TWI627563B - Active stylus and control method thereof - Google Patents

Abstract

The invention provides an active stylus and a control method thereof, which are suitable for a touch panel. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes, each driving electrode is configured to send a panel driving signal, and the sensing electrode is configured to receive the panel driving signal. The active stylus includes a receiving component for receiving the panel driving signal, a sensing module for deriving the signal characteristic of the panel driving signal, a signal generator for generating the analog driving signal, and a driving component for transmitting the analog driving signal and A control unit. The control unit generates an analog driving signal synchronized with and in phase with the panel driving signal through the signal generator according to the signal characteristic of the panel driving signal. In this way, in the mutual capacity mode, the touch panel can achieve multi-touch and distinguish the function of the hand and the active stylus.

Description

Active stylus and control method thereof

The invention relates to a stylus, in particular to an active stylus.

At present, the mainstream capacitive touch panel is a mutual-capacitive structure. The touch panel is usually provided with a plurality of driving electrodes and a plurality of sensing electrodes, and the driving and sensing electrodes are vertically staggered. The sensing capacitor is formed at the junction of the driving and sensing electrodes. When a finger touches the touch panel, the corresponding sensing capacitor changes, and the touch panel can obtain the touch position of the finger.

On the other hand, the stylus is commonly used as an auxiliary tool to assist users in writing or painting on the touch panel. The stylus on the market can be roughly classified into two types: passive and active. The main difference is that the active stylus can send the driving signal for sensing electrode sensing of the touch panel, but the passive stylus does not send the driver. Signal. However, the existing active stylus usually sends a driving signal of an analog finger, so that the sensing capacitance in the touch panel changes, but the control panel of the touch panel cannot distinguish the difference of the active stylus or the hand contact. Although the manufacturer has introduced a touch panel with a switchable mode, when the touch panel is in a self-contained mode (all electrodes (including drive electrodes) are switched to sense electrodes), the control chip can distinguish the active stylus Or the difference in hand contact, but this touch panel can only support single touch. Therefore, it can be known that how to provide an active stylus to enable the touch panel to achieve multiple touches and distinguish hand touch functions is one of the goals of the related industry.

In view of the above, an object of the present invention is to provide an active stylus and a control method thereof, so that a touch panel can distinguish that the touch of the active stylus and the hand can also support multi-touch.

To achieve the above object, the present invention provides an active stylus suitable for use in a touch panel. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes, each of the driving electrodes is configured to send a panel driving signal, and the sensing electrodes are configured to receive the panel driving signal. The active stylus includes a receiving component, a sensing module, a signal generator, a driving component and a control unit. The receiving component is configured to receive the panel driving signal. The sensing module is coupled to the receiving component and configured to react to the panel driving signal to obtain a signal characteristic of the panel driving signal. The signal generator is used to generate an analog drive signal. The driving component is coupled to the signal generator and configured to send the analog driving signal. The control unit is coupled to the sensing module and the signal generator, and generates the analog driving signal synchronized with and in phase with the panel driving signal through the signal generator according to the signal characteristic of the panel driving signal.

The present invention further provides a method for controlling an active stylus. The active stylus is applicable to a touch panel. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes, and the driving electrodes are used for each of the driving electrodes. Sending a panel driving signal, the sensing electrodes are configured to receive the panel driving signal, and the control method comprises the following steps. Receive the panel drive signal. Get the signal characteristics of the panel drive signal. The analog driving signal synchronized with the panel driving signal and in phase is generated according to the signal characteristic of the panel driving signal. Send the analog drive signal.

Since the sensing signals sensed by the sensing electrodes are opposite to the panel driving signals, when the finger contacts the active stylus, the corresponding sensing electrodes will sense different phases. Sensing the value to distinguish the finger or the active stylus. In addition, the touch The panel can be maintained in the mutual capacitance mode (without switching the drive electrodes to the sensing electrodes) to achieve most of the input control of the active stylus.

