JP2009170667A - Capacitance-adjusting power-feed substrate, and discharge tube current equalization lighting device using the same, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive substrate capable of simply adjusting capacitances serially connected to respective discharge tubes, and restraining manufacturing cost; a discharge tube current equalization lighting device using the substrate; and a liquid crystal display. <P>SOLUTION: This substrate is provided with: a plurality of first conductors 301 and 302 formed on a surface S of an insulating substrate 16a by being separated from one another, and connected to the respective discharge tubes; capacitance-adjusting second conductors 311 formed between the first conductors 301 and 302 adjacent to each other on the surface S in a state without being connected to any of the first conductors; and a third conductor 32 formed oppositely to the first conductors 301 and 302 and the second conductors 311 on the back surface R of the insulating substrate 16a. As a result, capacitances can be formed in regions where the first conductors 301 and 302 overlap the third conductor 32. The values of the capacitances can be varied depending on whether the capacitance-adjusting second conductor 311 is jointed to either of the first conductors 301 and 302 adjacent to each other or not. Accordingly, the capacitances connected in series to the respective discharge tubes can be adjusted on a discharge tube basis, and high-frequency currents having values nearly equal to one another can be supplied to the respective discharge tubes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge tube equalizing lighting device and a liquid crystal display device for lighting a plurality of discharge tubes. Here, the “discharge tube” refers to a device that emits light by applying a high pressure to discharge into an ionized gas (plasma) in a sealed tube, such as a neon tube, a sodium lamp, a fluorescent tube, or a cold cathode tube. It corresponds to. “Uniform flow” means that high frequency currents having substantially the same magnitude are supplied to a plurality of discharge tubes.

For the backlights of various display devices such as liquid crystal display devices, cold cathode fluorescent tubes are used. Conventionally, a high-frequency lighting system using a high-frequency driving circuit has been adopted for lighting the cold cathode tube.
FIG. 13 is a circuit diagram illustrating an example of a high-frequency drive circuit. This high frequency drive circuit includes an inverter circuit 101 for supplying high frequency AC power of several tens kHz to several hundred kHz, a main transformer 102 for boosting the high frequency AC power, and an output line of the main transformer 102. A plurality of cold-cathode tubes 103 connected in parallel to each other, inserted at one end or both ends of each cold-cathode tube 103, and connected in series with each cold-cathode tube 103 in order to pass an equal current to each cold-cathode tube 103. And a current equalizing circuit 104 composed of a ballast capacitor.

In such a high-frequency driving circuit, the capacitor constituting the current-dividing circuit is formed integrally with the substrate 105 on the substrate 105 that supports one end of each cold cathode tube 103. That is, as shown in FIG. 14, each conductor 106 connected to each cold cathode tube 103 is provided separately on the surface of the substrate 105, and one conductor layer 107 is provided on the back surface of the substrate 105. Thus, the current sharing circuit 104 is configured by utilizing the area where the conductor layers 106 and 107 overlap the front and back surfaces, that is, the capacitance formed in the conductor.
JP 2005-322479 A

  However, in the current dividing circuit having the above structure, the capacitance cannot be increased or decreased once the conductor pattern is formed. Actually, each cold-cathode tube is fixedly disposed on a support plate that constitutes a part of the casing of the discharge tube equalizing lighting device via the substrate. Stray capacitance occurs between This stray capacitance has a different value for each cold-cathode tube depending on the position of each cold-cathode tube. Therefore, the brightness of light emission differs for each cold-cathode tube. In order to compensate for this difference in brightness, it is necessary to adjust the value of the capacitance connected in series with each cold cathode tube for each cold cathode tube. For this adjustment, it is troublesome to attach or remove the chip element.

Therefore, an object of the present invention is to provide a substrate that can easily adjust the capacitance connected in series to each discharge tube, and that can be manufactured at low cost and can be manufactured at a low cost.
Another object of the present invention is to provide a discharge tube equalizing lighting device and a liquid crystal display device using the substrate.

