TWI719391B - Reference voltage generator of display device - Google Patents

Abstract

The present invention discloses a reference voltage generator for a display device, which includes a first supply circuit and a second supply circuit. The first supply circuit is coupled to a first output terminal of the reference voltage generator to generate a first supply voltage to the first output terminal; and the second supply circuit is coupled to the first output terminal, and the first supply voltage is fed back to the second output terminal. The supply circuit generates a second supply voltage to a second output terminal of the reference voltage generator according to the first supply voltage.

Description

Reference voltage generator for display device

The present invention relates to a reference voltage generator, especially a reference voltage generator of a display device.

The driving circuit of the display includes a timing controller, a gate driving circuit, a source driving circuit and a common driving circuit. The gate drive circuit is used to selectively drive a plurality of thin film transistors of the display. The source driving circuit is used to receive the image signal and cooperate with the operation of the gate driving circuit to drive the display to display the image. The common driving circuit generates a common voltage to the common electrode of the display. The timing controller is used to provide various timing signals and data to the gate drive circuit, the source drive circuit and the common drive circuit.

The power of the gate drive circuit, the source drive circuit and the common drive circuit is supplied by the power generation circuit. For example, the US Patent and Trademark Office Publication No. US 2017/0103724 A1, after the power generation circuit converts the input voltage to high voltage or negative voltage, it outputs the high voltage or negative voltage to the driver (or regulator), and the driver outputs high voltage or negative voltage. The common voltage of the voltage. Therefore, the withstand voltage of this driver needs to withstand a voltage-doubled power supply, which is often a high-voltage component. Furthermore, the aforementioned US patent does not reduce the current required to resist the disturbance of the source signal. That is, the driver receives the voltage-doubled power supply, so in order to resist the disturbance of the source signal, the driver (or voltage stabilizer) needs to use the voltage-doubled power supply to provide the same current as the source signal, resulting in a significant increase in overall power consumption.

In view of the above-mentioned shortcomings of the conventional technology, the present invention provides a reference voltage generator for a display device, which does not use high voltage to provide the current required for the disturbance of the source signal, so as to achieve the purpose of power saving.

The object of the present invention is to provide a reference voltage generator for a display device, which utilizes a power supply voltage to provide the current required for the disturbance of the source signal and the gate signal, so as to achieve the purpose of power saving.

The present invention discloses a reference voltage generator for a display device, which includes a first supply circuit and a second supply circuit. The first supply circuit is coupled to a first output terminal of the reference voltage generator to generate a first supply voltage to the first output terminal; and the second supply circuit is coupled to the first output terminal, and the first supply voltage is fed back to the second output terminal. The supply circuit generates a second supply voltage to a second output terminal of the reference voltage generator according to the first supply voltage.

1: The first output

2: The second output

10: Panel

20: The first supply circuit

21: Second supply circuit

22: The third supply circuit

30: Voltage divider circuit

40: control circuit

50: switching circuit

60: Comparator

62: adjustment switch

201: Positive charging circuit

202: negative charging circuit

210, OPA: operational amplifier circuit

301: The first passive component

302: second passive component

C: Capacitor

EN1: Input terminal

EN2: Input

GATE: gate signal

GND: Reference terminal

LOAD: load

S1: The first signal

S2: second signal

S3: Signal

S4: Signal

SOURCE: Source signal

SN: Signal

t1: time

t2: time

t3: time

t4: time

t5: time

t6: time

t7: time

V22: third supply voltage

V3: Voltage

V4: Voltage

V60: Adjust the signal

VC: Control signal

VCAP: Capacitor voltage

VCOM: the first supply voltage

VCOM0: second supply voltage

VDD: power supply voltage

VDIS_L: the first reference voltage

VDIS_H: second reference voltage

VN: Voltage

VOUT1: Positive voltage

VOUT2: negative voltage

VREF1: Reference voltage

VREF2: Reference voltage

VSTOP: Reference voltage

The first figure: it is the circuit diagram of the first embodiment of the reference voltage generator of the display device of the present invention; the second figure: it is the waveform diagram of the circuit diagram of the first figure; the third figure: it is the circuit diagram of the display device of the present invention The circuit diagram of the second embodiment of the reference voltage generator; the fourth diagram: it is the circuit diagram of the third embodiment of the reference voltage generator of the display device of the present invention; the fifth diagram: it is the waveform diagram of the circuit diagram of the fourth diagram; Figure 6: It is a circuit diagram of the fourth embodiment of the reference voltage generator of the display device of the present invention; and Figure 7: It is the circuit diagram of the fifth embodiment of the reference voltage generator of the display device of the present invention.

In the specification and subsequent patent applications, certain words are used to refer to specific elements. Those with ordinary knowledge in the technical field of the present invention should understand that manufacturers may use different terms to refer to the same component. The scope of this specification and subsequent patent applications does not use differences in names as a way of distinguishing elements, but uses differences in the overall technology of elements as a criterion for distinguishing. The "include" mentioned in the entire specification and subsequent patent applications is an open term, so it should be interpreted as "including but not limited to". In addition, the term "coupling" here includes any direct and indirect electrical connection means. Therefore, if it is described that a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device, or can be electrically connected to the second device indirectly through other devices or other connection means.