1‧‧‧Active stylus

5‧‧‧Hand

10‧‧‧ receiving components

20‧‧‧Sensor module

21‧‧‧Capacitive sensor

23‧‧‧Amplification circuit

30‧‧‧Signal Generator

40‧‧‧Drive components

50‧‧‧Control unit

51,53‧‧‧Signal strength

60‧‧‧ touch panel

61‧‧‧ drive electrode

63‧‧‧Induction electrodes

S31~S37‧‧‧Steps

A1, A2, A3‧‧‧ amplitude values

D‧‧‧duty cycle

F‧‧‧frequency

SC‧‧‧Control signal

SD‧‧‧ analog drive signal

SO‧‧‧ output signal

SP‧‧‧ panel driver signal

SS‧‧‧ signal strength

1 is a block diagram of components of an active stylus in accordance with a preferred embodiment of the present invention.

Figure 2 is a schematic diagram of a touch panel.

3 is a flow chart of a method of controlling an active stylus according to a preferred embodiment of the present invention.

Fig. 4A is an example of a waveform diagram of a panel driving signal transmitted by a driving electrode.

Figure 4B is an example of a waveform diagram of the signal strength sensed by the capacitive sensor.

Figure 4C is an example of a waveform diagram of an analog drive signal.

Figure 5 is a schematic diagram of writing and an example of a corresponding sensing waveform.

Please refer to FIG. 1 for an elementary block diagram of an active stylus 1 according to a preferred embodiment of the present invention. The active stylus 1 includes a receiving component 10, a sensing module 20, a signal generator 30, a driving component 40, and a control unit 50. The active stylus 1 is suitable for a capacitive touch panel 60. Referring to FIG. 2, the touch panel 60 includes a plurality of driving electrodes 61 and a plurality of sensing electrodes 63 interleaved with the driving electrodes 61. Each of the driving electrodes 61 is configured to transmit a panel driving signal SP, and the sensing electrodes 63 are configured to receive the panel driving signal SP.

It should be noted that the number of the driving and sensing electrodes 61, 63 shown in FIG. 2 is only for convenience of description. According to different design requirements, in other embodiments, the driving and sensing electrodes 61, 63 may have Different quantities.

The receiving component 10 can be any component made of a conductive material (eg, metal, metal oxide, graphene, etc.) that accepts (inducts) the panel driving signal SP. The receiving component 10 is configured to receive the panel driving signal SP.

The sensing module 20 is coupled to the receiving component 10 and configured to obtain signal characteristics (eg, signal strength, peak value, valley value, frequency, etc.) of the panel driving signal SP. The sensing module 20 includes a capacitive sensor 21 and an amplifying circuit 23 . The capacitive sensor 21 generates a corresponding signal strength SS (ie, an amplitude value or a sensed value) in response to the panel driving signal SP. The amplifying circuit 23 outputs an output signal SO in response to the panel driving signal SP. In the embodiment, the amplifying circuit 23 is a comparator, and the panel driving signal SP and a reference signal (related to the peak value of the panel driving signal SP) are input to the comparator, and if the panel drives the signal of the signal SP If the intensity is greater than the signal strength of the reference signal, the comparator outputs, for example, a high-potential output signal SO; otherwise, the comparator outputs a low-potential output signal SO.

It should be noted that the capacitive sensor 21 and the amplifying circuit 23 can be integrated into a module, a chip or a circuit according to different design requirements. However, in other embodiments, the two can be independent units.

The signal generator 30 can receive a control signal SC and generate a corresponding analog driving signal SD according to the control signal SC. The control signal SC is used to indicate the signal characteristic of the analog driving signal SD. In this embodiment, the signal characteristic of the analog driving signal SD includes at least one of a duty cycle and an amplitude value. And an analog timing information (eg, the start time point, period or frequency of each cycle, etc.).

The drive element 40 is an element made of the same or similar conductive material as the receiving element 10. The driving component 40 is coupled to the signal generator 30 and configured to transmit the analog driving signal SD.

The control unit 50 can be a microcontroller, a chip or other programmable general purpose or special purpose controller or the like or a combination of the above. The control unit 50 is coupled to the capacitive sensor 21 and the amplifying circuit 23 of the sensing module 20 and the signal generator 30. The control unit 50 can receive the signal strength SS and the output signal SO. The control unit 50 And having timing (such as built-in clock generator, oscillator, etc.), calculation, recording and the like to send the control signal SC to the signal generator 30.

The foregoing description is related to the component design of the active stylus 1. The control method of the active stylus 1 will be further described below with reference to FIGS. 3, 4A to 4C.