  The power supply substrate for capacity adjustment of the present invention is formed separately from each other, and the first conductors adjacent to each other on the surface on which the plurality of first conductors connected to each of the discharge tubes and the first conductor are formed. Between the conductors, a second conductor for capacity adjustment formed without being connected to any of the first conductors, and a third conductor formed opposite to the first conductor and the second conductor. It is characterized by.

  According to this configuration, the second conductor for capacity adjustment is joined to any one of the adjacent first conductors, thereby combining the first conductor and the second conductor, and the third conductor. A current sharing circuit for the discharge tube can be constructed by using a relatively large capacitance formed in a region where the discharge tube overlaps. Further, when the second conductor for capacity adjustment is not joined to any of the adjacent first conductors, using the capacitance created in the region where the first conductor and the third conductor overlap, A current-shaping circuit for the discharge tube will be constructed. The values of these capacitances can be changed depending on whether or not the capacitance adjusting second conductor is joined to any of the adjacent first conductors. Therefore, the capacitance connected in series with each discharge tube can be adjusted for each discharge tube.

The power supply substrate for capacity adjustment of the present invention has a structure in which the first conductor and the second conductor are formed on the surface of one insulating substrate, and the third conductor is formed on the back surface of the insulating substrate. Also good.
In the capacity adjustment power supply board according to the present invention, the first conductor and the second conductor are formed on one surface of one insulating substrate, and the second conductor is formed on one surface of another insulating substrate. You may have the structure which made the said one surface of two insulating substrates approach through the insulating film. With this structure, the capacitance of all capacitors can be uniformly adjusted by selecting the thickness and material of the insulating film.

The capacity adjustment power supply board of the present invention may have a substantially rectangular shape, and the plurality of first conductors may be formed independently of each other in a form of dividing the long side direction of the capacity adjustment power supply board. .
Further, if the third conductor has a structure in which the short side direction of the capacity adjustment power supply substrate is divided and formed, the separated conductor pieces of the third conductor are joined or joined together. By not doing so, the total capacitance can be adjusted uniformly. That is, depending on whether or not the second conductor for capacity adjustment is joined to any one of the adjacent first conductors, each capacitance can be individually adjusted, and the separated conductor pieces of the third conductor By joining or not joining, the total capacitance can be adjusted uniformly.

When the second conductor is divided into a plurality of conductor pieces between the adjacent first conductors, each capacitance can be individually finely adjusted.
The discharge tube current equalizing lighting device of the present invention includes a high-frequency drive circuit, a plurality of discharge tubes driven by the high-frequency drive circuit, and the above-described capacity adjustment power supply substrate, and the plurality of discharge tubes are configured to adjust the capacity. The third conductor is connected to a plurality of first conductors of the power supply board, and the third conductor is connected to a high frequency power supply end of the high frequency drive circuit. With this structure, each discharge tube and the high-frequency drive circuit can be connected with each capacitor formed on the capacity adjustment power supply board, and each capacitance formed on the capacity adjustment power supply board can be It can be adjusted easily. Therefore, high-frequency currents having substantially the same magnitude can be supplied to each discharge tube.

The discharge tube current equalizing apparatus further includes a support plate that supports the plurality of discharge tubes, and the plurality of discharge tubes are disposed between the capacity adjustment power supply substrate and the support plate. It may be adopted. Thereby, the stray capacitance generated between the capacitance adjusting power supply substrate and the support plate can be reduced.
The discharge tube may be a fluorescent lamp or a cold cathode tube.

  Moreover, the liquid crystal display device of the present invention uses the discharge tube equalizing lighting device as a backlight.

  As described above, according to the present invention, since the capacitance connected in series to each discharge tube can be adjusted for each discharge tube, the brightness of the discharge tube can be made uniform.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded view showing a liquid crystal display device 10 of the present invention. The liquid crystal display device 10 includes a liquid crystal display unit 11, a liquid crystal panel 12 that supports the liquid crystal display unit 11, and a current equalizing lighting device body 13.
The current equalizing lighting device main body 13 has a plurality of cold cathode tubes 15 fixedly arranged on a support plate 14 made of either or both of resin and metal. Is connected to a high-frequency driving circuit. When each of the plurality of cold cathode tubes 15 is shown, they may be expressed as cold cathode tubes 151. n is the number of cold cathode tubes (n> = 2).

