WO2008038728A1 - Illuminating device and display device - Google Patents

Abstract

A backlight unit is provided with a case (10) having an opening section, a lamp (20) arranged in the case, and a front panel covering the opening section of the case (10). When an X axis is the tube axis of the lamp (20), a Y axis is an axis vertical to the X axis and parallel to the front panel, and a Z axis is an axis vertical to the X axis and the Y axis, the front panel is provided with a light refracting sheet (13) which refracts and outputs light outputted from the lamp (20), and a diffusing/collecting sheet for diffusing and collecting the light outputted from the light refracting sheet (13), and the light refracting sheet (13) refracts and outputs the entered light so that an inequality of θ1>θ2 is satisfied, where θ1 is the incidence angle of light on a Y-Z flat surface, θ2 is an incidence angle, and θ1>0. Thus, even in a case where the number of lamps for a light source is small, luminance nonuniformity is suppressed.

Description

 Specification

 Lighting device and display device

 Technical field

 The present invention relates to a lighting device used as a backlight of a display device such as a liquid crystal display.

And a display device including the lighting device as a light source.

 Background art

 [0002] In recent years, the screen size of liquid crystal display devices such as liquid crystal televisions and liquid crystal monitors has increased.

 Conventionally, as a light source of a backlight unit of a liquid crystal display device, a cold cathode discharge lamp having a small glass bulb has been mainly employed in order to reduce the thickness.

 Although the cold cathode discharge lamp is suitable for thinning the device, the lamp efficiency is not so high, and the power consumption increases as the screen size of the liquid crystal display device increases. Therefore, it tends to refrain from adopting it as the light source of the backlight unit of large liquid crystal display devices.

 [0003] In addition, when the screen size is increased, the glass bulb of the cold cathode discharge lamp becomes longer and the distance between the electrodes increases, so that a higher voltage is applied to light the lamp. Need arises. For this reason, when a cold cathode discharge lamp is used as the light source of the backlight unit of a large liquid crystal display device, there is a demerit that power loss due to leakage current from the booster circuit becomes large.

 [0004] Thus, in recent years, hot cathode type discharge lamps having higher efficiency than cold cathode type discharge lamps have begun to be used as light sources for backlight units of large liquid crystal display devices. In addition, in order to reduce product costs, research and development has been actively conducted on reducing the number of hot cathode discharge lamps that are the light source of the backlight unit.

However, if the number of hot-cathode discharge lamps, which are force light sources, is small, uneven brightness tends to occur in the emitted light emitted from the knocklight unit. That is, on the light exit surface of the backlight unit, high-intensity light is emitted from the area near the position where the hot cathode discharge lamp is disposed, but low from the area away from the position where the hot cathode discharge lamp is disposed. Since only the light of luminance is emitted, the luminance unevenness occurs. [0005] Therefore, in Patent Document 1, a diffusion sheet having a size corresponding to each hot cathode discharge lamp is disposed in a space between the hot cathode discharge lamp and the diffusion plate. Patent Document 1 describes that the occurrence of uneven brightness can be suppressed by disposing the diffusion sheet.

 Patent Document 1: Japanese Patent Laid-Open No. 6-130384

 Disclosure of the invention

 Problems to be solved by the invention

[0006] However, in the configuration of Patent Document 1, it is necessary to separately provide a member for holding each diffusion sheet between the hot cathode discharge lamp and the diffusion plate, which complicates the manufacturing process and reduces the cost. There is concern about becoming high.

 More importantly, in the configuration of Patent Document 1, not all of the light emitted from the hot cathode discharge lamp passes through the diffusion sheet. It will be solved! /!

[0007] The present invention has been made in view of the above problems, and aims to provide an illumination device and a display device in which luminance unevenness is suppressed even when the number of lamps of the light source is small. Target.

 Means for solving the problem

[0008] An illumination device according to the present invention is an illumination device including a casing having an opening, a discharge lamp disposed in the casing, and a front panel covering the opening of the casing. When the tube axis of the discharge lamp is the X axis, the axis perpendicular to the X axis and parallel to the front panel is the Y axis, and the axis perpendicular to the X axis and the Y axis is the Z axis, the front panel is A light refracting member that refracts and emits light emitted from the discharge lamp; and a diffusion and condensing member that diffuses and condenses the light emitted from the light refracting member. — When the incident angle of light in the z plane (the plane parallel to the main surface of the front panel) is Θ 1 and the exit angle is Θ 2 and Θ 1> 0, satisfy the relationship θ 1> Θ 2 It is characterized in that incident light is refracted and emitted.

