Negative voltage output circuit and display device

Abstract

The utility model discloses a kind of negative pressure output circuit and display equipment, the negative pressure output circuit includes enabling module and negative pressure conversion module;The enabling module is connected with the control module of the display equipment, for receiving the enabling signal of the control module;One end of the negative pressure conversion module is connected with the enabling module and power supply respectively, and the other end of the negative pressure conversion module is connected with the display screen of the display equipment, for converting positive pressure input into negative pressure output.The utility model can avoid external hanging MOS tube, so as to reduce cost and improve PCB layout.

Description

Technical Field

[0001] This utility model relates to the field of display system technology, and in particular to a negative pressure output circuit and display device. Background Technology

[0002] OLED displays require both positive and negative voltage power supplies during operation. Currently, the common approach is an integrated solution, which can integrate components to a certain extent. However, as screen sizes continue to increase, the operating current also increases accordingly, necessitating the use of high-voltage MOSFETs. This makes it impossible to integrate them into the chip, requiring external MOSFETs for connection. However, external MOSFETs not only increase costs but also occupy PCB space, which is detrimental to PCB layout. Utility Model Content

[0003] This utility model provides a negative voltage output circuit and display device, aiming to solve the problems of increased cost and unfavorable PCB layout caused by the current appearance of MOSFETs.

[0004] In a first aspect, this utility model provides a negative pressure output circuit applied to a display device. The negative pressure output circuit includes an enable module and a negative pressure conversion module. The enable module is connected to the control module of the display device and is used to receive the enable signal from the control module. One end of the negative pressure conversion module is connected to the enable module and the power supply respectively, and the other end of the negative pressure conversion module is connected to the display screen of the display device, used to convert positive pressure input into negative pressure output.

[0005] Furthermore, the enabling module includes a first switching transistor and a second switching transistor; the controlled terminal of the first switching transistor is connected to the control module, the first pole of the first switching transistor is grounded, the second pole of the first switching transistor is connected to the power supply and the controlled terminal of the second switching transistor respectively, the first pole of the second switching transistor is connected to the power supply, and the second pole of the second switching transistor is connected to the negative voltage conversion module.

[0006] Furthermore, the enabling module also includes a first capacitor, one end of which is connected to the control module, and the other end of which is grounded.

[0007] Furthermore, the enabling module also includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; one end of the first resistor and one end of the second resistor are both connected to the power supply, the other end of the first resistor and one end of the third resistor are both connected to the second terminal of the first switching transistor, and the other end of the second resistor and the other end of the third resistor are both connected to the controlled terminal of the second switching transistor; one end of the fourth resistor is connected to the second terminal of the second switching transistor, the other end of the fourth resistor is connected to one end of the fifth resistor and the negative voltage conversion module, and the other end of the fifth resistor is connected to the negative voltage ground.

[0008] Furthermore, the negative pressure conversion module includes a negative pressure conversion chip, a first filter circuit, and a second filter circuit; the negative pressure conversion chip is connected to the power supply through the first filter circuit, the negative pressure conversion chip is connected to the display screen through the second filter circuit, and the negative pressure conversion chip is also connected to the second terminal of the second switching transistor.

[0009] Furthermore, the negative voltage conversion chip includes a power supply pin and a switch pin. The power supply pin is connected to the power supply through the first filter circuit, and the switch pin is grounded through the second filter circuit.

[0010] Furthermore, the first filter circuit includes a first inductor and a plurality of parallel capacitors; one end of the first inductor is connected to the power supply, the other end of the first inductor is connected to the negative voltage conversion chip, and the plurality of parallel capacitors are connected in parallel with the first inductor.

[0011] Furthermore, the second filter circuit includes a second inductor and a plurality of parallel capacitors; one end of the second inductor is connected to the switch pin, the other end of the second inductor is grounded, and the plurality of parallel capacitors are connected in parallel with the second inductor.

[0012] Furthermore, the negative voltage conversion chip also includes multiple grounding pins, which are connected to the display screen.

[0013] Secondly, this utility model also provides a display device, which includes a control module and the negative pressure output circuit described in any of the above claims.

