Digital electromagnetic pen, input system and control method thereof

Abstract

The present invention provides a digital electromagnetic pen, comprising a single chip unit, a transmitting control unit and a transmitting and receiving unit connected in sequence, a first rectifying and filtering unit and a second rectifying and filtering unit connected in parallel between the single chip unit and the transmitting and receiving unit, and a pressure and key detection unit connected to the single chip unit, wherein the transmitting and receiving unit receives the electromagnetic signal transmitted by the digital tablet and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit; the first rectifying and filtering unit outputs the electrical signal to the single chip unit after shaping and filtering; the second rectifying and filtering unit outputs the electrical signal to the single chip unit after shaping and filtering to wake up the single chip unit; the pressure and key detection unit detects the pen tip pressure data and key state; the single chip unit controls the length of the closing time of the transmitting and controlling unit according to the detection result. At the same time, the present invention also provides an input system and a control method thereof.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic pens, and in particular relates to a digital electromagnetic pen, an input system and a control method thereof. Background Art

[0002] Electromagnetic handwriting pens have long been known to people. Their main purpose is to replace human fingers as input devices on drawing boards, drawing screens, signature boards, handwriting tablets, handwriting notebooks or mobile phones. Existing electromagnetic handwriting pens are divided into active pens and passive pens. Active pens require batteries to provide power sources for operation, while passive pens obtain power from induction on the electromagnetic board. Passive pens have become mainstream products. Passive electromagnetic pens are divided into analog and digital types. Analog types rely on changing frequency or phase to transmit key and pressure signals to the digital board, such as US Patent US5600105. Therefore, a larger bandwidth is required to cover the frequency conversion range, which makes it easy for unexpected frequencies (noise) to affect the stability of pressure and coordinates. Digital types use fixed frequency amplitude modulation mode to transmit key and pressure signals to the digital board, such as US Patents US5969296 and US5977959. Therefore, a longer power-on time and count are required to obtain a higher pressure level, which consumes more electricity.

[0003] In order to satisfy the user's use quality, design manufacturers often try to increase the pressure level as much as possible. Once the pressure level is increased, the signal transmission rate must be sacrificed. For example, in US Pat. No. 5,977,959, every time the pressure doubles, the time for transmitting and receiving one bit must be increased (about 200us). For example, for 1023-level pressure, 10 bits need about 2000us. In addition, Taiwan Patent TW451155 discloses a digitizer coordinate input system. The electromagnetic wave of a fixed frequency emitted by the digital tablet end is converted into a pressure signal through the pressure sensor at the electromagnetic pen end. For example, if a 500KHz transmission frequency is used to obtain 1024-level pressure, 1024*1 / 500KHz=2048us must be used. If a higher pressure level is to be obtained, such as 8192-level pressure, 8192*1 / 500KHz=16384us is required.

[0004] Therefore, it is necessary to provide a new digital electromagnetic pen to solve the above problem. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a digital electromagnetic pen, an input system and a control method thereof.

[0006] A digital electromagnetic pen comprises a single chip unit, a transmitting control unit and a transmitting and receiving unit connected in sequence, a first rectifying and filtering unit and a second rectifying and filtering unit connected in parallel between the single chip unit and the transmitting and receiving unit, and a pressure and key detection unit connected to the single chip unit, wherein:

[0007] The transmitting and receiving unit receives the electromagnetic signal transmitted by the digitizer and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonance frequency and sends the resonance signal to the digitizer, so that the digitizer acquires the touch information of the electromagnetic pen;

[0008] The first rectifying and filtering unit shapes and filters the electrical signal output by the transmitting and receiving unit and then outputs it to the single chip unit to provide power for it;

[0009] The second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs the signal to the single-chip unit to wake up the single-chip unit;

[0010] The pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen;

[0011] The single chip unit controls the length of time the transmitting control unit is turned off according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet.

[0012] Preferably, the single chip unit includes an ADC converter, a comparator, a time counter and a controller.