The invention's effect [0009] As a result of diligent research conducted by the present inventors, the following knowledge about the light diffusing function of the diffusing / condensing member was obtained.

 Conventionally, the incident angle of light incident on the diffusing / condensing member varies. In the region away from the discharge lamp, which is the light source, the light emitted from the discharge lamp enters the diffusion / condensing member at a large incident angle. The diffusion / condensing member has a light diffusion function, but the intensity of the emitted light is highly dependent on the incident angle of light. In other words, even if light that has entered the diffuser condensing member at a large incident angle is diffused by the light diffusing function, the light that is emitted has a large output angle depending on the incident angle. Is done. Light with a large emission angle is difficult to be collected even by the light collecting function of the diffusing / condensing member, so that it is difficult to contribute to the brightness of the lighting device.

 In the present invention, the diffusion / condensing member can reduce the incident angle of light incident on the diffusion / condensing member, particularly in a region away from the discharge lamp. As a result, the emission angle of light diffused and emitted by the diffusion function of the diffusion / condensing member becomes small. Accordingly, the emitted light is easily collected by the light collecting function of the diffusing / condensing member, which contributes to increasing the luminance in a region away from the discharge lamp.

 [0011] Thus, according to the present invention, light that is stronger than before is emitted, particularly in a region away from the discharge lamp, so that it is possible to improve the uneven brightness of the emitted light of the illumination device that has conventionally occurred. Touch with S.

 Here, the light refracting member suppresses the transmittance of light emitted from the discharge lamp with a small incident angle with respect to the member surface, and gradually increases the light transmittance as the incident angle increases. It is desirable to adjust the transmission of the light emitted from the discharge lamp.

 [0012] With the above configuration, among the light radiated from the discharge lamp, the light having a smaller incident angle with respect to the light refracting member is suppressed by the light refracting member, and the incident angle is larger. The more light is transmitted, the more light is transmitted through the photorefractive member. As a result, even when the number of lamps of the light source is small, the luminance unevenness is improved for the light emitted from the light emitting surface of the illumination device.

In the above, the light refraction member has a prism row, and the prism row Record

 It is desirable to be arranged in parallel with the tube axis of the discharge lamp!

[0013] Thus, with a simple configuration, it is possible to suppress the transmission of light emitted to a region near the discharge lamp and to increase the transmission of light emitted to a region away from the discharge lamp.

 Here, in the above, it is desirable that the prism row is formed on all the portions of the photorefractive member facing the diffusion / condensing member.

 As a result, uniform light is incident on the diffusing / condensing member, so that the luminance unevenness of the illumination device can be reduced.

[0014] Here, in the above, each prism of the prism row has a substantially triangular cross-section perpendicular to the tube axis of the discharge lamp, and the apex angle of each prism is 80 ° or more 120 It is desirable that the vertical angle portion of each prism is opposed to the diffusion / condensing member.

 This is because, if the apex angle of each prism is less than 80 °, it is difficult to maintain the shape from the viewpoint of structural mechanics, and if it exceeds 120 °, the light condensing characteristics are deteriorated too much.

[0015] In the above, it is desirable that the angle of the apex angle of each prism is 90 °.

 This is because it is known that when the apex angle of each prism is 90 °, the light condensing characteristic of the photorefractive member is most enhanced.

 Here, in the above, it is desirable that an auxiliary diffusing member for diffusing the light emitted by the discharge lamp is disposed between the discharge lamp and the light refraction member.

[0016] By disposing the auxiliary diffusion member, it is possible to suppress luminance unevenness and to reduce the thickness of the casing.

 Also, in the above, a plurality of the discharge lamps are arranged in parallel in the casing, the interval between the discharge lamps is P [mm], and the tube axis of the discharge lamp and the front panel are arranged. When the distance is d [mm], the distance between the tube axis of the discharge lamp and the bottom surface of the casing is f [mm], and the emission diameter in the thickness direction of the casing of the discharge lamp is rl [mm], 0 It is desirable that 10≤ (d + f) / P <0. 40 and 1.7 <(d + f) / rl <4

[0017] In order to satisfy this condition, a discharge lamp is provided in the casing to reduce luminance. The required number of discharge lamps can be reduced while suppressing the above.

 Here, in the above, the discharge lamp is provided with a glass bulb having a flat shape in a cross section perpendicular to the tube axis, and is arranged so that the long inner diameter of the flat shape is parallel to the bottom surface of the casing. desirable.

