Touch panel and control method thereof
By adjusting the demodulation frequency in the touch panel to match the modulation frequency, the problem of reduced writing signal energy caused by frequency mismatch was solved, improving the accuracy and sensitivity of active pen touch and enhancing the user experience.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NOVATEK MICROELECTRONICS CORP
- Filing Date
- 2024-12-27
- Publication Date
- 2026-05-01
AI Technical Summary
In existing technologies, when a touch panel is used with an active pen, the energy of the demodulated writing signal decreases due to the mismatch between the modulation and demodulation frequencies, which affects the accuracy and sensitivity of writing event judgment and reduces the user experience.
By cooperating with the receiver and processor, the writing signal of the active pen is demodulated using the demodulation frequency, and its abnormality is judged. If an abnormality is found, the demodulation frequency is adjusted to increase the writing signal energy, and the modulation and demodulation frequencies are matched to improve the signal energy.
It effectively eliminates the frequency mismatch problem, improves the accuracy and sensitivity of active pen touch control, and enhances the user experience.
Smart Images
Figure CN121957375A_ABST
Abstract
Description
Touch panel and its control method Technical Field
[0001] This disclosure relates to a panel and a method, and more particularly, to a touch panel and a method for controlling the same. Background Technology
[0002] Today, touch control is widely used in various electronic devices. In particular, using an active stylus for touch control offers better accuracy and greater comfort, making it a preferred touch control option for more users. Summary of the Invention
[0003] Therefore, this disclosure aims to provide a touch panel and control method for eliminating the mismatch between modulation and demodulation frequencies.
[0004] The control method disclosed herein is applied to a touch panel to receive control from an active pen. The control method includes using a demodulation frequency to demodulate a writing signal received from the active pen; determining whether the demodulated writing signal is abnormal; and, in response to determining that the demodulated writing signal is abnormal, adjusting the demodulation frequency to increase the energy of the demodulated writing signal.
[0005] The disclosed touch panel is suitable for receiving control from an active pen. The touch panel includes a receiver and a processor. The receiver is configured to demodulate a writing signal received from the active pen using a demodulation frequency. The processor is coupled to the receiver. The processor is configured to determine whether the demodulated writing signal is abnormal; and in response to determining that the demodulated writing signal is abnormal, adjust the demodulation frequency to increase the energy of the demodulated writing signal.
[0006] To make the above content clearer and easier to understand, several embodiments are provided below, along with detailed descriptions in conjunction with the accompanying drawings. Attached Figure Description
[0007] The accompanying drawings, which are included and form part of this specification, are provided to provide a further understanding of this disclosure. These drawings illustrate exemplary embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure.
[0008] Figure 1 shows a schematic diagram of an electronic system according to some embodiments of the present disclosure;
[0009] Figures 2A to 2C illustrate handwritten judgment processes according to some embodiments of this disclosure;
[0010] Figures 3A to 3C illustrate handwritten judgment processes according to some embodiments of this disclosure;
[0011] Figure 4 shows a flowchart of a control method according to some embodiments of the present disclosure;
[0012] Figure 5A shows a timing diagram of a touch panel sensing a writing signal WS according to some embodiments of the present disclosure;
[0013] Figure 5B shows a timing diagram of a touch panel sensing a writing signal WS according to some embodiments of the present disclosure;
[0014] Figure 6A shows the energy spectrum of demodulated written signals demodulated at different demodulation frequencies in some embodiments according to this disclosure;
[0015] Figure 6B illustrates how the demodulation frequency is scanned according to some embodiments of this disclosure;
[0016] Figure 6C illustrates how the first frequency is adjusted according to some embodiments of this disclosure;
[0017] Figure 6D illustrates how the second frequency is adjusted in some embodiments according to this disclosure. Detailed Implementation
[0018] Figure 1 shows a schematic diagram of an electronic system 1 according to some embodiments of the present disclosure. The electronic system 1 includes a touch panel 10 and an active pen 11. The active pen 11 may internally house a battery, transmitter, and necessary processing circuitry to transmit writing signals independently. The touch panel 10 may be configured to receive writing signals from the active pen 11 when the active pen 11 approaches or touches a sensing surface on the touch panel 10, such that the touch panel 10 can recognize a touch from the active pen 11 in response to receiving the writing signal. In this way, a user can use the active pen 11 (e.g., to select and press a specific button displayed on the touch panel) to input handwriting or drawing onto the touch panel 10.
