JP2008091128A - Light source driving circuit board, sound insulating member, backlight device, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device capable of suppressing an echoing phenomenon of an inverter transformer at the time of light-control drive without affecting consumption power of the backlight and brightness control of the light source. <P>SOLUTION: The backlight device is provided with a plurality of light sources, an inverter transformer 29 to supply AC voltage to the plurality of light sources, an inverter circuit board 4 mounting the inverter transformer 29, and a soundproof cover 3 to suppress generated sound from the inverter transformer 29 mounted on the inverter circuit board 4. The soundproof cover 3 has a plurality of pawls 31 at the surrounding of the opening and the inverter circuit board 4 has a plurality of holes 41 corresponding to the plurality of pawls 31, and the plurality of pawls 31 are engaged with the plurality of holes 41 with the inverter transformer 29 housed in the soundproof cover 3. The number of the plurality of holes 41 installed in a non-high-voltage region is fewer than that installed in high-voltage region of the inverter circuit board 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light source drive circuit board, a soundproof member, a backlight device, and a liquid crystal display device. The present invention relates to a light device and a liquid crystal display device.

  In recent years, especially with the increase in screen size of liquid crystal display devices, the length of the fluorescent tube is either one of the vertical and horizontal lengths of the liquid crystal panel from the viewpoint of the uniformity of screen brightness and the number of parts (especially considering the uniformity of brightness). In many cases, it is designed according to the length of the direction. However, one of the problems that may occur with the lengthening of the fluorescent tube is the manifestation of the squealing phenomenon of the inverter transformer in the backlight device having a dimming control function using a PWM signal.

  This dimming control function transmits a rectangular wave (PWM signal) having a specific frequency (usually several tens to several hundreds of Hz) to the inverter circuit, thereby causing the fluorescent tube to be lit or not lit. It is provided for adjusting the brightness perceived by the human eye by controlling the ratio of the wave on and off periods within a period of about 60 Hz.

  The voltage generated from the inverter transformer requires high-voltage AC power to discharge the inside of the fluorescent tube, and a higher discharge voltage is required as the fluorescent tube becomes longer. As a result, the internal cores repeatedly collide more strongly with each other at the specific frequency described above, and as a result, the sound is generated with more emphasis from the transformer at the pitch according to the frequency.

In order to deal with such problems, there are mainly two examples of conventional noise reduction measures: a discharge voltage control method and a PWM dimming signal control method.
As an example of the discharge voltage control method, Patent Literature 1 describes a discharge lamp lighting device that supplies current that does not lead to lighting of a fluorescent tube to a winding transformer and a choke coil of the inverter circuit during the fluorescent tube extinguishing period. Yes. In addition, as an example of the PWM dimming signal control method, Patent Document 2 describes an inverter circuit that includes a step-up transformer and controls the rising characteristic and falling characteristic of a starting current that operates a switching element.
JP 2001-196196 A Japanese Patent Laid-Open No. 2004-173459

However, the conventional noise suppression measures according to Patent Documents 1 and 2 have the following problems.
In the discharge voltage control method, a voltage is always applied to the fluorescent tube even during the extinguishing period of the fluorescent tube, and more power is required even if the fluorescent tube is lit at the same brightness (≈Duty ratio). On the other hand, in the case of the dimming signal control method, when the ratio of the rising period to the signal period is increased by modulating the PWM signal waveform, it becomes difficult to control the brightness with a fine duty ratio (about 10% or less).

The present invention has been made in view of the above circumstances, and can suppress the squealing phenomenon of the inverter transformer during dimming drive without affecting the power consumption of the backlight or the brightness control of the light source. To provide a light source driving circuit board, a soundproof member, a backlight device, and a liquid crystal display device,
It is another object of the present invention to suppress the sound generation phenomenon during dimming driving so as not to limit the current flowing in the light source driving circuit board (particularly the primary side printed wiring pattern).

  In order to solve the above problems, a first technical means of the present invention is a light source driving circuit board including a transformer for supplying an alternating voltage to a light source, and a soundproof member for suppressing sound generated from the transformer It is characterized by having a fixing means for fixing.

  According to a second technical means, in the first technical means, the soundproof member includes a transformer accommodating portion that accommodates the transformer, and a plurality of locking portions around the opening of the transformer accommodating portion. A plurality of locked portions corresponding to the plurality of locking portions, and the plurality of locking portions are engaged with the plurality of locked portions in a state where the transformer is accommodated in the transformer accommodating portion. It is characterized by being stopped.

  According to a third technical means, in the second technical means, at least one of the plurality of locked portions is provided on a high-pressure region of the light source driving circuit board.

  A fourth technical means includes a printed wiring unit for mounting a plurality of the transformers and connecting primary windings of each of the plurality of transformers in the second technical means, At least one of the locked portions is provided on the high voltage region side from the printed wiring portion.

