KR20090058514A - 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 Theta1>Theta2 is satisfied, where Theta1 is the incidence angle of light on a Y-Z flat surface, Theta2 is an incidence angle, and Theta1>0. Thus, even in a case where the number of lamps for a light source is small, luminance nonuniformity is suppressed.

Description

Lighting and display device {ILLUMINATING DEVICE AND DISPLAY DEVICE}

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.

In recent years, screen sizes of liquid crystal display devices such as liquid crystal televisions and liquid crystal monitors have increased in size. Conventionally, a cold cathode discharge lamp having a small diameter of a glass bulb is mainly employed as a light source for a backlight unit of a liquid crystal display device.

The cold cathode discharge lamp is suitable for thinning the device, but the lamp efficiency is not so high, and the power consumption increases with the enlargement of the screen size of the liquid crystal display device. Therefore, the light source of the backlight unit of the liquid crystal display device from the viewpoint of energy saving. There is a tendency to refrain from adoption as a company.

In addition, when the screen size is enlarged, the length of the glass bulb of the cold cathode discharge lamp becomes longer and the distance between the electrodes becomes larger. Therefore, there is a necessity to apply a higher high voltage to turn on the lamp. For this reason, when a cold cathode discharge lamp is employed as a light source of a backlight unit of a large liquid crystal display device, there is a disadvantage in that power loss due to leakage current from the boost circuit is increased.

Therefore, in recent years, a hot cathode discharge lamp, which is more efficient than a cold cathode discharge lamp, has been adopted as a light source of a backlight unit of a large LCD.

In addition, research and development have been actively conducted to reduce the number of thermo-cathode discharge lamps that are light sources of a backlight unit in order to suppress product costs.

However, when the number of the thermal cathode discharge lamps as the light source is small, luminance unevenness is likely to occur in the emitted light emitted by the backlight unit. That is, in the light exit surface of the backlight unit, light of high brightness is emitted from the vicinity of the arrangement position of the thermocathode discharge lamp, but only light of low brightness is emitted from the area away from the arrangement position of the thermocathode discharge lamp. Therefore, unevenness of luminance occurs.

Therefore, in Patent Document 1, a diffusion sheet having a size corresponding to a hot cathode discharge lamp is arranged in a space between the hot cathode discharge lamp and the diffusion plate. Patent Literature 1 describes that the occurrence of luminance unevenness can be suppressed by disposing the diffusion sheet.

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

However, in the structure of patent document 1, it is necessary to arrange | position the member which supports each diffusion sheet separately between a hot cathode discharge lamp and a diffusion plate, and there exists a inconvenience that a manufacturing process becomes complicated and it becomes expensive.

More importantly, in the configuration of Patent Literature 1, not all of the light emitted from the hot cathode discharge lamp passes through the diffusion sheet, so that the problem of luminance unevenness is not solved.

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

The lighting apparatus of the present invention is a lighting apparatus having a frame having an opening, a discharge lamp disposed in the frame, and a front panel covering the opening of the frame, wherein the tube axis of the discharge lamp is the X axis and the X axis. When the axis perpendicular to and parallel to the front panel is set to the Y axis, the axis perpendicular to the X axis, and the Z axis to the Z axis, the front panel includes a light refracting member that emits light by refracting light emitted from the discharge lamp; A diffusing / condensing member for diffusing and condensing the light emitted from the light refracting member, wherein the light refracting member has an incidence angle of light on the YZ plane as θ1 and an outgoing angle of θ2, and when θ1> 0, θ1> The incident light is refracted to emit light so as to satisfy the relationship of θ2.

The following findings were acquired about the light-diffusion function of a diffusing and condensing member by the earnest research of this inventor.

Conventionally, the incidence angle of light incident on the diffusion / condensing member is varied. In the area away from the discharge lamp as the light source, the light emitted from the discharge lamp is incident on 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 the light. That is, even if light incident on the diffusion / condensing member at a large incident angle is diffused by the light diffusing function, the emitted light also emits a lot of light having a large exit angle depending on the incident angle. Light having a large exit angle is hardly condensed even by the light condensing function of the diffusion / condensing member, and thus it is difficult to contribute to the brightness of the lighting apparatus.