In order to enable your reviewer to have a further understanding and understanding of the features of the present invention and the effects achieved, embodiments and detailed descriptions are provided. The description is as follows: Please refer to the first figure, which is the display device of the present invention. The circuit diagram of the first embodiment of the reference voltage generator. As shown in the figure, the reference voltage generator of the display device includes a first supply circuit 20 and a second supply circuit 21. The first supply circuit 20 is coupled to a first output terminal 1 of the reference voltage generator, and generates a first supply voltage VCOM to the first output terminal 1. The second supply circuit 21 is coupled to the first output terminal 1, the first supply voltage VCOM is fed back to the second supply circuit 21, and a second supply voltage VCOM0 is generated according to the first supply voltage VCOM to a second output of the reference voltage generator End 2. In this way, the reference voltage generator is coupled to a capacitor C, and after the capacitor C is charged to the potential of the first supply voltage VCOM (or a preset potential) according to the first supply voltage VCOM, the reference voltage generator is based on the second supply voltage VCOM0 controls the potential of the first supply voltage VCOM. Among them, the voltage difference between the first supply voltage VCOM and the second supply voltage VCOM0 determines a capacitor voltage VCAP, the capacitor C stores the capacitor voltage VCAP, and the capacitor voltage VCAP determines a common voltage of the display device. Therefore, when the potential change of the source signal SOURCE or the gate signal GATE disturbs the potential of the common voltage (the first supply voltage VCOM), the second supply voltage VCOM0 can provide the current required to compensate the signal disturbance to adjust the capacitance voltage VCAP The level of the common voltage (the first supply voltage VCOM) is maintained.

In this way, the output of the reference voltage generator of the present invention is a stable reference voltage, that is, the first supply voltage VCOM in the first figure. The first supply voltage VCOM is coupled to a common electrode of a panel 10 and can be a common voltage of the common electrode. When the panel 10 is an electronic paper, the reference voltage generator of the present invention can be changed to multiple outputs or multiple sets of reference voltage generators can be used to stably output multiple reference voltages. The multiple reference voltages are used as multiple common electronic papers. Voltage. The pixel structure of the panel 10 is represented by a load LOAD, which is coupled to the first supply voltage VCOM, a source signal SOURCE, and a gate signal GATE.

The gate signal GATE (for example, 17V) is coupled to the scan lines of the scan panel 10 and used to scan the scan lines. When the scan lines are scanned, the source signal SOURCE (for example, 15V) is coupled to the plurality of source lines of the panel 10 and used to drive the plurality of pixels of the panel 10 to display images. The first supply voltage VCOM (for example, 15V) is generated by the first supply circuit 20 times an input voltage. A power supply voltage VDD (for example, 2.3V or 5V) in the first figure is a power supply for driving the chip. Generally, the first supply voltage VCOM is used to resist a disturbance current caused by the source signal SOURCE and the gate signal GATE, resulting in significant power consumption. However, since the potential of the power supply voltage VDD is much lower than the potential of the first supply voltage VCOM, the present invention uses the power supply voltage VDD to generate the second supply voltage VCOM0 to resist the disturbance current, and compared to the use of the first supply voltage VCOM to resist the disturbance current Significantly reduce power consumption.

Assuming that the power consumption required to provide the disturbance current with the power supply voltage VDD (for example, 2.3V) is VDD×1mA, the power consumption required to provide the disturbance current with the first supply voltage VCOM (for example, 15V) It is 15÷2.3=6.522, which is 7 times the voltage, so the power consumption increases to 7×VDD×1mA. It can be seen from the above description that the voltage level of the power supply voltage VDD is lower than the voltage level of the first supply voltage VCOM, and the output power consumption of the second supply circuit 21 is lower than the output power consumption of the first supply circuit 20. Therefore, the second supply circuit 21 receives the power supply voltage VDD, generates the second supply voltage VCOM0 according to the power supply voltage VDD and the first supply voltage VCOM, and resists the disturbance caused by the source signal SOURCE or the gate signal GATE, which can achieve the purpose of power saving. . Therefore, when the reference voltage generator supplies a positive reference voltage, as long as the power (such as VDD) received by the second supply circuit 21 is lower than the first supply voltage VCOM, the power consumption required to stabilize the reference voltage is reduced.

