Current sharing control circuit and power panel

Abstract

The utility model discloses a current sharing control circuit and a power panel, the current sharing control circuit comprises a current sharing control unit, the current sharing control unit comprises a plurality of parallel current sharing branches, each current sharing branch comprises a current limiting unit and a control subunit, and the current limiting unit is used for being connected with a power supply module of the power panel so as to receive trunk current output by the power supply module; one end of the control subunit is connected with the current limiting unit, the other end of the control subunit is used for being connected with a load lamp bead, and the control subunit is used for restraining current change on a current sharing branch where the control subunit is located to achieve current sharing. According to the current-sharing control circuit disclosed by the utility model, the primary circuit current input by the power supply module of the power panel is shunted to the current-sharing branches, and the current of all the current-sharing branches is ensured to be equal through the current-sharing control of the current limiting unit and the control subunit in each current-sharing branch, that is, the current output to the load lamp bead by each current-sharing branch is ensured to be equal, so that the load lamp bead is ensured to be uniform. Therefore, the problems of non-uniform screen display, power panel damage and the like are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of television sets, and particularly to a current sharing control circuit and a power supply board. Background Art

[0002] With the development of technology and the upgrading of consumer demands, television technology has been continuously advancing. Large-size and high-brightness television sets are favored by the market due to their excellent visual experience. In the design of such televisions, there are some technical challenges, and one of them is the current sharing problem of the backlight system. The backlight system is a key part of a liquid crystal television to display images. It illuminates the liquid crystal panel by providing uniform light sources to generate images. In large-size and high-brightness televisions, in order to achieve better brightness and color performance, the backlight circuit usually adopts a design of multiple parallel backlights. However, there are problems that the current magnitudes of the backlight branches are not equal, resulting in unequal currents output to the load lamp beads, and thus causing uneven screen display and damage to the power supply board. Summary of the Utility Model

[0003] The utility model provides a current sharing control circuit and a power supply board, aiming at solving the problem that the currents output from the constant current board to the load lamp beads in existing television sets are not equal.

[0004] To solve the above technical problems, on the one hand, the utility model provides a current sharing control circuit, which is applied to the constant current board of a television power supply board. The current sharing control circuit includes a current sharing control unit, and the current sharing control unit includes multiple parallel current sharing branches. Each current sharing branch includes a current limiting unit and a control sub-unit. Among them,

[0005] The current limiting unit is used to be connected to the power supply module of the power supply board to receive the trunk current output by the power supply module;

[0006] One end of the control sub-unit is connected to the current limiting unit, and the other end of the control sub-unit is used to be connected to the load lamp beads. The control sub-unit is used to suppress the current change on its own current sharing branch to achieve current sharing.

[0007] Further, the current limiting unit includes a current limiting resistor. One end of the current limiting resistor is used to be connected to the power supply module, and the other end is connected to the control sub-unit.

[0008] Further, the control sub-unit includes a triode and a detection resistor. The base of the triode is connected to the other end of the current limiting resistor. The collector of the triode is used to be connected to the load lamp beads. The emitter of the triode is connected to one end of the detection resistor, and the other end of the detection resistor is connected to the collector of the triode.

[0009] Further, the triode is an NPN-type triode.

[0010] Further, the current sharing control circuit further includes a constant current detection unit. The constant current detection unit includes a first resistor. One end of the first resistor is connected to the other end of the detection resistor and is used to connect to the constant current board. The other end of the first resistor is grounded and connected to the current sharing control unit.

[0011] Further, the constant current detection unit further includes a diode. The positive electrode of the diode is connected to the other end of the detection resistor, and the negative electrode of the diode is connected to the other end of the first resistor.

[0012] Further, the current sharing control circuit further includes an overcurrent protection unit. The overcurrent protection unit includes a second resistor, an anti-mis-trigger unit, and an anti-backflow unit. Among them, one end of the anti-mis-trigger unit is connected to the other end of the first resistor, the other end of the anti-mis-trigger unit is connected to one end of the second resistor, the other end of the second resistor is connected to the anti-backflow unit, and the other end of the anti-backflow unit is connected to the current sharing control unit.