In the present invention, the incidence angle of light incident on the diffusion / condensing member can be made small by the diffusion / condensing member, particularly in a region away from the discharge lamp. Thereby, the emission angle of the light which is diffused and emitted by the diffusion function of the said diffusion / condensing member becomes small. Therefore, the emitted light tends to be condensed by the light condensing function of the diffusion / condensing member, thus contributing to increasing the luminance of the region away from the discharge lamp.

As described above, according to the present invention, since particularly stronger light is emitted in the area away from the discharge lamp, the luminance unevenness of the emitted light of the conventionally generated lighting apparatus can be improved.

Here, the light refracting member suppresses the transmittance of the small incident angle to the surface of the member of the light emitted by the discharge lamp, and gradually increases the transmittance of the light as the incident angle increases, thereby reducing the transmittance of the light emitted from the discharge lamp. It is preferable to adjust.

With this arrangement, the transmittance is suppressed by the light refraction member as the light having a small incident angle with respect to the light refraction member among the light emitted by the discharge lamp, and the light that transmits through the light refraction member is increased as the light having a large incident angle is larger. As a result, even when the number of lamps of the light source is small, the luminance unevenness is improved with respect to the light emitted from the light exit surface of the lighting apparatus.

In the above, it is preferable that the optical refraction member has a prism row, and the prism rows are arranged in parallel with the tube axis of the discharge lamp.

This makes it possible to suppress the transmittance of the light radiated to the region near the discharge lamp with a simple configuration and to improve the transmittance of the light radiated to the area away from the discharge lamp.

Here, it is preferable that the said prism row is formed in the whole part which opposes the said diffused / condensing member in the said optical refraction member.

As a result, uniform light is incident on the light converging / diffusing member, thereby improving luminance unevenness of the lighting apparatus.

Here, in the prism, each of the prism of the prism row has a substantially triangular cross-sectional shape perpendicular to the tube axis of the discharge lamp, the angle of the vertex angle of each prism is 80 ° or more and 120 ° or less, the vertex angle portion of each prism It is preferable to oppose the said diffusion / condensing member.

This is because if the vertex angle of each prism is less than 80 °, it is difficult to maintain its shape from the point of structural mechanics, and if it exceeds 120 °, the condensing characteristic is too low.

Moreover, in the above, it is preferable that the angle of the vertex angle of each said prism is 90 degrees.

It is because it is known that the condensing characteristic of the said light refracting member becomes the highest when the vertex angle of each prism is 90 degrees.

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

By arranging the auxiliary diffusion member, luminance unevenness can be suppressed and the thickness of the frame can be reduced.

In the above frame, a plurality of discharge lamps are arranged in parallel in the frame, and the arrangement interval of the discharge lamps is P [mm], and the distance between the tube axis of the discharge lamp and the front panel is d [mm], When the distance between the tube axis of the discharge lamp and the bottom surface of the frame is f [mm] and the luminous intensity in the thickness direction of the frame of the discharge lamp is r1 [mm], 0.10 ≦ (d + f ) / P <0.40, and satisfies the relationship of 1.7 <(d + f) / r1 <4.

By disposing the discharge lamps in the frame so as to satisfy this condition, it is possible to reduce the required number of discharge lamps while suppressing luminance unevenness.

Here, the discharge lamp preferably has a glass bulb having a flat cross section perpendicular to the tube axis, and is arranged such that the long inner diameter of the flat shape is parallel to the bottom surface of the frame.

In the above configuration, since the glass bulb has a flat shape, the backlight unit can be thinned by arranging a lamp inner diameter of the glass bulb in the thickness direction of the backlight unit. In addition, in this specification, the "flat shape" means that the glass tube of the cross section was crushed up and down, the inner diameter of the up-down direction was made into the short inner diameter, and the inner diameter of the left-right direction was made into the long inner diameter, and two flat parts which oppose a contour are mentioned. In addition to the shape including the curved portion connecting the two and these, it is also to include an elliptical shape in which the entire outline is represented by a curve.

The display device of the present invention is characterized by including any one of the above lighting devices as a light source.

Thereby, since the illumination device with little brightness unevenness mentioned above is provided as a light source, the display device with which the luminance distribution of the light radiate | emitted from the display surface was uniform can be provided.

