TWI413084B - Liquid crystal display power supplying circuit - Google Patents

Abstract

Under a sleep mode of a display, a liquid crystal display power supplying circuit prohibits power from a liquid crystal display power, and proceeds supplying power with a motherboard, which supplies power all the time, instead. Therefore, power of the liquid crystal display power under the sleep mode of the display is replaced by retrieving the power supplied from the motherboard instead, so that unnecessary power consumption of the liquid crystal display power under the sleep mode is prevented.

Description

Liquid crystal display power supply circuit

The present invention discloses a display power supply circuit, and more particularly to a display power supply circuit that reduces power consumption.

A typical liquid crystal display saves power consumption by entering a sleep mode, and supplies a power supply of the liquid crystal display in a normal operation mode and a sleep mode with a single display power supply. The components of the liquid crystal display that need to be supplied with power mainly include a display panel, a microprocessor and a computing integrated circuit; and the potential of the display power supply is about 5 volts, and the power required by the display panel is about 5 volts, and the power required by the microprocessor It is about 3.3 volts, and the power required to calculate the integrated circuit is about 1.8 volts.

Please refer to FIG. 1 , which is a schematic diagram of a general liquid crystal display power supply circuit 100 . As shown in FIG. 1 , the liquid crystal display power supply circuit 100 includes a liquid crystal display power supply 110 , a first power supply unit 150 , a second power supply unit 160 , a first filter module 170 , a second filter module 180 , and A diode D120. The liquid crystal display power supply circuit 100 mainly supplies the power supply VO1 (about 5 volts) directly outputted through the liquid crystal display power supply 110 to directly supply the required power of the display panel 120, and the power supply VO2 generated by the first power supply unit 150 (about 3.3). The volts are provided to provide the required power to the microprocessor 130 and to provide the required power to the integrated circuit 140 through the power source VO3 (about 1.8 volts) generated by the second power supply unit 160. When the display needs to enter the sleep mode, the microprocessor 130 will send a signal to notify the display panel 120 and the computing integrated circuit 140 to be turned off, and turn off most of its functions to maintain the minimum operable function to stop respectively. Receiving power supplies VO1, VO2, VO3; conversely, when the display needs to enter the normal operating mode from sleep state, The microprocessor 130 sends a signal to notify the display panel 120 and the arithmetic integrated circuit 140 to continue to receive the power sources VO1, VO2, and VO3, respectively. However, when the display enters the sleep mode, there is still a relatively small current flowing through the diode D120, causing the liquid crystal display power supply 110 to be in an inefficient operating state and still producing power consumption that cannot be ignored.

The invention discloses a liquid crystal display power supply circuit. The liquid crystal display power supply circuit comprises a motherboard switch circuit, a liquid crystal display power supply, a power switch circuit and a first power supply unit. One of the input terminals of the motherboard switch circuit is coupled to a power output of a motherboard. An input end of the power switch circuit is coupled to the liquid crystal display power supply. The first power supply unit is coupled to an output end of the motherboard switch circuit, an output end of the power switch circuit, and a microprocessor for supplying power to the motherboard or the power of the liquid crystal display. microprocessor.

The liquid crystal display power supply circuit disclosed in the embodiment of the present invention isolates the power supply of the liquid crystal display power supply in the sleep mode of the display, and changes the power supply in the sleep mode by the motherboard that needs to be powered at any time, so that the liquid crystal display power supply is on the display. In the sleep mode, the power that would otherwise be consumed but not consumed will be passed on to the motherboard that needs to be powered at any time, and the unnecessary power consumption of the LCD monitor power supply in the sleep mode is saved.

In order to solve the problem that there is still power consumption that cannot be ignored in the sleep mode described in the prior art, an embodiment of the present invention discloses a method for reducing power consumption. Display power supply circuit. The disclosed display power supply circuit mainly cuts off the power output of the liquid crystal display power supply when the display enters the sleep mode, and separately supplies the power supply of the display in the sleep mode by using the motherboard of the display. In this way, since the motherboard of the display itself provides power at any time, this feature can be used to pass the power consumed by the power supply of the liquid crystal display in the prior art to the output power of the motherboard which would otherwise be consumed, thereby preventing the liquid crystal. The display power consumes excess power.

