Method and device for signal processing of touch panel with event detector for sparse signal detection

Abstract

The signal processing device of the touch input device of the present invention comprises: a driving channel arranged in an input area of ​​a touch function; a sensor channel arranged intersecting with the driving channel and detecting a change in capacitance for the input area according to a driving signal applied to the driving channel; and a readout IC that applies the driving signal to the driving channel and receives and reads the detection result of the sensor channel, wherein the readout IC includes an event detection unit that detects an event area read as an active touch within the input area based on the detection result of the sensor channel according to a first driving signal based on compression sensing applied to the driving channel, and when the event area is detected, causes a second driving signal based on time-division multiplexing sensing to be applied to the driving channel, and a signal conversion unit that measures a capacitance signal modulated by the second driving signal corresponding to a coordinate read as an effective touch within the event area, converts it into a digital signal, and outputs it.

Description

Technology Field

[0001] The present invention relates to a method and apparatus for processing signals of a touch input device based on the detection of touch events of sparse signals, in the field of touch signal detection technology. Background Technology

[0002] Today's user interfaces (UI) have evolved from electronic control devices such as keyboards and mice to touch input devices that allow users to directly touch desired objects using their hands or pens. A representative example of this is the touch screen panel (TSP), which is commonly used in various types of products such as smartphones, tablets, and TVs.

[0003] Touch screen panels can utilize various types of touch methods, such as resistive, capacitive, electromagnetic induction, infrared, or ultrasonic methods. However, capacitive touch screen panels are the mainstream due to their stable operation under temperature changes and high detection accuracy, and demand for them continues to increase.

[0004] This capacitive touch screen panel can detect whether a touch has occurred and the location of the touch based on a change in capacitance that occurs when an input tool, such as a user's finger or an electronic pen, contacts or approaches a sensor arranged on the touch screen.

[0005] FIG. 1 is a diagram illustrating a signal processing circuit of a conventional touch screen panel. Referring to FIG. 1, a touch screen is generally configured with multiple driving channels (Drv[1]-Drv[n]) and sensor channels (sen.[1]-sen,[y]) intersecting each other. Touch information input by a user is the mutual capacitance (C), which is the parasitic capacitance between the driving channels and the sensing channels. MIt is recognized as a reading of the change of ). That is, the driver applies an excitation signal to each driving channel and C M Measuring C at the location touched by the finger M It changes. In this way, C, which is modulated by the driving signal M The difference is transmitted to a readout integrated circuit (Readout IC) through a sensor channel. The signal input to the readout integrated circuit is amplified and converted into a digital signal, which is then transmitted to a digital signal processor (DSP) to decode the information contained therein.

[0006] Here, the path of the signal detected in each column of the touch screen is C modulated by the driving signal. M Since it is read by a read integrated circuit, the value measured by the ADC can be expressed by the following formula.

[0007] [Formula 1]

[0008]

[0009] Here, is a matrix for implementing a driving signal, and is the mutual capacitance of the i-th column. It represents random noise in the circuit.

[0010] As mentioned above, the key components of a readout integrated circuit (Readout IC) are a charge amplifier (Amp), an analog-to-digital converter (ADC), and a driver, and the amount of power they consume may vary depending on performance indicators such as frame rate and signal-to-noise ratio (SNR).

[0011] While each element can be designed to minimize power individually while satisfying the required performance, there is a fundamental trade-off between frame rate and SNR and power consumption. In other words, higher frame rates and SNR yield accurate detection results but inevitably lead to higher power consumption.

[0012] Therefore, despite significant advancements in high-density circuit design technology, these circumstances alone are not yet sufficient to support market demand for larger touch screen panels driven by increased power consumption of sensors and readout circuits. This issue becomes particularly severe as the size of the touch screen panel increases, especially in systems such as mobile devices where significant energy constraints are required.

[0013] More specifically, conventional touch screen panels must operate all system elements to detect sparse signals occurring partially across the entire area, even though valid information is not provided by the touch sensor for most of the product's usage time. Consequently, a significant amount of energy is inevitably wasted due to the continuous unnecessary data conversion and transmission.

[0014] In relation to this situation, various sensing technologies for reading data from a touch sensor array have been developed, and Figure 2 illustrates a representative type of sensing technology among them.

[0015] Figure 2(a) shows a Time Division Multiplexed Sensing (TDM) method. This method is of an n × n identity matrix. Using this, driving signals are transmitted sequentially to each driving channel. Accordingly, since the following equation holds, there is no need to demodulate the modulated signals later, making the implementation relatively simple.

[0016] [Equation 2]

[0017]

[0018] However, TDM consumes significant power because every sensor in each column must perform sensing. In particular, the energy efficiency of TDM deteriorates severely as the number of sensors configured in the touchscreen increases. For example, if the number of sensors doubles while the frame rate remains fixed, the power consumption of the read integrated circuit more than doubles to read the sensors over a bandwidth twice as high while maintaining the same SNR. Therefore, it is impossible to accommodate the total energy consumption of TDM in product specifications that require large touchscreen sizes or high frame rates.

