JP2001266605A - Lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system of a high light utilization efficiency. SOLUTION: This luminaire is provided with plural ultraviolet ray lamps 2 emitting ultraviolet rays 11, a luminous plate emitting visible rays 12 when irradiated with ultraviolet rays 11, a filter 4 reflecting ultraviolet rays and transmitting visible rays 12 and absorbing or reflecting infrared rays, and a diffusing plate 5 to make unevenness of light source from plural ultraviolet lamps 2 inconspicuous. A reflection plate 7 reflecting the ultraviolet rays emitted from the ultraviolet lamps 2 and visible rays to a liquid crystal panel 6 is provided at a location of an opposite side of the liquid crystal panel 6 across the ultraviolet lamps 2 and the luminous plate 3 is formed on the reflection plate 7. Accordingly, most of the ultraviolet emitted from the ultraviolet lamps 2 irradiate directly or, after reflected by a filter 4, the luminous plate 3, and the ultraviolet rays 11 are efficiently converted to visible rays 12 at the luminous plate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device suitable as, for example, a backlight for a liquid crystal display.

[0002]

2. Description of the Related Art In recent years, thin television receivers and displays for computer devices have become widespread in consideration of installation space and portability. As these thin displays, for example, liquid crystal displays using liquid crystal panels are well known.

By the way, a transmissive liquid crystal display is
A backlight for irradiating the liquid crystal panel with light is required. For this reason, there are two types of liquid crystal displays: a type in which a backlight is arranged directly below a liquid crystal panel (hereinafter, referred to as a “direct type liquid crystal display”) and a type in which a backlight is arranged on the lower side of a liquid crystal panel (hereinafter, “ Edge-lit LCD ")
And can be broadly divided into

Hereinafter, the configuration of a backlight provided in a conventional liquid crystal display will be described with reference to FIGS. FIG. 8 is a perspective view for explaining the structure of a backlight provided in a conventional direct type liquid crystal display, and FIG. 9 is a sectional view thereof. As shown in FIGS. 8 and 9, the backlight of the direct-type liquid crystal display 100 includes a plurality of fluorescent tubes 101 having a rod shape,
A reflecting plate 102 that reflects light rays (mainly visible light rays) 105 emitted from the fluorescent tubes 101 toward the liquid crystal panel 104 (light emitting side), and a plurality of fluorescent tubes 101 that are arranged in front of the liquid crystal panel 104. It is composed of a diffusion plate 103 for making the luminance unevenness of the light source inconspicuous.

Here, FIG. 10 shows a structure of a hot cathode tube which is well known as an example of a fluorescent tube. As shown in FIG. 10, the fluorescent tube 101 is provided outside the glass tube 115 with a pair of base pins 111 provided on both left and right ends thereof. When a voltage is applied to the base pins 111, the electrode 112 in the glass tube 115 is heated, and thermoelectrons are emitted from the electrode 112. Then, a high voltage of AC or DC is applied to the base pin 111 to discharge between the electrodes 112 and 112. Then, the discharge excites the mercury vapor 113 sealed in the glass tube 115 to generate ultraviolet light in the glass tube, and further causes the ultraviolet light to be applied to the phosphor 114 applied to the inner surface of the glass tube 115. Excitation produces visible light. Then, this visible light is emitted to the outside through the glass tube 115.

Accordingly, in the direct type liquid crystal display shown in FIG.
Is directly or reflected by the reflector 102 and diffused by the diffuser 103
Is irradiated. At this time, the diffusion plate 103 is
The visible light 105 that reaches the light source has unevenness because the fluorescent tubes 101 are arranged at spatially discrete positions. However, since the visible light 105 is diffused by the diffusion plate 103, the liquid crystal panel The luminous flux applied to 104 is made uniform.

FIG. 11 is a perspective view for explaining the structure of a backlight provided in a conventional edge light type liquid crystal display, and FIG. 12 is a sectional view thereof. The same portions as those of the direct type liquid crystal display shown in FIGS. 8 and 9 are denoted by the same reference numerals, and description thereof will be omitted.