[0014] The display device provided by this utility model includes a control module and a negative voltage output circuit. The negative voltage output circuit includes an enable module and a negative voltage conversion module. The enable module can control the start and stop of the negative voltage conversion module according to the enable signal of the control module. When the negative voltage conversion module is started, it can convert the positive voltage input into a negative voltage output to reduce the voltage stress on the MOSFET and avoid using an external MOSFET to solve the problem of high current. This not only reduces costs but also improves PCB layout. Attached Figure Description

[0015] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A block diagram of a negative voltage output circuit provided in an embodiment of the present invention;

[0017] Figure 2 A circuit diagram of an enable module provided in one embodiment of this utility model;

[0018] Figure 3 The circuit diagram of a negative pressure conversion module provided in one embodiment of this utility model. Detailed Implementation

[0019] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0020] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0022] See Figures 1 to 3 , Figure 1 A block diagram of a negative pressure output circuit 100 provided in an embodiment of the present invention; Figure 2 A circuit diagram of an enable module 10 provided in an embodiment of the present invention; Figure 3 This is a circuit diagram of a negative pressure conversion module 20 provided in one embodiment of the present invention. Figure 1 As shown, the negative pressure output circuit 100 provided by this utility model includes an enable module 10 and a negative pressure conversion module 20; the enable module 10 is connected to the control module 200 of the display device and is used to receive the enable signal of the control module 200; one end of the negative pressure conversion module 20 is connected to the enable module 10 and the power supply 400 respectively, and the other end of the negative pressure conversion module 20 is connected to the display screen 300 of the display device and is used to convert positive pressure input into negative pressure output.

[0023] Specifically, in display devices, such as OLED devices, the operating current increases accordingly with the increase in screen size. However, the on-resistance and heat dissipation capacity of the MOSFETs inside traditional integrated ICs are insufficient to withstand high currents, so they can only be connected externally to the chip. In traditional power supply schemes, the chip outputs both negative and positive voltage simultaneously, which leads to high requirements for the MOSFETs. Consequently, it is impossible to integrate the MOSFETs inside the chip, and they can only be connected externally, which increases costs and is not conducive to PCB layout.

[0024] The display device provided by this utility model may include a control module 200, a negative pressure output circuit 100, and a positive pressure output circuit. The positive pressure output circuit may be a buck converter circuit, which can step down the positive pressure input and convert it into a positive pressure output to power the display screen. Its specific circuit structure will not be described in detail here.

[0025] The negative voltage output circuit 100 includes an enable module 10 and a negative voltage output module. The control module 200 controls the start and stop of the negative voltage output module through the enable module 10. The negative voltage output circuit 100 can disconnect the chip reference ground from the power supply ground, making the chip reference ground the negative voltage output terminal. This can reduce the voltage difference between the source and drain of the internal MOSFET of the chip. For example, if the positive input is 12V, it can be converted by the negative voltage output circuit 100 to a negative output of 6.5V.

[0026] The enable module 10 is connected to the control module 200 and is used to control the start and stop of the negative pressure output module according to the enable signal of the control module 200. For example, a high level is a conduction signal and a low level is a stop signal. When the enable signal is high, the negative pressure output module starts and when the enable signal is low, the negative pressure output module stops.

[0027] When the negative voltage output module is started, it can convert the positive voltage input provided by the power supply 400 into a negative voltage output and output the negative voltage to the display screen 300. At the same time, the positive voltage output circuit outputs positive voltage to the display screen 300. By separating the positive voltage output and the negative voltage output, the requirements of each output circuit on the MOSFET can be reduced. Thus, there is no need to use an external MOSFET. Instead, the MOSFET can be integrated into the chip, which can not only reduce the circuit cost, but also improve the PCB layout.

[0028] The negative voltage output circuit 100 provided by this utility model is suitable for working currents of 3A and below. When the working current is not greater than 3A, the positive voltage input can be converted into a negative voltage output through the negative voltage output circuit 100. This allows the positive voltage output and negative voltage output to be separated, reducing the requirements of a single output circuit for MOSFETs. It can meet the requirements of large-size displays for integrated MOSFETs without increasing the circuit cost.