  According to a fifth technical means, in the second technical means, the number of the locked portions is equal to the number provided on the non-high voltage region than the number provided on the high voltage region of the light source driving circuit board. It is characterized by a small amount.

A sixth technical means includes a printed wiring unit for mounting a plurality of the transformers in the second technical means, and connecting primary windings formed by each of the plurality of transformers,
The plurality of locked portions are characterized in that the number provided in a region other than the high voltage region is smaller than the number provided on the high voltage region side than the printed wiring portion.

  A seventh technical means is any one of the third to sixth technical means, wherein the high-voltage region is a silk-printed region on at least one surface of the light source driving circuit board. It is.

  According to an eighth technical means, in the fourth or sixth technical means, the printed wiring portion is provided on the back surface of the mounting surface of the transformer.

  A ninth technical means is a soundproof member for suppressing sound generated from the transformer mounted on the light source drive circuit board, wherein the transformer is accommodated in the transformer accommodating part, and the transformer is accommodated in the transformer accommodating part. And a fixing means for fixing the light source driving circuit board to the light source driving circuit board.

  A tenth technical means is the ninth technical means, wherein the fixing means is composed of a plurality of engaging portions provided around the opening of the transformer accommodating portion, and the plurality of engaging portions are the light source driving circuit. It is characterized by being provided at a position corresponding to the high-pressure region side of the substrate.

  In an eleventh technical means according to the tenth technical means, at least one of the plurality of locking portions is provided at a position corresponding to a locked portion provided on a high voltage region side of the light source driving circuit board. It is characterized by that.

  According to a twelfth technical means, in the tenth technical means, at least one of the plurality of locking portions is a printed wiring portion for connecting between primary windings of the transformer formed by the light source driving circuit board. It is characterized in that it is provided at a position corresponding to the locked portion provided on the higher pressure region side.

  According to a thirteenth technical means, in the tenth technical means, the number of the locking portions locked in the non-high voltage region is greater than the number locked in the high voltage region of the light source drive circuit board. It is characterized by few.

  A fourteenth technical means is the tenth technical means, wherein the plurality of locking portions are on a higher voltage region side than a printed wiring portion for connecting the primary windings of the transformer formed by the light source driving circuit board. This is characterized in that the number locked in the area other than the high pressure area is smaller than the number locked in the area.

  A fifteenth technical means according to any one of the ninth to fourteenth technical means is characterized in that the transformer accommodating portion has a substantially rectangular parallelepiped space formed therein.

  The sixteenth technical means comprises any one of the first to eighth technical means and any one of the ninth to fifteenth technical means.

  The seventeenth technical means includes a plurality of light sources, a transformer for supplying an alternating voltage to the plurality of light sources, a light source driving circuit board on which the transformer is mounted, and sound generated from the transformer mounted on the light source driving circuit board. A sound-insulating member that suppresses the transformer, and the sound-insulating member includes a transformer housing part that houses the transformer, and a plurality of locking parts around the opening of the transformer housing part. A plurality of locked portions corresponding to the locking portions, and the plurality of locking portions are locked to the plurality of locked portions in a state where the transformer is accommodated in the transformer accommodating portion. It is characterized by.

  According to an eighteenth technical means, in the seventeenth technical means, the light source is controlled to be turned on or off by a substantially rectangular dimming signal.

  According to a nineteenth technical means, in the seventeenth technical means, at least one of the plurality of locked portions is provided on a high-voltage region of the light source driving circuit board.

  According to a twentieth technical means, in the seventeenth technical means, the light source driving circuit board is mounted with a plurality of the transformers, and a printed wiring for connecting between the primary windings formed by the plurality of transformers. And at least one of the plurality of locked portions is provided on the high-pressure region side with respect to the printed wiring portion.

  In a twenty-first technical means, in the seventeenth technical means, the number of the locked portions is greater than the number provided on the high-voltage region of the light source drive circuit board. It is characterized by a small amount.

  Twenty-second technical means is the printed circuit board according to the seventeenth technical means, wherein the light source driving circuit board mounts a plurality of the transformers and connects between the primary windings formed by the plurality of transformers. And the number of the plurality of locked portions provided in a region other than the high-voltage region is smaller than the number provided on the high-voltage region side than the printed wiring portion. is there.

  A twenty-third technical means is any one of the nineteenth to twenty-second technical means, wherein the high-voltage region is a silk-printed region on at least one surface of the light source driving circuit board. It is.

  According to a twenty-fourth technical means, in the twentieth or twenty-second technical means, the printed wiring portion is provided on a back surface of the mounting surface of the transformer.

  A twenty-fifth technical means comprises the backlight device according to any one of the sixteenth to twenty-fourth technical means and a liquid crystal panel illuminated by the backlight device.

