JP2008177016A - LIGHTING DEVICE AND DISPLAY DEVICE HAVING THE SAME - Google Patents

Abstract

An illumination device capable of efficiently constructing a uniform and high-luminance light-emitting surface over a wide area.
A backlight chassis 11 provided on the back side of a display panel 3 is divided into two in a long side direction or a short side direction, and discharge lamps 7 and 8 are orthogonal to the divided direction in these divided regions, respectively. The two electrodes 7b and 8b of the two discharge lamps 7 and 8 that are adjacent in parallel are connected in common, and the other electrodes 7a and 8a are connected to the inverter circuit.
[Selection] Figure 1

Description

  The present invention relates to an illuminating device suitably used for a display device such as a liquid crystal display device.

  As an example of a display device, for example, a liquid crystal display device including a liquid crystal display panel generally has a lighting device disposed on the back side of the liquid crystal display panel. This illuminating device is usually provided with a cold cathode type discharge lamp as a light source, and the characteristics of light emitted from the discharge lamp are adjusted to irradiate the back side of the display panel. The irradiated light passes through the display panel, whereby an image is displayed on the front side of the display panel.

  FIG. 5 is an exploded perspective view showing the main part of the structure of a liquid crystal display device generally used conventionally. The illustrated liquid crystal display device 31 includes a bezel 32, a display panel 33, and a lighting device 34. The bezel 32 is a member serving as a frame of the display panel 33. The display panel 33 is formed by bonding two glasses and sealing liquid crystal therebetween.

  The illustrated lighting device 34 includes a frame 35, optical sheets 36, a discharge lamp 37, a reflecting plate 40, a backlight chassis 41, a side holder 42, and an inverter circuit board 43. The frame 35 has a frame shape, and is for fixing the optical sheets 36 to the mounting surfaces of the backlight chassis 41 and the side holders 42. The optical sheets 36 are for adjusting the characteristics of light incident on the display panel 33 from the discharge lamp 37.

  The reflector 40 laid under the discharge lamp 37 is for reflecting the light emitted from the discharge lamp 37 to the display panel 33 side. The backlight chassis 41 and the side holder 42 are members for forming a discharge lamp housing portion that houses a plurality of discharge lamps 37 in parallel.

  An inverter circuit board 43 that generates a high-voltage pulse voltage that drives the discharge lamp 37 is provided on the back surface of the backlight chassis 41. A control circuit board 44 that controls the display panel 33 is also provided on the back surface of the backlight chassis 41.

  In such an illuminating device 34, the discharge lamp 37, which is a light source, is driven by a one-side high-pressure driving method in which one electrode is a high-voltage side and the other electrode is a low-voltage side by an inverter circuit 51, as shown in FIG. In general, the metal backlight chassis 41 is at ground potential. When the discharge lamp 37 is driven in this configuration, the backlight chassis 41 serves as a proximity conductor, and a stray capacitance Cs is generated between the discharge lamp 37 and the backlight chassis 41. Therefore, a part of the current flowing in the discharge lamp 37 flows as a leakage current is to the backlight chassis 41 which is a proximity conductor. Since the leakage current is increases as the discharge lamp 37 becomes longer, it is known that a luminance gradient that darkens from the high pressure side to the low pressure side is generated due to the current difference between the high pressure side and the low pressure side.

  In recent years, discharge lamps as light sources have become longer along with the increase in the screen size of liquid crystal display devices used in liquid crystal televisions and the like, and the luminance gradient of such discharge lamps, for example, differs in brightness between the left and right of the display screen. There was a problem of appearing.

  Moreover, in the general connection form which returns the low voltage | pressure side of a discharge lamp with a return line, since the board | substrate for return lines is required, this board | substrate became the obstacle of size reduction of an illuminating device. Furthermore, the work of extending the return line to the inverter circuit board disposed on the high-pressure side of the discharge lamp is also complicated.

  Therefore, as shown in FIG. 7, the two discharge lamps 37 and 38 are connected by the low pressure side 37b and 38b, and the high voltage side 37a and 38a of each discharge lamp 37 and 38 are alternately reversed in phase from the inverter circuit 52. A method of applying high voltages Va and Vb has been proposed. As a result, the above-described luminance gradient is alleviated and the return line of the discharge lamp becomes unnecessary. In addition, the following patent documents 1-3 are mentioned as a prior art document relevant to this invention.