It can be seen from the embodiment in the first figure that the negative charging circuit 202 of the reference voltage generator can be used to provide a negative reference voltage. However, the method of generating the negative voltage VOUT2 is less efficient and consumes more power, that is, an additional capacitor is used to convert the positive voltage to the negative voltage VOUT2. In this way, because the power consumption of the negative voltage VOUT2 generation process is relatively large, when the reference voltage generator supplies the negative reference voltage, even if the power (such as VDD) received by the second supply circuit 21 is slightly higher than the first supply voltage VCOM There is still the effect of reducing the power consumption required to stabilize the reference voltage. Furthermore, the first supply circuit 20 in the first figure may include a positive charging circuit 201 but not a negative charging circuit 202, or the first supply circuit 20 may include a negative charging circuit 202 but not a positive charging circuit 201, and both All the embodiments can cooperate with the second supply circuit 21 to achieve the effect of power saving. In addition, it can be seen from the embodiment of the first figure that the first supply voltage VCOM must be generated by the first supply circuit 20 and cannot be generated by the second supply circuit 21 according to the power supply voltage VDD.

Referring to the first figure again, the first supply circuit 20 includes a positive charging circuit 201 and a negative charging circuit 202. The positive charging circuit 201 and the negative charging circuit 202 respectively receive the input voltage, and after doubling the input voltage, a positive voltage VOUT1 and a negative voltage VOUT2 are generated. The input voltage can be the power supply voltage VDD, and the positive charging circuit 201 and the negative charging circuit can receive the same or different input voltages, both of which are It is a design option. The positive charging circuit 201 and the negative charging circuit 202 can be applied to the polarity conversion of these pixels. Therefore, the positive voltage VOUT1 output by the positive charging circuit 201 supplies the power required for the positive polarity of these pixels. At this time, the first supply voltage VCOM is positive. Voltage VOUT1. The negative voltage VOUT2 output by the negative charging circuit 202 supplies the power required for the pixels to have a negative polarity. At this time, the first supply voltage VCOM is the negative voltage VOUT2.

Furthermore, the input terminals EN1 and EN2 of the positive charging circuit 201 and the negative charging circuit 202 receive a first signal S1 and a second signal S2, respectively. The first signal S1 and the second signal S2 can be generated by a timing controller, or additionally A circuit is provided to generate the first signal S1 and the second signal S2. The positive charging circuit 201 and the negative charging circuit 202 are enabled or disabled according to the first signal S1 and the second signal S2 to be in an operating state or a stopped state. The positive charging circuit 201 and the negative charging circuit 202 can be a charge pump or a boost circuit. The reference voltage generator includes a switching circuit 50, and the positive charging circuit 201 and the negative charging circuit 202 are coupled to the first output terminal 1 of the reference voltage generator and the second supply circuit 21 via the switching circuit 50. In the embodiment of the first figure, a voltage divider circuit 30 is included. The voltage divider circuit 30 includes a plurality of passive components, such as a plurality of resistors. Therefore, the positive charging circuit 201 and the negative charging circuit 202 of the first supply circuit 20 can be coupled to the second supply circuit 21 via the voltage divider circuit 30. Wherein, the switching circuit 50 includes a plurality of switching switches, and the switching switches are respectively switched on or off according to the control of the first signal S1 and the second signal S2. Furthermore, in the embodiment of the first figure, when the first signal S1 is at a high level, the reference voltage generator can be controlled to output a positive voltage VOUT1 as the first supply voltage VCOM. Conversely, when the second signal S2 is at a high level, the reference voltage generator is controlled to output the negative voltage VOUT2 as the first supply voltage VCOM. However, the first signal S1 and the second signal S2 can be set to a low level to turn on the switching switches of the switching circuit 50, and their different settings are still within the design scope of the reference voltage generator of the present invention.

The switching circuit 50 is coupled to the first supply circuit 20, the second supply circuit 21, and the voltage divider circuit 30. Therefore, the first supply voltage VCOM of the first output terminal 1 is a positive voltage VOUT1 or a negative voltage corresponding to the switching of the switching circuit 50. VOUT2. In addition, the voltage divider circuit 30 may be disposed in the second supply circuit 21, so the second supply circuit 21 receives the first supply voltage VCOM as a positive voltage VOUT1 or a negative voltage VOUT2 corresponding to the switching of the switching circuit 50. In the first figure, the voltage divider circuit 30 is coupled to the first output terminal 1, the first supply voltage VCOM of the positive voltage VOUT1 and the negative voltage VOUT2 is fed back to the voltage divider circuit 30, and the voltage divider circuit 30 divides the positive voltage The first supply voltage VCOM of VOUT1 and the negative voltage VOUT2 generates a divided voltage. Furthermore, the voltage divider circuit 30 includes a first passive element 301 and a second passive element 302. The first passive element 301 is coupled between the first output terminal 1 and a reference terminal GND, and the second passive element 302 is coupled between the power supply voltage VDD and the first output terminal 1. The reference terminal GND is a low voltage level, which is not limited to a zero voltage level or a negative voltage level.