[0019] FIG. 2(b) shows Code Division Multiplexed Sensing (CDM). In this method, the applied driving signal is an n × n orthogonal matrix. Since an orthogonal matrix is ​​a transpose matrix, the signal detected by the sensor channel can be restored using the following formula.

[0020] [Equation 3]

[0021]

[0022] especially, When the components of are composed of -1, 0, and 1, it is relatively easy to implement in hardware, and for example, a Hadamard matrix can be used. As such, CDM has the advantage of reducing noise in the signal recovery stage and achieving a higher SNR when the noise is uniformly distributed.

[0023] However, just like TDM, CDM requires more sensing as the number of sensors configured on the touch screen increases, which leads to an increase in the power consumption of the amplifier and ADC of the read integrated circuit. Furthermore, referring to Fig. 2(b), the driver must continue switching the driving signal throughout the entire sensing period, so the operating power of the drive also increases drastically. Moreover, as the size of the touch screen increases, the parasitic capacitance of the driving channel of CDM increases, and for this reason, energy efficiency decreases when CDM is used in large touch screens.

[0024] As a method to improve upon the problems of the aforementioned TDM and CDM, the Compressed Sensing (CS) method illustrated in Fig. 2(c) was introduced. CS was implemented to read sparse signals from sensor channels based on the characteristic that touch occurs partially in terms of location or time. Unlike TDM, in CS, driving signals are randomly applied to each driving channel, and for this purpose, an m × n rectangular matrix (m < n) This is used. That is, when any partial touch occurs, the CS is a random combination of components as -1, 0, 1 or -1, 1. It can sense multiple rows at once. Therefore, CS reduces the number of sensing operations that must be performed per unit time compared to TDM or CDM, thereby increasing speed and saving energy consumed by the read integrated circuit.

[0025] however, Since CS is a rectangular matrix with m < n rather than a square matrix, CS requires very complex computations when recovering signals modulated by capacitance differences. In other words, because multiple signals are mixed in at once, complex signal recovery algorithms are subsequently executed, and enormous computation and time are required to minimize the theoretical guarantees for this. Accordingly, even though CS can save power consumed by the readout integrated circuit due to its characteristics, it does not bring any advantage to the energy efficiency of the overall system because the power consumed for signal recovery calculations is enormous.

[0026] In other words, CS has environmental limitations that make it usable only in high-performance computing environments. In particular, for touch screen panels applied to mobile devices, efficient energy consumption must be achieved not only during signal detection but also during the recovery process, so CS is even less suitable and, in fact, commercialization is impossible.

[0027] Therefore, new methods are required to overcome the limitations of these conventional approaches. In particular, with the widespread adoption of mobile devices, energy conservation has become a major concern in the market, and new technologies are needed to achieve superior energy efficiency in line with the increasing size of touch screens. Prior art literature

[0028] D. L. Donoho, “Compressed sensing,” IEEE Trans. Inf. Theory, vol. 52, no. 4, pp. 1289-1306, Apr. 2006. The problem to be solved

[0029] The present invention aims to solve the problems of the aforementioned prior art by providing a signal processing method and apparatus for a touch input device that first detects the presence or absence of touch activity based on compressed sensing in a touch input area, and applies time-division multiplexing sensing only to the event area where activity is detected.

[0030] However, the technical problems that this embodiment aims to solve are not limited to the technical problems described above, and other technical problems may exist. means of solving the problem

[0031] A signal processing device for a touch input device according to one embodiment of the present invention includes: a driving channel arranged in an input area of ​​a touch function; a sensor channel arranged intersecting with the driving channel and detecting a change in capacitance of the input area according to a driving signal applied to the driving channel; and a readout IC that applies the driving signal to the driving channel and receives and reads the detection result of the sensor channel.

[0032] According to one embodiment of the present invention, the readout IC includes an event detection unit that detects an event area read as an active touch within the input area based on a detection result of the sensor channel according to a first driving signal based on compression sensing applied to the driving channel, and when the event area is detected, a second driving signal based on time-division multiplexing sensing is applied to the driving channel; and a signal conversion unit that measures a capacitance signal modulated by the second driving signal corresponding to a coordinate read as an effective touch within the event area, converts it into a digital signal, and outputs it.

[0033] According to one embodiment of the present invention, the event detection unit can operate continuously while consuming power (ultra-low power) below a preset threshold.

[0034] According to one embodiment of the present invention, the signal conversion unit may be configured to operate under the condition that it does not operate while the first driving signal is applied to the driving channel and switches to the second driving signal.

[0035] A signal processing method for a touch input device according to an embodiment of the present invention comprises: a step of applying a first driving signal based on compression sensing to a driving channel arranged in an input area of ​​a touch function; a step of detecting a change in capacitance of the input area according to the first driving signal through a sensor channel arranged intersecting with the driving channel and detecting an event area read as an active touch within the input area based on the detection result; a step of applying a second driving signal based on time-division multiplexing sensing to the driving channel according to the detection of the event area; and a step of detecting a change in capacitance according to the second driving signal through the sensor channel and measuring a capacitance signal modulated by the second driving signal corresponding to a coordinate read as an effective touch within the event area based on the detection result, converting it into a digital signal, and outputting it. Effects of the invention

[0036] One embodiment of the present invention provides a touch sensing technology that prevents unnecessary power consumption and maximizes energy saving.