[0013] Further, the anti-mis-trigger unit includes a capacitor. One end of the capacitor is connected to the other end of the first resistor, the other end of the capacitor is connected to one end of the second resistor, and the node between the capacitor and the second resistor is used to connect to the constant current board.

[0014] Further, the anti-backflow unit includes a plurality of parallel-connected diodes. The negative electrodes of the diodes are connected to the other end of the second resistor, and the positive electrodes of the diodes are connected to the current sharing control unit.

[0015] On the other hand, the present utility model also provides a power supply board. The power supply board includes a constant current board and a power supply module. The constant current board is provided with the above-mentioned current sharing control circuit, and the power supply module and the constant current board are connected to the current sharing control circuit.

[0016] The present utility model discloses a current sharing control circuit and a power supply board. The current sharing control circuit includes a current sharing control unit, and the current sharing control unit includes multiple parallel current sharing branches. Each current sharing branch includes a current limiting unit and a control sub-unit. Among them, the current limiting unit is used to connect to the power supply module of the power supply board to receive the main circuit current output by the power supply module; one end of the control sub-unit is connected to the current limiting unit, and the other end of the control sub-unit is used to connect to a load lamp bead. The control sub-unit is used to suppress the current change on its own current sharing branch to achieve current sharing. The current sharing control circuit disclosed by the present utility model shunts the main circuit current input by the power supply module of the power supply board to the current sharing branches. Through the current sharing control of the current limiting unit and the control sub-unit in each current sharing branch, it is ensured that the currents of all current sharing branches are equal, that is, it is ensured that the currents output from each current sharing branch to the load lamp beads are equal, thereby avoiding problems such as uneven screen display and damage to the power supply board. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 is a block schematic diagram of the current sharing control circuit provided by an embodiment of the present utility model;

[0019] Figure 2 is a block schematic diagram of the current sharing branch provided by an embodiment of the present utility model;

[0020] Figure 3 is a circuit schematic diagram of the current sharing control circuit provided by an embodiment of the present utility model;

[0021] Figure 4 is a block schematic diagram of the power supply board provided by an embodiment of the present utility model;

[0022] Reference Numerals:

[0023] 100. Power supply board; 200. Power supply module; 300. Constant current board; 400. Current sharing control circuit; 410. Current sharing control unit; 420. Constant current detection unit; 430. Overcurrent protection unit; 411. Current sharing branch; 4111. Current limiting unit; 4112. Control sub-unit; PR412. First current limiting resistor; PR428. Second current limiting resistor PR428; PR434. Third current limiting resistor; PQ406. First triode; PQ407. Second triode; PQ408. Third triode; PR435. First detection resistor; PR447. Second detection resistor; PR448. Third detection resistor; PD407. First diode; PD413. Second diode; PD414. Third diode; PD415. Fourth diode; PR449. First resistor; PR450. Second resistor; PCX103. Capacitor; FB. First port; FB1. Second port. Detailed implementation manners

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0026] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0027] It should be further understood that the term " / and / " used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] Please refer to Figures 1 to 4 , Figure 1 is a block diagram of a current sharing control circuit provided by an embodiment of the present invention. The current sharing control circuit can be used for the constant current board of a TV power supply board. As Figure 1As shown, the current sharing control circuit 400 includes a current sharing control unit 410. The current sharing control unit 410 includes multiple parallel current sharing branches 411. Each current sharing branch 411 includes a current limiting unit 4111 and a control sub-unit 4112. Among them, the current limiting unit 4111 is used to connect to the power supply module of the power supply board to receive the main circuit current output by the power supply module; one end of the control sub-unit 4112 is connected to the current limiting unit 4111, and the other end of the control sub-unit 4112 is used to connect to the load lamp beads. The control sub-unit 4112 is used to suppress the current change on its own current sharing branch 411 to achieve current sharing. The current sharing control unit 410 ensures that the currents of all the current sharing branches 411 are equal through current sharing control, that is, it ensures that the currents output from each current sharing branch 411 to the load lamp beads are equal, thereby avoiding problems such as uneven screen display of the TV and damage to the power supply board. Please continue to refer to Figure 1 , in this embodiment, the current sharing control circuit 400 further includes a constant current detection unit 420. One end of the constant current detection unit 420 is connected to the control sub-unit 4112 in the current sharing control unit 410 and is used to connect to the constant current board, so that the constant current board controls the total current output by the current sharing control circuit 400 to the load lamp beads according to the resistance value detected by the constant current detection unit 420. Please continue to refer to Figure 1 , in this embodiment, the current sharing control circuit 400 further includes an overcurrent protection unit 430. The first end of the overcurrent protection unit 430 is connected to the other end of the constant current detection unit 420, the second end of the overcurrent protection unit 430 is connected to the current sharing control unit 410, and the third end of the overcurrent protection unit 430 is used to connect to the constant current board so that the constant current board detects the current of the overcurrent protection unit 430 and determines whether to trigger overcurrent protection according to the detected current.