According to the present invention, the sounding phenomenon of the inverter transformer during the dimming drive can be surely suppressed without affecting the power consumption of the backlight and the brightness control of the light source.
In addition, since the noise generation phenomenon during dimming drive can be suppressed without hindering the current capacity required for the primary side printed wiring pattern of the inverter circuit board, the noise of the inverter transformer can be reduced while reducing the risk of pattern damage. Can be suppressed. Further, the noise of the inverter transformer can be suppressed without imposing restrictions on the mounting area of each electronic component as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

  FIG. 1 is a cross-sectional view showing a configuration example of a liquid crystal display device using a backlight device according to the present invention. The liquid crystal display device includes a liquid crystal panel 1 and a backlight device 2 as main components. The liquid crystal panel 1 feeds the video signal subjected to the video signal processing as a predetermined gradation voltage for each pixel in accordance with the clock signal of the liquid crystal panel 1, and sequentially scans the screen to display the video corresponding to the video signal. indicate.

  The backlight device 2 irradiates light from the back side of the liquid crystal panel 1. As the light source of the backlight device 2, for example, a cold cathode fluorescent lamp (CCFL) is used.

  The backlight device 2 includes a plurality of fluorescent lamps 21 for supplying light to the liquid crystal panel 1, and a reflection sheet or reflector (hereinafter referred to as “reflecting sheet”) for effectively irradiating the liquid crystal panel 1 with the light emitted from each fluorescent lamp 21. And 22 (represented by a reflective sheet) and a housing (chassis) 23 for storing them.

  On the rear side of the housing 23, an inverter circuit board 4 corresponding to the light source driving circuit board of the present invention on which the inverter circuit is mounted is disposed. The inverter circuit board 4 is provided with an inverter transformer 29 that is a booster circuit that supplies power to each fluorescent lamp 21 and the soundproofing of the present invention that is attached to the board in order to suppress a roaring sound during dimming of the inverter transformer 29. A soundproof cover 3 corresponding to the member is provided. As the inverter transformer 29, for example, there is a winding type that transforms based on the winding ratio of the coils by the electromagnetic induction effect of two coils. As a material for the soundproof cover 3, a plastic resin (for example, a polycarbonate resin having a relatively high heat resistance) or the like is used.

  As the inverter circuit, for example, a separately excited inverter can be applied. In general, a separately excited inverter is provided with an oscillation circuit on the primary side and converts it into an alternating current having the same frequency as the drive frequency of the oscillation circuit. This separately excited inverter is used to drive the winding-type inverter transformer 29 as described above. By using it, it is possible to realize a small-sized and highly efficient inverter that exceeds the piezoelectric type inverter while being a winding type. The details of the configuration of the inverter circuit board 4 and the soundproof cover 3 according to the present invention will be described later.

  The liquid crystal panel 1 is composed of two glass substrates with polarizing plates having a crossed Nicols relationship with a liquid crystal layer interposed therebetween, and is fixedly held by two frames. The frame has a structure bent in a substantially L-shaped cross section so as to cover the entire backlight device 2.

The fluorescent lamp 21 constituting the backlight device 2 has a straight tube shape, and is arranged so that straight portions thereof are parallel to each other. As a light source of the backlight, a straight tube fluorescent lamp 21 is used, and electrodes on one side of two fluorescent lamps are connected to each other so that the same drive as that of the U-shaped tube is performed. In the present specification, a set in which the two fluorescent lamps are connected is referred to as a pseudo U-shaped tube. A configuration example of the pseudo U-shaped tube and a specific example of the driving method will be described later.
Further, not only the pseudo U-shaped tube as described above but also a normal U-shaped tube can be applied to the configuration of the backlight of the present invention.

  The backlight device 2 is further provided with various optical members according to the optical performance required for the liquid crystal display device. For example, a diffusion plate 24 that diffuses light from the fluorescent lamp 21, a diffusion sheet 25 that controls light distribution characteristics, a prism sheet 26 that condenses light in a specific direction, or selectively transmits polarization of light in a specific direction. A reflective polarizing plate 27 that reflects and improves the degree of polarization is appropriately disposed.

Moreover, the shape of the reflection sheet 22 may be, for example, a planar shape as shown in FIG.
A high-voltage AC voltage is supplied to the electrodes of the fluorescent lamp 21 from the inverter transformer 29 of the inverter circuit board 4 disposed substantially parallel to the back surface of the backlight device 2. Mercury in the fluorescent lamp 21 is excited by the high-voltage AC voltage, and light in the vicinity of ultraviolet rays is emitted by the energy level. The ultraviolet light emits red, blue, and green phosphors provided on the tube wall of the fluorescent lamp 21, and these emission colors are mixed to form white light.

  The white light thus emitted is acted on by the various optical members described above to illuminate the liquid crystal panel 1 from the back side of the liquid crystal panel 1. In each pixel of the liquid crystal panel 1, the light transmittance of each pixel is controlled according to a predetermined gradation voltage, and an image is displayed on the screen.

