CN116301408A - An Active Pen Synchronization Method and Device Based on Manchester Coding - Google Patents

Abstract

The invention relates to a Manchester-code-based active pen synchronization method and device, which comprises a touch screen and an active pen, wherein the touch screen comprises a conductive screen body, a driving unit and a modulation unit; the modulation unit converts the transmitted synchronous code into an uplink synchronous code in a Manchester coding mode; the driving unit converts the uplink synchronous code into a driving voltage waveform, and continuously changes the potential of the conductive screen body, so that the potential of the conductive screen body is changed along with the time transmission; the active pen amplifies and samples the signal received from the touch screen to obtain a digital signal sequence, and simultaneously captures the synchronization time of the uplink signal and acquires the clock information in the uplink signal to realize synchronization. The invention uses Manchester code as the uplink synchronous code of the active pen, and compared with the traditional active pen NRZ code, each subcode has at least one level inversion, the inversion times of unit time are more, the energy of the uplink signal is more, and the synchronous success rate of uplink communication can be improved.

Description

An Active Pen Synchronization Method and Device Based on Manchester Coding

technical field

The invention relates to the technical field of smart devices, in particular, an active pen synchronization method and device based on Manchester coding.

Background technique

At present, the capacitive active pen relies on the upstream signal of the capacitive touch screen for clock synchronization, but the traditional synchronization scheme is based on NRZ digital coding, and the anti-noise performance is average, and the traditional scheme requires both the active pen and the touch screen to carry high-precision clocks. Both the performance of the active pen and the board-level design have adverse effects, which increases the cost of the active pen.

It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the prior art, provide an active pen synchronization method and device based on Manchester coding, and solve the problems existing in the clock synchronization of the existing capacitive active pen.

The object of the present invention is achieved through the following technical solutions: a kind of active pen synchronizing device based on Manchester coding, it comprises touch screen and active pen, when described active pen clicks on touch screen, forms capacitance to carry out signal with touch screen the transmission of

The touch screen includes a conductive screen body, a drive unit and a modulation unit; the output end of the modulation unit is connected to the drive unit, the output end of the drive unit is connected to the conductive screen body, and the modulation unit converts the synchronous code sent into Uplink synchronous encoding in the form of Manchester encoding; the drive unit converts the uplink synchronous encoding into a driving voltage waveform, constantly changing the potential of the conductive screen, so that the potential of the conductive screen changes with time;

The active pen amplifies and samples the signal received from the touch screen to obtain a digital signal sequence, and at the same time captures the synchronization timing of the uplink signal and acquires clock information in the uplink signal to achieve synchronization.

The synchronous pen includes a receiving electrode, a receiving circuit unit, an amplifying circuit unit, a sampling unit and a processing unit; the receiving electrode forms a capacitor when it contacts the conductive screen body of the touch screen, and the potential change of the conductive screen body forms an uplink signal through the capacitor The receiving electrode transmitted to the active pen forms a small signal; the small signal received by the receiving circuit unit from the receiving electrode is amplified by the amplifying circuit unit, and the amplified signal is collected by the sampling unit to obtain a digital signal sequence and sent to the processing unit; the processing unit obtains the attribute Correlation detection processing is performed after the signal sequence to capture the synchronization timing of the uplink signal, and time interval capture processing is used to acquire clock information in the uplink signal to achieve synchronization.

The uplink synchronization code is composed of N subcodes, each subcode has the same duration, and each subcode includes the same high level and low level forms between the durations, and there are two high and low levels between two adjacent subcodes. The potential transition edge of the level transition, and the distance between the two potential transition edges is T.

An active pen synchronization method based on Manchester encoding, the synchronization method comprising:

The modulation unit converts the transmitted synchronous code into an upstream synchronous code in the form of Manchester code, and the drive unit converts the upstream synchronous code into a driving voltage waveform, constantly changing the potential of the conductive screen, so that the potential of the conductive screen changes with time;

The receiving electrode touches the conductive screen and forms a capacitance with the conductive screen, and the potential change of the conductive screen forms an uplink signal that is transmitted to the receiving electrode to form a small signal;

The receiving circuit unit receives the small signal and amplifies the small signal through the amplifying circuit unit, and obtains a digital signal sequence after being collected by the sampling unit;

The signal processing unit simultaneously performs correlation detection on the obtained digital signal sequence to capture the synchronization timing of the uplink signal, and captures and processes the time interval to acquire clock information in the uplink signal to achieve synchronization.