1 is a view showing a liquid crystal display device of the present invention, a part cut in order to see the inside.

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

FIG. 3 is a view seen along the line A-A in FIG. 2.

4 is an enlarged cross-sectional view of the backlight unit 5 for explaining the light refraction sheet 13.

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

6 is a graph illustrating luminance distribution characteristics of a backlight unit.

Fig. 7 is a diagram showing the configuration of the hot cathode discharge lamp 20 of the present embodiment, Fig. 7 (a) is a plan sectional view, and Fig. 7 (b) is a cross sectional view when cut at the section B-B.

8 is a diagram illustrating a configuration of a backlight unit of a modification.

9 is a cross sectional view of a thermal cathode discharge lamp of a modification.

<Description of the code>

1 LCD

3 LCD screen unit

5 backlight unit

10 frames

11 inside

12 Auxiliary Reflector

13 Optical Refractive Sheet

14 diffuser plate

15 Diffusion Sheet

16 Lens Sheet

18 Front Panel

17 polarizing sheet

19 Auxiliary Diffusion Sheet

20 heat cathode discharge lamp

22 Glass Bulb

14 protective layer

26 phosphor layer

Hereinafter, a backlight unit and a liquid crystal display device according to an exemplary 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 of the present embodiment will be described with reference to FIG. 1. 1 is a view showing a liquid crystal display device of the present invention, a part cut in order to see the inside.

The liquid crystal display device 1 is, for example, a liquid crystal color television, and the liquid crystal display unit 3 and the backlight unit 5 are built in the main body 4. The liquid crystal display unit 3 includes, for example, a color filter substrate, a liquid crystal, a TFT substrate, a driving module and the like (not shown), and displays a color image on the basis of an image signal from the outside of the liquid crystal display unit 3. The screen 6 of the unit 3 is displayed.

<Configuration of the backlight unit>

The configuration of the backlight unit of this embodiment will be described with reference to FIG. 2. 2 is a schematic perspective view showing the configuration of a backlight unit 5 for a liquid crystal display with an aspect ratio of 16: 9 of the present embodiment. In the same 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 includes a plurality of hot cathode discharge lamps (hereinafter referred to as "lamps") 20, and a frame 10 having openings and storing these lamps 20. And a front panel 18 covering the opening of the frame 10.

The frame 10 is formed of, for example, an aluminum sheet metal to form a box having an opening, and has a polyester sheet having a white diffuse reflection characteristic on its inner surface 11 (in this embodiment, Toray E60L). ) Is attached.

The lamps 20 have a straight tube shape. In the present embodiment, four lamps 20 are arranged in the frame 10 in a direct manner and are electrically connected in parallel. The lamp 20 is constant current controlled by a lighting circuit (not shown). In addition, the structure of the lamp 20 is mentioned later.

In the frame 10 between the lamps 20, an auxiliary reflector 12 having a triangular prism shape is arranged. The auxiliary reflection plate 12 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 efficiently.

The opening of the frame 10 is covered with a light transmissive front panel 18 formed by stacking a light refracting sheet 13, a diffusion plate 14, a diffusion sheet 15, a lens sheet 16, and a polarizing sheet 17. It is sealed to prevent foreign matter such as dust or dust from entering the inside.

The function of the optical refraction sheet 13 in the front panel 18 will be described later in detail. The diffusion plate 14 and the diffusion sheet 15 diffuse light transmitted through the light refraction sheet 13. The lens sheet 16 collects the light transmitted through the diffusion plate 14 and the diffusion sheet 15 and deflects the light toward the normal line direction of the lens sheet 16. It is comprised so that the front may be irradiated uniformly over the whole surface (light emitting surface) of the panel 18.

Next, the arrangement position of the lamp 20 in the frame 10 will be described with reference to FIG. 3. FIG. 3 is a view seen along the line A-A in FIG. 2. The light refraction sheet 13 has a triangular prism row T, but the triangular vertices of the prism rows are arranged in contact with the diffusion plate 14, and the light refraction sheet 13 and the diffusion plate 14 are arranged. An air layer 19 is formed in the gap between them. In addition, in FIG. 3, the tube axis direction of the lamp 20 is made into the X-axis, the axis | shaft perpendicular to the said X-axis and parallel to the front panel 18 is made into the Y-axis, the axis perpendicular | vertical to an X-axis, and a Y-axis is Z-axis.