  FIG. 2 is an external view for explaining a configuration example of the soundproof cover 3 used in the backlight device 2 according to the present invention. 2A is a bottom view of the soundproof cover 3, FIG. 2B is a side view of the soundproof cover 3, and FIG. 2C is a front view of the soundproof cover 3. The soundproof cover 3 which is a soundproof member constituting the present invention is formed in a shape including the main body of the inverter transformer 29 mounted on the substrate by being attached to the inverter circuit substrate 4.

  As a specific example, it has a box-shaped transformer accommodating portion 32 partially including an opening for containing the inverter transformer 29, and is attached to the inverter circuit board 4 around the opening of the transformer accommodating portion 32. Claw 31a to 31d corresponding to the fixing means of the present invention. As for the number of claws provided in this soundproof cover, it is better to construct a plurality of claws so that the soundproof cover itself does not vibrate under the influence of sound and vibration from the transformer, and is securely fixed to the inverter circuit board. preferable.

  These claws 31a to 31d are attached so as to pass through holes (locked portions) 41a to 41d (described later) provided around the inverter transformer 29 mounted on the inverter circuit board, respectively. As a result, a state in which the claw is engaged with the back surface of the substrate is formed.

  In addition, the positions where these claws are attached are provided in the secondary (high voltage) circuit side region so as not to reduce the line width of the primary (low voltage) circuit side wiring pattern on the inverter circuit board as much as possible. It is preferable to design so that it is possible.

Referring to the specific example of FIG. 2, among the plurality of claws, the claw 31 a is provided on the high voltage side on the inverter circuit board 4, and the claw 31 c located at the opposite position is provided on the low voltage side. The remaining claws 31b and 31d are attached so as to be provided at a position on the high-pressure side from the middle point P of the long side of the opening having the substantially rectangular shape (that is, a position relatively closer to the claw 31a than the claw 31c). You can see that
Accordingly, the claws 31a, 31b, and 31d can be said to be located on the high pressure side with respect to the position of the housed transformer, and the remaining claws 31c can be said to be located on the low pressure side.

  In addition, the method for identifying the attachment position of the claw without departing from the technical idea of the present invention can be rephrased from another viewpoint. For example, specifying from the positional relationship with a part of the core member of the inverter transformer does not depart from the technical idea of the present invention, and the shape of the inverter transformer will be described below and specific matters based on the description will be described.

  Inverter transformers for backlight fluorescent tubes usually consist of one or two E-shaped cores, with the primary and secondary windings on the upper and lower protrusions of the letter “E”, and the remaining middle The protrusion of this is intended to improve the power conversion efficiency of the transformer by improving the coupling coefficient of this transformer by being close to other adjacent cores (E core or I core), so this middle protrusion is just It is located between the primary side winding and the secondary side winding. Therefore, the claws provided in the soundproof cover are positioned so as to be biased to the secondary winding side with respect to the protrusions located between the primary winding and the secondary winding among the core members constituting the accommodated inverter transformer. In other words, it can be said.

  While the soundproof cover according to the present invention has been described above, refer to the following for the description of the inverter circuit board to which the soundproof cover is attached.

  3 and 4 are external views for explaining a configuration example of the inverter circuit board 4 used in the backlight device 2 of the present invention. 3 shows the pattern wiring and silk print pattern on the surface of the substrate (surface on which the inverter transformer main body is arranged), and FIG. 4 shows the pattern wiring and silk on the back surface (surface facing the bottom surface of the chassis (backlight chassis)). A print pattern or the like is shown. Note that FIG. 4 showing the back surface of the substrate shows FIG. 3 showing the front surface in a state where only the left and right are reversed. As shown in any of the figures, the inverter circuit boards 4 are configured as a pair with the middle horizontal line as a boundary, and each board is attached in the vicinity of both ends of a plurality of fluorescent tubes arranged in parallel.

  Here, the above-described soundproof cover 3 is mounted on each substrate by inserting the claws 31a to 31d into holes (locked portions) 41a to 41d and 42a to 42d on the substrate. A state is formed in which the transformer is fitted and attached in the accommodated state. The holes 41a to 41d and 42a to 42d correspond to the fixing means of the present invention.

  The relative positional relationship between these holes is provided according to the position of each claw of the soundproof cover 3. As a result, the holes 41a, 41b, and 41d are provided so as to be positioned on the high pressure side, that is, provided in the rectangular area formed by the soundproof cover storage area 40 so as to be biased toward the high pressure side with respect to the center portion (holes). The same applies to 42a, 42b, and 42d.) As a result, these holes are provided on the silk print area 45 indicating the high pressure area on the substrate.

