WO2015107516A1 - Capteur de proximité transparent - Google Patents

Capteur de proximité transparent Download PDF

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Publication number
WO2015107516A1
WO2015107516A1 PCT/IL2015/050036 IL2015050036W WO2015107516A1 WO 2015107516 A1 WO2015107516 A1 WO 2015107516A1 IL 2015050036 W IL2015050036 W IL 2015050036W WO 2015107516 A1 WO2015107516 A1 WO 2015107516A1
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WO
WIPO (PCT)
Prior art keywords
wires
pads
capacitance
sensing surface
wire
Prior art date
Application number
PCT/IL2015/050036
Other languages
English (en)
Inventor
Ori Rimon
Rafi Zachut
Original Assignee
Zrro Technologies (2009) Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zrro Technologies (2009) Ltd. filed Critical Zrro Technologies (2009) Ltd.
Publication of WO2015107516A1 publication Critical patent/WO2015107516A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
    • G06F3/0443—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using a single layer of sensing electrodes
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/04164—Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
    • G06F3/04186—Touch location disambiguation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2203/00—Indexing scheme relating to G06F3/00 - G06F3/048
    • G06F2203/041—Indexing scheme relating to G06F3/041 - G06F3/045
    • G06F2203/04104—Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2203/00—Indexing scheme relating to G06F3/00 - G06F3/048
    • G06F2203/041—Indexing scheme relating to G06F3/041 - G06F3/045
    • G06F2203/04108—Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction

Definitions

  • the present invention is in the field of sensing techniques, and more particularly relates to capacitive proximity sensors for sensing a position of an object and generating data relating to the position of the object.
  • Touch screens are commonly used in electronic devices such as computers, laptops, desktops, tablets, televisions, and cellular phones, to enable a user to control the devices by moving the user's finger or a stylus near or on the touch screen.
  • a touch screen may be superposed with a transparent capacitive sensor matrix which senses the user's finger or stylus and generates data relating to the position of the object. This data is analyzed by a monitoring module and is fed to the electronic device, where a cursor could be created for tracking the object's motion, and certain gestures by the user are converted to instructions (for example, for manipulating an object).
  • Capacitive sensors are usually divided into mutual- capacitance sensors and self- capacitance sensors.
  • Mutual capacitance is capacitance that occurs between two charge-holding objects or conductors, in which the current passing through one object/conductor passes over into the other. The current between the two objects decreases when a third object is brought toward the first two objects.
  • a mutual-capacitive sensor uses this fact to sense when and where a user's finger or conductive stylus touches the sensor.
  • a mutual- capacitive sensor known in the art generally includes a grid formed by two perpendicular groups of strips (lines) of conductive material. Each group is composed by a respective number of parallel lines. A capacitor is present at each intersection between lines. A voltage is applied in a sequential fashion to the vertical lines of the grid, and an output voltage is measured on the horizontal (measurement) lines.
  • Bringing a finger or conductive stylus near the surface of the sensor changes the local electric field which reduces the mutual capacitance effect.
  • the capacitance change at every individual intersection on the grid can be measured to accurately determine the touch location by measuring the voltage in the rows of the grid.
  • Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be accurately tracked at the same time.
  • Self-capacitance requires only one electrode which holds a "floating capacitance".
  • the floating capacitance is influenced by parasitic capacitance between the electrode and surrounding electric conductors. Since the human body is a conductor, when a finger is placed close to the electrode, the value of the floating capacitance increases and can thereby be detected through a measurement terminal.
  • Self-capacitance sensors can have the same X-Y grid as mutual capacitance sensors, but the columns and rows operate independently. With self-capacitance, a voltage drop is indicative of the capacitive load of a finger on each column or row located near the finger. This produces a stronger signal than mutual capacitance sensing, but the X-Y grid self-capacitance sensor is unable to resolve accurately more than one finger or conductive stylus at a given time.
  • the present invention is aimed at providing a novel type of capacitive sensor which is configured such that its sensing surface structure can be made of a substantially transparent material, and enables multi-touch and hover operation in three- dimensions, i.e. provides sensing signals which allow for multiple objects (e.g., finger or conductive stylus) position calculation even while at least some of (or all) the objects hover above the sensor and optionally some of the other objects touch it.
  • sensing surface structure can be made of a substantially transparent material
  • the capacitive sensor can overlaid on top of an active display device, like a LCD screen, to sense finger position (X/Y position) and height (Z) over the display.
  • an active display device like a LCD screen
  • the transparency of the material should be referred to the fact that, an underlying surface can be viewed through the sensor (sensing surface structure), and the behavior of the object (e.g. 3D location) can be viewed on the screen.
