JP2008171710A - Backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight device using rare gas discharge lamps in which flickering at the light-emitting face of the backlight device is reduced, total optical amount fluctuations are suppressed, and further, power loss is reduced. <P>SOLUTION: The backlight device is equipped with light source lamps arranged a plurality of pieces in a case and a sheet body which is arranged so as to cover the opening part of the case and has an optical correction function. The light source lamp consists of a rare gas discharge lamp which is equipped with a straight-tube shape arc tube in which a rare gas is filled, a phosphor layer formed on the inner face of the arc tube, a pair of external electrodes arranged so as to extend in tube axial direction at the outer face of the arc tube, an easy-starting portion formed on the inner circumference face near one of the end part of the arc tube. When a plurality of rare gas discharge lamps are arranged, the direction arranged on the lamp axis of the easy-starting portions is reversely arranged in the case. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlight device equipped with a rare gas discharge lamp.

  2. Description of the Related Art Conventionally, a so-called direct-type backlight device is generally used as a backlight device that is a lighting device installed on the back of a liquid crystal display device using a liquid crystal display body or the like or an advertising billboard. As a light source used in the backlight device, a light source in which elongated tubular fluorescent lamps are arranged side by side is well known.

  FIG. 6 shows such a backlight device according to the prior art. The backlight device 20 includes a plurality of straight tubular light source lamps 80, a rectangular casing 21, and an inner surface of the casing 21, and is provided behind the light source lamps 80 in the light irradiation direction. A reflection sheet 22 is provided. In this example, for example, 16 light source lamps 80 are arranged in parallel at positions spaced apart from each other, and both ends are held by holding members (not shown).

  A diffusion plate 41, a diffusion sheet 42, and a directivity control sheet 43 in the opening 21A on the front side in the light emission direction of the casing 21 are the diffusion plate 41, the diffusion sheet 42, The directivity control sheets 43 are stacked in this order. The diffusing plate 41 is formed of a diffusing object made of an opaque resin or the like, and diffuses and transmits the light emitted from the light source lamp 80. A light shielding material having a low transmittance such as barium sulfate or titanium oxide is uniformly kneaded inside the diffusion plate 41 so as to make the luminance distribution of the emitted light uniform. The diffusion sheet 42 is made of a translucent resin sheet having a diffusion material, and further diffuses the transmitted light from the diffusion plate 41. The directivity control sheet 43 is composed of a prism sheet formed of a highly permeable material such as polyolefin resin, polycarbonate resin, acrylic resin, or polyethylene terephthalate resin. The diffusion plate 41 and the diffusion sheet 42 are uniform. The converted light has directivity to improve the brightness in front of the screen.

  The sheet body 40 having a light correction function constituted by the diffusion plate 41 and the like diffuses the direct light from the light source lamp 80, has directivity, and is arranged so as to have a uniform luminance with respect to the projection surface. It controls the light distribution. As the light source lamp 80, specifically, a cold cathode type low-pressure mercury lamp 81 is used. A characteristic of this type of lamp is that light is emitted from the entire circumference of the tubular portion. The light emitted from the cold cathode type low-pressure mercury lamp 81 is directly incident on the sheet body 40 directly above, and is also reflected by the reflection sheet 22 disposed behind and incident on the sheet body 40.

  Thus, the cold cathode fluorescent lamp 81 (hereinafter referred to as CCFL) is used as the light source lamp 80 according to the conventional backlight device 20. In the CCFL, mercury and a rare gas are enclosed in an arc tube made of an elongated glass tube, a phosphor is applied to the inner surface, and a pair of internal electrodes are provided at both ends of the arc tube. This CCFL excites a phosphor with ultraviolet light having a wavelength of 254 nm obtained by low-pressure mercury vapor discharge to obtain visible light.

  Such a lamp using mercury has a drawback that it takes time for the mercury enclosed therein to evaporate at a low temperature, resulting in poor luminous flux rise characteristics. In addition, the use of mercury, which has a large environmental load, has recently been regarded as a problem, and an alternative to a lamp having a low environmental load is being studied and explored.