The specific steps of the related detection are as follows:

A1. Obtain a new digital signal value from the sampling unit, put the value into the detected queue, and remove the value that first entered the queue from the queue;

A2. Use a set of standard data queues to multiply the values in the detected queue one by one, and add all the multiplied values to obtain a related detection result of the detected queue;

A3. Judge the obtained correlation detection result with the preset threshold value. If the correlation detection result is greater than the threshold value, it is determined that a synchronized uplink signal has been captured. This moment is the synchronization time. If the correlation detection result is smaller than the threshold value, it is determined that it has not been captured. success.

The time interval capture includes the following steps:

B1. Obtain the clock edge position, that is, after modulation is Manchester encoding, an additional clock edge position is generated at the midpoint of each subcode;

B2. Calculate the time interval, and take the average value of the time interval to obtain the average time interval T2;

B3. Adjust the local clock of the active pen. If the current clock frequency of the active pen is F_pen, calculate the error between the average time interval T2 and T, and adjust the clock of the active pen to F_pen*T2/T of the current clock cycle, so that the active pen The clock is synchronized with the clock of the touch screen in real time;

B4. Repeat step B1 to restart the next synchronous action.

The present invention has the following advantages: an active pen synchronization method and device based on Manchester encoding, the digital waveform is modulated into Manchester encoding through the modulation unit, and the Manchester encoding with its own clock information is sent to the active pen through the conductive screen instead of The digital waveform is directly sent to the active pen through the conductive screen; the Manchester code is used as the upstream synchronization code of the active pen. Compared with the traditional NRZ code of the active pen, each subcode has at least one level inversion, and the number of inversions per unit time is more More, the energy of the uplink signal is greater, which can improve the synchronization success rate of uplink communication; based on Manchester coding, a code with clock information can be used to recover the clock directly from the uplink signal, so that the active pen no longer needs a high-precision clock. The complexity of the active pen solution and the comprehensive cost of the active pen can be reduced.

Description of drawings

Fig. 1 is the structural representation of device of the present invention;

2 is a schematic structural diagram of a touch screen;

Fig. 3 is a schematic diagram of coded modulation;

Fig. 4 is a schematic structural diagram of the active pen;

Fig. 5 is the schematic diagram of relevant detection;

Fig. 6 is a schematic flow chart of related detection;

Figure 7 is a schematic flow chart of time interval capture;

Figure 8 is a schematic diagram of time interval capture.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the application provided in conjunction with the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application. The present invention will be further described below in conjunction with the accompanying drawings.

In the application of the capacitive active pen, the present invention uses Manchester encoding as the encoding of the uplink signal. Through the coding design of this scheme, the signal strength per unit time of the uplink signal can be enhanced, the reliability of uplink reception can be enhanced, and the recognition rate of the uplink signal of the active pen can be improved; at the same time, the active pen can recover the clock from the uplink signal, so that the active pen no longer depends on High-precision clock reduces solution cost.

As shown in FIG. 1 and FIG. 2 , the capacitive touch screen includes a driving circuit unit, a conductive screen body, and a modulation unit. The modulating unit is connected with the conductive screen through the driving unit. As shown in FIG. 3 , the modulation unit converts the synchronous code to be sent (the original code 1011 in FIG. 3 ) into an uplink synchronous code in the form of Manchester code (if the modulated code in FIG. 3 ).

Compared with the original code, the number of signal inversion points of the modulated encoded signal is significantly increased. As shown in Figure 3, the number of inversions of the waveform level increases from 4 times to 6 times. More reversal points can generate more uplink signal energy, which can significantly improve subsequent synchronization capture. The driving unit converts the uplink synchronous code into a driving voltage waveform, and continuously changes the potential of the conductive screen, so that the potential of the conductive screen changes with time.