 [0018] In the above configuration! /, The glass bulb has a flat shape! /. Therefore, by arranging the lamp with the short inner diameter of the glass bulb in the thickness direction of the backlight unit, the backlight unit It is possible to reduce the thickness. In this specification, the term “flat shape” refers to a shape in which a circular glass tube is crushed in the vertical direction, the inner diameter in the vertical direction is the short inner diameter, and the inner diameter in the left-right direction is the long inner diameter. In addition to a shape including two flat portions facing each other and a curved portion connecting them, an elliptical shape in which all of the contours are expressed by curves is also included.

 [0019] A display device according to the present invention includes any one of the illumination devices described above as a light source.

 As a result, since the above-described illumination device with less luminance unevenness is provided as a light source, a display device in which the luminance distribution of light emitted from the display surface is uniform can be provided.

 FIG. 1 is a diagram showing a liquid crystal display device according to the present invention, and is a diagram in which a part is cut away so that the inside can be seen.

 FIG. 2 is a schematic perspective view showing a configuration of a backlight unit 5 for a liquid crystal display having an aspect ratio of 16: 9 according to the present embodiment.

 FIG. 3 is a cross-sectional view taken along the line AA in FIG.

 FIG. 4 is a cross-sectional view of a backlight unit for explaining the light refraction sheet 13.

 FIG. 5 is a cross-sectional view of a backlight unit for explaining the function of the light refraction sheet 13.

 FIG. 6 is a graph showing the luminance distribution characteristics of the backlight unit.

FIG. 7 is a diagram showing a configuration of a hot cathode discharge lamp 20 according to the present embodiment, in which FIG. 7 (a) is a cross-sectional plan view, and FIG. — Cross-sectional view taken along section B. FIG. 8 is a cross-sectional view showing a configuration of a backlight unit according to a modification.

 FIG. 9] is a cross-sectional view of a hot cathode discharge lamp according to a modification.

 Explanation of symbols

 1 Liquid crystal display

 3 LCD screen unit

 5 Beckhuituni

 10 housing

 11 Inside

 12 Auxiliary reflector

 13 Light refraction sheet

 14 Diffuser

 15 Diffusion sheet

 16 Lens sheet

 18 冃 IJ side panel

 17 Polarizing sheet

 19 Auxiliary diffusion sheet

 20 Hot cathode discharger

 22 Glasnore

 24 tti film

 26 Phosphor layer

 BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, a backlight unit and a liquid crystal display device according to an embodiment of the present invention will be described with reference to the drawings.

 <Configuration of liquid crystal display device>

 First, the configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a liquid crystal display device according to the present invention, and is a diagram in which a part is cut away so that an internal state can be seen.

The liquid crystal display device 1 is, for example, a liquid crystal color television, and includes a liquid crystal screen unit 3 and a backlight. Unit 5 and the main unit 4 are assembled. The liquid crystal screen unit 3 includes, for example, a color filter substrate, a liquid crystal, a TFT substrate, a drive module and the like (not shown), and displays a color image based on an image signal from the outside of the liquid crystal screen unit 3. On screen 6 of 3

Ik small.

 [0024] <Configuration of backlight unit>

 The configuration of the backlight unit according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic perspective view showing a configuration of a backlight unit 5 for a liquid crystal display having an aspect ratio of 16: 9 according to the present embodiment. In the figure, a part of the front panel 18 is cut away to show the internal structure.

As shown in FIG. 2, the backlight unit 5 has a plurality of hot-cathode discharge lamps (hereinafter referred to as “lamps”) 20 and an opening that houses these lamps 20. A housing 10 and a front panel 18 that covers the opening of the housing 10 are provided.

 The housing 10 is formed of, for example, a box body having an opening made of aluminum sheet metal, and an inner surface thereof.

11 is affixed with a polyester sheet having white diffuse reflection characteristics (in this example, E60L manufactured by Toray is used).

[0026] The lamp 20 has a straight tube shape, and in the present embodiment, four lamps 20 are arranged in the casing 10 in a direct manner and are electrically connected in parallel. The lamp 20 is constant-current controlled by a lighting circuit (not shown). The configuration of the lamp 20 will be described later. In the casing 10 between the lamps 20, an auxiliary reflector 12 having a triangular prism shape is disposed.

. The auxiliary reflector 12 efficiently reflects the direct light emitted from the lamp 20 and the indirect light emitted from the lamp 20 and reflected by the front panel 18 to the front panel 18.