[0029] Please refer to Figure 2 , Figure 2 is a schematic block diagram of a current sharing branch provided by an embodiment of the present invention. As Figure 2As shown, the current limiting unit 4111 includes a current limiting resistor, and the control sub-unit 4112 includes a triode and a detection resistor. Among them, one end of the current limiting resistor is used to connect to the power supply module, and the other end is connected to the base of the triode. The current limiting resistor is used to prevent the current in the base of the triode from being too large, which may cause damage to the triode. The collector of the triode is used to connect to the load lamp bead, the emitter of the triode is connected to one end of the detection resistor, and the other end of the detection resistor is connected to the collector of the triode. Specifically, the total current input by the power supply module of the power supply board to the current sharing control circuit 400, that is, the trunk current, is shunted through multiple current sharing branches 411 to obtain branch currents. The branch currents pass through the current limiting resistor and are input to the base of the triode, causing a voltage difference between the base and the emitter of the triode. The collector and the emitter of the triode are turned on, and the load lamp bead lights up. Ideally, the branch currents of each current sharing branch 411 are equal. If the branch current of a certain current sharing branch 411 increases, on this current sharing branch 411 with the increased branch current, the collector current of the triode will increase, the voltage of the detection resistor will increase, resulting in a decrease in the voltage difference between the base and the emitter of the triode and a decrease in the base current. Since the base current and the collector current of the triode are linearly related, the collector current will decrease, thereby suppressing the increase of the branch current, and further achieving current sharing, that is, ensuring that the currents of all current sharing branches 411 are always equal, which also ensures that the currents output from each current sharing branch 411 to the load lamp beads are equal, thus avoiding problems such as uneven screen display and damage to the power supply board. In this embodiment, the triode is an NPN type triode.

[0030] Figure 3 is the circuit schematic diagram of the current sharing control circuit provided by an embodiment of the present invention, as Figure 3As shown, in this embodiment, the current sharing control circuit 400 includes the current sharing control unit 410, the constant current detection unit 420, and the overcurrent protection unit 430. Among them, the current sharing control unit 410 includes three current sharing branches 411, namely the first current sharing branch, the second current sharing branch, and the third current sharing branch. The current limiting resistors include the first current limiting resistor PR412, the second current limiting resistor PR428, and the third current limiting resistor PR434. The triodes include the first triode PQ406, the second triode PQ407, and the third triode PQ408. The first triode PQ406, the second triode PQ407, and the third triode PQ408 are all NPN-type triodes. The detection resistors include the first detection resistor PR435, the second detection resistor PR447, and the third detection resistor PR448. Specifically, the first current limiting resistor PR412, the first triode PQ406, and the first detection resistor PR435 form the first current sharing branch; the second current limiting resistor PR428, the second triode PQ407, and the second detection resistor PR447 form the second current sharing branch; the third current limiting resistor PR434, the third triode PQ408, and the third detection resistor PR448 form the third current sharing branch. In this embodiment, the constant current detection unit 420 is composed of the first resistor PR449 and the first diode PD407, where the first diode PD407 is a fast recovery diode. In the overcurrent protection unit 430 of this embodiment, the anti-mis-triggering unit is the capacitor PCX103, the second resistor is the second resistor PR450, and the anti-backflow unit includes the second diode PD413, the third diode PD414, and the fourth diode PD415. In this embodiment, the load LED beads include VLED1, VLED2, and VLED3.