In the backlight of the edge light type liquid crystal display 120 shown in FIGS. 11 and 12, one fluorescent tube 101 as a light source is arranged on a lower side surface of a liquid crystal panel 104. In this case, a reflector 121 that reflects the visible light 105 emitted from the fluorescent tube 101 to the lower side of the liquid crystal panel 104 and a light guide for guiding the visible light 105 from the fluorescent tube 101 to the entire liquid crystal panel 104 through the diffusion plate 103. The light body 122 and the reflection plate 102 that reflects light passing through the light guide 122 are provided.

In this case, the visible light 105 emitted from the fluorescent tube 101 enters the light guide 122 directly or after being reflected by the reflector 121 as shown in FIG. At this time, a part of the light beam incident on the light guide 122 is
Light emitted from the upper interface of the light guide 22 and having an incident angle (θ) from the light guide 122 to the upper space equal to or larger than the critical angle is reflected at the interface.

The reflected visible light 105 is totally reflected by the reflector 102 on the lower surface side of the light guide 122, travels again toward the upper surface, and a part of the light is emitted from the upper interface of the light guide 122. . As described above, the visible light 105 is repeatedly reflected in the light guide 122, so that light emitted from the upper portion of the light guide 122 irradiates the entire diffusion plate 103. Also in this case, the light guide 122 is
In this case, the visible light 105 irradiates the liquid crystal panel 104 in the same manner as described above. However, as described above, the luminous flux irradiated on the liquid crystal panel 104 is made uniform by diffusing the light by the diffusion plate 103.

[0011]

However, in the direct type liquid crystal display 100 or the edge light type liquid crystal display as described above, the fluorescent tube 1 is used as a light source.
Since 01 is used, there is a problem in that the illuminance of the visible light 105 applied to the liquid crystal panel 104 is reduced due to factors described later, and as a result, the brightness of the image projected on the liquid crystal panel 104 is reduced.

The above-mentioned problems will be described by taking a direct type liquid crystal display as an example. FIG. 13 is an enlarged view of a part of the sectional view of the direct type liquid crystal display shown in FIG. 9 above. As described above, the fluorescent tube 101 is
As shown in FIG. 13, the structure is such that ultraviolet rays 116 generated inside the glass tube 115 excite the phosphor 114 and emit the visible light 105 to the outside. In such a structure, the light is attenuated when passing through the phosphor 114 coated on the inner surface of the glass tube 115, and the emitted visible light 105 is lost.

Here, the cause of the loss of the visible light 105 will be specifically described with reference to an enlarged view of the glass tube 115 and the phosphor 114 of the fluorescent tube 101 shown in FIG. The arrow A shown in FIG. 14 indicates the observation direction (light emission direction) of the visible light 105 emitted from the fluorescent tube 101.
Is shown. The phosphor 114 applied to the glass tube 115 has a property that it is difficult to transmit the ultraviolet ray 116 shown by the dotted line and the visible light 105 shown by the solid line. Therefore, the ultraviolet rays 116 generated inside the fluorescent tube 101 and the visible light rays 105 generated by the ultraviolet rays 116
4 decay inside.

Therefore, first, the attenuation of the ultraviolet rays 116 generated in the phosphor 114 will be described. First, assuming that the film thickness of the phosphor 114 is limited (the thickness is indicated by L in the figure), the ultraviolet rays 116 generated inside the fluorescent tube 101 are irradiated on the phosphor 114. In this case, all of the ultraviolet rays 116 The visible light 105 converted by the phosphor 114 without penetrating the phosphor 114 is large at the position m on the surface side (the inner wall side) of the phosphor 114 and is reduced at the position k on the deep surface side (the glass tube 115 side). .