  The liquid crystal display unit 11 has a horizontally long shape such as 4: 3, 16: 9, for example. The structure of the liquid crystal display unit 11 is a known structure, for example, a structure in which a transparent substrate on the surface side and a transparent substrate on the light source side face each other. The liquid crystal driving method may be a passive matrix type or an active matrix type. Taking the active matrix type as an example, a plurality of matrix-like transparent electrode groups are arranged on the inner surface of the transparent substrate on the front side, and one sheet is provided on the inner surface of the transparent substrate on the light source side so as to face the matrix-like transparent electrode group The semi-transparent electrode is installed. Further, an alignment film made of a resin rubbed in a certain direction is formed on each electrode. Liquid crystal is sealed between the alignment films. In the case of color liquid crystal, a color filter layer is provided on the transparent substrate on the front side.

The uniform current lighting device main body 13 has n cold cathode tubes 151... 15 n arranged in parallel with the long side direction of the liquid crystal display unit 11. One electrode (first conductor) of the capacity adjustment power supply board 16 is connected to the end of each cold cathode tube 151-15n, and the other electrode (third conductor) of the capacity adjustment power supply board 16 It is connected to a high-frequency power supply end of a high-frequency drive circuit described later.
The capacity adjustment power supply substrate 16 is fixed to the support plate 14 in a state parallel to the surface of the support plate 14. The one end portion of the cold cathode tube 15 can be supported by bending the one end conductor of the cold cathode tube 15 about 90 degrees and bonding and fixing the conductor to the capacity adjusting power supply substrate 16. The other end of the cold cathode tube 15 is also fixed by a similar structure.

  FIG. 2 is an overall circuit diagram of the uniform current lighting device including the high-frequency driving circuit 17 and a plurality of cold cathode tubes 15 connected thereto. This high frequency drive circuit 17 includes a rectifier circuit 22b connected to a commercial AC power source 22a, a switching circuit 23 for obtaining a high frequency AC power source of several tens of kHz based on the DC output of the rectifier circuit 22b, and a booster for the high frequency AC power source. A main transformer 24, a high-frequency power supply end 25 connected to the output line of the main transformer 24, and a plurality of cold cathode tubes 15 respectively connected in parallel to the high-frequency power supply end 25; The current equalizing circuit 18 is connected to each of the cold cathode fluorescent lamps 151 to 15n and flows the same current through the cold cathode fluorescent lamps 151 to 15n.

The current equalizing circuit 18 includes n capacitors C1 to Cn connected in series to the cold cathode tubes 151 to 15n. In FIG. 2, the capacitors C1 to Cn are connected to electrodes on one side of the cold cathode tubes 151 to 15n. However, as will be described later with reference to FIG. 11, the capacitors are connected to the cold cathode tubes 151 to 15n. A configuration in which the electrodes are connected to the electrodes on both sides may be adopted.
The operation of the high-frequency drive circuit 17 will be described. First, the DC power obtained by the rectifier circuit 22 b is converted into a high-frequency power by the switching circuit 23 and supplied to the main transformer 24. The AC frequency of the high-frequency power source is a frequency at which sufficient conversion efficiency is obtained for the main transformer 24, and is usually several tens of kHz to several hundreds of kHz. If the frequency is lower than this range, the main transformer 24 needs to be enlarged, and the entire device becomes large and heavy. When the frequency is higher than this range, the influence of the parallel capacitance generated in the main transformer 24 and the cold cathode tube 15 becomes large, resonance occurs, and the conversion efficiency decreases.

The main transformer 24 boosts the AC voltage at a predetermined boost ratio by having a predetermined number of turns and a turn ratio. As a result, an AC voltage (usually about 1000 V to 2000 V) necessary for lighting the cold cathode tubes 151 to 15n can be obtained.
The power source boosted by the main transformer 24 is supplied to the cold cathode tubes 151 to 15n through the capacitors C1 to Cn constituting the current dividing circuit 18. These capacitors C1 to Cn supply a uniform current to the cold cathode fluorescent lamps 151 to 15n by realizing a constant voltage drop.