[0031] More specifically, as Figure 3As shown, for the first current sharing branch, one end of the first current limiting resistor PR412 is connected to the main path of the current sharing control unit 410, the other end of the first current limiting resistor PR412 is connected to the base of the first triode PQ406, the emitter of the first triode PQ406 is connected to one end of the first detection resistor PR435, and the collector of the first triode PQ406 is used to connect to VLED1. For the second current sharing branch, one end of the second current limiting resistor PR428 is connected to the main path of the current sharing control unit 410, the other end of the second current limiting resistor PR428 is connected to the base of the second triode PQ407, the emitter of the second triode PQ407 is connected to one end of the second detection resistor PR447, and the collector of the second triode PQ407 is used to connect to VLED2. For the third current sharing branch, one end of the third current limiting resistor PR434 is connected to the main path of the current sharing control unit 410, the other end of the third current limiting resistor PR434 is connected to the base of the third triode PQ408, the emitter of the third triode PQ408 is connected to one end of the third detection resistor PR448, and the collector of the third triode PQ408 is used to connect to VLED3. For the constant current detection unit 420, one end of the first resistor PR449 is connected to the other end of the third detection resistor PR448 and the first port FB, the other end of the first resistor PR449 is grounded, one end of the first diode PD407 is connected to the other end of the second detection resistor PR447 and the first port FB, and the other end of the first diode PD407 is connected to the other end of the first resistor PR449. Among them, the first diode PD407 is used to protect the first resistor PR449 when the load lamp beads are short-circuited. The first port FB is connected to the current sharing control chip of the constant current board, and is used for the current sharing control chip to detect the resistance value of the first resistor PR449 and control the total current output to VLED1, VLED2, and VLED3 according to the resistance value.For the overcurrent protection unit 430, one end of the capacitor PCX103 is connected to the other end of the first resistor PR449, the other end of the capacitor PCX103 is connected to one end of the second resistor PR450, the other end of the second resistor PR450 is connected to the cathodes of the second diode PD413, the third diode PD414, and the fourth diode PD415. The anode of the second diode PD413 is connected to the collector of the first triode PQ406, the anode of the third diode PD414 is connected to the collector of the second triode PQ407, and the anode of the fourth diode PD415 is connected to the collector of the third triode PQ408. Among them, the second resistor PR450 plays a role in current limiting to protect the circuit, and the capacitor PCX103 plays a role in storing and stabilizing the voltage, preventing the voltage of the second port FB1 from being unstable and causing the current sharing control chip to mis-trigger overcurrent protection. The second diode PD413, the third diode PD414, and the fourth diode PD415 prevent the current from flowing back. It should be noted that the +5V main circuit port is used to connect to the power supply module of the power supply board to receive the main circuit current output by the power supply module.

[0032] The following will combine Figure 3 to introduce the working process of current sharing control in detail:

[0033] After the main board of the TV set sends a power-on signal to the power supply board, the power supply module outputs a main circuit current with a voltage of +5V. The main circuit current is shunted to obtain three branch currents. The three branch currents are respectively fed to the first triode PQ406, the second triode PQ407, and the third triode PQ408 through the first current-limiting resistor PR412, the second current-limiting resistor PR428, and the third current-limiting resistor PR434, so that a voltage difference (the voltage difference is greater than 0.7V) is generated between the base and the emitter of the first triode PQ406, the second triode PQ407, and the third triode PQ408. The collector and the emitter of the first triode PQ406, the second triode PQ407, and the third triode PQ408 are turned on, and the first current-sharing branch, the second current-sharing branch, and the third current-sharing branch form a loop, so that VLED1, VLED2, and VLED3 are lit, and the TV set reaches the normal working state. In an ideal case, the magnitudes of the branch currents of the first current-sharing branch, the second current-sharing branch, and the third current-sharing branch are equal, and the first triode PQ406, the second triode PQ407, and the third triode PQ408 are all in the saturation state. If the current of a certain current-sharing branch changes, the currents of other current-sharing branches will also change. If the branch current of the first current-sharing branch increases, the collector current Ic of the first triode PQ406 will increase, resulting in an increase in the voltage of the first detection resistor PR435, and then resulting in a decrease in the voltage difference between the emitter and the base of the first triode PQ406, thereby reducing the base current Ib. And Ib = h * Ic. When Ib decreases, on the premise that the amplification factor h of the triode remains unchanged, Ic will also decrease accordingly, thereby suppressing the increase of the branch current and ensuring that the branch currents of the first current-sharing branch, the second current-sharing branch, and the third current-sharing branch are always equal, achieving the purpose of current sharing.