  • the electrical circuitry outside the sensor surface receiving the measurement data from the sensing pads can be located solely outside the active area of the sensing surface and not at the bottom or at the top of the active area (active area is the region of the sensing surface over which objects should be detected), and would therefore not hide the screen nor influence the measurements.
  • a conventional mutual capacitance sensor is generally incapable of sensing with desirably high resolution the location of a hovering object. This is because the measured voltage drop in response to a hovering object could be one -hundredth of the voltage drop measured in response to a touching object which is already weak comparing to the voltage drop sensed in the self- capacitance method. Moreover, the influence of a touching finger on the measurement line it touches could be greater than a hovering finger on a different position on the same line. Also, mutual capacitance is more sensitive to noise, as the noise injected by the finger might create phantom fingers all over the measurement line.
  • a mutual-capacitance sensor while it may provide multi-touch operation, is not suitable to operate as a three-dimensional sensor.
  • self- capacitance sensor having an X-Y grid it is possible to identify a hovering finger, due to the stronger signal strength.
  • the self-capacitance sensor is unable to resolve accurately the position of more than one object at a given time.
  • the present invention takes advantage of self-capacitance sensor having a two dimensional array of pads, as described in WO 2010/084498 and US 2011/0279397, which can operate as both a multi-touch sensor and as a three-dimensional sensor.
  • the present invention provides a novel configuration of such type of sensor, in which the sensor is made of transparent material.
  • the transparency of the sensor requires that, the electric circuit which excites the matrix pads and collects the measurements from the pads, is located outside the active area of the sensor. Thus, wires from the edges to the pads should be placed inside the active area of the sensor, where objects are to be detected.
  • hovering fingers' locations cannot be analyzed while those wires are exposed to other objects being detected, since the proximity of objects to them will distort the capacitance measurements associated with their respective pads. This distortion may be not critical when analyzing positions of touching fingers, but is critical when analyzing relatively weak signals corresponding to hovering fingers.
  • the capacitive sensing surface structure can be made of transparent material, while maintaining the capability to operate as both a multi-touch and three- dimensional sensor.
  • the present invention therefore provides a sensing surface structure associated with a self-capacitance sensor which is made of transparent material and solves the problem associated with the exposed pads' wires, by providing a sensing surface comprising inter alia one or more reference wires which can be used to deduct the electrical effect of the one or more objects on the pads' wires.
  • Embodiments of the invention disclose a sensing surface comprising reference wires configured to subtract the undesirable self-capacitance effect of the fingers on the wires. This approach suits the industry trend of using one layer solution.
  • the sensing surface has an active region (aka active area) in which the sensing pads are located and over which fingers are to be detected, and an edge region outside the active region (e.g. at the periphery of the sensing region).
  • active region aka active area
  • edge region outside the active region (e.g. at the periphery of the sensing region).
  • the pads' wires as well as the reference wires can be placed in either one of the active and edge regions, or in both of them.
  • each pad's wire is associated with one or more reference wires, and the reference wire(s) is/are placed beside the respective pad's wire.
  • the undesirable self-capacitance effect on the pad's wire is substantially the same as on the reference wire, and therefore can be subtracted from the measurement of the pad by means of appropriate hardware and/or software utility.
  • a group of pad wires is associated with one or more reference wires.
  • the undesirable self-capacitance effect on each of the pad wires of the group is substantially a factor of the self-capacitance effect on the respective reference wire(s), and therefore can be subtracted from the measurement of the pad by means of hardware and/or software utility.
  • At least some of the pad's wires are formed with a transparent conductive material.
  • the reference wires follow the pads' wires only in the edge region, i.e. outside the active area of the sensor over which fingers are to be detected.
  • a sensing surface configured for monitoring a three-dimensional behavior of one or more object over the sensing surface and providing measured data indicative thereof, the sensing surface comprising:
  • an active area comprising a plurality of sensing pads arranged on an insulating sheet in a spaced-apart relationship such that each of the sensing pads is electrically isolated from other pads, and an edge region located outside the active area and allowing for connecting the sensing pads to an electrical circuitry;
  • a plurality of wires comprising a pattern of pads' wires providing electrical connection of each of said sensing pads to the electrical circuitry, and a pattern of one or more reference wires configured and arranged with respect to the pads' wires to enable subtraction, from measurements sensed by the sensing pads, of undesirable electrical effect of the one or more objects on the pads' wires.
  • the sensing surface is substantially transparent at least within the active area thereof. At least some of the pad's wires may be at least partially made of a transparent conductive material.
