Signal generating circuit, touch chip and active pen

Abstract

The embodiment of the utility model provides a signal generation circuit, a chip and an active pen. The signal generation circuit comprises a booster circuit, a charge pump and a coding circuit, the input end of the booster circuit is connected to a power supply, the output end of the booster circuit is connected to the input end of the charge pump, and the output end of the charge pump is connected to the coding circuit; the booster circuit is used for boosting power supply voltage provided by the power supply to preset voltage; the charge pump is used for increasing the preset voltage by a preset integer multiple to generate a target voltage; and the coding circuit is used for receiving the target voltage and generating a coding signal at least based on the target voltage. Based on the scheme, the signal generation circuit provided by the embodiment of the utility model can have relatively low design and use cost and relatively high working efficiency.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of touch control technology, and in particular to a signal generating circuit, a touch control chip, and an active pen. Background Art

[0002] With the development of touch technology and mobile terminal technology, more and more mobile terminals use touch for human-computer interaction. At present, the touch screens used in mobile terminals are mainly capacitive touch screens. In addition to being able to be operated directly by fingers, capacitive touch screens can also be operated by an active touch stylus (hereinafter referred to as an active pen) instead of fingers. When using an active pen for touch operation, the active pen usually needs to output a higher coding voltage to achieve communication between the active pen and the terminal device.

[0003] In the related art, active pens usually use a boost chopper circuit (also called a Boost circuit) to increase the low-voltage power supply voltage to a higher target voltage to provide a higher coding voltage. This causes the devices in the Boost circuit to need to withstand a higher withstand voltage value, which leads to an increase in device cost. In addition, since the voltage amplification factor is high in the process of using the Boost circuit for boosting, and the load current in the active pen application is usually very low, this leads to a low boost efficiency of the Boost circuit, resulting in a low working efficiency of the entire circuit. Utility Model Content

[0004] In view of this, one of the technical problems solved by the embodiments of the present application is to provide a signal generating circuit, a touch chip and an active pen, which are used to at least partially solve the above technical problems.

[0005] In a first aspect, an embodiment of the present application provides a signal generating circuit, including: a boost circuit, a charge pump, and a coding circuit. The input end of the boost circuit is connected to a power supply, the output end of the boost circuit is connected to the input end of the charge pump, and the output end of the charge pump is connected to the coding circuit. The boost circuit is used to boost the power supply voltage provided by the power supply to a preset voltage; the charge pump is used to increase the preset voltage by a preset integer multiple to generate a target voltage. The coding circuit is used to receive the target voltage and generate a coding signal based at least on the target voltage.

[0006] In a second aspect, an embodiment of the present application further provides a touch control chip, comprising a signal generating circuit as provided in the first aspect.

[0007] In a third aspect, an embodiment of the present application further provides an active pen, comprising the chip provided in the second aspect.

[0008] In the technical solution provided by the embodiment of the present application, the power supply voltage is increased to a preset voltage by a boost circuit as the first stage boost, and the preset voltage is further increased to a target voltage by a charge pump as the second stage boost and provided to the coding circuit. Since the boost circuit and the charge pump are used to achieve two-stage boosting, compared with the one-stage boosting solution using only the boost circuit in the related art, the withstand voltage requirements of the devices in the boost circuit and the charge pump are greatly reduced, thereby reducing the design and use cost of the signal generating circuit. In addition, due to the use of the charge pump, the output voltage of the boost circuit is a preset voltage that is smaller than the target voltage, so the boost multiple of the boost circuit can be lower, and the boost efficiency of the boost circuit is correspondingly improved. At the same time, the charge pump path loss is small and the efficiency is high. Therefore, the signal generating circuit provided by the present application can have a higher working efficiency while having a lower design and use cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Hereinafter, some specific embodiments of the present application will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0010] Figure 1 A schematic diagram of a signal generating circuit provided for a related technology;

[0011] Figure 2 A schematic diagram of the structure of a signal generating circuit provided in an embodiment of the present application;

[0012] Figure 3 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0013] Figure 4 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0014] Figure 5 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0015] Figure 6 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0016] Figure 7 A schematic diagram of a coding signal of a signal generating circuit provided in an embodiment of the present application;

[0017] Figure 8 A schematic diagram of the structure of a signal generating circuit provided in an embodiment of the present application;

[0018] Fig. 9 A schematic diagram of a coding signal of a signal generating circuit provided in an embodiment of the present application;

[0019] Fig.10 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application; and

[0020] Fig.11 A circuit structure diagram of a signal generating circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, 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 part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field should fall within the scope of protection of the embodiments of the present application.