  On the other hand, the remaining holes 41c and 42c are provided in the primary region 46. At this time, as shown in FIG. 4, the primary winding connecting printed wiring portion 43 for connecting the primary windings of the plurality of inverter transformers in parallel. 44 needs to be provided with a wiring width that allows at least a current of several A order to flow. Therefore, these holes need to be provided so as not to restrict the wiring width of the wiring portions 43 and 44. On the other hand, the high voltage power printed wiring portions 47 and 48 flow at a high voltage (thousands of volts), but the current remains at a few mA, so it can be designed narrower than the wiring width on the primary side. It is possible to design the positions of the holes relatively freely in the peripheral region of the wiring.

  The current capacity required for the printed circuit pattern on the primary side of the inverter circuit board is a design standard established to prevent damage to the printed circuit board due to its current value and expected temperature rise. Is designed. In particular, the larger the current flowing through the wiring, the wider the wiring width is required. If the standard is not observed, the wiring may be discolored or damaged in some cases. For example, when the temperature exceeds 80 ° C., the color changes in a relatively short time, and when the temperature exceeds 120 ° C., peeling of the conductor starts. Normally, the current value is shown for every increase in the conductor temperature. In general, it is preferable to use the temperature increase at 20 ° C. or less, and the standard is about 1 A / mm (35 μm copper foil thickness).

With the main configuration as described above, the soundproof cover for suppressing the sound generated from the inverter transformer can be attached in an appropriate state, that is, without suppressing the design conditions of the inverter circuit board.
In the above embodiment, the example in which the locking portion (claw) and the locked portion (hole) are used as the fixing means for fixing the soundproof cover to the inverter circuit board has been described. The fixing means for the circuit board) is not limited to this, and for example, both may be fixed with an adhesive or the like.

  5 to 9 are diagrams for explaining an example of a procedure for mounting the fluorescent tube in the backlight housing. In each figure, only the fixing structure on one side of the fluorescent tube 21 is shown, but the other side also has the same structure.

  In FIG. 5, a rubber holder 21c is attached to the electrode ends of two fluorescent tubes 21a bundled with a connector 21b via lead wires. A fluorescent tube 21 a bundled with a connector 21 b and having a rubber holder 21 c attached thereto is called a fluorescent tube unit 21, and an electrode portion of the fluorescent unit 21 is housed in a notch 5 a of the lamp holder 5.

  Then, as shown in FIG. 6, each rubber holder 21 c is installed at a predetermined position of the housing 23, and a connector 21 b connected to the electrode of the fluorescent tube 21 a through a plurality of openings 23 a provided on the bottom surface of the housing 23. Is taken out to the back side of the housing 23.

  FIG. 7 is a view showing a state in which the lamp holder 5 is attached to a predetermined position of the housing 23. The lamp holder 5 is attached to the housing 23 with a predetermined structure inside the housing 23. For example, the lamp holder 5 is fitted to a receiving member (not shown) of the lamp holder 5 fixed to the housing 23, so that the lamp 23 is integrally fixed to the housing 23.

  When the lamp holder 5 is attached at a predetermined position, the fluorescent tube connector 21b through the opening 23a of the housing 23 is connected to the inverter circuit board 4 attached to the back surface of the housing 23 via a socket. To do. The positions of the electrodes of the fluorescent tubes 21a are fixed in a state where they are accommodated in the notches 5a provided in the lamp holder 5, and the fluorescent tubes 21a can be arranged with high accuracy at a predetermined interval.

  As shown in FIG. 8, the inverter circuit board 4 is installed on the back side of the housing 23. The inverter circuit board 4 is provided with an inverter transformer 29 and a socket 49 connected to the inverter transformer 29. By attaching the above-described connector 21b to the socket 49, it is possible to form a state where the inverter transformer 29 and the electrode of the fluorescent tube 21a are electrically connected, thereby supplying power from the inverter transformer 29 to the fluorescent tube 21a. It is implemented as follows.

  Then, by attaching the soundproof cover 3 according to the present invention to the hole 41 provided in the inverter circuit board 4, the state shown in FIG. 9 can be formed, and generation of sound from the inverter transformer 29 can be suppressed. Become.

  Next, description will be made on the basis of first to third embodiments described below as embodiments of a backlight device that is optimal for employing such a soundproof cover for an inverter transformer.

First, the first embodiment will be described as follows.
FIG. 10 is a diagram for explaining the arrangement and driving method of the fluorescent lamp of the backlight device according to the first embodiment. FIG. 10A is a diagram for explaining an arrangement of fluorescent lamps and a connection configuration example of an inverter transformer, and FIG. 10B is a diagram for explaining a driving method of the fluorescent lamps at this time.

