Capacitive sensing device

Abstract

A capacitive sensing device is provided, comprising: a plurality of driving electrodes to which a first voltage is applied, wherein the plurality of driving electrodes are arranged side by side along a first direction; a plurality of sensing electrodes to which a second voltage having a sign opposite to that of the first voltage is applied, wherein one of the plurality of shaped electrodes is located between two adjacent driving electrodes; and a processing circuit for detecting changes in capacitance between the driving electrodes and the sensing electrodes.

Description

Technical Field

[0001] The present disclosure relates to a capacitive sensing device, a device having the capacitive sensing device, and a method for generating an image such as a fingerprint image using the device. The device may be a mobile phone, a smart phone, a tablet computer, a personal computer, a digital camera, a navigation system, etc. Background Art

[0002] In recent years, authentication technologies implemented in various electronic devices, such as mobile phones, smartphones, tablets, personal computers, digital cameras, and navigation systems, have become increasingly important to prevent unauthorized use. Fingerprint sensors (FPSs) are a promising candidate for use in these devices due to their size and energy efficiency. While there are many types of FPS sensors, capacitive FPSs have attracted significant attention due to their thin profile, low cost, and high reliability.

[0003] Capacitive FPS can be implemented in devices where the display panel covers almost the entire front surface. In this case, the sensor should be arranged under a cover layer such as transparent glass or film of the display panel. If the thickness of the cover layer is 200μm or less, the existing capacitive FPS can detect surface irregularities of a finger placed on the cover layer with sufficient resolution to identify the fingerprint. However, a cover layer with a thickness of 200μm or less is easily broken even by a slight impact. Therefore, in order to implement a capacitive FPS in a full-screen display device, it is necessary to increase the sensitivity of the capacitive FPS to accurately detect fingerprints through thick cover layers. Summary of the Invention

[0004] The embodiments provide a capacitive sensing device, a device having the device, and a method for generating an image such as a fingerprint image. The device may be a mobile phone, a smart phone, a tablet computer, a personal computer, a digital camera, a navigation system, etc.

[0005] A first aspect of the embodiment provides a capacitive sensing device. In a first possible implementation of the first aspect, a capacitive sensing device includes: a plurality of drive electrodes to which a first voltage is applied, wherein the plurality of drive electrodes are arranged side by side along a first direction; a plurality of sensing electrodes to which a second voltage having a sign opposite to that of the first voltage is applied, wherein one of the plurality of shaping electrodes is located between two adjacent drive electrodes; and a processing circuit for detecting a change in capacitance between the drive electrodes and the sensing electrodes. In some examples, the electrode spacing can be in a range of 30 μm to 150 μm, and the device can preferably be used to generate a fingerprint image. In addition, the first voltage and the second voltage can be applied to the drive electrode and the shaping electrode, respectively, during a predetermined drive period to synchronously drive the drive electrode and the shaping electrode. On the other hand, reading a signal from the sensing electrode is performed during a predetermined reading period that is different from the drive period.

[0006] When a first voltage is applied to the drive electrode, an electric field is generated between the drive electrode and the sensing electrode, and the sensing electrode receives charge from the drive electrode. In addition, when a finger is located on the cover layer above the device, the finger causes the electric field to change and reduces the mutual capacitance between the drive electrode and the sensing electrode. The resolution of detecting surface irregularities of a finger may be related to the directionality of the electric field between adjacent drive electrodes and sensing electrodes. Specifically, increasing the directionality can improve the resolution of detecting surface irregularities of a finger. In a first possible implementation of the first aspect, a forming electrode is located between two adjacent drive electrodes, and a second voltage with a sign opposite to the first voltage is applied to the forming electrode. Applying the second voltage to the forming electrode enhances the upward directionality of the electric field between the drive electrode and the sensing electrode adjacent to the forming electrode, thereby improving the sensitivity of the device.

[0007] A second possible implementation of the first aspect provides: the apparatus according to the first possible implementation of the first aspect, wherein the processing circuit is further configured to generate an image having pixel values, each pixel value corresponding to a change in capacitance detected at a position where the drive electrode and the sensing electrode face each other. According to the second possible implementation of the first aspect, a clear fingerprint image can be generated using the apparatus with improved sensitivity.

[0008] A third possible implementation of the first aspect provides: the apparatus according to the first possible implementation or the second possible implementation of the first aspect, wherein the processing circuit is further configured to: on the first layer where the driving electrodes are located, replace the first group of electrodes serving as the driving electrodes with the second group of electrodes serving as the shaping electrodes, thereby interchanging between the two electrode patterns on the first layer; on the second layer where the sensing electrodes are located, replace the third group of electrodes serving as the sensing electrodes with the fourth group of electrodes serving as the shaping electrodes, thereby interchanging between the two electrode patterns on the second layer; for each of the four electrode patterns, generate an image formed by pixel values, each pixel value corresponding to a change in capacitance detected at a position where the driving electrode and the sensing electrode face each other; and combine the four generated images to obtain a combined image.

[0009] In a third possible implementation of the first aspect, the driving electrodes and part of the forming electrodes are located on the first layer, and the sensing electrodes and the remaining forming electrodes are located on the second layer. Each electrode on the first layer can act as a driving electrode when a first voltage is applied, and can act as a forming electrode when a second voltage is applied. In addition, each electrode on the second layer can act as a sensing electrode when the electrode is grounded, and can act as a forming electrode when a second voltage is applied. Therefore, the processing circuit can control the voltage applied to each electrode to interchange between the four electrode patterns. The processing circuit detects changes in capacitance at positions where the driving electrodes and the sensing electrodes are relative to each other, and therefore, the detection positions corresponding to the four electrode patterns are different from each other. Therefore, for each of the four electrode patterns, the processing circuit generates an image, and combines the four generated images to obtain a combined image having a complete set of pixel values ​​corresponding to all detection positions.

