JP2007095559A - Light emitting device and liquid crystal display using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device having no luminous gradient and with uniform luminance. <P>SOLUTION: The light emitting device 150 comprises a plurality of light emitting light sources 100, and the light source 100 includes an airtight arc tube 10, a discharge medium which is sealed inside the arc tube 10 and is made mainly of a rare gas, and a first electrode 11 and a second electrode 12 for exciting the discharge medium. The first electrode 11 is arranged at one end of the arc tube 10 and the second electrode 12 is arranged at the other end of the arc tube 10. The light source 100 has a luminance gradient including a high luminance region and a low luminance region between the first electrode 11 and the second electrode 12. The plurality of light sources 100 are arranged mutually adjacent to each other, and the high luminance region of one of the adjoining light sources 100 and the low luminance region of the other light source 100 are arranged alternately so as to be opposed to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device comprising an arc tube having airtightness, a discharge medium mainly composed of a rare gas enclosed in the arc tube, and at least a first electrode and a second electrode for exciting the discharge medium. And a liquid crystal display device using the same.

  As a conventional fluorescent lamp and a liquid crystal display device using the same, an internal electrode is provided inside one end of an arc tube (hereinafter referred to as a lamp tube main body in the description of the background art), and an external electrode is provided on the outer surface of the other end. A discharge gas sealed inside the lamp tube by forming an electrode and applying an alternating voltage between the internal electrode and the external electrode from a lighting circuit arranged between the internal electrode and the external electrode Similarly, there has been proposed a method of generating light by exciting a fluorescent material layer formed inside a lamp tube (see, for example, Patent Document 1).

  FIG. 23 is a cross-sectional view showing a conventional fluorescent lamp described in Patent Document 1 and a liquid crystal display device using the same. 23, a cold cathode ray tube lamp 700 has a cylindrical lamp tube main body 701 closed at both ends, a discharge gas 702 sealed inside the lamp tube main body 701, and a fluorescence formed on the inner wall of the lamp tube main body 701. The material layer 703, the first electrode 704 formed on the outer surface of the end portion of the lamp tube main body 701, and the second electrode 705 formed inside the end portion of the lamp tube main body 701 opposite to the first electrode 704. It is configured.

  Connected to the first electrode 704 and the second electrode 705 is a power application device 707 that receives low-voltage direct current from the power supply device 706 and converts it to high-voltage alternating current. The power application device 707 includes an inverter and a transformer (both not shown).

  Here, AC power output at several kV from the output terminal 708 of the power application device 707 is supplied to the cold cathode ray tube lamp 700. At this time, AC power is supplied to the first electrode 704 after being output from the output end 708 of the power application device 707. By such an operation, the cold cathode ray tube lamp 700 is driven, the fluorescent material layer 703 is excited by the discharge gas 702, and the cold cathode ray tube lamp 700 emits light.

  On the other hand, FIG. 24 shows an example in which a plurality of the conventional cold cathode ray tube lamps 700 are juxtaposed. In FIG. 24, the same parts as those in FIG. 23 may be denoted by the same reference numerals, and redundant description may be omitted. In FIG. 24, a plurality of cold cathode ray tube type lamps 700 are simultaneously connected in parallel to one power application device 707. Thereby, even if the current characteristics are different among the respective cold cathode ray tube type lamps 700, the luminance of each cold cathode ray tube type lamp 700 can be made uniform.

The reason why the luminance can be made uniform is that the first electrode 704 is formed on the outer surface of the lamp tube main body 701, and the portion covered with the first electrode 704 has a role of a dielectric, and the first electrode 704 This is because the lamp tube main body 701 and the plasma inside the lamp tube main body 701 have a kind of capacitance role. That is, when the lamp tube body 701 that is a dielectric is inserted between the discharge space where the plasma is formed and the first electrode 704 to form a capacitance impedance, the ion and electron concentrations in the discharge space are specified. The higher the concentration, the more conversely the current flow is disturbed by the capacitive impedance. For this reason, even if a plurality of cold cathode ray tube lamps 700 are driven in parallel by one power application device 707, the cold cathode ray tube lamp 700 having an excellent current flow obstructs the current flow and the current flow is reduced. An unsatisfactory cold cathode ray tube type lamp 700 promotes the flow of current, and as a result, the luminance variation of each cold cathode ray tube type lamp 700 is corrected to cause uniform light emission.
JP 2003-168397 A

  However, in the above-described conventional configuration, the luminance variation for each lamp (in the conventional example, the cold cathode ray tube type lamp 700) can be corrected for the above-mentioned reason. However, the luminance unevenness or the luminance gradient in the tube axis (lamp longitudinal) direction of each lamp. Cannot be corrected. The reason will be described below.

  Recently, liquid crystal display devices (particularly liquid crystal televisions) have become larger. For example, in the case of a 32 inch diagonal liquid crystal television, a cold cathode lamp having a length of about 730 mm and a length of about 1000 mm for a 45 inch are used. A plurality of cold cathode lamps are incorporated. For this reason, in the conventional configuration, the luminance gradient in the lamp tube axis direction is further increased with respect to the lengthening of the lamp, and a countermeasure for suppressing the luminance gradient is required.

  When the lamp is driven by applying a high voltage from one side of the lamp, the luminance gradient increases the leakage current on the high-voltage side due to the influence of a nearby conductor (for example, a reflector or a housing) in the vicinity of the lamp. The tube wall temperature distribution and the luminance distribution in the tube axis direction (longitudinal direction) have an inclination, which causes a luminance inclination.

  The cause of this luminance gradient will be described in a little more detail. 25 (a) and 25 (b) show an internal electrode 801 disposed inside one end of the arc tube 800, an external electrode 802 and an internal electrode 801 similarly disposed outside the other end of the arc tube 800. It is a schematic diagram of a fluorescent lamp 900 composed of a lighting circuit 803 that applies a voltage between the external electrode 802 and the same configuration as the cold cathode ray tube lamp of the conventional example.

