TWI282955B - Lamp drive circuit - Google Patents

Abstract

The lamp drive circuit at least includes three transformers and two lamps. The first transformer couples with a first end of the first lamp and the second transformer couples with a second end of the first lamp. The first transformer and the second transformer are used for driving the first lamp. The second transformer couples with a first end of the second lamp and the third transformer couples with a second end of the second lamp. The second transformer and the third transformer are used for driving the second lamp. Wherein the second transformer includes a first secondly coil and a second secondly coil. The first secondly coil couples with the second end of the first lamp. The second secondly coil couples with the first end of the second lamp. The number of coil turns of first secondly coil is equal to the number of the second secondly coil substantially.

Description

.1282955

达达编号·· TW2218PA IX. Description of the invention: ′ [Technical field to which the invention pertains] The present invention relates to a lamp driving circuit, and more particularly to a lamp driving circuit for use in a liquid crystal display. [Prior Art] As the size of a liquid crystal display continues to increase, for example, a large-sized liquid crystal television must have an increased brightness required for its moonlight module to maintain the image quality of the book. Therefore, in order to improve the brightness of the backlight module, in addition to the use of larger-sized lamps, it is necessary to increase the number of lamps used to achieve the desired brightness. However, in the traditional multi-lamp voltage supply circuit, the transformer pushes a plurality of lamps: When the lamp is used, the lamp is driven in two ways: (1) the lamps are connected in series, (2) the lamps are connected in parallel, and (2) the use is large. Transformers. However, the first method, that is, the series connection of the lamps, although the current balance problem can be overcome, the transformer withstand voltage problem is not easy to handle. The second method, that is, the parallel connection of the lamps, requires an additional balancing circuit, but it will increase the cost. The third approach, the use of multiple transformers, will also increase the cost and take up more space in the LCD display. Therefore, under the condition of driving a plurality of large-sized lamps, how can the driving circuit balance the current between the lamps and the transformer withstand voltage and insulation, which is the current large-size liquid crystal in the industry. Display || Two solutions to the problem. [Invention] The present invention aims to provide a lamp driving circuit capable of solving the problem that when a plurality of large-sized lamps are driven, the current between the lamps is not 5 1282955

Sanda number: TW2218PA balance problem, and can also take into account the voltage resistance of its own transformer and manufacturing costs. According to an object of the present invention, a lamp driving circuit is provided, which includes a first lamp tube, a second lamp tube, a first magnetic core, a first primary side winding group, a first secondary side coil, and a second magnetic core. a second primary side winding group, a second secondary side coil, a third secondary side coil, a third magnetic core, a third primary side winding group and a fourth secondary side coil. The first side winding set is wound on the first core and is used to receive the first alternating voltage. The first secondary side coil is wound around the first core. One end of the first tube is connected to the first secondary side coil. A second primary side winding set is wound around the second core and is adapted to receive a second alternating voltage. The second alternating voltage and the first alternating voltage are mutually inverted. The second secondary side coil is wound around the second core. The other end of the first tube is coupled to the second secondary side coil. The third secondary side coil is wound around the second core. One end of the second tube is connected to the third secondary side coil. The third primary winding group is wound around the two magnetic cores and is used to receive the third alternating voltage. The third alternating voltage is in phase with the first alternating current and the pressure system. The fourth secondary side coil is wound around the third core. Second = the other end of the tube is coupled to the third secondary side coil. And the second-time side winding group and the third one

Wherein, the first-order side winding group and the second-order full-side winding group each have a secondary side coil and the same number of windings.