JP 10-143089 A JP 2002-278471 A JP 2004-325671 A

  However, even in the method of lighting the discharge lamp by alternately applying a high voltage of opposite phase to the both ends of the two U-shaped discharge lamps in series, the screen of the liquid crystal display device is further increased. With the accompanying increase in the length of the discharge lamp, the problem of the brightness gradient of becoming darker from the high pressure side toward the low pressure side has become prominent.

  Therefore, the problem to be solved by the present invention is to provide an illumination device capable of efficiently constructing a uniform and high-luminance light-emitting surface over a wide area, and a display device including the illumination device.

  In order to solve the above problems, a lighting device for a display device according to the present invention is a lighting device in which a plurality of discharge lamps are arranged in a backlight chassis provided on the back side of a display panel, and the backlight The inside of the chassis is divided into at least two in the long side direction or the short side direction, and the discharge lamps are juxtaposed in the direction orthogonal to the dividing direction in each of the divided regions, and at least two of the discharges arranged in parallel and adjacent to each other. The gist of the invention is to commonly connect each electrode of the lamp as a set and connect the other electrode to an inverter circuit.

  In this case, it is preferable that the respective electrodes of the pair of discharge lamps adjacent to each other across the boundary line of the divided area are electrodes connected in common or electrodes connected to an inverter circuit.

  In addition, the commonly connected electrodes of the set of discharge lamps near the boundary line of the divided area or the electrodes connected to the inverter circuit are arranged in a staggered manner with respect to the boundary line of the divided area It is good to make it. Furthermore, it is preferable that the commonly connected electrodes of the pair of discharge lamps adjacent to each other across the boundary line of the divided region are further connected in common. And it is good to set it as the structure which is a display apparatus provided with such an illuminating device.

  According to the illumination device having the above configuration, the inside of the backlight chassis is divided into at least two in the long side direction or the short side direction, and the discharge lamps are juxtaposed in the direction perpendicular to the dividing direction in these divided regions, Since one electrode of each of a pair of at least two discharge lamps arranged in parallel is connected in common and the other electrode is connected to an inverter circuit, the length of the discharge lamp used is shorter than in the prior art. Therefore, it becomes possible to reduce the luminance gradient of darkening from the high pressure side to the low pressure side of the discharge lamp. Thereby, a uniform high-luminance light emitting surface can be formed in a wide range.

  In this case, if each electrode of the pair of discharge lamps adjacent to each other across the boundary line of the divided area is configured to be a commonly connected electrode or electrodes connected to an inverter circuit, Wiring work to the discharge lamp arranged in the light chassis can be performed efficiently. In particular, when the commonly connected electrodes are adjacent to each other at the boundary line of the divided region, the insulation distance can be reduced because they are on the low-pressure side. The dark part due to the non-light emitting part can be reduced.

  In addition, the commonly connected electrodes of the set of discharge lamps near the boundary line of the divided area or the electrodes connected to the inverter circuit are arranged in a staggered manner with respect to the boundary line of the divided area By doing so, the non-light-emitting portion of the discharge lamp is complemented by the light-emitting portion of the other discharge lamp, so that a uniform and high-luminance light emitting surface can be formed over a wide range. Furthermore, if the configuration is such that the commonly connected electrodes of the pair of discharge lamps adjacent to each other across the boundary line of the divided region are further connected in common, the wiring to the discharge lamp is simplified. This is possible. And, if such a lighting device is incorporated into a display device, for example, it is prevented that it appears as a difference in brightness on the left and right of the display screen.

  Embodiments of a display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view schematically showing a main part of a structure of a display device according to an embodiment of the present invention. FIG. 2 shows a circuit configuration in which the low-voltage side electrodes shown in FIG. 1 are connected in common and are driven by applying a high voltage to the high-voltage side electrodes of two U-shaped discharge lamps 7 and 8 in series. FIG. 3 is a view showing an arrangement configuration of a lamp group in which discharge lamps 7 and 8 are paired in a chassis 11.

  A liquid crystal display device 1 shown in FIG. 1 includes a bezel 2, a display panel 3, and a lighting device 4. The bezel 2 is a member serving as a frame of the display panel 3, and the display panel 3 is formed by bonding two glasses and sealing liquid crystal therebetween.

  The illumination device 4 includes a frame 5, optical sheets 6, a pair of discharge lamps 7 and 8, a reflector 10, a backlight chassis 11, a side holder 12, and inverter circuit boards 13 and 13. The frame 5 has a frame shape, and is used to fix the optical sheets 6 to the mounting surface of the backlight chassis 11 and the side holder 12. The optical sheets 6 are for adjusting the characteristics of light incident on the display panel 3 from the discharge lamps 7 and 8, and include, for example, a diffusion sheet, a lens sheet, a polarization reflection sheet, a diffusion plate, and the like.