[0027] The opening of the housing 10 is covered with a translucent front panel 18 in which a light refracting sheet 13, a diffusing plate 14, a diffusing sheet 15, a lens sheet 16 and a polarizing sheet 17 are laminated, No foreign matter such as dust or dust enters! /, And sealed! /

The function of the light refraction sheet 13 in the front panel 18 will be described in detail later. The diffusing plate 14 and the diffusing sheet 15 diffuse light transmitted through the light refraction sheet 13. The lens sheet 16 collects the light transmitted through the diffuser plate 14 and the diffuser sheet 15 and deflects it in the normal direction of the lens sheet 16. The emitted light is configured to irradiate the front surface uniformly over the entire surface (light emitting surface) of the front panel 18.

 Next, the arrangement position of the lamp 20 in the housing 10 will be described with reference to FIG. FIG. 3 is a cross-sectional view taken along the line AA in FIG. The light refracting sheet 13 has a triangular prism IJT, but is arranged so that the triangular apex of the prism row abuts on the diffusing plate 14. An air layer 19 is formed in the gap. In FIG. 3, the tube axis direction of the lamp 20 is the X axis, the axis perpendicular to the X axis and parallel to the front panel 18 is the Y axis, and the axis perpendicular to the X and Y axes is the Z axis.

 As shown in FIG. 3, the lamps 20 are arranged in parallel at equal intervals with a distance P [mm]. Each lamp 20 is held by a conductive holder (not shown) fixed to the bottom surface of the housing 10 and electrically connected to the lighting circuit.

 The lamp 20 is disposed so that the coil axis of the electrode coil 31 is parallel to the bottom surface of the housing 10 and the distance from the front panel 18 is d [mm]. At this time, the distance between the coil axis of the electrode coil 31 and the bottom surface of the housing 10 is f [mm]. In the lamp 20 thus arranged, the emission diameter rl [mm] in the thickness direction of the casing 10 is the short inner diameter, and the emission diameter r2 [mm] in the direction parallel to the bottom surface is the long inner diameter.

 [0030] where the distances P, d, f are

 0. 10≤ (d + f) / P <0. 40 (Equation 1)

 It is preferable that the relationship is satisfied. If (d + f) / P is less than 0.1, uneven brightness cannot be eliminated even with the configuration in which the photorefractive sheet 13 is disposed as in the present embodiment. This is because if d + f) / P is 0.4 or more, the effect of reducing the number of lamps 20 does not occur.

 [0031] Further, considering the number of lamps and the thickness of the lighting device, the distances P, d, f are

 0. 30≤ (d + f) /P≤0.35 (Equation 2)

 It is preferable that the relationship is satisfied.

Furthermore, this is an empirical formula obtained as a result of actual trial manufacture and evaluation of a backlight unit with a thickness d + f of 20 to 60 mm using a lamp with an emission diameter rl of 14 mm. For lamps with different rl values, 1. 7 <(d + f) / rl <4 (Equation 3)

 It is preferable that the relationship is satisfied. When (d + f) / rl is 1.7 or less, the function of the light refracting sheet 13 cannot be sufficiently exhibited because the lamp emitting surface and the light refracting sheet 13 are too close to each other. Further, when the force is (d + f) / rl force or higher, a high degree of uniformity can be obtained without necessarily arranging the light refraction sheet 13.

[0032] Next, the light refraction sheet 13 will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional view of the backlight unit 5 for explaining the optical folding sheet 13. In FIG. 4, only the light refraction sheet 13 of the front panel 18 is shown, and the other diffuser plate 14, lens sheet 16 and the like are not shown.

 The photorefractive sheet 13 has a triangular prism IJT having a structure in which a plurality of triangular prisms 13b made of acrylic resin are joined to a flat plate layer 13a made of polyester resin. The light bending sheet 13 is arranged so that the longitudinal direction of the triangular prism IJT is substantially parallel to the tube axis direction of the lamp 20.

 The light incident on the light refraction sheet 13 at an incident angle θ 1 is refracted by the polyester resin layer 13 a and the attaly resin layer 13 b and is emitted toward the diffusion plate 14 at an emission angle Θ 2. The emitted light is incident on the diffusion plate 14 at an incident angle Θ 2.

 As a result of diligent research conducted by the present inventors, the following knowledge about the light diffusion function of the diffusion plate 14 was obtained.

 Conventionally, the incident angle of light incident on the diffusion plate 14 varies. In a region away from the lamp 20 as the light source, the light emitted from the lamp 20 enters the diffuser plate 14 at a large incident angle. The diffuser plate 14 has a light diffusing function, but the intensity of emitted light is highly dependent on the incident angle of light. That is, even if light incident on the diffuser plate 14 at a large incident angle is diffused by the light diffusion function, the light emitted from the diffuser plate 14 still has a large output angle depending on the incident angle. A lot of light is emitted. Light having a large emission angle is not easily collected by the light collecting function of the lens sheet 16, and therefore does not contribute to the brightness of the backlight unit 5.