Please refer to FIG. 2 and FIG. 3 , which are schematic diagrams of a liquid crystal display power supply circuit 200 according to the first and second embodiments of the present invention. FIG. 2 is a liquid crystal display power supply circuit 200 according to the first embodiment. FIG. 3 is a schematic diagram of the liquid crystal display 200 disclosed in the second embodiment.

As shown in FIG. 2, in the first embodiment, the liquid crystal display power supply circuit 200 includes a motherboard switch circuit 230, a power switch circuit 240, and the liquid crystal display power supply 110 and the first power supply unit 150 shown in FIG. . The first power supply unit 150 is configured to supply the power of a motherboard or the power of the liquid crystal display power supply 110 to the microprocessor 130 through the motherboard switch circuit 230 or the power switch circuit 240. When the display enters the normal operation mode, the liquid crystal display power supply circuit 200 turns off the motherboard switch circuit 230 and turns on the power switch circuit 240, so that the power of the motherboard cannot be supplied to the first power supply unit 150 through the motherboard switch circuit 230, and The power of the liquid crystal display power supply 110 can be supplied to the microprocessor 130 through the power switch circuit 240. Similarly, when the display enters the sleep mode, the liquid crystal display power supply circuit 200 turns on the motherboard switch circuit 230 and turns off the power switch circuit 240, so that the power of the motherboard can be supplied to the first power supply unit 150 through the motherboard switch circuit 230. The power of the liquid crystal display power source 110 cannot be supplied to the first power supply unit 150 through the power switch circuit 240.

As shown in FIG. 3, in the second embodiment, the liquid crystal display power supply circuit 200 is coupled to a motherboard 210, and is used to provide the microprocessor 130, the display panel 120, and the arithmetic integrated circuit 140 shown in FIG. Three different potentials for the power supply. As shown in FIG. 3, the liquid crystal display power supply circuit 200 includes a motherboard switch circuit 230, a power switch circuit 240, and a liquid crystal display power supply 110 shown in FIG. 1, a first power supply unit 150, a second power supply unit 160, and a first The filter module 170 and the second filter module 180.

In the normal operation mode of the display, the liquid crystal display power supply circuit 200 receives the power supply VO1 from the liquid crystal display power supply 110 for the display panel 120 to operate, and turns on the power switch circuit 240, so that the power supply VO1 can be input to the first power supply unit 150; At this time, the power supply VOS located at the input end of the first power supply unit 150 is generated according to the power source VO1, and the liquid crystal display power supply circuit 200 turns off the motherboard switch circuit 230 to isolate one of the motherboard output powers VOM generated by the motherboard 210. Supply. In this way, the first power supply unit 150 converts the power supply VOS into the power supply VO2, and supplies it to the microprocessor 130 for operation, and the second power supply unit 160 generates the power supply VO3 according to the power supply VO2, and supplies it to the arithmetic integrated circuit 140.

In the sleep mode of the display, the microprocessor 130 generates a control signal to turn off the integrated integrated circuit 140 and the display panel 120, so that the display panel 120 does not consume the power supply VO1 supplied from the liquid crystal display power supply 110. Moreover, the liquid crystal display power supply circuit 200 turns off the power switch circuit 240 and turns on the motherboard switch circuit 230, so that the power supply VOS received by the first power supply unit 150 is based on the motherboard output power VOM provided by the motherboard 210. It is generated instead of the power source VO1 provided by the liquid crystal display power supply 110. At this time, the liquid crystal display power source 110 is in a state in which no power is consumed at all, because the path of its power consumption is completely blocked to achieve the purpose of saving the liquid crystal display power source 110 in the sleep mode.

