JP2002258763A - Illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the electrification of a diffusion plate without using an antistatic agent. SOLUTION: The diffusion plate of the illuminator used as a direct backlight for a liquid crystal display device arranged with plural wire-shaped light sources on the back side of the diffusion plate is provided with light shielding patterns which constitute a lighting curtain for enhancing the uniformity of light by shielding the light of a range where the light from the wire-shaped light sources is strong. At least portions of the light shielding patterns consist of conductors and are connected to the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a so-called direct backlight in which a lamp is arranged below (at the back of) a diffusion plate, a resin plate such as an acrylic plate is used as the diffusion plate. Further, in the direct type backlight, a space is formed between the lamp and the diffusion plate, and the air space is occupied. As described above, since the diffusion plate is made of resin, the electric resistance value is generally as high as 10 ¹⁰ Ω or more. Therefore, the diffusion plate is very easily charged with static electricity. Typically electrical resistance value is not less than 10 ¹² Omega material has the property of charged electrostatically by friction with the air even when left in air, known to become easily charged even 10 ¹⁰ or more I have.

Resins such as acrylic and polycarbonate generally used as a material of a diffusion plate are 10 ¹⁰ Ω to ¹⁰ Ω.
^Since it has an electrical resistance value of ²⁰ Ω or more, it has the property of being very easily charged. In addition, in the direct backlight, an air layer is formed between the lamp and the diffusion plate, and the temperature of the lamp becomes 50 ° C. or more at the electrode portion or the like. Therefore, the direct-type backlight is in an environment where the diffusion plate is rubbed by convective air and is easily charged.

[0004] The diffusion plate charged as described above attracts minute foreign matters around it by static electricity. As a result, there is a problem that the light emission quality is deteriorated with the lapse of time.
Here, as the antistatic of the diffusion plate, a) application of an antistatic agent to the diffusion plate, b) kneading of the antistatic agent to the diffusion plate, and the like can be considered.

[0005]

However, in the application of the antistatic agent to the diffusion plate in a), there is a possibility that deterioration of light emission quality due to uneven application of the antistatic agent and deterioration of light emission quality due to bleeding may occur. In addition, even when the antistatic agent is mixed into the diffusion plate in b), deterioration in optical characteristics due to a decrease in transmittance of the diffusion plate due to the mixing, unevenness in quality due to uneven mixing during molding, deterioration over time, and the like. is there. Further, even when the treatments a) and b) are performed, the electric resistance value is often improved only to about 10 ⁸ Ω, and the treatment a) has a disadvantage that the effect cannot be obtained semipermanently.

In addition, the addition of an antistatic agent to the diffusion plate is expensive in terms of cost. The present invention has been made in view of such a problem, and an object of the present invention is to make it possible to effectively prevent charging without using an antistatic agent in a lighting device such as a direct type backlight. is there.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, a first technical means employed in the present invention comprises a light source and a non-conductive material, and light from the light source is directed to the outside. And a light-transmitting member that transmits light, wherein the light-transmitting member is formed with a conductor, and the conductor formed on the light-projecting member is grounded. According to such means, since the conductor formed on the light transmitting member is connected to the ground, even if the light transmitting member is charged, the static electricity escapes to the ground via the conductor, so that the charging can be effectively prevented. .

[0008] A second technical means employed in the present invention is a lighting device comprising: a light source; and a translucent member made of a non-conductive material and transmitting light from the light source to the outside. In the light-transmitting member, a light-shielding pattern serving as a lighting curtain for shielding a region where light is strong to increase the uniformity of light is formed, and at least a part of the light-shielding pattern is made of a conductor and grounded. It is characterized by being connected. According to the second means, since the lighting curtain also serves as a conductor for preventing electrification, it is possible to prevent the conductor from obstructing light unnecessarily.

A third technical means employed in the present invention is a lighting device used as a direct-type backlight for a liquid crystal display device in which a plurality of linear light sources are arranged on the back side of a diffusion plate. The diffusion plate is provided with a light-shielding pattern that serves as a lighting curtain for increasing the uniformity of light by shielding a strong range of light from the linear light source, and at least a part of the light-shielding pattern is made of a conductor. It is characterized by being grounded. According to the third means, since the lighting curtain also serves as a conductor for preventing electrification, it is possible to avoid obstruction of light by the conductor, and to maintain the quality as a backlight.

