TWI759017B - Noise detection method and touch chip and touch display using the same - Google Patents

Abstract

A noise detection method for judging whether a touch scanning frequency has noise, comprising: making a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency, so as to perform a plurality of stage sensing operations at each touch scanning frequency. A plurality of sensing values are obtained in the staged sensing operation, wherein any subsequent staged sensing operation is behind a previous staged sensing operation by a predetermined time; and a The control unit performs an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performs a judgment procedure on the plurality of average values, which includes: according to each The difference between the average value and a corresponding preset value generates a difference value, and it is judged whether the larger one of the plurality of the difference values is greater than a threshold value, and if so, it is judged that the touch scanning frequency is a noise-bearing frequency. a scan frequency.

Description

Noise detection method and touch chip and touch display using the same

The present invention relates to a noise detection method, in particular to a noise detection method for touch sensing.

With the increasing popularity and vigorous development of mobile devices, the human-machine interface of the display screen has become more and more intelligent, and can provide more and more functions, including input operation functions such as touch and pressure sensing, as well as fingerprint recognition, audio Biometric recognition functions such as pattern recognition and iris recognition.

However, since there are interference sources in mobile devices, such as charger noise, fluorescent lamp radiation noise, mobile phone radiation noise and other interference sources, when the frequency of the interference source is close to the sensing scanning frequency, the sensing function is possible. It will fail and make users feel unpleasant operating experience.

To solve the above problems, a novel noise detection method is urgently needed in the art so that the sensing scanning frequency avoids the frequency of the interference source.

An object of the present invention is to disclose a noise detection method, which can perform a plurality of staged sensing operations, wherein each subsequent staged sensing operation is delayed relative to a preceding staged sensing operation by a Predetermined time, and increase the detection ability of noise frequency points.

Another object of the present invention is to disclose a noise detection method, which can effectively detect a noise frequency point through a plurality of stages of sensing operations, and switch to a clean frequency point in time after detecting the noise frequency point, In order to avoid false alarms of touch points, so as to improve the user experience.

In order to achieve the aforementioned purpose, a noise detection method is proposed to determine whether a touch scan frequency has noise, which includes:

Make a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency to obtain a plurality of sensing values in each of the staged sensing operations, wherein any one of the following The staged sensing operations are all behind a preceding staged sensing operation by a predetermined time; and

A control unit performs an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performs a judgment procedure on the plurality of average values, including: generating a difference value according to the difference between each of the average values and a corresponding preset value, and determining whether the larger one of the plurality of the difference values is greater than a threshold value; One of the scan frequencies of the message.

In one embodiment, the sensing circuit has:

an amplifier having a positive input terminal, a negative input terminal and an output terminal, the positive input terminal is coupled to a common mode voltage;

A sensing capacitor is coupled between a touch sensing point and a reference ground. The touch sensing point is used to sense the signal charge injected by a touch operation, and in the presence of noise the noise will introduce noise charges into the touch sensing point;

a first switch, having a control terminal and a channel, the control terminal is coupled to a first switch signal, the channel is coupled between the touch sensing point and the negative input terminal; and

A feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, the control terminal is coupled to a second switch signal, the channel is connected in parallel with the feedback capacitor, and The feedback circuit is coupled between the negative input terminal and the output terminal.

In one embodiment, the sensing circuit performs the staged sensing operation according to the control of an operation timing of the first switching signal and the second switching signal.

In order to achieve the aforementioned object, the present invention further provides a touch chip, which is used for executing a noise detection method to determine whether a touch scan frequency has noise, and the method includes:

Make a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency to obtain a plurality of sensing values in each of the staged sensing operations, wherein any one of the following The staged sensing operations are all behind a preceding staged sensing operation by a predetermined time; and

A control unit performs an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performs a judgment procedure on the plurality of average values, including: generating a difference value according to the difference between each of the average values and a corresponding preset value, and determining whether the larger one of the plurality of the difference values is greater than a threshold value; One of the scan frequencies of the message.

In one embodiment, the sensing circuit has:

an amplifier having a positive input terminal, a negative input terminal and an output terminal, the positive input terminal is coupled to a common mode voltage;

A sensing capacitor is coupled between a touch sensing point and a reference ground. The touch sensing point is used to sense the signal charge injected by a touch operation, and in the presence of noise the noise will introduce noise charges into the touch sensing point;

a first switch, having a control terminal and a channel, the control terminal is coupled to a first switch signal, the channel is coupled between the touch sensing point and the negative input terminal; and

A feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, the control terminal is coupled to a second switch signal, the channel is connected in parallel with the feedback capacitor, and The feedback circuit is coupled between the negative input terminal and the output terminal.