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

The lamp 20 is arranged at a position such that the coil axis of the electrode coil 31 is parallel to the bottom surface of the frame 10 and the distance from the front panel 18 is d [mm]. At this time, the distance between the coil shaft of the electrode coil 31 and the bottom surface of the frame 10 is f [mm]. In the lamp 20 arranged in this manner, the luminous diameter r1 [mm] in the thickness direction of the frame 10 is the inner diameter, and the luminous diameter r2 [mm] in the direction parallel to the bottom surface is the long inner diameter. to be.

Where the distances P, d, f are

0.10 ≤ (d + f) / P <0.40

It is most desirable to satisfy the relationship of. If (d + f) / P is less than 0.1, it is because luminance unevenness cannot be eliminated even when the optical refraction sheet 13 is arranged as in the present embodiment. If (d + f) / P is 0.4 or more, This is because the effect of reducing the number of lamps 20 does not occur.

Also, 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

It is appropriate to satisfy the relationship.

This equation is an empirical equation obtained by actually testing and evaluating a backlight unit having a thickness d + f of 20 to 60 [mm] using a lamp having a luminous diameter r1 of 10 [mm]. For lamps with different r1 values,

1.7 <(d + f) / r1 <4

It is desirable to satisfy the relationship. When (d + f) / r1 is 1.7 or less, the light emitting surface of the lamp and the optical refraction sheet 13 are too close to each other, and thus the function of the optical refraction sheet 13 cannot be sufficiently exhibited. When (d + f) / r1 is 4 or more, high uniformity can be obtained without necessarily arranging the optical refraction sheet 13.

Next, the optical refraction sheet 13 will be described with reference to FIG. 4. 4 is an enlarged cross-sectional view of the backlight unit 5 for explaining the light refraction sheet 13. In FIG. 4, only the light refracting sheet 13 is shown in the front panel 18, and other illustrations of the diffusion plate 14 and the lens sheet 16 are omitted.

The optical refraction sheet 13 has a triangular prism array T having a structure in which a plurality of triangular prisms 13b of an acrylic resin are bonded to a flat plate layer 13a of a polyester resin. The optical refraction sheet 13 is disposed such that the longitudinal direction of the triangular prism rows T is substantially parallel to the tube axis direction of the lamp 20.

Light incident on the optical refraction sheet 13 at an incident angle θ1 is emitted toward the diffusion plate 14 at an exit angle θ2 through refraction at the polyester resin layer 13a and the acrylic resin layer 13b. The incident light is incident on the diffusion plate 14 at the incident angle θ2.

By the earnest research of the present inventors, the following knowledge regarding the light-diffusion function of the diffusion plate 14 was obtained.

Conventionally, the incidence angle of light incident on the diffusion plate 14 is varied. In the area away from the lamp 20 which is a light source, the light emitted from the lamp 20 is incident on the diffusion plate 14 at a large incident angle. The diffusion plate 14 has a light diffusing function, but the intensity of the emitted light is highly dependent on the incident angle of the light. That is, even if light incident on the diffuser plate 14 at a large incident angle is diffused by the light diffusing function, the light emitted from the diffuser plate 14 also emits a lot of light having a large exit angle depending on the incident angle. . Light having a large exit angle is hardly condensed by the light condensing function of the lens sheet 16, and thus, it is difficult to contribute to the brightness of the backlight unit 5.

In the present embodiment, the light refracting sheet 13 can reduce the incident angle θ2 of light incident on the diffuser plate 14 particularly in the region away from the lamp 20. As a result, the emission angle of light diffused and emitted by the diffusion function of the diffusion plate 14 is reduced. Accordingly, the emitted light is condensed well by the condensing function of the lens sheet 16, thereby contributing to increasing the luminance of the area away from the lamp 20.

As described above, according to the configuration of the present embodiment, since the light stronger than the conventional light is emitted in the area away from the lamp 20, the luminance unevenness of the emitted light of the backlight unit 5 which has occurred conventionally can be improved.