  In FIG. 10A, a pair of inverter circuit boards 4, a socket 49 mounted on these boards, an inverter transformer 29, and a conductive line for electrically connecting the electrodes of two fluorescent tubes 21a. 6 is provided. On the other hand, the fluorescent tube unit 21 connected to the inverter circuit board 4 includes two fluorescent tubes 21a having both electrodes connected by lead wires, and a connector 21b for holding the lead wires together. One connector 21b is provided at each end of the fluorescent tube 21a. The pair of inverter circuit boards 4 are respectively arranged at positions near the electrodes on both ends of the plurality of fluorescent tube units 21 arranged in parallel on the rear surface of the chassis.

  Then, by connecting one connector 21b to a socket 49 of one of the pair of inverter circuit boards 4, a state of being electrically connected to the inverter transformer 29 via the high voltage wiring line is formed, and the other connector is connected. By connecting 21b to the socket 49 of the other inverter circuit board, it is possible to form a state of being electrically connected to the electrode of the adjacent fluorescent tube 21a via the conductive line 6 described above.

  At this time, as shown in FIG. 10B, the two fluorescent tubes 21a are connected in series in a U shape or a U shape, and are not electrically connected to other fluorescent tubes at this time. By inputting a high-voltage AC voltage signal of about several thousand kV boosted by an inverter transformer to the electrodes of the fluorescent tube, the two fluorescent tubes each start to discharge and cause the internal phosphor to emit light. As a result, the electrode to which the high-voltage AC voltage is input and the electrode to be grounded are arranged adjacent to each other, which reduces the luminance (unevenness of brightness) from the high-voltage part to the low-pressure part of the fluorescent tube, which is common in long fluorescent tubes. On the other hand, by arranging the high-voltage part and the low-pressure part close to each other, the brightness of each other is canceled out, and the entire backlight can contribute to the reduction of luminance unevenness.

  Furthermore, for the fluorescent tube unit adjacent to the fluorescent tube unit, the U-shaped or U-shaped series connection state is inverted with respect to the adjacent fluorescent tube unit. As a result, the present invention exhibits an effect of canceling out luminance unevenness between adjacent fluorescent tube units, and as a result, contributes to further reduction in luminance unevenness (particularly luminance unevenness in the lamp length direction) as a backlight device.

Further, as the second embodiment, the configurations shown in FIGS. 11 and 12 are also conceivable.
11 and 12 are diagrams for explaining the arrangement and driving method of the fluorescent lamp of the backlight device according to the second embodiment. FIG. 11A and FIG. 12 are diagrams for explaining an arrangement of fluorescent lamps and a connection configuration example of an inverter transformer, and FIG. 11B is a diagram for explaining a driving method of the fluorescent lamps at this time.

  In FIG. 11, although the main member configuration is the same as that of the first embodiment, among the electrodes of two fluorescent tubes 21a configured in series connection in a U-shape or a U-shape, each fluorescent tube A high-voltage alternating current signal having the same frequency and phase-inverted from each other is input to each of the electrodes that are not connected to each other, and a longer fluorescent tube unit can be lit by securing a sufficient discharge voltage This is an example. 11 and 12 differ in the configuration of the inverter transformer that is the output source of a pair of high-voltage AC signals that are phase-inverted from each other and output from the inverter circuit board 4, and the one-output type (FIG. 11) and the two-output type ( Each of FIG. 12) is illustrated.

  That is, the one-output type is configured to use two transformers that output a boosted AC voltage at one terminal, while the two-output type is a type that outputs boosted AC voltages at two terminals in opposite phases. The transformer is used.

  In the former example, it is necessary to match the phase of each other's transformer, but as the means, for example, each primary (low voltage) side winding is connected in parallel to the bobbin of each secondary (high voltage) side winding. This can be realized by configuring a transformer in which the winding direction is reversed. In the latter example, it is realized by reversing the winding direction of the secondary (high voltage) side windings around the bobbin.

  With these structures, as shown in FIG. 11B, the two fluorescent tubes can be lit with a sufficient discharge voltage. Further, by configuring the U-shaped or U-shaped series connection state with respect to the adjacent fluorescent tube unit in the inverted state with respect to the adjacent fluorescent tube unit, as in the previous embodiment. Further, it is possible to reduce the luminance unevenness in the lamp length direction.

As a third embodiment, a configuration obtained by further improving the previous embodiment will be described with reference to FIGS.
13 and 14 are diagrams for explaining the arrangement and driving method of the fluorescent lamps of the backlight device according to the third embodiment. FIGS. 13A and 14 are diagrams illustrating an example of the arrangement of the fluorescent lamps and the connection configuration of the inverter transformer, and FIG. 13B is a diagram illustrating the driving method of the fluorescent lamps at this time.

  In the previous embodiment shown in FIG. 11 and FIG. 12 described above, it is possible to further improve the luminance unevenness canceling action with respect to the two adjacent fluorescent tube units. That is, since the luminance distribution in the length direction of each fluorescent tube is configured to be almost the same for every two adjacent tubes, there is a limit to the ability to eliminate luminance unevenness in the lamp arrangement direction.