  The arc tube 800 is a glass hermetic container, in which a discharge medium made of a rare gas or mercury and a light emitting layer that emits visible light by excitation of the discharge medium are formed. In order to simplify the explanation, the description and explanation in the drawings are omitted.

  A plurality of charges (marked with (−) in the figure) from the internal electrode 801 toward the external electrode 802 are first accumulated on the inner wall of the arc tube 800 on the external electrode 802 side. Subsequently, when the amount of charge in the direction of the external electrode 802 exceeds the capacitance determined from the external electrode 802 and the arc tube 800, the surplus charge is uniformly distributed on the tube wall away from the external electrode 802. Accumulated. As a result, the current density is high on the internal electrode 801 side and low on the external electrode 802 side, resulting in a luminance gradient (see FIG. 25A).

  On the other hand, when the capacitance determined from the external electrode 802 and the arc tube 800 is large, all electric charges directed toward the external electrode 802 are accumulated on the inner wall of the arc tube 800 on the external electrode 802 side. At that time, no surplus charge is generated, and the current density is equal between the internal electrode 801 side and the external electrode 802 side, so that no luminance gradient occurs (see FIG. 25B).

  We measured the luminance gradient in the direction of the lamp tube axis by doubling the length of the above-mentioned conventional fluorescent lamp. FIG. 26 shows the result. In FIG. 26, the length of the lamp is 880 mm, the diameter of the lamp is 3 mm, and the length of the external electrode in the tube axis direction is 10 mm.

  As can be seen from FIG. 26, the luminance gradient in the lamp tube axis direction, which was not a big problem with the lamp length (for example, 378 mm) in the conventional configuration, when the lamp is made longer, for example, at 880 mm, the lamp The luminance gradient in the tube axis direction is about 30% (when the luminance on the internal electrode side is set to 100%, it decreases to about 70% on the external electrode side), which is directly reflected in the luminance unevenness of the fluorescent lamp. Is incorporated into a liquid crystal display device, it causes uneven brightness on the screen, which is a problem that cannot be ignored.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and in the arrangement of a plurality of light emitting light sources, a light emitting device in which luminance unevenness is eliminated by arranging the luminance gradients to cancel each other, and a liquid crystal display device using the same I will provide a.

  The light-emitting device of the present invention is a light-emitting device including a plurality of light-emitting light sources, and the light-emitting light source is a discharge medium mainly composed of an air-tight arc tube and a rare gas sealed inside the arc tube. A light emitting layer excited and emitted by the discharge medium, a first electrode and a second electrode for exciting the discharge medium, the first electrode being disposed at one end of the arc tube, The second electrode is disposed at the other end of the arc tube, and the light emitting light source has a luminance gradient including a high luminance region and a low luminance region between the first electrode and the second electrode. The plurality of light emitting sources are arranged adjacent to each other, and are alternately arranged so that the high luminance region of one adjacent light emitting source and the low luminance region of the other light emitting source are opposed to each other. It is characterized by that.

  The liquid crystal display device of the present invention includes the light emitting device of the present invention, a reflecting member that reflects light emitted from the light emitting device to the liquid crystal panel side, and condenses light from the light emitting device and the reflecting member. A light collecting member, a liquid crystal panel that transmits light from the light collecting member, and a housing that holds and fixes the light emitting device, the reflecting member, the light collecting member, and the liquid crystal panel. To do.

  According to the light-emitting device of the present invention, it is possible to provide a light-emitting device with no luminance gradient and uniform luminance.

  Further, according to the liquid crystal display device of the present invention, since the light emitting device of the present invention is provided, a liquid crystal display device with uniform luminance distribution and no luminance unevenness can be provided.

  The light-emitting device of the present invention includes a plurality of light-emitting light sources, and the light-emitting light sources are an air-tight arc tube, a discharge medium mainly composed of a rare gas enclosed in the arc tube, and excitation light emission by the discharge medium. And a first electrode and a second electrode for exciting the discharge medium. In addition, the first electrode is disposed at one end of the arc tube, the second electrode is disposed at the other end of the arc tube, and the light emitting light source is a high luminance region between the first electrode and the second electrode. And a low-luminance region. Further, the plurality of light emitting sources are arranged adjacent to each other, and are alternately arranged so that the high luminance region of one adjacent light emitting light source and the low luminance region of the other light emitting source are opposed to each other. Yes. By alternately arranging the high-intensity area of one adjacent light-emitting light source and the low-intensity area of the other light-emitting light source to face each other, the adjacent light-emitting light sources complement each other in luminance gradient, and the entire light-emitting device As a result, the luminance can be made uniform.

  In addition, the arc tube is formed from a long narrow tube, the first electrode is disposed inside one end of the arc tube, the second electrode is disposed outside the other end of the arc tube, The first electrodes of one of the adjacent light emitting sources and the second electrode of the other emitting light source may be alternately arranged so as to face each other. Also by this, adjacent light emitting sources complement each other with the luminance gradient, and the luminance of the entire light emitting device can be made uniform.

  In addition, it is preferable that the second electrode and the arc tube are arranged at a predetermined distance or more with a gap therebetween. Thereby, the dielectric breakdown between the second electrode and the arc tube can be prevented.

  Moreover, it is preferable that the said space | gap is narrowly arrange | positioned at the outermost part of the said arc_tube | light_emitting_tube, and is widened toward the said 1st electrode side. Thereby, the inclination of the tube surface brightness | luminance of an arc_tube | light_emitting_tube can be relieve | moderated.

  Further, it is preferable that the length L1 of the arc tube and the length L2 of the second electrode satisfy a relationship of 0 <L2 / L1 ≦ 0.2. Thereby, the inclination of the tube surface luminance of the arc tube can be reduced.

  More preferably, the length L1 of the arc tube and the length L2 of the second electrode satisfy a relationship of 0.01 <L2 / L1 ≦ 0.1. Thereby, the inclination of the tube surface brightness of the arc tube can be further reduced.

  Further, the discharge medium can contain at least mercury.