In the present embodiment, the light refraction sheet 13 can reduce the incident angle Θ 2 of light incident on the diffuser plate 14, particularly in a region away from the lamp 20. As a result, The outgoing angle of light diffused and emitted by the diffusion function of the scattering plate 14 is reduced. Accordingly, the emitted light is easily condensed by the condensing function of the lens sheet 16, which contributes to increasing the luminance in a region away from the lamp 20.

 As described above, according to the configuration according to the present embodiment, light that is stronger than the conventional light is emitted particularly in the region away from the lamp 20, so that the backlight unit 5 that has conventionally occurred can be emitted. It is possible to improve uneven brightness of incident light.

 Next, the light refraction sheet 13 will be described with reference to FIG. FIG. 5 is a cross-sectional view of the backlight unit for explaining the function of the light refraction sheet 13. In FIG. 5, only the light refraction sheet 13 of the front panel 18 is illustrated, and the other diffusion plate 14, lens sheet 16 and the like are not illustrated.

 [0037] The light L1 emitted in the vicinity of the lamp 20 and incident on the light refraction sheet 13 at a small incident angle Θ a 1 passes through the apex angle of the triangular prism array で at a refraction angle θ β 1 and is From the apex of the prism, the light is emitted perpendicular to the main surface of the light refraction sheet 13. When the refractive index of air is η / 3 and the refractive index of the polyester resin layer 13a of the light refracting sheet 13 is η / 3, the incident angle Θa1 and the refractive angle Θ / 31 satisfy Snell's law. . That is, the incident angle θ α 1, the refraction angle Θ / 31, the refractive index, and the refractive index η / 3 are

 η α-sin (e α 1) = n / 3-sin (θ β 1) (Equation 3)

 Meet the relationship.

 [0038] On the other hand, the light L2 emitted to the region near the lamp 20 and incident on the photorefractive sheet 13 at the incident angle Θa2 is refracted at the refractive angle θβ2 in the polyester resin layer 13a, Since the acrylic resin layer 13b is triangular, the total reflection occurs between the acrylic resin layer 13b and the air layer 19. The light reflected on the slope of the triangular prism is emitted toward the bottom surface of the housing 10. The reflected light is reflected by the inner surface 11 of the housing 10, the auxiliary reflecting plate 12, the glass bulb of the lamp 20, etc., reenters the light refraction sheet 13, and is used effectively.

[0039] Light emitted to a region away from the position where the lamp 20 is disposed, that is, L3 and L4 incident on the light refraction sheet 13 at large incident angles θ α 3 and θ α 4 are the light refraction sheet 13 , Refracts according to Snell's law, passes through the apex angle of the triangular prism, It is emitted as parallel light substantially perpendicular to the main surface.

 That is, by disposing the photorefractive sheet 13 as described above, it has the same effect as if the region force light that should not be irradiated with direct light is emitted.

 That is, by disposing the light refracting sheet 13 between the lamp 20 and the diffusing plate 14, the light emitted from the lamp 20 passes through the light refracting sheet 13, thereby diffusing the plate 14. The light emitted from the front panel 18 after passing through the diffusing plate 14 and the lens sheet is also uniform with local high and low brightness. Thus, according to the present embodiment, even when the number of lamps 20 as the light source is small, the transmission of direct light is suppressed, and a part of the reduced light is emitted from the conventional direct light. Since the light is emitted from a region that has not been used, the luminance unevenness of the backlight unit, which has been a problem in the past, can be improved.

 [0041] <Effect>

 Next, the effect of the backlight unit according to the present embodiment will be described with reference to FIG. Fig. 6 is a graph showing the luminance distribution characteristics of the nocrite unit. The graph indicated by the solid line is the data of the backlight unit 5 (example) according to the present embodiment, and the graph indicated by the broken line is the data of the backlight unit according to the conventional example (comparative example). It is. The vertical axis of the graph is the front panel surface brightness (relative value) [%], and the horizontal axis is the brightness measurement position [mm]. The 0 mm position on the horizontal axis corresponds to the lowermost position of the front panel 18, and the 400 mm position corresponds to the uppermost position of the front panel.

As shown in FIG. 6, in the comparative example, in the region far from the lamp 20, it can be seen that the luminance of the front panel surface is lower than 40%, and uneven luminance occurs. In contrast, in this example, the brightness of the front panel surface of 90% or less is maintained even in a region far from the lamp 20, and this example has significantly improved brightness unevenness compared to the comparative example. I understand that.