[0013] When the single-chip unit obtains power, it enters deep sleep after initialization. The comparator compares the voltage output by the second rectifier and filter unit with the preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. The interrupt signal wakes up the single-chip unit, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit. The controller controls the length of time the transmitting control unit is turned off according to the pen tip pressure data and button status, thereby controlling the energy intensity of the resonant signal sent by the transmitting and receiving unit to the digital tablet.

[0014] Preferably, the transmitting and receiving unit includes a winding coil and a capacitor connected in parallel.

[0015] Preferably, the transmitting control unit includes a field effect transistor and a diode, the source of the field effect transistor is respectively connected to the input end of the pressure and key detection unit and one end of the transmitting and receiving unit, the drain is connected to the cathode of the diode, the gate is connected to the single chip unit, and the anode of the diode is connected to the other end of the transmitting and receiving unit.

[0016] The present invention also provides an input system, comprising a digital electromagnetic pen and a digital tablet.

[0017] The digital electromagnetic pen comprises a single chip unit, a transmitting control unit and a transmitting and receiving unit connected in sequence, a first rectifying and filtering unit and a second rectifying and filtering unit connected in parallel between the single chip unit and the transmitting and receiving unit, and a pressure and key detection unit connected to the single chip unit.

[0018] The transmitting and receiving unit receives the electromagnetic signal transmitted by the digitizer and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonance frequency and sends the resonance signal to the digitizer, so that the digitizer acquires the touch information of the electromagnetic pen;

[0019] The first rectifying and filtering unit shapes and filters the electrical signal output by the transmitting and receiving unit and then outputs it to the single chip unit to provide power for it;

[0020] The second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs the signal to the single-chip unit to wake up the single-chip unit;

[0021] The pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen;

[0022] The single chip unit controls the duration of the shutdown time of the transmitting control unit according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet;

[0023] The digital tablet obtains touch information of the digital electromagnetic pen according to the resonance signal.

[0024] Preferably, the single chip unit includes an ADC converter, a comparator, a time counter and a controller.

[0025] When the single-chip unit obtains power, it enters deep sleep after initialization. The comparator compares the voltage output by the second rectifier and filter unit with the preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. The interrupt signal wakes up the ADC converter and the controller, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit. The controller controls the length of time the transmitting control unit is turned off according to the pen tip pressure data and button status, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet.

[0026] Preferably, the transmitting control unit includes a field effect transistor and a diode, the source of the field effect transistor is respectively connected to the input end of the pressure and key detection unit and one end of the transmitting and receiving unit, the drain is connected to the cathode of the diode, the gate is connected to the single chip unit, and the anode of the diode is connected to the other end of the transmitting and receiving unit.

[0027] The present invention also provides a control method for the input system as described above, which comprises the following steps:

[0028] Step S1, the digital tablet transmits a fixed-frequency electromagnetic signal of a set duration;

[0029] Step S2, when the digital electromagnetic pen is within the detection range of the digital tablet, the transmitting and receiving unit receives the electromagnetic signal emitted by the digital tablet and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonant frequency and sends the resonant signal to the digital tablet;

[0030] Step S3, the first rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit. After the single-chip unit obtains power, it enters deep sleep after initialization. Meanwhile, the second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit.

[0031] Step S4, the single chip unit compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison output, and determines whether to wake up the single chip unit according to the comparison result. If the single chip unit is awakened, step S5 is executed, otherwise the single chip unit returns to the main program and enters deep sleep;

[0032] Step S5, the pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen, and the single chip unit controls the length of the shutdown time of the transmitting control unit according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet;

[0033] Step S6, the digital tablet analyzes and restores the received resonance signal according to the energy indication beacon to obtain the touch information of the digital electromagnetic pen, wherein the energy indication beacon is the signal strength received by the transmitting and receiving unit when the transmitting control unit is turned off;

[0034] Repeat steps S2-S6 until the digital electromagnetic pen leaves the detection range of the digital tablet.

[0035] Preferably, the single chip unit includes an ADC converter, a comparator, a time counter and a controller.