Here, the structure of the capacitance adjusting power supply substrate for realizing each of the capacitors C1 to Cn constituting the current equalizing circuit 18 will be described in detail.
In the embodiment of the present invention, the capacity adjustment power supply substrate has a substantially rectangular shape. The power supply substrate for capacity adjustment is formed separately from each other, and is adjacent to the plurality of (n) first conductors connected to each of the cold cathode fluorescent lamps 151 to 15n and the surface on which the first conductor is formed. A second conductor for capacity adjustment formed between the first conductors and being not connected to any first conductor, and a third conductor formed opposite to the first conductor and the second conductor; Formed by.

An example of the structure of the capacitance adjusting power supply substrate is shown in FIGS. 3 is an external perspective view of the capacity adjustment power supply board 16, and FIG. 4 is a plan view (a), a front view (b), and a bottom view (c) of the capacity adjustment power supply board 16. FIG.
In this capacity adjustment power supply substrate 16, n first conductors 301 to 30 n (referred to collectively as first conductors 30) along the long side direction (indicated by x) on the surface S of the insulating substrate 16 a. ) Is formed by pattern printing or the like. Each of the first conductors 301 to 30n is formed independently of each other in the form of dividing the long side x of the substrate, and there is no direct electrical connection between the adjacent first conductors 30. On the surface S of the insulating substrate 16a, the second conductors 311 to 31 (n-1) for capacity adjustment (generic name) are connected between the adjacent first conductors 30 without any of the first conductors 30 being connected. Is sometimes formed by pattern printing. Each of the second conductors 31 is further divided into a plurality of conductor pieces P (five but not limited to five in the figure), and the plurality of conductor pieces P are electrically connected to each other. There is no direct connection.

One electrode of each cold cathode tube 151-15n is connected to each first conductor 301-30n by a joining member B such as solder.
On the back surface R of the capacity adjustment power supply board 16, as shown in FIG. 4C, a region where the third conductor 32 faces the first conductor 30 and the second conductor 31, that is, the capacity adjustment power supply board. 16 is formed on almost the entire back surface R of the surface.

In this way, the first conductors 301 to 30n face the third conductor 32 through the thickness of the insulating substrate 16a, so that each first conductor 301 to 30n has a capacitance between the first conductor 301 and the third conductor 32, respectively. Form. Each conductor piece P of each second conductor 31 also forms a capacitance with the third conductor 32.
The first conductor 30 and any conductor piece P of the second conductor 31 adjacent to the first conductor 30 can be joined to each other by a joining member such as solder or conductor paste. FIG. 3 shows an area A (referred to as a capacity adjustment joining area) A joined to each other by the joining member. When the conductors joined to each other in the capacitance adjusting junction region A are electrically integrated, the capacitances created for the respective conductors are combined.

  For example, in FIG. 3, since the first conductor 301 located at the end of the insulating substrate 16a and the three conductor pieces P constituting the second conductor 311 are combined, they are made of these conductors and combined. This capacitor becomes the capacitor C1 for driving the cold cathode tube 151. Further, since the first conductor 302 positioned next to the insulating substrate 16a and the two conductor pieces P constituting the second conductor 312 are combined, the combined capacitor made of these conductors is cooled. The capacitor C2 that drives the cathode tube 152 is obtained.

  In order to determine which conductor piece P of the second conductor 31 is to be joined to the first conductor 30 using a joining member such as solder or conductor paste, that is, the range of the capacity adjustment joining area A, Like this. One electrode of each cold cathode tube 151-15n is connected to each first conductor 301-30n, and the other electrode of each cold cathode tube 151-15n is grounded. All the cold cathode tubes 151... 15 n are turned on by the high-frequency driving circuit 17, and the current flowing through each of the cold cathode tubes 151 to 15 n is measured in a non-contact manner using a current transformer having an annular iron core. When the current value is smaller than the reference value, the conductor piece P is joined to the corresponding first conductor 30. This increases the capacitance between the corresponding first conductor 30 and third conductor 32. The number of conductor pieces P to be joined may be determined according to how much the measured current value is smaller than the reference value. Instead of measuring the current flowing through each cold cathode tube 151-15n using a current transformer, the brightness of each cold cathode tube 151-15n may be measured with a photometer. In this case, a large number of adjacent conductor pieces P are joined to the first conductor 30 corresponding to the relatively dark cold-cathode tube 15 to increase the capacitance of the capacitor connected to the cold-cathode tube 15. The adjacent conductor piece P is not joined to the first conductor 30 corresponding to the relatively bright cold cathode tube 15.