[0010] For example, the drive electrodes can be evenly distributed on a first layer, while the sensing electrodes can be evenly distributed on a second layer at a predetermined distance from the first layer. Each drive electrode can extend in one direction, and each sensing electrode can extend in another direction that intersects the first direction. Furthermore, each shaped electrode on the first layer can be located between two adjacent drive electrodes, while each shaped electrode on the second layer can be located between two adjacent sensing electrodes. In this case, for each electrode pattern, the processing circuit detects changes in capacitance at each intersection of the drive and sensing electrodes. Furthermore, for each electrode pattern, the processing circuit can generate an image based on the detected changes in capacitance and combine the four generated images to obtain a full-pixel image.

[0011] A fourth possible implementation of the first aspect provides: the apparatus according to any one of the first to third possible implementations of the first aspect, wherein the voltage signal providing the first voltage is encoded using code division multiplexing (CDM) such that the voltage signals corresponding to the drive electrodes are orthogonal to each other. According to a seventh possible implementation of the first aspect, the CDM method improves a signal-to-noise ratio (SNR) of the detection signal.

[0012] A second aspect of the embodiment provides another capacitive sensing device. In a first possible implementation of the second aspect, the device includes: a plurality of sensing electrodes to which a first voltage is applied; a plurality of shaping electrodes to which a second voltage with a sign opposite to that of the first voltage is applied, wherein each shaping electrode is located between two adjacent sensing electrodes; and a processing circuit for detecting changes in charge accumulated on each sensing electrode by the first voltage. In some examples, the electrode spacing can be in the range of 30μm to 150μm, and the device can be preferably used to generate a fingerprint image. In addition, the first voltage causes a charge to be generated on each sensing electrode during an accumulation period, and the second voltage is synchronously applied to the shaping electrode during the same period. On the other hand, the signal is read from the sensing electrode during a reading period after the accumulation period.

[0013] When a finger approaches the covering layer above the device 180, the capacitance of the finger causes an increase in the charge accumulated on the sensing electrode facing the finger. Therefore, the processing circuit can detect the finger and / or each protrusion on the surface of the finger based on the change in charge. The resolution of detecting surface irregularities of the finger may be related to the directionality of the electric field around the sensing electrode. Specifically, increasing the directionality can improve the resolution of detecting surface irregularities of the finger. In a first possible implementation of the second aspect, a forming electrode is located between two adjacent sensing electrodes, and a second voltage with an opposite sign to the first voltage is applied to the forming electrode. Applying the second voltage to the forming electrode enhances the upward directionality of the electric field around the sensing electrode, thereby improving the sensitivity of the device.

[0014] A second possible implementation of the second aspect provides: the device according to the first possible implementation of the second aspect, wherein the processing circuit is further configured to generate an image having pixel values, each pixel value corresponding to a change in charge on each sensing electrode. According to the second possible implementation of the second aspect, a clear fingerprint image can be generated using the device with improved sensitivity.

[0015] A third aspect of the embodiments provides a method for generating an image using a capacitive sensing device, the capacitive sensing device comprising a plurality of drive electrodes arranged side by side along a first direction, a plurality of sensing electrodes arranged side by side along a second direction intersecting the first direction, a plurality of shaping electrodes, and a processing circuit. In a first possible implementation of the third aspect, the method includes: a voltage source applying a first voltage to each drive electrode; a voltage source applying a second voltage having a sign opposite to the first voltage to each shaping electrode, wherein one shaping electrode among the plurality of shaping electrodes is located between two adjacent drive electrodes; and a processing circuit generating an image based on a change in capacitance between the drive electrode and the sensing electrode. In some examples, the electrode spacing can be in a range of 30 μm to 150 μm, and the device can be preferably used to generate a fingerprint image. Furthermore, the first voltage and the second voltage can be applied to the drive electrode and the shaping electrode, respectively, during a predetermined drive period to synchronously drive the drive electrode and the shaping electrode. Furthermore, reading signals from the sensing electrodes is performed during a predetermined read period that is different from the drive period.

[0016] When a first voltage is applied to the drive electrode, an electric field is generated between the drive electrode and the sensing electrode, and the sensing electrode receives charge from the drive electrode. In addition, when a finger is located on the cover layer above the device, the finger causes the electric field to change and reduces the mutual capacitance between the drive electrode and the sensing electrode. The resolution of detecting surface irregularities of a finger may be related to the directionality of the electric field between adjacent drive electrodes and sensing electrodes. Specifically, increasing the directionality can improve the resolution of detecting surface irregularities of a finger. In a first possible implementation of the third aspect, a forming electrode is located between two adjacent drive electrodes, and a second voltage with an opposite sign to the first voltage is applied to the forming electrode. Applying the second voltage to the forming electrode enhances the upward directionality of the electric field between the drive electrode and the sensing electrode adjacent to the forming electrode, thereby improving the sensitivity of the device.

[0017] A second possible implementation of the third aspect provides: according to the method of the first possible implementation of the third aspect, wherein the processing circuit generating an image based on the change in capacitance specifically includes generating an image having pixel values, each pixel value corresponding to a change in capacitance at a position where the drive electrode and the sensing electrode oppose each other. According to the second possible implementation of the third aspect, a clear fingerprint image can be generated using a device with improved sensitivity.