  • the pads, the pads' wires and the reference wires may all be printed on the same insulating sheet.
  • the pattern of the pads' wires may be such that at least some of the pads' wires are at least partially located in the edge region.
  • at least one of the reference wires is at least partially located in the edge region.
  • the patterns of the pads' and reference wires are configured such that each of the pads' wires is associated with respective one or more reference wires placed beside the pad wire.
  • the patterns of the pads' wires and reference wires are configured such that a group of the pads wires is associated with respective one or more reference wires.
  • At least two adjacent sensing pads form a batch of the sensing pads covering a certain zone of the active area.
  • Such batch comprises an extension part configured for leaving space for another batch, and the one or more reference wire follows the extension part.
  • the pads layer may comprises one or more internal batches, each configured for using two reference wires; one reference wire being configured to enable subtraction of undesirable self-capacitance effect of the one or more objects on the extension part, and the other reference wire being configured to enable subtraction of undesirable self-capacitance effect of the one or more objects inside the batch area.
  • the sensing surface may include an electrical circuit connected at the edge region.
  • the electrical circuit is configured for receiving data from the pads and wires and generating corresponding measured data.
  • the electric circuitry may also be configured for processing the measured data and determining three-dimensional positions for multiple objects.
  • the electrical circuit may include at least one differential amplifier configured for subtracting the undesirable object-wire self-capacitance effect.
  • the differential amplifier may include two inputs and an output, where the first input is connected to the pad's wire, the second input is connected to the one or more associated reference wires such that the differential amplifier output represents the subtraction of the second input from the first input.
  • the electrical circuit may also include a compensation capacitor configured to equalize parasitic capacitance at the two inputs of the differential amplifier.
  • a proximity sensor device comprising the above-described sensing surface and a measurement unit connected to the edge region and comprising an electric circuitry configured to receive separately signals indicative of a self capacitance of the sensing pad and its respective pad's wire and a self-capacitance of the associated one or more reference wires.
  • the device may include a controller unit for subtracting the undesirable self-capacitance effect.
  • the controller unit may be configured for identifying wires affected by the undesirable self-capacitance effect of the one or more objects and for subtracting the undesirable self-capacitance effect for the affected wires.
  • the controller unit may be configured for determining a position of the one or more objects; and determining affected wires according to the position of the one or more objects.
  • the measurement unit may comprise at least one current source being connected to at least one of the respective pad's wires and the associated one or more reference wires, and being configured for injecting current for a certain injection period to at least one of the respective pad's wire and the reference wire.
  • the controller unit may be configured for receiving signals indicative of a self-capacitance of the pad and its respective wire and a self-capacitance associated with the one or more reference wires and for subtracting the reference wire self-capacitance from the measurement of the pad self-capacitance.
  • Fig. 1 illustrates a sensing surface with exposed pads' wires
  • Figs. 2a-2c illustrates a part of a sensing surface including a reference wire for each exposed pad wire according to some embodiments of the present invention
  • Figs. 3a-3g illustrate a part of a sensing surface including one reference wire for a group of pads' wires according to some embodiments of the present invention
  • Fig. 4 is a schematic drawing illustrating a lateral cross section of a sensing surface according to some embodiments of the present invention.
  • Fig. 5a is a schematic drawing exemplifying a pad matrix sensor in which the reference wires are located on the edges outside the active area of the sensing surface according to some embodiments of the invention
  • Fig. 5b is a schematic drawing illustrating a part of a matrix sensor in which part of the exposed pads' wires are within the active area of the sensing surface and another part of the pads' wires are on the frame (edge region) of the sensor outside the active area, and reference wires are located on the frame outside the active area, where the capacitance effect of objects outside the active area can be subtracted using the reference wires; and
  • Fig. 5c is a schematic drawing illustrating a part of a matrix sensor in which part of the exposed pads' wires are within the active area and another part of the pads' wires are on the frame of the sensor outside the active area, and reference wires are located on the frame outside the active area, where the undesirable self-capacitance effect of fingers on the active area on the exposed pads' wires can be subtracted without using reference wires.
  • Fig. 1 illustrates a sensing surface 200 of a matrix sensor which is exposed to object(s) whose behavior (including also three-dimensional behavior) is to be monitored (located).
  • the sensing surface 200 has an active area 251 in which a matrix of sensing pads is located (some of the pads being specifically referred to by numbers 203a-203d in this figure).
  • the sensing surface 200 also includes an edge region 250, which is located aside the active area. It should be understood that the edge region of the sensing surface may interface a part of the active area, or may at least partially surround the active area.
