TW201430664A - Capacitive touch sensing device and detection method thereof - Google Patents

Abstract

There is provided a capacitive touch sensing device including a sensing element, a drive unit, a detection circuit and a processing unit. The sensing element has a first electrode and a second electrode configured to form a coupling capacitance therebetween. The drive unit is configured to input a drive signal to the sensing element. The detection circuit is configured to detect a detection signal coupled from the drive signal through the coupling capacitance and to modulate the detection signal respectively with two signals to generate a two-dimensional detection vector. The processing unit identifies a touch event according to the two-dimensional detection vector.

Description

Capacitive touch sensing device and detecting method thereof

The present invention relates to a touch system, and more particularly to an active capacitive touch sensing device.

A capacitive sensor typically includes a pair of electrodes for sensing a finger. When the finger is present, the amount of charge transfer between the pair of electrodes is changed, so that the presence or absence of the finger can be detected according to a voltage change. Aligning the plurality of electrode pairs into an array can form a sensing array.

1A and 1B show a schematic diagram of a conventional capacitive sensor including a first electrode 91, a second electrode 92, a driving circuit 93, and a detecting circuit 94. The driving circuit 93 is configured to input a driving signal to the first electrode 91. An electric field is generated between the first electrode 91 and the second electrode 92 to transfer charges to the second electrode 92. The detecting circuit 94 can The amount of charge transfer of the second electrode 92 is detected.

When a finger is present, for example, represented by an equal circuit 8, the finger disturbs the electric field between the first electrode 91 and the second electrode 92 to reduce the amount of charge transfer, and the detecting circuit 94 can detect The voltage value changes so that the presence of the finger can be judged.

The principle of a conventional active capacitive sensor can be referred to, for example, the US Patent Publication No. 2010/0096193 and U.S. Patent No. 6,452,514.

As shown in FIG. 1C, the detecting circuit 94 generally includes a detecting switch 941 and a detecting unit 942. The detecting unit 942 can detect the second electrode 92 during the opening of the detecting switch 941. Voltage value. However, the signal lines on the sensing arrays in different panels may have different capacitance values, and the driving signals input by the driving circuit 93 may have different phase shifts with respect to different sensing arrays. Therefore, the detection switch 941 must be calibrated for different panels during the opening period, otherwise the correct voltage value cannot be detected, and the correction step increases the manufacturing complexity.

In view of this, the present invention provides a capacitive touch sensing device that is not affected by a phase difference generated by a signal line and a detecting method thereof.

An object of the present invention is to provide a capacitive touch sensing device and a detecting method thereof, which utilize two continuous signals to modulate a detecting signal to eliminate the influence of a phase difference caused by sensing a signal line of the array.

The present invention provides a capacitive touch sensing device including a first electrode, a second electrode, a driving unit, a detecting circuit, and a processing unit. The first electrode and the second electrode are used to form a coupling capacitor. The driving unit is configured to emit a driving signal to the first electrode. The detecting circuit is coupled to the second electrode for detecting that the driving signal is coupled to the detecting signal of the second electrode through the coupling capacitor, and the detecting signal is modulated by the two signals respectively. Generate a 2D detection vector. The processing unit is configured to calculate a vector norm of the two-dimensional detection vector and compare the vector norm with a threshold to determine a touch event.

The present invention further provides a method for detecting a capacitive touch sensing device. The capacitive touch sensing device includes a sensing unit including a first electrode and a second electrode for forming a coupling capacitor. The detecting method includes: inputting a driving signal to the first electrode of the sensing unit; respectively modulating the driving signal by the two signals, and coupling the detection signal to the detecting signal of the second electrode to generate a pair of modulation signals And detecting a signal; and calculating a scale of the detected signal after the modulation and determining a touch event.