[0036] When the single chip unit enters deep sleep after initialization, the time counter starts timing;

[0037] The comparator compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. If an interrupt signal is generated within a preset time, the interrupt signal wakes up the ADC converter and the controller, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and key status detected by the pressure and key detection unit. The controller controls the length of the shutdown time of the transmitting control unit according to the pen tip pressure data and key status, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet;

[0038] If no interrupt signal is generated within the preset time, the time counter overflows and generates an interrupt. If the comparator is disabled at this time, the time counter is reset to zero and the comparator is re-enabled, and the program returns to the main program and enters deep sleep. If the comparator is enabled at this time, the ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit and returns to the main program and enters deep sleep.

[0039] Preferably, in step S4, the single chip unit controls the duration of the closing time of the emission control unit according to the detection result of the pressure and key detection unit as follows:

[0040] If the key switch is not pressed and the pen tip is not under pressure, the emission control unit is turned off;

[0041] If it is detected that the button switch is pressed, the emission control unit will turn on, and if the detected pressure value is 0, the emission control unit will be turned off for the time period corresponding to the pressure value of 0, and if the detected pressure value is not 0, the emission control unit will perform a closing or opening operation according to the size of the pressure value and control the opening time according to the preset energy code.

[0042] Compared with the related art, the digital electromagnetic pen provided by the present invention has the following beneficial effects:

[0043] 1. High flexibility in using single chip;

[0044] 2. When the detected pressure is zero or the high-bit group is all zero, the comparator can be turned off and only the time counter is used to save power consumption by changing the counting time;

[0045] 3. Multiple bits of data are compressed into one transmission and reception time, which is faster and more energy-saving;

[0046] 4. Using ADC converter to read pressure is faster, does not need to rely on the frequency of the digital board transmission, and the circuit is more economical and simpler;

[0047] 5. Each time the energy indicator beacon is used as the energy reference, the signal analysis is more accurate and will not be affected by the working height of the electromagnetic pen. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0049] Figure 1 A structural block diagram of the digital electromagnetic pen provided by the present invention;

[0050] Figure 2 for Figure 1 The circuit schematic diagram of the digital electromagnetic pen shown;

[0051] Figure 3 A schematic flow chart of a control method for an input system provided by the present invention;

[0052] Figure 4 It is a schematic diagram of signal transmission between a digital electromagnetic pen and a digital tablet;

[0053] Figure 5 A schematic diagram of the energy intensity of the resonance signal between the digital electromagnetic pen and the digital tablet;

[0054] Figure 6 It is a schematic diagram of signal transmission when the digital electromagnetic pen is floating and the key switch is OFF;

[0055] Figure 7 It is a schematic diagram of signal transmission when the digital electromagnetic pen contacts the digital tablet and the key switch is ON;

[0056] Figure 8 Schematic diagram of amplitude modulation between a digital electromagnetic pen and a digital tablet. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] Please refer to the figure Figure 1 , is a structural block diagram of a digital electromagnetic pen provided by the present invention. The present invention provides a digital electromagnetic pen 100, which includes a single chip unit 1, a transmitting and receiving unit 2, a first rectifying and filtering unit 3, a second rectifying and filtering unit 4, a pressure and key detection unit 5 and a transmitting and controlling unit 6. The single chip unit 1, the transmitting and controlling unit 6 and the transmitting and receiving unit 2 are connected in sequence, and the first rectifying and filtering unit 3 and the second rectifying and filtering unit 4 are connected in parallel between the single chip unit 1 and the transmitting and receiving unit 2. The pressure and key detection unit 5 is connected to the single chip unit 1. Wherein:

[0059] The transmitting and receiving unit 2 receives the electromagnetic signal emitted by the digitizer and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit 3 and the second rectifying and filtering unit 4. When the frequency of the electromagnetic signal is close to its own resonant frequency, resonance is generated and the resonant signal is sent to the digitizer, so that the digitizer acquires the touch information of the electromagnetic pen.