In this way, the capacitances C1 to Cn on the capacity adjustment power supply substrate 16 can be adjusted so that the high-frequency current flowing through the cold cathode tubes 151 to 15n is uniform.
In the description so far, conductors have been formed on the front surface S and the back surface R of the capacity adjustment power supply substrate, respectively. However, by using two insulating substrates and one insulating tape, the first conductor and the second conductor are formed on one surface of one insulating substrate, and the second conductor is formed on one surface of another insulating substrate 16c. It is also possible to form a capacitance adjusting power supply substrate by bonding the one surface of the two insulating substrates to each other via an insulating tape.

FIG. 5 is a plan view (a), a front view (b), and a bottom view (c) of the capacity adjustment power supply board 26 configured as described above.
In this capacity adjustment power supply substrate 26, as shown in FIG. 5A, n first conductors 301 to 30n are formed on one surface of one insulating substrate 16b along the long side direction, and the same. Between the adjacent first conductors 30 on the surface, the second conductors 311 to 31 (n−1) for capacity adjustment are formed in a state where no first conductor 30 is connected. Each second conductor 31 is further divided into a plurality (five in the figure) of conductor pieces P.

On one surface of the other insulating substrate 16c, as shown in FIG. 5C, a third conductor 32 is formed on almost the entire surface.
As shown in FIG. 5B, one surface of one insulating substrate 16b and one surface of another insulating substrate 16c are opposed to each other with an insulating tape 16d interposed therebetween. It is desirable that the insulating substrates 16b and 16c and the insulating tape 16d are not separated from each other by bonding or the like.

  In the capacity adjustment power supply board 26 of this structure, it is necessary to create a connection region in the first conductor 30 for connecting the first conductors 301 to 30n and the electrodes of the cold cathode tubes 151 to 15n. is there. Therefore, as shown in FIG. 5A, the width of one insulating substrate 16b is made wider than the width of the other insulating substrate 16c and the insulating tape 16d, and the first conductor 30 and the second conductor 31 are made accordingly. The width W1 is also made wider than the width W2 of the third conductor 32.

  FIG. 6 is a perspective view showing a state in which one surface of one insulating substrate 16b and one surface of another insulating substrate 16c are overlapped with each other via an insulating tape 16d. As shown in this figure, a region corresponding to the difference (W1−W2) between the width W1 of the first conductor 30 and the second conductor 31 and the width W2 of the third conductor 32 protrudes from the side of the insulating tape 16d. Therefore, in the protruding region, the electrodes of the cold cathode tubes 151 to 15n can be connected, and the first conductor 30 and any conductor piece P of the second conductor 31 adjacent to the first conductor 30 are connected to the solder, conductor paste. It can join by joining members, such as.

  As described above, the first conductors 301 to 30n face the third conductor 32 through the thickness of the insulating tape 16d, so that each first conductor 301 to 30n forms a capacitance with the third conductor 32, respectively. To do. Each conductor piece P of the second conductor 31 also forms a capacitance with the third conductor 32. If the first conductor 30 and any conductor piece P of the second conductor 31 adjacent to the first conductor 30 are joined by a joining member such as solder or conductor paste, the joined conductors can be electrically integrated. And the capacitance can be increased.