Next, the optical refraction sheet 13 will be described with reference to FIG. 5. 5 is a cross-sectional view of the backlight unit for explaining the function of the optical refraction sheet 13. In FIG. 5, only the light refraction sheet 13 is shown in the front panel 18, and other illustrations of the diffusion plate 14 and the lens sheet 16 are omitted.

The light L1 emitted to the area of the lamp 20 and incident on the optical refraction sheet 13 at a small incident angle θα1 passes through the vertex angle of the triangular prism column T at the refraction angle θβ1, and at the apex of the triangular prism, It is emitted perpendicularly to the main plane of 13). When the refractive index of air is nα and the refractive index of the polyester resin layer 13a of the optical refraction sheet 13 is nβ, the incident angle θα1 and the refractive angle θβ1 satisfy Snell's law. That is, the incident angle θα1, the refractive angle θβ1, the refractive index nα and the refractive index nβ are

nαsin (θα1) = nβsin (θβ1)

I'm satisfied with the relationship.

On the other hand, the light L2 emitted to the region near the lamp 20 and incident on the optical refraction sheet 13 at the incident angle θα2 is emitted from the polyester resin layer 13a at the refractive angle θβ2, and then the acrylic resin layer constituting the prism. Since 13b is triangular, it totally reflects between the acrylic resin layer 13b and the air layer 19. The light reflected from the inclined surface of the triangular prism is emitted toward the bottom of the frame 10. The reflected light is reflected by the inner surface 11 of the frame 10, the auxiliary reflecting plate 12, the glass bulb of the lamp 20, and the like, and is re-incident on the optical refraction sheet 13 to be effectively used.

Light emitted to an area away from the arrangement position of the lamp 20, that is, light L3 and L4 incident at a large incident angles θα3 and θα4 with respect to the optical refraction sheet 13, enters the optical refraction sheet 13 and is Snell's law. The light is refracted accordingly and emitted as parallel light which is substantially perpendicular to the main surface of the diffusion plate 14 through the vertex angle of the triangular prism.

That is, by arranging the light refraction sheet 13 as described above, it has the same effect as if light is emitted from a region to which direct light is strongly irradiated.

That is, by arranging the light refraction sheet 13 between the lamp 20 and the diffusion plate 14, the light emitted from the lamp 20 passes through the light refraction sheet 13 to enter the diffusion plate 14. The light becomes uniform at the previous stage, and then the light passing through the diffusion plate 14 and the lens sheet and exiting from the front panel 18 also becomes uniform light without raising or lowering the local luminance. As described above, according to the present embodiment, even when the number of lamps 20 as the light source is small, transmission of direct light is suppressed, and a part of the reduced light is emitted from an area in which the direct light has not been emitted. It is possible to improve the luminance unevenness of the backlight unit.

<Effect>

Next, the effect of the backlight unit of this embodiment will be described with reference to FIG. 6. 6 is a graph illustrating luminance distribution characteristics of a backlight unit. The graph shown by the solid line is the data of the backlight unit 5 (the embodiment) of this embodiment, and the graph shown by the dotted line is the data of the backlight unit of the conventional example (comparative example). The vertical axis of the graph is the front panel surface luminance (relative value) [%], and the vertical axis is the luminance measurement position [mm]. The position of 0 [mm] of the horizontal axis corresponds to the position of the lowermost part of the front panel 18, and the position of 400 [mm] corresponds to the position of the uppermost part of the front panel 18. FIG.

As shown in Fig. 6, in the comparative example, it was found that the front panel surface luminance was less than 40% in the region far from the lamp 20, and luminance unevenness occurred. In contrast, in the embodiment, the front panel surface luminance of about 90% is maintained even in a region far from the lamp 20. In the present embodiment, the luminance unevenness is significantly improved as compared with the comparative example.

[Configuration of Lamp 20]

Next, the structure of the lamp 20 is demonstrated. Fig. 7 is a diagram showing the configuration of a thermocathode discharge lamp (hereinafter sometimes referred to simply as a “lamp”) 20 according to the present embodiment. Fig. 7 (a) is a plan sectional view and Fig. 7 (b) is a BB. It is a cross-sectional view at the time of cutting in a cross section.

The lamp 20 has a straight tube-shaped glass bulb 22 and a pair of electrodes 30a and 30b disposed at both ends in the glass bulb 22.