Please refer to FIG. 4 , which is a schematic diagram of a liquid crystal display power supply circuit 200 of FIG. 2 according to a third embodiment of the present invention. FIG. 4 primarily discloses an embodiment of the power switch circuit 240 and the motherboard switch circuit 230 shown in FIG. 2. As shown in FIG. 4, the motherboard switching circuit 230 includes a first diode D103, a resistor R103, a Zenar Diode ZD102, and a capacitor C100. The first end of the first diode D103 is coupled to one of the power supply outputs of the motherboard 210 to receive the output power VOM of the motherboard. The first end of the resistor R103 is coupled to one of the second ends of the first diode D103, and the second end of the resistor R103 is coupled to one of the power supply inputs of the first power supply unit 150. The first end of the Zener diode ZD102 is coupled to the power output end of the motherboard 210, and the second end of the Zener diode ZD102 is grounded. The first capacitor C100 is connected in parallel to the Zener diode ZD102. The power switch circuit 240 includes a second diode D101 and a third diode D102. The first end of the second diode D101 is coupled to the liquid crystal display power supply 110. The first end of the third diode D102 is coupled to the second end of the second diode D101, and the second end of the third diode D102 is coupled to the first power supply unit 150. The power input. The Zener diode ZD102 and the capacitor C100 are mainly used to filter out the noise contained in the VOM of the motherboard output power generated by the motherboard 210.

The operation of the motherboard switching circuit 230 and the power switch circuit 240 shown in FIG. 4 is described below.

When the display is in the normal operation mode, the second and third diodes D101 and D102 are positively biased and thus turned on due to the power supply VO1 provided by the liquid crystal display power supply 110, so that the power switch circuit 240 is turned on; Because the display is in the normal operation mode, the motherboard 210 generates a large current, so that when the motherboard output power VOM is transmitted through the first diode D103 and the resistor R103, a greater than one diode is generated on the resistor R103. Bucker produced by the body; The voltage drop across the diode is a fixed value. In other words, the power supply VO1 will only encounter the fixed voltage drop of the two diodes brought by the second and third diodes D101 and D102, but the power supply VOS In addition to the fixed voltage drop of the single diode brought by the first diode D103, the fixed voltage drop of the resistor R103 due to the larger current of the motherboard 210 is greater than that of the single diode. A voltage drop, so the first diode D103 is in a reverse bias state at this time, so that the motherboard output power VOM provided by the motherboard 210 is isolated from the voltage input terminal of the first power supply unit 150. In summary, the power supply VOS received by the first power supply unit 150 at this time is only provided by the power supply VO1 provided by the liquid crystal display power supply 110.

When the display is in the sleep mode, the motherboard 210 generates a small current, so the voltage drop generated on the resistor R103 is smaller than the fixed voltage drop of the single diode; in other words, the motherboard output power VOM is encountered at this time. The voltage drop only includes a fixed voltage drop of the single diode on the first diode D103 and a voltage drop on the resistor R103 that is less than the fixed voltage drop of the single diode. Since the voltage drop encountered by the power supply VO1 provided by the liquid crystal display power supply 110 is still a fixed voltage drop brought by the two diodes D101 and D102, the second and third diodes D101 and D102 are in the opposite state. The bias state, and the first diode D103 is in a forward state, such that the power switch circuit 240 is turned off and the motherboard switch circuit 230 is turned on. In this way, in the sleep mode of the display, the power supply VOS received by the first power supply unit 150 is generated according to the motherboard output power VOM provided by the motherboard 210.

FIG. 5 is a schematic diagram of a liquid crystal display power supply circuit 200 of FIG. 2 according to a fourth embodiment of the present invention, and FIG. 5 mainly discloses a power switch circuit 240 and a motherboard in the fourth embodiment. A detailed implementation of the switch circuit 230. As shown in FIG. 5, the motherboard switching circuit 230 includes an N-type MOS transistor Q1, a first resistor R203, and a second resistor R151. Power switch circuit 240 The system includes a diode D201. A source and a gate of the N-type MOS transistor Q1 are coupled to the power output end of the motherboard 210 to receive the output power VOM of the motherboard. The first end of the first resistor R203 is coupled to one of the drains of the N-type MOS transistor Q1, and the second end of the first resistor R203 is coupled to the voltage input terminal of the first power supply unit 150. . The first end of one of the second resistors R151 is coupled to one of the bases of the N-type MOS transistor Q1, and the second end of the second resistor R151 is grounded. The first end of the diode D201 is coupled to the liquid crystal display power supply 110, and the second end of the diode D201 is coupled to the voltage input end of the first power supply unit 150. The second resistor R151 is used to adjust the bias current of the N-type MOS transistor Q1.

