TWI425404B - Proximity detection method for a capacitive touchpad and control method using proximity detection by a capacitive touchpad - Google Patents

Description

Method for detecting proximity of capacitive touch panel and control method for proximity detection using capacitive touch panel

The present invention relates to a capacitive touch panel, and more particularly to a proximity detection method for a capacitive touch panel and a control method for proximity detection using the capacitive touch panel.

At present, the mainstream touch technology has two types of resistance and capacitance. The resistive touch panel uses the principle of resistance voltage division to locate the contact point, and the capacitive touch panel locates the contact point by detecting the change of the capacitance value. Some devices currently have a proximity detection function, but whether it uses a resistive or capacitive touch panel, the proximity detection function is achieved by an optical sensor. The optical sensor is disposed near the touchpad, and when an object approaches the touchpad, the optical sensor detects the object and notifies the device. However, the proximity detection method using an optical sensor increases the cost of the optical sensor and its back-end circuit, and it is more necessary to consider the space in which the optical sensor is disposed.

Therefore, a method of achieving proximity detection using the capacitive touch panel itself is a problem.

One of the objects of the present invention is to provide a proximity detection method for a capacitive touch panel.

One of the objects of the present invention is to propose a control method for proximity detection using a capacitive touch panel.

According to the present invention, a proximity detection method for a capacitive touch panel includes simultaneously applying a second modulation signal in phase with the first modulation signal to drive a plurality of non-derivatives when a first modulation signal is applied to drive the measured sensing line. The measured sensing line demodulates the signal generated from the measured sensing line to obtain a detection value, and determines whether an object is close to the capacitive touch panel according to the magnitude of the detected value.

According to the present invention, a proximity detection method for a capacitive touch panel includes applying a same modulated signal to drive a plurality of sensing lines, demodulating a signal generated therefrom to obtain a detected value, and determining whether an object is present according to the magnitude of the detected value. Close to the capacitive touch panel.

According to the present invention, a method for controlling proximity detection using a capacitive touch panel includes operating the capacitive touch panel in proximity detection to determine whether an object is in proximity, and if the object is close, switching the capacitive touch The board operates on position detection to detect the position of the object.

According to the present invention, a method for controlling proximity detection using a capacitive touch panel includes operating the capacitive touch panel on proximity detection to determine whether an object is in proximity, and if the object is close, locking the capacitive touch The board is prohibited from operating in position detection to avoid malfunction.

According to the present invention, a method for controlling proximity detection using a capacitive touch panel includes operating the capacitive touch panel in proximity detection to determine whether an object is in proximity, and if the object is in proximity, and using the capacitive touch The system of the board is in the standby state, then the system is woken up.

1 is a capacitive touch panel system used in the present invention. The touch panel 10 includes an X-axis sensing line 12 and a Y-axis sensing line 14. The analog multiplexer 16 selects one or more connection modulators from the sensing lines. 18, the modulator 18 is a current source, the frequency and current are adjustable, and the modulated signal D1, D2 is applied to the selected sensing line, charged and discharged, and the sensing line connected by the modulated signal D1 is connected. The demodulator 20 is demodulated, and the sensing line driven by the modulated signal D2 is not connected to the demodulator 20. The sensing line to be driven by the modulated signals D1, D2 is selected by the firmware of the microcontroller 22. The system initializes before the detection, adjusts the current provided by the modulator 18 and the analogy parameters of the components in the back-end circuit 24, so that the demodulated signal of the demodulator 20 passes through the back-end circuit 24 and the analog-to-digital conversion. The detected value obtained by the (ADC) 26 falls within a preset range for the microcontroller 22 to read.

2 is a voltage waveform generated by the modulator 18 for charging and discharging the sensing line. If no object is close to the measured sensing line, the voltage signal detected from the waveform is waveform 28; if an object is close to the measured sensing line, The capacitance of the sensed line increases, so the voltage signal detected from it becomes waveform 30. The demodulator 20 demodulates the waveform 28 or 30 to generate a DC voltage signal. The DC level when no object is close is V1, and when the object is close, it is a small DC level V2. From the difference between the DC levels V1 and V2, the amount of change in the capacitance value of the measured sensing line can be estimated to determine whether an object exists.

Figure 3 is a first embodiment of the present invention. When the sensing line 32 is detected, the modulation signal D1 is applied to drive the sensing line 32 and demodulated to detect its capacitance value. When the sensing line 32 is driven by the modulation signal D1, the sensing lines 12, 14 are driven in synchronization with the modulation signal D2 in phase with the modulation signal D1 to reduce the parasitic capacitance between the sensing line 32 and the remaining sensing lines 12, 14. The effect is not demodulated by the sensing lines 12, 14 that are driven by the modulation signal D2.