In order to make the above-mentioned preferred embodiment of the present invention, the preferred embodiment, and the drawings are described in detail as follows: 1282955

[Claim Number] TW2218 (061218) CRJF [Embodiment] First Embodiment Referring to Fig. 1, there is shown a circuit diagram of a lamp driving circuit according to a first embodiment of the present invention. The lamp driving circuit 100 includes N transformers 102(1) to 102(N) and root lamps 104(1) to 104(M), N, ]V [which are positive integers and N-M=l. The N transformers 1〇2 are respectively used to generate driving voltages required to drive the root lamps 104(1) to 1〇4(Μ). The lamps 1040) 404 are used in a backlight module (not shown in Fig. 1), for example, an XJ-shaped cold cathode tube lamp. The backlight module is used in a liquid crystal display, such as a liquid crystal television. In order to provide the light source required for the display screen of the liquid crystal display panel, in the first figure, N=3, M=2 is taken as an example for drawing. According to the above, taking Ν=3, M=2 as an example. The three transformers 1〇2 are the first transformer 102(1), the second transformer 1〇2(2) and the third transformer 102(3), respectively. The first transformer ^20) includes the first core (7).丨), the first-side winding group 108(1) and the first secondary winding 11〇(1). The first primary side winding group 1〇8 (丨) and the first secondary side coil 110 (1) The system is both wound on the first core 106(1). The first polarity end of the first secondary side coil 11〇(1) (as indicated in Fig. 1, that is, the current outflow end) is coupled To one end of the first lamp 1〇4(1). The first primary side winding group 108(1) is configured to receive a first alternating voltage 八) to make the first secondary side coil 110 (1) Producing a voltage required to drive the first lamp. The second transformer 102(2) includes a second magnetic 106 (2), second primary side winding, and 108 (2), first secondary side coil 11 〇 (2) and third secondary side coil 11 〇 (3). This first one-person The side winding group 108 (2), the second secondary side coil 110 (2) and the third secondary side coil 110 (3) are both wound around the second core 1 6 (2). The first tube The other end of 1〇4(1) is coupled to the first polarity end of the second secondary side coil 11〇(2) (also shown on FIG. 1), and one end coupling of the second tube 104(2) Connected to the third secondary coil 7

1282955

Sanda number: TW2218 (061218) CRF 110 (3) first polarity end. The second primary side winding set 108(2) is for receiving a second 'AC voltage AC(2). The second AC voltage AC(2) and the first AC voltage system AC(1) are mutually inverted, so that the second secondary side coil 110(2) senses driving the first lamp 104(1). The required AC voltage and the third secondary side coil 11 〇 (3) sense the AC voltage required to drive the second lamp 104 (2). Further, the AC voltage induced by the second secondary side coil 11 (2) is in phase with the AC voltage induced by the third secondary side coil 110 (3). The third transformer 102 (3) includes a third core 106 (3), a third primary side winding group 108 (3) and a fourth secondary side coil 11 〇 (4). The third primary side winding group 1〇8(3) and the fourth secondary side coil 110(4) are both wound around the third core 1〇6(3). The other end of the second lamp 104 (2) is connected to the first polarity end of the third secondary side coil 110 (4). The third primary side winding group 1 8 (3) is for receiving a third alternating voltage AC (3). The third alternating voltage AC(3) is in phase with the first alternating current voltage AC(1) such that the third secondary side coil 110(4) generates the alternating current required to drive the second tube 1〇4(2). Voltage. The method for generating the first alternating current voltage AC(1), the second alternating current voltage AC(2), and the third alternating current voltage AC(3) may be generated by using a full bridge circuit or a half bridge circuit. In the embodiment, the type of the AC voltage Ac is not limited, as long as the transformers 1〇2(1)~1〇2(3) can be generated to drive the lamp officers 104(1) and 1〇. 4 (2) The required voltage can be. The second polarity ends of the secondary side coils 110(1) to 110(4) are, for example, all coupled to the ground, and the first polarity ends of the secondary side coils 110(1) to 110(4) are respectively A corresponding capacitor C1~C4 is coupled to the corresponding lamp 104(1)~1〇4(2). Each of the primary side winding groups 108(1) to 108(3) has substantially the same number of windings. The secondary side coils 11 (1) to 11 (4) also have substantially the same number of windings. Of course, the lamp impedance corresponding to each lamp 1〇4(1)~104(2) is slightly 8 1282955

