Capacitance Detection Method and Capacitance Detection Device

Abstract

The present application provides a capacitance detection method for a capacitance detection device. The method includes: obtaining a first capacitance measurement value in a first working mode and a second capacitance measurement value in a second working mode of a detection channel in a first environmental state; obtaining a third capacitance measurement value in the first working mode and a fourth capacitance measurement value in the second working mode of the detection channel in a second environmental state; determining a capacitance measurement change value of the capacitance between the detection channel and the drive channel and a capacitance measurement change value of the detection channel according to the differences between the obtained multiple capacitance measurement values, and determining a compensated capacitance measurement value of the detection channel. By adopting the above technical solution, the capacitance change caused by environmental changes can be corrected, thereby ensuring the capacitance detection accuracy and avoiding misjudgment. The present application also provides a capacitance detection device.

Description

Technical Field

[0001] This application relates to the field of touch detection, and particularly to a capacitance detection method and a capacitance detection device. Background Art

[0002] A capacitive sensor is a conversion device that converts a measured physical quantity or mechanical quantity into a change in capacitance. Due to its advantages such as simple structure, stable performance, and high sensitivity, capacitive sensors are widely used in the fields of industrial and consumer electronics products, such as pressure, displacement, acceleration, thickness, liquid level, etc. measurement.

[0003] The basic working principle of a capacitive sensor: Through a capacitance detection circuit, the change in the sensor capacitance can be converted into an electrical signal output. By measuring the magnitude of the electrical signal, the magnitude of the measured quantity can be judged.

[0004] In order to minimize the influence of environmental (temperature, humidity, etc.) changes on the capacitance detection value and reduce the capacitance detection accuracy, especially the misjudgment caused by environmental changes, a capacitance detection scheme that can suppress the capacitance change caused by environmental changes is needed. Summary of the Invention

[0005] Some embodiments of this application provide a capacitance detection method and a capacitance detection device. This application will be introduced from multiple aspects below, and the embodiments and beneficial effects of the following multiple aspects can be referred to each other.

[0006] In a first aspect, an embodiment of this application provides a capacitance detection method for a capacitance detection device. The method includes: obtaining a first capacitance measurement value in a first working mode and a second capacitance measurement value in a second working mode of a detection channel in a first environmental state. The first working mode includes applying a voltage signal consistent with the detection channel on a drive channel when the detection channel performs capacitance detection on a capacitance to be detected through an excitation voltage signal; the second working mode includes applying a ground voltage signal on the drive channel when the detection channel performs capacitance detection on the capacitance to be detected through the excitation voltage signal. The detection channel includes a trace for connecting the capacitance to be detected and the capacitance detection device, and one end of the drive channel is connected to the capacitance detection device and the other end is floating; obtaining a third capacitance measurement value in the first working mode and a fourth capacitance measurement value in the second working mode of the detection channel in a second environmental state, where the environmental parameters of the second environmental state are different from those of the first environmental state; determining a capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value; determining a capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value; determining a compensated capacitance measurement value of the detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel.

[0007] The capacitance detection method provided according to the first aspect of the present application can correct the capacitance change caused by environmental changes, thereby ensuring the capacitance detection accuracy and avoiding misjudgment.

[0008] In some embodiments, the capacitance between the detection channel and the drive channel includes at least one of the following: the parasitic capacitance between the detection channel and the drive channel, and the capacitance connected to the detection channel and the drive channel. The measurement value change of the capacitance existing between the detection channel and the drive channel is fully considered to improve the capacitance detection accuracy.

[0009] In some embodiments, according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value, determining the capacitance measurement change value of the capacitance between the detection channel and the drive channel includes: obtaining a first difference between the second capacitance measurement value and the first capacitance measurement value; obtaining a second difference between the fourth capacitance measurement value and the third capacitance measurement value; calculating a third difference between the first difference and the second difference; and determining the capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the third difference. Thereby, on the basis of ensuring the accuracy of the first capacitance measurement difference and the second capacitance measurement difference, the calculation speed can be improved.

[0010] In some embodiments, according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel, determining the compensated capacitance measurement value of the detection channel includes: determining a compensation coefficient according to the ratio of the capacitance measurement change value of the detection channel to the capacitance measurement change value of the capacitance between the detection channel and the drive channel; and determining the compensated capacitance measurement value of the detection channel according to the compensation coefficient. Thereby, on the basis of ensuring the accuracy of the compensation coefficient, the calculation speed can be improved.