[0018] A third possible implementation of the third aspect provides: the method according to the first possible implementation or the second possible implementation of the third aspect, further comprising: a processing circuit changing a first group of electrodes serving as drive electrodes and a second group of electrodes serving as forming electrodes to form a plurality of electrode patterns, wherein the processing circuit generating an image based on the change in capacitance specifically comprises: generating an image having a pixel value for each electrode pattern on the drive layer and the second layer, each pixel value corresponding to a change in capacitance at positions where the drive electrode and the sensing electrode are relative to each other; and combining the four images.

[0019] In a third possible implementation of the third aspect, the driving electrodes and part of the forming electrodes are located on the first layer, and the sensing electrodes and the remaining forming electrodes are located on the second layer. Each electrode on the first layer can act as a driving electrode when a first voltage is applied, and can act as a forming electrode when a second voltage is applied. In addition, each electrode on the second layer can act as a sensing electrode when the electrode is grounded, and can act as a forming electrode when a second voltage is applied. Therefore, the processing circuit can control the voltage applied to each electrode to interchange between the four electrode patterns. The processing circuit detects changes in capacitance at positions where the driving electrodes and the sensing electrodes are relative to each other, and therefore, the detection positions corresponding to the four electrode patterns are different from each other. Therefore, for each of the four electrode patterns, the processing circuit generates an image, and combines the four generated images to obtain a combined image having a complete set of pixel values ​​corresponding to all detection positions.

[0020] A fourth possible implementation of the third aspect provides: the method according to any one of the first to third possible implementations of the third aspect, further comprising: the processing circuit encoding the voltage signal providing the first voltage in a CDM manner, such that the voltage signals corresponding to the drive electrodes are orthogonal to each other. According to a fifth possible implementation of the third aspect, the CDM manner improves the SNR of the detection signal.

[0021] A fourth aspect of the embodiment provides: a method for generating an image using a capacitive sensing device, the capacitive sensing device having a plurality of sensing electrodes, a plurality of forming electrodes, and a processing circuit. In a first possible implementation of the fourth aspect, the method includes: a voltage source applying a first voltage to each sensing electrode; a voltage source applying a second voltage having a sign opposite to the first voltage to each forming electrode, wherein each forming electrode is located between two adjacent sensing electrodes; and a processing circuit generating an image based on a change in charge accumulated on each sensing electrode by the first voltage. In some examples, the electrode spacing can be in the range of 30 μm to 150 μm, and the device can be preferably used to generate a fingerprint image. In addition, the first voltage causes a charge to be generated on each sensing electrode during an accumulation period, and the second voltage is synchronously applied to the forming electrode during the same period. On the other hand, reading the signal from the sensing electrode is performed during a reading period after the accumulation period.

[0022] When a finger approaches the covering layer above the device 180, the capacitance of the finger causes an increase in the charge accumulated on the sensing electrode facing the finger. Therefore, the processing circuit can detect the finger and / or each protrusion on the surface of the finger based on the change in charge. The resolution of detecting surface irregularities of the finger may be related to the directionality of the electric field around the sensing electrode. Specifically, increasing the directionality can improve the resolution of detecting surface irregularities of the finger. In a first possible implementation of the fourth aspect, the forming electrode is located between two adjacent sensing electrodes, and a second voltage with an opposite sign to the first voltage is applied to the forming electrode. Applying the second voltage to the forming electrode enhances the upward directionality of the electric field around the sensing electrode, thereby improving the sensitivity of the device.

[0023] A second possible implementation of the fourth aspect provides: according to the method of the first possible implementation of the fourth aspect, wherein the processing circuit generating an image based on the change in charge specifically includes generating an image having pixel values, each pixel value corresponding to the change in charge on each sensing electrode. According to the second possible implementation of the fourth aspect, a clear fingerprint image can be generated using a device with improved sensitivity.

[0024] A fifth aspect of the embodiments provides: a device, such as a mobile phone, a smartphone, a tablet computer, a personal computer, a digital camera, a navigation system, etc., comprising: the apparatus according to any possible implementation of the first aspect; a cover layer covering the apparatus; and a display module located below the apparatus. In one possible implementation of the fifth aspect, the cover layer may have a thickness of approximately 300 μm or greater.

[0025] A sixth aspect of the embodiments provides: a device, such as a mobile phone, a smartphone, a tablet computer, a personal computer, a digital camera, a navigation system, etc., comprising: the apparatus according to any possible implementation of the second aspect; a cover layer covering the apparatus; and a display module located below the apparatus. In one possible implementation of the sixth aspect, the cover layer may have a thickness of approximately 300 μm or greater.

[0026] A seventh aspect of the embodiments provides: a non-transitory computer-readable storage medium storing a program that causes a computer to execute the method according to any one of the possible implementations of the third aspect. An eighth aspect of the embodiments provides: a non-transitory computer-readable storage medium storing a program that causes a computer to execute the method according to any one of the possible implementations of the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An example of a device having a capacitive sensing device for fingerprint sensing provided by the first embodiment of the present disclosure is shown;

[0028] Figures 2A to 2C A cross-sectional view of a device provided by a first embodiment of the present disclosure is shown;

[0029] Figure 3 An example of an electrode layout in the device provided by the first embodiment of the present disclosure is shown;

[0030] Figure 4A is a schematic diagram for describing the arrangement of sensing electrodes and shaping electrodes in a device according to the first embodiment of the present disclosure;

[0031] Figure 4B shows waveforms of voltages applied to the sensing electrodes and the shaping electrodes in the device provided by the first embodiment of the present disclosure;