FIG. 4 is a comparison of the position detection and the projection of the change in the capacitance value detected from the X-axis and the Y-axis as shown in FIG. Position detection is a conventional technique that detects the change in capacitance value for each X-axis and Y-axis sensing line separately, and obtains waveforms 34 and 36, and varies according to the capacitance value of each sensing line. Perform an internal difference operation to get the exact position where the object touches. Position detection is not effective for proximity detection due to its low sensitivity. Using the proximity detection of FIG. 3, the sensitivity is much higher than the positioning detection. When the object approaches the capacitive touch panel, the projection waveforms 38 and 40 of the variation of the capacitance values of the X-axis and the Y-axis float up, which is easy to judge. Some objects are close.

Figure 5 is a second embodiment of the present invention. In the proximity detection, all the X-axis and Y-axis sensing lines 12, 14 are regarded as the sensed sensing line, and the modulated signal D1 is applied and demodulated, thereby measuring the amount of change in the total capacitance value. Then according to whether there is an object close.

Figure 6 is a third embodiment of the present invention. The capacitive touch panel has a shielding layer 42 under the sensing line, and is mainly used for shielding noise from below to avoid interference with the detection of the sensing lines. The capacitive touch panel is usually fixed on the metal frame or the liquid crystal display module of the casing. The metal frame 44 in FIG. 6 indicates the metal frame of the casing or the grounding strip of the liquid crystal display module. In this embodiment, in addition to providing the modulated signal to drive the sensing line as shown in FIG. 3 or FIG. 5, the modulated signal D2 is applied synchronously to the shielding layer 42 and the peripheral metal frame 44 to reduce the influence of the ground plane. This increases the effective detection distance for proximity detection. In other embodiments, the modulation signal D2 may also be applied synchronously in both the shielding layer 42 and the peripheral metal frame 44.

The proximity detection achieved by the capacitive touch panel itself can be used to control the capacitive touch panel or its connected system, for example, the capacitive touch panel is operated for proximity detection, and once an object is detected, the object is detected. , then switch to the location of the location to get the exact location of the object. 7 and 8 are flow charts of an embodiment. Referring to FIG. 7, when the system starts to operate, the initialization is first performed, and the proximity detection calibration program S46 and the positioning detection calibration program S48 are respectively performed, and both of them include the analogy parameters and settings required for loading, and the correction is performed to make the measurement. The resulting output signal falls within a predetermined range and the correction value is stored. After these correction procedures, the proximity detection flag is preset to 1 in step S50 to complete preparation before detection. Referring to FIG. 8 , initially, since the proximity detection flag is preset to 1, after the proximity detection flag is viewed in step S52, the proximity detection setting is loaded in step S54, and the approaching step S56 is performed. The detected value is detected, and compared with the switching threshold value in step S58, if the detected value is higher than the switching threshold value, it is determined that the object is close, and then the flag of the proximity detection is set to 0 in step S60. After performing a detection, the process returns to step S52 to view the flag of the proximity detection. If the proximity detection flag is 0, the location detection setting is loaded in step S62, and then the location detection is performed in step S64 to obtain the detection value, and the minimum threshold value is compared in step S66. If the detected value is not greater than the minimum threshold, it means that no object is detected, and the proximity detection flag is set to 1 in step S68, so that the next detection is changed to proximity detection. If the detected value is greater than the minimum threshold value, the internal difference operation is performed according to the amount of change in the capacitance value to obtain the precise position of the object. In other embodiments, a counting parameter may be added to count the number of detections, and when the number of detections reaches a preset value, it switches to another detection mode.

On the other hand, the capacitive touch panel can be sensed for the conductor, so the proximity detection of the capacitive touch panel can distinguish the size of the object. For example, when a user holds a capacitive touch mobile phone close to the cheek, the touch input may occur due to the cheek touching the capacitive touch panel, resulting in malfunction. If the proximity detection of the present invention is used to distinguish the size of the object, such as a finger or a cheek, and the touchpad enters the lock mode, the touch of the object on the touchpad can be ignored to avoid errors. Fig. 9 is a flow chart of an embodiment, and the previous correction flow is the same as that shown in Fig. 7. Referring to FIG. 9, initially, since the proximity detection flag is preset to 1, after the proximity detection flag is viewed in step S70, the proximity detection setting is loaded in step S72, and the proximity detection in step S74 is performed. The detected value is obtained, and then step S76 is compared with the anti-false threshold value, and the anti-false threshold value is larger than the switching threshold value in FIG. 8 for detecting a larger object, such as a large-area conductor of the cheek. If the detection value is greater than the anti-error threshold, it is determined that a larger object is approaching, so to step S78, the capacitive touch panel is temporarily locked from being operated for positioning detection, and then returning to step S70; if the detection value is less than If the value of the error prevention threshold is determined, it is determined that no larger object is approaching, and then the flag of the proximity detection is set to 0 in step S80. After performing a detection, the process returns to step S70 to view the flag of the proximity detection. If the flag of the proximity detection is 0, the setting of the position detection is loaded in step S82, and then the detection value is obtained by performing the position detection in step S84, and compared with the minimum threshold value in step S86. If the detected value is not greater than the minimum threshold, it means that no object is detected, and the proximity detection flag is set to 1 in step S88, so that the next detection is changed to proximity detection. If the detected value is greater than the minimum threshold value, the internal difference operation is performed according to the amount of change in the capacitance value to obtain the precise position of the object. When no object is close, the capacitive touch panel will switch between proximity detection and positioning detection. When the close object is a small object such as a finger or an input pen, it will stay in the position detection and positioning object. Precise location.