Under such circumstances, as a lamp that does not use mercury and has a low environmental load, for example, Patent Document 1 discloses a lamp that emits light by exciting a phosphor with light from a low-pressure Xe gas discharge. Specifically, it has an arc tube made of a dielectric material such as glass, and a pair of external electrodes extending in the longitudinal direction of the arc tube are arranged on the outer surface of the arc tube so as to be spaced apart from each other. A phosphor layer is formed on the surface. When a voltage is applied to the external electrode, a discharge is generated with a dielectric interposed between the electrodes, and excimer emission with a wavelength of 172 nm is obtained by Xe gas. This ultraviolet light is converted into visible light by exciting the phosphor. . The lamp having such a configuration is called a rare gas discharge lamp.
The rare gas discharge lamp has good start-up characteristics and does not use mercury unlike CCFL, and is considered suitable from the viewpoint of environmental load.

  However, the cold cathode fluorescent lamp has the advantage that it can be started at a relatively low voltage. This is because the Penning effect between the sealed gases such as Ne—Ar and Ar—Hg is used to facilitate the start of discharge. On the other hand, since the rare gas discharge lamp uses only Xe as the luminescent species, the Penning effect cannot be expected, resulting in a problem that the starting voltage becomes very high. For this reason, Patent Document 2 discloses providing an easily startable portion on the inner peripheral portion of the arc tube. With this technology, the voltage applied between the external electrodes can be effectively capacitively coupled through the tube wall of the glass tube constituting the arc tube, thereby facilitating starting.

By the way, the rare gas discharge lamp generates a discharge by applying a high frequency high voltage. In the rare gas discharge lamp provided with the easily startable portion, the discharge is performed in conjunction with the ON / OFF of the high frequency inverter. Has occurred and disappeared. Specifically, corresponding to a frequency of about 100 Hz, when the discharge spreads from the easily startable portion in the lamp axis direction of the rare gas discharge lamp, the whole emits light, the inverter is turned off, and the power supply is stopped. The rare gas discharge lamp is also turned off.
JP-A-9-120799 JP-A-10-188910 Japanese Patent No. 3686793

  Here, the present inventors have developed a backlight device in which a rare gas discharge lamp is arranged. The arrangement of the backlight device is shown in FIG. In the backlight device 70 of FIG. 7, a plurality of the rare gas discharge lamps 2 arranged in parallel are arranged in an easily startable part formed at one end of the rare gas discharge lamp 2 because of the ease of arrangement and connection of the high-frequency transformer 71. It is conceivable to arrange the 16 arrangement directions in one direction. (FIG. 7-a) In FIG. 7, the easily startable portion 16 arranged in one direction is formed on the inner peripheral surface in the vicinity of one end of the arc tube that forms the rare gas discharge lamp 2. In addition, a conductive substance such as carbon is applied and formed along the inner surface of the arc tube so that the cross section perpendicular to the tube axis has a ring shape or a C shape. The easily startable portion 16 is provided with an overlapping portion between a part of a pair of external electrodes arranged on the outer surface of the arc tube and the glass constituting the arc tube. With such a configuration, when a high frequency voltage is applied to the external electrode provided on the outer surface of the arc tube, the rare gas in the vicinity of the easily startable portion 16 can be easily ionized and discharge can be started even at a low voltage. It has the effect of.