Please refer to FIG. 4A for an example of a waveform diagram of the panel driving signal SP sent by the driving electrode 61. The panel driving signal SP is a pulse signal having an amplitude value A1 and a frequency f. Please refer to FIG. 3 , and when the active stylus 1 is close to the touch panel 60 at a certain distance (for example, about 0.5 to 1 cm), the receiving component 10 can receive the panel driving signal SP. (Step S31).

In step S33, the sensing module 20 obtains the signal characteristic of the panel driving signal SP. Please refer to FIG. 4B for an example of a waveform diagram of the signal strength SS sensed by the capacitance sensor 21. The sensor sensor 21 senses a signal having an amplitude value A2 and a frequency f. The capacitive sensor 21 obtains the signal strength SS of the panel driving signal SP that it senses.

In this embodiment, after the control unit 50 obtains the signal strength SS of the panel driving signal SP, in order to reflect the distance between the active stylus 1 and the touch panel 60, the control unit 50 according to the signal strength SS Determine the signal characteristics of the analog drive signal SD. In this embodiment, the signal characteristic of the analog driving signal SD is a duty ratio D and an amplitude value A3. Please refer to the following table (1) for the signal characteristics of the analog drive signal SD: Table (1) The signal characteristic of the analog driving signal SD is also related to the signal intensity of the panel driving signal SP and the distance between the active stylus 1 and the touch panel 60. The signal strength of the panel drive signal SP changes. The product of the duty ratio D and the amplitude value A3 is related to the signal strength SS sensed by the capacitance sensor 21.

It should be noted that, in this embodiment, the pulse width and the pulse amplitude modulation PWM are used, and the PAM is only used for the description of the example. In other embodiments, the panel driving signal SP may have different signals according to the design requirements of different touch panels. Or the modulation mode code, and the analog driving signal SD needs to change with the signal characteristic of the panel driving signal SP.

On the other hand, the amplifying circuit 23 outputs an output signal SO according to the signal strength of the panel driving signal SP. The control unit 50 obtains two adjacent peaks of the panel driving signal SP according to the output signal SO of the amplifying circuit 23. For example, the control unit 50 determines that the output signal SO changes from a low potential to a high potential, and the control unit 50 And calculating the time difference of the two adjacent peaks to obtain the frequency (the reciprocal of the time difference is the frequency f of the panel driving signal SP). The control unit 50 can determine the analog timing information of the analog driving signal SD according to the panel timing information. In this embodiment, the panel driving signal The frequency f of the SP is equal to the frequency f of the analog drive signal SD. In addition, the control unit 50 can estimate the panel driving signal SP at the starting time point of each cycle to synchronize the panel driving signal SP with the analog driving signal SD.

It should be noted that there are many ways to calculate the signal frequency or period. For example, the amplifying circuit 23 is an operational amplifier, and the control unit 50 can obtain a peak value and an adjacent valley of the panel driving signal SP. The value may be derived from the time difference between the peak value and the valley value; or the control unit 50 calculates a time difference between the two adjacent valleys and the like.

In step S35, the control unit 50 according to the signal characteristic of the panel driving signal SP, and will indicate the signal characteristic of the analog driving signal SD (ie, frequency f, amplitude value A3, duty ratio D, each period) The control signal SC of the start time point is transmitted to the signal generator 30 to control the signal generator 30 to generate an analog driving signal SD synchronized with the panel driving signal SP (ie, the frequency and the starting time point) (eg, As shown in FIG. 4C, the signal generator 30 and the analog driving signal SD are in phase with the panel driving signal SP (see also FIGS. 4A and 4C). In step S37, the driving component 40 can transmit the analog driving signal SD.

Referring to FIG. 5 , when the first touch 5 is in contact with the touch panel 60 , the analog driving signal SD sent by the active stylus 1 is in phase with the panel driving signal SP, and the touch is The control panel 60 senses the negative signal strength 51; and the capacitance change caused by the hand 5 causes the touch panel 60 to sense a positive signal intensity 53 to distinguish the active stylus 1 And the touch of the hand 5. That is, in the mutual capacitive mode (ie, the driving electrodes still send the panel driving signal SP), the touch panel 60 can still recognize the active stylus 1 and the hand 5, thereby filtering the hand. The sensing signal of 5 is used to achieve the anti-touch writing function. In addition, in the mutual capacity mode, when two or more of the active touch When the pen 1 is close to the touch panel 60, the touch panel 60 can sequentially sense the change of the capacitance through the sensing electrodes 63, thereby obtaining the sensing position of the active stylus 1 without The ghost situation happened.