Further, the elements that the uplink synchronous encoding satisfies include: 1. A section of driving waveform is completed by a certain number (N) of subcode combinations; 1≤N≤1000; 2. The duration of each subcode is the same; The value range is 0.5us less than or equal to T less than or equal to 2us; 3. Each subcode has only two forms, from high level to low level, or from low level to high level, and low level and high level The flat durations each account for 50%; 4. Define the potential change as a potential transition edge; two potential transition edges must be found between two adjacent subcodes, and the distance between these two potential transition edges is recorded as T.

Wherein, the fourth property guarantees that the uplink encoding of the present invention has this property: there must be a potential transition edge every T time. Each subcode represents a data bit, and the subcode that changes from low level to high level is defined as data "1", and then the subcode that changes from high level to low level is defined as data "0".

As shown in Figure 4, the active pen mainly includes a receiving electrode, a receiving circuit unit, a sampling unit and a processing unit. The receiving electrode is connected with the circuit unit, and the receiving electrode is made of conductive material. A capacitor is formed between the receiving electrode and the conductive screen body of the touch screen, and the potential change of the conductive screen body forms an uplink signal, which is transmitted to the receiving electrode of the active pen through the capacitor to form a small signal. The receiving circuit unit amplifies the small signal collected by the receiving electrode through the amplifying circuit. The amplified signal is collected by the sampling unit to obtain a digital signal sequence. After the digital signal processing unit obtains the digital signal sequence, it will simultaneously perform two kinds of signal processing: correlation detection and time interval capture. The correlation detection is used to capture the synchronization timing of the uplink signal, and the time interval capture is used to acquire the clock information in the uplink signal.

Further, as shown in Figure 5 and Figure 6, the steps of related detection are as follows:

Step (1) Obtain a new digital signal value, put the value into the detected queue, and remove the value that first entered the queue from the queue;

Step (2) Use a set of standard data queues to multiply the values in the detected queue one by one, and add all the multiplied values to obtain a related detection result of the detected queue. The standard data queue is a set of Manchester coded sequences consisting of "+1", "0", and "-1".

Step (3) judges the correlation detection result obtained in step (2) and the preset threshold, and if the correlation detection result is greater than the threshold, it is determined that a synchronized uplink signal has been captured, and this moment is the synchronization moment. If the relevant detection result is less than the threshold, it is judged as unsuccessful capture.

In Figure 5, taking the 4-bit subcode as an example, the 4 subcodes are sampled to obtain 8 values and put them into the detected queue. The reference queue is also composed of 8 values, which is a pre-designed queue. When a sampling value is generated, a new detected queue is obtained, and 8 products are obtained by multiplying the detected queue and the reference queue one by one, and the 8 products are added together to obtain the final correlation detection result. Due to the autocorrelation of the code, only when the detected sequence is a known 4-bit subcode is completely aligned, the value of the correlation detection result will have a peak value. If the correlation detection result obtained at time t0 is 6, which is greater than the preset threshold, it is determined that the uplink signal has been successfully captured at time t0. When not completely aligned (as shown in FIG. 5 , the correlation detection results at time t0+T/2 and time t0-T/2 are much smaller than the correlation detection results at time t0.

Further, as shown in Figure 7 and Figure 8, the steps of time interval capture are as follows:

Step (1) Get the clock edge position. The position of the capture clock, that is, the midpoint of each subcode, that is, after modulation into Manchester encoding, an extra clock edge will be generated at the midpoint of each subcode.

Step (2) calculates time intervals, such as T2_0, T2_1, and T2_2 in FIG. 8 . The time intervals are averaged to obtain the average time interval T2.

Step (3) Adjust the local clock of the active pen. Assuming that the current clock frequency of the active pen is F_pen, through the error of T2 and T, the clock of the active pen is adjusted to F_pen*T2/T of the current clock cycle, so that the clock of the active pen and the clock of the touch screen are synchronized in real time.

Step (4) returns to step (1) to restart the next synchronous action.