The invention further provides a capacitive touch sensing device, comprising a capacitive sensing array, a plurality of driving units, a detecting circuit and a processing unit. The capacitive sensing array comprises a plurality of sensing units arranged in an array, each sensing unit comprising a first electrode and a second electrode for forming a coupling capacitor. The driving units are coupled to the first electrodes of the sensing units for sequentially outputting a driving signal to the first electrodes. The detecting circuit is coupled to the second electrode of the sensing unit, and is configured to sequentially detect the driving signal to be coupled to the detecting signal of the second electrode through the coupling capacitor, and respectively use the two signals to modulate the detecting The signal is used to generate a pair of modulated detection signals. The processing unit determines a touch event and a touch position according to the pair of modulated detection signals.

In one embodiment, the norm of vector can be found using a coordinate rotation digital computer (CORDIC).

In one embodiment, the two signals are continuous signals, such as two continuous signals that are orthogonal or non-orthogonal to each other. For example, the two signals may be a sinusoidal signal and a cosine signal, and the phase difference therebetween may be equal to, greater than, or less than zero degrees.

In one embodiment, the drive signal can be a time varying signal, such as a periodic signal.

In one embodiment, the detection circuit further includes at least one integrator and at least one analog-to-digital conversion unit. The integrator is used to integrate the modulated detection signal. The analog-to-digital conversion unit is configured to digitize the modulated and integrated detected signals to generate two components of the two-dimensional detected vector.

In the capacitive touch sensing device of the embodiment of the invention, when an object is close to the sensing unit, the vector norm may become larger or smaller. Therefore, by comparing the vector norm with a threshold value, it can be determined whether the object exists in the vicinity of the sensing unit, and since the vector norm is only a scalar quantity, the phase shift of the signal line in the sensing array can be excluded ( The effect of phase shift is to increase the accuracy of the judgment.

The above and other objects, features, and advantages of the present invention will become more apparent from the accompanying drawings. In the description of the present invention, the same components are the same The number indicates that this is a combination of the first.

Please refer to FIG. 2 , which shows a schematic diagram of a capacitive touch sensing device according to an embodiment of the invention. The capacitive touch sensing device of the present embodiment includes a sensing unit 10, a driving unit 12, a detecting circuit 13, and a processing unit 14. The capacitive touch sensing device detects whether an object (such as, but not limited to, a finger or a metal piece) is close to the sensing unit 10 by determining a change in the charge of the sensing unit 10.

The sensing unit 10 includes a first electrode 101 (eg, a driving electrode) and a second electrode 102 (eg, a receiving electrode). When a voltage signal is input to the first electrode 101, the first electrode 101 and the second electrode An electric field is generated between the electrodes 102 and a coupling capacitor 103 is formed. The first electrode 101 and the second electrode 102 can be appropriately disposed without particular limitation, as long as the coupling capacitor 103 can be formed (for example, through a dielectric layer); wherein the first electrode 101 and the second electrode The principle of generating an electric field and a coupling capacitor 103 in 102 is well known and will not be described here. The spirit of the present invention is to eliminate the influence of the phase difference caused by the capacitance on the signal line on the detection result.

The driving unit 12 is, for example, a signal generating unit that can emit a driving signal x(t) to the first electrode 101 of the sensing unit 10. The drive signal x(t) can be a time varying signal, such as a periodic signal. In other embodiments, the driving signal x(t) may also be a pulse signal, such as a square wave, a triangular wave, etc., but is not limited thereto. The The driving signal x(t) can couple a detecting signal y(t) to the second electrode 102 of the sensing unit 10 through the coupling capacitor 103.

The detection circuit 13 is coupled to the second electrode 102 of the sensing unit 10 for detecting the detection signal y(t), and modulating the detection signal y(t) by using two signals respectively to generate a pair of adjustments. The post-detection signal is used as two components I, Q of a two-dimensional detection vector; wherein the two signals can be continuous signals, such as continuous signals or two vectors that are orthogonal or non-orthogonal to each other. In one embodiment, the two signals are a sinusoidal signal and a cosine signal; wherein the phase difference between the sinusoidal signal and the cosine signal may be zero or non-zero.