Preferably, the light-shielding pattern is formed continuously in the longitudinal direction of the linear light source in the vicinity immediately above the linear light source, or is formed linearly in the vicinity of a plurality of linear light sources. It is preferable that the plurality of light-shielding patterns formed continuously in the longitudinal direction of the light source are electrically connected to each other by a connection portion provided on a peripheral portion of the diffusion plate. Further, it is preferable that the connection portion is provided on the back surface of the diffusion plate, and the connection portion is provided in contact with a lighting device housing made of a conductor, so that the light-shielding pattern is grounded.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a direct-type backlight 1 which is a surface-emitting device as an example of a lighting device. This backlight 1 is for a liquid crystal display device. The direct-type backlight 1 includes a housing 2 which is a lighting device body.
A plurality of linear light sources 3 each composed of an elongated cathode discharge tube as a light source are arranged in a (chassis).

The housing 2 is formed of a conductive material such as a metal, and is formed in a box shape with an upper opening having side walls 2b erected from four sides of a rectangular bottom surface 2a. The interior of the housing 2 in which the linear light source 3 is housed is provided with a color having a good light reflectance such as white, and a light reflection layer (not shown) is formed. Therefore, the light emitted from the light source 3 is radiated from the upper opening of the housing 2 to the outside directly or after being reflected by the reflection layer. The plurality of linear light sources 3 are provided in the housing 3 in parallel at a predetermined interval from each other. Each light source 3 is connected to a power supply circuit 5 including an inverter and the like. The ground portion of the power supply circuit 5 is connected to the housing 3 made of a conductive material and is grounded.

On the upper part of the housing 2, there is provided a diffusion plate 6 made of a material in which light diffusing fine particles are blended with a transparent resin such as acrylic resin in a plate shape. An optical sheet such as a diffusion sheet is provided on the diffusion plate 6 as needed. The diffusing plate 6 has a light-transmitting property and a light diffusing action, and the surface of the diffusing plate 6 is a light emitting surface to which light from the light source 3 is irradiated. The diffusion plate 6 is also a light-transmitting member having a light-transmitting property and transmitting light to the outside of the device 1.
As shown in FIG. 2, an opaque light-shielding pattern 8 serving as a lighting curtain is formed on the back surface (light source side surface) 6 b of the diffusion plate 6. The lighting curtain is light source 3
The light is strong and bright immediately above, while the light between the light sources is relatively weak and dark to eliminate the darkness of light. At the position directly above the light source, the area of the light shielding pattern 8 is increased, and between the light sources, By reducing the area of the light shielding pattern 8, the uniformity of light is improved.

In FIG. 2, the light source 3 on the back side of the diffusion plate 6 is shown.
Are light-shielding patterns 8 serving as lighting curtains in parallel with the linear light sources 3 at positions just above the light sources 3 corresponding to the elongated linear light sources. In addition, a plurality of light-shielding patterns 8 are formed corresponding to a plurality of linear light sources 3. In addition, lighting curtain,
It is formed of a conductive material such as aluminum. FIG. 3 is an enlarged view of a portion A in FIG.
It is a pattern example of a lighting curtain. FIG. 3 (a)
Is a first example, in which a pattern 8a having a large area (hereinafter also referred to as a light blocking element) 8a is applied immediately above the light source 3, and a light shielding area having a smaller area becomes closer to the position between the light sources away from the vicinity immediately above the light source 3. Elements 8b, 8c, 8d are provided.

FIG. 3B shows a second example. In this second example as well, a light-shielding element 8e having a large area is provided immediately above the light source, and the light-emitting element 8e is separated from the area immediately above the light source 3 and located between the light sources. , Light-shielding elements 8f and 8g having small areas are provided. Note that the vertical direction in FIGS. 3A and 3B corresponds to the longitudinal direction of the linear light source 3. In the present invention, in order to prevent the diffusion plate 6 made of a non-conductive material from being charged easily, the diffusion plate 6 is charged by bringing a conductor into contact with the diffusion plate 6 and grounding the conductor. Allows electricity to escape to ground.

When charging is prevented by contacting a conductor, it is preferable to contact the conductor with the entire diffusion plate 6 in order to effectively prevent charging. If a conductor is inadvertently contacted, the light is blocked by the conductor, and the light transmittance of the diffusion plate 6 is reduced. In the present embodiment, the light shielding elements 8a, 8b, 8c, 8d, 8e, 8f,
Since 8 g is made of a conductive material, the lighting curtain also serves as a conductor for preventing static electricity, so that the conductor can be brought into contact with the diffusion plate 6 without causing a problem of a decrease in light transmittance. it can. In other words,
Since the conductor is placed just above the strong light source,
There is little problem that light is blocked by the conductor.