In one embodiment, the sensing circuit performs the staged sensing operation according to the control of an operation timing of the first switching signal and the second switching signal.

In a possible embodiment, the control unit is located inside the touch chip or is an application processor.

In order to achieve the aforementioned object, the present invention further provides a touch display having a touch screen and a touch chip for driving the touch screen, and the touch chip is used for executing a noise detection method to determine a Whether the touch scan frequency has noise, the method includes:

Make a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency to obtain a plurality of sensing values in each of the staged sensing operations, wherein any one of the following The staged sensing operations are all behind a preceding staged sensing operation by a predetermined time; and

A control unit performs an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performs a judgment procedure on the plurality of average values, including: generating a difference value according to the difference between each of the average values and a corresponding preset value, and determining whether the larger one of the plurality of the difference values is greater than a threshold value; One of the scan frequencies of the message.

In one embodiment, the sensing circuit has:

an amplifier having a positive input terminal, a negative input terminal and an output terminal, the positive input terminal is coupled to a common mode voltage;

A sensing capacitor is coupled between a touch sensing point and a reference ground. The touch sensing point is used to sense the signal charge injected by a touch operation, and in the presence of noise the noise will introduce noise charges into the touch sensing point;

a first switch, having a control terminal and a channel, the control terminal is coupled to a first switch signal, the channel is coupled between the touch sensing point and the negative input terminal; and

A feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, the control terminal is coupled to a second switch signal, the channel is connected in parallel with the feedback capacitor, and The feedback circuit is coupled between the negative input terminal and the output terminal.

In one embodiment, the sensing circuit performs the staged sensing operation according to the control of an operation sequence of the first switch signal and the second switch signal, and the control unit is located inside the touch chip Or an application processor.

In order to enable your examiners to further understand the structure, features and purposes of the present invention, the accompanying drawings and detailed descriptions of preferred embodiments are as follows.

Please refer to FIG. 1 and FIG. 2 together, wherein FIG. 1 shows a flowchart of an embodiment of a noise detection method of the present invention, which is used to determine whether a touch scan frequency has noise; and FIG. 2 A block diagram of one embodiment of the sensing circuit of FIG. 1 is shown.

As shown in FIG. 1 , the noise detection method includes the following steps: causing a sensing circuit to perform a first-stage sensing operation according to the touch scanning frequency to obtain a plurality of first sensing values, and using a control unit Perform an average calculation on the plurality of first sensing values to generate a first average value (step a); make the sensing circuit perform a second-stage sensing according to the touch scanning frequency after a predetermined time delay operate to obtain a plurality of second sensing values, and use the control unit to perform an average calculation on the plurality of second sensing values to generate a second average value (step b); and use the control unit to perform an average calculation on the first A judgment process is performed on an average value and the second average value, which includes: generating a first difference value according to the difference between the first average value and a first predetermined value, and according to the second average value and a second predetermined value The difference between the set values generates a second difference, and it is judged whether the larger of the first difference and the second difference is greater than a threshold, and if so, it is judged that the touch scan frequency is a scan with noise frequency (step c). In addition, in the noise detection method, the control unit may be an application processor or located in a touch chip.

As shown in FIG. 2 , a sensing circuit 100 includes an amplifier 110 , a sensing capacitor 120 , a first switch 130 and a feedback circuit 140 .

The amplifier 110 has a positive input terminal (+), a negative input terminal (-) and an output terminal, the positive input terminal is coupled to a common mode voltage V _CM , and the output terminal is used to generate an output voltage V _OUT .

The sensing capacitor 120 is coupled between a touch sensing point A and a reference ground GND. The touch sensing point A is used for sensing a signal charge injected by a touch operation, and when there is noise In this case, the noise will introduce noise charges into the touch sensing point A.

The first switch 130 has a control terminal and a channel, the control terminal is coupled to a first switch signal S1, and the channel is coupled between the touch sensing point A and the negative input terminal (-).

The feedback circuit 140 is composed of a second switch 141 and a feedback capacitor 142 . The second switch 141 has a control terminal and a channel. The control terminal is coupled to a second switch signal S2 , and the channel is connected to the feedback capacitor 142 . In parallel, the feedback circuit 140 is coupled between the negative input terminal (-) and the output terminal (+).