[0022] Capacitive touch screens are widely used as touch screens for mobile terminals due to their good clarity, light transmittance and touch feel. In addition to being able to be directly touched by fingers, capacitive touch screens can also be touched by an active touch stylus (hereinafter referred to as an active pen) instead of fingers. In the application scenario where the active pen is used in conjunction with a terminal device, the active pen is used to write or input instructions to a terminal device with a capacitive touch screen, such as a mobile terminal device, a computer screen, a drawing board, etc., to achieve human-computer interaction. In order to achieve communication between the active pen and the terminal device, the active pen needs to output a coding signal. The coding signal is usually a high-voltage signal to ensure that the communication signal between the active pen and the terminal device has a high signal-to-noise ratio. In order for the active pen to output such a coding signal, the signal generating circuit in the active pen needs to boost the power supply voltage provided by the power supply to the target voltage, and generate a coding signal based on such a target voltage and provide it to the active pen (for example, the tip of the active pen), and the active pen outputs the coding signal.

[0023] Figure 1 It is a structural diagram of a signal generating circuit provided by the related technology. Figure 1As shown, the signal generating circuit includes a Boost circuit and a coding circuit. The input end of the Boost circuit is connected to a power supply (also referred to as an input power supply) to receive the power supply voltage of the input power supply, and directly convert the power supply voltage into a desired DC voltage (i.e., a target voltage) to provide to the coding circuit. The input power supply usually has a relatively low DC voltage, for example, the power supply voltage of the input power supply is usually 1.0V to 5V. The target voltage is usually a relatively high DC voltage, for example, it can be 60V, 40V or 20V. The input end of the coding circuit is connected to the output end of the Boost circuit, and the output end of the coding circuit is connected to a drive electrode, which is usually located in the pen tip of the active pen. The coding circuit generates a coding signal based on the target voltage to provide to the drive electrode.

[0024] exist Figure 1 In the signal generating circuit shown, a boost circuit is used to directly boost the power supply voltage to a target voltage. The boost circuit includes an inductor L01, a main power tube Q01, a freewheeling diode D01, and a capacitor C01. The first end of the inductor L01 is connected to a power supply, wherein the power supply can be a battery, providing a power supply voltage V (also referred to as VBAT). The second end of the inductor L01 is connected to the first end of the main power tube Q01 and the positive pole of the freewheeling diode D01. The second end of the main power tube Q01 is connected to the ground, and the third end of the main power tube Q01 is connected to a control module (not shown) to receive a control signal. The cathode of the freewheeling diode D01 is connected to the input end of the coding circuit and the first end of the capacitor C01, and the second end of the capacitor C01 is connected to the ground.

[0025] Among them, the inductor L01 and the main power tube Q01 constitute a basic energy conversion unit. When the main power tube Q01 is turned on, the inductor L01 is charged, and the energy stored in the inductor L01 gradually increases. When the main power tube is turned off, the inductor L01 is discharged, and the energy stored in the inductor L01 flows to the capacitor C01 through the freewheeling diode D01. The control module intermittently controls the number of times the main power tube Q01 is turned on and off by applying a control signal to the third end of the main power tube Q01, so that the voltage on the capacitor C01 gradually increases to the target voltage HV to be provided to the coding circuit. The coding circuit includes a first switch S1 and a second switch S2. The first switch S1 and the second switch S2 are alternately turned on, so that the output end of the coding circuit outputs a coding signal to the driving electrode TX.

[0026] exist Figure 1In the signal generating circuit shown, the main power tube Q01, the freewheeling diode D01 and the capacitor C01 all need to have a relatively high withstand voltage, that is, the main power tube Q01, the freewheeling diode D01 and the capacitor C01 all need to be greater than HV. The higher the withstand voltage of the device, the larger the device package, and the correspondingly more expensive the device price. In addition, the high withstand voltage of the device also limits the device selection. Therefore, Figure 1 The signal generating circuit shown is relatively expensive to design and use.