Sanda number: TW2218PA When there is a difference, the number of windings of these secondary side coils 11〇(1), Il()(2), 11Q(3)′ and 110(4) will be slightly adjusted to achieve the current of the present invention. The purpose of balance. Further, the current balance of the present invention will be explained. Since the voltage required to drive the first lamp 104(1) is provided by the first transformer 102(1) and the second transformer 1〇2(2), the voltage required to drive the second lamp 104(2) It is provided by the second transformer 102 (2) and the third transformer 1 〇 2 (3). From the circuit structure of the second transformer 1〇2(2), the second secondary side coil 110(2) and the third secondary side coil 11〇(3) are wound around the same core 106 ( 2) Up, so the second secondary ring u〇(2) has the same magnetic circuit as the third secondary side coil 11〇(3), and flows through the second secondary side coil because the number of windings is the same 110(2) is almost the same as the current of the third secondary side coil ιι (3). This means that the current n flowing through the first lamp 1〇4(1) and the current 12 of the second lamp 104(2) (as indicated in Fig. 1) will be almost the same, that is, the currents η and 12 are balanced. . Finally, the brightness produced by the first tube 104(1) and the second tube 1〇4&) is made closer. Based on the above structure and spirit, it is possible to drive more of the lamps 1〇4 and balance the currents of the lamps 1〇4, as shown in Fig. 2, which is a schematic diagram of an example of the lamp driving circuit. The lamp driving circuit 1 includes five transformers 102(1) to 1G2(5) and four lamp officers 1G4(1)~(10)(4). Except for the first transformer 1〇2(1) and the carrying (5), the remaining transformers 102(7) and 1〇2(4) each have two secondary side coils 110 and the two secondary side coils 110 are wound on the corresponding magnetic cores 1〇6, respectively. Thus, the first lamp 1〇4(1) and the second lamp f1〇4(7) are brought to current by the second secondary side coil 11〇(7) and the third secondary side coil ιι〇(7) of the second transformer 102(2). Balanced, and the second tube 104 (7) and the third tube 1 〇 4 (7) are by the fourth secondary side line 11 〇 (4) and the fifth secondary side coil 110 (5) of the second transformation 5102 (3) The current balance is reached, and so on, the adjacent two lamps ι 4 are respectively balanced by the corresponding secondary side coil 11 。. So, regardless of the liquid crystal display panel 1282955

达达号·· TW2218PA • How many lamps 104 need to be used, when these lamps 104 are used in the backlight module, the above structure will make the backlight module provide the light source to the liquid crystal display panel more evenly, let The image quality displayed on the LCD monitor is better. Moreover, without using the structure of the above-mentioned lamp driving circuit 100, it is not necessary to additionally design a balancing circuit on the front and rear ends of the plurality of lamps 104, only by the transformer structure required to drive the lamps 1〇4, such as the above-mentioned transformer 102 ( 2) The two secondary side coils 11〇(2) and 110(3) can balance the current. Thus, the manufacturing cost of the lamp driving circuit 1 can be greatly reduced by the fact that such additional balancing circuits are eliminated. In addition, in the transformer 102, for example, the second-human-side coils 110(2) and 11〇(3) of the second transformer 102(2) respectively output AC voltages of the same phase, so the transformer 102(2) Security is even more increased. That is to say, the alternating voltage of different phases is not caused by the two secondary side coils 110 (2) and 11 〇 (3), respectively, so that the transformer 102 (2) has a problem of withstand voltage or insulation. SECOND EMBODIMENT Next, the lamp driving circuit 1 is exemplified by driving the u-shaped lamp in the first and second figures, and the lamp strip 4 of the general strip shape can be driven. Please refer to FIG. 3, which is a circuit diagram of a lamp driving circuit of a second embodiment of the present invention. The lamp driving circuit 100' also includes a plurality of transformers (02), (N) and a plurality of lamps 1〇4'(1)~1〇4(Μ), N and Μ are positive integers, and The structure is the same as that of the above-described lamp driving circuit 100, except that the 灯-shaped lamp tube 104 is changed into a strip-shaped lamp tube 1〇4. Therefore, the principle and function of the action are not described here. Among them, the third picture is drawn with Ν=7 and Μ=6 as examples. The lamp driving circuit and the transformer structure disclosed in the above embodiments of the present invention enable the adjacent two lamps to achieve current balance by the corresponding secondary side coils. So no matter how many lamps need to be used for the liquid crystal display panel, using the above structure will be 1282955

Sanda number: TW2218PA * The light source provided to the liquid crystal display panel by the backlight module is more uniform, so that the image quality displayed by the liquid crystal display device is better and the cost required for the lamp driving circuit is further reduced. In view of the above, the present invention has been disclosed in a preferred embodiment, and is not intended to limit the present invention. Any person skilled in the art can make various kinds without departing from the spirit and scope of the present invention. The scope of protection and refinement of the present invention is therefore defined by the scope of the appended claims.