The glass bulb 22 is made of barium strontium silicate glass (soft glass having a softening point of 675 ° C). As shown in Fig. 7B, the glass bulb 22 has an elliptical cross section perpendicular to the tube axis having a long inner diameter C1 and a short inner diameter C2. Since the glass bulb 22 has an elliptical shape in this manner, the inner diameter of the lamp bulb 20 is arranged in the thickness direction of the backlight unit 5, that is, the inner diameter of the glass bulb 22 is arranged. Can be made perpendicular to the front panel 18 so that the backlight unit 5 can be thinned.

In addition, an exhaust pipe 28 is sealed to one end (left end in the drawing) of the glass bulb 22. The exhaust pipe 28 is used to exhaust the glass bulb 22 or to seal the rare gas, and is sealed after the exhaust and the sealing. The cold spot control becomes easy by providing the exhaust pipe 28 at one end rather than at both ends of the glass bulb 22. In other words, if it is installed at both ends, it is impossible to know which cold spot point becomes.

The electrodes 30a and 30b include electrode coils 31a and 31b wound around the trip coil 6.5 times, a pair of lead wires 32a, 32b, 33a and 33b supporting the electrode coils 31a and 31b, and It consists of the bead glass 34a, 34b which supports the lead wires 32a, 32b, 33a, 33b. The electrode coils 31a and 31b are, for example, made of tungsten, and are coated with oxides of strontium, calcium, and barium with an emitter.

On the inner surface of the glass bulb 22, a protective film 24 made of alumina is formed. The phosphor layer 26 is laminated on the protective film 24. Phosphors in the phosphor layer 26 include rare earths that emit red (Y ₂ O ₃ : Eu), green (LaPO ₄ : Ce, Tb ₃ ), and blue (BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn). A mixture of phosphors is used.

In the glass bulb 22, 5 mg of mercury 21 and argon (Ar) at a pressure of 500 Pa at normal temperature are sealed with a rare gas for buffering.

The mercury 21 encapsulated in the glass bulb 22 may be encapsulated in the form of amalgam such as zinc mercury, tin mercury, bismuth, indium mercury, etc. in addition to the mercury alone.

Here, specifications, such as each dimension of the lamp 20 at the time of using for a 45-inch liquid crystal display backlight unit, are demonstrated.

The long inner diameter C1 of the glass bulb 22 is 17 mm, the short inner diameter C2 is 10 mm, the full length L ₀ is 1010 mm, the distance Le between electrodes is 950 mm, and the tube wall load We is 0.05 W / cm 2. In addition, the tube wall load is a value obtained by dividing the lamp power by the internal surface area of the portion corresponding to the distance Le between the electrodes in the glass bulb 22.

Since the glass bulb has a flat shape as described above, the thickness of the backlight unit 5 can be reduced by arranging the inner cathode diameter of the glass bulb in the thickness direction of the backlight unit 5.

In addition, if the distance from the lamp 20 in the frame 10 of the backlight unit 5 to the liquid crystal panel is equal to the distance between the lamps 20 arranged in the frame 10 of the backlight unit 5, the liquid crystal display is the same. It is known that the luminance nonuniformity of can be suppressed. In this embodiment, since the shape of the glass bulb 22 is elliptical, 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. In connection with this, the luminance unevenness is suppressed even if the distance between the lamps of the lamps 20 arranged in the frame 10 of the backlight unit 5 is increased to the same size as the distance from the lamps 20 to the liquid crystal panel. The distance between the lamps of the lamps 20 arranged in the frame 10 can be increased, and the number of lamps 20 required as the light source can be reduced. As a result, the number of parts required for the backlight unit 5 can be reduced, thereby contributing to the cost reduction of the backlight unit 5.

In addition, although the structure which arrange | positioned four lamps 20 is demonstrated in FIG. 2, the number of lamps 20 arrange | positioned in the frame 10 of the backlight unit 5 is suitable according to the screen size of a liquid crystal display device. It may change.

<Variation example>

As mentioned above, although this invention was demonstrated based on the Example, the content of this invention is not limited to the specific example demonstrated in the said Example, Of course, For example, the following modified examples can be considered.