[0027] In addition, Figure 1 In the signal generating circuit shown, a Boost circuit is used to increase the low voltage DC power supply voltage to a target voltage, and the voltage amplification factor is relatively large. As known to those skilled in the art, for a Boost circuit, the greater the voltage amplification factor, the greater the various losses such as the conduction loss of the main power tube and the freewheeling diode in the boost circuit, and the lower the boost efficiency of the Boost circuit (i.e., the energy conversion efficiency between the input and output of the Boost circuit). In addition, in active pen applications, the load is a smaller capacitive load (i.e., a smaller capacitor), and the current flowing through the load is usually very low, which makes the boost efficiency of the Boost circuit even lower. For example, in an active pen application, the Boost circuit increases the power supply voltage of 3.6V to a target voltage of 60V, and the boost efficiency of the boost circuit is only 40%-60%.

[0028] To this end, an embodiment of the present application provides a signal generating circuit, which uses a boost circuit and a charge pump to increase the power supply voltage to a target voltage through two-stage boosting, and provides it to a coding circuit. The coding circuit generates a coding signal based on the target voltage, thereby reducing the voltage resistance requirements of the devices in the signal generating circuit while improving its working efficiency, thereby realizing a signal generating circuit with lower design and use costs and higher efficiency.

[0029] The specific implementation of the embodiment of the present application is further explained below in conjunction with the accompanying drawings of the embodiment of the present application.

[0030] Figure 2 FIG. 2 shows a schematic diagram of a signal generating circuit according to an embodiment of the present application. Figure 2 As shown, the signal generating circuit 200 includes: a boost circuit 202, a charge pump 204 and a coding circuit 206;

[0031] The input end of the boost circuit 202 is connected to the power supply 100 , the output end of the boost circuit 202 is connected to the input end of the charge pump 204 , and the output end of the charge pump 204 is connected to the coding circuit 206 ;

[0032] The boost circuit 202 is used to boost the power voltage V provided by the power supply 100 to a preset voltage V1;

[0033] The charge pump 204 is used to increase the preset voltage V1 by a preset integer multiple to generate a target voltage HV;

[0034] The coding circuit 206 is configured to receive the target voltage HV and generate a coding signal at least based on the target voltage HV.

[0035] The power supply 100 may be a battery. For example, in an active pen application, the power supply may be a battery of the active pen.

[0036] The input end of the boost circuit 202 is connected to the power supply 100 to receive the power supply voltage V provided by the power supply 100. The boost circuit 202 can be an energy storage and energy release circuit composed of an inductor and a switch element. When the switch element is turned on, the inductor stores energy; when the switch element is turned off, the inductor releases energy and provides a preset voltage, which is greater than the power supply voltage.

[0037] The boost circuit 202 can gradually adjust the power supply voltage V to the preset voltage V1 by storing and releasing the energy of the inductor. In one implementation of the present application, the boost circuit 202 is a boost circuit. The structure of the boost circuit can be the same as Figure 1 The structure of the boost circuit shown is similar and will not be described again here.

[0038] The charge pump 204 uses the charging and discharging principle of the capacitor to achieve voltage boosting. In the present embodiment, the charge pump 204 can boost the preset voltage by a preset integer multiple to generate a target voltage. The preset integer multiple can be any one of 2, 4 or 6. That is, the charge pump 204 can be any one of a 2-fold pressure type charge pump, a 4-fold pressure type charge pump or a 6-fold pressure type charge pump. When the preset integer multiple is 2, the boost circuit 202 needs to boost the power supply voltage to 1 / 2 times the target voltage, that is, the preset voltage is equal to 1 / 2 times the target voltage. Similarly, when the preset integer multiple is 4, the boost circuit 202 needs to boost the power supply voltage to 1 / 4 times the target voltage, that is, the preset voltage is equal to 1 / 4 times the target voltage. When the preset integer multiple is 6, the boost circuit 202 needs to boost the power supply voltage to 1 / 6 times the target voltage, that is, the preset voltage is equal to 1 / 6 times the target voltage.

[0039] As the boost multiple that the charge pump 204 can achieve increases, more energy storage capacitors are required in the charge pump, that is, the number of capacitors in the charge pump will also increase, and the efficiency of the charge pump may decrease. Therefore, in one implementation of the present application, the preset integer multiple is 2. That is, the charge pump is a 2-times-pressure charge pump. Generally, under light load (i.e., low load rate), the efficiency of the 2-times-pressure charge pump is greater than 90%.

[0040] An output terminal of the charge pump 204 is connected to the coding circuit 206 to provide a target voltage to the coding circuit, and the coding circuit generates a coding signal based on at least the target voltage.