  Further, it is preferable that the surface of the second electrode facing the arc tube is subjected to a diffuse reflection treatment for visible light. Further, it is preferable that the back surface of the second electrode on the side facing the arc tube is subjected to a diffuse reflection treatment for visible light. Thereby, the uniformity of the luminance of the light emitting device can be further improved.

  The second electrode is preferably capable of holding the arc tube. By providing the second electrode with a function of holding the arc tube, other holding members can be reduced.

  In addition, a lighting circuit capable of applying a voltage between the first electrode and the second electrode can be further included.

  The liquid crystal display device of the present invention includes the light emitting device of the present invention, a reflecting member that reflects light emitted from the light emitting device to the liquid crystal panel side, a light collecting member that collects light from the light emitting device and the reflecting member, The liquid crystal panel which permeate | transmits the light from a condensing member, and the housing | casing which hold | maintains and fixes a light-emitting device, a reflection member, a condensing member, and a liquid crystal panel are provided. Thereby, it is possible to provide a liquid crystal display device having no luminance unevenness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts may be denoted by the same reference numerals and redundant description may be omitted.

  Further, when various conditions in the second and subsequent embodiments are the same as those in the first embodiment, the description thereof may be omitted.

(Embodiment 1)
FIG. 1 is a perspective view of a light emitting light source 100 according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view in a plane including the lines AA and BB in FIG.

  1 and 2, a light emitting light source 100 includes an elongated tubular light emitting tube 10, a cup-shaped first electrode 11 disposed inside one end of the light emitting tube 10, and the outside of the other end of the light emitting tube 10. And a second electrode 12 arranged at a predetermined distance or more through a gap.

  Between the arc tube 10 and the second electrode 12, two supports 13 made of silicone resin having the shape shown in FIG. 3 are inserted, and the support 13 is a substantially U-shaped inner wall surface of the second electrode 12. The arc tube 10 and the second electrode 12 are held and fixed at a predetermined distance from each other.

  In this embodiment, the support 13 is fixed to the second electrode 12 by pressing. However, in order to fix the support 13 more firmly, for example, a convex portion (not shown) is provided on the side surface of the support 13, What is necessary is just to provide the opening part (not shown) of the magnitude | size which a convex part enters in the position which fits with the convex part of the said support 13 by the side of the 2 electrode 12, and to insert and engage both.

  In addition to the above, there are methods such as adhesion, melting, and integral molding, but detailed description thereof is omitted here.

  A lead wire 14 is connected to the first electrode 11, and a lead wire 15 is connected to the second electrode 12.

  As the arc tube 10, a so-called long and narrow tube whose cross-sectional shape perpendicular to the tube axis (longitudinal) direction of the arc tube 10 is generally circular or substantially circular is used. This is because the tubular type is distributed in the largest quantity and at a low cost as a standard type. However, the shape of the arc tube 10 in the present embodiment is not limited to the tubular type, and the cross-sectional shape may be an irregular shape such as an ellipse, a triangle, or a quadrangle. Moreover, it does not need to be elongate.

  The arc tube 10 is basically formed of a translucent material, and borosilicate glass is used in this embodiment. The arc tube 10 may be made of glass such as quartz glass, soda glass, lead glass, or an organic material such as acrylic resin instead of borosilicate glass.

  The specification of the glass tube used for the arc tube 10 was a length of 730 mm, an outer diameter of 4 mm, and an inner diameter of 3 mm in this embodiment. The length, outer diameter, inner diameter and the like of the arc tube 10 are not limited to the above, and may be adjusted to the required specifications of the light emitting light source 100, and the outer diameter is usually about 1.0 mm to 10 mm. For example, it may be about 30 mm used in general illumination fluorescent lamps. Further, the distance between the outer surface and the inner surface of the glass tube, that is, the thickness of the glass tube is usually about 0.1 mm to 1.0 mm.

  Note that the arc tube 10 is not limited to a linear shape, and may have other shapes. For example, an irregular shape such as an L shape, a U shape, or a rectangular shape may be used. Further, when the arc tube 10 having these shapes is used as, for example, a backlight of a liquid crystal display device described later, a plurality of arc tubes 10 can be arranged on the same plane, and the arc tube 10 is L-shaped. Alternatively, in the case of a rectangular shape, the L-shaped or rectangular arc tube 10 can be juxtaposed on both sides of the end portion of the light guide plate.

  Both ends of the arc tube 10 are sealed, and the discharge medium 16 is sealed inside thereof (the same applies to cases other than the first embodiment). In this embodiment, about 8 kPa of a mixed gas of neon (95%) and argon (5%) and about 3 mg of mercury were sealed.

  When the material of the arc tube 10 is made of quartz glass, the ultraviolet light excited and emitted by the enclosed mercury is directly irradiated to the outside of the arc tube 10 and thus can be used as a light source for ultraviolet cleaning or ultraviolet curing.

As shown in FIG. 2, a phosphor layer 17 is formed on the inner wall surface of the arc tube 10. The phosphor layer 17 is formed to convert the wavelength of light emitted from the discharge medium 16, and in this embodiment, red (Y ₂ O ₃ : Eu ³⁺ ), green (LaPO ₄ : Ce). ³⁺ , Tb ³⁺ ) and blue (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) were used in combination.

  By changing the material of the phosphor layer 17, light of various wavelengths can be obtained. For example, white light or red, green, and blue light can be obtained. The phosphor layer 17 can be formed of a material used for so-called general illumination fluorescent lamps, plasma displays, and the like.

  The first electrode 11 is formed inside one end of the arc tube 10. The first electrode 11 is a niobium cup electrode in this embodiment. Besides this material, for example, a metal such as tungsten or nickel can be used.

  The first electrode 11 has a cup shape, but the shape is not particularly limited, and may be a rod shape or a plate shape.

  The first electrode 11 may be partially or entirely covered with a metal oxide layer such as cesium oxide, barium oxide, or strontium oxide. By using such a metal oxide layer, an increase in lighting start voltage can be suppressed, and electrode deterioration due to ion bombardment can be prevented. The surface of the first electrode 11 may be covered with a dielectric layer (for example, a glass layer).