The sensing circuit 100 performs the first-stage sensing operation and the second-stage sensing operation according to the control of an operation timing of the first switching signal S1 and the second switching signal S2.

The working principle of the sensing operation is as follows:

In the first phase, the first switch signal S1 and the second switch signal S2 are both at high potential, the amplifier 110 forms a unity gain buffer, and resets the sensing capacitor 120 and the feedback capacitor 142;

In the second phase, the first switch signal S1 is at a high level, the second switch signal S2 is at a low level, and the sensing capacitor 120 is connected to the negative input terminal (-) of the amplifier 110 at the same time. At this time, the amplifier 110 forms a A charge amplifier is output to an analog digital converter (not shown in the figure) through the output voltage V _OUT . If noise occurs at this time, the noise will be contributed to the output voltage V through the feedback capacitor 142 at the same time. _OUT .

The following is an experimental result of the present invention:

In an experiment, a square wave noise with a pulse height of 3.5V and a frequency of 100K was applied, the detection frequency was 100K, and the delay time between the first-stage sensing operation and the second-stage sensing operation was 2.5 microseconds (µs). And the threshold is set to 0.2V, and the obtained experimental data are shown in Table 1. Table 1. Noise occurrence time (µs) real scanning environment Noise-free scanning environment The first difference (V) Second Difference (V) MAX (first difference, second difference)>threshold (0.2V)? First average (V) Second average (V) The first preset value (V) Second preset value (V) 0 2.895 2.565 2.565 2.565 0.33 0 Yes 0.5 2.893 2.779 2.565 2.565 0.328 0.214 Yes 1 2.893 2.895 2.565 2.565 0.328 0.33 Yes 1.5 2.894 2.895 2.565 2.565 0.329 0.33 Yes 2 2.656 2.895 2.565 2.565 0.091 0.33 Yes 2.5 2.565 2.895 2.565 2.565 0 0.33 Yes 3 2.291 2.895 2.565 2.565 0.274 0.33 Yes 3.5 2.235 2.895 2.565 2.565 0.33 0.33 Yes 4 2.234 2.893 2.565 2.565 0.331 0.328 Yes 4.5 2.235 2.656 2.565 2.565 0.33 0.091 Yes 5 2.235 2.565 2.565 2.565 0.33 0 Yes 5.5 2.235 2.291 2.565 2.565 0.33 0.274 Yes 6 2.235 2.235 2.565 2.565 0.33 0.33 Yes 6.5 2.235 2.235 2.565 2.565 0.33 0.33 Yes 7 2.511 2.235 2.565 2.565 0.054 0.33 Yes 7.5 2.565 2.235 2.565 2.565 0 0.33 Yes 8 2.779 2.235 2.565 2.565 0.214 0.33 Yes 8.5 2.895 2.235 2.565 2.565 0.33 0.33 Yes 9 2.895 2.235 2.565 2.565 0.33 0.33 Yes 9.5 2.895 2.511 2.565 2.565 0.33 0.054 Yes

It can be known from Table 1 that in the case of different noise occurrence time points, the present invention can detect the noise by using the larger of the first difference value and the second difference value.

According to the above description, the noise detection method of the present invention can be further extended as follows:

Make a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency to obtain a plurality of sensing values in each of the staged sensing operations, wherein any one of the following The staged sensing operations are all behind a preceding staged sensing operation by a predetermined time; and

A control unit performs an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performs a judgment procedure on the plurality of average values, including: generating a difference value according to the difference between each of the average values and a corresponding preset value, and determining whether the larger one of the plurality of the difference values is greater than a threshold value; One of the scan frequencies of the message.

In addition, according to the above description, the present invention further discloses a touch chip and a touch display.

Please refer to FIG. 3 , which shows a block diagram of an embodiment of the touch chip of the present invention. As shown in FIG. 3 , a touch chip 200 has a micro-processing unit 210 and a touch driving circuit 220 to perform the aforementioned noise detection method, wherein the touch driving circuit 220 has at least one sensing circuit 100 and performs the above-mentioned noise detection method. The control unit for judging the program can be an external processor (not shown in the figure) or the microprocessor unit 210 .