[0041] In the embodiment of the present application, the power supply voltage is increased to a preset voltage by a boost circuit as the first stage boost, and the preset voltage is further increased to a target voltage by a charge pump as the second stage boost and provided to the coding circuit. Since the boost circuit and the charge pump are used to achieve two-stage boosting, the withstand voltage requirements of the devices in the boost circuit and the charge pump are greatly reduced compared with the solution of using only one stage boosting, thereby reducing the overall design and use cost of the signal generating circuit provided in the present application. In addition, since the output voltage of the boost circuit is a preset voltage smaller than the target voltage, the boost multiple of the boost circuit can be lower. The smaller the boost multiple of the boost circuit, the smaller its loss will be, so the boost efficiency of the boost circuit is improved. At the same time, since the charge pump path loss is small and the efficiency is high, the signal generating circuit provided in the present application has high efficiency while having low cost.

[0042] For example, for an active pen application with a power supply voltage of 3.6V and a target voltage of 60V, the boost circuit uses Figure 1 In the Boost circuit shown in the figure, and the charge pump is a 2x voltage type charge pump, the boost circuit only needs to increase the power supply voltage of 3.6V to 30V, and then the charge pump increases the preset voltage of 30V by 2 times to 60V. Since the efficiency of the Boost circuit is related to the voltage gain, when the power supply voltage of 3.6V is increased to 30V, its voltage gain is 8.3, and when the power supply voltage of 3.6V is increased to 60V, its voltage gain is 16.7. The efficiency corresponding to the voltage gain of 16.7 times is lower than the efficiency corresponding to the voltage gain of 8.3 times, and the difference between the two is usually about 20%. Therefore, in this embodiment, the boost circuit increases the power supply voltage of 3.6V to 30V, which can increase the efficiency of the Boost circuit from 40-60% to 60-80%. At the same time, under light load, the efficiency of the 2x voltage type charge pump is greater than 90%. The combined efficiency of the two can reach 54-73% or more, which is significantly higher than Figure 1 The case of using a Boost circuit to directly boost the voltage is shown (i.e., 40-60%). At the same time, due to the use of two-stage boost, the withstand voltage requirement of at least some devices in the Boost circuit and the 2x voltage charge pump will be reduced from greater than 60V to greater than 30V, that is, the withstand voltage requirement of the device is greatly reduced, thereby reducing the device cost and increasing the selection range, thereby reducing the design and use cost of the entire signal generating circuit.

[0043] based on Figure 2 The signal generating circuit shown, Figure 3 A structural schematic diagram of a signal generating circuit according to an embodiment of the present application is shown. Figure 3 The boost circuit 302 and the coding circuit 306 of the signal generating circuit 300 are Figure 2 The boost circuit 202 and the coding circuit 206 in the signal generating circuit 200 shown have the same structure and working principle. Figure 3 The signal generating circuit 300 shown gives Figure 2 The circuit implementation of the charge pump in the signal generating circuit 200 is shown.

[0044] like Figure 3 As shown, the charge pump 304 includes a first capacitor C1, a second capacitor C2, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, and a fourth switch tube Q4. The first switch tube Q1 and the second switch tube Q2 are connected in series between the output end of the boost circuit 302 and the input end of the coding circuit 306, and the third switch Q3 and the fourth switch Q4 are connected in series between the output end of the boost circuit 302 and the ground. The first end of the first capacitor C1 is connected to the common end of the first switch tube Q1 and the second switch tube Q2, and the second end of the first capacitor C1 is connected to the common end of the third switch tube Q3 and the fourth switch tube Q4; the first end of the second capacitor C2 is connected to the input end of the coding circuit 306, and the second end of the second capacitor C2 is grounded.

[0045] In this embodiment, the first switch tube Q1 and the fourth switch tube Q4 form a group of switches, the second switch tube Q2 and the third switch tube Q3 form a group of switches, and the two groups of switches are mutually exclusive turned on or off at a certain frequency. Specifically, the control end of the first switch tube Q1 to the fourth switch tube Q4 is connected to a control module (not shown). The control module mutually exclusively turns on or off a group of switches consisting of the first switch tube Q1 and the fourth switch tube Q4 and a group of switches consisting of the second switch tube Q2 and the third switch tube Q3 at a certain frequency so that the charge pump 304 boosts the received preset voltage V1 to HV, where V1=1 / 2HV. In this embodiment, the first switch tube Q1 to the fourth switch tube Q4 can be a field effect transistor. The control module may include a micro control unit (not shown) and a drive module (not shown). The drive module is connected to the control end of the first switch tube Q1 to the fourth switch tube Q4, for driving the first switch tube Q1 to the fourth switch tube Q4. The micro control unit is connected to the driving module and controls the driving mode of the driving module so that the driving module generates a square wave with a certain duty cycle to control the on and off of the first switch tube Q1 to the fourth switch tube Q4.