Referring to the first figure again, the second supply circuit 21 includes an operational amplifier circuit 210. The operational amplifier circuit 210 includes a plurality of input terminals, and the input terminals respectively receive a power supply voltage VDD, a low voltage, a reference voltage VREF1, VREF2, and a divided voltage. The low voltage is lower than the power supply voltage VDD. The operational amplifier circuit 210 generates the second supply voltage VCOM0 according to the power supply voltage VDD, the reference voltage VREF1 (or VREF2) and the divided voltage, and raises the voltage level of the first supply voltage VCOM. The operational amplifier circuit 210 generates the second supply voltage VCOM0 according to the low voltage, the reference voltage VREF2 (or VREF1) and the divided voltage, and lowers the voltage level of the first supply voltage VCOM. The voltage divider circuit 30 is coupled to the first output terminal 1 and the operational amplifier circuit 210, and generates a divided voltage to the operational amplifier circuit 210 according to the first supply voltage VCOM. The operational amplifier circuit 210 is coupled to two reference voltages VREF1 and VREF2. The two reference voltages VREF1 and VREF2 can be used to compare the divided voltage of positive polarity and the divided voltage of negative polarity, respectively. Furthermore, the two reference voltages VREF1 and VREF2 are respectively transmitted to the operational amplifier circuit 210 via different switches. However, two references The voltage can be changed to a reference voltage to compare the divided voltages of positive polarity and negative polarity, which is not limited by this embodiment.

Therefore, the operational amplifier circuit 210 calculates a difference according to the divided voltage and the reference voltage VREF1 (or VREF2), and then generates the second supply voltage VCOM0 according to the difference. Therefore, the second supply voltage VCOM0 will change as the divided voltage changes, that is, the second supply voltage VCOM0 will decrease (rise) as the divided voltage rises (falls). When the voltage divider circuit 30 is disposed in the second supply circuit 21, the second supply voltage VCOM0 will drop (rise) as the first supply voltage VCOM rises (falls). Furthermore, the driving capability of the second supply circuit 21 is greater than the coupling effect of the disturbance current. Therefore, when the upper electrode of the capacitor C is charged and pulled up due to the signal disturbance, the lower electrode is discharged and the potential of the upper and lower electrodes is lowered.

Furthermore, the withstand voltage range of the operational amplifier circuit 210 is between the power supply voltage VDD and the low voltage of the reference terminal GND, rather than between the first supply voltage VCOM and the low voltage of the high or negative voltage. Therefore, the operational amplifier circuit 210 can be a medium-voltage component instead of a high-voltage component, so as to reduce component mismatch. Moreover, if the power supply capability of the first supply circuit 20 is further improved, and the current required for the signal disturbance is supplied, the overall power consumption will be greatly increased. Therefore, the reference voltage generator of the present invention adds a second supply circuit 21, and the second supply circuit 21 supplies a signal to disturb the required current according to the power supply voltage VDD. In this way, the power consumption of the second supply circuit 21 is less than the power consumption directly supplied by the first supply circuit 20, which achieves the purpose of power saving. In addition, the reference voltage generator utilizes the second supply circuit 21 to improve the instantaneous power supply capability under the power saving requirement. Therefore, after the first supply voltage VCOM is stabilized, the first supply circuit 20 only needs to provide a small current (for example, to compensate for the leakage current of the panel 10) to the panel 10 again. In this way, the flying capacitor of the first supply circuit 20 can be reduced, and when the power consumption of the flying capacitor is slow, the voltage doubling operation frequency of the first supply circuit 20 can be further reduced. In addition, at the first supply voltage VCOM After stabilization, the tiny current provided by the first supply circuit 20 is smaller than the dynamic compensation current provided by the second supply circuit 21. Among them, the compensation current is the current required to resist the signal disturbance. In other words, when the level of the first supply voltage VCOM is maintained, the output power consumption of the second supply circuit 21 is higher than the output power consumption of the first supply circuit 20.

The reference voltage generator in the first figure further includes a control circuit 40. The control circuit 40 is coupled to the second output terminal 2 and the first supply circuit 20, and controls the first supply circuit 20 to generate a positive voltage VOUT1 and a negative voltage VOUT2 according to the second supply voltage VCOM0. The control circuit 40 includes a positive input terminal (+) and a negative input terminal (-). The positive input terminal (+) and the negative input terminal (-) are respectively coupled to the switches of the switching circuit 50. The positive input terminal (+) and the negative input terminal (-) of the control circuit 40 receive a reference voltage VSTOP or a second supply voltage VCOM0 according to the switching of the switches. The control circuit 40 generates a control signal VC to the first supply circuit 20 according to the reference voltage VSTOP and the second supply voltage VCOM0. Therefore, the reference voltage generator sets the control circuit 40 to control the operation of the first supply circuit 20, and controls the level of the first supply voltage VCOM through the first supply circuit 20. The level of the reference voltage VSTOP can be set to 50% of the level of the power supply voltage VDD, or the reference voltage VSTOP can be set as a hysteresis voltage, which can modify the setting of the reference voltage VSTOP according to requirements.