  Therefore, the conductive lines 6 are adjacent to each other as shown in FIG. 13A for the purpose of eliminating luminance unevenness in the lamp arrangement direction without losing the configuration of the U-shaped or U-shaped series connection state. The fluorescent tubes are not connected to each other. More specifically, the fluorescent tube is blown one by one to constitute a conduction line that connects the electrodes.

  By further providing this configuration, as shown in FIG. 13B, the two fluorescent tubes constituting each fluorescent tube unit cancel each other out so that their luminance distribution is uniform, and the lamp arrangement direction In this configuration, the luminance unevenness canceling performance is further improved.

  14 exemplifies a case where a two-output type is adopted as the type of inverter transformer, as in the example shown in FIG. 12, and the configuration is also the same as that in FIG. . With this configuration, the same effect as that shown in FIG. 13B can be obtained.

  With respect to the third embodiment, when the fluorescent tube unit is mounted on the backlight, it is simply provided to arrange the plurality of units one after another. In addition, it can be said that the configuration of the inverter transformer and the conduction line further enhances the canceling performance of luminance unevenness. In other words, the configuration with higher brightness unevenness canceling function without making the arrangement of fluorescent tubes and so on more complex, it can be produced without losing each of mass production capacity of backlight and optical performance for large screen. The effect can be achieved.

  As mentioned above, the application examples in the backlight device have been illustrated, but these examples are given as examples of longer fluorescent tubes or fluorescent tube units that require longer discharge distances. A higher voltage is naturally required for the discharge voltage from the inverter transformer. Therefore, applying the soundproof cover (soundproof member) of the present invention to these embodiments can achieve a higher effect.

It is sectional drawing which shows the structural example of the liquid crystal display device using the backlight apparatus by this invention. It is an external view for demonstrating the structural example of the soundproof cover used in the backlight apparatus by this invention. It is an external view for demonstrating the structural example of the inverter circuit board (surface) used for the backlight apparatus of this invention. It is an external view for demonstrating the structural example of the inverter circuit board (back surface) used for the backlight apparatus of this invention. It is a figure for demonstrating an example of the procedure which mounts a fluorescent tube in the housing | casing of a backlight. It is a figure for demonstrating the other example of the procedure which mounts a fluorescent tube in the housing | casing of a backlight. It is a figure for demonstrating the other example of the procedure which mounts a fluorescent tube in the housing | casing of a backlight. It is a figure for demonstrating the other example of the procedure which mounts a fluorescent tube in the housing | casing of a backlight. It is a figure for demonstrating the other example of the procedure which mounts a fluorescent tube in the housing | casing of a backlight. It is a figure for demonstrating an example of arrangement | positioning and the drive system of the fluorescent lamp of the backlight apparatus which concerns on a 1st Example. It is a figure for demonstrating an example of arrangement | positioning and the drive system of the fluorescent lamp of the backlight apparatus which concerns on a 2nd Example. It is a figure for demonstrating the other example of arrangement | positioning and the drive system of the fluorescent lamp of the backlight apparatus which concerns on a 2nd Example. It is a figure for demonstrating an example of arrangement | positioning and a drive system of the fluorescent lamp of the backlight apparatus which concerns on a 3rd Example. It is a figure for demonstrating the other example of arrangement | positioning and the drive system of the fluorescent lamp of the backlight apparatus which concerns on a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel, 2 ... Backlight apparatus, 3 ... Soundproof cover (soundproof member), 4 ... Inverter circuit board (light source drive circuit board), 5 ... Lamp holder, 5a ... Notch part, 6 ... Conduction line, 21 ... Fluorescence Lamp (fluorescent tube unit), 21a ... fluorescent tube, 21b ... connector, 21c ... rubber holder, 22 ... reflection sheet, 23 ... casing, 23a ... opening, 24 ... diffusion plate, 25 ... diffusion sheet, 26 ... prism sheet, 27 ... reflective polarizing plate, 29 ... inverter transformer, 31a to 31d ... claw (locking part), 32 ... transformer housing part, 40 ... soundproof cover housing area, 41a to 41d, 42a to 42d ... hole (locked part), 43, 44 ... printed wiring portion for connection between primary windings, 45 ... silk printing (high voltage) region, 46 ... primary side (non-high voltage) region, 47, 48 ... printed wiring portion for high voltage power, 49 ... Tsu door.