Please refer to FIG. 4 , which shows a block diagram of an embodiment of the touch display of the present invention. As shown in FIG. 4 , a touch display 300 has a touch chip 310 and a touch screen 320 , wherein the touch chip 310 is realized by the touch chip 200 , and the control unit that executes the judgment procedure can be an application A processor (not shown in the figure, for example located in an information processing device of a smart phone) or the microprocessor unit 210 .

By the design disclosed above, the present invention has the following advantages:

1. The noise detection method of the present invention uses a two-stage sensing operation, and controls the delay time between the first-stage sensing operation and the second-stage sensing operation, so that the noise does not fall into the The reset phase between the first-stage sensing operation and the second-stage sensing operation.

2. In the noise detection method of the present invention, through the two-stage sensing operation, even if the noise happens to appear in the reset phase, the noise detection data of the current frequency point can still be obtained, so that the microcontroller can switch to the current frequency in time. Clean frequency points, there will be no false alarms of touch points, thereby improving user experience.

What is disclosed in the present invention is the preferred embodiment, and any partial changes or modifications that are derived from the technical idea of the present invention and can be easily inferred by those skilled in the art do not depart from the scope of the patent right of the present invention.

To sum up, regardless of the purpose, means and effect of the present invention, it shows that it is completely different from the prior art, and its first invention is suitable for practical use, and indeed meets the patent requirements of the invention. To benefit the society is to pray for the best.

100: Sensing circuit 110: Amplifier 120: Sensing Capacitance 130: The first switch 140: Feedback circuit 141: Second switch 142: feedback capacitor 200: Touch Chip 210: Microprocessing unit 220: touch drive circuit 300: Touch Monitor 310: Touch Chip 320: touch screen Step a: make a sensing circuit perform a first-stage sensing operation according to the touch scanning frequency to obtain a plurality of first sensing values, and use a control unit to perform an average on the plurality of first sensing values calculated to produce a first average Step b: Make the sensing circuit perform a second-stage sensing operation according to the touch scanning frequency after a delay of a predetermined time to obtain a plurality of second sensing values, and use the control unit to perform a second-stage sensing operation on the plurality of second sensing values. Sensing values are averaged to generate a second average Step c: use the control unit to perform a judgment procedure on the first average value and the second average value, which includes: generating a first difference value according to the difference between the first average value and a first preset value, The difference between the second average value and a second predetermined value generates a second difference value, and it is judged whether the larger of the first difference value and the second difference value is greater than a threshold value, and if so, judge the touch The control scan frequency is one of the scan frequencies with noise

FIG. 1 is a flowchart illustrating an embodiment of the noise detection method of the present invention. FIG. 2 is a block diagram illustrating one embodiment of the sensing circuit of FIG. 1 . FIG. 3 is a block diagram illustrating an embodiment of the touch chip of the present invention. FIG. 4 is a block diagram illustrating an embodiment of the touch display of the present invention.

Step a: make a sensing circuit perform a first-stage sensing operation according to the touch scanning frequency to obtain a plurality of first sensing values, and use a control unit to perform an average on the plurality of first sensing values calculated to produce a first average

Step b: Make the sensing circuit perform a second-stage sensing operation according to the touch scanning frequency after a delay of a predetermined time to obtain a plurality of second sensing values, and use the control unit to perform a second-stage sensing operation on the plurality of second sensing values. Sensing values are averaged to generate a second average

Step c: use the control unit to perform a judgment procedure on the first average value and the second average value, which includes: generating a first difference value according to the difference between the first average value and a first preset value, The difference between the second average value and a second predetermined value generates a second difference value, and it is judged whether the larger of the first difference value and the second difference value is greater than a threshold value, and if so, judge the touch The control scan frequency is one of the scan frequencies with noise

Claims (10)