When the first signal S1 controls the switch to be turned on, the first supply circuit 20 outputs a positive voltage VOUT1 to the first output terminal 1, and the first supply voltage VCOM has a positive polarity. The first supply voltage VCOM is fed back to the second supply circuit 21. The second supply circuit 21 generates a second supply voltage VCOM0 according to the first supply voltage VCOM and the power supply voltage VDD. The second supply voltage VCOM0 is the level of the power supply voltage VDD and used for Increase the level of the first supply voltage VCOM. At this time, the positive input terminal (+) of the control circuit 40 receives the reference voltage VSTOP, and the negative input terminal (-) receives the second supply voltage VCOM0. The control circuit 40 generates a low-level control signal VC because the second supply voltage VCOM0 is higher than the reference voltage VSTOP, and does not control The positive charging circuit 201 of the first supply circuit 20 stops operating. After the first supply voltage VCOM is charged to the level of the positive voltage VOUT1, the second supply circuit 21 controls the second supply voltage VCOM0 to decrease from the level of the power supply voltage VDD to the level of the reference voltage VSTOP. In this way, the control circuit 40 generates a high-level control signal VC when the second supply voltage VCOM0 is not greater than the reference voltage VSTOP, and controls the positive charging circuit 201 to stop operating.

When the second signal S2 controls the switch to be turned on, the first supply circuit 20 outputs a negative voltage VOUT2 to the first output terminal 1, and the first supply voltage VCOM has a negative polarity. The first supply voltage VCOM is fed back to the second supply circuit 21. The second supply circuit 21 generates a second supply voltage VCOM0 according to the first supply voltage VCOM and the power supply voltage VDD. The second supply voltage VCOM0 is a low voltage level and is used for pulling The level of the first supply voltage VCOM is low. At this time, the positive input terminal (+) of the control circuit 40 receives the second supply voltage VCOM0, and the negative input terminal (-) receives the reference voltage VSTOP. Since the reference voltage VSTOP is higher than the second supply voltage VCOM0, the control circuit 40 generates a low-level control signal VC, and does not control the negative charging circuit 202 of the first supply circuit 20 to stop operating. After the first supply voltage VCOM is charged to the level of the negative voltage VOUT2, the second supply circuit 21 controls the second supply voltage VCOM0 to increase from the low voltage level to the reference voltage VSTOP level. In this way, the control circuit 40 generates a high-level control signal VC when the second supply voltage VCOM0 is not less than the reference voltage VSTOP, and controls the negative charging circuit 202 to stop operating.

In addition, the control circuit 40 may include a comparator CMP, and the comparator CMP receives the power supply voltage VDD and the low voltage. In this way, the comparator CMP generates the high-level control signal VC according to the power supply voltage VDD, the second supply voltage VCOM0 and the reference voltage VSTOP. The comparator CMP generates a low-level control signal VC according to the low voltage, the second supply voltage VCOM0 and the reference voltage VSTOP.

Please refer to the first figure and the second figure together. The second figure is the waveform diagram of the circuit diagram of the first figure. As shown in the figure, at time t1, the positive charging circuit 201 of the first supply circuit 20 is enabled by the first signal S1, and the negative charging The electrical circuit 202 is disabled by the second signal S2. The output of the first supply circuit 20 is switched to the positive voltage VOUT1 and waits for the first supply voltage VCOM to be charged to the level of the positive voltage VOUT1. After the charging is in place, the second supply circuit 21 controls the second supply voltage VCOM0 to decrease to the potential of the reference voltage VSTOP. In this way, the comparator CMP of the control circuit 40 stops the voltage doubling operation of the positive charging circuit 201 (assuming it is a charge pump). At time t2, the source signal SOURCE (or gate signal GATE) has a positive polarity, so the source signal SOURCE disturbs the first supply voltage VCOM and raises (or adds a positive voltage) the potential of the capacitor voltage VCAP. In order to stabilize the potential of the first supply voltage VCOM, the second supply voltage VCOM0 is discharged to the reference terminal GND via the second supply circuit 21, and the voltage of the capacitor voltage VCAP is increased.

At time t3, the source signal SOURCE (or gate signal GATE) has a negative polarity, so the source signal SOURCE disturbs the first supply voltage VCOM and pulls down (or adds a negative voltage) to the potential of the capacitor voltage VCAP. In order to stabilize the potential of the first supply voltage VCOM, the second supply circuit 21 generates a second supply voltage VCOM0 according to the power supply voltage VDD, and charges the capacitor C to increase the potential of the first supply voltage VCOM. When the level of the second supply voltage VCOM0 is greater than the level of the reference voltage VSTOP, the voltage doubling operation of the first supply circuit 20 is started. In this way, the first supply circuit 20 can provide the current required by the capacitor C. At time t4, the output of the first supply circuit 20 switches to the negative voltage VOUT2, and waits for the first supply voltage VCOM to be charged to the level of the negative voltage VOUT2. After the charging is in place, the second supply circuit 21 controls the second supply voltage VCOM0 to increase to the potential of the reference voltage VSTOP. In this way, the comparator CMP of the control circuit 40 stops the voltage doubling operation of the negative charging circuit 202 (assuming it is a charge pump).