  • the sensing surface may have a substantially planar portion in which the active area is located (i.e. the pads are arranged) and a planar or not periphery portion in which the edge region is located.
  • the sensing surface includes the sensing pads associated with their exposed pads' wires, generally at 202.
  • These wires are thin (e.g. 100 micrometer), and accordingly the influence of touching such a wire by an object is negligible comparing to touching the sensing pad.
  • the wire width is 100 micrometer and the substrate used between the finger and the sensing surface (i.e. pads and wires) is a glass sheet having a thickness of 0.5 mm and a relative permittivity of 5
  • the influence of a touching finger on the wire 202 is around 150 fF
  • the influence of a touching finger on a pad of 100 mm area is around 10 pF.
  • C ⁇ ,- ⁇ /d
  • A the area of overlap of the two plates in square meters
  • ⁇ ⁇ the relative permittivity of the material between the plates
  • 3 ⁇ 4 the electric constant
  • d the distance between the plates in meters.
  • this type of matrix sensor can be used for touch sensing by setting a proper threshold for object detection. Also, if all the objects are to be detected at the same hover height (e.g. when the user wants to touch while wearing gloves made from fabric of thickness 1 mm), this matrix sensor can be used by setting a proper threshold for detection. This is because the influence of the object (through the glove) on the wires and pads reduces in the same ratio, and it is still easy to set a threshold for touch (through gloves) detection.
  • the capacitance associated with pads 203a, 203b, 203c, 203d could be 300 fF, 300 fF, 150 fF, 150 fF respectively, instead of 150fF, 150fF, 150fF, 150fF, which will shift the position calculation of finger 204 to the right. Since the capacitances which are to be detected for hovering sensing are below the undesirable object-wire self-capacitance, setting a threshold cannot eliminate the undesirable capacitance. For example, the influence of a touching finger on pad's wire can reach 150 fF, where in order to detect a finger at hovering height of 30 mm the sensing surface should be sensitive to capacitance of less than 50fF.
  • the novel transparent capacitive sensing surface of the present invention allows for providing reliable measured data from which three-dimensional positions for multiple objects can be accurately extracted.
  • Fig. 2a-2c partially illustrate a sensing surface 200 and exemplify the sensing surface operation for providing measured data indicative of a three-dimensional behavior of one or more objects thereover.
  • three- dimensional behavior may comprise at least one of the following: a three dimensional position of the one or more objects with respect to the sensing surface; a change in position of the one or more objects with respect to the sensing surface; a motion pattern of the one or more objects with respect to the sensing surface.
  • the sensing surface 200 comprises edge region 250, at the periphery of the sensing surface, through which the sensing surface can be connected to an electrical circuitry.
  • the sensing surface includes a pads layer, which within said edge region, comprising an insulating sheet (shown in Fig. 4), and a plurality of sensing pads (e.g. 203) overlaying the insulating sheet.
  • the sensing surface includes one or more reference wires, generally at 201. As described above, and will be specifically exemplified further below, at least some of the wires (pads' wires and/or reference wires) may be located in either one or both of the active and edge regions of the sensing surface.
  • the reference wires may serve for enabling subtraction of the signal associated with the undesirable capacitance of the one or more objects on the pads wires.
  • the size of the finger 204 e.g. finger with diameter 12 mm
  • the width of reference wire 201 and the pad's wire 202 e.g. the wires width is 100 micrometer
  • both wires are fairly close to each other (e.g. 20 micrometer separation)
  • the overlapping area of the finger with the reference wire 201 and with the pad's wire 202 is substantially similar (for example 1.2 mm 2 ).
  • the self-capacitance of finger 204 and reference wire 201 is substantially similar to the self-capacitance of the finger 204 and pad wire 202. Therefore, the self-capacitance of finger 204 and reference wire 201 is measured and then subtracted from the capacitance measurement associated with the respective pad 203 (that includes the self-capacitance of the finger-wire 202). The resulted measurement substantially describes the self-capacitance effect associated solely with pad 203.
  • a measurement unit 206 which is connected to the sensor (via its edge region).
  • Measurement unit 206 is configured for measuring voltages indicative of capacitance values and for converting them to digital values.
  • the digital values may be transferred via link 217 to a controller unit (CU) 207 e.g. MCU (microcontroller unit).
  • the CU 207 converts the digital value to capacitance values. Since the object-wire undesirable self -capacitance is similar to the object-reference wire self-capacitance, the CU subtracts the value of the object-reference wire self-capacitance from the value of the self-capacitance of a pad and its wire in order to get the value of the object-pad self- capacitance, which is the capacitance to be detected relating to the object's behavior.