[0032] Figure 5 is a schematic block diagram for describing elements of a device provided in a first embodiment of the present disclosure;

[0033] Figure 6A and Figure 6B is a schematic diagram provided in accordance with the first embodiment of the present disclosure for describing an electrode pattern formed by sensing electrodes and forming electrodes in a device;

[0034] Figure 7A and Figure 7B is a schematic diagram provided in accordance with the first embodiment of the present disclosure for describing an electrode pattern formed by sensing electrodes and forming electrodes in a device;

[0035] Figure 8 The first embodiment of the present disclosure provides a method for describing the combination of Figures 6A to 7B Schematic diagram of the process of four images corresponding to the four electrode patterns shown;

[0036] Figure 9 is a flowchart for describing a method for generating an image by a device, provided by the first embodiment of the present disclosure;

[0037] Figure 10 shows an example of an electrode layout provided by a first variation of the first embodiment of the present disclosure;

[0038] Figure 11 is a schematic diagram provided by the second variation of the first embodiment of the present disclosure for describing an implementation method of the apparatus on a device;

[0039] Figure 12 is a schematic diagram for describing a method for encoding voltage pulses applied to sensing electrodes, provided by the first embodiment of the present disclosure;

[0040] Figure 13 An example of an electrode layout in a device provided by a second embodiment of the present disclosure is shown;

[0041] Figure 14A and Figure 14B is a schematic diagram for describing the arrangement of sensing electrodes and shaping electrodes in a device according to a second embodiment of the present disclosure;

[0042] Figure 15A and Figure 15B is a schematic diagram provided in accordance with a second embodiment of the present disclosure for describing an electrode pattern formed by sensing electrodes and forming electrodes in a device;

[0043] Figure 16A and Figure 16B is a schematic diagram provided in accordance with a second embodiment of the present disclosure for describing how sensitivity is improved by applying a shaping voltage;

[0044] Figure 17A and Figure 17B shows an example of an electrode layout in a device provided by a variation of the second embodiment of the present disclosure;

[0045] Figure 18 is a schematic block diagram for describing elements of a device provided in accordance with a third embodiment of the present disclosure; and

[0046] Figure 19 FIG. 3 is a schematic diagram for describing the arrangement of sensing electrodes and shaping electrodes in a device according to the third embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] The technical solutions of various embodiments will be described below in conjunction with the accompanying drawings. It should be understood that the embodiments described below are only some of the embodiments related to the present disclosure, and not all of them. It should be noted that all other embodiments that can be obtained by those skilled in the art based on the embodiments described below without inventive effort are within the scope of protection of the present disclosure.

[0048] (First Embodiment) The first embodiment of the present disclosure is described below. The first embodiment of the present disclosure relates to a device having a capacitive sensing device such as a capacitive FPS. For example, the device may be a mobile phone, a smartphone, a tablet computer, a personal computer, a digital camera, a navigation system, or the like.

[0049] Figure 1 An example of a device having a capacitive sensing device for fingerprint sensing provided by the first embodiment of the present disclosure is shown. Figure 1 The device 10 shown is a full screen display type device, wherein the display panel 11 covers almost the entire front face of the device 10. Figure 1 As shown, there is a sensing area 11a for detecting fingerprints on the display panel 11. When the finger FG is located on the sensing area 11a, the device 10 can perform fingerprint detection and fingerprint authorization according to the identification information.

[0050] The following combination Figures 2A to 2C The layer structure of the device 10 around the sensing area 11a is depicted. Figures 2A to 2C The device 10 is shown along Figure 1 The cross-sectional view of the II-II line is shown. Figure 2A In the example shown in FIG. 1 , the device 10 has a cover layer 21, an FPS / touch sensor 22, and a display module 23. The cover layer 21 is a transparent glass or film and covers the FPS / touch sensor layer 22. The FPS / touch sensor layer 22 may include at least one sensor used as an FPS and / or a touch sensor. The FPS / touch sensor layer 22 includes a capacitive sensing device described below. The display module 23 may be an organic light emitting diode (OLED), a liquid crystal display (LCD), etc., and is located below the FPS / touch sensor layer 22. The device 10 may also include a display such as Figure 2B and Figure 2C With respect to the polarizer 24 shown, these variations are possible within the scope of the first embodiment of the present disclosure.

[0051] The following combination Figures 3 to 8 A capacitive sensing device for generating a fingerprint image provided by a first embodiment of the present disclosure is described.

[0052] Figure 3FIG. 1 shows an example of an electrode layout in a device provided by the first embodiment of the present disclosure. Figure 3 As shown, the device includes electrodes evenly distributed on a first layer L1 and electrodes evenly distributed on a second layer L2 positioned a predetermined distance from the first layer L1. Each electrode on the first layer L1 extends in one direction, while each electrode on the second layer L2 extends in another direction that intersects the first direction. In this example, a voltage pulse can be applied to at least some of the electrodes on the first layer L1, and at least some of the electrodes on the second layer L2 can receive charge from the electrodes on the first layer L1.

[0053] In the first embodiment of the present disclosure, a first group of electrodes on the first layer L1 serve as drive electrodes (TX) to which a first voltage is applied, and a second group of electrodes on the first layer L1 serve as forming electrodes (FX) to which a second voltage is applied. Furthermore, a third group of electrodes on the second layer L2 serve as sensing electrodes (RX) to receive charge from the drive electrodes, and a fourth group of electrodes on the second layer L2 serve as forming electrodes (FX) to which the second voltage is applied. Each forming electrode (FX) on the first layer L1 is located between two adjacent drive electrodes (TX), and each forming electrode (FX) on the second layer L2 is located between two adjacent sensing electrodes (RX).