[0019] Specifically, the touch panel 10 includes a receiver 100 and a processor 101. The receiver 100 is configured to receive a writing signal WS from an active pen 11. The receiver 100 is configured to demodulate the writing signal WS using a modulation frequency to generate a demodulated writing signal DWS. Furthermore, the demodulated writing signal DWS can be transmitted to the processor 101 coupled to the receiver 100. The processor 101 is configured to determine whether a writing event is in progress based on the demodulated writing signal DWS, and to perform corresponding control operations. Additionally, the processor 101 is configured to determine whether the demodulated writing signal DWS is abnormal. When the demodulated writing signal DWS is determined to be abnormal, the processor 101 can control the receiver 100 to calibrate the demodulation frequency.
[0020] In some embodiments, the writing signal WS transmitted by the active pen 11 is modulated at a modulation frequency. To verify whether the writing signal WS is transmitted by the active pen 11, the receiver 100 may be configured to demodulate the received writing signal WS at a demodulation frequency, so that the processor 101 may be configured to determine whether the active pen 11 is in contact with the touch panel 10 based on the demodulated writing signal DWS. The processor 101 may be configured to determine whether a writing event has occurred based on the energy of the demodulated writing signal DWS. If the energy of the demodulated writing signal DWS is greater than or equal to a threshold energy, the processor 101 may determine that the writing signal WS is sent by the active pen 11 and that the active pen 11 is sufficiently close to the touch panel 10, and therefore may determine that a writing event is occurring. To perform the corresponding operation indicated by the writing signal WS, the coordinate information of the point on the touch panel 10 where the writing signal WS is received may also be provided to the processor 101 for further control. On the other hand, if the energy of the demodulated writing signal DWS is less than the threshold energy, the processor 101 may determine that the writing signal WS may not be sent by the active pen 11 or that the active pen 11 is too far from the touch panel 10, and therefore may determine that no writing event has occurred.
[0021] Figures 2A to 2C illustrate the process of determining handwriting HW1 according to some embodiments of this disclosure.
[0022] When receiver 100 receives the writing signal WS, the writing signal WS can be demodulated by receiver 100 at a demodulation frequency to generate a demodulated writing signal DWS. Then, processor 101 can be configured to determine whether a writing event has occurred by comparing the energy of the demodulated writing signal DWS with a threshold energy TE. As depicted in FIG2B, the energy of the demodulated writing signal DWS is maintained at a level higher than the threshold energy TE and sufficiently high, therefore processor 101 can be configured to determine that a writing event WE1 is in progress. In addition, processor 101 can be configured to perform corresponding operations based on the determined writing event and the corresponding coordinate information. In this embodiment, the active pen 11 can be controlled to perform drawing or handwriting operations, therefore processor 101 can control the display panel of touch panel 10 to display the continuous handwriting HW1 depicted in FIG2C.
[0023] Figures 3A to 3C illustrate the process of determining handwriting HW2 according to some embodiments of this disclosure.
[0024] In this embodiment, the demodulation frequency used by the receiver 100 to demodulate the writing signal WS may deviate from the modulation frequency used by the active pen 11 to modulate the writing signal WS. Consequently, the energy of the demodulated writing signal DWS may drop to a lower level. More specifically, the energy of the demodulated writing signal DWS may occasionally drop below a threshold energy TE. Therefore, when comparing the energy of the demodulated writing signal DWS with the threshold energy TE, the comparison result becomes unstable, which also leads to unstable judgment of touch events. Specifically, as shown in FIG3B, based on the comparison of the energy of the demodulated writing signal DWS with the threshold energy TE, the processor 101 can be configured to judge multiple writing events WE21 to WE26. Therefore, in this embodiment, the processor 101 can control the display panel to display the intermittent handwriting HW2 depicted in FIG3C.
[0025] In short, the mismatch between the modulation and demodulation frequencies will cause a decrease in the energy of the demodulated writing signal, affecting the processor 101's judgment of writing events. As shown in Figure 3C, due to the frequency mismatch, the handwriting HW2 is divided into multiple line segments, which are displayed as discontinuous lines on the touch panel 10. Therefore, the mismatch between the modulation and demodulation frequencies will cause the touch panel 10 to incorrectly judge the touch from the active pen 11, thereby affecting the accuracy and sensitivity of the active pen 11's touch control and reducing the user's experience with the electronic system 1.