Next, an embodiment will be described in which the third conductor 32 is formed on the back surface R of the capacitance adjusting power supply substrate 16 so as to divide the short side direction of the substrate.
FIG. 7 is a plan view (a), a front view (b), and a bottom view (c) of the capacity adjustment power supply board 36 configured as described above.
In this capacity adjustment power supply board 36, the shapes of the first conductor 30 and the second conductor 31 formed on the surface S of the insulating substrate 16a are the same as those shown in FIG. On the back surface R, as shown in FIG. 7C, the third conductor 32 divides the short-side direction y of the substrate into a region facing the first conductor 30 and the second conductor 31. It is divided into a plurality of conductor pieces 321 to 323 in the form. Of the conductor pieces 321-323, the main conductor piece 321 connected to the high-frequency power supply end 25 has the largest area, and forms a large capacitance by facing the first conductor 30 and the second conductor 31. The conductor pieces 322 and 323 have a small area and can be joined to the main conductor piece 321 by a joining member such as solder or conductor paste. When the joined conductor pieces are electrically integrated with each other, the capacitance formed by the conductor pieces is also combined.

  In the structure of the capacitance adjusting power supply substrate 36, the capacitor C1 that drives the cold cathode tubes 151, the capacitor C2 that drives the cold cathode tubes 152, and the like are not individually adjusted, but the capacitors that drive the cold cathode tubes 151 to 15n. C1 to Cn can be increased or decreased all at once. That is, when the main conductor piece 321 is not connected to the conductor pieces 322 and 323, the capacitances of the capacitors C1 to Cn are relatively small, and when the main conductor piece 321 is joined to the conductor piece 322, the capacitances of the capacitors C1 to Cn. Will grow uniformly. If the main conductor piece 321 is joined to the conductor piece 322 and the conductor piece 323, the capacitances of the capacitors C1 to Cn are further increased.

Thus, by adopting the structure in which the third conductor 32 is divided and formed on the back surface R of the substrate, the overall brightness of the cold cathode fluorescent lamps 151 to 15n can be adjusted.
In the description so far, conductors have been formed on the front surface S and the back surface R of the capacity adjustment power supply substrate, respectively. However, using two insulating substrates and one insulating tape, the first conductor 30 and the second conductor 31 are formed on one surface of one insulating substrate 16b, and the third conductor 32 is replaced with another insulating substrate. It is also possible to form the capacity adjustment power supply board 46 by forming it on one surface of the substrate 16c, and bringing the one surface of the two insulating substrates 16b and 16c closer via an insulating tape 16d.

FIG. 8 is a plan view (a), a front view (b), and a bottom view (c) of the capacity adjustment power supply board 46 thus configured.
In this capacity adjustment power supply substrate 46, as shown in FIG. 8A, n first conductors 301 to 30n are formed on one surface of one insulating substrate 16b along the long side direction, and the same. Second conductors 311 to 31 (n-1) are formed between adjacent first conductors 30 on the surface. Each second conductor 31 is further divided into a plurality (five in the figure) of conductor pieces P.

As shown in FIG. 8C, a third conductor 32 is formed on one surface of the other insulating substrate 16c in a region facing the first conductor 30 and the second conductor 31, and The conductor is divided into a plurality of conductor pieces 321 to 323 so as to divide the short side direction.
In the capacity adjusting power supply board 46 of this structure, it is necessary to create a connection region in the first conductor 30 in order to connect the first conductors 301 to 30n and the electrodes of the cold cathode tubes 151 to 15n. As described with reference to FIGS. 5 and 6, it is necessary to make a connection region for joining the main conductor piece 321 and the conductor pieces 322 and 323 of the third conductor 32. Therefore, as shown in FIG. 8C, the length along the long side direction x of the insulating substrate 16 c is extended, and the length along the long side direction x of the third conductor 32 is changed to the first conductor 30 and the second conductor 32. It is made longer by U than the length of the two conductors 31. An area corresponding to the length difference U is a connection area for joining the main conductor piece 321 of the third conductor 32 to the conductor pieces 322 and 323.

9 and 10 are perspective views showing a capacitance adjusting power supply substrate 46 in which one surface of one insulating substrate 16b and one surface of another insulating substrate 16c are overlapped with an insulating tape 16d therebetween.
As shown in FIG. 9, in the insulating substrate 16b, a region corresponding to the difference (W1-W2) between the width W1 of the first conductor 30 and the second conductor 31 and the width W2 of the third conductor 32 is the insulating tape 16d. In this protruding region, the electrodes of the cold cathode tubes 151 to 15n are connected, or the first conductor 30 and any conductor piece P of the second conductor 31 adjacent thereto are soldered. It can be joined by a joining member such as a conductor paste.