[0046] In this embodiment, when the first switch tube Q1 and the fourth switch tube Q4 are turned on, and the second switch tube Q2 and the third switch tube Q3 are turned off, the voltages across the first capacitor C1 are 1 / 2HV and 0V respectively, and at this time, the voltage difference across the second switch tube and the third switch tube is 1 / 2HV. Next, when the second switch tube Q2 and the third switch tube Q3 are turned on, and the first switch tube Q1 and the fourth switch tube Q4 are turned off, the voltages across the first capacitor C1 are HV and 1 / 2HV respectively, and at this time, the voltage difference across the first switch tube Q1 and the fourth switch tube Q4 is only 1 / 2HV. That is, during the entire operation process, the withstand voltage values ​​of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4 and the first capacitor C1 only need to meet 1 / 2HV. Compared to Figure 1 In the one-stage boost scheme in the signal generating circuit shown, the device does not need to withstand the high voltage HV, which reduces the requirements on the device and reduces the circuit design cost of the signal generating circuit.

[0047] exist Figure 3 In the charge pump 304 shown in FIG. 1 , the withstand voltage of the second capacitor C2 needs to meet HV. In order to optimize the withstand voltage of the second capacitor C2, Figure 4 A structural schematic diagram of a signal generating circuit according to an embodiment of the present application is provided. Figure 4 The signal generating circuit 400 is shown with Figure 3 The difference between the illustrated signal generating circuit 300 is that the circuit implementation of the charge pump is different.

[0048] exist Figure 4 In the signal generating circuit 400 shown, the charge pump 404 includes a first capacitor C1, a second capacitor C2, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, and a fourth switch tube Q4. The first switch tube Q1 and the second switch tube Q2 are connected in series between the output end of the boost circuit 302 and the input end of the coding circuit 306, and the third switch Q3 and the fourth switch Q4 are connected in series between the output end of the boost circuit 302 and the ground. The first end of the first capacitor C1 is connected to the common end of the first switch tube Q1 and the second switch tube Q2, and the second end of the first capacitor C1 is connected to the common end of the third switch tube Q3 and the fourth switch tube Q4; the first end of the second capacitor C2 is connected to the input end of the coding circuit 306, and the second end of the second capacitor C2 is connected to the output end of the boost circuit 302.

[0049] In this embodiment, the charge pump 400 and Figure 3 The control process and working principle of the charge pump 300 in the embodiment shown are the same, the only difference is that Figure 4 The second end of the second capacitor C2 is connected to the output end of the boost circuit 302, so that the withstand voltage of the second capacitor C2 is also reduced from HV to 1 / 2HV. Figure 4In the embodiment shown, the withstand voltage of all devices in the charge pump only needs to meet 1 / 2HV. Figure 1 Compared with the one-stage boost scheme in the signal generating circuit shown, the devices do not need to withstand the high voltage HV, which reduces the voltage resistance requirements for the devices and reduces the circuit design cost of the signal generating circuit.

[0050] exist Figures 2 to 4 In the signal generating circuit shown in FIG. 1 , the voltage boosting circuit may include a boost circuit. Figure 5 and 6 In the embodiment, the boost circuit is a boost circuit 502 and 602, and the boost circuit 502 and 602 include: an inductor L1, a switch tube Q5, a freewheeling diode D1 and a third capacitor C3. The first end of the inductor L1 is connected to the power supply 100, and the second end of the inductor L1 is connected to the first end of the switch tube Q5 and the positive electrode of the freewheeling diode D1. The second end of the switch tube Q5 is connected to the ground, and the third end of the switch tube Q5 is connected to the control module (not shown) to receive the control signal. The cathode of the freewheeling diode D1 is connected to the input end of the charge pump 504 and 604 and the first end of the third capacitor C3, and the second end of the third capacitor C3 is connected to the ground.