The operation of the power switch circuit 240 and the motherboard switch circuit 230 shown in FIG. 5 is as follows.

When the display enters the normal operation mode, the motherboard 210 generates a large current, so that the motherboard output power VOM encounters a voltage drop greater than the single diode fixed voltage drop on the first resistor R203 (assuming N type) The voltage drop across the gold-oxide semi-transistor Q1 is negligible, and the power supply VO1 provided by the liquid crystal display power supply 110 encounters a fixed voltage drop of the single diode on the diode D201, so the diode D201 is at this time Conversely, the N-type MOS transistor Q1 is turned off by the reverse bias. At this time, the power source VOS received by the first power supply unit 150 is generated according to the power source VO1 provided by the liquid crystal display power source 110, and is not generated according to the motherboard output power source VOM provided by the motherboard 210.

When the display enters the sleep mode, the motherboard 210 generates a small current, so that the motherboard output power VOM will encounter a voltage drop lower than the single diode fixed voltage drop on the first resistor R203, and the liquid crystal display power supply The power supply VO1 provided by 110 still only encounters the fixed voltage drop of the single diode on the diode D201, so At this time, the diode D201 is reverse biased, and the N-type MOS transistor Q1 is turned on by a positive bias. At this time, the power supply VOS received by the first power supply unit 150 is generated according to the motherboard output power VOM provided by the motherboard 210, and is not generated according to the power supply VO1 provided by the liquid crystal display power supply 110.

The embodiment of the present invention further discloses a liquid crystal display power supply circuit for switching power supply of a liquid crystal display or a motherboard by actively switching one of a normal operation mode and a sleep mode of a display, wherein the liquid crystal display power supply circuit comprises a liquid crystal The display power supply also needs to operate with the control signal to achieve the mechanism of switching the power of the liquid crystal display or the motherboard to supply power. Referring to FIG. 6 and FIG. 7 , FIG. 6 and FIG. 7 are schematic diagrams of a liquid crystal display power supply circuit 500 according to a fifth embodiment of the present invention, and FIG. 6 mainly discloses a power switch circuit in the fifth embodiment. A detailed implementation of the 540 and motherboard switch circuit 530, and FIG. 7 primarily discloses an embodiment of a liquid crystal display power supply 410 in the fifth embodiment. In addition, the liquid crystal display power supply circuit 500 shown in FIG. 6 and the liquid crystal display power supply 410 shown in FIG. 7 all need to be controlled by a control signal ON/OFF to trigger the switching power supply; the control signal ON/OFF is normal in the display. The operating mode is high and the control signal ON/OFF is low during the sleep mode of the display.

As shown in FIG. 6, the liquid crystal display power supply circuit 500 includes first and second power supply units 150 and 160 and corresponding first and second filter modules 170 and 180, and further includes a motherboard switch circuit 530. The power switch circuit 540 and the liquid crystal display power source 410. The motherboard switching circuit 530 includes a first npn-type bipolar junction transistor (BJT) Q303, a second npn-type bipolar junction transistor Q302, and a first diode D302. A capacitor C313 and a resistor R356, and the power switch circuit 240 includes a second diode D301. The collector of the first npn-type bipolar junction transistor Q303 is coupled to the battery of the motherboard 210 The source output terminal receives the output power VOM of the motherboard, and the base of the first npn-type dual-carrier junction transistor Q303 is coupled to a control signal ON/OFF to correspond to the difference of the control signal ON/OFF ( That is, the display sleep mode is different from the normal operation mode to change its on state. The collector of the second npn-type bipolar junction transistor Q302 is coupled to the base of the first npn-type bipolar junction transistor Q303, and the second npn-type bipolar junction transistor Q302 is emitted. The pole is grounded. The first end of the first diode D302 is coupled to the emitter of the first npn-type bipolar junction transistor Q303, and the second end of the first diode D302 is coupled to the first power source. The voltage input of the supply unit 150. The first end of the resistor R356 is coupled to the collector of the first npn-type bipolar junction transistor Q303, and the second end of the resistor R356 is coupled to the first npn-type bipolar junction transistor. The base of Q303. The first end of the capacitor C313 is coupled to the second end of the first diode D302, and the second end of the capacitor C313 is coupled to the emitter of the second npn-type bipolar transistor Q302. The first end of the second diode D301 is coupled to the liquid crystal display power supply 110 to receive the power supply VO1, and the second end of the second diode D301 is coupled to the first power supply unit 150.