  • the measurement unit 206 may include an electric circuit that directly outputs the value of the object-pad self-capacitance.
  • Fig. 2b exemplifies part of the sensing surface 200 of Fig. 2a and measurement unit 206.
  • the pad wire 202 is connected to a direct current source 361.
  • the input 373 of an analog to digital converter 371 is connected between current source 361 and pad wire 202.
  • the reference wire 201 is connected to a direct current source 362.
  • the input 374 of an analog to digital converter 372 is connected between current source 362 and reference wire 201.
  • the direct current source 361 injects for example a current I of 1 microampere for a period T of 1 microsecond through a combined capacitance CT of Cwl and Cp (the capacitors are in parallel connection).
  • the voltage at input 373 of analog to digital converter 371 can be calculated according to the following formula:
  • the analog to digital converter 371 outputs a digital value which corresponds to voltage:
  • the CU (not shown) may receive the digital values via link 217 and convert the digital values from the measurement unit 206 to capacitance values according to:
  • the CU may continue to perform the subtraction of the reference wire self- capacitance Cw2 from the combined self-capacitance of the pad Cp and its wire Cwl.
  • the values of the current I and the injection period T are determined according to several parameters such as: the voltage range (i.e. dynamic range) supported by measurement unit 206, the required resolution of the digital values from the analog to digital converters and the parasitic capacitance with the underlying surface (e.g. display) which was not considered for the sake of simplicity of the explanation. It should be noted that the capacitors discharge circuit and control signals were not considered also for the sake of simplicity.
  • the subtraction of the self-capacitance of finger and reference wire from the capacitance measurement associated with a pad can be approximated by an electric circuit.
  • the subtraction is done by providing an electrical circuit to be connected at the sensor edges.
  • the excitation and other self-capacitance circuit are not shown in Fig. 2c; only the relevant part of the receiving analog circuitry is shown.
  • the electrical circuit includes at least one differential amplifier configured for subtracting the undesirable object-wire self-capacitance effect (represented by voltage) from a pad's measurement as described above.
  • the capacitance measurement implementation may be not linear and additional hardware can be added in order to subtract the undesirable object- wire capacitance.
  • the parasitic capacitance between the pad 203 and an underlying conductor may cause that the electrical effect of the object- wire self-capacitance and the object-reference wire self capacitance will not be equal.
  • This can be solved by adding compensation capacitor 209 that equalizes the parasitic capacitance seen by the two inputs of the differential amplifier.
  • Fig. 3a illustrates a part of a sensing surface having one reference wire 201 for a group of close pads wires 210, 211, 212, 213. Since not all the pads wires have the same length as the reference wire, the case may be such that the object touches the reference wire but does not touch all the pads wires. In such a case, the subtraction of the self- capacitance of the reference wire from all the pads measurements may result in unnecessary subtraction (over subtraction).
  • object 204 touches the reference wire 201 and pad wires 210 and 211, but does not touch the pad wires 212, 213. Therefore the object 204 influences the reference wire 201 and pad wires 210 and 211 but does not influence pad wires 212, 213. If the measured self- capacitance of object-reference wire 201 is subtracted from the measurements of the self-capacitance associated with pads 203f, 203g, an over subtraction can be done.
  • Fig. 3b describing a specific but not limiting example of a subtraction method.
  • One way to avoid an over subtraction is to apply another subtraction method on a small batch of pads (e.g. 4 pads) which may include up to two objects in the batch area.
  • Two observations are used: (i) Due to the width of the wires, only touching (or near touching) objects may influence hovering performance, (ii) Any influence on wires of the pads which are touched by an object is negligible as compared to the influence on the pads. Therefore the position of a touching object can be accurately calculated. From observation (ii), if two objects touch the batch's pads then no subtraction is required. From observation (i), if no object touches the batch then no subtraction is required.
  • the affected wires can be detected, for example, according to the Y coordinate of the touching object which can be accurately calculated according to observation (ii). For example, it can be seen from the example of Fig. 3a that the wires 213 and 212 of pads 203g and 203f respectively, whose center is below the Y coordinate of the touching object 204 (whose position is 220), are not affected. Therefore the subtraction of the self-capacitance of the reference wire is done only for pads with center above the Y coordinate of the touching object.
  • the self-capacitance of the reference wire is similar to the self- capacitance of each of the affected pad wires. This is because the width of the group of pads' wires is relatively small (e.g. 1.5mm) comparing to the object size (e.g. finger with 1 cm area).
  • the number of touching objects in the batch area is calculated.
  • the number of local maxima which are above a certain threshold, and are in the vicinity of the batch area (e.g. the local maxima is one of the batch's pad or an adjacent pad), can be counted.