  However, as shown in FIG. 7A, a new problem arises when the easily startable portions 16 are arranged together in one direction, for example, on the left side of the backlight device 70. This will be described with reference to FIG. FIG. 7B schematically shows how the discharge plasma generated from the easily startable portion 16 of the rare gas discharge lamp 2 spreads. The easily startable portions 16 provided at one end of the rare gas discharge lamps 2 arranged in parallel are collectively arranged on the left side of the drawing. In this figure, the state immediately after the start of the rare gas discharge lamp 2 is shown, and the discharge plasma 72 generated from the easily startable portion 16 gradually grows in the direction indicated by the arrow, The gas discharge lamp 2 extends to the entire arc tube. Here, the rare gas discharge lamp 2 is characterized in that, by applying a high-frequency voltage, the light is repeatedly turned on and off whenever the applied polarity of the high-frequency voltage changes. That is, the rare gas discharge lamp 2 is repeatedly turned on and off in accordance with the frequency of the applied high frequency, and each time, the arrow in the drawing of the discharge plasma 72 starting from the easily startable portion 16 is shown. Growth in the direction is repeated. Further, the backlight device 70 as a whole may be used in a dimming mode by making it variable, for example, by reducing the amount of light emitted from the rare gas discharge lamp 2. In such a case, the rare gas discharge lamp 2 is used by burst lighting. This adjusts the width of the OFF time of the rare gas discharge lamp 2 corresponding to the low-frequency ON-OFF signal, and the high-frequency voltage is applied during the ON time, and lighting and blinking are repeated. In the case of lighting in this dimming mode, the rare gas discharge lamp 2 is not lit during the OFF time, and the discharge plasma 72 is directed in the axial direction from the easily startable portion 16 when the ON time starts. grow up. In this case, since there is a low-frequency extinguishing time, the fluctuation in the amount of light during the growth of the discharge plasma 72 is more emphasized.

  As described above, the discharge plasma 72 starting from the easily startable portion 16 spreads in correspondence with the frequency of the high frequency supplied to the rare gas discharge lamp 2 and the lighting mode. Flickering occurred. In particular, when the backlight device 70 is used as a backlight light source in a liquid crystal television or the like, if the light amount is reduced in the dimming mode or the like, there is a problem that the light amount fluctuation as a whole screen becomes remarkable.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to reduce flickering of a light emitting surface in a backlight device using a rare gas discharge lamp. It is another object of the present invention to provide a backlight device that can suppress fluctuations in the amount of light over the entire screen even when the amount of light is reduced in a dimming mode or the like. Furthermore, it is providing the backlight apparatus which reduced power loss.

  The backlight device of the present invention has a light emitting opening, a housing in which a reflector is disposed, and a plurality of light sources disposed in parallel to and spaced from each other inside the housing. A backlight device comprising: a lamp; and a sheet body having a light correction function arranged so as to cover an opening of the housing, wherein the light source lamp is a straight tube in which a rare gas is sealed. An arc tube, a phosphor layer formed on the inner surface of the arc tube, a pair of external electrodes disposed on the outer surface of the arc tube so as to extend in the tube axis direction, and near one end of the arc tube And a noble gas discharge lamp having an easily startable part formed on the inner peripheral surface, and when arranging a plurality of the noble gas discharge lamps in parallel, on the lamp shaft on which the easily startable part is arranged These directions are reversed and arranged in the casing.

  In the above-described configuration, the rare gas discharge lamp includes a plurality of transformers that supply power to a power supply unit provided at one end of the rare gas discharge lamp, and a plurality of rare gas discharges connected to the transformer. A lamp group comprising lamps is provided, and the position of the easily startable portion of the rare gas discharge lamp in the lamp group is an end opposite to the side connected to the transformer, and each adjacent lamp group In each case, the direction on the lamp axis where the easily startable portion is arranged is reversed.

  Alternatively, the plurality of rare gas discharge lamps arranged in the casing are arranged in parallel to each other, and an easily startable portion is provided at one end in the lamp tube axial direction, and each of the adjacent rare gas discharges For each lamp, the direction on the lamp axis where the easily startable portion is arranged is reversed.

  According to the first aspect of the present invention, when a plurality of the rare gas discharge lamps are arranged in parallel, the direction on the lamp shaft where the easily startable part is arranged is reversed in the casing. Therefore, the flicker of the backlight device can be reduced. In addition, since a rare gas discharge lamp is used as the light source lamp, it is not necessary to use mercury as a light emitting element, and a backlight device with a low environmental load can be provided.

  According to the invention described in claim 2, since the transformer is provided for each lamp group composed of a plurality of rare gas discharge lamps, the number of transformers arranged in the backlight device is small, and the overall device is Lightweight and compact. Further, since the transformer is disposed on the opposite side of the direction of the noble gas discharge lamp on the lamp axis where the easily startable part is disposed, the power loss at the easily startable part is reduced. There is work. Furthermore, since the direction on the lamp axis where the easily startable portion is arranged for each lamp group is reversed, flickering can be reduced as a whole backlight device.