As shown in FIG. 7, the liquid crystal display power supply 410 includes a first switch module 460, a first power conversion module 430, a second switch module 480, a power supply unit 450, and a second power conversion module. 420. The input end of the first switch module 460 is coupled to the power output end of the motherboard 210, that is, the power supply PC5V shown in FIG. 6, to receive the power supply PC5V from the motherboard 210. The first switch module 460 is configured to determine whether to generate a power source VP1 according to the power source PC5V according to the control signal ON/OFF, that is, whether to generate the power source VP1 according to whether the display system is in the sleep mode or the normal operation mode; in other words, the first switch The module 460 is a switch that determines whether or not to output the power source VP1. An input end of the first power conversion module 430 is coupled to an output end of the first switch module 460. When the first power conversion module 430 receives a high When the potential power source VP1 generates a positive potential difference between the input terminal S1 of the first power conversion module 430 and the grounded input terminal S2, the output terminal S3 of the first power conversion module 430 and a grounded input terminal S4 will be turned on. The input end of the second switch module 480 is coupled to the output end S3 of the first power conversion module 430, and the second switch module 480 is additionally connected to the DC power supply VDD. The second switch module 480 is based on whether the output terminals S3 and S4 of the first power conversion module 430 are turned on, and generates a power source VP3 according to the DC power source VDD. In other words, the second switch module 480 determines whether The switch of the output power source VP3; in an embodiment of the invention, a transistor can be disposed between the output terminals S3 and S4, and the electro-crystal system controls whether the conduction is based on whether there is a potential difference between the input terminals S1 and S2, An on current between the output terminals S3, S4 is generated. One of the power supply unit 450 is connected to one of the output terminals of the second switch module 480. When the power supply VP3 received by the switch control terminal Power is at a high potential, the power supply unit 450 supplies a power supply VCCO. When the power supply VP3 received by the switch control terminal Power is at a low potential, the power supply unit 450 does not supply the power supply VCCO. An input end of the second power conversion module 420 is coupled to an output end of the power supply unit 450, and an output end of the second power conversion module 420 is coupled to the liquid crystal display power supply 410 of FIG. The output terminal, and the second power conversion module 420 converts the power source VCCO into the power source VCC5V shown in FIG. 6 to output the power source VCC5V to the output end of the liquid crystal display power source 410 and supplies it to the power switch circuit 540.

The first switch module 460 includes a pnp type bipolar junction transistor Q801 and a resistor R847. An emitter of the pnp type bipolar junction transistor Q801 is coupled to the power output end of the motherboard 210 to receive the power supply PC5V, and a base of the pnp type dual carrier junction transistor Q801 is coupled to the control. Signal ON/OFF. The first end of the resistor R847 is coupled to the collector of the pnp type bipolar junction transistor Q801, and is electrically The second end of the resistor R847 is coupled to the input end S1 of the first power conversion module 430. The second switch module 480 includes an npn-type bipolar junction transistor Q802 and two resistors R804 and R805. One of the collectors of the npn-type bipolar junction transistor Q802 is coupled to the DC power supply VDD, and one of the emitters of the npn-type bipolar junction transistor Q802 is coupled to the switching control terminal of the power supply unit 450. . The first end of the resistor R804 is coupled to the output end S3 of the first power conversion module 430, and the second end of the resistor R804 is coupled to one of the bases of the npn-type bipolar junction transistor Q802. The first end of the resistor R805 is coupled to the second end of the resistor R804, and the second end of the resistor R805 is coupled to the collector of the npn-type bipolar junction transistor Q802.