[0029] In a further embodiment, the enabling module 10 includes a first switching transistor Q1 and a second switching transistor Q2; the controlled terminal of the first switching transistor Q1 is connected to the control module 200, the first terminal of the first switching transistor Q1 is grounded, the second terminal of the first switching transistor Q1 is connected to both the power supply 400 and the controlled terminal of the second switching transistor Q2, the first terminal of the second switching transistor Q2 is connected to the power supply 400, and the second terminal of the second switching transistor Q2 is connected to the negative voltage conversion module 20. Furthermore, the enabling module 10 also includes a first capacitor C1, one end of which is connected to the control module 200, and the other end of which is grounded. Furthermore, the enabling module 10 also includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5; one end of the first resistor R1 and one end of the second resistor R2 are both connected to the power supply 400, the other end of the first resistor R1 and one end of the third resistor R3 are both connected to the second terminal of the first switching transistor Q1, the other end of the second resistor R2 and the other end of the third resistor R3 are both connected to the controlled terminal of the second switching transistor Q2; one end of the fourth resistor R4 is connected to the second terminal of the second switching transistor Q2, the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5 and the negative voltage conversion module 20, and the other end of the fifth resistor R5 is connected to the negative voltage ground.

[0030] In this configuration, both the first switching transistor Q1 and the second switching transistor Q2 can be transistors. The base of the first switching transistor Q1 is connected to the control module 200, its emitter is grounded, and its collector is connected to the first resistor R1 and the third resistor R3. The base of the second switching transistor Q2 is connected to the third resistor R3 and the second resistor R2, its emitter is connected to the power supply 400, and its collector is connected to the negative voltage conversion module 20 via the fourth resistor R4. Simultaneously, the collector of the second switching transistor Q2 is also connected to the negative voltage ground via the fourth resistor R4 and the fifth resistor R5. Figure 2 (ELVSS1 in the middle).

[0031] During operation, when the control module 200 outputs a high level, the first switch Q1 is turned on, pulling down the base of the second switch Q2, causing Q2 to turn off. The negative voltage conversion module 20 receives the high-level signal and begins operation. When the control module 200 outputs a low level, the first switch Q1 is turned off, pulling up the base of the second switch Q2, causing Q2 to turn on. The negative voltage conversion module 20 receives the low-level signal and stops operating.

[0032] In a further embodiment, the negative voltage conversion module 20 includes a negative voltage conversion chip U1, a first filter circuit 21, and a second filter circuit 22. The negative voltage conversion chip U1 is connected to the power supply 400 through the first filter circuit 21, and the negative voltage conversion chip U1 is connected to the display screen 300 through the second filter circuit 22. The negative voltage conversion chip U1 is also connected to the second terminal of the second switching transistor Q2. Further, the negative voltage conversion chip U1 includes a power supply pin and a switching pin. The power supply pin is connected to the power supply 400 through the first filter circuit 21, and the switching pin is grounded through the second filter circuit 22. Further, the first filter circuit 21 includes a first inductor and multiple parallel capacitors. One end of the first inductor is connected to the power supply 400, and the other end of the first inductor is connected to the negative voltage conversion chip U1. The multiple parallel capacitors are connected in parallel with the first inductor. Furthermore, the second filter circuit 22 includes a second inductor and multiple parallel capacitors; one end of the second inductor is connected to the switch pin, the other end of the second inductor is grounded, and the multiple parallel capacitors are connected in parallel with the second inductor. Furthermore, the negative voltage conversion chip U1 also includes multiple grounding pins, which are connected to the display screen 300.

[0033] Among them, such as Figure 3As shown, the negative voltage conversion module 20 may include a negative voltage conversion chip U1, a first filter circuit 21, and a second filter circuit 22. The first filter circuit 21 may include capacitors C1 to C7 and a first inductor. Capacitors C1 to C7 are connected in parallel with the first inductor, and all capacitors C1 to C7 are grounded. One end of the first inductor is connected to the power supply 400, and the other end is connected to the input pin of the negative voltage conversion chip U1, as shown below. Figure 3 VIN0, VIN1, and VIN2.