Here, for example, the phosphor 114 shown in FIG.
The amount of ultraviolet light of the ultraviolet light 116 applied to the position m of the fluorescent material 114 and the amount of ultraviolet light U attenuated by the fluorescent material 114
4, the loss of the ultraviolet rays 116 in the phosphor 114 having the film thickness L is reduced by 80%, for example.
And

In this case, the amount of ultraviolet light at the position k of the phosphor 114 is 0.2 × U, and the amount of ultraviolet light at the intermediate position i is 0.6 × U. Accordingly, the amount of visible light at each position m, i, k of the phosphor 114 is represented by B1, B
2, B3, the relation between B2 and B1 and the relation between B3 and B1 are as follows: B2 = 0.6 × B1 (Equation 1) B3 = 0.2 × B1 (Equation 2) Can be shown.

The visible light 105 emitted at each of the positions m, i, and k of the phosphor 114 is also attenuated when passing through the phosphor 114. For example, the amount of attenuation of the visible light Like UV 116,
The thickness is assumed to be proportional to the thickness of the phosphor 114, for example, the thickness L
, The loss of the visible light 105 is set to 80% as in the case of the ultraviolet light 116. Further, assuming that the transmittance of the visible light 105 of the glass tube 115 is 100%, the luminous flux (visible light amount) B observed from the observation direction A is: B = (B1 × 0.2) + (B2 × 0.6 ) + (B3 × 1.0) (Equation 3)

Therefore, the above (Equation 1) and (Equation 2) are substituted into (Equation 3), and the position on the outer surface side of the phosphor 114 with respect to the amount of visible light B1 generated at the position m on the inner wall surface side of the phosphor 114 The luminous flux B observed at k is as follows: B = 0.76 × B 1 (Equation 4). That is, the visible light 1 emitted from the fluorescent tube 101
It can be seen that the luminous flux B of 05 is 76% of the amount of visible light B1 generated on the surface of the phosphor 114 applied to the fluorescent tube 101.

When the fluorescent tube 101 is used as the light source of the direct type liquid crystal display as described above, about 24% of the amount of visible light B1 generated on the surface of the phosphor 114 due to light transmission loss due to the thickness L of the phosphor 114. Is attenuated, and as a result, the brightness of the image projected on the liquid crystal panel 104 is reduced.

In particular, the conventional direct type liquid crystal display 10
At 0, the visible light 105 emitted from the fluorescent tube 101 is applied to the diffuser 103 directly or via the reflector 102 as shown in FIG. Is again irradiated on the diffusion plate 103 through the fluorescent tube 101. At this time, the light passes through the fluorescent tube 101 again and passes through the diffusion plate 103.
Is attenuated by the phosphor 114 applied to the fluorescent tube 101, and is directly emitted from the fluorescent tube 101.
It becomes smaller than the luminous flux applied to the diffusion plate 103. As a result, there is also a problem that unevenness occurs in the light beam irradiated on the diffusion plate 103 and unevenness in luminance occurs on the surface of the liquid crystal panel 104.

Therefore, the conventional direct type liquid crystal display 1
In 00, in order to reduce the uneven brightness in the liquid crystal panel 104, for example, the diffusion rate of the diffusion plate 103 is increased. However, when the diffusion rate of the diffusion plate 103 is increased, Rate,
As a result, there arises a problem that the luminance on the liquid crystal panel 104 is greatly reduced.

[0022]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a light source that emits light containing at least ultraviolet light, and that emits light by converting ultraviolet light into visible light. A light-emitting unit, at least a filter unit that transmits visible light and reflects ultraviolet light, and is disposed to face the filter unit and the light-emitting unit so as to contain ultraviolet light emitted from the light source; It was arranged to be on the emission side.

Further, a reflecting means for reflecting ultraviolet light and visible light is provided on the surface of the light emitting means opposite to the light source.