(1) Although the structure in which the optical refraction sheet 13 has the triangular prism rows T has been described above, the present invention is not limited thereto, and each prism of the prism rows may be trapezoidal, polygonal, or semicircular. The prism rows need not all have the same shape. For example, each prism is a triangle in the region near the arrangement position of the thermocathode discharge lamp, and the prism is a semicircle in the region away from the thermocathode discharge lamp. The configuration may be done.

(2) Although the structure in which the optical refraction sheet 13 has a prism row has been described above, the prism row may not necessarily be provided. For example, the optical refractive sheet 13 may have a refractive index distribution having a high refractive index at a position corresponding to the lamp 20 and gradually decreasing the refractive index as it moves from the position to a region away from the discharge lamp. . As a result, the light radiated to the region near the lamp 20 can suppress the transmittance, and can improve the transmittance of the light radiated to the area away from the lamp 20, and the backlight is used even when the number of the lamps 20 as the light source is small. It is possible to improve the luminance unevenness of the unit 5.

(3) Although the structure in which the optical refraction sheet 13 is in contact with the diffusion plate 14 has been described above, the configuration is not limited thereto. The light refracting sheet 13 only needs to be disposed between the lamp 20 and the diffusing plate 14, that is, the light refracting sheet 13 is separated from the diffusing plate 14 without being in surface contact with the diffusing plate 14. It may be a constitution. However, in order to reduce the thickness of the apparatus by making the distance d shown in FIG. 3 small, it is most preferable that the light refracting sheet 13 is arranged so that the vertices of the prism are in contact with the diffusion plate 14.

(4) In the above, the case where the diffusion plate 14, the diffusion sheet 15, and the lens sheet 16 are each independently independent has been described. For example, instead of these, after the incident light is diffused, One diffusion / condensing sheet having a function of condensing may be used.

(5) In order to reduce the thickness of the device, if the distance d between the lamp 20 and the optical refraction sheet 13 in FIG. 3 is reduced, the area in which the direct light of the lamp 20 is emitted is narrowed, whereby luminance unevenness is caused. This is encouraged. Therefore, by setting it as the structure of the following modifications, it can suppress that a luminance nonuniformity generate | occur | produces even if a device becomes thinner.

8 is a diagram illustrating a configuration of a backlight unit of a modification. As shown in FIG. 8, the auxiliary diffusion sheet 19 may be disposed in the space between the lamp 20 and the front panel 18 of the lamp 20. Since the direct light intensity of the lamp 20 can be lowered by this, distance d can be made small and thickness of an apparatus can be thinned.

(6) In the above, the glass bulb of the lamp 20 has been described that the cross section perpendicular to the tube axis is elliptical, as shown in Fig. 7 (b), but the present invention is not limited thereto. Any shape may be used as long as it has a shape. 9 is a cross-sectional view of a thermal cathode discharge lamp of a modification. For example, it may be made into a flat shape as shown in Fig. 9 (a) or may have a rectangular shape as shown in Fig. 9 (b). Also in these cases, since the inside diameter C1 is large with respect to the magnitude | size of the inside diameter C2, the length of the electrode coil in the axial direction can be enlarged. In addition, the device can be thinned by arranging the glass bulb of the lamp 20 so that the inner diameter C2 is perpendicular to the surface of the liquid crystal panel.

(7) Although the glass bulb of the lamp 20 has been described as having a linear shape, the present invention is not limited thereto. For example, the glass bulb of the lamp 20 may have a U shape and a C shape. Etc., you may have another shape.

In addition, the glass bulb of the lamp 20 may have an annular shape, and at this time, the prism rows of the optical refraction sheet 13 need to be arranged in an annular shape parallel to the axis of the glass bulb when viewed in plan view. There is. Also in this case, luminance unevenness of the backlight unit can be reduced.

(8) In the above, argon and krypton are encapsulated with a buffer rare gas, but in addition, neon or xenon may be encapsulated. Since xenon has a large atomic weight, scattering of the emitter applied to the electrode coil can be suppressed, and the lifetime can be further extended by encapsulation of xenon.

(9) Although the protective film 24 was formed in the inner surface of the glass bulb 22 in the above, the protective film 24 does not need to be formed.