[0034] The second filter circuit 22 includes capacitors C13 to C17 and a second inductor, with capacitors C13 to C17 connected in parallel with the second inductor. One end of the second inductor is connected to the switch pin. Figure 2 The first inductor has two terminals (SW1 and SW0) connected to the first inductor, and the other end of the second inductor is grounded. The outputs of SW1 and SW0 are output to GND via the first inductor.

[0035] The negative voltage conversion chip U1 has AGN1, GND1, GND2, GND0 and EPAD as negative voltage outputs, which are used to output negative voltage to power the display screen 300.

[0036] A 12V positive power supply is input to the VIN0, VIN1, and VIN2 pins. The filter capacitor is connected to GND (i.e., the negative power supply or ground). The internal chip reference ground (AGN1, GND1, GND2, GND0, and EPAD) of the negative voltage conversion chip U1 is no longer connected to GND (the negative power supply or ground). Instead, it is disconnected from GND through conversion, thus forming a new output potential ELVSS1 to provide negative voltage power to the OLED display 300. When the high-side MOS input of the negative voltage conversion chip U1 is high, the MOS is turned on, the inductor is in a charging state, and the current flowing through the inductor increases linearly, eventually returning to the input terminal GND. When the low-side MOS input is high, the low-side MOS is turned on, and the high-side MOS is turned off. The inductor L discharges through the MOS, the inductor current decreases linearly, and the output negative voltage is discharged by the output filters C13 to C17.

[0037] This utility model also provides a display device, which includes a control module 200 and a negative pressure output circuit 100 as described in any of the above embodiments; the negative pressure output circuit 100 includes an enable module 10 and a negative pressure conversion module 20; the enable module 10 is connected to the control module 200 of the display device and is used to receive the enable signal of the control module 200; one end of the negative pressure conversion module 20 is connected to the enable module 10 and the power supply 400 respectively, and the other end of the negative pressure conversion module 20 is connected to the display screen 300 of the display device, and is used to convert positive pressure input into negative pressure output.

[0038] Specifically, in display devices, such as OLED devices, the operating current increases accordingly with the increase in screen size. However, the on-resistance and heat dissipation capacity of the MOSFETs inside traditional integrated ICs are insufficient to withstand high currents, so they can only be connected externally to the chip. In traditional power supply schemes, the chip outputs both negative and positive voltage simultaneously, which leads to high requirements for the MOSFETs. Consequently, it is impossible to integrate the MOSFETs inside the chip, and they can only be connected externally, which increases costs and is not conducive to PCB layout.

[0039] The display device provided by this utility model may include a control module 200, a negative pressure output circuit 100, and a positive pressure output circuit. The positive pressure output circuit may be a buck converter circuit, which can step down the positive pressure input and convert it into a positive pressure output to power the display screen. Its specific circuit structure will not be described in detail here.

[0040] The negative voltage output circuit 100 includes an enable module 10 and a negative voltage output module. The control module 200 controls the start and stop of the negative voltage output module through the enable module 10. The negative voltage output circuit 100 can disconnect the chip reference ground from the power supply ground, making the chip reference ground the negative voltage output terminal. This can reduce the voltage difference between the source and drain of the internal MOSFET of the chip. For example, if the positive input is 12V, it can be converted by the negative voltage output circuit 100 to a negative output of 6.5V.

[0041] The enable module 10 is connected to the control module 200 and is used to control the start and stop of the negative pressure output module according to the enable signal of the control module 200. For example, a high level is a conduction signal and a low level is a stop signal. When the enable signal is high, the negative pressure output module starts and when the enable signal is low, the negative pressure output module stops.

[0042] When the negative voltage output module is started, it can convert the positive voltage input provided by the power supply 400 into a negative voltage output and output the negative voltage to the display screen 300. At the same time, the positive voltage output circuit outputs positive voltage to the display screen 300. By separating the positive voltage output and the negative voltage output, the requirements of each output circuit on the MOSFET can be reduced. Thus, there is no need to use an external MOSFET. Instead, the MOSFET can be integrated into the chip, which can not only reduce the circuit cost, but also improve the PCB layout.