[0060] The first rectifying and filtering unit 3 shapes and filters the electrical signal output by the transmitting and receiving unit 2 and then outputs it to the single chip unit 1 to provide power for it;

[0061] The second rectifying and filtering unit 4 performs shaping and filtering on the electrical signal output by the transmitting and receiving unit 2 and then outputs the signal to the single chip unit 1 to wake up the single chip unit 1;

[0062] The pressure and key detection unit 5 detects the pen tip pressure data and key status of the digital electromagnetic pen;

[0063] The single chip unit 1 controls the duration of the shutdown of the transmitting control unit 6 according to the detection result of the pressure and key detecting unit 5 , thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit 2 to the digital tablet.

[0064] Specifically, the single-chip unit 1 includes an ADC converter, a comparator, a time counter and a controller. When the single-chip unit obtains power, it enters deep sleep after initialization. The comparator compares the voltage output by the second rectifier and filter unit 4 with the preset comparison voltage to generate a comparison output. At the rising edge of the comparison output, an interrupt signal is generated. The interrupt signal wakes up the single-chip unit, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and key status detected by the pressure and key detection unit 5. The controller controls the length of the shutdown time of the transmitting control unit 6 according to the pen tip pressure data and key status, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit 1 to the digital tablet. The comparison voltage of the comparator is determined by the voltage contained in the single-chip unit 1, and the high and low can be controlled.

[0065] Please refer to Figure 2 The transmitting and receiving unit 2 includes a winding coil L1 and a capacitor C1 connected in parallel, and one end of the inductor L1 and the capacitor C1 is grounded. The operating frequency of the transmitting and receiving unit 2

[0066] The first rectifying and filtering unit 3 includes a capacitor C2, two diodes D1, a diode D2 and a capacitor C3, one end of the capacitor C2 is connected to the non-grounded end of the inductor L1, the positive electrode of one diode D1 is connected to the other end of the capacitor C2, and the negative electrode is connected to the input end of the single-chip unit; the negative electrode of another diode D1 is connected to the other end of the capacitor C2, and the positive electrode is connected to the grounding end of the capacitor C1 and the inductor L1; the diode D2 and the capacitor C3 are connected in parallel between the grounding end of the capacitor C1 and the inductor L1 and the input end of the single-chip unit, and the positive electrode of the diode D2 is connected to the grounding end of the inductor L1, and the negative electrode is connected to the input end of the single-chip unit.

[0067] The second rectifying and filtering unit 4 includes a capacitor C4, two diodes D3, a capacitor C5, a resistor R1 and a resistor R2, one end of the capacitor C4 is connected to the non-grounded end of the inductor L1 and the capacitor C1, the positive electrode of one diode D3 is connected to the other end of the capacitor C4, and the negative electrode is connected to the input end of the single-chip unit; the negative electrode of another diode D3 is connected to the other end of the capacitor C4, and the positive electrode is grounded; the capacitor C5 and the resistor R1 are connected in parallel between the positive electrode of the grounded diode D3 and the single-chip unit, and the capacitor C5, the resistor R1 and the negative electrode of the diode D3 are connected to the input end of the single-chip unit through the resistor R2.

[0068] The pressure and key detection unit 5 includes a fixed capacitor C6 and a pressure sensing capacitor C7 connected in series between the single chip unit 1 and the emission control unit 6, and a first switch S1 and a second switch S2 connected in parallel between the single chip unit 1 and the emission control unit 6. The connection point between the fixed capacitor C6 and the pressure sensing capacitor C7 is connected to the single chip unit through a wire.

[0069] The transmitting control unit 6 includes a field effect transistor Q1, a diode D4 and a resistor R3. The source of the field effect transistor Q1 is respectively connected to the input end of the pressure and key detection unit, the capacitor C1 and the ground end of the inductor L1, the drain is connected to the cathode of the diode D4, the gate is connected to the single chip unit and is connected to the source and the input end of the pressure and key detection unit through the resistor R3; the anode of the diode D4 is connected to the non-grounded end of the capacitor C1 and the inductor L1.