Here, all the light shielding elements provided on the diffusion plate 6 may be grounded, but in the example of FIGS. 3A and 3B, not all the light shielding elements are grounded. . In FIG. 3A, the light shielding element 8a at a position directly above the light source 3 is formed so as to extend continuously in parallel with the linear light source 3, and this light shielding element 8a is a ground light shielding element to be grounded. ing. Other light shielding elements 8b, 8c, 8
d is a non-earth light-shielding element that is present on the diffusion plate 6 in a scattered manner, is electrically separated from the ground light-shielding element, and is not connected to the ground.

In FIG. 3B, a plurality of scattered light shielding elements 8e located immediately above the light source 3 are electrically connected by a conductor wiring pattern 10 which is thinner than the light shielding elements 8e. , A light-shielding element for ground extending continuously in parallel with the linear light source 3. Other light shielding elements 8f,
8g is a non-earth light-shielding element which is present at a scattered point on the diffusion plate 6 and is electrically separated from the ground light-shielding element. In FIG. 3B, the side of the light shielding element 8e is 1.2 mm, and the width of the wiring pattern 10 is 0.2 mm.
It is.

Ground light-shielding elements 8a, 8e, 10 extending parallel to the linear light source 3 are provided at a plurality of locations corresponding to the plurality of linear light sources 3, and are provided as ground light-shielding elements. The longitudinal ends are electrically connected to each other by a connection portion 12 made of a conductor. The connection part 12 is formed by the diffusion plate 6.
Is provided on the periphery. Since the peripheral portion of the light emitting surface of the backlight 1 is a non-light emitting portion, even if the connecting portion 12 is provided on the peripheral portion of the diffusion plate 6 which is a non-light emitting portion, there is little problem of blocking light. In addition, the connection part 12 is a diffusion plate 6
However, the conductor 13 may be provided on two sides parallel to the linear light source 3. That is, the conductor 1 is formed on the entire periphery of the diffusion plate 6 which is a non-light emitting portion.
2 and 13 can be formed, and the light-shielding pattern 8 (including the wiring pattern 10), the connection portion 12, and the conductor 13 are all electrically connected (having the same potential).

The light-shielding pattern 8 (including the wiring pattern 10), the connection portion 12, and the conductor 13 can be formed on the diffusion plate 6 in a thin film shape by printing or vapor deposition of a conductive material.
In the case of printing, especially silk printing, since the minimum dot of the mass-producible light-shielding element is up to 0.2 mm in diameter, it is preferable to connect conductors like wiring just near the light source and on the non-light-emitting surface. In the case of vapor deposition, since the minimum vapor deposition diameter can be made sufficiently small, a small light shielding element distant from the vicinity immediately above the light source may be connected by a thin conductor wiring pattern.

The method of applying the light-shielding pattern 8, the connection portion 12, and the conductor 13 is not limited to printing and vapor deposition. As shown in FIG. 4, the diffusion plate 6 provided with the light-shielding pattern 8 and the like has the surface 6b on which the light-shielding pattern 8 has been applied as shown in FIG.
It is installed in the housing 2 such that This diffusion plate 6
Is installed such that its peripheral edge is in contact with and supported by a receiving portion 15 formed on the upper edge of the housing 2. Therefore, the light-shielding pattern 8 as a lighting curtain is electrically connected to the housing 2 made of a conductive material via the connection portion 12 or the conductor 13. That is, the earth light shielding elements 8a, 8e, 10 are grounded to the housing 2, which is the reference potential of the device 1. The connection portion 12 and the conductor 13 provided on the peripheral edge of the diffusion plate 3 are also connection terminals to the housing 2.

When the housing 2 is made of a non-conductive material such as a resin, it is preferable to electrically connect the connection ends 12 and 13 to the ground of the power supply circuit 5 by using a conductive wire or the like. In order to confirm the effect of the present invention, an experiment was conducted using two types of diffusion plates as shown in FIG. FIG.
(A) is a diffusion plate according to the present invention, on which a lighting curtain formed by evaporating aluminum is formed (hereinafter, referred to as sample A). FIG. 5B shows a diffusion plate according to a comparative example, which has no lighting curtain (hereinafter, referred to as a sample B).