At time t5, the source signal SOURCE (or gate signal GATE) has a positive polarity, so the source signal SOURCE disturbs the first supply voltage VCOM and raises (or adds a positive voltage) the potential of the capacitor voltage VCAP. In order to stabilize the potential of the first supply voltage VCOM, the second supply voltage VCOM0 is discharged to the reference terminal GND via the second supply circuit 21. When the level of the second supply voltage VCOM0 is less than the reference voltage At the VSTOP level, the voltage doubling operation of the second supply circuit 21 is turned on to provide the current required by the capacitor C. At time t6, the source signal SOURCE (or gate signal GATE) has a negative polarity, so the source signal SOURCE disturbs the first supply voltage VCOM and pulls down (or adds a negative voltage) the potential of the capacitor voltage VCAP. In order to stabilize the potential of the first supply voltage VCOM, the second supply circuit 21 generates a second supply voltage VCOM0 according to the power supply voltage VDD, and charges the capacitor C to increase the potential of the first supply voltage VCOM. When the level of the second supply voltage VCOM0 is greater than the level of the reference voltage VSTOP, the voltage doubling operation of the second supply circuit 21 is stopped.

At time t7, the output of the first supply circuit 20 is switched to the positive voltage VOUT1 and waits for the first supply voltage VCOM to be charged to the level of the positive voltage VOUT1. After the charging is in place, the second supply circuit 21 controls the second supply voltage VCOM0 to decrease to the potential of the reference voltage VSTOP. In this way, the comparator CMP of the control circuit 40 stops the voltage doubling operation of the positive charging circuit 201.

Please refer to the third figure, which is a circuit diagram of the second embodiment of the reference voltage generator of the display device of the present invention. As shown in the figure, the reference voltage generator may include a third supply circuit 22. The third supply circuit 22 is coupled to the first output terminal 1 and generates a third supply voltage V22 to the first output terminal 1. When the third supply circuit 22 supplies power, the output of the second supply circuit 21 can be set to the power supply voltage VDD, a floating state or a low voltage of the reference terminal GND to prevent the operation of the third supply circuit 22 from discharging the capacitor voltage VCAP. The third supply circuit 22 can be used for the pre-charging mechanism of the panel 10 or directly set the level of the first supply voltage VCOM. Therefore, the third supply voltage V22 can be the power supply voltage VDD, the equalization voltage or the low voltage of the reference terminal GND, which can be appropriately selected. Furthermore, the third supply circuit 22 includes a plurality of switch switches, which are controlled by a plurality of signals S3, S4...SN to respectively transmit a plurality of voltages V3, V4...VN as the third supply voltage V22.

Please refer to FIG. 4, which is a circuit diagram of the third embodiment of the reference voltage generator of the display device of the present invention. As shown in the figure, between the output terminals 1 and 2 of the reference voltage generator and the capacitor C, and between the capacitor C and the panel 10, a total of four switch switches are added. That is, the switching circuit 50 adds four switching switches. In this way, the switching circuit 50 is coupled to the first supply circuit 20, the second supply circuit 21, the first output terminal 1 and the second output terminal 2. When the first supply circuit 20 generates the first supply voltage VCOM to the first output terminal 1 according to the switching of the four switches (ie, the switching circuit 50), the second supply circuit 21 generates the second supply voltage VCOM according to the switching of the four switches. The voltage VCOM0 is supplied to the second output terminal 2. When the first supply circuit 20 generates the first supply voltage VCOM to the second output terminal 2 according to the switching of the four switches, the second supply circuit 21 generates the second supply voltage VCOM0 to the first output terminal 2 according to the switching of the four switches. Output terminal 1. The four switches are also controlled by the first signal S1 and the second signal S2. Under the switching of the four switches, there is no need to discharge the voltage of the capacitor voltage VCAP and then convert it to a positive or negative voltage.

Please refer to the fifth figure, which is the waveform diagram of the circuit diagram of the fourth figure. As shown in the figure, the difference between the embodiment in the fifth figure and the embodiment in the second figure is that the capacitor voltage VCAP is positive during the period from time t4 to time t7 in the fifth diagram, while the capacitor voltage VCAP is positive during the period from time t4 to time t7 in the second diagram. The voltage VCAP has a negative polarity. Furthermore, the time t7 in the fifth graph is compared with the time t7 in the second graph. The second supply voltage VCOM0 in the fifth graph will be converted by the leakage current of the panel 10 or the source signal SOURCE (or gate signal GATE). Slowly return to the level of the reference voltage VSTOP. The rest of the technical content is similar to the embodiment in the second figure and will not be repeated.

Please refer to FIG. 6, which is a circuit diagram of the fourth embodiment of the reference voltage generator of the display device of the present invention. As shown in the figure, the sixth embodiment is based on the fifth embodiment and the third supply circuit 22 of the third embodiment is added. Therefore, the embodiment in FIG. 6 is a variation of the above-mentioned embodiment, and will not be repeated here.