The operation mode of the power switch circuit 540 and the motherboard switch circuit 530 shown in FIG. 6 is explained in conjunction with the liquid crystal display power supply 410 shown in FIG. When the display enters the normal operation mode, the control signal ON/OFF is a high potential signal, so that the second npn type double carrier junction transistor Q302 is turned on, and the first npn type double carrier junction transistor Q303 will The on-current of the second npn-type bipolar junction transistor Q302 is turned off and its base potential is turned off. As a result, the remaining potential of the power supply PC5V to the input end of the first power supply unit 150 is lower than the remaining potential of the power supply VCC5V to the input end of the first power supply unit 150, so that the power supply VOS is relative to the first two poles. The body D302 generates a reverse bias so that the power supply PC5V provided by the motherboard 210 is to be isolated from the first power supply unit 150, and the power supply VCC5V supplied from the liquid crystal display power supply 410 transmits the power supply VOS through the second diode D301. It is supplied to the first power supply unit 150. At the same time, in the liquid crystal display power supply 410, since the control signal ON/OFF is high, the pnp type dual-carrier junction transistor Q801 is turned off, and thus the power supply VP1 shown in FIG. 7 cannot be generated. come out. Since the first power conversion module 430 does not receive the power supply VP1, the output terminals S3 and S4 of the first power conversion module 430 are not guided. Therefore, the current is generated; thus, the npn bipolar junction transistor Q802 does not pull down the potential of the base due to the current between the output terminals S3 and S4, so that the npn bipolar junction transistor Q802 is presented. The state is turned on and the power supply VP3 is at a high potential. After receiving the power supply VP3 at a high potential, the power supply unit 450 supplies the power supply VCCO to the second power conversion module 420, and finally generates the power supply VCC5V, and supplies the power supply VCC5V to the power supply shown in FIG. 6. Power switch circuit 540.

When the display enters the sleep mode, the control signal ON/OFF will be at a low potential, so that the second npn-type bipolar junction transistor Q302 is turned off, and the first npn-type bipolar junction transistor Q303 will be based on the base. The pole potential is turned on without being pulled low. In this way, since the residual potential when the power source PC5V is transmitted to the first power supply unit 150 is higher than the residual potential when the power source VCC5V is transmitted to the first power supply unit 150, the power supply VOS generates a reverse bias to the second diode D301. The power supply VCC5V supplied from the liquid crystal display power supply 410 is isolated from the first power supply unit 150, and the power supply VOB supplied from the motherboard 210 is used to generate the power supply VOS and supplied to the first power supply unit 150. In the liquid crystal display power supply 410, the pnp type dual-carrier junction transistor Q801 is turned on by the low-level control signal ON/OFF of the base thereof, thereby causing the first switching module 460 to be in the first power conversion mode. A high potential power supply VP1 is developed at input S1 of group 430. The first power conversion module 430 turns on between the output terminals S3 and S4 of the first power conversion module 430 according to the high-potential power source VP1. In the second switch module 480, the base of the npn-type bipolar junction transistor Q802 is pulled low due to the conduction current between the output terminals S3 and S4, and thus the npn-type dual carrier junction is electrically The crystal Q802 is turned off, so the power supply VP3 outputted by the second switching module Q802 is low at this time. After the switch control terminal Power of the power supply unit 450 receives the low-level power supply VP3, the power supply VCCO is stopped, because The second power conversion module 420 is also unable to generate the power source VCC5V, so that the liquid crystal display power source 410 in FIG. 6 cannot supply the power source VCC5V to the power switch circuit 540.

In FIG. 6 and FIG. 7, the control signal ON/OFF is actively activated according to the normal operation mode of the display and the power source used in the sleep mode, except that the power supply to be isolated can be reverse biased as in the previous embodiments. The manner of isolation from the power supply path further ensures power consumption of the liquid crystal display power supply circuit 500 in the sleep mode by directly turning off the power supply of the liquid crystal display power supply 410.

The liquid crystal display power supply circuit disclosed in the embodiment of the present invention isolates the power supply of the liquid crystal display power supply in the sleep mode of the display, and replaces the power supply in the sleep mode by the motherboard that needs to be powered at any time. In this way, the power of the liquid crystal display will be consumed in the sleep mode of the display, but the power that does not need to be consumed will be transferred to the motherboard that needs to be powered at any time, and the power of the liquid crystal display in the sleep mode is saved. Necessary power consumption.

While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The patent protection scope of the invention is subject to the definition of the scope of the patent application attached to the specification.