  According to the third aspect of the present invention, since the direction on the lamp axis where the easily startable part is arranged is reversed for each rare gas discharge lamp arranged in the housing, the liquid crystal television or the like When used as a backlight light source, the screen does not flicker. Furthermore, even if the light amount is reduced in the dimming mode or the like, fluctuations in the light amount over the entire screen can be suppressed.

  The light source device of the present invention is a light source device in which a plurality of rare gas discharge lamps each having an easily startable part at one end of a lamp tube shaft are arranged in parallel. Each of the lamp groups including the gas discharge lamps or each of the rare gas discharge lamps is reversely arranged. With such a configuration, when the light source device of the present invention is used for a backlight light source or the like, the direction in which discharge plasma grows at the start is not biased as a whole, and flicker can be suppressed during image display. Is. Hereinafter, the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view schematically showing the configuration of the backlight device 1 of the present invention. The backlight device 1 includes a rectangular casing 21 having an opening 21A that forms a light projection opening above the plane of FIG. 1, and a plurality of straight tubular light source lamps arranged in the casing 21. 10 and a reflection sheet 22 provided behind the light source lamp 10 with respect to the light irradiation direction. In the present embodiment, for example, the eight light source lamps 10 are arranged so as to extend in parallel at positions spaced apart from each other (the interval between the light source lamps 10 is 50 mm). The eight rare gas discharge lamps 2 are arranged such that the surface on which no external electrode is provided faces the opening 21A. Further, a reflective sheet 22 having a visible light reflectance of 95% is laid 15 mm away from the light source lamp 10 disposed inside the housing 21.

  An optical correction sheet 40 is disposed on the side of the opening 21 </ b> A of the casing 21 so as to cover the entire opening 21 </ b> A of the casing 21. The sheet body 40 is for uniformizing the emitted light from the light emitting surface or increasing the brightness, and specifically, a diffusion plate for diffusing the emitted light to equalize the luminance of the light emitting surface. 41, a diffusion sheet 42 for further diffusing and uniformizing the light emitted from the diffusion plate 41, a prism sheet or the like for improving the luminance by providing directivity to the outgoing light emitted from the diffusion sheet 42 The directivity control sheets 43 are stacked in order with respect to the light irradiation direction.

  In the backlight device 1 used for a liquid crystal television or the like, the sheet body 40 is configured by combining such sheets as necessary. Examples of the material constituting the diffusion plate 41 and the diffusion sheet 42 include those that are preferably used. As the diffusing plate 41, a polycarbonate resin or the like whose surface is processed with irregularities can be used. Further, as the diffusion sheet 42, a transparent resin formed of polyethylene terephthalate resin, polycarbonate resin, acrylic resin, or the like is used as a base material, and the base material surface can be used with a diffusing agent or uneven processing. The directivity control sheet 43 may be a prism sheet formed of a highly permeable material such as polyolefin resin, polycarbonate resin, acrylic resin or polyethylene terephthalate resin. These sheet bodies 40 are disposed, for example, with a gap of 20 mm from the rare gas discharge lamp 2 disposed in the housing 21.

  FIG. 2 shows a configuration diagram of the rare gas discharge lamp 2 used as the light source lamp 10 shown in FIG. 1 and a cross-sectional view of the easily startable portion 16 side formed in the rare gas discharge lamp 2. . The light source lamp 10 includes an external electrode type rare gas discharge lamp 2 and includes a straight tube arc tube 11 having both ends sealed, for example, glass tubes, as shown in FIG. A phosphor layer 12 is formed over substantially the entire inner surface of the. In addition, a pair of external electrodes 13a and 13b extending in parallel to each other in the tube axis direction are formed on the outer surface of the arc tube 11, and a rare gas is sealed inside the arc tube 11. .

