FIG. 36B.

[0278] Different sizes of the contact area 184 relate to different pressures with which the user presses the finger 146 against the input surface 30. Generally, the harder the finger 146 presses, the larger the contact area 184 will be, and the more of the corresponding fingerprint / thumbprint will be in contact with or close enough to the input surface 30 for optical capacitive scanning.

[0279] Since the device 111 only measures the interaction areas 1471, 1472, 1473, it is necessary to analyze the area (and any shape) of the interaction areas 1471, 1472, 1473. The comparison of the pattern of light capacitance against a set of one or more recognized patterns 119 can be performed provided that the interaction areas 147 (more specifically, the corresponding measurement areas, if different) exceed a minimum area. For example, it may be determined that the first interaction area 1471 and the second interaction area 1472 are large enough (e.g., exceed a threshold) to capture a significant proportion of the fingerprint / thumbprint, but the third interaction area 1473 may be too small.

[0280] The size of the interaction area 147 can be determined based on projected capacitance measurements alone or using a combination of projected capacitance and optical capacitance measurements.

[0281] If the device 111 includes a display and it is determined that the interaction area 147 is insufficient for the comparison, the display can be controlled to display a message instructing the user to reposition the finger (or palm, etc.) and / or press harder to allow for a more complete measurement.

[0282] Transmission-based optical capacitance sensing Examples have been described in which optical capacitors 32, 47, 141 are configured to detect light from a light source 31 that is reflected from an object 39 that is in contact with or close to (eg, <1 mm) the input surface.

[0283] However, the array 36 of photocapacitors 32, 47, 141 and the associated readout and addressing schemes described above may also be applied in other applications.

[0284] For example, and referring also to FIG. 37, a presentation system 190 is shown.

[0285] The presentation system 190 includes a fourth optical capacitance sensor 191, which includes an input surface 30 and an array 36 of optical condensers 32, 47, 141 positioned to receive light 192 from a light source 193 transmitted through the input surface 30. The light source 193 is a highly collimated light source with a small divergence angle 194, such as a laser pointer. The spacing between elements of the array 36 of optical condensers 32, 47, 141 should be configured to detect a laser point spot, for example, between approximately 1 mm and 5 mm. The presentation system 190 also includes a controller 195 configured to monitor the optical capacitance of the fourth optical capacitance sensor 191.

[0286] The input surface 30 here may correspond to a large display screen, a smart screen onto which a projector is pointed, and similar systems that display content on a large scale to an audience. The addition of a fourth optical capacitance sensor 191 allows the presenter to interact with the displayed content using a laser pointer, providing a cursor that functions similarly to a mouse or trackball.

[0287] Although the claims have been set forth in this application to particular combinations of features, it is to be understood that the scope of the present disclosure also includes any novel feature or any novel combination of features or any generalization thereof disclosed herein, either explicitly or implicitly, whether or not they relate to the same invention as presently claimed in any claim, and whether or not they alleviate any or all of the same technical problems that the present invention alleviates. Applicant hereby gives notice that new claims may be devised to such features and / or combinations of such features during the prosecution of this application, or of any additional applications derived therefrom.

Claims

1. An input surface; one or more light sources arranged to illuminate an illuminated portion of the input surface; an array of optical capacitors positioned to receive light from the one or more light sources reflected from an object in contact with or in proximity to the illuminated portion of the input surface; Including, the array of optical capacitors is an optical capacitance sensor configured to detect a reflection pattern of the object; a controller connected to the optical capacitance sensor and configured to measure the capacitance of the array of optical capacitors; An apparatus comprising: The controller measuring the capacitance of at least a subset of the array of optical capacitors; identifying an interaction region based on the capacitance of the subset of the array of optical capacitors; deactivating each light source corresponding to the interaction area; measuring a projected capacitance component of each optical capacitor corresponding to the interaction area; activating at least a subset of the light sources corresponding to the interaction area; measuring the total capacitance of each optical capacitor corresponding to the interaction area; identifying an optical capacitance component corresponding to the interaction region based on a difference between the total capacitance and each of the projected capacitance components; configured to include Device.

2. The device of claim 1 , wherein the array of optical capacitors is configured to detect fingerprints.

3. the one or more light sources are directional and emit light towards the input face; 3. The apparatus of claim 1 or claim 2, wherein the one or more light sources are disposed between the array of light condensers and the input surface.

4. The array of optical capacitors is disposed between the one or more light sources and the input surface, and the optical capacitance sensor comprises: a light-attenuating layer disposed between the one or more light sources and the array of light capacitors and configured to shield the light capacitors from direct illumination by the one or more light sources within a wavelength range to which the light capacitors are sensitive. further comprising:

3. The device according to claim 1 or claim 2.

5. The apparatus of any one of claims 1 to 4, wherein the one or more light sources include one or more infrared emitters.

6. 6. The apparatus of claim 1, wherein the one or more light sources include one or more emitters selected from red, green, and blue emitters.

7. the array of optical capacitors a plurality of first electrodes extending in a first direction and spaced apart in a second direction, wherein the second direction is different from the first direction; a plurality of second electrodes extending in the second direction and spaced apart in the first direction; a layer of photocapacitive material disposed between the first electrode and the second electrode such that each intersection of the first electrode and the second electrode provides a photocapacitor of the array; and The apparatus according to any one of claims 1 to 6, comprising:

8. the array of optical capacitors a plurality of first electrodes extending in a first direction and spaced apart in a second direction, wherein the second direction is different from the first direction; a plurality of second electrodes extending in the second direction and spaced apart in the first direction; Including, the plurality of first electrodes and the plurality of second electrodes are substantially coplanar and disposed on or above a layer of photocapacitive material such that each intersection of the first electrode and the second electrode provides a photocapacitor of the array; The device according to any one of claims 1 to 6.