A noise detection method for judging whether a touch scanning frequency has noise, comprising: making a sensing circuit perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency, so as to perform a plurality of stage sensing operations at each touch scanning frequency. A plurality of sensing values are obtained in the staged sensing operations, wherein the latter of any two adjacent ones of the staged sensing operations is behind the predecessor by a predetermined time; and a control unit is made to Performing an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and performing a judging process on the plurality of average values, including: according to each of the average values The difference between the value and a corresponding preset value generates a difference value, and it is judged whether the larger of the plurality of said difference values is greater than a threshold value, and if so, it is judged that the touch scanning frequency is a scanning frequency with noise . The noise detection method as described in claim 1, wherein the sensing circuit has: an amplifier having a positive input terminal, a negative input terminal and an output terminal, the positive input terminal is coupled to a common mode voltage connected; a sensing capacitor, coupled between a touch sensing point and a reference ground, the touch sensing point is used for sensing a signal charge injected by a touch operation, and in the presence of noise Under the circumstance, the noise will introduce noise charge into the touch sensing point; a first switch has a control terminal and a channel, the control terminal is coupled to a first switch signal, and the channel is coupled to the touch between the sensing point and the negative input terminal; and a feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, the control terminal is coupled to a second switch signal, the channel is connected in parallel with the feedback capacitor, and the feedback circuit is coupled between the negative input terminal and the output terminal. The noise detection method as described in claim 2, wherein the sensing circuit performs the staged sensing operation according to the control of an operation timing of the first switch signal and the second switch signal. A touch chip is used for executing a noise detection method to determine whether a touch scan frequency has noise. The method includes: making a sensing circuit perform a plurality of stages on a sensing point according to the touch scan frequency A multi-stage sensing operation is used to obtain a plurality of sensing values in each of the staged sensing operations, wherein the latter of any two adjacent ones of the staged sensing operations is behind the former by a predetermined time. ; and make a control unit perform an average calculation on the plurality of sensing values obtained in each of the staged sensing operations to obtain an average value, and perform a judgment procedure on the plurality of the average values, which Including: generating a difference value according to the difference between each of the average values and a corresponding preset value, and judging whether the larger one of the plurality of the difference values is greater than a threshold, and if so, judging that the touch scanning frequency is One of the sweep frequencies with noise. The touch chip as described in claim 4, wherein the sensing circuit has: an amplifier having a positive input terminal, a negative input terminal and an output terminal, and the positive input terminal is coupled to a common mode voltage ; a sensing capacitor, coupled between a touch sensing point and a reference ground, the touch sensing point is used to sense a signal charge injected by a touch operation, and in the presence of noise Under the noise, the noise charge will be introduced into the touch sensing point; a first switch has a control terminal and a channel, the control terminal is coupled to a first switch signal, and the channel is coupled to the touch sensing point between the measuring point and the negative input terminal; and a feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, and the control terminal is coupled to a second switch signal , the channel is connected in parallel with the feedback capacitor, and the feedback circuit is coupled between the negative input end and the output end. The touch control chip as claimed in claim 5, wherein the sensing circuit performs the staged sensing operation according to the control of an operation sequence of the first switch signal and the second switch signal. The touch chip as described in claim 4, wherein the control unit is located inside the touch chip or is an external processor. A touch display has a touch screen and a touch chip for driving the touch screen, the touch chip is used for executing a noise detection method to determine whether a touch scanning frequency has noise , the method includes: causing a sensing circuit to perform a plurality of staged sensing operations on a sensing point according to the touch scanning frequency to obtain a plurality of sensing values in each of the staged sensing operations, wherein, In any two adjacent ones of the staged sensing operations, the latter is behind the predecessor by a predetermined time; and a control unit is made to measure the plurality of sensing values obtained in each of the staged sensing operations An average calculation is performed to obtain an average value, and a judgment procedure is performed on a plurality of the average values, which includes: generating a difference value according to the difference between each of the average values and a corresponding preset value, and judging the plurality of average values. Whether the larger of the difference values is greater than a threshold, and if so, it is determined that the touch scan frequency is a scan frequency with noise. The touch display as described in claim 8, wherein the sensing circuit has: an amplifier having a positive input terminal, a negative input terminal and an output terminal, the positive input terminal is coupled to a common mode voltage ; a sensing capacitor, coupled between a touch sensing point and a reference ground, the touch sensing point is used to sense a signal charge injected by a touch operation, and in the presence of noise Under the noise, the noise charge will be introduced into the touch sensing point; a first switch has a control terminal and a channel, the control terminal is coupled to a first switch signal, and the channel is coupled to the touch sensing point between the measuring point and the negative input terminal; and a feedback circuit composed of a second switch and a feedback capacitor, the second switch has a control terminal and a channel, and the control terminal is coupled to a second switch signal , the channel is connected in parallel with the feedback capacitor, and the feedback circuit is coupled between the negative input end and the output end. The touch display as described in claim 9, wherein the sensing circuit performs the staged sensing operation according to the control of an operation sequence of the first switch signal and the second switch signal, and the The control unit is located inside the touch chip or is an application processor.

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