[0026] Figure 4 shows a flowchart of a control method according to some embodiments of this disclosure. The control method in Figure 4 can be executed by the touch panel 10 in Figure 1. In short, the control method can be applied to the electronic system 1 to eliminate the mismatch between the modulation and demodulation frequencies.
[0027] In step S40, receiver 100 may be configured to demodulate the writing signal WS received from active pen 11 at a demodulation frequency. Specifically, active pen 11 is configured to modulate the writing signal WS at a modulation frequency, therefore receiver 100 is configured to demodulate the writing signal WS to identify whether the writing signal WS was transmitted by active pen 11.
[0028] In step S41, the processor 101 is configured to determine whether the demodulated writing signal DWS is abnormal. If the processor determines that the demodulated writing signal DWS is abnormal, the control method proceeds to step S42. Otherwise, it proceeds to step S43.
[0029] Specifically, receiver 100 is configured to demodulate the writing signal WS and provide the demodulated writing signal DWS to processor 101. In some embodiments, processor 101 may be configured to evaluate whether the demodulated writing signal DWS is abnormal based on a contact signal provided by active pen 11. Specifically, active pen 11 may be equipped with a pressure sensor to sense the pressure of the pen tip, thereby generating a contact signal to touch panel 10, indicating whether active pen 11 is actually contacting touch panel 10. Thus, processor 101 may be configured to use the contact signal to evaluate whether the demodulated writing signal DWS is abnormal.
[0030] In this embodiment, the processor 101 can be configured to determine whether a writing event has occurred by comparing the energy of the demodulated writing signal DWS with a threshold energy. When the energy of the demodulated writing signal DWS is greater than or equal to the threshold energy, the processor 101 can be configured to determine that a writing event is occurring, i.e., the active pen 11 is contacting the touch panel 10. Conversely, when the energy of the demodulated writing signal DWS is less than the threshold energy, the processor 101 can be configured to determine that a writing event has not occurred, and the active pen 11 is not contacting the touch panel 10.
[0031] To evaluate the demodulated writing signal (DWS), the processor 101 can be configured to compare the judgment of a writing event with the touch signal to see if the writing event is consistent with the touch signal. Specifically, when it is determined that a writing event is occurring and the touch signal also indicates that the active pen 11 is actually touching the touch panel 10, the processor 101 can be configured to determine that the demodulated writing signal (DWS) is normal. Conversely, when it is determined that a writing event has not occurred but the touch signal indicates that the active pen 11 is touching the touch panel 10, the processor 101 can be configured to determine that the demodulated writing signal (DWS) is abnormal. In other words, the touch signal can be used as a reference to verify whether the judgment of the writing event is correct, so as to reflect whether the demodulated writing signal (DWS) is abnormal.
[0032] In step S42, in response to determining that the demodulated writing signal DWS is abnormal, the processor 101 may be configured to adjust the demodulation frequency to increase the energy of the demodulated writing signal DWS. In some embodiments, the abnormal demodulated writing signal DWS may have a low energy level due to a mismatch between the first frequency and the second frequency. The reduced energy level of the demodulated writing signal DWS causes the processor 101 to incorrectly determine a writing event. Thus, the processor 101 may be configured to adjust the demodulation frequency to match the modulation frequency and eliminate the mismatch between them.
[0033] Figure 5A shows a timing diagram of the touch panel 10 sensing the writing signal WS according to some embodiments of the present disclosure. In Figure 5A, multiple display frames DF1 to DF10 are arranged sequentially, and the touch panel 10 is configured to display a corresponding image in each display frame. In addition to the display frames DF1 to DF10, multiple stylus sensing frames SF1 to SF8 are inserted, with each stylus sensing frame inserted between two display frames. In each stylus sensing frame, the touch panel 10 is configured to sense the writing signal WS to perform a corresponding control operation.
[0034] As shown in Figure 5A, in the first stylus sensing frame SF1, the processor 101 can be configured to set the demodulation frequency to a first frequency value f1 for demodulation. If the processor 101 determines that the demodulation frequency needs to be adjusted, the processor 101 can apply a frequency offset df to the demodulation frequency in the stylus sensing frame SF2 and set the demodulation frequency to f1+df. Similarly, in subsequent stylus sensing frames SF3 to SF8, the processor 101 can iteratively apply a frequency offset df to the demodulation frequency in each stylus sensing frame to set the demodulation frequency to f1-df, f1+2df, f1-2df, f1+3df, f1-3df, and f1+4df. In this embodiment, the processor 101 can scan the demodulation frequency in both increasing and decreasing directions, starting from the first frequency value. In other embodiments, the adjustment process may differ. For example, the scan may only be performed in one direction, either increasing or decreasing, and starting from the minimum or maximum frequency. The scanning of the first frequency may continue until the demodulated writing signal (DWS) with the maximum energy is found. The first frequency can be set to the frequency at which the demodulated writing signal (DWS) with the maximum energy is demodulated in order to obtain a minimized mismatch between the first frequency and the second frequency.