 [Configuration of lamp 20]

 Next, the configuration of the lamp 20 will be described. FIG. 7 is a diagram showing a configuration of a hot cathode discharge lamp (hereinafter sometimes simply referred to as “lamp”) 20 according to the present embodiment, in which FIG. (b) is a cross-sectional view taken along the section B-B.

[0043] The lamp 20 is provided with a straight tubular glass bulb 22 and both ends of the glass bulb 22. It has a pair of electrodes 30a, 30b.

 The glass bulb 22 is made of barium strontium silicate glass (soft glass with a softening point of 675 ° C). As shown in FIG. 7 (b), the glass bulb 22 has an elliptical cross section perpendicular to the tube axis and having a major inner diameter C1 and a minor inner diameter C2. As described above, since the glass bulb 22 has an elliptical shape, the lamp 20 is arranged with the short inner diameter of the glass bulb 22 in the thickness direction of the backlight unit 5, that is, the short inner diameter of the glass bulb 22 is arranged on the front panel 18. On the other hand, the backlight unit 5 can be made thin by arranging it vertically.

 In addition, an exhaust pipe 28 is sealed at one end (left end portion in the drawing) of the glass bulb 22! The exhaust pipe 28 is used when exhausting the inside of the glass bulb 22 or enclosing a rare gas, and is sealed after the exhaust is enclosed. By providing the exhaust pipe 28 at one end rather than at both ends of the glass bulb 22, the coldest spot can be controlled easily. In other words, if it is provided at both ends, it is not known where the coldest spot can be made.

 [0045] The electrodes 30a, 30b are tripnorecoinole, 6.5-turn electrode coinores 31a, 31b, and a pair of reed springs 32a, 32b, 33a, 33b carrying the electrode coinores 31a, 31b, The reed springs 32 a, 32 b, 33 a, and 33 b hold the glass beads 34 a and 34 b that hold the force. The electrode coinores 31a and 3 lb are made of, for example, tungsten, and are coated with oxides of strontium, calcium, and normo!

 A protective film 24 made of alumina is formed on the inner surface of the glass bulb 22. Protective film

 A phosphor layer 26 is laminated on 24. The phosphor in the phosphor layer 26 is red (Y

 2

○: Eu), green (LaPO: Ce, Tb) and blue (BaMg Al 2 O: Eu, Mn)

3 4 3 2 16 27

 Using a mixture of rare earth phosphors.

 The glass bulb 22 is filled with about 5 mg of mercury 21 and argon (Ar) with a pressure of 500 Pa at room temperature as a buffer rare gas!

[0047] Mercury 21 enclosed in glass bulb 22 may be enclosed in the form of amalgam such as zinc mercury, tin mercury, bismuth, indium mercury, etc. in addition to mercury alone. Here, the specifications such as the dimensions of the lamp 20 when used in a backlight unit for a 45-inch liquid crystal display are described.

The inner diameter C1 of the glass bulb 22 is 17 mm, the shorter inner diameter C2 is 10 mm, and the total length is 1010 mm. The interelectrode distance Le is 950 mm and the tube wall load We is 0.05 (W / cm ² ). The tube wall load is a value obtained by dividing the lamp power by the inner surface area of the portion of the glass bulb 22 corresponding to the interelectrode distance Le.

 [0048] As described above, since the glass bulb has a flat shape! /, The hot-cathode discharge lamp is provided with the short inner diameter of the glass bulb in the thickness direction of the backlight unit 5, thereby obtaining a backlight unit. 5 can be made thinner.

 Further, when the distance from the lamp 20 in the casing 10 of the backlight unit 5 to the liquid crystal panel is equal to the distance between the lamps 20 of each lamp 20 arranged in the casing 10 of the knock light unit 5, the liquid crystal display It is known that brightness unevenness can be suppressed. In the present embodiment, since the glass bulb 22 has an oval shape, the distance from the lamp 20 to the liquid crystal panel (not shown) can be increased with respect to the length of the electrode coils 31a and 31b. . Along with this, even if the distance between the lamps 20 arranged in the casing 10 of the backlight unit 5 is increased to a size equal to the distance from the lamp 20 to the liquid crystal panel, the luminance unevenness is suppressed. The distance between the lamps 20 arranged in the housing 10 can be increased, and the number of lamps 20 necessary as a light source can be reduced. As a result, the number of parts required for the knocklight unit 5 can be reduced, which contributes to the cost reduction of the backlight unit 5.

 In FIG. 2, the force lamp 20 that describes the configuration in which four lamps 20 are arranged has the number of lamps 20 arranged in the casing 10 of the backlight unit 5 as follows: It may be appropriately changed according to the screen size of the liquid crystal display device.