[0011] In some embodiments, determining the compensated capacitance measurement value of the detection channel according to the compensation coefficient includes: determining the compensated capacitance measurement value of the detection channel according to the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel. By compensating the third capacitance measurement value to obtain the compensated capacitance measurement value of the detection channel, the capacitance change caused by environmental changes can be corrected, the capacitance detection accuracy can be improved, and misjudgment can be avoided.

[0012] In some embodiments, determining the capacitance measurement value of the compensated detection channel according to the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel includes: determining the capacitance measurement value of the compensated detection channel according to the difference between the third capacitance measurement value and the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel. Thereby, the capacitance change caused by environmental changes can be compensated more accurately, the capacitance detection accuracy can be improved, and misjudgment can be avoided.

[0013] In a second aspect, an embodiment of the present application provides a capacitance detection device, including: a detection capacitance sensor for obtaining a first capacitance measurement value of the detection channel in a first operating mode in a first environmental state and a third capacitance measurement value of the detection channel in a first operating mode in a second environmental state; a drive capacitance sensor for obtaining a second capacitance measurement value of the detection channel in a second operating mode in the first environmental state and a fourth capacitance measurement value of the detection channel in a second operating mode in the second environmental state; a digital processing unit for determining the capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value, determining the capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value, and determining the capacitance measurement value of the compensated detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel. It can correct the capacitance change caused by environmental changes, thereby ensuring the capacitance detection accuracy and avoiding misjudgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Shows an application scenario of a capacitance detection device provided according to some embodiments of the present application.

[0015] Figure 2 Shows a schematic structural diagram of a capacitance detection device provided according to some embodiments of the present application.

[0016] Figure 3 Shows a flowchart of a capacitance detection method provided according to some embodiments of the present application.

[0017] FIG. 4(a) shows a schematic diagram of a capacitance detection device in a first operating mode provided according to some embodiments of the present application.

[0018] FIG. 4(b) shows a schematic diagram of a capacitance detection device in a second operating mode provided according to some embodiments of the present application.

[0019] Figure 5 Shows a block diagram of a capacitance detection device provided according to some embodiments of the present application.

[0020] Figure 6 Shows a block diagram of a SoC (System on Chip) provided according to some embodiments of the present application Detailed implementation manners

[0021] The following will describe in detail the specific implementation manners of the present application with reference to the accompanying drawings.

[0022] Figure 1 Shows an application scenario of a capacitance detection device provided according to some embodiments of the present application. The capacitance detection device is introduced as an example of a touch sensor.

[0023] As Figure 1 shown, the touch sensor adopts a self-capacitance structure and includes a touch electrode plate. In other embodiments, the touch sensor may also adopt a mutual-capacitance structure, which is not specifically limited herein. Those skilled in the art can select the specific type of the touch sensor according to needs.

[0024] A parasitic capacitance C0 is formed between the touch electrode plate and the reference ground. When a finger approaches the touch electrode plate, a variable capacitance ΔC is formed between the finger and the touch electrode plate. Since the human body capacitance is relatively large and its potential is equivalent to that of the ground, during the process of the finger approaching the touch electrode plate, the capacitance C of the touch electrode plate to the ground x includes two parts, namely the parasitic capacitance C0 and the variable capacitance ΔC, that is, C x = C0 + ΔC. By detecting the magnitude of ΔC, it can be determined whether there is a touch by the finger and the touch position.

[0025] The touch sensor can be specifically applied to wearable devices (such as Figure 1 the watch 300 in Figure 1 shown, or a bracelet), mobile phones 200 (as Figure 1 shown), tablet computers, laptop computers, ultra-mobile personal computers (UMPCs), handheld computers, netbooks, personal digital assistants (PDAs), virtual reality devices, and other electronic devices with touch screens. The present application is not specifically limited thereto.

[0026] It can be understood that the capacitance detection method of the present application is applicable to the scenario where a capacitance detection device detects the capacitance of a capacitive sensor.

[0027] It can be understood that, as described above, in the prior art, the capacitance of the detection channel is affected not only by the proximity of the human body or a conductor, but also by environmental changes such as temperature, humidity, and air pressure. When the environmental changes are large, the change in the capacitance measurement value obtained by performing capacitance detection on the capacitance to be detected is comparable to the capacitance change caused by the proximity of the human body or a conductor to the capacitance to be detected, thereby affecting the capacitance detection accuracy and even causing the capacitance detection device to make a misjudgment and obtain an incorrect capacitance measurement value.