The above descriptions are only preferred embodiments of the present invention, and it should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and Modifications can be made within the scope of the ideas described herein, by virtue of the above teachings or skill or knowledge in the relevant art. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Claims (6)

1. An initiative pen synchronizer based on Manchester code, its characterized in that: the touch screen comprises a touch screen and an active pen, wherein a capacitor is formed between the active pen and the touch screen for transmitting signals when the active pen clicks the touch screen;

the touch screen comprises a conductive screen body, a driving unit and a modulating unit; the output end of the modulation unit is connected with the driving unit, the output end of the driving unit is connected with the conductive screen body, and the modulation unit converts the transmitted synchronous code into an uplink synchronous code in a Manchester coding form; the driving unit converts the uplink synchronous code into a driving voltage waveform, and continuously changes the potential of the conductive screen body, so that the potential of the conductive screen body is changed along with the time transmission;

the active pen amplifies and samples the signals received from the touch screen to obtain a digital signal sequence, and simultaneously captures the synchronization time of the uplink signals and acquires the clock information in the uplink signals to realize synchronization.

2. The active pen synchronization device based on manchester encoding of claim 1, wherein: the synchronous pen comprises a receiving electrode, a receiving circuit unit, an amplifying circuit unit, a sampling unit and a processing unit; the receiving electrode forms a capacitor when contacting with a conductive screen body of the touch screen, the potential change of the conductive screen body forms an uplink signal, and the uplink signal is transmitted to the receiving electrode of the driving pen through the capacitor to form a small signal; the receiving circuit unit amplifies the small signals received by the receiving electrode through the amplifying circuit unit, and the amplified signals are acquired by the sampling unit to obtain digital signal sequences and then sent to the processing unit; and the processing unit acquires the attribute signal sequence, then carries out correlation detection processing for capturing the synchronization time of the uplink signal, and acquires the clock information in the uplink signal through time interval capturing processing to realize synchronization.

3. The active pen synchronization device based on manchester encoding of claim 1, wherein: the uplink synchronous code consists of N sub-codes, the duration of each sub-code is the same, each sub-code comprises two forms of high level and low level which are the same between the durations, two potential jump edges for high and low level conversion exist between two adjacent sub-codes, and the distance between the two potential jump edges is T.

4. An active pen synchronization method based on Manchester encoding is characterized by comprising the following steps: the synchronization method comprises the following steps:

the modulation unit converts the transmitted synchronous code into an uplink synchronous code in a Manchester coding mode, and the driving unit converts the uplink synchronous code into a driving voltage waveform to continuously change the potential of the conductive screen body, so that the potential of the conductive screen body is changed along with the time transmission;

the receiving electrode touches the conductive screen body and forms a capacitor with the conductive screen body, and the potential change of the conductive screen body forms an uplink signal which is transmitted to the receiving electrode to form a small signal;

the receiving circuit unit receives the small signals, amplifies the small signals through the amplifying circuit unit and acquires the small signals through the sampling unit to obtain a digital signal sequence;

and the signal processing unit carries out correlation detection on the obtained digital signal sequence at the same time to capture the synchronous time of the uplink signal, and the time interval capture process obtains the clock information in the uplink signal to realize synchronization.

5. The active pen synchronization method based on manchester encoding according to claim 4, wherein: the specific steps of the correlation detection are as follows:

a1, acquiring a new digital signal value from a sampling unit, putting the value into a detected queue, and removing the value which enters the queue first from the queue;

a2, multiplying the values in the detected queue one by using a group of standard data queues, and adding all the multiplied values to obtain a related detection result of the detected queue;

a3, judging the obtained related detection result and a preset threshold value, if the related detection result is larger than the threshold value, judging that the synchronous uplink signal is captured, wherein the moment is the synchronous moment, and if the related detection result is smaller than the threshold value, judging that the capturing is unsuccessful.

6. The active pen synchronization method based on manchester encoding according to claim 4, wherein: the time interval acquisition comprises the steps of:

b1, acquiring clock edge positions, namely generating additional clock edge positions at the middle point of each subcode after modulation into Manchester coding;

b2, calculating a time interval, and averaging the time interval to obtain an average time interval T2;

b3, adjusting the local clock of the active pen, if the clock frequency of the current active pen is F_pen, calculating the error of the average time interval T2 and T, and adjusting the clock of the active pen to F_pen T2/T of the current clock period, so that the clock of the active pen and the clock of the touch screen are synchronized in real time;

and B4, repeating the step B1 to restart the next synchronous operation.

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