Please refer to FIG. 7, which is a circuit diagram of the fifth embodiment of the reference voltage generator of the display device of the present invention. As shown in the figure, the reference voltage generator includes an adjustment circuit, and the adjustment circuit includes a comparator 60 and a plurality of switches (switching circuit 50). The two input terminals of the comparator are coupled to the switching switches, and the switches are coupled to the first signal S1 and the second signal S2. The first signal S1 and the second signal S2 control the switching of the switches to transmit the second supply voltage VCOM0, the first reference voltage VDIS_L or the second supply voltage VCOM0, and the second reference voltage VDIS_H to the two input terminals of the comparator 60. Therefore, the comparator 60 compares the second supply voltage VCOM0, the first reference voltage VDIS_L, or the second supply voltage VCOM0, and the second reference voltage VDIS_H to generate an adjustment signal V60. In an embodiment of the present invention, the second reference voltage VDIS_H is higher than the first reference voltage VDIS_L. The comparator 60 is coupled to an adjustment switch 62, so the adjustment signal V60 controls the switching of the adjustment switch 62. The adjustment switch 62 is coupled between the first output terminal 1 and the reference terminal GND. The comparator 60 is coupled to the power supply voltage VDD and the ground level of the reference terminal GND. After the adjustment circuit controls the discharge of the first supply voltage VCOM, the potential of the second supply voltage VCOM0 can be reset. Wherein, the potential of the second supply voltage VCOM0 can be reset to the level of the reference voltage or other voltage levels.

For example, when the common voltage (first supply voltage VCOM) is a positive voltage VOUT1 and the level is increased while the second supply voltage VCOM0 maintains the common voltage (first supply voltage VCOM) level, the comparator 60 compares the second supply voltage VCOM0 with The first reference voltage VDIS_L. When the second supply voltage VCOM0 is lower than the first reference voltage VDIS_L, the adjustment signal V60 is at a high level and the adjustment switch 62 is turned on. In this way, the potential of the first supply voltage VCOM is lowered, and the second supply circuit 21 controls the second supply voltage VCOM0 to be higher than the first reference voltage VDIS_L according to the feedback of the first supply voltage VCOM, which can prevent the second supply voltage VCOM0 from being too low In an embodiment of the present invention, the first reference voltage VDIS_L may be slightly higher than the ground level of the ground terminal GND. Or, when the common voltage (the first supply voltage VCOM) is a negative voltage VOUT02 and the level is pulled down (the voltage drop increases), the second supply voltage VCOM0 maintains the common voltage (the first After the level of the supply voltage VCOM), the comparator 60 compares the second supply voltage VCOM0 with the second reference voltage VDIS_H. When the second supply voltage VCOM0 is higher than the second reference voltage VDIS_H, the adjustment signal V60 is at a high level and conducts adjustment开关62。 Switch 62. In this way, the potential of the first supply voltage VCOM rises, and the second supply circuit 21 controls the second supply voltage VCOM0 to be lower than the second reference voltage VDIS_H according to the feedback of the first supply voltage VCOM, which can prevent the second supply voltage VCOM0 from being too high In an embodiment of the present invention, the second reference voltage VDIS_H may be slightly lower than the level of the power supply voltage VDD. The above two control methods can cooperate with the operation of the positive charging circuit 201 and the negative charging circuit 202, and when the level of the second supply voltage VCOM0 reaches the upper limit or the lower limit, the first supply voltage VCOM is discharged to restore the second The level of the supply voltage VCOM0. Therefore, the potential of the second supply voltage VCOM returns to a specific voltage level. The embodiment does not limit the scope of the specific voltage level.

In summary, the present invention discloses a reference voltage generator for a display device, which includes a first supply circuit and a second supply circuit. The first supply circuit is coupled to a first output terminal of the reference voltage generator to generate a first supply voltage to the first output terminal; and the second supply circuit is coupled to the first output terminal, and the first supply voltage is fed back to the second output terminal. The supply circuit generates a second supply voltage to a second output terminal of the reference voltage generator according to the first supply voltage. Furthermore, the above-mentioned embodiment illustrates that the first supply circuit 20 and the second supply circuit 21 respectively supply the power required for the output of the reference voltage generator, and generate a stable reference voltage under the demand of power saving, so as to improve the performance of the display device. Display quality.

However, the foregoing are only some of the many embodiments of the present invention, and are not used to limit the scope of implementation of the present invention. Therefore, all the structures, circuits, features and spirits described in the scope of the patent application of the present invention are listed. All equal changes and modifications should be included in the scope of the patent application of the present invention.