[0037] One embodiment of the present invention provides a touch detection technology that rapidly processes touch signals.

[0038] One embodiment of the present invention provides a touch detection technology that minimizes the complex restoration process of a touch signal.

[0039] One embodiment of the present invention provides a touch detection technology that prevents the omission and misrecognition of touch events due to non-detection.

[0040] One embodiment of the invention provides a touch sensing technology optimized for large touch screen panels.

[0041] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0042] Figure 1 is a diagram illustrating a signal processing circuit of a conventional touch screen panel. Figure 2 is a diagram illustrating a typical type of conventional touch sensing technique. FIG. 3 is a structural diagram of a signal processing device of a touch input device according to one embodiment of the present invention. Figure 4 is a structural diagram illustrating an example of a signal processing device applied to a TSP. FIGS. 5 and FIGS. 6 are materials supporting the effects according to one embodiment of the present invention. FIG. 7 is an operation flowchart of a signal processing method for a touch input device according to an embodiment of the present invention. Specific details for implementing the invention

[0043] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0044] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0045] In this specification, the term "part" includes a unit realized by hardware, a unit realized by software, and a unit realized using both. Additionally, one unit may be realized using two or more pieces of hardware, and two or more units may be realized by one piece of hardware. Meanwhile, "part" is not limited to software or hardware, and "part" may be configured to reside in an addressable storage medium or configured to run on one or more processors. Accordingly, as an example, "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and '~parts' may be implemented to play one or more CPUs within the device or secure multimedia card.

[0046] In this specification, the term "touch input device" refers collectively to electronic computing devices that provide data input functions using a human finger or an electronic pen. For example, it may include, but is not limited to, various devices that provide a touch UI, such as smartphones, touchpads, laptops, and electronic whiteboards. Embodiments of the present invention will be described with a focus on mobile devices that include touch screen panels (TSPs), which are the most widely used. However, the embodiments of the present invention are applicable to all various input devices that generate sparse signals and should be interpreted as encompassing such devices.

[0047] In addition, the term "input area" refers collectively to an area within a touch input device that provides touch input functions. For example, it may include not only the part where a touch screen or touch panel is formed within the device, but also various pointing devices such as touch keyboards and touch mice, but is not limited thereto. However, embodiments of the present invention are described with a focus on the touch screen (TSP), and other equivalent elements should also be interpreted as being included within the scope of the present invention.

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0049] FIG. 3 is a structural diagram of a signal processing device for a touch input device according to an embodiment of the present invention. Referring to FIG. 3, the signal processing device (10) includes a driving channel (210) and a sensor channel (220) arranged in an input area (200), and a readout IC (100).

[0050] A driving channel (driving Ch, 210) according to one embodiment may be a line to which a driving signal is applied to supply voltage to an input area (200) in which pixels are arranged and a touch function is provided. A plurality of driving channels (210) may be arranged side by side in one direction of the input area (200).

[0051] According to one embodiment, the sensor channel (220) is arranged in the input area (200) by intersecting with the driving channel (210). Accordingly, each point where the driving channel (210) and the sensor channel (220) intersect can be recognized as a coordinate representing a specific location in the input area (200).

[0052] When a driving signal is applied, mutual capacitance occurs between the driving channel (210) and the sensor channel (220). When an input tool, such as a finger or a stylus pen, touches a specific coordinate of the input area (200), the capacitance of that coordinate shows a difference before and after the touch. The sensor channel (220) detects this change in capacitance, and the modulated signal is transmitted to the readout IC (100).

[0053] A readout IC (100) according to one embodiment applies a driving signal to a driving channel (210) and receives a detection result from a sensor channel (220) and reads the information. Basically, when a touch occurs, the readout IC (100) reads the difference in capacitance detected by the sensor channel (220), determines whether a touch event has occurred, and then performs digitization to read a valid touch within the corresponding area.

[0054] Referring to FIG. 3, a readout IC (100) according to one embodiment includes an event detection unit (110) and a signal conversion unit (120).

[0055] According to one embodiment, the event detection unit (110) may be configured to detect a sparse signal occurring partially within the input area (200) in terms of location or time. That is, the event detection unit (110) may determine whether an event recognized as touch activation has occurred based on the detection result of the sensor channel (220), and may detect a region of interest (ROI) within the input area (200) where a touch event has occurred. Here, the region of interest is defined as an event area in terms of meaning.

[0056] According to one embodiment, in a normal state where no touch is performed, the readout IC (100) is configured to apply a first driving signal to the driving channel (210). The event detection unit (110) receives a change in capacitance within the input area (200) according to the first driving signal from the sensor channel (220), reads it, and detects the event area.

[0057] According to one embodiment, it is preferable that the first driving signal be implemented as a voltage waveform for compression sensing and applied to the driving channel (210). That is, as described above through FIG. 2(c), the first driving signal may not be applied sequentially to each driving channel (210) but may be applied arbitrarily or redundantly. Accordingly, when a partial touch occurs, one sensor channel (220) can detect signal changes at multiple coordinates at once, thereby reducing energy consumed by the readout IC (100) and shortening the reading time. Meanwhile, a more specific embodiment of the first driving signal will be described later.