The processing unit 14 is configured to calculate a scale of the pair of modulated detection signals as a norm of vector of the two-dimensional detection vector (I, Q), and compare the vector norm with A threshold TH is used to determine a touch event. In an embodiment, the processing unit 14 can calculate the vector norm by means of software. In another embodiment, the processing unit 14 can also perform calculation by using a hardware or a firmware, for example, using a coordinate rotation digital computer (CORDIC) shown in FIG. number Among them, CORDIC is a well-known fast algorithm. For example, when no object is close to the sensing unit 10, it is assumed that the vector norm calculated by the processing unit 14 is R; when an object approaches the sensing unit 10, the vector norm is reduced to R ' ; When the vector norm R ' is less than the threshold TH, the processing unit 14 can determine that an object is located near the sensing unit 10 and cause a touch event. It should be noted that when other objects, such as metal pieces, approach the sensing unit 10, it is also possible to cause the vector norm R to increase, so the processing unit 14 can also change the vector norm to be greater than a predetermined threshold. The value is determined to be a touch event.

In another embodiment, the processing unit 14 may encode the two components I and Q of the two-dimensional detection vector by Quadrature Amplitude Shift Keying (QASK), such as 16-QASK. In the processing unit 14, a part of the codes in the QASK encoding is correspondingly touched as a touch event and the other part of the code is correspondingly touched. When the processing unit 14 calculates the QASK code of the current two components I and Q according to the post-modulation detection signal, it can be determined whether an object is close to the sensing unit 10.

3A and 3B show another schematic diagram of a capacitive touch sensing device according to an embodiment of the present invention, which shows an embodiment of the detecting circuit 13.

In FIG. 3A, the detection circuit 13 includes two multipliers 131 and 131 ' , two integrators 132 and 132 ' , and two analog-to-digital conversion units (ADCs) 133 and 133 ' for processing the detection signal y(t). To generate a two-dimensional detection vector (I, Q). The two multipliers 131 and 131 ' are used to respectively display two signals, for example, as as well as Modulating with the detection signal y(t) to generate a pair of modulated detection signals y ₁ (t) and y ₂ (t). In order to sample the pair of modulated detection signals y ₁ (t) and y ₂ (t), the pair of integrator detection signals y ₁ (t) and y ₂ (t) are performed by the two integrators 132 and 132 ' In the embodiment, the form of the two integrators 132 and 132 ' is not particularly limited, and may be, for example, a capacitor. The two types of digital-to-digital conversion units 133 and 133 ' are used to digitize the integrated pairs of modulated detection signals y ₁ (t) and y ₂ (t) to generate two-digit components I of the two-dimensional detection vector, Q. It can be understood that the two analog-bit converting units 133 and 133 ' start to extract digital data when the potential changes of the two integrators 132 and 132 ' are stable. The two signals may be two vectors in addition to the two consecutive signals described above, for example, S ₁ =[1 0 -1 0] and S ₂ =[0 -1 0 1] to simplify the circuit architecture. The two signals are not limited as long as they are suitable simplification vectors capable of simplifying the modulation and demodulation process.

In FIG. 3B, the detection circuit 13 includes a multiplier 131, an integrator 132, and an analog-to-digital conversion unit 133, and the two signals S ₁ and S ₂ are input to the multiplier 131 via a multiplexer 130 to The detection signal y(t) is modulated to generate two modulated detection signals y ₁ (t) and y ₂ (t). In addition, the functions of the multiplier 131, the integrator 132, and the analog-digital conversion unit 133 are the same as those in FIG. 3A, and thus will not be described again.

In summary, the method for detecting a capacitive touch sensing device according to the embodiment of the present invention includes the steps of: inputting a driving signal to a first electrode of a sensing unit; and separately modulating the driving signal by two signals The signal is coupled to a detection signal of a second electrode through a coupling capacitor to generate a pair of modulated detection signals; and the magnitude of the detected signal after the modulation is determined and a touch event is determined accordingly.