According to the present invention, since the filter means and the light emitting means are opposed to each other with the light source interposed therebetween so as to contain the ultraviolet light emitted from the light source, most of the ultraviolet light is reflected directly or by the filter means. Since the light is emitted to the light emitting means, the ultraviolet light can be efficiently converted into visible light by the light emitting means. Further, by disposing the filter means on the surface of the light emitting means opposite to the light source, visible light can be more efficiently emitted from the light emitting means.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the lighting device according to the present invention will be described below. FIGS. 1 and 2 are views for explaining the structure of a backlight of a direct type liquid crystal display according to an embodiment of the present invention. FIG. 1 is a perspective view of FIG.
Is a sectional view thereof. The direct type liquid crystal display 1 shown in FIGS. 1 and 2 has at least ultraviolet rays 11 indicated by dotted lines.
A plurality of discharge lamps (ultraviolet lamps) 2 that emit light including: a light emitting plate 3 that emits visible light 12 when irradiated with ultraviolet light 11;
And a diffuser plate 5 on the upper surface side (light emission side) of the filter 4 for preventing unevenness of the light source by the plurality of ultraviolet lamps 2 from being noticeable. Are provided. further,
The light emitting plate 3 is disposed at a position (lower surface side) opposite to the liquid crystal panel 6 via the ultraviolet lamp 2, and a protective film 8 is coated on the light emitting plate 3. On the lower surface of the light emitting plate 3, a reflecting plate 7 for reflecting ultraviolet rays 11 and visible rays 12 is provided.

The ultraviolet lamp 2 has a rod shape, for example, like the fluorescent tube 101 described above. For example, when the ultraviolet lamp 2 is constituted by a hot cathode tube or a cold cathode tube,
Ultraviolet rays can be generated by sealing mercury vapor inside. In this case, the ultraviolet radiation in the spectrum of mercury generated by the discharge has the strongest resonance radiation at 253.7 nm. The glass tube (glass tube) for containing the mercury vapor is, for example, a wavelength region of the ultraviolet light 11 (100 nm to 380 nm) and a wavelength region of the visible light 12 in order to minimize the attenuation of the ultraviolet light 11 and the visible light 12. (400nm
(To 700 nm), for example, made of a material such as quartz glass.

The light emitting plate 3 converts ultraviolet light 11 emitted from the ultraviolet lamp 2 into visible light 12. For this reason, the light emitting plate 3 is formed of a fluorescent film that converts the ultraviolet light 11 into visible light 12. As the material of the phosphor, for example, trade name “NP-105: B (SrCaBa) ₅ (PO ₄ ) ₃ Cl: Eu”,
_{"NP-220: G (LaPO 4} : CeTb) ", "NP-340:
R (Y ₂ O ₃ : Eu) ”: manufactured by Nichia Chemical Co., for example, the blending ratio may be R: G: B = 33: 24: 44.

The protective film 8 coated on the surface of the light emitting plate 3 is a transparent member that transmits ultraviolet rays 11 and visible rays 12, for example. Specific examples of the material of the protective film 8 include, for example, SiO ₂ and MgO. However, the material is not limited as long as the ultraviolet light 11 and the visible light 12 can be transmitted. The reflection plate 7 formed below the light-emitting plate 3 is formed by coating or attaching a reflection member that reflects ultraviolet rays 11 and visible light rays 12, for example. As a material of the reflection plate 7, for example, silver deposition or the like can be considered. However, the material is not limited as long as the ultraviolet light 11 and the visible light 12 can be reflected.

As will be described later, the filter 4 includes
1 and a filter that transmits visible light 12. Further, it has an action of absorbing or reflecting infrared rays.

FIG. 5 shows an example of the characteristics of the filter 4. As shown in FIG. 5, the filter 4
It has characteristics such that light of 100 nm to 380 nm, which is one wavelength region, is almost completely cut off and reflected, and visible light 12 whose wavelength region is 400 nm or more passes. Accordingly, for example, 25
The ultraviolet light 11 of 3.7 nm is reflected by the filter 4 and irradiates the light emitting plate 3 to be converted into visible light 12 by the light emitting plate 3. The filter 4 can be constituted by, for example, an interference film filter using a multilayer thin film. However, the filter 4 is not limited as long as it has the above-described characteristics.