  As shown in FIG. 2, the inside of the backlight chassis 11 is divided into two by a dividing boundary line 18 in the left-right direction, and the discharge lamps 7 and 8 are vertically divided in these divided regions 18a and 18b, respectively, perpendicular to the dividing direction. Are in parallel. Then, each of the electrodes 7b and 8b of the two discharge lamps 7 and 8 adjacent in parallel is connected in common, and the other electrodes 7a and 8a are connected to the inverter circuit board 13 provided with the inverter circuit 22. It is connected.

  As shown in the figure, the discharge lamps 7 and 8 are fixed to the backlight chassis 11 by attaching electrode holders 15 and 16 to the end portions of the high-pressure sides 7 a and 8 a that are driven at high pressure by the inverter circuit board 13. . The electrodes of the low-pressure sides 7b and 8b opposite to the high-pressure sides 7a and 8a of the discharge lamps 7 and 8 are commonly connected to form a connecting portion 9.

  The reflecting plate 10 laid under the discharge lamps 7 and 8 is for reflecting the light emitted from the discharge lamps 7 and 8 to the display panel 3 side. The backlight chassis 11 and the side holder 12 are members for forming a discharge lamp housing portion that houses a plurality of discharge lamps 7 and 8 that are paired in parallel. In this case, the backlight chassis 11 is formed in a substantially box shape by sheet metal processing of a metal plate material, and constitutes a bottom portion of the discharge lamp housing portion and a side wall portion on the long side. The side holder 12 is a white resin member, and similarly forms a side wall portion on the short side of the discharge lamp housing portion.

  Further, on the back surface of the backlight chassis 11, inverter circuit boards 13 and 13 for generating a high-voltage pulse voltage for driving the discharge lamps 7 and 8 and inverter circuit board covers 13a and 13a covering the inverter circuit boards 13 and 13 are provided. Is provided. A control circuit board 14 that controls the display panel 3 and a control circuit board cover 14 a that covers the control circuit board 14 are also provided on the back surface of the backlight chassis 11.

  Next, the inverter circuit 22 shown in FIG. 2 that is driven by alternately applying high voltages having opposite phases to both end electrodes of the two series discharge lamps 7 and 8 having such a configuration will be described. The inverter circuit 22 provided on the inverter circuit board 13 is for applying a high voltage having opposite phases alternately to both end electrodes of two U-shaped discharge lamps 7 and 8 in series, and is input from the outside. A power drive unit 22b that switches a DC power source (for example, 12V) to convert it to an AC pulse voltage, an oscillation control unit 22a that controls the switching operation of the power drive unit 22b, and an AC output from the power drive unit 22b And a power converter 22c that boosts the pulse voltage to a high voltage of several hundred volts (V) or more and supplies it to the discharge lamps 7 and 8.

  As shown in FIG. 2, the interior of the backlight chassis 11 is divided into left and right parts, and the discharge lamps 7 and 8 are arranged in parallel in the vertical direction perpendicular to the dividing direction in these divided regions 18a and 18b, respectively. By using a configuration in which at least two discharge lamps 7 and 8 adjacent to each other are commonly connected to one electrode 7b and 8b, and the other electrode 7a and 8a is connected to the inverter circuit 22, it is used more than the prior art. The length of the discharge lamp can be shortened, and it is possible to reduce the luminance gradient of darkening from the high pressure side to the low pressure side of the discharge lamp. Thereby, a uniform high-luminance light emitting surface can be formed in a wide range.

  In this case, the commonly connected electrodes 7b and 8b of the pair of discharge lamps 7 and 8 adjacent to each other with the division boundary 18 interposed therebetween, that is, the connecting portions 9 and 9 sandwich the division boundary 18 as illustrated. In the case where they are adjacent to each other, because they are on the low pressure side, it is possible to reduce the dark distance due to the non-light emitting portion of the discharge lamp by reducing the insulation distance and bringing the electrodes closer to each other. As shown in FIG. 3, if the connecting portions 9 and 9 of FIG. 2 are further connected in common to form a new connecting portion 19, wiring to the electrodes 7b and 8b of the discharge lamps 7 and 8 is simplified. be able to.