[0070] The present invention also provides an input system, which includes the digital electromagnetic pen 100 and a digital tablet as described above. The digital tablet is an existing structure, and the present invention does not limit the specific structure of the digital tablet. The structure of the digital electromagnetic pen 100 is as described above and will not be repeated. The digital tablet obtains its touch information according to the resonance signal emitted by the digital electromagnetic pen 100.

[0071] See also Figure 3 The present invention also provides a control method for the input system as described above, which comprises the following steps:

[0072] Step S1, the digital tablet transmits a fixed-frequency electromagnetic signal of a set duration;

[0073] Step S2, when the digital electromagnetic pen 100 is within the detection range of the digital tablet, the transmitting and receiving unit 2 receives the electromagnetic signal emitted by the digital tablet and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit 3 and the second rectifying and filtering unit 4, and generates resonance when the frequency of the electromagnetic signal is close to its own resonance frequency and sends the resonance signal to the digital tablet;

[0074] Step S3, the first rectifying and filtering unit 3 performs shaping and filtering on the electrical signal output by the transmitting and receiving unit 1 and then outputs it to the single-chip unit 1. After the single-chip unit 1 obtains power, it enters deep sleep after initialization. Meanwhile, the second rectifying and filtering unit 4 performs shaping and filtering on the electrical signal output by the transmitting and receiving unit 2 and then outputs it to the single-chip unit 1.

[0075] Step S4, the single-chip unit 1 compares the voltage output by the second rectifying and filtering unit 4 with a preset comparison voltage to generate a comparison output, and determines whether to wake up the single-chip unit 1 according to the comparison result. If the single-chip unit 1 is awakened, step S5 is executed, otherwise the single-chip unit 1 returns to the main program and enters deep sleep;

[0076] Specifically, the single chip unit 1 includes an ADC converter, a comparator, a time counter and a controller (MCU). When the single chip unit 1 enters deep sleep after initialization, the time counter starts timing; the comparator compares the voltage output by the second rectifier and filter unit 4 with a preset comparison voltage to generate a comparison output, and an interrupt signal is generated at the rising edge of the comparison output, such as Figure 4 As shown, if an interrupt signal is generated within a preset time, the interrupt signal wakes up the ADC converter and the controller, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and the key status detected by the pressure and key detection unit 5. The controller controls the length of the shutdown time of the transmitting control unit 6 according to the pen tip pressure data and the key status, and then controls the energy intensity of the resonant signal sent by the transmitting and receiving unit 2 to the digitizer. Each time an interrupt signal is generated on a rising edge, the time counter is reset to zero. The signal (synchronization / beacon) emitted by the digitizer starts a short time count (ST) after the interrupt is generated on the rising edge. If the interrupt is received within the short time count, the time counter is reset to zero. If no interrupt signal is received, the time counter overflows and generates an interrupt. If the comparator is disabled at this time, the time counter is reset to zero and the comparator is re-enabled before returning to the main program to enter deep sleep. If the comparator is enabled, the synchronization signal, pressure signal capture, and pen body button status are checked to prepare data, and then the program returns to the main program to enter deep sleep. After n rising edge interrupts, the long time count (LT) is started and the comparator is disabled until the long time count generates an interrupt, the comparator is enabled again, and the program returns to the main program to enter deep sleep. After a rising edge interrupt is generated, the short time count (ST) is started and the above steps are repeated until the electromagnetic pen leaves the detection range of the tablet.

[0077] Step S5, the pressure and key detection unit 5 detects the pen tip pressure data and key status of the digital electromagnetic pen, and the single chip unit 1 controls the length of the shutdown time of the transmitting control unit 6 according to the detection result of the pressure and key detection unit 5, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet;

[0078] See also Figure 5, which is a schematic diagram of the energy intensity of the resonance signal between the digital electromagnetic pen and the digitizer. The field effect tube Q1 of the transmitting control unit 6 is essentially a switching device. The length of time the field effect tube Q1 is closed directly affects the amount of energy received by the digitizer. The earlier the field effect tube Q1 is turned on, the smaller the energy received by the digitizer.