[0058] According to one embodiment, the event detection unit (110) may be set to operate continuously. That is, the detection of touch activation by access or contact of an input tool and the reading of the area are performed continuously.

[0059] According to one embodiment, the event detection unit (110) may be configured to consume power below a preset threshold. The change in capacitance detected by the first driving signal is utilized only at the event detection unit (110) and is not digitized and subsequently restored to proceed to the process of deriving touch information. That is, the event detection unit (110) does not calculate the exact coordinates where a valid touch occurred and the information contained therein, but merely performs a process of detecting whether a sparse signal occurs and detecting the event area. Therefore, since the complex computational procedure of compressed sensing, which was pointed out as a limitation of the past, can be omitted, the event detection unit (110) can be operated at ultra-low power at all times.

[0060] According to one embodiment, when an event area is detected by the event detection unit (110), the readout IC (100) switches from a first driving signal to a second driving signal in response and applies it to the driving channel (210).

[0061] A signal conversion unit (120) according to one embodiment may be composed of an analog-to-digital converter (ADC) that converts an analog signal of capacitance changed by touch into a digital signal and outputs it. That is, the signal conversion unit (120) measures the voltage of the capacitance signal modulated by the second driving signal using the detection result of the sensor channel (220), and accordingly, the exact coordinates where an effective touch occurred within the event area can be read.

[0062] According to one embodiment, the signal conversion unit (120) may be configured to receive only the detection result of the sensor channel corresponding to the event area among the sensor channels (220) arranged in the input area (200) when a second driving signal is applied. Therefore, since the point where a touch occurs is detected only within the range of the event area rather than the entire input area (200), energy saving is achieved and rapid processing is possible.

[0063] According to one embodiment, it is preferable that the second driving signal be implemented as a waveform for time-division multiplexing sensing and applied to the driving channel (210) so that subsequent restoration operations are not required. That is, as described above through FIG. 2(a), the second driving signal can be applied sequentially to each driving channel (210). However, since the reading range of the signal conversion unit (120) is limited to within the event area, the excessive energy consumption and reading time, which are problems of conventional time-division multiplexing sensing, are improved.

[0064] According to one embodiment, it is preferable that the signal conversion unit (120) is configured not to operate while the first driving signal is applied to the driving channel (210), but to operate under the condition of switching to the second driving signal. That is, the signal conversion unit (120) does not consume power in an OFF state during normal times when no touch occurs, and can be switched to ON only when touch activation is detected by the approach or contact of an input tool. Therefore, unlike conventional ADCs that operated even in general situations where no valid touch occurred, digital conversion is performed only in the actual necessary sections, thereby solving the conventional problem of causing significant energy waste in the corresponding processing.

[0065] Hereinafter, embodiments of the present invention will be described more specifically through an embodiment of a representative touch screen panel (TSP). Here, for the sake of understanding, the term "input area (200)" is replaced with "touch screen (200)". FIG. 4 is a structural diagram for explaining an embodiment of a signal processing device (10) applied to a TSP.

[0066] Referring to FIG. 4, touch recognition on a touch screen (200) can proceed through the following series of processes. First, the detection of whether a touch is active and the event area by the event detection unit (110) is performed using compressed sensing. Next, the event area is read by the signal conversion unit (120) based on time-division multiplexing sensing, and accordingly, the difference in capacitance that has changed at the coordinates where the actual touch occurred is converted into a digital signal and output. Subsequently, the signal output from the signal conversion unit (120) is transmitted to the digital processor (300). The digital processor (300) includes a signal processing analysis unit (310) and an AFE controller (320), through which the signal is restored and the accurate coordinates and touch information where a valid touch occurred can be analyzed. Meanwhile, a more detailed description of the operation of the digital processor (300) is omitted as it is a known concept.

[0067] Referring to FIG. 4, the touch screen (200) may have driving channels (210) and sensor channels (220) arranged to intersect each other orthogonally. The readout IC (100) may include an event detection unit (110), a signal conversion unit (120), an amplifier (130), a driver (140), a multiplexer (150), and a quantization unit (160).

[0068] Additionally, as an embodiment, referring to FIG. 4, the sensor channel (220) is connected to the event detection unit (110) and the signal conversion unit (120), and an amplifier (130) may be additionally placed between them. Additionally, a quantization unit (160) may be further connected between the output terminal of the amplifier (130) and the input terminal of the event detection unit (110). The output terminal of the event detection unit (110) is connected to a multiplexer (150) to control the output of the multiplexer (150), and the output terminal of the multiplexer (150) may be connected to a driver (140). The output terminal of the driver (140) is connected to a driving channel (210), so that a driving signal selectively output by the multiplexer (150) can be applied to the driving channel (210). Meanwhile, a more specific embodiment of the signal processing process according to the connection relationship between each component of the present embodiment will be described later.