  In the present embodiment, as shown in FIG. 4, the second electrode 12 is made of aluminum having a substantially U-shaped cross section, and has an inner surface and an outer surface having specular reflection characteristics. In addition to the above materials, a metal such as copper or stainless steel, a transparent conductor mainly composed of tin oxide, indium oxide, or the like can be used. In addition, the lead wire 15 is fixed to the lower part (bottom surface) of the second electrode 12 by caulking so that the second electrode 12 and the lead wire 15 are in an electrically conductive state.

  One side of the substantially U shape of the second electrode 12 is about 5 mm, for example, and there are three sides. The length of the second electrode 12 is set to about 50 mm, for example, and covers the arc tube 10. Here, the reason why the length of the second electrode 12 is set to, for example, 50 mm is as follows.

FIG. 5 shows the relationship of the tube surface brightness of the arc tube 10 with respect to the length of the second electrode 12.
In FIG. 5, it can be seen that the inclination of the tube surface brightness of the arc tube 10 decreases as the length of the second electrode 12 is shorter.

  Here, assuming that the length of the arc tube 10 is L1 and the length of the second electrode 12 is L2, the relationship between the two can be set in a range of 0 <L2 / L1 ≦ 0.2 from the result of FIG. The influence of the brightness gradient can be reduced. Specifically, when the length L1 of the arc tube 10 is set to 730 mm, for example, the length L2 of the second electrode 12 is preferably 146 mm or less from the above relational expression.

  However, with this length, in the evaluation of the luminance uniformity of a liquid crystal display device (an example in which a plurality of light emitting light sources 100 are juxtaposed), which will be described later, the long side length (corresponding to the length L1 of the arc tube 10) ), The luminance at the inner side is measured about 1/10, so that the influence of the luminance gradient is still large at the position of 146 mm.

  Therefore, assuming the actual state of the liquid crystal display device, if the length L1 of the arc tube 10 is 730 mm, for example, the relationship between the length L1 of the arc tube 10 and the length L2 of the second electrode 12 is 0.01 <. A more preferable length is set in the range of L2 / L1 ≦ 0.1. Specifically, when the length L1 of the arc tube 10 is set to, for example, 730 mm, the length L2 of the second electrode 12 is preferably 73 mm or less from the above relational expression.

  From the above results, the length of the second electrode 12 in the first embodiment is set to 50 mm, for example, in consideration of variations in the length.

  The cross-sectional shape of the second electrode 12 is not limited to a substantially U shape, and may be a semicircular shape or a polygonal shape.

  In the light emitting light source 100, a discharge is generated by applying a voltage by the lighting circuit 18 between the first electrode 11 and the second electrode 12, and the discharge medium 16 is excited. The excited discharge medium 16 emits ultraviolet rays (not shown) when transitioning to the ground state. This ultraviolet light is converted into visible light (not shown) by the phosphor layer 17 and emitted from the arc tube 10.

  Next, the gap between the second electrode 12 and the arc tube 10 of this embodiment will be described. As shown in FIG.1 and FIG.2, in this embodiment, the 2nd electrode 12 and the arc_tube | light_emitting_tube 10 are arrange | positioned apart from the predetermined distance via the space | gap, without closely_contact | adhering.

  The distance between the second electrode 12 and the arc tube 10 may not be the same with respect to the tube axis direction (agreeing with the “longitudinal direction”). Furthermore, the distance between the second electrode 12 and the arc tube 10 may not be the same in the direction perpendicular to the tube axis direction of the second electrode 12, that is, the tube circumferential direction of the arc tube 10.

  For example, if the gap between the arc tube 10 and the second electrode 12 is arranged to be narrow at the extreme end of the arc tube 10 and become wider toward the first electrode 11 side, the light emission at the length L2 of the second electrode 12 The inclination of the tube surface brightness of the tube 10 can be reduced.

  In any case, the second electrode 12 and the arc tube 10 are not in close contact with each other, and the shortest distance between the second electrode 12 and the arc tube 10 is separated by a predetermined distance or more via a gap. What is necessary is just to arrange.

  Further, although the support 13 is used as a means for separating the distance between the second electrode 12 and the arc tube 10, there can be various means using an insulating member other than this. Since any means can be easily realized, a description with a specific example is omitted.

  Conventionally, the second electrode 12 that is an external electrode and the arc tube 10 are generally formed so that there is no gap by pressing or bonding, that is, the second electrode 12 and the arc tube 10 are in close contact with each other. Done. However, due to manufacturing errors of the light emitting light source 100, vibrations during operation, environmental coldness, and the like, the contact state between the second electrode 12 as the external electrode and the arc tube 10 is likely to be unstable, and a minute gap is formed. It was easy to occur. As a result, the air between the minute gaps is ionized to generate ozone (details of the ozone generation mechanism will be described later), and furthermore, the power cannot be normally input to the arc tube 10, so that the emission intensity of the light source 100 is emitted. May become unstable.

  In particular, the difference in emission intensity of the light source 100 may be very large between the case where the second electrode 12 which is an external electrode and the arc tube 10 are partly touched and the case where they are not touched at all. It was.

  That is, since the distance between the outer surface of the arc tube 10 and the second electrode 12 that is an external electrode is very important for controlling the light emission intensity of the light source 100, the conventional method is based on the premise that the two are in close contact with each other. In the method, slight positional misalignment and generation of ozone in the boundary region between the external electrode and the arc tube led to deterioration of the emission characteristics.

  On the other hand, in the present embodiment, since both are arranged at a large distance, even if the same positional shift amount occurs, the change rate amount is significantly small, so that the light emission characteristics of the light source 100 are hardly affected. That is, in the present embodiment, the second electrode 12 and the arc tube 10 are in a state of being reliably separated from each other, and the light emission of each part of the light emission source 100 can be sufficiently stabilized.