1‧‧‧The first output

2‧‧‧Second output

10‧‧‧Panel

20‧‧‧First supply circuit

21‧‧‧Second Supply Circuit

30‧‧‧Voltage divider circuit

40‧‧‧Control circuit

50‧‧‧Switching circuit

201‧‧‧Positive charging circuit

202‧‧‧Negative charging circuit

210, OPA‧‧‧Operational amplifier circuit

301‧‧‧The first passive component

302‧‧‧Second passive component

C‧‧‧Capacitor

EN1‧‧‧Input terminal

EN2‧‧‧Input terminal

GATE‧‧‧Gate signal

GND‧‧‧Reference terminal

LOAD‧‧‧Load

S1‧‧‧First signal

S2‧‧‧Second signal

SOURCE‧‧‧Source signal

VC‧‧‧Control signal

VCAP‧‧‧Capacitor voltage

VCOM‧‧‧First supply voltage

VCOM0‧‧‧Second supply voltage

VDD‧‧‧Power supply voltage

VOUT1‧‧‧Positive voltage

VOUT2‧‧‧Negative voltage

VREF1‧‧‧Reference voltage

VREF2‧‧‧Reference voltage

VSTOP‧‧‧Reference voltage

Claims (13)

A reference voltage generator for a display device, comprising: a first supply circuit coupled to a first output terminal of the reference voltage generator to generate a first supply voltage to the first output terminal; and a second supply A circuit coupled to the first output terminal, the first supply voltage of the first output terminal is fed back to the second supply circuit, and the second supply circuit generates a second supply voltage to the reference voltage according to the first supply voltage A second output terminal of the generator. According to the reference voltage generator of the display device described in claim 1, wherein, when the level of the first supply voltage is maintained, the output power consumption of the second supply circuit is higher than the output of the first supply circuit Power consumption. According to the reference voltage generator of the display device described in claim 1, wherein the second supply circuit receives a power supply voltage, and generates the second supply voltage according to the power supply voltage and the first supply voltage. According to the reference voltage generator of the display device described in item 3 of the scope of patent application, the power supply voltage is lower than the first supply voltage. The reference voltage generator of the display device described in the first item of the scope of patent application, wherein the reference voltage generator charges a capacitor according to the first supply voltage, the capacitor stores a capacitor voltage, and the capacitor voltage determines the display device A common voltage, and the second supply voltage maintains the level of the common voltage. According to the reference voltage generator of the display device described in item 1 of the scope of patent application, the second supply circuit includes: An operational amplifier circuit includes a plurality of input terminals. The input terminals respectively receive a power supply voltage, a low voltage, a reference voltage, and a divided voltage. The operational amplifier circuit is based on the power supply voltage, the reference voltage, and the divided voltage. The second supply voltage is generated to raise the voltage level of the first supply voltage, and the operational amplifier circuit generates the second supply voltage according to the low voltage, the reference voltage and the divided voltage, and lowers the first supply voltage The low voltage is lower than the power supply voltage. According to the reference voltage generator of the display device described in claim 6, wherein the second supply circuit includes: a voltage divider circuit coupled to the first output terminal and the operational amplifier circuit, the first supply The voltage is fed back to the voltage dividing circuit, and the divided voltage is generated to the operational amplifier circuit according to the first supply voltage. The reference voltage generator of the display device as described in the first item of the scope of patent application, which includes: a switching circuit coupled to the first supply circuit, the second supply circuit and a voltage divider circuit, the first output terminal The first supply voltage is a positive voltage or a negative voltage corresponding to the switching of the switching circuit. The reference voltage generator for a display device as described in claim 1 of the scope of patent application, which includes: a control circuit, coupled to the second output terminal and the first supply circuit, and controls the first supply according to the second supply voltage The circuit generates a positive voltage or a negative voltage. For the reference voltage generator of the display device described in item 9 of the scope of patent application, the control circuit includes a positive input terminal and a negative input terminal, the positive input terminal and the negative input terminal are respectively coupled to a plurality of switches, the The positive input terminal and the negative input terminal receive a reference voltage or the second supply voltage according to the switching of the switches, and generate a control signal to the first supply circuit according to the reference voltage and the second supply voltage. The reference voltage generator of the display device as described in item 1 of the scope of patent application includes: A third supply circuit is coupled to the first output terminal, and when a third supply voltage is generated to the first output terminal, the output of the second supply circuit is in a floating state. The reference voltage generator of the display device as described in the scope of the patent application, which includes: a switching circuit coupled to the first supply circuit, the second supply circuit, the first output terminal, and the second output terminal When the first supply circuit generates the first supply voltage to the first output terminal according to the switching of the switching circuit, the second supply circuit generates the second supply voltage to the second output according to the switching of the switching circuit When the first supply circuit generates the first supply voltage to the second output terminal according to the switching of the switching circuit, the second supply circuit generates the second supply voltage to the first output terminal according to the switching of the switching circuit. The output terminal. The reference voltage generator of the display device described in the first item of the scope of patent application includes: an adjustment circuit coupled to the second output terminal to receive the second supply voltage, and to receive a first reference voltage or a first reference voltage Two reference voltages, generating an adjustment signal according to the second supply voltage, the first reference voltage or the second supply voltage, and the second reference voltage; and an adjustment switch, coupled to the adjustment circuit and to the first Between an output terminal and a reference terminal, the adjustment signal controls the adjustment switch to turn on to lower or increase the potential of the first supply voltage; wherein the second supply circuit controls the first supply voltage according to the feedback of the first supply voltage The potential of the second supply voltage rises or falls.

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