As described above, the backlight of the direct type liquid crystal display 1 according to the present embodiment uses the ultraviolet lamp 2 for emitting ultraviolet light instead of the fluorescent tube 101 which has been conventionally used as a light source. The light-emitting plate 3 for converting the ultraviolet light 11 emitted from 2 into visible light 12 is arranged on the lower surface of the ultraviolet lamp 2. The filter 4 that reflects at least the ultraviolet rays 11 and transmits the visible light rays 12 is arranged on the upper surface of the ultraviolet lamp 2. In other words, the filter 4 and the light emitting plate 3 are arranged opposite to each other with the ultraviolet lamp 2 interposed therebetween so that the ultraviolet light 11 emitted from the ultraviolet lamp 2 is contained and the filter 4 is on the emission side of the visible light 12.

In this case, as shown in FIG. 2, the ultraviolet light 11 emitted from the ultraviolet lamp 2 is irradiated directly or on the light emitting plate 3 after being reflected by the filter 4, and the visible light 12 is generated by the light emitting plate 3. . Then, only the visible light 12 passes through the filter 4 and is disposed on the light exit side.
Reach Further, the diffusion plate 5 is configured to make the luminous flux irradiated on the liquid crystal panel 6 uniform.

Here, the conversion of the ultraviolet rays 11 into visible rays 12 in the backlight shown in FIGS. 1 and 2 will be specifically described with reference to FIG. In the present embodiment, since the light emitting plate 3 is arranged on the lower surface side of the ultraviolet lamp 2 outside the ultraviolet lamp 2 serving as the light source, the observation direction A of the visible light 12, that is, the arrangement direction of the liquid crystal panel 6. The light emission direction is the same as the incident direction of the ultraviolet light 11 incident on the light emitting plate 3 unlike the above-described FIG. The light emitting plate 3
The phosphor is made of the same material as the phosphor 114 shown in FIG. 14, and has a property of hardly transmitting the ultraviolet rays 11 and the visible rays 12. Therefore, the ultraviolet rays 11 and the visible rays 12 are attenuated by the phosphor of the light emitting plate 3. Note that, for the sake of simplicity, it is assumed that the influence of the reflector 7 attached to the lower surface of the light emitting plate 3 is not considered here.

Here, the thickness of the phosphor of the light emitting plate 3 is L
And the ultraviolet rays 11 generated by the ultraviolet lamp 2
Also in this case, similarly to FIG. 14, the visible light 12 converted by the light emitting plate 3 because the ultraviolet rays 11 hardly penetrate into the phosphor of the light emitting plate 3, is also positioned at the position m on the surface side of the phosphor 114. And decreases at the position k on the deep surface side. Also, for example, the amount of ultraviolet light applied to the position m of the light emitting plate 3 is U, the amount of visible light emitted from the light emitting plate 3 is B, and the amount of ultraviolet light U attenuated by the light emitting plate 3 is the thickness of the light emitting plate 3 The loss of the ultraviolet rays 11 in the light emitting plate 3 having the film thickness L is assumed to be 80%, for example.

Also in this case, the amount of ultraviolet light at the position k of the light emitting plate 3 is 0.2 × U, and the amount of ultraviolet light at the intermediate position i of the film thickness L is 0.6 × U. Accordingly, the amount of visible light B at each position m, i, k of the light emitting plate 3 is represented by B1, B
Assuming that B2 and B3, the relationship between B2 and B1 and the relationship between B3 and B1 can be expressed by (Equation 1) and (Equation 2) described above.