 <Modification>

 As described above, the present invention has been described based on the embodiments. The content of the present invention is of course not limited to the specific examples shown in the above embodiments. For example, the following modifications are possible. Can think.

[0050] (1) In the above description, the configuration in which the light refraction sheet 13 has the triangular prism IJT has been described. However, the present invention is not limited to this, and each prism in the prism array has a trapezoidal shape, a polygonal shape, or a semicircular shape. May be. In addition, it is not necessary for all the prism rows to have the same shape. For example, in the region near the position where the hot cathode discharge lamp is disposed, each prism is triangular, In a region away from the cathode discharge lamp, the nuclear prism may be semicircular! /.

 [0051] (2) In the above, the configuration in which the light refraction sheet 13 has a prism row has been described.

 The 1S photorefractive member does not necessarily have a prism row. For example, the photorefractive sheet 13 has a refractive index distribution in which the refractive index gradually decreases as the refractive index at the position corresponding to the lamp 20 increases and moves away from the discharge lamp from that position. It may be a configuration. As a result, it is possible to suppress the transmittance of the light emitted to the region near the lamp 20 and to increase the transmittance of the light emitted to the region far from the lamp 20, and thus, the number of the lamps 20 as the light source. Even when the amount of light is small, the luminance unevenness of the backlight unit 5 can be improved.

 [0052] (3) In the above description, the configuration in which the light refraction sheet 13 is in contact with the diffusion plate 14 has been described. However, the present invention is not limited to this. It is sufficient if the light refracting sheet 13 is disposed between the lamp 20 and the diffuser plate 14, that is, the light refracting sheet 13 is not in surface contact with the diffuser plate 14 but separated from the diffuser plate 14. There may be. However, in order to reduce the distance d shown in FIG. 3 and reduce the thickness of the device, it is preferable that the photorefractive sheet 13 is disposed so that the apex of the prism is in contact with the diffusion plate 14. .

 [0053] (4) In the above description, the force S described for the case where the diffusion plate 14, the diffusion sheet 15, and the lens sheet 16 are each independently separate, for example, instead of these, A single diffusion / condensing sheet having the function of condensing the emitted light after being diffused may be used.

 (5) If the distance d between the lamp 20 and the light refracting sheet 13 is reduced in FIG. 3 in order to reduce the thickness of the device, the area from which the direct light from the lamp 20 is emitted becomes narrower, resulting in uneven brightness. Will be encouraged. Therefore, by adopting a configuration according to the following modification, it is possible to suppress uneven brightness even if the device is made thinner.

FIG. 8 is a cross-sectional view showing a configuration of a backlight unit according to a modification. As shown in FIG. 8, an auxiliary diffusion sheet 19 may be disposed in the space between the lamp 20 and the front panel 18. Thereby, since the direct light intensity of the lamp 20 can be reduced, the distance d can be reduced, and the apparatus can be thinned. (6) In the above description, the glass bulb of the lamp 20 is not limited to the force described for an elliptical section perpendicular to the tube axis, as shown in FIG. 7 (b). Any shape having an inner diameter may be used. FIG. 9 is a cross-sectional view of a hot cathode discharge lamp according to a modification. For example, it may have a flat shape as shown in FIG. 9 (a), or may have a rectangular shape as shown in FIG. 9 (b). In these cases as well, since the major inner diameter C1 is larger than the minor inner diameter C2, the force S can be increased by increasing the axial length of the electrode coil. Further, by arranging the glass bulb of the lamp 20 so that the short inner diameter C2 is perpendicular to the liquid crystal panel surface, it is possible to make the device thinner.

[0055] (7) In the above description, the glass bulb of the lamp 20 is described as being linear in appearance, but is not limited thereto. For example, the glass bulb of the lamp 20 is U-shaped or U-shaped in appearance. It may have other shapes such as a shape.

 In this case, the glass bulb of the lamp 20 may have an annular shape. In this case, the prism rows of the light refracting sheet 13 should be arranged in an annular shape parallel to the axis of the glass bulb when viewed in plan. is required. Also in this case, the luminance unevenness of the backlight unit can be reduced.

[0056] (8) In the above description, the case where argon and krypton are sealed as the rare gas for buffering has been described, but in addition to these, neon and xenon may be sealed. Since xenon has a large atomic mass, it suppresses the scattering of the emitter applied to the electrode coil. Encapsulating xenon can further extend the service life.

 (9) In the above description, the protective film 24 is formed on the inner surface of the glass bulb 22, but the protective film 24 may not be formed.