  In the present embodiment, air, which is the most common atmosphere, is assumed for the gap between the second electrode 12 and the arc tube 10, but it is not limited to the case of air. It may be a rare gas such as neon, krypton, xenon, or nitrogen. Furthermore, it is sufficient if dielectric breakdown does not occur even in a reduced pressure state. That is, it is possible to enclose a gas that is transparent and does not easily break down in the gap between the second electrode 12 and the arc tube 10.

  In order to fill the gap with a gas other than air, it is necessary to have a double tube structure in which the arc tube 10 and the second electrode 12 are arranged on the inner side. Can be easily implemented.

  Next, the relationship between the shortest distance between the arc tube 10 and the second electrode 12 that is an external electrode and the ozone generated in the gap will be described.

  In conventional light-emitting light sources, the adhesion between the external electrode and the arc tube tends to be unstable, and dielectric breakdown occurs in the gaps in areas where the adhesion is uncertain, resulting in ozone, which emits light. There has been a problem of destroying the light source and each member constituting the periphery thereof.

  In the present embodiment, the shortest distance between the second electrode 12 which is an external electrode and the arc tube 10 is separated by a predetermined distance or more, in other words, between the second electrode 12 and the arc tube 10 so as not to cause dielectric breakdown. The said subject is solved by the means of arrange | positioning through a space | gap.

  Specifically, the shortest distance between the arc tube 10 and the second electrode 12 is desirably 0.1 mm or more and 2.0 mm or less. The lower limit of the shortest distance is a necessary condition for not generating ozone. On the other hand, regarding the upper limit, the maximum voltage between electrodes applied between the first electrode 11 and the second electrode 12 assumed in the present embodiment cannot be sufficiently excited in the gas inside the arc tube 10. . The above grounds will be described below.

  The distance at which the air layer existing in the gap between the second electrode 12 and the arc tube 10 is not dielectrically broken depends on various accompanying conditions. However, as a result of experiments conducted under various conditions, differences in the inner diameter (1.0 to 10 mm), gas type, gas pressure, and shape of the arc tube 10 of the arc tube 10 and the breakdown of the air layer No correlation was found.

  Moreover, the correlation of the grade which can confirm a clear difference was not recognized by the dielectric constant (3-9) of the arc_tube | light_emitting_tube 10, and the dielectric breakdown of an air layer. On the other hand, it was found that the thickness (0.1 to 1.0 mm) of the arc tube 10 and the maximum voltage between electrodes (0.1 kV to 5 kV) affect the dielectric breakdown of the air layer. In some cases, the higher the voltage is, and the thinner the arc tube 10 is, the easier the dielectric breakdown occurs in the air layer.

  Therefore, the assumed maximum voltage is about 5 kV, and the thinnest wall thickness of the arc tube 10 is about 0.1 mm. Therefore, the combination of this voltage and the wall thickness of the tubular arc tube 10 is the most severe incidental condition. It is.

  Therefore, the maximum voltage between the electrodes is set to 5 kV, the thickness of the tubular arc tube 10 is set to 0.1 mm, and other conditions are typical light emitting light sources, specifically, the inner diameter of the arc tube 10 is 2.0 mm. The relationship between the shortest distance between the arc tube 10 and the second electrode 12 that is the external electrode and the amount of ozone generated in the gap is set by setting the material of the arc tube 10 to borosilicate glass having a dielectric constant of about 5.8. The result of the examination is shown in FIG. As can be seen from FIG. 6, when the shortest distance is 100 μm (0.1 mm) or more, ozone is not generated at all (safe area). That is, it was confirmed that the amount of ozone generated was below the detection limit of the measuring device.

  As described above, the reason why the distance between the second electrode 12 and the arc tube 10 is preferably 0.1 mm or more and 2.0 mm or less under the conditions assumed in the present embodiment has been described. However, the distance between the second electrode 12 and the arc tube 10 is not limited to the above range as long as it follows the basic concept of the present embodiment.

  7 and 8 show examples of a liquid crystal display device 200 in which a plurality of light emitting light sources 100 configured as described above are adjacent to each other to form a light emitting device 150 and this light emitting device 150 is incorporated. FIG. 7 is a plan view showing the configuration of the liquid crystal display device 200, and FIG. 8 is a cross-sectional view taken along the line CC of FIG. In FIG. 8, the cross section is not hatched in consideration of the visibility of the drawing.

  7 and 8, the light source 100 is a fixed distance between the reflecting plate 19 and the light emitting light source 100 by a lamp holder 20 fixed to the reflecting plate 19 made of white resin having diffuse reflection characteristics at a plurality of locations. It is held and fixed to keep The lamp holder 20 is made of white resin and has the shape shown in FIG. 9, and is held and fixed by inserting the light emitting light source 100 into the opening in the drawing.

  The plurality of light emission sources 100 are alternately arranged so that the first electrodes 11 of one adjacent light emission source 100 and the second electrodes 12 of the other light emission source 100 face each other.

  On the upper surface of the light-emitting device 150, a resin-made diffusion plate 21 having a diffusion transmission characteristic for diffusing light emitted from the light-emitting light source 100 and the reflection plate 19, and a resin-made material for efficiently collecting the light from the diffusion plate 21 The lens sheet 22 and a resin-made polarizing sheet 23 that gives polarization to the light from the lens sheet 22 are arranged in an overlapping manner, and further, a liquid crystal panel 24 for forming and displaying an image is arranged thereon. .

  The reflection plate 19, the light emitting device 150, the diffusion plate 21, the lens sheet 22, the polarizing sheet 23, and the liquid crystal panel 24 are accommodated in a metal (aluminum) housing 25, and the liquid crystal display device 200 is configured from these.

  The luminance distribution characteristics of the liquid crystal display device 200 configured as described above are shown by solid lines and Δ marks in FIG. 10 shows a state in which the liquid crystal panel 24 is removed from the liquid crystal display device 200 (the surface of the polarizing sheet 23), and the luminance in the tube axis direction (the XX line direction in FIG. This is measured at regular intervals using a high-land color shift / luminance simultaneous multipoint measurement system “RISA-COLOR / CD7 type”).