  • step 315 which is performed in a case when there are no touching objects or when there are two touching objects, the measurement is taken without subtraction of the self -capacitance of the reference wire.
  • Step 308 and 310 are performed if a single touching object was detected.
  • the position of the single detected touching object is calculated.
  • the position may be defined as the center of mass of the capacitance of the pads around and including the local maxima (which was founded in step 305).
  • the self-capacitance of the reference wire is subtracted only from those pads' measurements whose wires are affected.
  • Fig. 3c exemplifies on the left side a batch of pads, the pads' wires of which have an extension part 263 (i.e. the pads wires are extended downwards below the lower pad 203g), and on the right side the figure exemplifies an equivalent symbol 260 that will be used in Fig. 3d below.
  • the rectangle 261 symbolizes the batch's pads
  • the black rectangle 262 symbolizes the extension part 263 of the respective pads' wires.
  • the extension part is configured for leaving a space for another batch (not shown here) at the bottom. Therefore, batches of pads having an extension part are referred to as internal batches.
  • a batch which is located adjacent to the edge region of the sensing surface does not have an extension part.
  • Fig. 3d exemplifies the use of several batches in order to support large screen size (e.g. 10.1 inch).
  • large screen size e.g. 10.1 inch.
  • the pads wires 202A of batch A are extended downwards beside batch B and batch C.
  • each batch contains a plurality of pads, and that in this specific example each pad is connected to the edge via a respective wire; therefore a batch includes a plurality of wires.
  • the influence of touching objects on the extension part has to be considered as well (for example touching object 205).
  • the reference wire 201B follows the entire extension part of wires 202A of batch A. Therefore the self-capacitance of reference wire 201B should be subtracted from the measurements of all the pads of batch A and from the measurement of reference wire 201A in order to compensate for touch in the extension part. Then, in order to further compensate for touch inside the batch A's area/zone (for example touching object 204), the method of Fig. 3b may be used with respect to reference wire 201A.
  • each internal batch i.e. batch in which pads' wires have extensions towards the edge region of the sensing surface
  • the short reference wire configured for compensating for possible touch at the extension part is wire 201B
  • the long reference wire configured for compensating for possible touch inside the batch area is wire 201A.
  • the short reference wire configured for compensating for possible touch at the extension part is wire 201C
  • the long reference wire configured for compensating for possible touch inside the batch area is wire 201B.
  • the above-described method of Fig. 3b may be used, in order to compensate for their affected pad wires.
  • reference wire 201C may be used to compensate for touch on wires 202C.
  • the long reference wire of one batch can serve as the short reference wire for the adjacent batch above it.
  • reference wire 201B is the long reference wire of batch B and the short reference wire of batch A. Therefore, this configuration utilizes one reference wire per batch of pads.
  • the configuration exemplified in Fig. 3d may be also mirrored vertically and horizontally.
  • Fig. 3e exemplifying a subtraction method for an internal batch of pads based on the configuration of the sensing surface of Fig. 3d.
  • the self capacitance of the short reference wire which follows only the extension part of the batch, is subtracted from the batch's pads and from the long reference wire which follows the extension part and continues in parallel to the batch till the batch's end. This compensates for possible touch at the extension part.
  • step 335 the method of Fig. 3b is applied on the subtracted values from step 325 to compensate for touch inside the batch area.
  • Fig. 3f exemplifies another possible configuration of the sensing surface, according to some embodiments of the present invention.
  • the batches of pads are paired: one batch is associated with a spaced-apart parallel batch of pads.
  • the figure shows two such batch pairs: paired batches A and C and paired batches B and D.
  • the pads' wires are paired: every two wires from the paired batches face each other and therefore the respective batches can share their reference wires.
  • batch A and batch C use reference wires 201A and 201B as described above. This enables reducing the number of reference wires by factor of 2.
  • This configuration can be extended and duplicated as the dashed arrows 320 imply.
  • the configuration exemplified in Fig. 3f may be mirrored vertically.
  • Fig. 3g Another way to avoid over-subtraction is exemplified in Fig. 3g.
  • the pads' wires 210, 211 and 212 are extended beyond their respective pads 203g, 203f and 203e.
  • a bridge 220 made of a conductor overlaid on an isolation substrate may be used to connect a pad to its respective wire.
  • the object's 204 size and shape dictate that its overlapping area with reference wire 201 is substantially similar to its overlapping area with each of pads wires 210, 211, 212 and 213.