[0028] To solve the above problems, the embodiments of the present application provide a capacitance detection device and a capacitance detection method applied to the capacitance detection device. In some embodiments, the execution subject of the capacitance detection method is the capacitance detection device itself. It can be understood that in some embodiments of the present application, the capacitance detection device can implement capacitance detection in the form of a chip, and in other embodiments, the capacitance detection device can also implement capacitance detection in the form of a circuit. As long as it can implement capacitance detection, the embodiments of the present application do not make specific limitations on this.

[0029] The capacitance detection method according to the embodiments of the present application includes: obtaining the capacitance measurement value in the first working mode and the capacitance measurement value in the second working mode in two environmental states respectively. Among them, the first working mode includes applying a voltage signal consistent with the detection channel on the drive channel when performing capacitance detection on the detection channel through an excitation voltage signal; the second working mode includes applying a ground voltage signal on the drive channel when performing capacitance detection on the detection channel through an excitation voltage signal. Then, according to the capacitance measurement change value of the detection channel obtained in the first working mode and the capacitance measurement change value of the capacitance between the detection channel and the drive channel obtained in the second working mode, a compensation coefficient is determined, and according to the obtained compensation coefficient, the capacitance measurement value in the first working mode is compensated to obtain the compensated capacitance measurement value of the detection channel.

[0030] Through the above method, the change in the combined capacitance formed by the detection channel and the capacitance to be detected in different environments can be compensated according to the change in the capacitance between the drive channel and the detection channel in different environments, so that the environmental drift of the capacitance measurement value can be excluded, and a more accurate measurement value of the combined capacitance can be obtained.

[0031] The capacitive sensor can be specifically applied to electronic devices with touch screens, such as wearable devices (such as smart bracelets, smart watches, etc.), mobile phones, tablet computers, laptop computers, Ultra-Mobile Personal Computers (UMPCs), handheld computers, netbooks, Personal Digital Assistants (PDAs), virtual reality devices, etc. The embodiments of the present application do not make specific limitations on this.

[0032] The embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0033] Figure 2 The following is a schematic structural diagram of a capacitance detection device provided for some embodiments of the present application. As Figure 2 shown, the capacitance detection device 100 includes: a detection channel pin CS, a drive channel pin DRV, a capacitance digital conversion unit (which can be, for example, a capacitor digital converter, Capacitor Digital Conversion, CDC), a drive unit, and a data processing unit. The detection channel pin CS is used to connect to the detection channel trace 1, and the drive channel pin DRV is used to connect to the drive channel trace 2. In some possible embodiments, at least a part of the drive channel trace 2 is parallel to the detection channel trace 1, so as to ensure that the surrounding conditions of the drive channel and the detection channel are as consistent as possible, improve the compensation accuracy, and thus ensure the detection accuracy of the capacitance detection device 100. In this embodiment, the detection channel trace 1 and the drive channel trace 2 are the same and arranged in parallel to eliminate the influence of other variables on the detection result of the detection channel.

[0034] The capacitance digital conversion unit is respectively connected to the detection channel pin CS and the data processing unit, and is used to convert the capacitance to be detected 400 into a digital quantity and then transmit it to the data processing unit. The data processing unit is used to process the data output by the capacitance digital conversion unit to obtain a compensated capacitance measurement value. The drive unit is used to output a drive voltage signal.

[0035] The capacitance detection device 100 is presented in the form of a chip. In some other embodiments, the capacitance detection device 100 can also be in other forms, such as a circuit, which is not specifically limited herein as long as it can achieve the function of capacitance detection. The capacitance detection device 100 can be used to detect the capacitance value of the capacitance to be detected 400. In this embodiment, the capacitance to be detected 400 is a capacitance in a touch sensor (such as a SAR touch sensor).

[0036] The following combines the above Figure 1 and Figure 2 shown scenarios and combines Figure 3 , and details the technical solution of the present application. As Figure 3 shown, in some embodiments of the present application, the execution subject of the capacitance detection method can be a capacitance detection device, and the method can include the following steps:

[0037] Step S1, obtain a first capacitance measurement value of the capacitance to be detected in a first working mode in a first environmental state and a second capacitance measurement value in a second working mode.

[0038] It can be understood that when a capacitive sensor approaches a human body such as a finger or a conductor, it will cause a change in its own capacitance, so that it can judge whether a finger touches and the position of the touch. For the convenience of description, in the embodiments of the present application, the capacitive sensor is simplified to a capacitance to be detected, which is used to sense the change in capacitance when a human body or a conductor approaches.