9. An apparatus as described in any one of claims 1 to 8, wherein the optical capacitance sensor comprises a display screen having a cover lens and a display laminate, the display laminate including the optical capacitance sensor, and the cover lens providing the input surface.

10. the display laminate includes a backlight layer; the backlight layer provides the one or more light sources or the backlight layer includes the one or more light sources; 10. The apparatus of claim 9.

11. the display stack includes a pixel layer in the form of an array of light emitting diodes; the array of light emitting diodes provides the one or more light sources or the array of light emitting diodes includes the one or more light sources; 10. The apparatus of claim 9.

12. the display laminate includes a thin film transistor layer; the thin film transistor layer provides or includes the array of photocapacitors; An apparatus according to any one of claims 9 to 11.

13. A device according to any one of claims 9 to 11, wherein the display laminate comprises a thin film transistor layer and a separate photocapacitor layer.

14. the display laminate has a display area; The device of any one of claims 9 to 13, wherein the illuminated portion of the input surface corresponds to a first region of the display area.

15. The optical capacitive sensor according to claim 1, further comprising a second optical capacitive sensor identical to the optical capacitive sensor; The device of claim 14 , wherein the second optical capacitive sensor is associated with a portion of the input surface that corresponds to a second area different from the first area of ​​the display area.

16. The device of any one of claims 9 to 13, wherein the display laminate has a display area, and the illuminated portion of the input surface substantially corresponds to the display area.

17. The device of any one of claims 9 to 16, wherein the display laminate includes conductive traces for projected capacitive touch sensing.

18. An apparatus described in any one of claims 1 to 8, comprising an access control device including the optical capacitance sensor.

19. An apparatus as described in any one of claims 9 to 17, comprising an access control device including the display screen.

20. in response to detecting a user interaction using projected capacitance measurements; determining whether the user interaction corresponds to all or part of a user's hand touching the input surface; determining one or more fingerprint regions in response to determining that the user interaction corresponds to all or a portion of a user's hand; Responsive to determining one or more fingerprint regions, measuring a light capacitance corresponding to each fingerprint region. The device according to any one of claims 1 to 19, configured so as to

21. the controller stores a reference frame corresponding to the measured capacitance of the array of optical capacitors when the one or more light sources are illuminated without the object above or in contact with the input surface; the controller is further configured to subtract the reference frame from the capacitance measured from the array of optical capacitors. An apparatus according to any one of claims 1 to 20.

22. the controller is further configured to control light emission from the one or more light sources; or a second controller configured to control light emission from the one or more light sources; 22. Apparatus according to any one of claims 1 to 21.

23. 23. The device of any preceding claim, wherein the controller is further configured to measure a capacitance of the array of optical capacitors in response to detecting a touch using projected capacitance.

24. In response to detecting a touch using projected capacitance, the controller causes the one or more light sources to illuminate; The apparatus of any preceding claim, wherein the controller is further configured to measure the capacitance of the array of optical capacitors.

25. In response to detecting a touch using projected capacitance, the second controller causes the one or more light sources to illuminate; 23. The apparatus of claim 22, wherein the controller is further configured to measure a capacitance of the array of optical capacitors.

26. the one or more light sources include one or more infrared light sources and one or more red light sources, and the controller: illuminating the infrared light source and measuring a first set of capacitances from the array of optical capacitors; Illuminating the red light source and measuring a second set of capacitances from the array of optical capacitors. It is configured as follows: the controller is configured to compare the first set of capacitances with the second set of capacitances to determine whether an object above or in contact with the input surface corresponds to human skin.

25. Apparatus according to any one of claims 1 to 24.

27. 27. The device of claim 26, wherein the controller is further configured to control the one or more infrared light sources and the optical capacitance sensor to detect and / or image one or more veins in the object.

28. The one or more light sources include one or more infrared light sources and one or more red light sources, and the second controller: illuminating the infrared light source and measuring a first set of capacitances from the array of optical capacitors; Illuminating the red light source and measuring a second set of capacitances from the array of optical capacitors. It is configured as follows: the controller is configured to compare the first set of capacitances with the second set of capacitances to determine whether an object above or in contact with the input surface corresponds to human skin.

23. The apparatus of claim 22.

29. The device, comparing the pattern of capacitance measured using the array to a set of one or more recognized patterns; outputting a signal in response to the pattern of capacitance measured using the array matching a recognized pattern of the one or more recognized patterns. An apparatus according to any one of claims 1 to 28, configured to:

30. 30. The apparatus of claim 29, wherein the comparison of the pattern of capacitance to the set of one or more recognized patterns is conditioned on the measured pattern of capacitance corresponding to an interaction region that exceeds a minimum area.

31. 31. A method of measuring the capacitance of an array of optical capacitors using an apparatus according to any one of claims 1 to 30.

32. reading or acquiring a reference frame corresponding to the measured capacitance of the array of optical capacitors when the one or more light sources are illuminated without the object above or in contact with the input surface; subtracting the reference frame from the capacitance measured using the array of optical capacitors; 32. The method of claim 31 , further comprising:

33. comparing the pattern of capacitance measured using the array to a set of one or more recognized patterns; outputting a signal in response to the pattern of capacitance measured using the array matching a recognized pattern of the one or more recognized patterns; 32. The method of claim 31 , further comprising:

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