In addition to the above two embodiments for controlling the capacitive touch panel, the proximity detection of the present invention can be applied to achieve power saving and shorten the wake-up time. For example, in the standby mode, the capacitive touch panel performs proximity detection, and thus the capacitive touch panel itself and the system using the capacitive touch panel can reduce power consumption. When an object is detected to be close, the capacitive touch panel wakes up the system, so the user does not have to wait for the wake-up time of the system.

The above description of the preferred embodiments of the present invention is intended to be illustrative, and is not intended to limit the scope of the invention to the disclosed embodiments. It is possible to make modifications or variations based on the above teachings or learning from the embodiments of the present invention. The embodiments are described and illustrated in the practical application of the present invention in various embodiments, and the technical idea of the present invention is intended to be equivalent to the scope of the following claims. Decide.

10. . . touchpad

12. . . X-axis sensing line

14. . . Y-axis sensing line

16. . . Analog multiplexer

18. . . Modulator

20. . . Demodulator

twenty two. . . Microcontroller

twenty four. . . Backend circuit

26. . . Analog digital converter

28. . . Voltage waveform

30. . . Voltage waveform

32. . . Measured sensing line

34. . . Waveform

36. . . Waveform

38. . . Waveform

40. . . Waveform

42. . . Shield

44. . . Peripheral metal frame

1 is a capacitive touch panel system used in the present invention;

2 is a voltage waveform diagram generated by a modulator for charging and discharging a sensing line;

Figure 3 is a first embodiment of the proximity detecting method of the present invention;

Figure 4 is a projection view of the amount of change in the capacitance value of the positioning detection and the proximity detection;

Figure 5 is a second embodiment of the proximity detecting method of the present invention;

Figure 6 is a third embodiment of the proximity detecting method of the present invention;

7 is a flow chart of correction of a proximity touch sensitive touch panel of the present invention;

8 is a first embodiment of a proximity detection control capacitive touch panel to which the present invention is applied;

9 is a second embodiment of a proximity detection control capacitive touch panel to which the present invention is applied.

12. . . X-axis sensing line

14. . . Y-axis sensing line

32. . . Measured sensing line

Claims (21)