  In addition, an easily startable portion 16 is formed on the inner peripheral surface near one end portion of the arc tube 11 forming the rare gas discharge lamp 2, and a conductive substance such as carbon is applied to the arc tube 11. A coating is formed along the inner surface so that the shape in a cross section perpendicular to the tube axis is a ring shape or a C shape. The easily startable portion 16 is provided with an overlapping portion with a part of the pair of external electrodes 13a and 13b arranged on the outer surface of the arc tube and the glass constituting the arc tube 11 interposed therebetween. With such a configuration, when a high frequency voltage is applied to the external electrode provided on the outer surface of the arc tube 11, the rare gas in the vicinity of the easily startable portion 16 is easily ionized and discharge starts even at a low voltage. It has the effect of being able to. In FIG. 2, the easily startable portion 16 overlaps both of the external electrodes 13a and 13b with the glass constituting the arc tube 11 interposed therebetween. Has an effect.

Further, since the phosphor layer 12 is configured to emit light from the entire circumference of the arc tube 11, the film thickness is desirably 20 μm or less. Specifically, in this example, as the phosphor layer, a red phosphor is europium activated yttrium oxide phosphor (Y ₂ O ₃ : Eu), and a green phosphor is cerium terbium activated lanthanum phosphate phosphor (LaPO). ₄ : Ce, Tb), a blue phosphor is a europium activated barium magnesium aluminate phosphor (BaMgAl ₁₀ O ₁₇ : Eu), these are mixed, coated, dried and fired, and the light emission It is formed over the entire circumference of the inner peripheral surface of the tube 11. The arc tube 11 in this embodiment is made of barium glass, and has a tube outer diameter of 9.8 mm, an inner diameter of 9 mm, and a total length of 760 mm.

  The external electrodes 13a and 13b are formed by, for example, attaching an aluminum tape having a width of 1 mm over the entire length of the light source lamp 10 to an opposing position across the lamp central axis on the outer surface of the arc tube 11. Yes. The external electrodes 13a and 13b may be formed by screen printing and baking a conductive paste, for example. Specifically, the external electrode can be formed by firing a conductive paste containing silver. On the outer peripheral surfaces of the external electrodes 13a and 13b, an insulating layer 14 made of a translucent ceramic film is formed for the purpose of protecting the external electrodes 13a and 13b. Further, one end of each of the external electrodes 13a and 13b is connected to a lighting power source outside the device (not shown) via lead wires 15a and 15b.

  As the rare gas sealed in the arc tube 11, for example, xenon gas or a mixed gas of xenon and other rare gas can be exemplified, and the sealed amount is, for example, 17 kPa. In the rare gas discharge lamp 2, since the enclosed xenon gas or the like becomes a luminescent species and emits light by discharge, no harmful substances such as mercury are used, and a lamp with low environmental load can be provided. There are advantages such as.

  In the present embodiment, when the noble gas discharge lamp 2 shown in FIG. 2 is arranged in the backlight device 1 shown in FIG. 1, as shown in FIG. The direction at is reversed. FIG. 3A is a schematic view seen from the opening side of the backlight device when eight rare gas discharge lamps 2 are arranged in parallel. The rare gas discharge lamps 2 are arranged in the order of 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2h from the top. In this drawing, the easily startable part 16 provided in the rare gas discharge lamp 2a is arranged on the left side, and the rare gas discharge lamp 2b adjacent to the rare gas discharge lamp 2a is the easily startable part. The position where 16 is provided is on the right side of the figure. Further, in the rare gas discharge lamp 2c adjacent to the rare gas discharge lamp 2b, the easily startable portion 16 is provided on the left side. Thus, for each adjacent rare gas discharge lamp 2, the position where the easily startable portion 16 is provided is reversed in the lamp axis direction of the rare gas discharge lamp 2. In addition, FIG. 6 schematically shows a state in which the discharge plasma 32 is growing in the direction of the arrow starting from the easily startable portion 16. The discharge plasma 32 repeats lighting and blinking according to the frequency of the high-frequency voltage applied to the rare gas discharge lamp 2 that is turned on at a high frequency. Each time this lighting and blinking is performed, the light emission starts from the easily startable portion 16. It extends to the entire tube 11. Such flickering of light and bias in the amount of light caused by the discharge plasma 32 that spreads every time the light is turned on and off can be improved by inverting the easy-startability portion 16 as shown in FIG.