  Further, as shown in FIG. 4, in the vicinity of the dividing boundary line 18, a set of commonly connected connecting portions 9 of the discharge lamps 7 and 8 in the left divided area 18a and the discharge lamps 7 and 8 in the right divided area 18b. If the commonly connected connecting portions 9 are arranged in a staggered manner with respect to the dividing boundary line 18, the non-light emitting portion of the discharge lamp is complemented with the light emitting portion of the other discharge lamp. Therefore, a uniform and high-luminance light emitting surface can be formed over a wide range. The discharge lamps 7 and 8 in this case are a pair of short and long ones as shown in the figure.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to such Embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in a various aspect. For example, in the above embodiment, the configuration in which the discharge lamp is arranged by dividing the inside of the backlight chassis 11 into two in the long side direction as shown in FIG. 1 has been described, but it is divided into three parts, four parts, five parts,. -You may do and may divide | segment into a short side direction, It is not limited to the said embodiment.

It is a disassembled perspective view which shows schematic structure of the display apparatus which concerns on one Embodiment of this invention. FIG. 2 is a diagram showing an arrangement configuration of discharge lamps in a backlight chassis and a schematic configuration of a power source for applying a high voltage to each discharge lamp in the pair shown in FIG. 1. It is the figure which showed the modification of the connection structure of the discharge lamp shown in FIG. It is the figure which showed the modification of the arrangement configuration of the discharge lamp shown in FIG. It is a disassembled perspective view which shows schematic structure of the display apparatus used conventionally. It is the figure which showed the luminance distribution of the axial direction at the time of driving the discharge lamp shown in FIG. It is the figure which showed schematic structure of the lighting method which applies the high voltage of an antiphase alternately to the both-ends electrode of the two series discharge lamp which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Bezel 3 Display panel 4 Illumination device 5 Frame 6 Optical sheet 7 Discharge lamp 7a High pressure side 7b Low pressure side 8 Discharge lamp 8a High pressure side 8b Low pressure side 9 Connecting part 10 Reflecting plate 11 Backlight chassis 12 Side holder 13 Inverter circuit board 13a Inverter circuit board cover 14 Control board 14a Control board covers 15 and 16 Electrode holder 18 Dividing boundary lines 18a and 18b Dividing area 19 Connecting part 22 Inverter circuit 22a Oscillation control part 22b Power driving part 22c Power supply converting part

Claims (10)

  A lighting device in which a plurality of discharge lamps are arranged in a backlight chassis provided on the back side of a display panel, the interior of the backlight chassis being divided into at least two in the long side direction or the short side direction, and these divisions The discharge lamps are juxtaposed in the direction perpendicular to the dividing direction in each of the regions, and at least two of the discharge lamps arranged in parallel and adjacent to each other are connected in common, and the other electrode Is connected to an inverter circuit.   2. The electrodes of the discharge lamp sets adjacent to each other across a boundary line of the divided areas are commonly connected electrodes or electrodes connected to an inverter circuit. The lighting device described.   The commonly connected electrodes of the set of discharge lamps near the boundary line of the divided area or the electrodes connected to the inverter circuit are arranged in a staggered manner with respect to the boundary line of the divided area. The lighting device according to claim 1 or 2.   4. The lighting device according to claim 2, wherein the commonly connected electrodes of the pair of discharge lamps adjacent to each other across the boundary line of the divided region are further connected in common.   A display device comprising the illumination device according to claim 1.   A lighting device in which a plurality of discharge lamps are arranged in a backlight chassis provided on the back side of a display panel, wherein the backlight chassis is divided into two in the long side direction or the short side direction, and these are divided. The discharge lamps are juxtaposed in a direction orthogonal to the dividing direction in each region, and one of the electrodes of the two adjacent discharge lamps arranged in parallel is commonly connected, and the other electrode is connected to the inverter. A lighting device connected to a circuit.   The electrodes of the discharge lamp set adjacent to each other across a boundary line of the divided regions are commonly connected electrodes or electrodes connected to an inverter circuit. Lighting equipment.   The commonly connected electrodes of the set of discharge lamps near the boundary line of the divided area or the electrodes connected to the inverter circuit are arranged in a staggered manner with respect to the boundary line of the divided area. The lighting device according to claim 6 or 7.   9. The lighting device according to claim 7, wherein the commonly connected electrodes of the pair of discharge lamps adjacent to each other across a boundary line of the divided regions are further connected in common.   A display device comprising the illumination device according to claim 6.

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