100, 200, 500‧‧‧ liquid crystal display power supply circuit

110,410‧‧‧LCD power supply

120‧‧‧ display panel

130‧‧‧Microprocessor

140‧‧‧Computed integrated circuit

150, 160, 450‧‧‧ power supply unit

170, 180‧‧‧ Filter Module

210‧‧‧ motherboard

230, 530‧‧‧ motherboard switch circuit

240, 540‧‧‧ power switch circuit

420, 430‧‧‧ power conversion module

460, 480‧‧‧ switch module

D101, D102, D103, D201, D301, D302‧‧‧ diode

ZD102‧‧‧Zina diode

C100, C313‧‧‧ capacitor

Q1, Q302, Q303, Q801, Q802‧‧‧O crystal

R151, R203, R356, R847, R805, R804‧‧‧resistance

FIG. 1 is a schematic diagram of a power supply circuit of a general liquid crystal display.

FIG. 2 and FIG. 3 are schematic diagrams showing the power supply circuit of the liquid crystal display according to the first and second embodiments of the present invention, wherein the liquid crystal display power supply circuit is coupled to the motherboard and used to provide the microprocessor shown in FIG. The power supply of the display panel and the three different potentials of the integrated circuit.

4 and FIG. 5 are schematic diagrams showing the power supply circuit of the liquid crystal display device of FIG. 2 according to the third and fourth embodiments of the present invention.

FIG. 6 and FIG. 7 are schematic diagrams showing a power supply circuit of a liquid crystal display according to a fifth embodiment of the present invention, wherein the power supply circuit of the liquid crystal display shown in FIG. 6 and the power supply of the liquid crystal display shown in FIG. 7 are controlled by a control signal. To trigger the mechanism of switching power.

200‧‧‧LCD display power supply circuit

110‧‧‧LCD power supply

120‧‧‧ display panel

130‧‧‧Microprocessor

140‧‧‧Computed integrated circuit

150, 160‧‧‧Power supply unit

170, 180‧‧‧ Filter Module

210‧‧‧ motherboard

230‧‧‧ motherboard switch circuit

240‧‧‧Power switch circuit

Claims (18)