[0043] The negative voltage output circuit 100 provided by this utility model is suitable for working currents of 3A and below. When the working current is not greater than 3A, the positive voltage input can be converted into a negative voltage output through the negative voltage output circuit 100. This allows the positive voltage output and negative voltage output to be separated, reducing the requirements of a single output circuit for MOSFETs. It can meet the requirements of large-size displays for integrated MOSFETs without increasing the circuit cost.

[0044] The negative voltage output circuit of this invention allows the enable module to control the start and stop of the negative voltage conversion module according to the enable signal of the control module. When the negative voltage conversion module is started, it can convert the positive voltage input into a negative voltage output to reduce the voltage stress on the MOSFET, thereby eliminating the need for an external MOSFET. This not only reduces costs but also improves PCB layout.

[0045] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A negative voltage output circuit, characterized in that, The negative voltage output circuit, used in display devices, includes: An enabling module, which is connected to the control module of the display device, is used to receive an enabling signal from the control module; A negative pressure conversion module, one end of which is connected to the enable module and the power supply respectively, and the other end of which is connected to the display screen of the display device, is used to convert positive pressure input into negative pressure output.

2. The negative voltage output circuit as described in claim 1, characterized in that, The enabling module includes a first switching transistor and a second switching transistor; The controlled terminal of the first switching transistor is connected to the control module, the first pole of the first switching transistor is grounded, the second pole of the first switching transistor is connected to the power supply and the controlled terminal of the second switching transistor, the first pole of the second switching transistor is connected to the power supply, and the second pole of the second switching transistor is connected to the negative voltage conversion module.

3. The negative voltage output circuit as described in claim 2, characterized in that, The enabling module further includes a first capacitor, one end of which is connected to the control module, and the other end of which is grounded.

4. The negative voltage output circuit as described in claim 3, characterized in that, The enabling module further includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; One end of the first resistor and one end of the second resistor are both connected to the power supply, the other end of the first resistor and one end of the third resistor are both connected to the second terminal of the first switching transistor, and the other end of the second resistor and the other end of the third resistor are both connected to the controlled terminal of the second switching transistor. One end of the fourth resistor is connected to the second terminal of the second switching transistor, and the other end of the fourth resistor is connected to one end of the fifth resistor and the negative voltage conversion module, respectively. The other end of the fifth resistor is connected to the negative voltage ground.

5. The negative voltage output circuit as described in claim 2, characterized in that, The negative pressure conversion module includes a negative pressure conversion chip, a first filter circuit, and a second filter circuit; The negative voltage conversion chip is connected to the power supply through the first filter circuit, the negative voltage conversion chip is connected to the display screen through the second filter circuit, and the negative voltage conversion chip is also connected to the second terminal of the second switching transistor.

6. The negative voltage output circuit as described in claim 5, characterized in that, The negative voltage conversion chip includes a power supply pin and a switch pin. The power supply pin is connected to the power supply through the first filter circuit, and the switch pin is grounded through the second filter circuit.

7. The negative voltage output circuit as described in claim 5, characterized in that, The first filter circuit includes a first inductor and multiple parallel capacitors; One end of the first inductor is connected to the power supply, and the other end of the first inductor is connected to the negative voltage conversion chip. Multiple parallel capacitors are connected in parallel with the first inductor.

8. The negative voltage output circuit as described in claim 5, characterized in that, The second filter circuit includes a second inductor and multiple parallel capacitors; One end of the second inductor is connected to the switch pin, and the other end of the second inductor is grounded. Multiple parallel capacitors are connected in parallel with the second inductor.

9. The negative voltage output circuit as described in claim 5, characterized in that, The negative pressure conversion chip also includes multiple grounding pins, which are connected to the display screen.

10. A display device, characterized in that, The display device includes a control module and a negative pressure output circuit as described in any one of claims 1-9.

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