  For comparison, the liquid crystal display device described above except that the first electrode 11 of one adjacent light emitting light source 100 and the first electrode 11 of the other light emitting light source 100 are disposed in the same direction so as to face each other. A conventional liquid crystal display device was produced in the same manner as in Example 200. The luminance distribution characteristics of the conventional liquid crystal display device configured as described above are shown by broken lines and crosses in FIG.

  From FIG. 10, it can be seen that the luminance distribution characteristics at both ends of the liquid crystal display device 200 of this embodiment are particularly improved as compared with the conventional liquid crystal display device.

  This is because the light emitting sources 100 having a luminance gradient are alternately arranged so as to be the first electrode 11 -the second electrode 12 -the first electrode 11. The brightness is equalized by complementing the slopes.

  One method for evaluating the luminance distribution characteristics of the liquid crystal display device 200 is a method shown in FIG. In FIG. 11, when the length in the long side direction of the liquid crystal display device 200 is La and the length in the short side direction is Lb, the distance of 1/10 and 1/2 of the long side length La from the short side. At the distance and the distance of 1/10 and 1/2 of the short side length Lb from the long side, the positions where the perpendiculars to the respective sides intersect (total of 9 from (1) to (9) in FIG. 11 The luminance of the portion) is measured, and the ratio (Lmin / Lmax) × 100 (%) between the minimum luminance (Lmin) and the maximum luminance (Lmax) is defined as the luminance uniformity.

  When the luminance uniformity between the liquid crystal display device 200 of the present embodiment and the conventional liquid crystal display device was determined by the above method, the results shown in Table 1 were obtained.

  As can be seen from Table 1, the light emitting light source 100 is arranged in the same direction so that the first electrode 11 of one adjacent light emitting light source 100 and the first electrode 11 of the other light emitting light source 100 face each other as in the conventional case. The luminance uniformity of the conventional liquid crystal display device when arranged is about 27%, whereas the light emission source 100 is made to be the first electrode 11 -the second electrode 12 -the first electrode 11. In addition, it can be seen that the luminance uniformity of the liquid crystal display device 200 of the present embodiment when arranged alternately is about 52%, and the luminance distribution characteristics at both ends of the liquid crystal display device 200 are particularly improved.

  In the above configuration, a liquid crystal display device having a configuration in which a diffusion sheet for further improving the diffusibility is arranged on the diffusion plate 21 or the polarizing sheet 23 is removed by making the light of the light emitting light source 100 stronger. This configuration can be selected according to each design condition.

(Embodiment 2)
In the present embodiment, an example will be described that shows that the light-emitting device and the liquid crystal display device of the present invention have still another excellent feature.

  Specifically, a description will be given of means for improving the luminance gradient in the case where even uniformity of luminance is required as compared with the first embodiment.

  FIG. 12 is a perspective view of the light emitting light source 300 according to Embodiment 2 of the present invention. FIG. 13 is a cross-sectional view of the light-emitting light source 300 shown in FIG. 12 on a plane including DD and EE lines. 12 and 13, the same components as those in FIGS. 1 and 2 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  12 and 13, the difference from the first embodiment is that both the inner surface and the outer surface of the second electrode 26 do not have specular reflection characteristics but have diffuse reflection characteristics. In order to impart diffuse reflection characteristics to the second electrode 26, it is only necessary to apply diffuse reflection treatment such as coating, sandblasting, surface treatment by chemical treatment, and application of a diffuse reflection sheet to the inner surface and the outer surface of the second electrode 26. Not what you want. In this embodiment, a diffuse reflection sheet (not shown) is attached to both the inner surface and the outer surface of the second electrode 26.

  FIG. 14 and FIG. 15 show examples of a liquid crystal display device 400 in which a plurality of light emitting light sources 300 configured in this way constitute a light emitting device 350 adjacent to each other, and this light emitting device 350 is incorporated. 14 is a plan view showing the configuration of the liquid crystal display device 400, and FIG. 15 is a cross-sectional view taken along the line FF of FIG. In FIG. 15, the cross section is not hatched as in FIG.

  14 and 15, the light source 300 is connected to the reflector 19 and the light source 300 by a lamp holder 20 made of white resin fixed to the reflector 19 made of white resin having diffuse reflection characteristics. Is held and fixed so as to keep a certain distance.

  The plurality of light emission sources 300 are alternately arranged so that the first electrodes 11 of one adjacent light emission source 300 and the second electrode 26 of the other light emission source 300 face each other.

  On the upper surface of the light-emitting device 350, a resin-made diffusion plate 21 having a diffusion transmission characteristic that diffuses light emitted from the light-emitting light source 300 and the reflection plate 19, and a resin-made material that efficiently collects the light from the diffusion plate 21 The lens sheet 22 and a resin-made polarizing sheet 23 that gives polarization to the light from the lens sheet 22 are arranged in an overlapping manner, and further, a liquid crystal panel 24 for forming and displaying an image is arranged thereon. .

  The reflection plate 19, the light emitting device 350, the diffusion plate 21, the lens sheet 22, the polarizing sheet 23, and the liquid crystal panel 24 are housed in a metal (aluminum) housing 25, and the liquid crystal display device 400 is configured from these.

  The luminance distribution characteristics of the liquid crystal display device 400 configured as described above are shown by a solid line and a black circle in FIG. 16 shows a state in which the liquid crystal panel 24 is removed from the liquid crystal display device 400 (surface of the polarizing sheet 23), and the luminance in the tube axis direction (YY line direction in FIG. This was measured at regular intervals using a high-land color shift / luminance simultaneous multipoint measurement system “RISA-COLOR / CD7 type”).

  For comparison, FIG. 16 shows the luminance distribution characteristics of the liquid crystal display device of Embodiment 1 with solid lines and Δ marks.