[0039] Here, the capacitance value of the capacitance to be detected will be affected by the environment, and the capacitance measurement values detected during capacitance detection in different environmental states are different. The environmental parameters that affect the capacitance measurement value can include but are not limited to: temperature, humidity, air pressure, etc.

[0040] It can be understood that the capacitance to be detected may include the parasitic capacitance between the electrode plate of the capacitive sensor and the ground, may also include the mutual capacitance between the human body or the conductor and the electrode plate of the capacitive sensor, and may also include the combined capacitance formed by the parasitic capacitance between the electrode plate of the capacitive sensor and the ground and the mutual capacitance between the human body or the conductor and the electrode plate of the capacitive sensor. The embodiments of the present application do not make specific limitations on this.

[0041] It can be understood that when measuring the capacitance to be detected, there may be one environmental parameter that affects the capacitance measurement value, such as temperature alone having an impact, or humidity alone having an impact, or two or more environmental parameters may simultaneously affect the capacitance measurement value, such as temperature, humidity, and air pressure simultaneously affecting the capacitance measurement value. The embodiments of the present application do not make specific limitations on this.

[0042] In some embodiments of the present application, the capacitance detection of the capacitance to be detected includes two working modes: the first working mode and the second working mode. The voltage signals applied to the driving channels in the two working modes are different. By applying different voltage signals, the detected capacitance can be changed, thereby affecting the obtained capacitance measurement value.

[0043] In the first working mode, when the capacitance to be detected is capacitively detected through an excitation voltage signal in the detection channel, a voltage signal consistent with the detection channel is applied to the driving channel, as shown in FIG. 4(a). Here, when capacitively detecting the capacitance to be detected, the capacitance measurement related to the capacitance to be detected is realized by applying an excitation voltage to the detection channel connected to the capacitance to be detected.

[0044] As shown in FIG. 4(a), the detection channel trace is the trace for connecting the capacitance to be detected and the capacitance detection device, and the driving channel pin trace is the trace juxtaposed with the detection channel. Here, the juxtaposition means that the trace of the driving channel is basically parallel to the trace of the detection channel, that is, most of the traces of the detection channel and the driving channel are parallel, and only a small part of the traces are not parallel. Both the driving channel and the detection channel are connected to the capacitance detection device. The difference is that the driving channel is not connected to the capacitance to be detected, that is, it is floating, while the detection channel is connected to the capacitance to be detected.

[0045] Here, the self-capacitance value of the capacitor to be detected is denoted as C x , and the capacitance value of the detection channel trace is denoted as C trace . These two cannot be measured separately to obtain corresponding measurement values. Detecting the capacitance of the capacitor to be detected actually includes detecting the capacitance of the capacitor to be detected and the detection channel trace. The capacitance measurement value of the capacitor to be detected is denoted as C sensor , and there is the following formula:

[0046] C sensor = C x + C trace

[0047] Since both the detection channel and the drive channel are conductors, there is a parasitic capacitance C0 between the detection channel and the drive channel. When applying an excitation voltage through the detection channel for capacitance detection, the presence of the parasitic capacitance C0 will affect the capacitance measurement value.

[0048] In some embodiments of the present application, an actual capacitor C1 can be set between the detection channel and the drive channel. The capacitor C1 is a capacitor existing in a physical form, and setting the actual capacitor will also affect the capacitance measurement value.

[0049] It can be understood that an actual capacitor can be set between the detection channel and the drive channel, or it can not be set. In the case where no actual capacitor is set, the capacitance value of the capacitor C1 is regarded as 0. The embodiments of the present application do not make specific limitations on this.

[0050] In the first working mode, since the voltage signal applied on the drive channel is the same as that on the detection channel, that is, the waveform of the voltage applied on the drive channel is exactly the same as the waveform of the voltage applied on the detection channel, the potentials of the traces of the drive channel and the detection channel are equal, and the capacitance between them can be equivalent to 0, that is, the parasitic capacitance value and the actual capacitance value in Figure 4(a) are 0.

[0051] Therefore, the first capacitance measurement value obtained by detecting the capacitor to be detected in the first working mode includes the self-capacitance value of the capacitor to be detected and the capacitance value of the detection channel trace, and does not include the capacitance value between the detection channel and the drive channel. It is expressed by the formula as follows:

[0052] C sensor_m1 = C x + C trace (1)

[0053] Among them, C sensor_m1 represents the first capacitance measurement value obtained by detecting the capacitor to be detected in the first working mode.

[0054] In the second working mode, when the capacitance of the capacitor to be detected is detected through the excitation voltage signal in the detection channel, a ground voltage signal is applied to the drive channel, as shown in FIG. 4(b).