On the other hand, the signal characteristic of the analog driving signal SD is related to the signal strength SS obtained by the capacitive sensor 21 (ie, the distance between the active stylus 1 and the touch panel 60). The panel 60 can determine the distance between the active stylus 1 and the touch panel 60 according to the signal intensity sensed by the analog driving signal SD, thereby simulating the light stroke change or other stroke conditions. It should be noted that the control unit 50 can also fix the duty ratio D and the amplitude value A3 of the analog driving signal SD, and still achieve the functions of distinguishing the active stylus 1 and the hand 5 and the multi-touch. .

The above is only the description of the embodiments of the present invention, and is not intended to limit the scope of the present invention. Any simple structural retouching or variation that does not depart from the spirit of the present invention is still within the scope of the patent application scope of the present invention.

Claims (8)

An active stylus is applicable to a touch panel. The touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes. Each of the driving electrodes is configured to send a panel driving signal, and the sensing electrodes are configured to receive The active driving stylus includes: a receiving component for receiving the panel driving signal; a sensing module coupled to the receiving component, the sensing module configured to react to the panel Driving a signal to obtain a signal characteristic of the panel driving signal; a signal generator for generating an analog driving signal; a driving component coupled to the signal generator, the driving component for transmitting the analog driving signal; The control unit is coupled to the sensing module and the signal generator. The control unit generates the analog driving signal that is synchronized with the panel driving signal and is in phase with the panel driving signal according to the signal characteristic of the panel driving signal. The signal characteristic of the panel driving signal includes a signal strength, and the sensing module includes a capacitive sensor coupled to the receiving component and the control unit, Receiving sensor in response to the panel drive signal corresponding to the intensity of the signal derived, and the control unit determines signal characteristics of the analog driving signals according to the signal strength. The active stylus according to claim 1, wherein the analog driving signal is a pulse signal, and the signal characteristic of the analog driving signal includes at least one of a duty ratio and an amplitude value. The active stylus according to claim 1, wherein the signal characteristic of the panel driving signal includes panel timing information, and the signal characteristic of the analog driving signal includes analog timing information, and the sensing module includes an amplifying circuit coupling. Connected to the receiving component and the control unit, the amplifying circuit outputs an output signal in response to the panel driving signal, and the control unit obtains the output signal according to the output signal The panel timing information, and the control unit determines the analog timing information of the analog driving signal according to the panel timing information. The active stylus of claim 3, wherein the timing information is a frequency, and the control unit obtains two adjacent peaks of the panel driving signal according to the output signal, and the control unit calculates the two adjacent The time difference of the peaks is used to derive the frequency. An active stylus is applied to a touch panel, the touch panel includes a plurality of driving electrodes and a plurality of sensing electrodes, and each of the driving electrodes is configured to send a panel driving The signal is used to receive the panel driving signal, and the control method includes: receiving the panel driving signal, the signal characteristic of the panel driving signal includes a signal strength; and obtaining the signal characteristic of the panel driving signal, including reacting to The panel drives the signal to obtain a corresponding signal strength; and determines the signal characteristic of the analog driving signal according to the signal strength; and generates the analog driving signal synchronized with the panel driving signal according to the signal characteristic of the panel driving signal; And sending the analog drive signal. The control method of the active stylus according to claim 5, wherein the analog driving signal is a pulse signal, and the signal characteristic of the analog driving signal includes at least one of a duty ratio and an amplitude value. The control method of the active stylus according to claim 5, wherein the signal characteristic of the panel driving signal includes a panel timing information, and the signal characteristic of the analog driving signal includes an analog timing information, and the panel driving signal is obtained. The step of the signal characteristic includes: obtaining the panel timing information according to the panel driving signal; The analog timing information of the analog driving signal is determined according to the panel news information. The control method of the active stylus according to claim 7, wherein the timing information is a frequency, and the step of obtaining the panel timing information according to the panel driving signal comprises: determining two adjacent peaks of the panel driving signal And calculating the time difference of the two adjacent peaks to derive the frequency.