As shown in FIG. 10, in the other insulating substrate 16 c, the third conductor 32 protrudes from the first conductor 30 and the second conductor 31 by a distance U along the long side direction of the substrate. In a region corresponding to this length difference U, the main conductor piece 321 of the third conductor 32 can be joined to the conductor pieces 322 and 323.
As described above, the first conductors 301 to 30n oppose the third conductor 32 through the thickness of the insulating tape 16d, whereby each first conductor 301 to 30n forms a capacitance with the third conductor 32, respectively. To do. Each conductor piece P of the second conductor 31 also forms a capacitance with the third conductor 32. If the first conductor 30 and any conductor piece P of the second conductor 31 adjacent to the first conductor 30 are joined by a joining member such as solder or conductor paste, the joined conductors can be electrically integrated. And the capacitance can be increased.

Further, by joining the main conductor piece 321 of the third conductor 32 to the conductor piece 322 or joining to the conductor pieces 322 and 323, the capacitors C1 to Cn for driving the cold cathode tubes 151 to 15n are collectively increased or decreased. be able to.
Although the embodiment of the present invention has been described so far, the present invention is not limited to the embodiment. For example, as shown in FIG. 11, current equalization circuits 181 and 182 may be connected to the electrodes on both sides of each cold cathode tube 151 to 15n. Capacitors constituting the current sharing circuit 181 are denoted as C11 to Cn1, and capacitors constituting the current equalization circuit 182 are denoted as C12 to Cn2. In this case, since the voltage between the high-frequency power supply terminals 25 and 25 can be divided by the two current-dividing circuits 181 and 182, the voltages applied to the capacitors C11 to Cn1 and C12 to Cn2 are the same as those shown in FIG. Compared to half. In this structure, the capacity adjustment power supply boards 16, 26, 36 and 46 of the present invention may be installed on both sides of the cold cathode tube 15. Since the withstand voltages of the insulating substrates 16a, 16b, 16c and the insulating tape 16d are lowered, the selection range of the insulator material can be expanded.

With the configuration of the present invention as described above, an equal current can be supplied to the plurality of cold-cathode tubes 151... 15n, and lighting can be performed with uniform brightness.
Although the embodiments of the present invention have been described so far, the present invention is of course not limited to the embodiments. For example, as shown in FIG. 12, there is also a structure in which a cold cathode tube 15 is installed on a support plate 14 made of either or both of resin and metal, and a capacity adjustment power supply board 16 is further arranged thereon. Is possible. According to this structure, the cold cathode tube 15 is disposed between the support plate 14 and the capacity adjustment power supply substrate 16. Accordingly, the distance between the support plate 14 and the capacity adjustment power supply board 16 can be made larger than that of the structure shown in FIG. 3, and the stray capacitance caused by the capacity adjustment power supply board 16 can be reduced. Further, the present invention is not limited to the cold cathode tubes used in the embodiments, and can be applied to general discharge tubes.