[0055] In the second working mode, since the ground voltage signal, i.e., the GND signal, is applied to the drive channel, a potential difference is formed between the drive channel and the detection channel. Therefore, when performing capacitance measurement, the parasitic capacitance and the actual capacitance between the drive channel and the detection channel will affect the capacitance measurement value. Thus, the second capacitance measurement value obtained by detecting the capacitor to be detected in the second working mode includes, in addition to the self-capacitance value of the capacitor to be detected and the capacitance value of the detection channel trace, the value of the parasitic capacitance and the value of the actual capacitance between the detection channel and the drive channel, which is expressed by the formula as follows:

[0056] C sensor_m2 =C x +C trace +CP (2)

[0057] Wherein, C sensor_m2 represents the second capacitance measurement value obtained by detecting the capacitor to be detected in the second working mode, CP is the sum of the value of the parasitic capacitance and the value of the actual capacitance, and CP = C0 + C1.

[0058] Step S2, obtain the third capacitance measurement value of the capacitor to be detected in the first working mode and the fourth capacitance measurement value in the second working mode in the second environmental state.

[0059] Here, compared with the first environment, the environmental parameters of the second environment have changed, causing changes in both the self-capacitance value of the capacitor to be detected and the capacitance value of the detection channel trace.

[0060] It can be understood that for the change of the second environment relative to the first environment, the environmental parameters such as temperature, humidity, air pressure, etc. can be a change in one parameter such as temperature, or a change in more than one parameter such as temperature and humidity. The embodiments of the present application do not make specific limitations thereto.

[0061] Similarly, in the second environment, when performing capacitance detection on the capacitor to be detected in the first working mode, a third capacitance measurement value is obtained. The third capacitance measurement value includes the changed self-capacitance value of the capacitor to be detected and the changed capacitance value of the detection channel trace, which is expressed by the formula as follows:

[0062] C’ sensor_m1 =C x +ΔC x +C trace +ΔC trace (3)

[0063] Wherein, C’ sensor_m1Represents the third capacitance measurement value obtained by performing capacitance detection on the capacitance to be detected in the first working mode, ΔC x Is the change in the self-capacitance value of the capacitance to be detected as the environmental state changes, ΔC trace Is the change in the capacitance value of the detection channel trace as the environmental state changes.

[0064] Then, perform capacitance detection on the capacitance to be detected in the second working mode to obtain a fourth capacitance measurement value. The fourth capacitance measurement value includes not only the self-capacitance value of the capacitance to be detected after the change and the capacitance value of the detection channel trace after the change, but also the value of the parasitic capacitance between the detection channel and the drive channel after the change and the value of the actual capacitance after the change. It is expressed by the formula as follows:

[0065] C’ sensor_m2 = C x + ΔC x + C trace + ΔC trace + CP + ΔCP (4)

[0066] Among them, C’ sensor_m2 Represents the fourth capacitance measurement value obtained by performing capacitance detection on the capacitance to be detected in the second working mode, and ΔCP is the change in the capacitance value of the parasitic capacitance and the actual capacitance as the environmental state changes.

[0067] Step S3, determine the capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value.

[0068] In some embodiments of the present application, the initial capacitance measurement values of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel can be obtained through the second capacitance measurement value obtained in the second working mode and the first capacitance measurement value obtained in the first working mode in the first environmental state. This capacitance measurement initial value is the first difference. That is, use formula (2) - formula (1), and it is expressed by the formula as follows:

[0069] C sensor_m2 - C sensor_m1 = CP (5)

[0070] In some embodiments of the present application, the capacitance measurement values of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel after the change can be obtained through the fourth capacitance measurement value obtained in the second working mode and the third capacitance measurement value obtained in the first working mode in the second environmental state. This capacitance measurement value is the second difference. That is, use formula (4) - formula (3), and it is expressed by the formula as follows:

[0071] C’ sensor_m2 - C’ sensor_m1= CP + ΔCP (6)

[0072] In some embodiments of the present application, by calculating the difference between the capacitance measurement value of the parasitic capacitance and the actual capacitance between the changed detection channel and the drive channel and the initial capacitance measurement value of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel, the capacitance measurement change value of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel can be obtained. This capacitance measurement change value is the third difference, that is, using formula (6) - formula (5), which is expressed as follows:

[0073] Δ(C’ sensor_m2 -C’ sensor_m1 ) = ΔCP (7)

[0074] Step S4: Determine the capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value.