11 1282955

Sanda number: TW2218PA ^ [Simple description of the drawings] • Fig. 1 is a circuit diagram of a lamp driving circuit of the first embodiment of the present invention. • Figure 2 is a schematic diagram of an example of a lamp drive circuit. Fig. 3 is a circuit diagram of a lamp driving circuit of a second embodiment of the present invention. \ [Main component symbol description] 100, 100': lamp driving circuit 102, 102': transformer 104, 104': lamp tube 106, 106' · magnetic core 108, 108': primary side winding group 110, 110': secondary side winding coil 12

Claims (1)

1282955 Sanda number: TW2218PA X. Patent application scope: ' 1. A lamp driving circuit, comprising: at least a first lamp and a second lamp; a factory-^ a first core; / a first- a secondary winding group that is wound around the first core and configured to receive a first alternating voltage; a first secondary coil that is wound around the first core, the first tube One end is coupled to the first secondary side coil; a second magnetic core; a second primary side winding set is wound on the second magnetic core and configured to receive a second alternating voltage, the second The alternating current voltage is opposite to the first alternating current voltage system; a second secondary side coil is wound on the second magnetic core, and the other end of the first light tube ' is coupled to the second secondary side a third secondary side coil is wound on the second magnetic core, one end of the second tube is coupled to the third secondary side coil; a third core; • a third time a side winding group is wound on the third magnetic core and configured to receive a third alternating voltage, the third alternating current voltage The first alternating current voltage is in phase; and a fourth secondary side coil is wound on the third magnetic core, and the other end of the second light tube is connected to the third secondary side coil; wherein The first-second side winding group, the second primary side winding group and the third primary side winding group each have substantially the same number of windings, the first secondary side line, the circle, the second The secondary side coil, the third secondary side coil, and the fourth secondary side coil each have substantially the same number of windings. 13 1282955 Sanda number: TW2218PA • ) • The lamp driving circuit described in claim 1 is characterized in that the fourth lamp lamp and the second lamp tube are discharge lamp tubes. 々3. The lamp driving circuit of claim 1, wherein: the fourth lamp lamp and the second lamp tube are cold cathode tubes. 4. The lamp driving circuit of claim 1, wherein the d lamp and the second tube are used in a backlight module, and the backlight module is used to provide a liquid crystal display to display images. The required light source. 5. The lamp driving circuit of claim 1, wherein the lamp driving circuit is further configured to drive a third lamp, the lamp driving circuit further comprising: a fifth primary side coil, Rotating on the third core, the third lamp tube is connected to the fifth secondary side coil; a fourth core; a fourth primary side coil is wound around the fourth core And receiving a fourth alternating voltage, the fourth alternating voltage is in phase with the second alternating voltage; and a sixth secondary coil is wound on the fourth core, the third tube The other end is coupled to the sixth secondary side coil; wherein the fourth primary side winding group and the third primary side winding group have substantially the same number of windings, the fifth secondary winding The sixth secondary side coil and the fourth secondary side coil have substantially the same number of windings. 14 1282955 The repair of the month of the month is the replacement page: Patent Application No. 094129910 Amendment 102(1)-Η 102(2) — 102(3)-Η 104(1) 104(2) 1st image 1282955 Sanda number: TW2218PA 7. Designation of representative figure: ^ (1) The representative figure of this case is: Figure 3 • (2) Simple description of the symbol of the representative figure: 100 ,: Lamp driving circuit 102, ··Transformer 104, ·· Lamp 106,: Magnetic core 108,: Primary winding group 110,: Secondary winding coil 8. If there is a chemical formula in this case, please reveal the best Chemical formula showing the characteristics of the invention: none