[0069] According to one embodiment, the driving channels (210) may be arranged longitudinally with a predetermined spacing to form a row of the touch screen (200).

[0070] According to one embodiment, the sensor channels (220) may be arranged laterally at predetermined intervals to form a column of the touch screen (200). Each point where the sensor channels (220) and the driving channels (210) intersect each other may be identified by unique coordinates on the touch screen (200). The sensor channels (220) detect the capacitance changing at each coordinate due to a touch, and the difference is transmitted to the readout IC (100).

[0071] According to one embodiment, the readout IC (100) may include a multiplexer (150) of control logic that selectively outputs a first driving signal and a second driving signal. The multiplexer (150) is normally configured to output the first driving signal by default, and may be controlled by an event detection unit (110) to output the second driving signal when an event area is detected.

[0072] According to one embodiment, the readout IC (100) may include a driver (140) connected to a multiplexer (150) and applying a driving signal output by the multiplexer (150) to a driving channel (210). That is, the voltage of the first driving signal is applied to the driving channel (210) by the driver (140), and after an event region is detected, it may be immediately switched to the voltage of the second driving signal and applied to the driving channel (210).

[0073] According to one embodiment, the readout IC (100) may include an amplifier (130). A capacitive signal modulated by a first driving signal and a second driving signal received from a sensor channel (220) may be amplified by the amplifier (130) and transmitted to an event detection unit (110) and a signal conversion unit (120), respectively.

[0074] According to one embodiment, the first driving signal is a compression sensing-based matrix ( It can be implemented randomly as ). For example, a matrix( ) can be probabilistically generated as a dense random matrix in which components are generated by a Gaussian or Bernoulli distribution.

[0075] According to one embodiment, as a system specification of the touch screen (200), the number of multiple inputs (k) that can be input with a single touch may be pre-set. In this regard, a matrix () implementing a first driving signal ) can be determined according to the number of multiple inputs (k). That is, a matrix for detecting touch activation status and event area ( ) is the existing compressed sensing matrix ( Unlike ), it is desirable to implement it as a deterministic matrix rather than an arbitrary component.

[0076] Specifically, the matrix ( Since ) is based on compressed sensing, it can be implemented as an m × n rectangular matrix (m < n). Therefore, when there is a single touch, sparse signal detection for multiple rows of the touch screen (200) can be performed by the first driving signal. Matrix ( It is desirable that ) be set to satisfy the following formula for design advantages.

[0077] [Equation 4]

[0078]

[0079] In this case, the number of rows (m) is an integer multiple of the number of multiple inputs (k).

[0080] Under the above conditions, matrix ( ) is a first area for identifying the sensor channel (220) ( A region composed of column vectors) and a second region for sparse signal detection (event detection) of compressed sensing ( It can be composed of a region consisting of column vectors) and can satisfy the following formula.

[0081] [Formula 5]

[0082]

[0083] Here, the column vector of the first region ( Similar to time-division multiplexing sensing, the i-th component can be set to 1 and the other components to 0. Also, the column vector of the second region ( ) can be set as a vector where the elements from the i-th to the (i+k)-th are -1 and all other elements are 0. For example, when k is 2, the matrix ( ) can be expressed by the following formula.

[0084] [Equation 6]

[0085]

[0086] According to Equation 6, the matrix ( ) is a column vector based on the number of multiple inputs (k) It can be designed using the components of a ternary code of -1, 0, and 1 so that ) are linearly independent. Accordingly, the event detection unit (110) can detect all sparse signals when multiple inputs are performed simply by reading whether the measurement value of the capacitance change according to the first driving signal is 0. Meanwhile, whether it is 0 is a desirable situation assuming there is no noise in the circuit, and if there is noise, whether the measurement value is similar to 0 (whether the measurement value is less than or equal to the difference from 0 that is preset) can be monitored.

[0087] Next, since the sparse signal representing a touch event is positive, the matrix ( Based on ), the sensor channel (220) activated by the event can be identified according to the sign and magnitude of the measurement value. As previously mentioned, since m < n, when k multiple inputs occur, the number of times the event detection unit (110) performs reading is reduced compared to time-division multiplexing sensing. For example, assuming that Equation 4 is satisfied, readings for m samples from n sensors can be performed. That is, the matrix ( When the first driving signal of ) is applied to the driving channel (210), when multiple inputs of k occur, the detection rate of the sensor channel (220) to be performed per unit time is This can be represented as such. Therefore, the event detection unit (110) detects touch events quickly, and an energy saving effect is induced accordingly.

[0088] According to one embodiment, using the structure of Equation 5, the matrix implementing the first driving signal is a matrix that simultaneously reads whether touch is active in at least two columns among the columns of the touch screen (200) in which the sensor channels (220) are arranged. It can be determined by ). This is, matrix( Each column vector of ) It is generated in a manner that repeats times, and accordingly Since a block consisting of columns can be considered as a single column vector, a better detection rate can be achieved compared to general compressed sensing.

[0089] Specifically, is a parameter determined by the number of multiple inputs (k) and the total number of sensor channels (220) (N). Here, the number of multiple inputs (k) and the number of sensor channels (220) (N) are pre-set as system specifications, but it is desirable to satisfy the following equation under the condition of Equation 4.