[0075] In some embodiments of the present application, the first capacitance measurement value and the third capacitance measurement value obtained in the first working mode are only the capacitance measurement values obtained by detecting the capacitance of the capacitance to be detected and the detection channel trace. The third capacitance measurement value is the capacitance measurement value obtained after the capacitance of the capacitance to be detected and the detection channel trace also change after the environment changes, and it is a change based on the first capacitance measurement value. Therefore, by calculating the difference between the first capacitance measurement value and the third capacitance measurement value, the capacitance measurement change value of the detection channel can be determined. Here, the capacitance measurement change value of the detection channel includes the self-capacitance change value of the capacitance to be detected and the capacitance change value of the detection channel trace. That is, using formula (3) - formula (1), which is expressed as follows:

[0076] C’ sensor_m1 -C sensor_m1 =ΔC x +ΔC trace (8)

[0077] Step S5: Determine the compensation coefficient according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel.

[0078] In some embodiments of the present application, the ratio of the capacitance measurement change value of the detection channel and the capacitance measurement change value of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel can be calculated, and the compensation coefficient can be determined according to the ratio.

[0079] Here, the self-capacitance value of the capacitance to be detected, the capacitance value of the detection channel trace, the parasitic capacitance value between the detection channel and the drive channel, and the actual capacitance value will all change due to the influence of the environment. Through experiments, it is found that under certain trace and layout conditions, the change amount of the self-capacitance value of the capacitance to be detected and the change amount of the capacitance value of the detection channel trace are approximately in a fixed proportional relationship with the change amount of the parasitic capacitance value between the detection channel and the drive channel and the change amount of the actual capacitance value. Therefore, according to this proportional relationship, the change amounts of the capacitance to be detected and the capacitance value of the detection channel trace can be compensated by detecting the change amounts of the parasitic capacitance and the actual capacitance between the detection channel and the drive channel, and the capacitance values of the capacitance to be detected and the detection channel trace that can suppress environmental drift can be determined.

[0080] Determine the compensation coefficient K according to the above ratio, which is expressed by the formula as follows:

[0081]

[0082] Step S6: Compensate the third capacitance measurement value according to the compensation coefficient to obtain the compensated capacitance measurement value of the detection channel.

[0083] In some embodiments of the present application, the compensation value is determined according to the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel. Here, the product of the capacitance measurement change value of the capacitance between the detection channel and the drive channel and the compensation coefficient can be used to describe the change amounts of the capacitance to be detected and the capacitance value of the detection channel trace. The compensation value C comp is expressed by the formula as follows:

[0084] C comp = K·Δ(C’ sensor_m2 - C’ sensor_m1 ) = K·ΔCP (10)

[0085] In some embodiments of the present application, the capacitance measurement value in the first working mode in the current environmental state, that is, the third capacitance measurement value, is compensated according to the compensation value to obtain the compensated capacitance measurement value of the detection channel. Here, the compensated capacitance measurement value of the detection channel is the self-capacitance value of the capacitance to be detected and the capacitance value of the detection channel trace obtained after removing the capacitance value affected by environmental drift.

[0086] Specifically, calculate the difference between the third capacitance measurement value and the compensation value, and determine the compensated capacitance measurement value of the detection channel according to the obtained difference. It can be understood that the obtained difference can be directly determined as the compensated capacitance measurement value of the detection channel, or certain mathematical changes such as linear change or polynomial change can be performed on the obtained difference, and the change result is determined as the compensated capacitance measurement value of the detection channel. The embodiments of the present application do not make specific limitations on this.

[0087] Calculate the difference between the third capacitance measurement value and the compensation value, which is expressed by the following formula:

[0088] C”sensor = C’ sensor_m1 −C comp = C x + C trace + ΔC x + ΔC trace −K·ΔCP

[0089] = C x + C trace (11)

[0090] In the above formula, according to the transformation of formula (9), it can be known that ΔC x + ΔC trace = K·ΔCP, so ΔC x + ΔC trace −K·ΔCP = 0.

[0091] In addition to the method for determining the capacitance measurement value of the compensated detection channel in the above embodiments, the present application also provides a method for determining the capacitance measurement value of the compensated detection channel. The capacitance measurement value of the compensated detection channel is a function of the first capacitance measurement value and the second capacitance measurement value, that is, the capacitance measurement value of the compensated detection channel = f(C sensor_m1 , C sensor_m2 ).