[0035] Figure 5B shows a timing diagram of the touch panel 10 sensing a writing signal WS according to some embodiments of the present disclosure. Similar to Figure 5A, multiple display frames DF1 to DF10 are arranged sequentially, and each stylus sensing frame SF1 to SF8 is inserted between two display frames. The touch panel 10 is configured to display a corresponding image in each display frame, and to sense a writing signal and determine whether a writing event has occurred in each stylus sensing frame.
[0036] In this embodiment, the processor 101 can apply multiple modulation frequencies to the receiver 100 in each stylus sensing frame. For example, in FIG5B, the processor 101 can set a first frequency to f1-df, f1, f1+df, f1+2df in stylus sensing frame SF1, and set it to f1+3df, f1+4df, f1+5df, f1+6df, etc. in subsequent frames. The scanning of demodulation frequencies can be performed in the increasing or decreasing direction.
[0037] Figure 6A shows the energy spectrum of the demodulated writing signal (DWS) at different demodulation frequencies according to some embodiments of this disclosure. In Figure 6A, the vertical axis corresponds to the energy of the demodulated writing signal (DWS), and the horizontal axis corresponds to the frequency value set as the demodulation frequency. Specifically, in this embodiment, the modulation frequency of the active pen 11 is set to frequency value f2, and the demodulation frequency of the receiver 100 is set to frequency value f1. As shown in Figure 6A, when the demodulation frequency is set to the first frequency value f1, the energy of the demodulated writing signal (DWS) is lower than the energy when the demodulation frequency is set to the second frequency value f2. In some embodiments, the deviation between the first and second frequency values causes the processor 101 to adjust the demodulation frequency to increase the energy of the demodulated writing signal (DWS).
[0038] Figure 6B illustrates how the demodulation frequency is scanned according to some embodiments of this disclosure. As described in the relevant paragraph of Figure 5A, the demodulation frequency can be scanned in increasing and decreasing directions, starting from an initially set first frequency value f1. Once the demodulated writing signal DWS with maximum energy is detected, the demodulation frequency scanning process can be terminated.
[0039] In other embodiments, other algorithms for scanning the maximum energy of the demodulated writing signal (DWS) may also be employed. For example, exhaustive search, hill climbing, binary search, or any method using multi-point inference may be used to scan the maximum energy of the demodulated writing signal (DWS).
[0040] Figure 6C illustrates how the first frequency f1 is adjusted according to some embodiments of this disclosure. In this embodiment, after a demodulated writing signal DWS with maximum energy is found when it is set to be substantially equal to or close to the second frequency value f2, the processor 101 may be configured to control the receiver 100 to set the demodulation frequency accordingly to the second frequency value f2 to obtain a demodulated writing signal DWS with maximum energy.
[0041] Figure 6D illustrates how the second frequency f2 is adjusted according to some embodiments of this disclosure. In this embodiment, the processor 101 may also be configured to instruct the active pen 11 to adjust the modulation frequency, rather than the demodulation frequency. Specifically, after discovering a demodulated writing signal DWS with maximum energy when the demodulated writing signal DWS is set to be substantially equal to or close to the second frequency value f2, the processor 101 may determine that there is a mismatch between the modulation and demodulation frequencies. To adjust the modulation frequency, the processor 101 may be configured to send an adjustment request and a first frequency value f1 to the active pen 11, causing the active pen 11 to set the modulation frequency to the first frequency value f1. Thus, as shown in Figure 6D, the energy spectrum of the demodulated writing signal DWS may shift to the right and center on the first frequency value f1, allowing the receiver 100 to obtain the demodulated writing signal DWS with maximum energy. In some other embodiments, the processor 101 may also be configured to provide the active pen 11 with the frequency difference between the first frequency value f1 and the second frequency value f2, so that the active pen 11 can be configured to fine-tune the modulation frequency using the frequency difference.