[0079] In this step, the single chip unit 1 controls the duration of the closing time of the emission control unit 6 according to the detection result of the pressure and key detection unit:

[0080] If the key switch is not pressed and the pen tip is not under pressure, the emission control unit is turned off, that is, the field effect tube Q1 is turned off during this period, and the field effect tube Q1 is also turned off during other periods; please refer to Figure 6 , which is a signal transmission diagram when the digital electromagnetic pen is floating and the key switch is OFF. At this time, since the electromagnetic pen is far away from the detection area of ​​the digital tablet and has the weakest power, the single-chip unit 1 is in a sleep state all the time except for reading the pen tip pressure data, key status and synchronization signal, thereby achieving the purpose of power saving.

[0081] If it is detected that the button switch is pressed, the emission control unit will turn on, and if the detected pressure value is 0, the emission control unit will be turned off for the time period corresponding to the pressure value of 0, and if the detected pressure value is not 0, the emission control unit will perform a closing or opening operation according to the size of the pressure value and control the opening time according to the preset energy code.

[0082] In this way, the field effect transistor Q1 switches between on and off, thereby controlling the length of time the emission control unit 6 is turned off, and further controlling the amount of energy received by the digital tablet.

[0083] See also Figure 7 , which is a signal transmission diagram when the digital electromagnetic pen contacts the digital tablet and the key switch is ON. At this time, since the electromagnetic pen is closer to the detection area of ​​the digital tablet, the maximum power consumption is allowed to be a little higher. Therefore, the single-chip unit 1 is in a sleep state all the time except for reading the pen tip pressure data, key status, transmitting pressure signals and synchronization signals.

[0084] In step S6, the digital tablet analyzes and restores the received resonance signal according to the energy indication beacon to obtain the touch information of the digital electromagnetic pen, wherein the energy indication beacon is the signal strength received by the transmitting and receiving unit 2 when the transmitting control unit is turned off 6.

[0085] When the transmitting control unit 6 is turned off, the signal strength received by the transmitting and receiving unit 2 is used as an energy indicator beacon, and the transmitting and receiving unit 2 transmits the energy indicator beacon to the digitizing board, and the digitizing board receives the energy indicator beacon and uses it as an energy reference to analyze and restore the resonance signal received. Since the digitizing board uses the energy indicator beacon as an energy reference each time, the signal analysis is more accurate and will not be affected by the working height of the electromagnetic pen.

[0086] See also Figure 8 , is a schematic diagram of amplitude modulation between a digital electromagnetic pen and a digital tablet. The digital tablet transmits and receives in the following order:

[0087] A. Emit a fixed-frequency electromagnetic signal of the first set duration. The first set duration is usually greater than 500us. The first 256us is for synchronization, and the last 256us is for ADC to capture pressure, read key status, and prepare to send back data.

[0088] B. Receive energy indication beacon;

[0089] C. transmitting a fixed-frequency electromagnetic signal of a second set duration, wherein the second set duration is usually less than 256us;

[0090] D. Receive the energy of pressure bit0 and bit1, and restore them according to the energy indicator beacon;

[0091] E. Repeat steps C and D until the pressure signal detection is completed;

[0092] F. transmitting a fixed-frequency electromagnetic signal of a second set duration, wherein the second set duration is usually less than 256us;

[0093] G. Receive energy;

[0094] H. Repeat steps F and G until the detection of the X-axis coordinate signal and the Y-axis coordinate signal is completed.

[0095] The energy intensity of the energy indicator beacon is set to 1, the signal energy intensity of 3 / 4 to 1 represents 00 (0), the signal energy intensity of 1 / 2 to 3 / 4 represents 01 (1), the signal energy intensity of 1 / 4 to 1 / 2 represents 10 (2), and the signal energy intensity of 0 to 1 / 4 represents 11 (3), as shown in Table 1. In this way, 8 transmit and receive combinations can represent 16 bits of data.