  • object 204 may be a finger with diameter of 10 mm and the width of the group of pads wires is about 1.5 mm width. Therefore, since generally the capacitance is in linear proportion to the overlapping area between two conductors, the object-reference wire self-capacitance is substantially the same as each of the object- pad's wire self-capacitance. Thus, the subtraction of the object-wire self-capacitance from the pad measurement can be done for all the pads.
  • the sensing surface 200 of Fig. 2a comprises an edge region 250 at the periphery of the sensing surface through which the sensing surface can be connected to electrical circuitry (not shown here), and a pads layer comprising a plurality of sensing pads (e.g. pad 203) made of a transparent material and overlaying an insulating sheet 401.
  • the pads are arranged on the insulating sheet 401 in a pattern configured such that each pad is substantially isolated from one another and there is an electrical connection between each of the sensing pads of the pattern and the edge region 250 (shown in Fig.
  • each wire 202 there is a respective associated reference wire 201 configured to enable subtraction of the object-wire self capacitance from the correspondent pad measurement, as explained above in reference to Figs. 2a-2c
  • a bottom shielding layer 500 is provided being located under insulator sheet 401 and under the sensing pads 203 and respective wires 202 and being isolated from the pads and wires.
  • the bottom shielding layer includes an insulating sheet 501 and conductor material 502 and can be attached to protect the pads, the pads' wires and the reference wires from noise and other electrical effects which can be radiated or conducted from elements under the sensor (e.g. display).
  • a non-limiting example of a transparent conductive material suitable for forming the pads and/or the pads' wires and/or the reference wires and/or the bottom shielding layer may be a transparent conductive oxide (TCOs), such as indium- tin oxide (ITO), fluorine doped tin oxide (FTO), and doped zinc oxide.
  • TCOs transparent conductive oxide
  • ITO indium- tin oxide
  • FTO fluorine doped tin oxide
  • a suitable transparent conductive material may be an organic film.
  • the organic film may be formed by carbon nanotubes and/or graphene, or may include a polymer, such as poly (3, 4-ethylenedioxythiophene) or a derivative thereof.
  • Insulating sheet 401 and 501 may be made of polyester PET film or glass, for example. In some embodiments, all of the components of the sensing surface are made of a transparent material.
  • the reference wires are shown as being located within the active area of the sensing surface. As indicated above, generally, the wires may be located in either one of active and edge regions or both of them.
  • Figs. 5a to 5c exemplifying the embodiments of the invention in which the reference wires are located outside the active area, i.e. are located within the edge region.
  • Fig.5a exemplifies a matrix sensor, where the plurality of pads are divided (i.e. with respect to arrangement of their associated wires) into batches of pads 261.
  • the wires are arranged such that parts of the pads' wires are located in the active area 251 of the sensing surface, and the extension parts 262 of the pads' wires and reference wires 201 are located on frame (edge region) 250 outside the active area.
  • the configuration may be such that at least the parts of the pads' wires which are located inside the active area 251 are made of a transparent material composition having relatively high resistivity (e.g.
  • the material composition of the extension parts of the pads' wires as well as that of the reference wires on the frame may be opaque material having relatively low resistance (e.g. ⁇ lOohm/square).
  • This embodiment allows to minimize the total resistance of each pad's wire when all pad's wires are terminated at a predefined location (e.g. a connector or a chip or a flex cable at the bottom edge). Locating the reference lines outside the active area provides for subtracting the capacitive effect of any object located on the frame (edge region) of the sensor. Similar to the described in Fig.4, when no bottom shielding layer is used, the sensing surface of this embodiment can be implemented as a single layer solution (where the pads, pads' wires and their extensions and the reference wires are all printed on the same insulating sheet).
  • Fig.5b it schematically illustrates a part of a matrix sensor (similar to that described above with reference to Fig.5a) in which the transparent conductive material used for the exposed pads' wires has relatively high resistivity.
  • Dashed line 602 schematically distinguishes between the active area 251 on its right side (which must be transparent) and the frame/edge region 250 on the left side.
  • the portions of the pads' wires in the active area are designated 202, and the extensions thereof within the frame are designated 202a.
  • the pads' wires portion 202 located in the active area 251 are made of the transparent conductive material with relatively high resistivity, and pads' wires portions 202a located on the frame/edge 250 (outside the active area) are made of opaque material having relatively low resistivity such as silver.
  • the pads' wires portions 202 and 202a are electrically connected.
  • Reference wires 201a and 201b which are terminated just outside the active area are used here to subtract the capacitance effect of any amorphic object 204 on the frame, such as the part of user's palm holding the sensor by its frame/edge.
  • a reference wire which follows (is parallel to / aligned with) closely e.g.