[0090] [Equation 7]

[0091]

[0092] If Equation 7 is satisfied, matrix( Each column vector of ) is the size of the matrix To create Not a number It can be repeated several times. In such cases, or A block consisting of several sensor channels (220) can be considered as one sensor channel, and a matrix ( It is possible to determine which block is activated in the same way as ). That is, the event detection unit (110) can determine whether touch is activated for a number of columns (N sensor channels) satisfying the following formula when k inputs occur, by using only m results detected according to the first driving signal.

[0093] [Equation 8]

[0094]

[0095] Accordingly, the matrix ( When the first driving signal of ) is applied to the driving channel (210), when multiple inputs of k occur, the detection rate of the sensor channel (220) to be performed per unit time is It can be represented as.

[0096] According to one embodiment, the event detection unit (110) can detect an event area where the touch is activated by only relatively simple operations such as comparison or addition, without performing complex operations for restoring the input signal. Therefore, even if a sparse signal is detected based on compression sensing, the massive power consumed in the conventional demodulation process is not required, so energy consumption can be minimized.

[0097] For example, detection of an event area may be possible simply by operating multiple sensor channels (220) simultaneously and comparing the corresponding outputs with a specific threshold value. However, while the sensor outputs have relatively few elements requiring detection, they are accompanied by high DC current. Accordingly, if multiple columns of sensors are detected simultaneously, the output DC currents are summed up, raising a high risk that the operating range of the amplifier (130) and the signal conversion unit (120) will be limited. As an embodiment to prevent this, the matrix of the first driving signal ( and ) can be designed so that the sum of the components of each row vector is 0, and the output DC currents can cancel each other out.

[0098] Specifically, according to the structural features of Equation 5, the event detection unit (110) can perform an event area detection algorithm using the measured value of the capacitance signal modulated by the first driving signal. As previously mentioned, the algorithm is a matrix ( that implements the first driving signal) and It applies equally to all of ), and below It will be explained with an example.

[0099] In this regard, the event detection unit (110) is a matrix ( It may include a quantization unit (160) that quantizes the measured value of the capacitance changed according to ) into 2-bit, or may be connected to the quantization unit (160). For example, noise ( With ) taken into account, the measured value of voltage according to the change in capacitance ( ) is a threshold value pre-set as the criterion for touch activation ( It is compared with ) and can be quantized into 4 levels through the following formula. Meanwhile, it is not limited to examples, and the threshold value ( ) can be set at least one or more times.

[0100] [Formula 9]

[0101]

[0102] Level:

[0103] The event detection unit (110) is a quantized measurement value ( Through an algorithm using ), the touch activation status of the column where each sensor channel (220) is located can be read, and the results can be combined to detect the event area. Here, the touch activation status is an indicator ( It can be output as ). For example, the i-th indicator( If the value of ) is 1, the area of ​​the touch screen (200) corresponding to the i-th column can be read as being included in the event area, and if it is 0, it can be read as inactive.

[0104] Specifically, as a first step, the event detection unit (110) has a quantized measurement value ( )at The location of a negative sample with a greater absolute value can be searched. The event detection unit (110) reads that the sensor channel (220) corresponding to the location of the searched sample is activated and the indicator ( ) can be output as 1. That is, the column in which the corresponding sensor channel (220) is arranged can be identified as being included in the event area where a sparse signal is detected. As a second step, the event detection unit (110) checks consecutive samples equal to the number of multiple touches (k) from the negative samples searched in the first step to obtain a measurement value ( Samples where ) is close to 0 can be identified. For example, the event detection unit (110) can identify the measurement value (among k consecutive negative samples from the samples searched in step 1) )this The location of a larger sample can be searched. This allows for the additional identification of an event area where the touch is activated. As a third step, if no negative samples are found in the first step, the event detection unit (110) corresponds to the range [m+1, n]. All sensors can be read as inactive. Subsequently, the event detection unit (110) quantizes the measurement value ( )at Search for the location of a larger positive sample, and identify the column of the touch screen (200) corresponding to that location as an event area, and the indicator ( ) can be output as 1.

[0105] As a result of the above algorithm, all sensor channels (220) activated according to the first driving signal are combined, and an event area read as a touch occurrence or activation within the touch screen (200) can be detected. When an event area is detected, the event detection unit (110) controls the multiplexer (150) to switch to the second driving signal, and the driver (140) can apply the second driving signal output by the multiplexer (150) to the driving channel (210).

[0106] As in the above-described embodiment, the process of the event detection unit (110) operating according to the first driving signal can be continuously performed at low power below a preset threshold. In addition, the signal conversion unit (120) does not operate in an OFF state during this process, and when an event area is detected and switched to the second driving signal, the signal conversion unit (120) operates in an ON state. Therefore, the consumption of the massive amount of energy required for the ADC is efficiently reduced.

[0107] According to one embodiment, time-division multiplexing sensing for reading valid touch coordinates within an event area rather than the entire range of the touch screen (200) may be performed. That is, when a second driving signal is applied to the driving channel (210), the signal conversion unit (120) can receive only the detection result of the sensor channel corresponding to the event area among the sensor channels (220) arranged on the touch screen (200).