[0096] Table 1

[0097]

[0098]

[0099] Compared with the related art, the digital electromagnetic pen provided by the present invention has the following beneficial effects:

[0100] 1. High flexibility in using single chip;

[0101] 2. When the detected pressure is zero or the high-bit group is all zero, the comparator can be turned off and only the time counter is used to save power consumption by changing the counting time;

[0102] 3. Multiple bits of data are compressed into one transmission and reception time, which is faster and more energy-saving;

[0103] 4. Using ADC converter to read pressure is faster, does not need to rely on the frequency of the digital board transmission, and the circuit is more economical and simpler;

[0104] 5. Each time the energy indicator beacon is used as the energy reference, the signal analysis is more accurate and will not be affected by the working height of the electromagnetic pen.

[0105] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A digital electromagnetic pen, characterized in that: The invention comprises a single chip unit, a transmitting control unit and a transmitting and receiving unit connected in sequence, a first rectifying and filtering unit and a second rectifying and filtering unit connected in parallel between the single chip unit and the transmitting and receiving unit, and a pressure and key detection unit connected to the single chip unit, wherein: The transmitting and receiving unit receives the electromagnetic signal transmitted by the digitizer and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonance frequency and sends the resonance signal to the digitizer, so that the digitizer acquires the touch information of the electromagnetic pen; The first rectifying and filtering unit shapes and filters the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit to provide power for it. After the single-chip unit obtains power, it enters deep sleep after initialization; The second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs the signal to the single-chip unit to wake up the single-chip unit; The pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen; The single chip unit controls the duration of the shutdown time of the transmitting control unit according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet. The single-chip unit compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison result, and determines whether to wake up the single-chip unit according to the comparison result.

2. The digital electromagnetic pen according to claim 1, characterized in that: The single chip unit includes an ADC converter, a comparator, a time counter and a controller. When the single-chip unit obtains power, it enters deep sleep after initialization. The comparator compares the voltage output by the second rectifier and filter unit with the preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. The interrupt signal wakes up the single-chip unit, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit. The controller controls the length of time the transmitting control unit is turned off according to the pen tip pressure data and button status, thereby controlling the energy intensity of the resonant signal sent by the transmitting and receiving unit to the digital tablet.

3. The digital electromagnetic pen according to claim 1, characterized in that: The transmitting and receiving unit includes a winding coil and a capacitor connected in parallel.

4. The digital electromagnetic pen according to claim 1, characterized in that: The transmitting control unit includes a field effect transistor and a diode, the source of the field effect transistor is respectively connected to the input end of the pressure and key detection unit and one end of the transmitting and receiving unit, the drain is connected to the cathode of the diode, the gate is connected to the single chip unit, and the anode of the diode is connected to the other end of the transmitting and receiving unit.

5. An input system, characterized in that: Including digital electromagnetic pen and digital tablet, The digital electromagnetic pen comprises a single chip unit, a transmitting control unit and a transmitting and receiving unit connected in sequence, a first rectifying and filtering unit and a second rectifying and filtering unit connected in parallel between the single chip unit and the transmitting and receiving unit, and a pressure and key detection unit connected to the single chip unit. The transmitting and receiving unit receives the electromagnetic signal transmitted by the digitizer and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonance frequency and sends the resonance signal to the digitizer, so that the digitizer acquires the touch information of the electromagnetic pen; The first rectifying and filtering unit shapes and filters the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit to provide power for it. After the single-chip unit obtains power, it enters deep sleep after initialization; The second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs the signal to the single-chip unit to wake up the single-chip unit; The pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen; The single chip unit controls the duration of the shutdown time of the transmitting control unit according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet; The digital tablet obtains the touch information of the digital electromagnetic pen according to the resonance signal. The single-chip unit compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison result, and determines whether to wake up the single-chip unit according to the comparison result.