[0034] In one embodiment, such as this embodiment, a power supply board 100 is further provided. Please refer to Figure 4 , the power supply board 100 includes a constant current board 300 and a power supply module 200. The constant current board 300 is provided with the current sharing control circuit 400. In this embodiment, the power supply module 200 outputs current for the current sharing control circuit 400. The current sharing control chip of the constant current board 300 is connected to the current sharing control circuit 400 to control the total current flowing to VLED1, VLED2, and VLED3 and to control whether to trigger overcurrent protection.

[0035] In summary, the current sharing control circuit provided by the present utility model uses an NPN-type triode as the key component for current sharing control. Since the total current value input by the power supply module to the current sharing control circuit is fixed, when the branch current of one of the current sharing branches changes, the NPN-type triode in the current sharing branch where the branch current changes plays a feedback adjustment role, suppressing the change of the branch current, thereby achieving the balance of the branch current, significantly improving the current sharing performance of the backlight system of large-size high-brightness televisions, ensuring that the load lamp beads generate a uniform light source, and further ensuring the uniformity of the TV picture and the stability of the power supply board.

[0036] As described above, the above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. A current sharing control circuit, applied to a constant current board of a TV power board, characterized in that: The current sharing control circuit includes a current sharing control unit, the current sharing control unit includes a plurality of parallel current sharing branches, the current sharing branches include a current limiting unit and a control subunit, wherein: The current limiting unit is used to be connected to the power supply module of the power board to receive the main circuit current output by the power supply module; One end of the control subunit is connected to the current limiting unit, and the other end of the control subunit is used to connect to the load lamp bead. The control subunit is used to suppress the current change on the current sharing branch where it is located to achieve current sharing.

2. The current sharing control circuit according to claim 1, characterized in that: The current limiting unit includes a current limiting resistor, one end of which is used to be connected to the power supply module, and the other end of which is connected to the control subunit.

3. The current sharing control circuit according to claim 2, characterized in that: The control subunit includes a transistor and a detection resistor, the base of the transistor is connected to the other end of the current limiting resistor, the collector of the transistor is used to be connected to the load lamp bead, the emitter of the transistor is connected to one end of the detection resistor, and the other end of the detection resistor is connected to the collector of the transistor.

4. The current sharing control circuit according to claim 3, characterized in that: The transistor is an NPN transistor.

5. The current sharing control circuit according to claim 3, characterized in that: The current balancing control circuit also includes a constant current detection unit, which includes a first resistor, one end of which is connected to the other end of the detection resistor and is used to be connected to the constant current board, and the other end of the first resistor is grounded and connected to the current balancing control unit.

6. The current sharing control circuit according to claim 5, characterized in that: The constant current detection unit further includes a diode, an anode of the diode is connected to the other end of the detection resistor, and a cathode of the diode is connected to the other end of the first resistor.

7. The current sharing control circuit according to claim 5, characterized in that: The current balancing control circuit also includes an overcurrent protection unit, which includes a second resistor, an anti-false trigger unit and an anti-backflow unit, wherein one end of the anti-false trigger unit is connected to the other end of the first resistor, the other end of the anti-false trigger unit is connected to one end of the second resistor, the other end of the second resistor is connected to the anti-backflow unit, and the other end of the anti-backflow unit is connected to the current balancing control unit.

8. The current sharing control circuit according to claim 7, characterized in that: The anti-false triggering unit includes a capacitor, one end of the capacitor is connected to the other end of the first resistor, the other end of the capacitor is connected to one end of the second resistor, and a node between the capacitor and the second resistor is used to connect to the constant current plate.

9. The current sharing control circuit according to claim 7, characterized in that: The backflow prevention unit includes a plurality of diodes connected in parallel, wherein the cathode of the diode is connected to the other end of the second resistor, and the anode of the diode is connected to the current sharing control unit.

10. A power board, characterized in that: The power board includes a constant current board and a power supply module. The constant current board is provided with a current sharing control circuit as described in any one of claims 1 to 9. The power supply module and the constant current board are connected to the current sharing control circuit.

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