[0108] Therefore, as described above, by performing time-division multiplexing sensing that does not require a signal restoration process, advantages are gained in terms of computation, while simultaneously improving the problems of low processing speed and unnecessary power waste associated with conventional time-division multiplexing sensing.

[0109] Finally, the signal conversion unit (120) measures the capacitance signal modulated by the second driving signal and passed through the amplification unit (130), and can convert it into a digital signal and output it. The output digital signal can be transmitted to a digital processor (300) to be derived as touch information.

[0110] Hereinafter, experimental data supporting the effects of the present invention will be introduced using FIGS. 5 and 6. FIGS. 5 and 6 are materials supporting the effects according to one embodiment of the present invention.

[0111] FIG. 5 is a graph showing the performance of the sensing precision (True positive rate, TPR) and recall rate (False positive rate, FPR) when signal processing accompanied by the event detection unit (110) is performed in various environments. The number of sensors used is (a) 1,000, (b) 5,000, and (c) 10,000, and the number of multiple inputs is set to 5 and 8, respectively, and the sampling rate is varied. Looking at this, it can be inferred that the lower the sampling rate, the more multiple columns can be compressed for sensing, which leads to energy savings. In addition, FIG. 5 is a result obtained at 25 dB, which is a worse environment than the signal-to-noise ratio (SNR) of 40 dB of a typical touch screen panel, and it can be inferred that the sensing combined with the event detection unit (110) is sufficiently robust against noise.

[0112] FIG. 6 is a graph comparing power consumption according to the present invention with that of the conventional TDM and CDM methods. The number of sensors used is (a) 5,000 and (b) 10,000, and the number of multiple inputs (k) is set to 5 and 8, respectively, and the power consumption is measured by varying the number of columns (m) that detect simultaneously. Meanwhile, the present invention is designed by adding the configuration of an event detection unit (110) to the existing TDM basis. The event detection unit (110) operates continuously, but when no touch event occurs, the amplifier and ADC are implemented in an OFF state. Looking at this, it can be confirmed that the signal processing device (10) of the present invention maintains a reproduction rate of 90% or more and can save up to 42 times more power compared to the conventional method.

[0113] Hereinafter, the process of the signal processing device (10) of the present invention will be summarized using FIG. 7. FIG. 7 is a flowchart of the operation of a signal processing method of a touch input device according to one embodiment of the present invention, and the contents of the overlapping embodiments are replaced by the foregoing.

[0114] In step S710, the device (10) applies a first driving signal based on compression sensing to a driving channel arranged in an input area of ​​the touch function. Meanwhile, a sensor channel is placed in the input area intersecting with the driving channel.

[0115] As an example, the device (10) can determine a matrix implementing a first driving signal according to the number of multiple inputs preset in the input area.

[0116] As an example, the device (10) may configure a matrix implementing a first driving signal with components of a ternary code of -1, 0, and 1, and determine that each column vector is independently arranged based on the number of multiple inputs and that the sum of the components of each row vector is 0.

[0117] As an example, the device (10) may determine that a matrix implementing a first driving signal simultaneously reads whether touch is active in at least two columns among the columns of an input area where sensor channels are arranged.

[0118] In step S720, the device (10) detects a change in capacitance of an input area according to a first driving signal through a sensor channel and, based on the detection result, detects an event area that is read as an active touch within the input area.

[0119] As an example, the device (10) can compare a measurement of a capacitance signal modulated by a first driving signal with at least one threshold value preset as a reference for touch activation, and detect an event area based on the level of the quantized measurement value as a result.

[0120] As an example, it is preferable that S710 and S720 are continuously performed while consuming power below a preset threshold.

[0121] In step S730, the device (10) switches from the first driving signal to a second driving signal based on time-division multiplexing sensing and applies it to the driving channel.

[0122] As an example, a multiplexer that outputs a first driving signal outputs a second driving signal under the condition that an event area is detected, and the second driving signal can be applied by a drive connected to the multiplexer.

[0123] In step S740, the device (10) detects a change in capacitance according to the second driving signal through a sensor channel. Based on the detection result, the device (10) measures the capacitance signal modulated by the second driving signal corresponding to the coordinates read as valid touches within the event area, converts it into a digital signal, and outputs it.

[0124] As an example, when a second driving signal is applied to a driving channel, the device (10) can collect only the detection result of the sensor channel corresponding to the event area among the sensor channels arranged in the input area.

[0125] As an example, the signal conversion unit of the device (10) performing S740 is preferably configured not to operate in S710 and S720, but to operate under the condition that S730 is performed.

[0126] Although the method and system of the present invention have been described in relation to specific embodiments, some or all of their components or operations may be implemented using a computer system having a general-purpose hardware architecture.