  FIG. 3-b) shows another example in which the easily startable portion 16 is reversely arranged. This figure is a schematic view as seen from the opening side of the backlight device when eight rare gas discharge lamps 2 are arranged in parallel as in FIG. The rare gas discharge lamps 2 are arranged in the order of 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2h from the top. In the figure, the two easily startable portions 16 of the lamps of the rare gas discharge lamps 2a and 2b are both arranged on the left side. Next, the easily startable portions 16 of the two lamps of the rare gas discharge lamps 2c and 2d are both arranged on the right side. Further, the easily startable portions 16 of the two lamps of the rare gas discharge lamps 2e and 2f are both arranged on the left side. As described above, the position of the easily startable portion 16 is reversed and arranged on the lamp axis in the left and right directions for each lamp group including two lamps. FIG. 3B also schematically shows a state where the discharge plasma 32 is growing in the direction of the arrow starting from the easily startable portion 16. The discharge plasma 32 repeats lighting and blinking according to the frequency of the high-frequency voltage applied to the rare gas discharge lamp 2 that is turned on at a high frequency. Each time this lighting and blinking is performed, the light emission starts from the easily startable portion 16. It extends to the entire tube 11. The flickering of light and the bias in the amount of light caused by the discharge plasma 32 spreading every time such lighting and blinking are performed by inverting the easily startable portion 16 for each of a plurality of lamp groups as shown in FIG. But it will be improved.

  FIG. 3-c) shows another example in which the easily startable portion 16 is reversely arranged. This figure is a schematic view seen from the opening side of the backlight device when eight noble gas discharge lamps 2 are arranged in parallel, as in FIGS. 3A and 3B. The rare gas discharge lamps 2 are arranged in the order of 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2h from the top. In the figure, the two easily startable portions 16 of the lamps of the rare gas discharge lamps 2a and 2b are both arranged on the left side. Next, in the rare gas discharge lamp 2c, the easy family member 16 is disposed on the right side. Further, in the rare gas discharge lamp 2d adjacent to the rare gas discharge lamp 2c, the easily startable portion 16 is disposed on the left side. Further, in the rare gas discharge lamp 2e adjacent to the rare gas discharge lamp 2d, the easily startable portion 16 is disposed on the right side. The easily startable portions 16 of the two rare gas discharge lamps 2f and 2g adjacent to the rare gas discharge lamp 2e are arranged on the left side. Further, the easily startable portion 16 of the rare gas discharge lamp 2h is arranged on the right side. As described above, the position of the easily startable portion 16 is such that a lamp group consisting of two lamps or one of the rare gas discharge lamps is irregularly inverted from side to side on the lamp axis. In other words, the easy-startable portion 16 may be disposed so as to be generally distributed to the left and right as the entire backlight device, and is reversed for each lamp or for each lamp group having a certain number. There is no need. Further, in a) and b) of this embodiment, the number of lamps arranged on the left side and the number of lamps arranged on the right side are the same number, but as shown in c), the number of lamps arranged on the right side is substantially left and right. It is only necessary that they are arranged in a distributed manner, and they do not necessarily have to be the same number on the left and right. These are appropriately set according to the number of the rare gas discharge lamps arranged as the entire backlight device, the arrangement of transformers connected to the rare gas discharge lamps, and the like.

  FIG. 3C schematically shows a state in which the discharge plasma 32 is growing in the direction of the arrow from the easily startable portion 16 as a starting point. The discharge plasma 32 repeats lighting and blinking according to the frequency of the high-frequency voltage applied to the rare gas discharge lamp 2 that is turned on at a high frequency. Each time this lighting and blinking is performed, the light emission starts from the easily startable portion 16. It extends to the entire tube 11. As shown in FIG. 3C, the flickering of light and the deviation of the light amount caused by the discharge plasma 32 that spreads every time when the light is turned on and blinking, the position of the easily startable portion 16 is substantially dispersed from side to side on the lamp axis. It is improved by being arranged.