  From FIG. 16, compared with the liquid crystal display device of Embodiment 1, the liquid crystal display device 400 of this embodiment has further improved luminance distribution characteristics at both ends (about 30 to 40% at the ends). I understand.

  This is because, in the light emitting light source 300, a diffuse reflection sheet (not shown) is attached to the inner surface and the outer surface of the second electrode 26, so that the light emitted from the arc tube 10 is reflected between the reflecting plate 19 and the diffusing plate 21. During the mutual reflection several times, a part of the light is applied to the diffuse reflection sheet of the second electrode 26, so that the light in the vicinity of the second electrode 26 is increased. As a result, the liquid crystal display device The luminance unevenness is further reduced by increasing the luminance at the end portion of 400.

  When the method for obtaining the luminance uniformity described in Embodiment 1 is applied to this embodiment and the luminance uniformity of the liquid crystal display device 400 is obtained, the results shown in Table 2 are obtained.

  As can be seen from Table 2, in the first embodiment, the luminance uniformity of the liquid crystal display device 200 was about 52%, whereas in the present embodiment, the inner surface of the second electrode 26 of the light emission source 300. By attaching a diffuse reflection sheet to the outer surface, the luminance uniformity becomes about 74%, and it can be seen that the luminance distribution characteristics at both ends of the liquid crystal display device 400 are further improved.

  In the above configuration, a liquid crystal display device having a configuration in which a diffusion sheet for further improving the diffusibility is disposed on the diffusion plate 21 or the polarizing sheet 23 is removed by making the light from the light emitting light source 300 stronger. This configuration can be selected according to each design condition.

(Embodiment 3)
In the present embodiment, an example will be described that shows that the light-emitting device and the liquid crystal display device of the present invention have still another excellent feature.

  Specifically, in the first and second embodiments, instead of using the support 13 to hold and fix the arc tube 10, the second electrode 12, and the second electrode 26, This is because the two electrodes 27 themselves have a function of holding and fixing the arc tube 10. Thereby, not only the support 13 used in Embodiment 1 and Embodiment 2 is unnecessary, but also the number of lamp holders 20 used can be reduced. Specific examples thereof will be described below.

  FIG. 17 is an external view of a light emitting light source 500 according to Embodiment 3 of the present invention. 18 is a cross-sectional view of the light-emitting light source 500 shown in FIG. 17 in a plane including the GG line / HH line. 17 and 18, the same components as those in FIGS. 1 and 2 of the first embodiment and FIGS. 12 and 13 of the second embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  17 and 18, the difference from the first and second embodiments is that the second electrode 27 has a function of holding and fixing the arc tube 10.

  In the present embodiment, as shown in FIG. 19, the second electrode 27 is made of a phosphor bronze spring plate having a substantially U-shaped cross section, and has a diffuse reflection characteristic on both the inner surface and the outer surface. Has been given. In addition, the lead wire 15 is fixed by caulking to the lower portion (bottom surface) of the second electrode 27, whereby the second electrode 27 and the lead wire 15 are electrically connected. Furthermore, the second electrode 27 is fixed to the reflection plate 19 by adhesion as shown in FIGS. 21 and 22 to be described later.

  In the present embodiment, a phosphor bronze plate having a spring property is used as the material of the second electrode 27. However, the present invention is not limited to this, and a stainless steel or metal / resin composite member having a spring property may be used. Good. Further, in the present embodiment, the second electrode 27 is fixed to the reflecting plate 19 by bonding, but instead of bonding, the second electrode 27 and the reflecting plate 19 may be formed by integral resin molding. The assembly of both becomes unnecessary, and the assembly process can be simplified.

  FIG. 20 is an arrow view of the light emitting light source 500 shown in FIG. 17 as seen from the I direction, and the arc tube 10 is held and fixed by the semicircular portion 27 a of the second electrode 27.

  21 and 22 show an example of a liquid crystal display device 600 in which a plurality of light-emitting light sources 500 configured in this way constitute a light-emitting device 550 adjacent to each other, and this light-emitting device 550 is incorporated. 21 is a plan view showing the configuration of the liquid crystal display device 600, and FIG. 22 is a cross-sectional view taken along the line JJ of FIG. Note that FIG. 22 is not hatched in the cross section as in FIGS.

  21 and 22, the light emitting light source 500 is reflected by the lamp holder 20 made of white resin and the second electrode 27 that are fixed to the reflecting plate 19 made of white resin having diffuse reflection characteristics by bonding at a plurality of locations. The plate 19 and the light emitting light source 500 are held and fixed so as to keep a certain distance.

  The plurality of light emitting light sources 500 are alternately arranged so that the first electrode 11 of one adjacent light emitting light source 500 and the second electrode 27 of the other light emitting light source 500 face each other.

  On the upper surface of the light-emitting device 550, a resin-made diffusion plate 21 having a diffusion transmission characteristic for diffusing light emitted from the light-emitting light source 500 and the reflection plate 19, and a resin-made material that efficiently collects the light from the diffusion plate 21 The lens sheet 22 and a resin-made polarizing sheet 23 that gives polarization to the light from the lens sheet 22 are arranged in an overlapping manner, and further, a liquid crystal panel 24 for forming and displaying an image is arranged thereon. .

  The reflection plate 19, the light emitting device 550, the diffusion plate 21, the lens sheet 22, the polarizing sheet 23, and the liquid crystal panel 24 are housed in a metal (aluminum) housing 25, and the liquid crystal display device 600 is configured from these.

  With such a configuration, not only the support 13 used in the first and second embodiments is unnecessary, but also the number of lamp holders 20 used can be reduced, so that the light emitting device 550 and the liquid crystal display device 600 are used. Since the assembly process is simplified and the assembly time is shortened, the cost is reduced.

  The embodiments of the present invention have been described above by way of examples. However, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

  Since the light-emitting device of the present invention has no luminance gradient and uniform luminance, it can be applied to various light sources, lighting devices, display devices, and the like. In particular, a liquid crystal display device including the light emitting device of the present invention can be suitably applied to various liquid crystal displays and the like because the luminance distribution is uniform and there is no luminance unevenness.