[0051] In this embodiment, the switch tube Q5 may be a field effect transistor. The control module connected to the switch tube Q5 may be Figure 3 and Figure 4 The control module in the embodiment shown. The control module intermittently controls the on and off of the switch tube Q5. By controlling the number of on and off times of the switch tube Q5, the voltage on the third capacitor C3 can be increased to V1, V1 = 1 / 2HV. The freewheeling diode D1 can prevent the energy on the third capacitor C3 from flowing back to the power supply. The specific process of Boost in this embodiment is shown in FIG. Figure 1 The specific process of the boost circuit shown will not be repeated here.

[0052] Since the boost circuit in this embodiment only needs to boost the power supply voltage V to 1 / 2HV, the switch tube Q5, the freewheeling diode D1 and the third capacitor C3 in the boost circuit only need to meet 1 / 2HV. Figure 1 Compared with the one-stage boost scheme in the signal generating circuit shown, the device does not need to withstand the high voltage HV, which reduces the requirements on the device and reduces the circuit design cost of the signal generating circuit.

[0053] Figure 5 and Figure 6 The embodiment shown in the figure further shows a circuit structure diagram of a coding circuit provided in the embodiment of the present application. Figure 5 and Figure 6As shown, the coding circuit 506 and 606 includes a switch module and a control module (not shown) connected to the control end of the switch module. The switch module includes: a first switch S1 and a second switch S2, the first switch S1 and the second switch S2 are connected in series between the output end of the charge pump 504 and 604 and the ground, and the common end between the first switch S1 and the second switch S2 is connected to the output end of the coding circuit 506 and 606;

[0054] The control module (not shown) is used to control the state of the switch in the switch module so that the output terminals of the coding circuits 506 and 606 output coding signals, wherein the coding signals include two voltage levels with amplitudes of ground voltage and target voltage.

[0055] The control module in this embodiment can be designed to be integrated with the control module that controls the boost circuit and each switch tube in the charge pump, or it can be designed independently of the control module that controls the boost circuit and each switch tube in the charge pump. This embodiment does not limit this.

[0056] In a specific implementation, the control module controls the switches in the switch module including: a first stage and a second stage;

[0057] In the first stage, the first switch S1 is in a closed state and the second switch S2 is in an open state, and the output terminals of the coding circuits 506 and 606 output the target voltage;

[0058] In the second stage, when the first switch S1 is in an open state and the second switch S2 is in a closed state, the output terminals of the coding circuits 506 and 606 output a ground voltage.

[0059] The control module periodically executes the first stage and the second stage in the above manner, thereby simply controlling the generation of Figure 7 The coding signal is shown, where 0 represents the ground voltage and HV represents the target voltage.

[0060] Since the load in the active pen application is a capacitive load, there will inevitably be energy loss when charging the capacitive load. The energy loss is proportional to the square of the charging voltage difference. In order to reduce the loss of the coding signal when charging the capacitive load and improve the coding efficiency, the following are provided: Figure 8 The signal generating circuit shown. Figure 8 The signal generation circuit shown is Figures 2 to 7 The difference between the signal generating circuit shown is that Figure 8In the signal generating circuit shown, the coding circuit 806 includes a first input terminal and a second input terminal, the first input terminal of the coding circuit 806 is connected to the output terminal of the charge pump 804, and the second input terminal of the coding circuit 806 is connected to the output terminal of the boost circuit 802. The coding circuit is used to receive the preset voltage output by the boost circuit and the target voltage output by the charge pump to generate a coding signal based on the preset voltage and the target voltage. The coding signal is a step signal and includes three voltage levels with amplitudes of ground voltage, preset voltage and target voltage.

[0061] In this embodiment, the structure and working principle of the boost circuit 802 and the charge pump 804 are similar to those of Figures 2 to 6 The structures and working principles of the boost circuit and the charge pump in the illustrated embodiment are the same and will not be described in detail herein.

[0062] In this embodiment, by connecting the first input terminal of the coding circuit 806 to the output terminal of the charge pump 804 and the second input terminal of the coding circuit 806 to the output terminal of the boost circuit 802, the coding circuit can generate Fig. 9 The staircase coding signal shown. For capacitive loads, the lower the single charging voltage, the smaller the power loss. Specifically, the energy loss is proportional to the square of the charging voltage difference. Figure 7 Compared with the coding signal shown, Fig. 9 The voltage difference between the two voltage levels in the step coding signal shown is significantly reduced, so the energy loss is significantly reduced, thereby improving the coding efficiency. For example, when the preset voltage is 1 / 2 of the target voltage, the Fig. 9 The step coding signal shown can save 50% of energy and achieve higher coding efficiency.