  As a second embodiment of the present invention, a schematic view of the backlight device 50 is shown in FIG. FIG. 4A shows a lamp group 53 in which a plurality of transformers 51 are provided in the casing 52 of the backlight device 50, and a plurality of the rare gas discharge lamps 2 are connected to each of the transformers 51. FIG. 5 is a diagram in which the positions on the lamp axis where the easily startable portions 16 are arranged are reversed for each lamp group 53. Specifically, one transformer 51 is provided for the lamp group 53 including the two rare gas discharge lamps 2, and is connected via the power supply line 15. The easily startable portion 16 is disposed at a position opposite to the direction on the lamp axis from the side where the transformer 51 is disposed. That is, the noble gas discharge lamp 2 is provided with the easily startable portion 16 at one end in the direction on the lamp axis, and the power supply line 15 connected to the transformer 51 at the other end. ing. Further, for each lamp group 53, the direction on the lamp axis where the easily startable portion 16 is arranged is reversed.

  FIG. 4B schematically shows how the discharge plasma 32 spreads from the easily startable portion 16 of the rare gas discharge lamp 2 in the backlight device 50. In this figure, the state immediately after starting the rare gas discharge lamp 2 is shown, and the discharge plasma 32 generated from the easily startable portion 16 is gradually growing in the direction indicated by the arrow. Is shown. The discharge plasma 32 gradually grows in the direction of the arrow and spreads to the entire arc tube of the rare gas discharge lamp 2. Here, the rare gas discharge lamp 2 is characterized in that, by applying a high-frequency voltage, the light is repeatedly turned on and off whenever the applied polarity of the high-frequency voltage changes. That is, the noble gas discharge lamp 2 is repeatedly turned on and off in accordance with the frequency of the applied high frequency, and each time an arrow in the figure of the discharge plasma 32 starting from the easily startable portion 16 is obtained. Growth in the direction is repeated. Further, the backlight device 50 as a whole may be used in a dimming mode by making it variable, for example, by reducing the amount of light emitted from the rare gas discharge lamp 2. In such a case, the rare gas discharge lamp 2 is used by burst lighting. This adjusts the width of the OFF time of the rare gas discharge lamp 2 corresponding to the low-frequency ON-OFF signal, and the high-frequency voltage is applied during the ON time, and lighting and blinking are repeated. In the case of lighting in this dimming mode, the rare gas discharge lamp 2 is not lit during the OFF time, and the discharge plasma 32 is directed in the axial direction from the easily startable portion 16 when the ON time starts. grow up. In this case, since there is a low-frequency extinguishing time, the fluctuation in the amount of light during the growth of the discharge plasma 32 is more emphasized. Therefore, as shown in the figure, for each lamp group 53 in which the direction in which the easily startable part 16 is provided is the same, the positions of the easily startable parts 16 are distributed to the left and right on the drawing. As a whole, the backlight device 50 can suppress flickering.

  Further, by adopting such a configuration, the number of the transformers 51 to be arranged can be reduced, and the backlight device 50 as a whole can be reduced in weight and size. In addition, since the easily startable portion 16 and the power supply line 15 connected to the transformer 51 are provided on different end sides in the direction on the lamp axis of the rare gas discharge lamp 2, the rare gas There is also an effect that the power loss generated in the easily startable portion 16 is reduced when the discharge lamp 2 is turned on. Furthermore, the flicker can be reduced as the entire backlight device 50.

  A third embodiment of the present invention is shown in FIG. FIG. 5A shows that the position of the easily startable portion 16 of the rare gas discharge lamp 2 arranged in parallel in the casing 62 of the backlight device 60 is reversed for each rare gas discharge lamp 2. ing. In the present embodiment, the position of the easily startable portion 16 is arranged in the same direction in a lamp group 63 in which two rare gas discharge lamps 2 are connected to one transformer 61. However, the rare gas discharge lamps 2 belonging to the other lamp group 64 are arranged between the two rare gas discharge lamps 2, and as a result, the position of the easily startable portion 16 for each rare gas discharge lamp 2. Are arranged in reverse.