[0054] Figure 4A The arrangement of the sensing electrodes and the shaping electrodes in the device provided by the first embodiment of the present disclosure is shown. Figure 4A In the example of FIG, the driving electrodes (TX) and the shaping electrodes (FX) are alternately arranged on the substrate and covered by a cover layer such as a transparent glass or film. Optionally, the cover layer may also cover the electrodes on the second layer (L2).

[0055] Figure 4B FIG. 3 shows the waveform of the voltage applied to the sensing electrode and the shaping electrode in the device provided by the first embodiment of the present disclosure. Figure 4B In the figure, the first voltage V1 represents the amplitude of the first voltage pulse (TX voltage pulse) applied to the driving electrode (TX), and the second voltage V2 represents the amplitude of the second voltage pulse (FX voltage pulse) applied to the shaping electrode (FX). In each time period, the second voltage V2 has a sign opposite to that of the first voltage V1. The first voltage V1 and the second voltage V2 are applied to the driving electrode and shaping electrode, respectively, during a predetermined driving period to synchronously drive the driving electrode and shaping electrode. On the other hand, signals are read from the sensing electrodes during a predetermined reading period, which is different from the driving period.

[0056] When a first voltage V1 is applied to the drive electrode (TX), an electric field is generated between the drive electrode (TX) and the sensing electrode (RX), causing the sensing electrode (RX) to receive charge from the drive electrode (TX). When a finger FG is placed on the cover layer 21, the finger FG changes the electric field and reduces the mutual capacitance between the drive electrode (TX) and the sensing electrode (RX).

[0057] The resolution of detecting surface irregularities of the finger FG is related to the directionality of the electric field generated between the opposing drive electrode (TX) and sensing electrode (RX). Specifically, increasing this directionality can improve the resolution of detecting surface irregularities of the finger FG. Applying the second voltage V2 to the shaping electrode (FX) enhances the upward directionality of the electric field between the opposing drive electrode (TX) and sensing electrode (RX). This can improve the sensitivity of the device.

[0058] The following combination Figure 5 The elements included in the apparatus provided by the first embodiment of the present disclosure are described. Figure 5 5 is a schematic block diagram of components of a device provided by the first embodiment of the present disclosure. The capacitive sensing device 50 is an example of the device provided by the first embodiment of the present disclosure.

[0059] like Figure 5 As shown, the device 50 includes a plurality of driving electrodes 51a, 51b, 51c, ..., a plurality of sensing electrodes 52a, 52b, 52c, ..., a plurality of shaping electrodes 53a, 53b, 53c, ..., a voltage source 54, a processing circuit 55, a detector 56 and a memory 57.

[0060] The processing circuit 55 controls the voltage source 54 to apply a first voltage V1 to each driving electrode and a second voltage V2 to each forming electrode. The processing circuit 55 can be an integrated circuit (IC) called a touch IC implemented in a touch panel, or a processor such as a central processing unit (CPU), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC). The processing circuit 55 is connected to a memory 57, such as a read-only memory (ROM), a random access memory (RAM), a flash memory, a solid-state drive (SSD), or a hard disk drive (HDD). The memory 57 can store programs that enable the processing circuit 55 to control the operation of the device 50.

[0061] Furthermore, processing circuit 55 controls detector 56 to detect changes in capacitance between the drive and sensing electrodes based on the charge received by the sensing electrodes from the drive electrodes. Furthermore, processing circuit 55 generates an image having pixel values, each corresponding to a change in capacitance detected at each intersection of the drive and sensing electrodes. Alternatively, processing circuit 55 can control voltage source 54 to change the electrode patterns on first layer L1 and second layer L2, and generate another image based on the changes in capacitance detected at each intersection of the drive and sensing electrodes.

[0062] Specifically, the processing circuit 55 may replace the first group of electrodes serving as the driving electrodes (TX) on the first layer L1 with the second group of electrodes serving as the shaping electrodes (FX). Furthermore, the processing circuit 55 may replace the third group of electrodes serving as the sensing electrodes (RX) on the second layer L2 with the fourth group of electrodes serving as the shaping electrodes (FX).

[0063] The swapping on the first layer L1 provides Figure 6A The first pattern shown is Figure 6B Interchange between the second patterns shown. Figure 6A and Figure 6B is a schematic diagram for describing the electrode pattern formed by the sensing electrodes and the forming electrodes in the device provided by the first embodiment of the present disclosure. Similarly, the swap on the second layer L2 provides Figure 7A The third pattern shown is Figure 7B Interchange between the fourth pattern shown. Figure 7A and Figure 7B 1 is a schematic diagram for describing an electrode pattern formed by sensing electrodes and forming electrodes in a device according to the first embodiment of the present disclosure. Therefore, the processing circuit 55 can switch between the first pattern to the fourth pattern.

[0064] For each of the first to fourth patterns, the processing circuit 55 generates an image based on the change in capacitance detected at the intersection of the driving electrode and the sensing electrode, and stores the first to fourth images corresponding to the first to fourth patterns, respectively, in the memory 57. Since the pixels forming the image may be obtained only at the intersection of the driving electrode and the sensing electrode (see Figures 6A to 7B Therefore, the first to fourth images are as follows Figure 8 shown. Figure 8 The first embodiment of the present disclosure provides a method for describing the combination of Figures 6A to 7B Schematic diagram of the process of four images corresponding to the four electrode patterns shown. In order to complete the fingerprint image, the processing circuit 55 combines the first image to the fourth image to generate a full pixel image of the fingerprint, such as Figure 8 shown.