6. The input system according to claim 5, characterized in that: The single chip unit includes an ADC converter, a comparator, a time counter and a controller. When the single-chip unit obtains power, it enters deep sleep after initialization. The comparator compares the voltage output by the second rectifier and filter unit with the preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. The interrupt signal wakes up the ADC converter and the controller, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit. The controller controls the length of time the transmitting control unit is turned off according to the pen tip pressure data and button status, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet.

7. The input system according to claim 5, characterized in that: The transmitting control unit includes a field effect transistor and a diode, the source of the field effect transistor is respectively connected to the input end of the pressure and key detection unit and one end of the transmitting and receiving unit, the drain is connected to the cathode of the diode, the gate is connected to the single chip unit, and the anode of the diode is connected to the other end of the transmitting and receiving unit.

8. A control method of the input system according to any one of claims 5 to 7, characterized in that: The control method comprises the following steps: Step S1, the digital tablet transmits a fixed-frequency electromagnetic signal of a set duration; Step S2, when the digital electromagnetic pen is within the detection range of the digital tablet, the transmitting and receiving unit receives the electromagnetic signal emitted by the digital tablet and converts the electromagnetic signal into a corresponding electrical signal and outputs it to the first rectifying and filtering unit and the second rectifying and filtering unit, and generates resonance when the frequency of the electromagnetic signal is close to its own resonant frequency and sends the resonant signal to the digital tablet; Step S3, the first rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit. After the single-chip unit obtains power, it enters deep sleep after initialization. Meanwhile, the second rectifying and filtering unit performs shaping and filtering on the electrical signal output by the transmitting and receiving unit and then outputs it to the single-chip unit. Step S4, the single chip unit compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison output, and determines whether to wake up the single chip unit according to the comparison result. If the single chip unit is awakened, step S5 is executed, otherwise the single chip unit returns to the main program and enters deep sleep; Step S5, the pressure and key detection unit detects the pen tip pressure data and key status of the digital electromagnetic pen, and the single chip unit controls the length of the shutdown time of the transmitting control unit according to the detection result of the pressure and key detection unit, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet; Step S6, the digital tablet analyzes and restores the received resonance signal according to the energy indication beacon to obtain the touch information of the digital electromagnetic pen, wherein the energy indication beacon is the signal strength received by the transmitting and receiving unit when the transmitting control unit is turned off; Repeat steps S2-S6 until the digital electromagnetic pen leaves the detection range of the digital tablet.

9. The control method according to claim 8, characterized in that: The single chip unit includes an ADC converter, a comparator, a time counter and a controller. When the single chip unit enters deep sleep after initialization, the time counter starts timing; The comparator compares the voltage output by the second rectifying and filtering unit with a preset comparison voltage to generate a comparison output, and generates an interrupt signal at the rising edge of the comparison output. If an interrupt signal is generated within a preset time, the interrupt signal wakes up the ADC converter and the controller, and the time counter is reset to zero. The ADC converter reads the pen tip pressure data and key status detected by the pressure and key detection unit. The controller controls the length of the shutdown time of the transmitting control unit according to the pen tip pressure data and key status, thereby controlling the energy intensity of the resonance signal sent by the transmitting and receiving unit to the digital tablet; If no interrupt signal is generated within the preset time, the time counter overflows and generates an interrupt. If the comparator is disabled at this time, the time counter is reset to zero and the comparator is re-enabled, and the program returns to the main program and enters deep sleep. If the comparator is enabled at this time, the ADC converter reads the pen tip pressure data and button status detected by the pressure and button detection unit and returns to the main program and enters deep sleep.

10. The control method according to claim 9, characterized in that: In step S4, the single chip unit controls the duration of the closing time of the emission control unit according to the detection result of the pressure and key detection unit: If the key switch is not pressed and the pen tip is not under pressure, the emission control unit is turned off; If it is detected that the button switch is pressed, the emission control unit will turn on, and if the detected pressure value is 0, the emission control unit will be turned off for the time period corresponding to the pressure value of 0, and if the detected pressure value is not 0, the emission control unit will perform a closing or opening operation according to the size of the pressure value and control the opening time according to the preset energy code.

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