It is a perspective view of the light emission light source 100 in Embodiment 1 of this invention. It is sectional drawing in the AA and BB line of FIG. It is a perspective view of the support 13 in Embodiment 1 of this invention. It is a perspective view of the 2nd electrode 12 in Embodiment 1 of the present invention. FIG. 6 is a characteristic diagram showing the relationship of the tube surface brightness of the arc tube 10 with respect to the length of the second electrode 12 in Embodiment 1 of the present invention. It is a characteristic view which shows the relationship between the distance of the arc_tube | light_emitting_tube 10 and the 2nd electrode 12, and the ozone amount to generate | occur | produce in Embodiment 1 of this invention. It is a top view which shows the structure of the liquid crystal display device 200 which arranged the light emission light source 100 in multiple numbers in Embodiment 1 of this invention. It is sectional drawing in CC line of FIG. It is a perspective view of the lamp holder 20 in Embodiment 1 of this invention. It is a characteristic view which shows the luminance distribution of the XX line direction of FIG. 7 in the liquid crystal display device of Embodiment 1 of this invention and the conventional liquid crystal display device. It is a figure which shows the luminance measurement position which calculates | requires the luminance uniformity of the liquid crystal display device 200 in Embodiment 1 of this invention. It is a perspective view of the light emission light source 300 in Embodiment 2 of this invention. It is sectional drawing in the DD line | wire and EE line | wire of FIG. It is a top view which shows the structure of the liquid crystal display device 400 which juxtaposed the light emission light source 300 in Embodiment 2 of this invention. It is sectional drawing in the FF line of FIG. It is a characteristic view which shows the luminance distribution of the YY line direction of FIG. 14 in the liquid crystal display device of Embodiment 2 and the liquid crystal display device of Embodiment 1 of this invention. It is a perspective view of the light emission light source 500 in Embodiment 3 of this invention. It is sectional drawing in the GG line and HH line of FIG. It is a perspective view of the 2nd electrode 27 in Embodiment 3 of the present invention. It is the arrow line view which looked at the light emission light source 500 in Embodiment 3 of this invention from the I direction of FIG. It is a top view which shows the structure of the liquid crystal display device 600 which juxtaposed the light emission light source 500 in Embodiment 3 of this invention. It is sectional drawing in the JJ line of FIG. It is sectional drawing of the conventional fluorescent lamp and a liquid crystal display device using the same. It is sectional drawing of the liquid crystal display device which juxtaposed several conventional fluorescent lamps. It is a schematic diagram which shows a mode that a brightness | luminance inclination is made in the conventional fluorescent lamp. It is a schematic diagram which shows a mode that a brightness | luminance inclination cannot be performed in the conventional fluorescent lamp. It is a figure which shows the luminance distribution when the brightness | luminance inclination is made in the conventional fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light emission tube 11 1st electrode 12, 26, 27 2nd electrode 13 Support 14, 15 Lead wire 16 Discharge medium 17 Phosphor layer 18 Lighting circuit 19 Reflector 20 Lamp holder 21 Diffuser 22 Lens sheet 23 Polarizing sheet 24 Liquid crystal panel 25 Housing 100, 300, 500 Light-emitting light source 150, 350, 550 Light-emitting device 200, 400, 600 Liquid crystal display device

Claims (12)

A light-emitting device including a plurality of light-emitting sources,
The light emission source is:
An airtight arc tube,
A discharge medium mainly composed of a rare gas sealed inside the arc tube;
A light emitting layer excited and emitted by the discharge medium;
Including a first electrode and a second electrode for exciting the discharge medium;
The first electrode is disposed at one end of the arc tube,
The second electrode is disposed at the other end of the arc tube,
The light emitting source has a luminance gradient including a high luminance region and a low luminance region between the first electrode and the second electrode,
The plurality of light emitting sources are arranged adjacent to each other, and are alternately arranged so that a high luminance region of one adjacent light emitting light source and a low luminance region of the other light emitting source are opposed to each other. A light emitting device characterized by the above. The arc tube is formed from an elongated tubule,
The first electrode is disposed inside one end of the arc tube,
The second electrode is disposed outside the other end of the arc tube,
The light-emitting device according to claim 1, wherein the first electrodes of one light-emitting light source adjacent to each other and the second electrodes of the other light-emitting light source are alternately arranged.   3. The light emitting device according to claim 2, wherein the second electrode and the arc tube are arranged with a predetermined distance or more therebetween through a gap.   The light emitting device according to claim 3, wherein the gap is narrow at the endmost part of the arc tube and is widened toward the first electrode side.   The light emitting device according to any one of claims 1 to 4, wherein a length L1 of the arc tube and a length L2 of the second electrode satisfy a relationship of 0 <L2 / L1≤0.2.   The light emitting device according to any one of claims 1 to 4, wherein a length L1 of the arc tube and a length L2 of the second electrode satisfy a relationship of 0.01 <L2 / L1 ≦ 0.1.   The light emitting device according to claim 1, wherein the discharge medium contains at least mercury.   The light emitting device according to claim 1, wherein a surface of the second electrode facing the arc tube is subjected to a diffuse reflection process with respect to visible light.   The light emitting device according to any one of claims 1 to 8, wherein a back surface of the second electrode facing the arc tube is subjected to a diffuse reflection process for visible light.   The light emitting device according to claim 1, wherein the second electrode can hold the arc tube.   The light emitting device according to claim 1, further comprising a lighting circuit capable of applying a voltage between the first electrode and the second electrode. A light emitting device according to any one of claims 1 to 11,
A reflecting member that reflects the light emitted from the light emitting device to the liquid crystal panel side;
A condensing member for condensing light from the light emitting device and the reflecting member;
A liquid crystal panel that transmits light from the light collecting member;
A liquid crystal display device comprising: the light emitting device, the reflecting member, the light collecting member, and a housing for holding and fixing the liquid crystal panel.

Images