The amount of visible light B emitted from the light emitting plate 3 is also attenuated when passing through the phosphor of the light emitting plate 3 as in FIG. 14, but in this embodiment, Since the incident direction of the ultraviolet rays 11 and the observation direction are the same, the luminous flux (visible light amount) B observed is: B = (B1 × 1.0) + (B2 × 0.6) + (B3 × 0. 2)... (Equation 5)

Therefore, by substituting the above (Equation 1) and (Equation 2) into (Equation 5), the visible light amount B1 at the position m point is compared with the visible light amount B1 generated at the position m of the light emitting plate 3.
B = 1.40 × B1 (Equation 6)

As described above, in the present embodiment, the light emitting plate 3 is disposed outside the ultraviolet lamp 2 and below the ultraviolet lamp 2 so that the emission direction of the visible light 12 generated by the light emitting plate 3 and the light emitting plate 3 By setting the incident direction of the ultraviolet rays 11 to be the same, the visible light B is generated from the light emitting plate 3 by 1.4 times the amount of visible light B1 generated on the surface of the light emitting plate 3. Therefore, according to the present embodiment, as apparent from a comparison between (Equation 6) and (Equation 4), about 1.
9 times the amount of visible light B is obtained.

Next, the effect of the amount B of visible light due to the reflection plate 7 provided on the lower surface of the light emitting plate 3 will be described with reference to FIG. Also in this case, as in FIG. 3, if the visible light amounts obtained at the respective positions m, i, and k of the light emitting plate 3 are B1, B2, and B3, respectively, the relationship between B2 and B1 and B3 and B1
Can be represented by the above (Equation 1) and (Equation 2).

The visible light amounts B1, B2, and B3 converted at the respective positions of the light emitting plate 3 pass through the inside of the light emitting plate 3, are reflected by the reflecting plate 7, and return to the observation position A again. Assuming that the amount of visible light to be observed is B11, B12, B13, B11 = 0.2 × (0.2B1) (Equation 7) B22 = 0.2 × (0.6 × 0.6B1) (Equation 8) B33 = 0.2 × (0.2B1) (Equation 9)

Therefore, the amount of visible light ΔB increased by the reflector 7 is as follows: ΔB = B11 + B22 + B33 = 0.2 × 0.76B1 (Equation 10) ΔB = 0.152 × B1 (Equation 11) Become. That is, by providing the reflecting plate 7 on the lower surface of the light emitting plate 3, the visible light amount B increases by ΔB.

Further, in the present embodiment, the ultraviolet lamp 2
By disposing a filter 4 that transmits the visible light 12 but reflects the ultraviolet light 11 between the diffuser 5 and the diffuser 5, the ultraviolet light 11 radiated to the light emitting plate 3 is increased. In this case, the amount of increase of the ultraviolet rays 11 is determined by the arrangement position of the ultraviolet lamps 2 and the like. However, for simplicity, 80% of the half of the ultraviolet rays 11 emitted from the ultraviolet lamps 2 reaches the filter 4, and This filter 4
It is assumed that the ultraviolet rays 11 are reflected at a reflectance of 90%, and that 80% of the reflected ultraviolet rays 11 reach the light emitting plate 3. Then, the increase amount ΔU of the ultraviolet light 11 irradiated to the light emitting plate 3 by disposing the filter 4 is expressed as follows: ΔU = 0.8 × 0.9 × 0.8 = 0.576 (Equation 12) . That is, by providing the filter 4, about 1.
Since the light emitting plate 3 can be irradiated with 576 times the ultraviolet rays 11, the visible light 1 generated in the light emitting plate 3 is correspondingly increased.
2, the visible light amount B can be increased.

As described above, in the direct type liquid crystal display 1 according to the present embodiment, the amount of visible light B is increased by disposing the light emitting plate 3 on the lower surface side outside the ultraviolet lamp 2, and the light emitting plate 3 The liquid crystal panel 6 is irradiated by three factors: an increase in the amount of visible light B due to the arrangement of the reflector 7 on the lower surface, and an increase in the amount of ultraviolet light U due to the arrangement of the filter 4 that reflects the ultraviolet light 11 on the light emission side. The amount of visible light B is increased.