For example, as shown in FIG. 3A and FIG. 3B, after the driving unit 12 inputs a driving signal x(t) to the first electrode 101 of the sensing unit 10, the driving signal x(t) is coupled through the coupling capacitor 103 to detect Signal y(t) to the second electrode 102 of the sensing unit 10. Then, the detecting circuit 13 modulates the detection signal y(t) with the two signals S ₁ and S ₂ respectively to generate a pair of modulated detection signals y ₁ (t) and y ₂ (t). The processing unit 14 calculates the magnitude of the pair of modulated detection signals y ₁ (t) and y ₂ (t) and determines a touch event; wherein the pair of modulated detection signals y ₁ (t) and For the manner of the size of y ₂ (t), for example, reference can be made to FIG. 4 and its related description. In addition, before calculating the magnitude of the pair of modulated detection signals y ₁ (t) and y ₂ (t), the integrator 132 and/or 132 ' can be used to integrate the pair of modulated detection signals y ₁ (t) And after y ₂ (t), the analog-to-digital conversion unit 133 and/or 133 ' performs digitization to output the two-digit components I and Q of the two-dimensional detection vector (I, Q).

Please refer to FIG. 5 , which shows a schematic diagram of a capacitive touch sensing device according to another embodiment of the present invention. The array of the plurality of sensing units 10 can form a capacitive sensing array. Each of the sensing units 10 is driven by a driving unit 12 ₁ 12 12 _n and the detecting circuit 13 detects each through the plurality of switching elements SW ₁ SW SW _{m .} One line of the output signal of the sensing unit 10. As shown in FIG. 5, the driving unit 12 _{1 is} used to drive the first column sensing unit 10 ₁₁ ~ 10 _1m ; the driving unit 12 _{2 is} used to drive the second column sensing unit 10 ₂₁ ~ 10 _2m : ...; the driving unit 12 _n For driving the nth column sensing unit 10 _n1 ~ 10 _nm ; wherein n and m are positive integers and the value thereof can be determined according to the size and resolution of the capacitance sensing array, and there is no particular limitation.

In this embodiment, each sensing unit 10 (shown here as a circle) includes a first electrode and a second electrode for forming a coupling capacitor, as shown in FIGS. 2, 3A and 3B. The driving units 12 ₁ - 12 _n are respectively coupled to the first electrodes of the column of sensing units 10 . A timing controller 11 is configured to control the driving units 12 ₁ to 12 _{n to} sequentially output a driving signal x(t) to the first electrodes of the sensing units 10 .

The detecting circuit 13 is coupled to the second electrode of the sensing unit 10 through the plurality of switching elements SW ₁ to SW _{m for} sequentially detecting the coupling capacitance of the driving signal x(t) through the sensing units 10 . The detection signal y(t) is coupled to one of the second electrodes, and the detection signal y(t) is separately modulated by the two signals to generate a pair of modulated detection signals; wherein the pair of modulated detections are generated The manner of the signal has been described in detail in FIGS. 3A and 3B and related descriptions, and thus will not be described herein.

The processing unit 14 determines a touch event and a touch position according to the pair of modulated detection signals. As described above, the processing unit 14 may calculate a vector norm of a two-dimensional detection vector formed by the pair of modulated detection signals, and determine the vector norm when the vector norm is less than or equal to or greater than or equal to a threshold TH. Touch the event, as shown in Figure 4.

In this embodiment, when the timing controller 11 controls the driving unit 12 _{1 to} output the driving signal x(t) to the first column sensing unit 10 ₁₁ ~ 10 _1m , the switching elements SW ₁ ~ SW _m are The sequence is turned on to enable the detection circuit 13 to sequentially detect the detection signal y(t) output by each of the sensing units of the first column of sensing units 10 ₁₁ to 10 _{1 m} . Then, the timing controller 11 sequentially controls the other driving units 12 ₂ to 12 _{N to} output the driving signal x(t) to each column sensing unit. After the detecting circuit 13 detects all the sensing units, a scan period is completed. The processing unit 14 determines the position of the sensing unit in which the touch event occurs in one scan period as the touch position. It can be understood that the touch position may not only occur in one sensing unit 10, but the processing unit 14 may regard the position of the plurality of sensing units 10 as a touch position, or one of the plurality of sensing units 10. The position (for example, center or center of gravity) is treated as a touch position.