Claims (25)

A light source driving circuit board including a transformer for supplying an alternating voltage to a light source,
A light source driving circuit board, comprising: fixing means for fixing a soundproof member for suppressing sound generated from the transformer. The soundproof member includes a transformer housing portion that houses the transformer, and a plurality of locking portions around the opening of the transformer housing portion,
The fixing means includes a plurality of locked portions corresponding to the plurality of locking portions, and in a state where the transformer is accommodated in the transformer accommodating portion, the plurality of locking portions are the plurality of engaged portions. The light source drive circuit board according to claim 1, wherein the light source drive circuit board is locked to a stop portion.   The light source driving circuit board according to claim 2, wherein at least one of the plurality of locked portions is provided on a high voltage region of the light source driving circuit board. A plurality of the transformers are mounted, and a printed wiring portion for connecting the primary windings of each of the plurality of transformers is provided.
The light source driving circuit board according to claim 2, wherein at least one of the plurality of locked portions is provided on a higher voltage region side than the printed wiring portion.   3. The light source according to claim 2, wherein the number of the plurality of locked portions is smaller in the number provided on the non-high voltage region than the number provided on the high voltage region of the light source driving circuit board. Driving circuit board. A plurality of the transformers are mounted, and a printed wiring portion for connecting the primary windings of each of the plurality of transformers is provided.
The number of the plurality of locked portions provided in a region other than the high voltage region is smaller than the number provided in the high voltage region side than the printed wiring portion. Light source drive circuit board.   The light source driving circuit board according to claim 3, wherein the high voltage area is an area silk-printed on at least one surface of the light source driving circuit board.   The light source driving circuit board according to claim 4, wherein the printed wiring portion is provided on a back surface of a mounting surface of the transformer. A soundproof member for suppressing sound generated from a transformer mounted on a light source drive circuit board,
A soundproof member comprising: a transformer accommodating portion that accommodates the transformer; and a fixing means for fixing the transformer to the light source drive circuit board in a state where the transformer is accommodated in the transformer accommodating portion.   The fixing means includes a plurality of locking portions provided around the opening of the transformer accommodating portion, and the plurality of locking portions are provided at a position corresponding to the high voltage region side of the light source driving circuit board. The soundproof member according to claim 9.   The soundproof member according to claim 10, wherein at least one of the plurality of locking portions is provided at a position corresponding to a locked portion provided on a high voltage region side of the light source driving circuit board. .   At least one of the plurality of locking portions is a locked portion provided on a higher voltage region side than the printed wiring portion for connecting the primary windings of the transformer formed by the light source driving circuit board. The soundproof member according to claim 10, wherein the soundproof member is provided at a corresponding position.   The soundproof member according to claim 10, wherein the number of the plurality of locking portions locked in the non-high pressure region is smaller than the number locked in the high pressure region of the light source driving circuit board. .   The plurality of locking portions are regions other than the high voltage region than the number locked to the high voltage region side from the printed wiring portion for connecting the primary windings of the transformer formed by the light source driving circuit board. The soundproofing member according to claim 10, wherein the number of the soundproofing members is smaller.   The soundproof member according to any one of claims 9 to 14, wherein the transformer housing portion has a substantially rectangular parallelepiped space formed therein.   A backlight device comprising the light source driving circuit board according to claim 1 and the soundproof member according to any one of claims 9 to 15. A plurality of light sources, a transformer for supplying an alternating voltage to the plurality of light sources, a light source driving circuit board on which the transformer is mounted, and a soundproof member for suppressing sound generated from the transformer mounted on the light source driving circuit board. Prepared,
The soundproof member includes a transformer housing portion that houses the transformer, and a plurality of locking portions around the opening of the transformer housing portion,
The light source drive circuit board includes a plurality of locked portions corresponding to the plurality of locking portions, and the plurality of locking portions are in the plurality of locked portions in a state where the transformer is accommodated in the transformer accommodating portion. A backlight device that is locked to the locking portion.   The backlight device according to claim 17, wherein the light source is controlled to be turned on or off by a substantially rectangular light control signal.   The backlight device according to claim 17, wherein at least one of the plurality of locked portions is provided on a high voltage region of the light source driving circuit board. The light source drive circuit board includes a printed wiring portion for mounting a plurality of the transformers and connecting primary windings formed by the plurality of transformers,
18. The backlight device according to claim 17, wherein at least one of the plurality of locked portions is provided on a higher voltage region side than the printed wiring portion.   18. The back according to claim 17, wherein the number of the plurality of locked portions is less on the non-high-voltage region than on the high-voltage region of the light source driving circuit board. Light equipment. The light source drive circuit board includes a printed wiring portion for mounting a plurality of the transformers and connecting primary windings formed by the plurality of transformers,
The number of the plurality of locked portions provided in a region other than the high-voltage region is smaller than the number provided in the high-voltage region side than the printed wiring portion. Backlight device.   The backlight device according to any one of claims 19 to 22, wherein the high-voltage region is a region silk-printed on at least one surface of the light source driving circuit board.   The backlight device according to claim 20 or 22, wherein the printed wiring portion is provided on a back surface of a mounting surface of the transformer.   25. A liquid crystal display device comprising: the backlight device according to claim 16; and a liquid crystal panel illuminated by the backlight device.

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