Then, the total amount of visible light B obtained by combining these is as follows: B = (1.40 + 0.152) × 1.576 × B 1 Ｂ2.5B 1 (Equation 13) The amount of visible light B emitted from the backlight of the direct type liquid crystal display 1 is the amount of visible light B of the backlight of the conventional liquid crystal display.
(0.76B1) can be increased to about 3.7 times.

Note that the method of calculating the light amount in the present embodiment has been described for the sake of convenience only, and it is needless to say that it is necessary to perform the calculation strictly by using integration or the like.

In this embodiment, the ultraviolet lamp 2
Transmits ultraviolet light 11 and visible light 12, so that the ultraviolet light 11 reflected by the filter 4 and the visible light 12 generated from the light emitting plate 3 hardly attenuate when passing through the ultraviolet lamp 2. Therefore, the unevenness of the visible light 12 irradiated on the diffusion plate 5 is reduced, and the diffusion rate of the diffusion plate 5 can be reduced. As a result, the transmittance of the diffusion plate 5 increases, and the brightness of the image projected on the liquid crystal panel 6 can be improved.

Further, since the filter 4 reflects the ultraviolet rays 11, the ultraviolet rays 11 are not irradiated to the liquid crystal panel 6 via the diffusion plate 5, and the alignment film of the liquid crystal panel 6 is not damaged by the ultraviolet rays 11. There is also the advantage of not receiving it. Further, if a member capable of reflecting or absorbing infrared rays is used for the filter 4, the infrared rays do not reach the liquid crystal panel 6, so that the thermal stress on the liquid crystal panel 6 is also reduced.

Further, the present invention is not limited to the direct type liquid crystal display described above, but can be applied to, for example, an edge light type liquid crystal display. 6 and 7 are views for explaining the structure of the backlight of the edge light type liquid crystal display according to the second embodiment of the present invention. FIG. 6 is a perspective view and FIG. 7 is a sectional view. is there. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The liquid crystal display 2 shown in FIGS.
In the backlight of No. 0, one ultraviolet lamp 2 as a light source is arranged on the lower side surface of the liquid crystal panel 6. A light emitting plate 22 that emits visible light 12 when the ultraviolet light 11 is irradiated from the ultraviolet lamp 2, a filter 4 that reflects the ultraviolet light 11, transmits the visible light 12, and further absorbs or reflects infrared light. A light guide 24 and a reflector 23 for guiding the visible light 12 to the entire liquid crystal panel 6 through the diffuser 5 are provided. Also in this case, the filter 4 is arranged on the emission side of the visible light 12, and the light emitting plate 22 is arranged on the opposite side to the liquid crystal panel 6 via the ultraviolet lamp 2, and the ultraviolet light is A reflector 21 for reflecting the visible light 11 and the visible light 12 is provided.

Also in this case, as shown in FIG. 7, the ultraviolet light 11 emitted from the ultraviolet lamp 2 is irradiated directly or on the light emitting plate 22 after being reflected by the filter 4, and the visible light 12 is generated by the light emitting plate 22. I do. Then, only this visible light 12 passes through the filter 4 arranged on the light emission side and reaches the diffusion plate 5. Then, the liquid crystal panel 6 is
The light beam irradiated on the surface is made uniform. Therefore, the same effects as those of the direct type liquid crystal display shown in FIGS. 1 and 2 can be obtained. Further, when the edge-light type liquid crystal display is configured as described above, there is an advantage that the size of the filter 4 can be smaller than that of the direct type liquid crystal display.

In this embodiment, the direct type liquid crystal display and the edge light type liquid crystal display, which are typical backlight structures, have been described as examples. However, this is merely an example, and the present invention is not limited thereto. Needless to say, the present invention can be applied to a liquid crystal display having a backlight having another structure.

[0052]

As described above, in the lighting device of the present invention, since the filter means and the light emitting means are arranged opposite to each other with the light source interposed therebetween so as to contain the ultraviolet light emitted from the light source, almost all of the ultraviolet light is contained. Since the light is emitted to the light emitting means directly or after being reflected by the filter means, the ultraviolet light can be efficiently converted into visible light by the light emitting means. Therefore, when the present invention is applied to a backlight of a liquid crystal display, it is possible to improve the luminance of the liquid crystal display and to reduce power consumption accompanying the improvement in the luminance.

