Positive and negative voltage driving circuit, chip, active stylus and driving method

Patent metadata

Field	Value
Publication number	US-2021041984-A1
Application number	US-202017060004-A
Country	US
Kind code	A1
Filing date	Sep 30, 2020
Priority date	Aug 8, 2019
Publication date	Feb 11, 2021
Grant date	—

Abstract

Some embodiments of the present disclosure provide a positive and negative voltage driving circuit. The positive and negative voltage driving circuit includes: a positive and negative voltage generating module and a control module. The positive and negative voltage generating module includes a switch module. The control module is configured to control a turn-off state and a turn-on state of the switch module to enable the positive and negative voltage generating module to output a positive voltage and a negative voltage to a stylus tip of an active stylus. The positive and negative voltage driving circuit of the embodiments of the present disclosure can significantly reduce the driving power consumption of the active stylus while ensuring driving effects.

First claim

What is claimed is:

1 . A positive and negative voltage driving circuit, comprising:
a positive and negative voltage generating module comprising a switch module; and a control module being configured to control a turn-off state and a turn-on state of the switch module, to enable the positive and negative voltage generating module to alternately output a positive voltage and a negative voltage to a stylus tip of an active stylus.

2 . The positive and negative voltage driving circuit according to claim 1 , wherein the positive and negative voltage generating module further comprises a first positive voltage generating module and a first negative voltage generating module; wherein,
the first positive voltage generating module is configured to generate the positive voltage, one end of the first positive voltage generating module is connected to the ground, and the other end of the first positive voltage generating module is connected to the stylus tip; the first negative voltage generating module is configured to generate the negative voltage, one end of the first negative voltage generating module is connected to the ground, and the other end of the first negative voltage generating module is connected to the stylus tip.

3 . The positive and negative voltage driving circuit according to claim 2 , wherein the first positive voltage generating module further comprises a first boosting unit, the first boosting unit comprises a first inductor and a first diode, and the first boosting unit is configured to receive a power supply unit to charge the first inductor and output energy to the stylus tip; and wherein:
the active stylus comprises a stylus housing, and the control module controls the switch module in stages including a charging stage and a discharging stage; wherein, in the charging stage, the control module controls the switch module to enable the power supply unit to charge the first inductor; in the discharging stage, the control module controls the switch module to enable the energy charged by the first inductor in the charging stage to be transferred to a capacitor between the stylus tip and the stylus housing; and the first diode is configured to maintain a voltage charged by the capacitor in the discharging stage; the first negative voltage generating module comprises a second boosting unit, the second boosting unit comprises a second inductor and a second diode, and the second boosting unit is configured to receive the power supply unit to charge the second inductor and output energy to the stylus tip; and the control module controls the switch module in stages including the charging stage and the discharging stage; wherein, in the charging stage, the control module controls the switch module to enable the power supply unit to charge the second inductor; in the discharging stage, the control module controls the switch module to enable the energy charged by the second inductor in the charging stage to be transferred to a capacitor of the stylus tip; and the second diode is configured to maintain the voltage charged by the capacitor in the discharge stage.

4 . The positive and negative voltage driving circuit according to claim 3 , wherein the switch module comprises a fourth switch, an eighth switch, a first switch, a second switch, a third switch, a fifth switch, a sixth switch and a seventh switch, and a control terminal of the fourth switch is grounded, a control terminal of the eighth switch is connected to the power supply unit, one end of the first switch is connected to the power supply unit, the other end of the first switch is connected to one end of the first inductor, the other end of the first inductor is connected to one end of the second switch and an anode of the first diode, the other end of the second switch is grounded, a cathode of the first diode is connected to one end of the third switch and one end of the fourth switch, and the other end of the fourth switch is connected to the stylus tip, and one end of the fifth switch is grounded, the other end of the fifth switch is connected to one end of the second inductor, the other end of the second inductor is connected to one end of the sixth switch and a cathode of the second diode, the other end of the sixth switch is connected to the power supply unit, an anode of the second diode is connected to one end of the seventh switch and one end of the eighth switch, and the other end of the eighth switch is connected to the stylus tip; and
wherein the first switch, the fourth switch, the sixth switch and the seventh switch are PMOS devices, and the second switch, the third switch, the fifth switch and the eighth switch are NMOS devices.

5 . The positive and negative voltage driving circuit according to claim 4 , wherein the control module comprises an MCU and a driving module, the MCU is configured to control the driving module to output a first control signal, a second control signal, a third control signal and a fourth control signal to the switch module; wherein the first control signal is configured to control a turn-off state and a turn-on state of the first switch, the second control signal is configured to control a turn-off state and a turn-on state of the second switch and a turn-off state and a turn-on state of the third switch, the third control signal is configured to control a turn-off state and a turn-on state of the sixth switch and a turn-off state and a turn-on state of the seventh switch, the fourth control signal is configured to control a turn-off state and a turn-on state of the fifth switch, to enable the stylus tip to alternately output the positive voltage and the negative voltage when the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch and the eighth switch are alternately turned on;
wherein the control module controls the switch module in stages including a first stage, a second stage, a third stage, a fifth stage, an eighth stage, a fourth stage and a seventh stage; and wherein: in the first stage, the second switch, the third switch and the fifth switch are in the turn-on state, and the first switch, the sixth switch and the seventh switch are in the turn-off state, to initialize the positive and negative voltage driving circuit; in the second stage, the first switch, the second switch, the third switch, the fifth switch and the eighth switch are in the turn-on state, the fourth switch, the sixth switch and the seventh switch are in the turn-off state, and the power supply unit charges the first inductor; in the third stage, the first switch, the second switch, the third switch, the sixth switch and the seventh switch are in the turn-on state, the fifth switch and the eighth switch are in the turn-off state, and the power supply unit continues to charge the first inductor; in the fourth stage, the first switch, the sixth switch and the seventh switch are in the turn-on state, the second switch, the third switch, the fifth switch and the eighth switch are in the turn-off state, and the energy stored by the first inductor in the second stage is transferred to the capacitor between the stylus tip and the stylus housing; in the fifth stage, the first switch, the fifth switch, the sixth switch and the seventh switch are in the turn-on state, the second switch, the third switch and the eighth switch are in the turn-off state, and the power supply unit charges the second inductor; in the seventh stage, the second switch, the third switch, the fifth switch and the eighth switch are in the turn-on state, the first switch, the fourth switch, the sixth switch and the seventh switch are in the turn-off state, and the energy stored by the second inductor in the fifth stage is transferred to the capacitor between the stylus tip and the st

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• Yuan Guangkai
• Tang Zhi
• Shen Haiming

Classifications

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title

• H02M3/071

  adapted to generate a negative voltage output from a positive voltage source · CPC title

• H02M1/0058

  by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826) · CPC title

• G06F3/0383

  Signal control means within the pointing device · CPC title

• G06F3/03545

  Pens or stylus · CPC title