[0065] (Method for generating full pixel image) Figure 9 An example of a method for generating a fingerprint image provided by the first embodiment of the present disclosure is described. Figure 9 1 is a flowchart for describing an example of a method for generating an image by a device, provided in the first embodiment of the present disclosure.

[0066] In step S11, the processing circuit 55 processes the first pattern (see Figure 6A ) captures a first image based on the outputs of the sensing electrodes (RX lines) in the apparatus 50. For example, the processing circuit 55 controls the voltage source 54 to apply a first voltage V1 to each driving electrode and a second voltage V2 to each shaping electrode, so that the electrodes in the apparatus 50 form a first pattern. Furthermore, the processing circuit 55 controls the detector 56 to detect changes in capacitance between the driving electrodes and the sensing electrodes based on the outputs of the sensing electrodes, and generates an image having pixel values, each pixel value corresponding to a change in capacitance at the intersection of the driving electrode and the sensing electrode.

[0067] In step S12, the processing circuit 55 controls the voltage source 54 to switch the driving electrodes (TX lines) to the shaping electrodes (FX lines) on the first layer L1, so as to change the first pattern to the second pattern (see FIG. Figure 6B ). Further, the processing circuit 55 captures a second image according to the outputs of the sensing electrodes (RX lines) in the second pattern.

[0068] In step S13, the processing circuit 55 controls the voltage source 54 to switch the driving electrodes (TX lines) to the shaping electrodes (FX lines) on the first layer L1 and the second layer L2 to change the second pattern to the third pattern (see FIG. Figure 7A ). Further, the processing circuit 55 captures a third image according to the outputs of the sensing electrodes (RX lines) in the third pattern.

[0069] In step S14, the processing circuit 55 controls the voltage source 54 to switch the driving electrode (TX line) to the shaping electrode (FX line) on the second layer L2, so as to change the pattern from the third pattern to the fourth pattern (see FIG. Figure 7B ). Further, the processing circuit 55 captures a fourth image according to the outputs of the sensing electrodes (RX lines) in the fourth pattern.

[0070] In step S15, the processing circuit 55 combines the first image to the fourth image to generate a full-pixel image. When the process of step S15 is completed, Figure 9 The series of processes shown ends.

[0071] (First modification of the first embodiment) Figure 10 The first modification of the first embodiment of the present disclosure has been described. Figure 10 An example of an electrode layout provided by the first variation of the first embodiment of the present disclosure is shown. Figure 10 As shown, the sensing electrodes (RX lines) and / or the driving electrodes can be made of a metal mesh. In this case, to make each sensing electrode less conspicuous, a dummy mesh is preferably arranged between two adjacent sensing electrodes. The use of a metal mesh can reduce the resistance of the electrodes.

[0072] (Second modification of the first embodiment) Figure 11 A second modification of the first embodiment of the present disclosure is described. Figure 11 This is a schematic diagram provided by the second variation of the first embodiment of the present disclosure for describing an implementation method of the apparatus on a device.

[0073] As above combined Figures 2A to 2C As described above, the device provided by the first embodiment of the present disclosure can be installed in the FPS / touch sensor layer 22 on the display module 23 (external embedded type). On the other hand, the device provided by the first embodiment of the present disclosure can be directly implemented in a display such as an OLED, such as Figure 11 As shown (surface-embedded). In this case, the electrodes for the TX line and / or FX line can be arranged on a thin film encapsulation (TFE) structure. In addition, the electrodes for the RX line and / or FX line can be arranged on an insulating layer on the TX line and covered with a protective layer.

[0074] (Encoding method) Figure 12 A method of encoding the voltage pulses applied to the drive electrodes is described. Figure 12 3 is a schematic diagram for describing a method for encoding voltage pulses applied to sensing electrodes according to the first embodiment of the present disclosure.

[0075] like Figure 12 As shown, the voltage signal providing the first voltage V1 can be encoded in a code division multiplexing (CDM) manner so that the voltage signals applied to different driving electrodes are orthogonal to each other. Figure 12 In the example shown in FIG1 , when pulses TX1 through TX4 are applied to lines TX1 through TX4, respectively, four RX outputs are obtained: 3.8, 0.2, -0.2, and 0.2. In this case, processing circuit 55 performs decoding processing according to equation (1) below, obtaining an output signal of 0.8 (0.8 = 4 - 3.2). Using CDM improves the signal-to-noise ratio (SNR) of the detection signal.

[0076]

[0077] (Second embodiment) Figure 13 to Figure 1 6 describes the second embodiment of the present disclosure.

[0078] Figure 13 FIG. 2 shows an example of an electrode layout in a device according to a second embodiment of the present disclosure. In the second embodiment of the present disclosure, the electrodes on the first layer L1 are rectangular and arranged in a tile shape. Figure 13 The cross-sectional view taken along line AA is as follows Figure 14A As shown, the transparent view observed from above the electrodes on the first layer L1 and the second layer L2 is as shown in FIG. Figure 14B shown. Figure 14A and Figure 14B is a schematic diagram provided in accordance with the second embodiment of the present disclosure for describing the arrangement of sensing electrodes and shaping electrodes in a device.

[0079] exist Figure 14A In the example, drive electrodes (TX) and shaping electrodes (FX) are alternately arranged on a substrate and covered by a cover layer such as transparent glass or a film. Furthermore, adjacent drive electrodes (TX) are connected by a bridge wire (TX bridge). Thus, the interconnected drive electrodes are arranged side by side along a first direction intersecting the second direction extending from the sense electrodes (RX). Similarly, adjacent shaping electrodes (FX) are connected by a bridge wire (FX bridge), and the interconnected shaping electrodes are arranged side by side along the first direction.