[0092] In some possible embodiments, the capacitance measurement value of the compensated detection channel satisfies a linear relationship with the first capacitance measurement value and the second capacitance measurement value, that is, the capacitance measurement value of the compensated detection channel = K1×C sensor_m1 −K2×C sensor_m2 = (K1 - K2)×C x +(K1 - K2)×C trace −K2×CP (12)

[0093] In formula (12), K1 is the first compensation coefficient; K2 is the second compensation coefficient.

[0094] When the change amount of the capacitance of the capacitor 400 to be detected (such as Figure 1 the capacitance of the touch plate in) with the environment (such as temperature) is approximately in a fixed proportional relationship with the change amounts of the capacitance of the detection channel trace 1, the parasitic capacitance between the detection channel trace 1 and the drive channel trace 2, and the actual capacitance with the environment (such as temperature), by selecting appropriate first and second compensation coefficients, the capacitance measurement value of the compensated detection channel can be determined.

[0095] Figure 5A block diagram showing a capacitance detection device provided according to some embodiments of the present application. The capacitance detection device 100 includes: a detection capacitance sensor 110, a driving capacitance sensor 120, and a digital processing unit 130. The detection capacitance sensor 110 is configured to obtain a first capacitance measurement value of the detection channel in a first working mode in a first environmental state and a third capacitance measurement value of the detection channel in the first working mode in a second environmental state.

[0096] The driving capacitance sensor 120 is configured to obtain a second capacitance measurement value of the detection channel in a second working mode in the first environmental state and a fourth capacitance measurement value of the detection channel in the second working mode in the second environmental state.

[0097] The digital processing unit 130 is configured to determine a capacitance measurement change value of the capacitance between the detection channel and the driving channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value, determine a capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value, and determine a compensated capacitance measurement value of the detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the driving channel.

[0098] Figure 6 A block diagram showing a SoC (System on Chip) provided according to some embodiments of the present application. In Figure 6 , similar components have the same reference numerals. Additionally, the dashed boxes are optional features of a more advanced SoC. In Figure 6 , the SoC 1500 includes: an interconnect unit 1550, which is coupled to an application processor 1515; a system agent unit 1570; a bus controller unit 1580; an integrated memory controller unit 1540; one or a group of co-processors 1520, which may include integrated graphics logic, an image processor, an audio processor, and a video processor; a static random access memory (SRAM) unit 1530; a direct memory access (DMA) unit 1560. In one embodiment, the co-processor 1520 includes a dedicated processor, such as, for example, a network or communication processor, a compression engine, a GPGPU, a high-throughput MIC processor, or an embedded processor, etc.

[0099] According to the capacitance detection method and capacitance detection device provided by the present application, it can correct the capacitance change caused by environmental changes, thereby ensuring the capacitance detection accuracy and avoiding misjudgment.

[0100] Embodiments of the mechanisms disclosed in this application may be implemented in hardware, software, firmware, or a combination of these implementation methods. Embodiments of this application may be implemented as a computer program or program code executed on a programmable system, which includes at least one processor, a storage system (including volatile and non-volatile memories and / or storage elements), at least one input device, and at least one output device.

[0101] The program code may be applied to input instructions to perform the various functions described in this application and generate output information. The output information may be applied to one or more output devices in a known manner. For the purposes of this application, a processing system includes any system having a processor such as, for example, a Digital Signal Processor (DSP), a microcontroller, an Application Specific Integrated Circuit (ASIC), or a microprocessor.

[0102] The program code may be implemented in a high-level procedural language or an object-oriented programming language in order to communicate with the processing system. When necessary, the program code may also be implemented in assembly language or machine language. In fact, the mechanisms described in this application are not limited to the scope of any particular programming language. In either case, the language may be a compiled language or an interpreted language.

[0103] In some cases, the disclosed embodiments may be implemented in hardware, firmware, software, or any combination thereof. The disclosed embodiments may also be implemented as instructions carried or stored on one or more transient or non-transitory machine-readable (e.g., computer-readable) storage media, which may be read and executed by one or more processors. For example, the instructions may be distributed via a network or via other computer-readable media. Thus, machine-readable media can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer), including but not limited to, floppy disks, optical disks, optical discs, CD-ROMs, magneto-optical disks, read only memory (ROM), random access memory (RAM), erasable programmable read only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic or optical cards, flash memory, or tangible machine-readable memories for transmitting information (e.g., carrier waves, infrared signals, digital signals, etc.) in electrical, optical, acoustic, or other forms using the Internet. Thus, machine-readable media includes any type of machine-readable media suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0104] In the drawings, some structural or method features may be shown in a particular arrangement and / or order. However, it should be understood that such a particular arrangement and / or ordering may not be required. Rather, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. Additionally, the inclusion of a structural or method feature in a particular figure does not imply that such a feature is required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0105] It should be noted that the units / modules mentioned in the device embodiments of this application are all logical units / modules. Physically, a logical unit / module may be a physical unit / module, may be a part of a physical unit / module, or may also be implemented as a combination of multiple physical units / modules. The physical implementation manner of these logical units / modules themselves is not the most important. The combination of the functions implemented by these logical units / modules is the key to solving the technical problems proposed by this application. In addition, in order to highlight the innovative part of this application, the above device embodiments of this application do not introduce units / modules that are not closely related to solving the technical problems proposed by this application. This does not mean that there are no other units / modules in the above device embodiments.