[0042] In step S43, the processor 101 is configured to perform a control operation based on the determined writing event and the coordinate information of the point where the writing signal is received. Specifically, after verifying that the demodulated writing signal DWS is normal in step S41 or adjusting the demodulation frequency in step S42, the touch panel 10 can operate normally to execute the control operation indicated by the active pen 11. The processor 101 can be configured to perform corresponding operations based on the determined touch event and the coordinate information of the demodulated writing signal DWS.
[0043] In summary, the electronic system and control method disclosed herein can be used to determine whether a demodulated writing signal is abnormal due to a mismatch between the modulation and demodulation frequencies. Appropriate adjustments can be made to match the modulation and demodulation frequencies, thereby increasing the energy level of the demodulated writing signal and thus improving the accuracy and sensitivity of touch control from the active pen.
[0044] Various modifications and variations can be made to the disclosed embodiments by those skilled in the art without departing from the scope or spirit of this disclosure. In view of the foregoing, this disclosure is intended to cover modifications and variations falling within the scope of the following claims and their equivalents.
Claims
1. A control method for enabling a touch panel to receive control from an active pen, characterized in that, The control method includes: using a demodulation frequency to demodulate a writing signal received from the active pen; determining whether the demodulated writing signal is abnormal; and in response to determining that the demodulated writing signal is abnormal, adjusting the demodulation frequency to increase the energy of the demodulated writing signal.
2. The control method according to claim 1, wherein the writing signal is modulated by a modulation frequency, and in response to determining that the demodulated writing signal is abnormal, the demodulation frequency is adjusted to substantially match or approach the modulation frequency.
3. The control method according to claim 1, wherein the energy of the demodulated writing signal is compared with a threshold energy, and when the energy of the demodulated writing signal is greater than or equal to the threshold energy, it is determined that a writing event is occurring, the writing event indicating that the active pen is touching the touch panel.
4. The control method according to claim 3, comprising: Receives a contact signal provided by the active pen, the contact signal indicating whether the active pen touches the touch panel; And determine whether the demodulated writing signal is abnormal based on the contact signal.
5. The control method according to claim 4, wherein when the energy of the demodulated writing signal is less than the threshold but the contact signal indicates that the active pen touches the touch panel, the demodulated writing signal is determined to be abnormal.
6. The control method according to claim 3, wherein the demodulation frequency is adjusted to a frequency that gives the demodulated writing signal maximum energy.
7. The control method according to claim 3, wherein the demodulation frequency is adjusted using an exhaustive search method, a ramping method, a binary search method, or a multi-point inference method.
8. The control method according to claim 1, wherein during the stylus sensing frame time, the first frequency is set to one or more test frequencies to demodulate the writing signal.
9. A touch panel adapted to receive control from an active pen, characterized in that, The touch panel includes: a receiver configured to: demodulate a writing signal received from the active pen using a demodulation frequency; and a processor coupled to the receiver and configured to: determine whether the demodulated writing signal is abnormal; and in response to determining that the demodulated writing signal is abnormal, adjust the demodulation frequency to increase the energy of the demodulated writing signal.
10. The touch panel of claim 9, wherein the writing signal is modulated at a modulation frequency, and in response to determining that the demodulated writing signal is abnormal, the processor is configured to adjust the demodulation frequency to substantially match or approach the modulation frequency.
11. The touch panel of claim 9, wherein the processor is configured to: compare the energy of the demodulated writing signal with a threshold energy, and when the energy of the demodulated writing signal is greater than or equal to the threshold energy, the processor is configured to determine a writing event and indicate that the active pen is contacting the touch panel.
12. The touch panel according to claim 11, wherein the processor is configured to: receive a contact signal provided by the active pen through the receiver, indicating whether the active pen contacts the touch panel; and determine whether the demodulated writing signal is abnormal based on the contact signal.
13. The touch panel of claim 12, wherein when the energy of the demodulated writing signal is less than the threshold but the contact signal indicates that the active pen is in contact with the touch panel, the processor is configured to determine that the demodulated writing signal is abnormal.
14. The touch panel of claim 11, wherein the processor is configured to adjust the demodulation frequency to a frequency at which the demodulated writing signal has maximum energy.
15. The touch panel of claim 11, wherein the processor is configured to adjust the demodulation frequency using exhaustive search, ramping search, binary search, or multi-point inference.
16. The touch panel of claim 9, wherein the processor is configured to set a first frequency to one or more test frequencies to demodulate the writing signal during the stylus sensing frame time.