[0080] like Figure 14B As shown, the interconnected driving electrodes are arranged along a first direction ( Figure 13 Similarly, the interconnected shaped electrodes form FX lines along the first direction. A first voltage V1 (see FIG. 1 ) is applied to the TX lines. Figure 4B ), a second voltage V2 is applied to the FX line (see Figure 4B ). Optionally, part of the electrodes on the second layer L2 can be used as shaped electrodes as in the first embodiment of the present disclosure.

[0081] Optionally, the processing circuit 55 may swap the first set of electrodes that are respectively driving electrodes (TX lines) with the second set of electrodes that are respectively shaping electrodes (FX lines) on the first layer L1. The swapping between the TX lines and the FX lines provides Figure 15A and Figure 15B Interchange between the two electrode patterns shown. Figure 15A and Figure 15B This is a schematic diagram illustrating the electrode pattern formed by the sensing electrodes and shaping electrodes in the device, according to the second embodiment of the present disclosure. Because the TX and RX lines of these two electrode patterns intersect at different points, processing circuit 55 controls voltage source 54 to interchange the two electrode patterns. Based on the capacitance changes at each intersection of the TX and RX lines, two images corresponding to the two electrode patterns are generated. Furthermore, processing circuit 55 combines the two images to generate a full-pixel image.

[0082] The following combination Figure 16A and Figure 16B Improving sensitivity by applying a shaped voltage is described. Figure 16A and Figure 16B 2 is a schematic diagram provided in accordance with the second embodiment of the present disclosure for describing how sensitivity is improved by applying a shaping voltage.

[0083] exist Figure 16A In the example shown in FIG1 , the distance H between the electrode surface on the first layer L1 and the metal sample on the cover layer is 700 μm, the electrode spacing on the first layer L1 can be in the range of 30 μm to 150 μm, and the width of the metal sample is 100 μm. Under these conditions, the capacitance distribution detected is as follows: Figure 16B As shown. Figure 16B In FIG, the solid line represents the capacitance distribution under the first condition that V2 is equal to -0.9 times V1, the dashed line represents the capacitance distribution under the second condition that V2 is equal to -0.5 times V1, and the dotted line represents the capacitance distribution under the third condition that V2 is equal to V1. The third condition corresponds to the condition of the existing FPS. Figure 16BAs clearly shown, the width W1 of the solid line is narrower than the width W0 of the dashed line. This indicates that applying a second voltage V2, opposite in sign to the first voltage, to the FX line improves the resolution of detecting surface irregularities of an object located on the cover layer. Furthermore, a comparison between the solid and dashed lines shows that as the magnitude of V1 approaches that of V2, the resolution increases. This trend is independent of the electrode shape and holds true even in the first embodiment of the present disclosure.

[0084] (Variation of the second embodiment) Figure 17A and Figure 17B A modification of the second embodiment of the present disclosure is described. Figure 17A and Figure 17B An example of an electrode layout in a device provided by a variation of the second embodiment of the present disclosure is shown. Figure 17A As shown in FIG, the driving electrodes, the sensing electrodes and the shaping electrodes are arranged on one layer. Figure 17B The TX bridges shown are connected to each other and form TX lines in the horizontal direction. Similarly, the shaped electrodes connected to each other form FX lines in the horizontal direction. On the other hand, the shaped electrodes connected to each other form RX lines in the vertical direction. As in the first and second embodiments of the present disclosure, a first voltage V1 (see FIG. 1 ) is applied to the TX lines. Figure 4B ), a second voltage V2 is applied to the FX line (see Figure 4B ). The above-mentioned electrode layout may be within the scope of the second embodiment of the present disclosure.

[0085] (Third embodiment) Figure 18 and Figure 19 A third embodiment of the present disclosure is described. The third embodiment of the present disclosure relates to a self-capacitance type FPS.

[0086] Figure 18 : is a schematic block diagram of the components of the device provided in the third embodiment of the present disclosure. Figure 18 As shown, the device 180 includes a plurality of sensing electrodes 181a, 181b, 181c, ..., a plurality of shaping electrodes 182a, 182b, 182c, ..., a voltage source 183, a processing circuit 184, a detector 185 and a memory 186.

[0087] Processing circuit 184 controls voltage source 183 by applying a first voltage V1 to accumulate charge on each sensing electrode and applies a second voltage V2 to each shaping electrode. Processing circuit 184 can be a touch IC, such as implemented in a touch panel, or a processor such as a CPU, FPGA, or ASIC. Processing circuit 184 is connected to memory 186, such as ROM, RAM, flash memory, SSD, or HDD. Memory 186 can store programs that enable processing circuit 184 to control the operation of device 180.

[0088] Furthermore, processing circuit 184 controls detector 185 to read the charge accumulated on each sensing electrode. When a finger approaches the overlay above device 180, the capacitance of the finger causes an increase in the charge accumulated on the sensing electrodes facing the finger. Thus, processing circuit 184 can detect the finger and / or each protrusion on the finger surface based on the change in charge. Furthermore, processing circuit 184 generates an image with pixel values, each corresponding to a change in charge accumulated at each shaped electrode location.

[0089] The shaped electrode can be Figure 19 Arrangement shown. Figure 19 is a schematic diagram for describing the arrangement of sensing electrodes and forming electrodes in a device provided by the third embodiment of the present disclosure. Figure 19 In the example of FIG, each branch of the shaped electrode is located between two adjacent sensing electrodes. Figure 19 An integrally formed shaped electrode is shown, but branches of the shaped electrode may be connected by bridge wires.