  • an extension part of the wires of a batch of pads can be subtracted from the batch's pads measurement in a straight forward fashion (i.e. without calculating the position of the object 204) because it senses a similar effect to that sensed by the extension part. This is similar to the subtraction of the short reference line described above with reference to Fig.3d.
  • Fig.5c there is schematically illustrated a matrix sensor generally similar to that presented in Fig.5b, namely having reference wires located only outside the active area.
  • Fingers i.e. objects to be detected and located
  • Fingers 204a, 204b i.e. their projections onto the sensing surface
  • the effect on the exposed pads' wires can be calculated and subtracted based on the position of the finger, size of the finger and the above predefined sets of parameter without the need of physical reference lines.
  • the subtraction of the influence of finger 204c which projection on the sensing surface is located outside the active area is done in a straight forward fashion using reference lines 201.
  • a thin finger e.g. a finger having a diameter of
  • the present invention provides a novel configuration of the sensing surface for use in a proximity capacitive sensor matrix, allowing the sensing surface to be transparent at least within the active area thereof where the sensing pads are located.
  • the proximity capacitive sensor device utilizing the invention enables multi-touch and hover operational modes in three-dimensions. This allows for detecting and locating multiple objects (e.g., finger or conductive stylus) when some or all the objects hover above the sensing surface, and also when one or more of the objects touch the active area of the sensing surface.
  • objects e.g., finger or conductive stylus
  • it can be implemented as a true single layer solution. This offers a cost reduction comparing to the present X-Y grid touch sensors which require two layers or one layer and conductive bridges.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Position Input By Displaying (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

L'invention concerne une surface de détection qui est configurée pour être utilisée dans un dispositif de capteur de proximité pour surveiller un comportement tridimensionnel d'un ou plusieurs objets sur la surface de détection. La surface de détection comprend : une zone active comprenant une pluralité de plots de détection agencés sur une feuille d'isolation dans une relation espacée de telle sorte que chacun des plots de détection est électriquement isolé d'autres plots; une région de bord située en dehors de la zone active et permettant la connexion des plots de détection à une circuiterie électrique; et une pluralité de fils comprenant un motif de fils de plots permettant une connexion électrique de chacun desdits plots de détection à la circuiterie électrique, et un motif d'un ou plusieurs fils de référence configurés et agencés par rapport aux fils des plots pour permettre une soustraction, à partir des mesures détectées par les plots de détection, d'un effet électrique indésirable du ou des objets sur les fils des plots.
PCT/IL2015/050036 2014-01-15 2015-01-11 Capteur de proximité transparent WO2015107516A1 (fr)

Applications Claiming Priority (4)

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US201461927509P 2014-01-15 2014-01-15
US61/927,509 2014-01-15
US201462000715P 2014-05-20 2014-05-20
US62/000,715 2014-05-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10747384B1 (en) 2019-08-01 2020-08-18 Stmicroelectronics Asia Pacific Pte Ltd Single layer capacitive touch matrix

Citations (3)

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Publication number Priority date Publication date Assignee Title
EP2363788A2 (fr) * 2010-03-02 2011-09-07 Hitachi Displays, Ltd. Dispositif d'entrée de coordonnées et dispositif d'affichage l'incluant
US20120081331A1 (en) * 2010-09-30 2012-04-05 Samsung Electro-Mechanics Co., Ltd. Touch screen
WO2013145785A1 (fr) * 2012-03-30 2013-10-03 Sharp Kabushiki Kaisha Dispositif à panneau tactile à capacité mutuelle et procédé de réalisation d'un dispositif à panneau tactile à capacité mutuelle

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
EP2363788A2 (fr) * 2010-03-02 2011-09-07 Hitachi Displays, Ltd. Dispositif d'entrée de coordonnées et dispositif d'affichage l'incluant
US20120081331A1 (en) * 2010-09-30 2012-04-05 Samsung Electro-Mechanics Co., Ltd. Touch screen
WO2013145785A1 (fr) * 2012-03-30 2013-10-03 Sharp Kabushiki Kaisha Dispositif à panneau tactile à capacité mutuelle et procédé de réalisation d'un dispositif à panneau tactile à capacité mutuelle

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10747384B1 (en) 2019-08-01 2020-08-18 Stmicroelectronics Asia Pacific Pte Ltd Single layer capacitive touch matrix
CN112306310A (zh) * 2019-08-01 2021-02-02 意法半导体亚太私人有限公司 单层电容触摸矩阵
EP3771973A1 (fr) * 2019-08-01 2021-02-03 STMicroelectronics Asia Pacific Pte Ltd. Matrice tactile capacitive monocouche

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