Referring to FIG. 6 , a flow chart of the operation of the capacitive touch sensing device according to the embodiment of the present invention includes the following steps: inputting a driving signal to one sensing unit of a capacitive sensing array (step S ₃₁ ); The two signals are respectively modulated to detect one of the detection signals of the sensing unit to generate a pair of modulated detection signals (step _S32 ); integrating and digitizing the pair of modulated detection signals (step _S33 ); and determining A touch event and a touch position (step _S34 ). The operation mode of this embodiment has been described in detail in FIG. 5 and its related description, and thus will not be further described herein.

In another embodiment, in order to save the energy consumption of the capacitive touch sensing device in FIG. 5, the timing controller 11 can control the plurality of driving units 12 ₁ to 12 _{n to} simultaneously output the driving signal x(t) to the corresponding column. Sensing unit. The detection circuit 13 modulates each column of detection signals y(t) with different two consecutive signals S ₁ , S ₂ to distinguish them. In addition, the manner of judging the touch event and the touch position is similar to that of FIG. 5, and thus will not be described again.

In the embodiment of the present invention, the detecting circuit 13 may further comprise components such as filters and/or amplifiers to increase signal quality. In addition, the processing unit 14 can also be combined with the detection circuit 13 into a single component.

In summary, the conventional active capacitive touch sensor must be calibrated for different touch panels to correctly detect the voltage signal, thus having a high production complexity. The invention further provides a capacitive touch sensing device (Figs. 2, 3A and 3B) and a detecting method thereof (Fig. 6), which use two continuous signals to respectively modulate the detecting signal and detect the signal according to the modulated signal. The vector norm determines the touch event (Fig. 4) to eliminate the effects of the phase difference caused by the sensing array signal lines and to simplify the process.

The present invention has been disclosed in the foregoing embodiments, and is not intended to limit the present invention. Any of the ordinary skill in the art to which the invention pertains can be modified and modified without departing from the spirit and scope of the invention. . Therefore, the scope of the invention is defined by the scope of the appended claims.

10‧‧‧Sensor unit

101, 91‧‧‧ first electrode

102, 92‧‧‧ second electrode

103‧‧‧Coupling capacitor

11‧‧‧Timing controller

12, 12 ₁ ~ 12 _n ‧‧‧ drive unit

13, 94‧‧‧Detection circuit

131, 131 ' ‧‧‧ Multiplier

132,132 ' ‧‧‧ integrator

133, 133 ' ‧‧‧ analog digital conversion unit

14‧‧‧Processing unit

93‧‧‧Drive Circuit

941‧‧‧Detection switch

942‧‧‧Detection unit

8‧‧‧ fingers

x(t)‧‧‧ drive signal

y(t)‧‧‧Detection signal

y ₁ (t), y ₂ (t) ‧‧ ‧ detection signal after modulation

SW ₁ ~SW _m ‧‧‧Switching elements

S ₁ , S ₂ ‧‧‧ continuous signal

S ₃₁ ~S ₃₄ ‧‧‧Steps

I, Q‧‧‧ The component of the detection vector

1A-1C are block diagrams showing a conventional active capacitive touch sensor.

FIG. 2 is a schematic diagram of a capacitive touch sensing device according to an embodiment of the invention.

3A-3B show another schematic diagram of a capacitive touch sensing device according to an embodiment of the invention.

FIG. 4 is a schematic diagram showing a vector norm and a threshold value in a capacitive touch sensing device according to an embodiment of the invention.

FIG. 5 is a schematic diagram of a capacitive touch sensing device according to another embodiment of the present invention.

FIG. 6 is a flow chart showing the operation of the capacitive touch sensing device of FIG. 5.