[0063] Fig.10 and Fig.11 Two structural schematic diagrams of a signal generating circuit provided according to an embodiment of the present application are shown. Fig.10 and Fig.11 The boost circuit and charge pump in the embodiment have the same structure and working principle as the boost circuit and charge pump in the aforementioned embodiment, and will not be described in detail here. Fig.10 and Fig.11 The difference between the signal generating circuit shown in the figure and the signal generating circuit in the above-mentioned embodiment lies in the different structure of the coding circuit. Fig.10 and Fig.11As shown, the coding circuits 906 and 1006 include a switch module and a control module connected to the control end of the switch module; the switch module includes: a first switch S1, a second switch S2 and a third switch S3, the first switch S1 and the second switch S2 are connected in series between the output end of the charge pump 904 and 1004 and the ground, the common end between the first switch S1 and the second switch S2 is connected to the output end of the coding circuits 906 and 1006, the first end of the third switch S3 is connected to the output end of the boost circuit 902 and 1002, and the second end of the third switch S3 is connected to the output end of the coding circuits 906 and 1006. The control module (not shown) is used to control the state of the switches in the switch module so that the output end of the coding circuits 906 and 1006 outputs a coding signal.

[0064] The control module in this embodiment can be designed to be integrated with the control module for controlling the boost circuit and each switch tube in the charge pump, or it can be designed independently of the control module for controlling the boost circuit and each switch tube in the charge pump, and this embodiment does not limit this.

[0065] In a specific implementation, the control module controls the switches in the switch module including: a first stage, a second stage, a third stage and a fourth stage;

[0066] In the first stage, the third switch S3 is in a closed state, and the first switch S1 and the second switch S2 are in an open state, and the output terminals of the coding circuits 906 and 1006 have a preset voltage;

[0067] In the second stage, the first switch S1 is in a closed state, and the second switch S2 and the third switch S3 are in an open state, and the output terminals of the coding circuits 906 and 1006 output the target voltage;

[0068] In the third stage, the third switch S3 is in a closed state, and the first switch S1 and the second switch S2 are in an open state, and the output terminals of the coding circuits 906 and 1006 have a preset voltage;

[0069] In the fourth stage, the second switch S2 is in a closed state, and the first switch S1 and the third switch S3 are in an open state, and the output terminals of the coding circuits 906 and 1006 output a ground voltage.

[0070] In this embodiment, the control module controls the conduction and closing of the first switch S1, the second switch S2 and the third switch S3 in this way to achieve the following Fig. 9 The staircase coding signal shown in the figure. Since for capacitive loads, the energy loss is proportional to the square of the charging voltage difference. Therefore, Figure 7 Compared with the coding signal shown, Fig. 9The voltage difference between the two levels of voltage in the step coding signal shown is significantly reduced, so the energy loss is significantly reduced, thereby improving the coding efficiency.

[0071] An embodiment of the present application provides a touch control chip, including the signal generating circuit in any embodiment of the present application.

[0072] The embodiment of the present application also provides an active pen, which includes the touch chip provided in the above embodiment. When the active pen touches the capacitive touch screen of the terminal device, the touch chip provides a coding signal to the tip of the active pen.

[0073] The terminal device of the embodiment of the present application exists in various forms, including but not limited to:

[0074] (1) Mobile communication devices: These devices are characterized by their mobile communication functions and their main purpose is to provide voice and data communications. These terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones.

[0075] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access features. These terminals include: PDA, MID and UMPC devices, such as iPad.

[0076] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0077] (4) Server: A device that provides computing services. The server consists of a processor 810, a hard disk, memory, a system bus, etc. The server is similar to a general computer architecture, but because it needs to provide highly reliable services, it has higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0078] (5) Other electronic devices with data interaction functions.

[0079] Thus far, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired results. Additionally, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing may be advantageous.

[0080] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0081] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A signal generating circuit, characterized in that: include: Boost circuit, charge pump and coding circuit; The input end of the boost circuit is connected to the power supply, the output end of the boost circuit is connected to the input end of the charge pump, and the output end of the charge pump is connected to the coding circuit; The boost circuit is used to boost the power voltage provided by the power supply to a preset voltage; The charge pump is used to increase the preset voltage by a preset integer multiple to generate a target voltage; The coding circuit is used to receive the target voltage and generate a coding signal based at least on the target voltage.