[0127] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0128] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0129] 10: Signal processing unit 100: Readout IC 110: Event detection unit 120: Signal converter 130: Amplifier 140: Driver 150: Mukx 160: Quantization section 200: Input Area (TSP) 210: Drive Channel 220: Sensor Channel 300: Digital processor 310: Signal Processing Analysis Unit 320: AFE Controller

Claims

Claim 1 A signal processing device for a touch input device comprises: a driving channel arranged in an input area of ​​a touch function; a sensor channel arranged intersecting with the driving channel and detecting a change in capacitance for the input area according to a driving signal applied to the driving channel; and a readout IC that applies the driving signal to the driving channel and receives and reads the detection result of the sensor channel, wherein the readout IC comprises: an event detection unit that detects an event area read as an active touch within the input area based on the detection result of the sensor channel according to a first driving signal based on compressed sensing applied to the driving channel, and when the event area is detected, causes a second driving signal based on time division multiplexed sensing to be applied to the driving channel; and a signal conversion unit that measures a capacitance signal modulated by the second driving signal corresponding to a coordinate read as an effective touch within the event area, converts it into a digital signal, and outputs it, wherein a matrix implementing the first driving signal is determined according to the number of multiple inputs preset in the input area. Claim 2 In claim 1, the event detection unit is a signal processing device of a touch input device that operates continuously while consuming power below a preset threshold. Claim 3 A signal processing device of a touch input device, wherein the signal conversion unit is configured to operate under the condition that it does not operate while the first driving signal is applied to the driving channel and is converted to the second driving signal. Claim 4 In claim 1, the signal conversion unit receives only the detection result of the sensor channel corresponding to the event area among the sensor channels arranged in the input area when the second driving signal is applied to the driving channel, a signal processing device of a touch input device. Claim 5 A signal processing device for a touch input device according to claim 1, wherein the readout IC comprises a multiplexer that sets the output of the first driving signal as a default setting and outputs the second driving signal according to the control of the event detection unit, and a drive that applies the driving signal output from the multiplexer to the driving channel. Claim 6 delete Claim 7 A signal processing device for a touch input device according to claim 1, wherein the matrix is ​​composed of components of a ternary code of -1, 0, and 1, and each column vector is independently arranged based on the number of multiple inputs and determined such that the sum of the components of each row vector is 0. Claim 8 A signal processing device of a touch input device, wherein, in claim 1, the matrix implementing the first driving signal is determined to simultaneously read whether touch is active in at least two columns among the columns of the input area in which the sensor channels are arranged. Claim 9 A signal processing device of a touch input device, wherein the event detection unit compares a measurement value of a capacitance signal modulated by the first driving signal with at least one threshold value preset as a standard for touch activation, and detects the event area based on the level of the quantized measurement value as a result of the comparison. Claim 10 A method for processing signals of a touch input device, comprising: a step of applying a first driving signal based on compression sensing to a driving channel arranged in an input area of ​​a touch function; a step of detecting a change in capacitance of the input area according to the first driving signal through a sensor channel arranged intersecting with the driving channel and detecting an event area read as an active touch within the input area based on the detection result; a step of applying a second driving signal based on time-division multiplexing sensing to the driving channel according to the detection of the event area; and a step of detecting a change in capacitance according to the second driving signal through the sensor channel and measuring a capacitance signal modulated by the second driving signal corresponding to a coordinate read as an effective touch within the event area based on the detection result, converting it into a digital signal, and outputting it, wherein the step of applying the first driving signal includes a step of determining a matrix implementing the first driving signal according to the number of multiple inputs preset in the input area. Claim 11 In claim 10, the step of applying the first driving signal and the step of detecting the event area are performed continuously while consuming power below a preset threshold, a signal processing method for a touch input device. Claim 12 A signal processing method for a touch input device, wherein, in claim 10, the step of converting and outputting into a digital signal is performed by a signal converter that converts an analog signal into a digital signal, and the signal converter is configured to operate under the condition that the step of converting and applying into a second driving signal is performed. Claim 13 A signal processing method for a touch input device according to claim 10, wherein the step of converting and outputting into a digital signal includes the step of collecting only the detection result of the sensor channel corresponding to the event area among the sensor channels arranged in the input area when the second driving signal is applied to the driving channel. Claim 14 A signal processing method for a touch input device according to claim 10, wherein the step of switching to and applying the second driving signal includes the step of the multiplexer that was outputting the first driving signal outputting the second driving signal under the condition that the event area is detected, and the second driving signal being applied by a drive connected to the multiplexer. Claim 15 delete Claim 16 A signal processing method for a touch input device according to claim 10, wherein the step of applying the first driving signal comprises the step of configuring the matrix with components of a ternary code of -1, 0, and 1, and determining that each column vector is independently arranged based on the number of multiple inputs and the sum of the components of each row vector is 0. Claim 17 A signal processing method for a touch input device according to claim 10, wherein the step of applying the first driving signal comprises the step of determining a matrix implementing the first driving signal to simultaneously read whether touch is active in at least two columns among the columns of the input area in which the sensor channels are arranged. Claim 18 A signal processing method for a touch input device according to claim 10, wherein the step of detecting the event region comprises comparing a measurement value of a capacitance signal modulated by the first driving signal with at least one threshold value preset as a standard for touch activation and detecting the event region based on the level of the quantized measurement value as a result of the comparison.

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