10‧‧‧Sensor unit

101‧‧‧First electrode

102‧‧‧second electrode

103‧‧‧Coupling capacitor

12‧‧‧Drive unit

13‧‧‧Detection circuit

14‧‧‧Processing unit

Claims (20)

A capacitive touch sensing device includes: a first electrode and a second electrode for forming a coupling capacitor; a driving unit for emitting a driving signal to the first electrode; and a detecting circuit coupled The second electrode is configured to detect that the driving signal is coupled to the detection signal of the second electrode through the coupling capacitor, and the two signals are respectively used to modulate the detection signal to generate a two-dimensional detection vector; and The processing unit is configured to calculate a vector norm of the two-dimensional detection vector and compare the vector norm with a threshold to determine a touch event. The capacitive touch sensing device of claim 1, wherein the two signals are continuous signals that are orthogonal to each other. According to the capacitive touch sensing device of claim 1, wherein the two signals are a sinusoidal signal and a cosine signal. The capacitive touch sensing device of claim 1, wherein the processing unit calculates the vector norm by using a coordinate rotation digital computer. The capacitive touch sensing device of claim 1, wherein the driving signal is a periodic signal. The capacitive touch sensing device of claim 1, wherein the detecting circuit further comprises at least one integrator and at least one analog converting unit, wherein the integrator is used to integrate the modulated detecting signal; The analog digital conversion unit is configured to digitize the modulated and integrated detected signals to generate two components of the two-dimensional detected vector. A method for detecting a capacitive touch sensing device, the capacitive touch sensing device comprising a sensing unit comprising a first electrode and a second electrode for forming a coupling capacitor, the detecting method comprising Transducing a driving signal to the first electrode of the sensing unit; respectively, the two signals are respectively modulated by the coupling signal to be coupled to the detection signal of the second electrode to generate a pair of modulated detection signals; And calculating the magnitude of the pair of modulated detection signals and determining a touch event. The method for detecting the seventh aspect of the patent application, wherein the size of the pair of modulated detection signals is a vector norm of a two-dimensional vector formed by the pair of modulated detection signals. The detection method according to item 8 of the patent application scope, wherein the vector norm is obtained by using a coordinate rotation digital computer. According to the detection method of claim 7, wherein the two signals are a sinusoidal signal and a cosine signal. According to the detection method of claim 7, wherein the two signals are continuous signals orthogonal to each other. According to the detecting method of the seventh aspect of the patent application, wherein the driving signal is a one-cycle signal. According to the detecting method of the seventh aspect of the patent application, wherein calculating the size of the detected signal after the modulation, the method further comprises: integrating and digitizing the pair of modulated signals after the modulation. A capacitive touch sensing device comprising: a capacitive sensing array comprising a plurality of sensing units arranged in an array, each sensing unit comprising a first electrode and a second electrode for forming a coupling capacitor; a plurality of driving units coupled to the sensing unit An electrode for sequentially outputting a driving signal to the first electrode; a detecting circuit coupled to the second electrode of the sensing unit for sequentially detecting that the driving signal is coupled to the driving capacitor through the coupling capacitor One of the second electrodes detects a signal, and the two signals respectively modulate the detection signal to generate a pair of modulated detection signals; and a processing unit determines a touch event and a touch according to the modulated signal after the modulation Touch the position. The capacitive touch sensing device of claim 14, wherein the two signals are continuous signals that are orthogonal to each other. According to the capacitive touch sensing device of claim 14, wherein the two signals are a sinusoidal signal and a cosine signal. The capacitive touch sensing device of claim 14, wherein the driving signal is a periodic signal. According to the capacitive touch sensing device of claim 14, wherein the processing unit calculates a vector norm of a two-dimensional detection vector formed by the pair of modulated detection signals, when the vector norm is less than or It is determined that the touch event occurs when it is greater than a threshold. The capacitive touch sensing device according to claim 18, wherein the processing unit calculates the vector norm by using a coordinate rotation digital computer. The capacitive touch sensing device of claim 14, wherein the processing unit determines the position of the at least one of the sensing units in the scan period to be the touch position.