  FIG. 5B schematically shows how the discharge plasma 32 spreads from the easily startable portion 16 of the rare gas discharge lamp 2 in the backlight device 60 as in the case of FIG. For each lamp group 63 having the same direction in which the easily startable portion 16 is provided, the discharge plasma 32 spreads in the direction of the arrow in a distributed manner on the left and right of the drawing, and finally spreads over the whole. The phenomenon in which the discharge plasma 32 spreads occurs in conjunction with the ON / OFF cycle of the inverter, which is the lighting frequency. Since the direction in which the discharge plasma 32 spreads is reversed for each of the rare gas discharge lamps 2 disposed in the casing 62, flickering can be suppressed as a whole of the backlight device 60. Furthermore, as a dimming mode, the flickering can be suppressed and the fluctuation of the light amount on the entire screen can be suppressed even if the entire light amount is reduced by increasing the inverter OFF time and the OFF cycle interval. There is. In the present embodiment, the case where two rare gas discharge lamps are connected to one lamp group 63 is shown, but the transformer 61 is arranged corresponding to each rare gas discharge lamp 2. May be.

The disassembled perspective view which shows the structure of the backlight apparatus in the 1st Example of this invention. The figure which shows the structure of the noble gas discharge lamp as described in the 1st Example of this invention. Explanatory drawing which showed arrangement | positioning of the noble gas discharge lamp in 1st Example of this invention. Explanatory drawing which showed arrangement | positioning of the noble gas discharge lamp in the 2nd Example of this invention. Explanatory drawing which showed arrangement | positioning of the noble gas discharge lamp in the 3rd Example of this invention. Schematic which shows the conventional backlight apparatus. Explanatory drawing which shows arrangement | positioning of the backlight apparatus which uses a noble gas discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Backlight apparatus 2 Noble gas discharge lamp 10 Light source lamp 11 Arc tube 12 Phosphor layer 13a, 13b External electrode 14 Insulating layer 15 Feed line 15a, 15b Lead wire 16 Easy startability part 20 Backlight apparatus 21 Case 21A Opening part 22 Reflective sheet 40 Sheet body 41 Diffusion plate 42 Diffusion sheet 43 Directivity control sheet 50 Backlight device 51 Transformer 52 Housing 53 Lamp group 60 Backlight device 61 Transformer 62 Housing 63 Lamp group 64 Other lamp group 70 Backlight device 71 High-frequency transformer 32, 72 Discharge plasma 80 Light source lamp 81 Cold cathode type low-pressure mercury lamp

Claims (3)

A housing having an opening for emitting light and having a reflector disposed therein;
A plurality of light source lamps arranged parallel to and spaced from each other inside the housing;
A sheet body having a light correction function disposed so as to cover the opening of the housing;
A backlight device comprising:
The light source lamp is:
A straight tubular arc tube with a rare gas sealed inside,
A phosphor layer formed on the inner surface of the arc tube;
A pair of external electrodes arranged to extend in the tube axis direction on the outer surface of the arc tube;
An easily startable part formed on the inner peripheral surface in the vicinity of one end of the arc tube;
Comprising a noble gas discharge lamp comprising
A backlight device characterized in that when a plurality of the rare gas discharge lamps are arranged in parallel, the direction on the lamp axis where the easily startable portion is arranged is reversed in the casing.   The casing is provided with a plurality of transformers for supplying power to a power supply unit provided at one end of the rare gas discharge lamp, and a single lamp group is formed by a plurality of rare gas discharge lamps connected to the transformer. The position of the easily startable part of the rare gas discharge lamp in the lamp group is the end opposite to the side connected to the transformer, and the easily startable part is set for each adjacent lamp group. The backlight device according to claim 1, wherein the direction on the lamp axis where the sex part is arranged is reversed.   The plurality of rare gas discharge lamps arranged in the housing are arranged in parallel to each other, and an easily startable portion is provided at one end in the lamp tube axial direction, and each of the adjacent rare gas discharge lamps is adjacent to each other. 2. The backlight device according to claim 1, wherein the direction on the lamp axis where the easily startable portion is disposed is reversed.

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