(10) In the above, the case where the hot cathode discharge lamp is used as the light source of the backlight unit has been described, but the present invention is not limited thereto. Instead of the hot cathode discharge lamp, a cold cathode discharge lamp or other discharge lamps may be used. You may use it as a light source. In addition, a linear light source in which LEDs, light bulbs, and the like are arranged in a line shape instead of a general discharge lamp may be used. Also in these cases, according to the present invention, luminance unevenness can be improved even with a small number of lamps by the same mechanism as described above.

(11) Although the backlight unit has been described as an example of the lighting device, the present invention is not limited thereto. For example, the general lighting unit may include a frame and a thermal cathode discharge lamp of the present embodiment disposed in the frame.

(12) Although the liquid crystal display device has been described as an example of the display device, the present invention is not limited thereto, and the display device includes, for example, a sign device including a frame and a thermal cathode discharge lamp of the present embodiment disposed in the frame. It may be.

The present invention can be widely applied to lighting devices and display devices. In addition, the present invention can provide an illumination device and a display device in which the luminance unevenness is suppressed even when the number of lamps of the light source is small, so that the industrial use value is very high.

Claims (11)

An illumination device comprising a frame having an opening, a discharge lamp disposed in the frame, and a front panel covering the opening of the frame. When the axis of the tube 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, the axis perpendicular to the X axis and the Y axis, the Z axis, The front panel, An optical refraction member which refracts and emits light emitted from the discharge lamp; And a diffusion / condensing member for diffusing and condensing the light emitted from the light refraction member, The light refraction member, When the incident angle of light in the Y-Z plane is θ1 and the exit angle is θ2, and θ1> 0, θ1> θ2 Illuminating apparatus characterized in that the incident light is refracted to satisfy the relationship of the emitted. The method according to claim 1, The light refracting member suppresses the transmittance that the incident angle with respect to the member surface among the light emitted by the discharge lamp is small, and gradually increases the transmittance of light as the incident angle increases, thereby adjusting the transmittance of light emitted from the discharge lamp. Illuminating apparatus, characterized in that. The method according to claim 1 or 2, The light refracting member has a prism row, And the prism rows are arranged in parallel to the tube axis of the discharge lamp. The method according to claim 3, And the prism rows are formed in the entirety of the light refracting member that faces the diffusion / condensing member. The method according to claim 3 or 4, Each prism of the prism row has a substantially triangular cross-sectional shape perpendicular to the tube axis of the discharge lamp, and the vertex angle of each prism is 80 ° or more and 120 ° or less, and the vertex angle of each prism is the diffusion and A lighting device facing the light collecting member. The method according to claim 5, Illumination device, characterized in that the angle of the vertex angle of each prism is 90 °. The method according to any one of claims 1 to 6, And an auxiliary diffusion member configured to diffuse light emitted by the discharge lamp between the discharge lamp and the light refraction member. The method according to any one of claims 1 to 7, A plurality of discharge lamps are arranged in parallel in the frame, The spacing of the discharge lamp is P [mm], the distance between the tube axis of the discharge lamp and the front panel is d [mm], and the distance between the tube axis of the discharge lamp and the bottom of the frame is f [mm]. When the light emission diameter in the thickness direction of the frame of the discharge lamp is r1 [mm], 0.10 ≦ (d + f) / P <0.40, Also, 1.7 <(d + f) / r1 <4 Lighting device characterized in that to satisfy the relationship. The method according to any one of claims 1 to 8, The discharge lamp has a glass bulb having a flat cross section perpendicular to the tube axis, A flat device having a long internal diameter arranged parallel to the underside of the frame. An illumination device comprising a frame having an opening, a discharge lamp disposed in the frame, and a front panel covering the opening of the frame. The front panel, An optical refraction member which refracts and emits light emitted from the discharge lamp; And a diffusion / condensing member for diffusing and condensing the light emitted from the light refraction member, The light refraction member, When the angle of incidence of light on the plane parallel to the main surface of the front panel is θ1 and the emission angle is θ2, and θ1> 0, θ1> θ2 Illuminating apparatus characterized in that the incident light is refracted to satisfy the relationship of the emitted. A display device comprising the illuminating device according to any one of claims 1 to 10 as a light source.

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