2. The signal generating circuit according to claim 1, wherein: The preset integer multiple is 2.

3. The signal generating circuit according to claim 2, wherein: The charge pump comprises a first capacitor, a second capacitor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; The first switch tube and the second switch tube are connected in series between the output end of the boost circuit and the first input end of the coding circuit, and the third switch and the fourth switch are connected in series between the output end of the boost circuit and the ground; The first end of the first capacitor is connected to the common end of the first switch tube and the second switch tube, and the second end of the first capacitor is connected to the common end of the third switch tube and the fourth switch tube; and the first end of the second capacitor is connected to the first input end of the coding circuit, and the second end of the second capacitor is grounded.

4. The signal generating circuit according to claim 2, wherein: The charge pump comprises a first capacitor, a second capacitor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; The first switch tube and the second switch tube are connected in series between the output end of the boost circuit and the first input end of the coding circuit, and the third switch and the fourth switch are connected in series between the output end of the boost circuit and the ground; The first end of the first capacitor is connected to the common end of the first switch tube and the second switch tube, and the second end of the first capacitor is connected to the common end of the third switch tube and the fourth switch tube; the first end of the second capacitor is connected to the input end of the coding circuit, and the second end of the second capacitor is connected to the output end of the boost circuit.

5. The signal generating circuit according to claim 1, characterized in that: The voltage-boosting circuit includes a boost circuit.

6. The signal generating circuit according to claim 1, wherein: The coding circuit includes a switch module and a control module connected to a control end of the switch module; The switch module comprises: a first switch and a second switch, wherein the first switch and the second switch are connected in series between the output end of the charge pump and the ground, and a common end between the first switch and the second switch is connected to the output end of the coding circuit; The control module is used to control the state of the switch in the switch module so that the output end of the coding circuit outputs the coding signal, wherein the coding signal includes two voltage levels with amplitudes of ground voltage and the target voltage.

7. The signal generating circuit according to claim 6, wherein: The control of the switch in the switch module by the control module includes: a first stage and a second stage; In the first stage, the first switch is in a closed state and the second switch is in an open state, and the output end of the coding circuit outputs the target voltage; In the second stage, when the first switch is in an open state and the second switch is in a closed state, the output end of the coding circuit outputs a ground voltage.

8. The signal generating circuit according to claim 1, wherein: The coding circuit comprises a first input terminal and a second input terminal, the first input terminal of the coding circuit is connected to the output terminal of the charge pump, and the second input terminal of the coding circuit is connected to the output terminal of the boost circuit; The coding circuit is used to receive the preset voltage and the target voltage to generate the coding signal based on the preset voltage and the target voltage, wherein the coding signal is a step signal and includes three levels of voltages with amplitudes of ground voltage, the preset voltage and the target voltage.

9. The signal generating circuit according to claim 8, wherein: The coding circuit includes a switch module and a control module connected to a control end of the switch module; The switch module comprises: a first switch, a second switch and a third switch, wherein the first switch and the second switch are connected in series between the output end of the charge pump and the ground, a common end between the first switch and the second switch is connected to the output end of the coding circuit, a first end of the third switch is connected to the output end of the boost circuit, and a second end of the third switch is connected to the output end of the coding circuit; The control module is used to control the state of the switch in the switch module so that the output end of the coding circuit outputs the coding signal.

10. The signal generating circuit according to claim 9, wherein: The control of the switch in the switch module by the control module includes: a first stage, a second stage, a third stage and a fourth stage; In the first stage, the third switch is in a closed state, and the first switch and the second switch are in an open state, and the output end of the coding circuit has the preset voltage; In the second stage, the first switch is in a closed state, and the second switch and the third switch are in an open state, and the output end of the coding circuit outputs the target voltage; In the third stage, the third switch is in a closed state, and the first switch and the second switch are in an open state, and the output end of the coding circuit has the preset voltage; In the fourth stage, the second switch is in a closed state, and the first switch and the third switch are in an open state, and the output end of the coding circuit outputs the ground voltage.

11. A touch chip, characterized in that: The method comprises the signal generating circuit according to any one of claims 1 to 10.

12. An active pen, characterized in that: Comprising the touch control chip according to claim 11.

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