[0090] The above disclosure only discloses exemplary embodiments and is not intended to limit the scope of protection of the present invention. It should be understood by those skilled in the art that all or part of other embodiments and modifications that can be obtained according to the scope of the claims of the present invention should certainly fall within the scope of the present invention.

Claims

1. A capacitive sensing device, characterized in that: include: a plurality of driving electrodes to which a first voltage is applied, wherein the plurality of driving electrodes are arranged side by side along a first direction; a plurality of sensing electrodes arranged side by side along a second direction intersecting the first direction; a plurality of shaped electrodes to which a second voltage having a sign opposite to that of the first voltage is applied, wherein one of the plurality of shaped electrodes is located between two adjacent driving electrodes; and a processing circuit for detecting a change in capacitance between the driving electrode and the sensing electrode; The processing circuit is further configured to: on the first layer where the driving electrodes are located, replace the first group of electrodes serving as the driving electrodes with the second group of electrodes serving as the shaping electrodes; and on the second layer where the sensing electrodes are located, replace the third group of electrodes serving as the sensing electrodes with the fourth group of electrodes serving as the shaping electrodes; The processing circuit is further configured to generate an image having pixel values, each pixel value corresponding to a change in the capacitance detected at a position where the driving electrode and the sensing electrode are opposite to each other.

2. The device according to claim 1, characterized in that The processing circuit is further configured to: On the first layer where the driving electrodes are located, the first group of electrodes serving as the driving electrodes are exchanged with the second group of electrodes serving as the shaping electrodes, so as to perform an exchange between the two electrode patterns on the first layer; On the second layer where the sensing electrodes are located, the third group of electrodes serving as the sensing electrodes are replaced with the fourth group of electrodes serving as the forming electrodes, so as to perform an exchange between the two electrode patterns on the second layer; generating, for each of the four electrode patterns, an image formed of pixel values, each pixel value corresponding to a change in the capacitance detected at a position where the drive electrode and the sense electrode face each other; and The four generated images are combined to obtain a combined image.

3. The device according to claim 1 or 2, characterized in that The voltage signal providing the first voltage is encoded in a code division multiplexing (CDM) manner, so that the voltage signals corresponding to the driving electrodes are orthogonal to each other.

4. A capacitive sensing device, characterized in that: The capacitive sensing device is a self-capacitive type, comprising: a plurality of sensing electrodes to which a first voltage is applied; a plurality of shaped electrodes, to which a second voltage having a sign opposite to that of the first voltage is applied, wherein each shaped electrode is located between two adjacent sensing electrodes; and a processing circuit configured to detect a change in charge accumulated on each sensing electrode by the first voltage; The processing circuit is further configured to generate an image having pixel values, each pixel value corresponding to a change in the charge read from each sensing electrode.

5. A method for generating an image by means of a capacitive sensing device, characterized in that The capacitive sensing device comprises a plurality of driving electrodes arranged side by side along a first direction, a plurality of sensing electrodes arranged side by side along a second direction intersecting the first direction, a plurality of shaping electrodes, and a processing circuit, and the method comprises: The voltage source applies a first voltage to each driving electrode; The voltage source applies a second voltage with a sign opposite to the first voltage to each shaping electrode, wherein one shaping electrode among the plurality of shaping electrodes is located between two adjacent driving electrodes; and The processing circuit generates an image according to the change of the capacitance between the driving electrode and the sensing electrode; The method further comprises: On the first layer where the driving electrodes are located, the first group of electrodes serving as the driving electrodes are replaced with the second group of electrodes serving as the shaping electrodes; on the second layer where the sensing electrodes are located, the third group of electrodes serving as the sensing electrodes are replaced with the fourth group of electrodes serving as the shaping electrodes; Generating, by the processing circuit, an image according to the change in capacitance includes generating an image having pixel values, each pixel value corresponding to the change in capacitance at a position where the driving electrode and the sensing electrode are opposite to each other.

6. The method according to claim 5, characterized in that Also includes: The processing circuit changes the first group of electrodes serving as the driving electrodes and the second group of electrodes serving as the shaping electrodes to form a plurality of electrode patterns; The processing circuit generating an image according to the change of the capacitance specifically includes: For each electrode pattern on the first and second layers, an image having pixel values ​​is generated, each pixel value corresponding to a change in the capacitance at a position where the drive electrode and the sense electrode face each other; and all generated images are combined.

7. The method according to claim 5 or 6, characterized in that Also includes: The processing circuit encodes the voltage signal providing the first voltage in a code division multiplexing (CDM) manner, so that the voltage signals corresponding to the driving electrodes are orthogonal to each other.

8. A method for generating an image by means of a capacitive sensing device, characterized in that The capacitive sensing device is a self-capacitive type, and comprises a plurality of sensing electrodes, a plurality of shaping electrodes, and a processing circuit. The method comprises: The voltage source applies a first voltage to each sensing electrode; The voltage source applies a second voltage having a sign opposite to that of the first voltage to each shaped electrode, wherein each shaped electrode is located between two adjacent sensing electrodes; and The processing circuit generates an image according to the change of the charge accumulated on each sensing electrode. The processing circuit generating the image specifically includes: generating an image with pixel values, each pixel value corresponding to the change of the charge read from each sensing electrode.

9. A non-transitory computer-readable storage medium, characterized in that The computer stores a program that causes a computer to execute the method according to any one of claims 5 to 7.

10. A non-transitory computer-readable storage medium, characterized in that The computer stores a program that causes a computer to execute the method according to claim 8 .

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