Further, if the filter means is provided on the surface of the light emitting means opposite to the light source, visible light can be emitted from the light emitting means more efficiently.
Further improvement in luminance and reduction in power consumption can be realized.

Further, since the ultraviolet rays are reflected (blocked) by the filter means and the ultraviolet rays are not emitted from the light emission side, for example, if the present invention is applied to a backlight of a liquid crystal display, the alignment surface of the liquid crystal panel may be reduced. There is also an advantage that the liquid crystal panel is not adversely affected without being irradiated with ultraviolet rays.

Further, by providing the filter means with a function of reflecting or absorbing infrared rays, the infrared rays are not irradiated to the liquid crystal panel, and the thermal stress on the liquid crystal panel can be reduced. There is also.

Further, if the light source is formed of a material that can transmit ultraviolet light and visible light, it is possible to reduce luminance unevenness generated in the liquid crystal panel. This makes it possible to set a high transmittance of, for example, a diffusion plate used for eliminating luminance unevenness of the liquid crystal panel, and as a result, it is possible to improve the luminance of an image displayed on the liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a perspective view of a direct type liquid crystal display according to an embodiment of the present invention.

FIG. 2 is a sectional view of a direct type liquid crystal display according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of attenuation of visible light in a direct type liquid crystal display according to the present embodiment.

FIG. 4 is an explanatory diagram of visible light attenuation when a reflection plate is provided in the direct type liquid crystal display according to the present embodiment.

FIG. 5 is an example of a characteristic diagram of a filter provided in a direct type liquid crystal display according to the present embodiment.

FIG. 6 is a perspective view of an edge-lit liquid crystal display according to a second embodiment of the present invention.

FIG. 7 is a sectional view of an edge-lit liquid crystal display according to a second embodiment.

FIG. 8 is a perspective view of a conventional direct type liquid crystal display.

9 is a cross-sectional view of the direct type liquid crystal display shown in FIG.

FIG. 10 is a diagram showing a structure of a hot cathode tube as an example of a fluorescent tube.

FIG. 11 is a perspective view of a conventional edge light type liquid crystal display.

FIG. 12 is a sectional view of a conventional edge light type liquid crystal display.

FIG. 13 is an explanatory diagram of visible light emitted from the backlight of the direct type liquid crystal display shown in FIG.

14 is an explanatory diagram of the amount of attenuation of visible light in the direct type liquid crystal display shown in FIG. 9;

FIG. 15 is an explanatory diagram of luminance unevenness occurring in the direct type liquid crystal display shown in FIG. 9;

[Explanation of symbols]

1 20 Liquid crystal display, 2 UV lamp, 3
22 light emitting plate, 4 filters, 5 diffusing plate, 6 liquid crystal panel, 7 21 reflecting plate, 8 protective film, 11 ultraviolet rays, 1
2 visible light, 23 protective film, 24 light guide

Claims (5)

[Claims] 1. A light source that emits light containing at least ultraviolet light, a light emitting unit that converts the ultraviolet light into visible light and emits light, and at least a filter that transmits the visible light and reflects the ultraviolet light. A lighting device, wherein the filter means and the light emitting means are arranged to face each other so as to contain the ultraviolet light emitted from the light source, and the filter means is arranged on the light emission side of the visible light. . 2. The lighting device according to claim 1, wherein a reflecting means for reflecting the ultraviolet light and the visible light is provided on a surface of the light emitting means opposite to the light source. 3. The lighting device according to claim 1, wherein the filter means reflects or absorbs infrared rays. 4. The lighting device according to claim 1, wherein the light source is formed of a material that transmits the ultraviolet light and the visible light. 5. The lighting device according to claim 1, wherein a transparent layer for protecting the light emitting means is provided on a surface of the light emitting means on the light source side.