It is a disassembled perspective view which shows the liquid crystal display device 10 of this invention. 1 is an overall circuit diagram of a current equalizing lighting device of the present invention including a high-frequency drive circuit 17 and a plurality of cold cathode tubes 15 connected thereto. FIG. 4 is an external perspective view showing a state where a cold cathode tube is connected to a capacity adjustment power supply substrate 16. It is the top view (a), front view (b), and bottom view (c) of the power supply board 16 for capacity adjustment. A plan view (a), a front view (b), and a bottom view of a capacitance adjusting power supply substrate 26 in which one surface of one insulating substrate 16b and one surface of another insulating substrate 16c are overlapped with each other via an insulating tape 16d. (C). FIG. 3 is an external perspective view showing a state where a cold cathode tube is connected to a capacity adjustment power supply board 26. It is the top view (a), the front view (b), and the bottom view (c) of the capacity adjusting power supply substrate 36 in which the third conductor on the back surface R of the insulating substrate is formed by dividing the short side direction of the substrate. . A plan view (a), a front view (b), and a bottom view of a capacitance adjusting power supply substrate 46 in which one surface of one insulating substrate 16b and one surface of another insulating substrate 16c are overlapped with each other via an insulating tape 16d. (C). FIG. 5 is a perspective view showing the capacity adjustment power supply board 46. It is a perspective view which shows especially the edge part of the said electric power feeding board 46 for capacity | capacitance adjustment. It is a figure which shows the circuit example which connected the current equalization circuits 181 and 182 to the electrode of the both sides of each cold cathode tube 151-15n. It is a figure which shows the structure which installed the cold cathode tube 15 on the support plate 14, and has arrange | positioned the capacity | capacitance adjustment electric power feeding board 16 on it. It is a circuit diagram which shows an example of the discharge tube equality lighting apparatus using a capacitor. It is a perspective view which shows the example which formed the capacitor integrally with the said board | substrate on the board | substrate which supports the one end or both ends of each cold-cathode tube.

Explanation of symbols

10 Liquid crystal display device 10
DESCRIPTION OF SYMBOLS 11 Liquid crystal display part 12 Liquid crystal panel 13 Current equalizing lighting device main body 14 Support plate 15,151 ... 15n Cold cathode tube 16,26,36,46 Capacity adjustment electric power feeding board | substrate 16a, 16b, 16c Insulating board | substrate 16d Insulating tape 17 High frequency Drive circuit 18, 181, 182 Current equalization circuit 25 High frequency power supply terminals 30, 301 to 30n First conductor 31, 311 to 31 (n-1) Second conductor 32 Third conductor 321, 322, 323 Conductor piece A Capacity adjustment Joining area P Conductor piece

Claims (10)

A substrate for supporting one or both ends of a plurality of discharge tubes driven by a high-frequency driving circuit,
A plurality of first conductors formed separately from each other and connected to each of the discharge tubes;
On the surface where the first conductor is formed, between the adjacent first conductors, a second conductor for capacity adjustment formed in a state in which any first conductor is not connected,
And a third conductor formed to face the first conductor and the second conductor.   The capacity adjustment power supply board according to claim 1, wherein the first conductor and the second conductor are formed on a surface of a single insulating substrate, and the third conductor is formed on a back surface of the insulating substrate.   The first conductor and the second conductor are formed on one surface of one insulating substrate, the second conductor is formed on one surface of another insulating substrate, and the one surface of the two insulating substrates is bonded with an insulating film. The power supply board for capacity adjustment according to claim 1, wherein the power supply board is close to each other. The capacity adjustment power supply board has a substantially rectangular shape,
The power supply for capacity adjustment according to any one of claims 1 to 3, wherein the plurality of first conductors are independently formed in a form in which a long side direction of the capacity adjustment power supply board is divided. substrate.   5. The capacity adjustment power supply board according to claim 1, wherein the third conductor is separately formed so as to divide a short side direction of the capacity adjustment power supply board. 6.   6. The capacity adjustment power supply board according to claim 1, wherein the second conductor is divided into a plurality of conductor pieces between the adjacent first conductors. 7. A high frequency drive circuit, a plurality of discharge tubes driven by the high frequency drive circuit, and the capacity adjustment power supply substrate according to any one of claims 1 to 6,
The plurality of discharge tubes are respectively connected to a plurality of first conductors of the capacity adjustment power supply substrate, and the third conductor is connected to a high-frequency power supply end of the high-frequency drive circuit. Flow lighting device. And further comprising a support plate for supporting the plurality of discharge tubes,
The discharge tube equalizing lighting device according to claim 7, wherein the plurality of discharge tubes are arranged between the capacity adjustment power supply substrate and the support plate.   The discharge tube equalizing lighting device according to claim 7 or 8, wherein the discharge tube is a fluorescent lamp or a cold cathode tube.   A liquid crystal display device using the discharge tube uniform current lighting device according to claim 9 as a backlight.

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