[0057] (10) In the above description, the case where a hot cathode discharge lamp is employed as the light source of the knock light unit has been described. However, the present invention is not limited to this. For example, instead of a hot cathode discharge lamp, a cold cathode is used. Type discharge lamps, external electrode type discharge lamps, or other discharge lamps may be employed as the light source of the backlight unit. Further, instead of a general discharge lamp, a linear light source in which LEDs and light bulbs are linearly arranged may be used. Even in these cases, according to the present invention, even with a small number of! / And the number of lamps, the brightness unevenness can be improved by the same mechanism as described above. (11) In the above, the force described by taking the backlight unit as an example of the illumination device is not limited to this. For example, the illumination device is related to a housing and the present embodiment disposed in the housing. A general lighting unit including a hot cathode discharge lamp.

 (12) In the above description, the liquid crystal display device has been described as an example of the display device. However, the present invention is not limited to this, and examples of the display device include a housing and the present embodiment disposed in the housing. The signboard apparatus provided with the hot cathode type discharge lamp of the form may be sufficient.

 Industrial applicability

[0059] The present invention can be widely applied to lighting devices and display devices. In addition, the present invention can provide a lighting device and a display device in which unevenness in luminance is suppressed even when the number of lamps of the light source is small, so that the industrial utility value thereof is extremely high. .

Claims

The scope of the claims  [1] A lighting device comprising a housing having an opening, a discharge lamp disposed in the housing, and a front panel covering the opening of the housing,  When the tube axis of the discharge lamp is the X axis, the axis perpendicular to the X axis and parallel to the front panel is the Y axis, and the axis perpendicular to the X axis and the Y axis is the Z axis,  The front panel is  A light refracting member that refracts and emits light emitted from the discharge lamp; and a diffusion / condensing member that diffuses and condenses the light refracted by the light refracting member force.  When the incident angle of light on the Y—Z plane is Θ 1 and the exit angle is Θ 2 and θ 1> 0, θ 1> Θ 2  Refracting incident light to satisfy the relationship  A lighting device characterized by the above. [2] The photorefractive member is  Among the light emitted from the discharge lamp, light having a small incident angle with respect to the surface of the member suppresses the transmittance, and gradually increases the light transmittance as the incident angle increases, and is emitted from the discharge lamp. Adjusting light transmission  The lighting device according to claim 1. [3] The photorefractive member has a prism array,  3. The illumination device according to claim 1, wherein the prism row is arranged in parallel with the tube axis of the discharge lamp! /. [4] The prism rows are formed on all portions of the photorefractive member facing the diffusing / condensing member! /  The lighting device according to claim 3. [5] Each prism in the prism row has a substantially triangular cross-sectional shape perpendicular to the tube axis of the discharge lamp, and the apex angle of each prism is not less than 80 ° and not more than 120 °, The apex angle portion of each prism is opposite to the diffuser condensing member The lighting device according to claim 3 or claim 4, characterized by the above. 6. The illumination device according to claim 5, wherein an apex angle of each prism is 90 °.  [7] An auxiliary diffusing member for diffusing the light emitted by the discharge lamp is disposed between the discharge lamp and the light refraction member.  The lighting device according to any one of claims 1 to 6, wherein: [8] In the housing, a plurality of the discharge lamps are arranged in parallel,  The interval between the discharge lamps is P [mm], the distance between the discharge lamp tube axis and the front panel is d [mm], and the distance between the discharge lamp tube axis and the bottom surface of the housing is f [mm]. mm], where the emission diameter in the thickness direction of the casing of the discharge lamp is rl [mm]  0. 10≤ (d + f) / P 0. 40, force, 1.7 (d + f) / rl <4  Meet the relationship  The lighting device according to any one of claims 1 to 7, characterized by: [9] The discharge lamp includes a glass bulb having a flat cross section perpendicular to the tube axis,  9. The illumination device according to claim 1, wherein a flat inner diameter is arranged so as to be parallel to a bottom surface of the casing. [10] A lighting device comprising a housing having an opening, a discharge lamp disposed in the housing, and a front panel covering the opening of the housing,  The front panel is  A light refracting member that refracts and emits light emitted from the discharge lamp; and a diffusion / condensing member that diffuses and condenses the light refracted by the light refracting member force.  When the incident angle of light on the plane parallel to the main surface of the front panel is Θ1, the outgoing angle is Θ2, and Θ1> 0,  θ 1> Θ 2  Refracting incident light to satisfy the relationship  A lighting device characterized by the above. [11] A display device comprising the illumination device according to any one of claims 1 to 10 as a light source.