A liquid crystal display power supply circuit comprises: a motherboard switching circuit, wherein an input end is coupled to a power output end of a motherboard; a liquid crystal display power supply; and a power switch circuit, an input end of which is coupled to the a power supply unit of the liquid crystal display; and a first power supply unit coupled to an output end of the switch circuit of the motherboard, an output end of the power switch circuit, and a microprocessor for powering the motherboard or the liquid crystal display The power is supplied to the microprocessor. The liquid crystal display power supply circuit of claim 1, wherein when a display enters a normal operation mode, the motherboard switch circuit is turned off, and the power switch circuit is turned on, so that the liquid crystal display power supply is A power source is supplied to the first power supply unit through the power switch circuit. The liquid crystal display power supply circuit of claim 1, wherein when a display enters a sleep mode, the motherboard switch circuit is turned on, and the power switch circuit is turned off, so that one of the motherboards of the motherboard The output power source is supplied to the first power supply unit through the motherboard switch circuit. The liquid crystal display power supply circuit of claim 1, wherein the motherboard switching circuit comprises: a first diode, a first end of which is coupled to the power output end of the motherboard; and And a first end of the resistor is coupled to the second end of the first diode, and the second end of the resistor is coupled to the first power supply unit. The liquid crystal display power supply circuit of claim 4, wherein the motherboard switching circuit further comprises: a Zenar Diode, wherein a first end is coupled to the motherboard a power output end, and a second end of the Zener diode is grounded; and a first capacitor is connected in parallel to the Zener diode. The liquid crystal display power supply circuit of claim 4, wherein the power switch circuit comprises: a second diode, a first end of which is coupled to the liquid crystal display power supply; and a third The first end of the second diode is coupled to the second end of the second diode, and the second end of the third diode is coupled to the first power supply unit. The liquid crystal display power supply circuit of claim 1, wherein the motherboard switching circuit comprises: an N-type MOS transistor, wherein a source and a gate are coupled to the motherboard The first output of the first resistor is coupled to one of the N-type MOS transistors, and the second end of the first resistor is coupled to the first Power supply unit. The liquid crystal display power supply circuit of claim 7, wherein the motherboard switching circuit further comprises: a second resistor, a first end of which is coupled to one of the N-type MOS transistors And a second end of the second resistor is grounded. The liquid crystal display power supply circuit of claim 7, wherein The power switch circuit includes a fourth diode, a first end of which is coupled to the liquid crystal display power source, and a second end of the fourth diode is coupled to the first power supply unit . The liquid crystal display power supply circuit of claim 1, wherein the motherboard switching circuit comprises: a first npn-type dual-carrier junction transistor, wherein the collector is coupled to the motherboard a power supply output end, and a base of the first npn-type bipolar-substrate transistor is coupled to a control signal; a second npn-type dual-carrier junction transistor, the collector of which is coupled to the first An anode of the npn-type bipolar junction transistor, and an emitter of the second npn-type bipolar junction transistor is grounded; and a fifth diode, a first end of which is coupled to An emitter of the first npn-type bipolar junction transistor, and a second end of the fifth diode is coupled to the first power supply unit; wherein the display system includes one of the display power supply circuits When entering the sleep mode, the potential of the control signal is a low potential. The liquid crystal display power supply circuit of claim 10, wherein the motherboard switching circuit further comprises: a resistor, a first end of which is coupled to the first npn type dual carrier junction transistor The collector is coupled to the base of the first npn-type bipolar junction transistor; a capacitor having a first end coupled to the fifth The second end of the capacitor is coupled to the emitter of the second npn-type bipolar transistor. The liquid crystal display power supply circuit of claim 10, wherein The power switch circuit includes a sixth diode, a first end of which is coupled to the liquid crystal display power source, and a second end of the sixth diode is coupled to the first power supply unit . The liquid crystal display power supply circuit of claim 10, wherein the liquid crystal display power supply comprises: a first switch module, wherein an input end is coupled to the power output end of the motherboard, the first a switch module is configured to determine whether to generate a second power source according to the first power source generated by the motherboard according to the control signal; a first power conversion module, an input end of which is coupled to the first An output terminal of the switch module, the first power conversion module is configured to conduct current between a first output end and a second output end according to whether the second power source is at a high potential; a second switch mode An input end is coupled to the first output end of the first power conversion module, and the second switch module is configured to be configured according to the first output end of the first power conversion module A second power supply is generated between the two output terminals; a second power supply unit has a switch control end coupled to an output end of the second switch module, the second power supply unit According to whether the third power source is And generating a fourth power source at a high potential; and a second power conversion module, wherein an input end is coupled to an output end of the second power supply unit, and an output end of the second power conversion module Is coupled to the output end of the power switch circuit, and the second power conversion module converts the fourth power source into a fifth power source, and outputs the fifth power source to the output end of the power switch circuit . The liquid crystal display power supply circuit of claim 13, wherein the first switch module comprises: a pnp type dual-carrier junction transistor, wherein an emitter is coupled to the power output of the motherboard, and a base of the pnp-type dual-carrier transistor is coupled to the control signal And a first resistor coupled to the collector of the pnp-type bipolar junction transistor, and the second end of the first resistor is coupled to the first power conversion mode group. The liquid crystal display power supply circuit of claim 13, wherein the second switch module comprises: a third npn type double carrier junction transistor, wherein a collector is coupled to the DC power supply And an emitter of the third npn-type bipolar junction transistor is coupled to the switch control end of the second power supply unit; a second resistor coupled to the first end of the second resistor a first output end of the power conversion module, and a second end of the second resistor is coupled to one of the bases of the third npn-type bipolar junction transistor; and a third resistor A first end is coupled to the second end of the second resistor, and a second end of the third resistor is coupled to the collector of the third npn-type bipolar junction transistor. The liquid crystal display power supply circuit of claim 1, further comprising: a first filter module for filtering noise contained in one of the power sources received by the power supply unit. The liquid crystal display power supply circuit of claim 1, wherein a display panel is coupled to the liquid crystal display power supply, the microprocessor is coupled to the first power supply unit to receive the first power supply. The unit provides one of the first output power sources. The liquid crystal display power supply circuit as described in claim 17 of the patent application, further comprising: a second power supply unit for converting the first output power to a second output power for supplying to one of the liquid crystal display computing circuits; and a second filtering module for filtering the first The noise in the second output power source processed by the two power supply units.