A proximity sensing method for a capacitive touch panel, the capacitive touch panel having a plurality of sensing lines arranged in parallel, the proximity detecting method comprising: simultaneously applying a first modulated signal to drive the measured sensing line The second modulated signal of the first modulated signal in phase drives a plurality of non-measured sensing lines; the signal generated from the measured sensing line is demodulated to obtain a detected value; the detected value and the threshold value are compared; and If the detection value is greater than the threshold value, it is determined that an object is close to the capacitive touch panel; wherein the detection value is a change corresponding to the capacitance value of the sensing line to be tested. The method of claim 1, further comprising applying the second modulation signal to the shielding layer of the capacitive touch panel. The method of claim 1, further comprising applying the second modulation signal to the metal frame on the periphery of the capacitive touch panel. A proximity sensing method for a capacitive touch panel, the capacitive touch panel having a plurality of sensing lines arranged in parallel, the proximity detecting method comprising: applying a first modulation signal to drive the plurality of sensing lines; Demodulating the signal generated by the sensing line to obtain the detected value; comparing the detected value with the threshold value; and if the detected value is greater than the threshold value, determining that an object is close to the capacitive touch panel; wherein the detected value It is the change of the total capacitance value of multiple sensing lines. The method of claim 4, further comprising applying a second modulation signal in phase with the first modulation signal of the shielding layer of the capacitive touch panel. The method of claim 4, further comprising applying a second modulation signal in phase with the first modulation signal to the metal frame on the periphery of the capacitive touch panel. A proximity sensing control method using a capacitive touch panel, the capacitive touch panel having a plurality of sensing lines arranged in parallel, the proximity detecting method comprising: operating the capacitive touch panel in proximity detection to determine Whether the object is close to; and if the object is close, switching the capacitive touch panel to operate in the position detection to obtain the position of the object; wherein the proximity detection is based on the change of the capacitance value of the plurality of sensing lines Determining whether an object is in proximity; the positioning detection is based on a change in a capacitance value of the plurality of sensing lines to obtain a position of the object. The method of claim 7, wherein the step of operating the capacitive touch panel on the proximity detection to determine whether an object is in proximity comprises: simultaneously applying the first modulation signal to drive the measured sensing line a second modulated signal in phase with the modulated signal drives a plurality of unmeasured sensing lines; demodulates the signal generated from the measured sensing line to obtain a detected value; compares the detected value with a threshold value; and if the detecting If the value is greater than the threshold value, it is determined that an object is close to the capacitive touch panel; wherein the detection value is a change corresponding to the capacitance value of the sensing line to be tested. The method of claim 7, wherein the step of operating the capacitive touch panel on proximity detection to determine whether an object is in proximity comprises: applying a first modulation signal to drive a plurality of sensing lines; generating from the plurality of sensing lines The signal demodulation obtains the detection value; compares the detection value with the threshold value; and if the detection value is greater than the threshold value, it determines that an object is close to the capacitive touch panel; wherein the detection value corresponds to The change in the total capacitance of multiple sense lines. The method of claim 8 or 9, further comprising shielding the capacitive touch panel Add the second modulation signal. The method of claim 8 or 9, further comprising applying the second modulation signal to the metal frame on the periphery of the capacitive touch panel. A method for controlling proximity detection using a capacitive touch panel includes: operating the capacitive touch panel to proximity detection to generate a detection value for determining whether an object is in proximity; and if the object is close to the detection If the value is greater than the first threshold, the capacitive touch panel is locked from being operated on the positioning detection to avoid malfunction. The method of claim 12, wherein the step of operating the capacitive touch panel on proximity detection to determine whether an object is in proximity comprises: simultaneously applying the first modulation signal to drive the measured sensing line a second modulated signal in phase with the modulated signal drives a plurality of unmeasured sensing lines; demodulating the signal generated from the measured sensing line to obtain the detected value; comparing the detected value with the second threshold; and The detection value is greater than the second threshold value, and it is determined that an object is close to the capacitive touch panel; wherein the detection value is a change corresponding to a capacitance value of the sensing line to be tested. The method of claim 12, wherein the step of operating the capacitive touch panel on proximity detection to determine whether an object is in proximity comprises: applying a first modulation signal to drive the plurality of sensing lines; generating from the plurality of sensing lines Demodulating the signal to obtain the detected value; comparing the detected value with the second threshold; and if the detected value is greater than the second threshold, determining that an object is close to the capacitive touch panel; The detection value is a change corresponding to the total capacitance value of the plurality of sensing lines. The method of claim 13 or 14, further comprising applying the second modulation signal to the shielding layer of the capacitive touch panel. The method of claim 13 or 14, further comprising applying the second modulation signal to the metal frame on the periphery of the capacitive touch panel. A method for controlling proximity detection using a capacitive touch panel includes: operating the capacitive touch panel to proximity detection to determine whether an object is in proximity; and if the object is in proximity, and using the capacitive touch panel The system wakes up in the standby state. The method of claim 17, wherein the step of operating the capacitive touch panel on proximity detection to determine whether an object is in proximity comprises: simultaneously applying the first modulation signal to drive the measured sensing line a second modulated signal in phase with the modulated signal drives a plurality of unmeasured sensing lines; demodulates the signal generated from the measured sensing line to obtain a detected value; compares the detected value with a threshold value; and if the detecting If the value is greater than the threshold value, it is determined that an object is close to the capacitive touch panel; wherein the detection value is a change corresponding to the capacitance value of the sensing line to be tested. The method of claim 17, wherein the step of operating the capacitive touch panel on proximity detection to determine whether an object is in proximity comprises: applying a first modulation signal to drive the plurality of sensing lines; generating from the plurality of sensing lines The signal demodulation obtains the detection value; compares the detection value with the threshold value; and if the detection value is greater than the threshold value, it determines that an object is close to the capacitive touch panel; wherein the detection value corresponds to The change in the total capacitance of multiple sense lines. The method of claim 18 or 19, further comprising applying the second modulation signal to the shielding layer of the capacitive touch panel. The method of claim 18 or 19, further comprising applying the second modulation signal to the metal frame on the periphery of the capacitive touch panel.