[0106] It should be noted that in the examples and the description of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0107] Although this application has been illustrated and described by reference to certain preferred embodiments thereof, those of ordinary skill in the art should understand that various changes may be made therein in form and detail without departing from the spirit and scope of this application.

Claims

1. A capacitance detection method for a capacitance detection device, characterized in that, The method includes: Obtaining a first capacitance measurement value in a first working mode of a detection channel in a first environmental state and a second capacitance measurement value in a second working mode, where the first working mode includes applying a voltage signal consistent with the detection channel on a drive channel when the detection channel performs capacitance detection on a capacitance to be detected through an excitation voltage signal; the second working mode includes applying a ground voltage signal on the drive channel when the detection channel performs capacitance detection on the capacitance to be detected through the excitation voltage signal; the detection channel includes a trace for connecting the capacitance to be detected and the capacitance detection device, and one end of the drive channel is connected to the capacitance detection device and the other end is floating; Obtaining a third capacitance measurement value in the first working mode of the detection channel in a second environmental state and a fourth capacitance measurement value in the second working mode, where the environmental parameters of the second environmental state are different from those of the first environmental state; Determining a capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value; Determining a capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value; Determining a compensated capacitance measurement value of the detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel; Wherein, determining a compensated capacitance measurement value of the detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel includes: Determining a compensation coefficient according to the ratio of the capacitance measurement change value of the detection channel to the capacitance measurement change value of the capacitance between the detection channel and the drive channel; Determining a compensated capacitance measurement value of the detection channel according to the compensation coefficient.

2. The method according to claim 1, wherein The capacitance between the detection channel and the drive channel includes at least one of the following: the parasitic capacitance between the detection channel and the drive channel, and the capacitance connected to the detection channel and the drive channel.

3. The method according to claim 1, characterized in that, Determining a capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value includes: Obtaining a first difference between the second capacitance measurement value and the first capacitance measurement value; Obtaining a second difference between the fourth capacitance measurement value and the third capacitance measurement value; Calculating a third difference between the first difference and the second difference; Determining a capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the third difference.

4. The method according to claim 1, wherein Determining a compensated capacitance measurement value of the detection channel according to the compensation coefficient includes: Determine the capacitance measurement value of the compensated detection channel according to the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel.

5. The method according to claim 4, wherein Determining the capacitance measurement value of the compensated detection channel according to the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel includes: Determine the capacitance measurement value of the compensated detection channel according to the difference between the third capacitance measurement value and the product of the compensation coefficient and the capacitance measurement change value of the capacitance between the detection channel and the drive channel.

6. A capacitance detection device, which adopts the capacitance detection method according to any one of claims 1 to 5, characterized in that, Including: A detection capacitance sensor for obtaining a first capacitance measurement value of the detection channel in a first operating mode in a first environmental state and a third capacitance measurement value of the detection channel in a first operating mode in a second environmental state; A drive capacitance sensor for obtaining a second capacitance measurement value of the detection channel in a second operating mode in a first environmental state and a fourth capacitance measurement value of the detection channel in a second operating mode in a second environmental state; A digital processing unit for determining the capacitance measurement change value of the capacitance between the detection channel and the drive channel according to the difference between the second capacitance measurement value and the first capacitance measurement value and the difference between the fourth capacitance measurement value and the third capacitance measurement value, determining the capacitance measurement change value of the detection channel according to the difference between the first capacitance measurement value and the third capacitance measurement value, and determining the capacitance measurement value of the compensated detection channel according to the capacitance measurement change value of the detection channel and the capacitance measurement change value of the capacitance between the detection channel and the drive channel; The digital processing unit is further configured to determine a compensation coefficient according to the ratio of the capacitance measurement change value of the detection channel to the capacitance measurement change value of the capacitance between the detection channel and the drive channel; and determine the capacitance measurement value of the compensated detection channel according to the compensation coefficient.

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