The diffusion plates of Samples A and B are both made of acrylic material, have an outer dimension of 300 × 200 (mm), and have a thickness of 2.0 mm. In the experiment, static electricity was generated by rubbing each of the samples A and B a prescribed number of times, and then, the static electricity was set on the housing 2 of the backlight 1 as shown in FIG. . FMX-001 manufactured by Simco Japan Co., Ltd. was used as the static electricity measuring device. As shown in FIG. 7, as a result of the experiment, Sample A of the present invention was obtained.
According to the results, the amount of static electricity was -0.3 kV, and that of the sample B of the comparative example was +4.6 kV, and the effect of the present invention was confirmed.

The antistatic effect by grounding the conductor provided on the diffusion plate can be expected to last semipermanently, unlike the application or kneading of an antistatic material.
There is no influence by bleeding of the antistatic agent. In addition, the present invention is applicable not only to backlights but also to all lighting devices in which a translucent member serving as a light emitting surface of light from a light source is made of a non-conductive material. 8 to 11 are disclosures of other technologies related to a direct backlight. When a liquid crystal display device is used for a television or a super-large monitor, the backlight unit is required to have a wide viewing angle, high luminance, and light weight. In order to achieve these requirements, a direct-type backlight in which a light source is disposed immediately below a liquid crystal is used.

In the direct-type backlight, a plurality of light sources 3 are arranged, and light emitted from the light sources is a combined light of light reflected by a reflective layer formed of a layer having a high reflectance and direct light. Thus, the light is emitted from the illumination surface (light emission surface).
Since the combined light has a non-uniform luminance distribution, the distance between the diffuser plate, which is the illuminating surface, and the reflective layer is kept at a certain width or more for uniformity. For thin applications, the spacing becomes narrower, so a lighting curtain is attached to the diffusion plate, or white dot printing is applied to form a lighting curtain, and the uniformity of brightness is controlled. .

However, the processing of the lighting curtain requires high precision, and if the pasting or printing is shifted, an uneven luminance distribution is generated. Further, the luminance distribution is also deteriorated by the displacement of the diffuser after processing. The technology disclosed in FIGS. 8 to 11 relates to means for easily adjusting the uniformity of luminance without applying a lighting curtain. FIG.
Similarly, in the backlight 1 of FIG. 8, a plurality of light sources 3 are arranged in parallel in a housing 2 at predetermined intervals. The inner surface of the housing 2 is covered with a reflection layer (reflection plate) made of a resin layer or a metal layer having a high reflectance. A diffusion plate 6 is formed on the housing 2 by molding a material obtained by mixing light diffusing fine particles with a transparent resin such as acrylic resin in a plate shape. The diffusion plate 6 is supported by a support pin 25 erected from the bottom of the housing 2 so as not to bend. A lighting curtain 8 is provided just above the light source 3 on the back surface of the diffusion plate 6, and cuts off just above the light source to make the luminance distribution uniform.

However, in the countermeasures for making the luminance uniform by the lighting curtain 8, high precision is required for the alignment at the time of processing, and the deviation in position deteriorates the luminance distribution as shown in FIG. Further, the luminance distribution is also deteriorated by the displacement of the diffuser plate 6 after processing. In the backlight of FIG. 10, by arranging a plurality of diffusion plates 6 on which no lighting curtain is provided, an air layer 26 having a low refractive index is generated between the diffusion plates 6 and 6, and the luminance is obtained even without the lighting curtain. Spread uniformly (see FIG. 11B). In addition, the luminance distribution becomes uniform from any angle with respect to the light emitting surface, and there is a concern about displacement of the diffusion plate. When the thickness of one diffusion plate 6 is increased, the luminance distribution is similarly made uniform, but the luminance is reduced. When a plurality of diffusion plates 6 are stacked, even with the same thickness, the brightness distribution can be made uniform while suppressing a decrease in brightness by the air layer 26. The number of diffusion plates 6 is particularly preferably two.

FIGS. 12 to 14 show still another technique of a direct backlight. The housing (housing) 2 of the backlight is generally made of metal in consideration of strength, heat dissipation, light shielding properties, and the like. Leakage occurs, loss of electric energy occurs, and the influence of the leak increases the variation in the lighting state of the light source 3 (lamp), causing a difference in lamp life and causing uneven brightness due to aging. Become. For this reason,
The life of the lighting device and thus the display device is shortened.

To solve this problem, FIGS.
In the backlight shown in FIG. 4, the housing 2 is formed of a material having lower conductivity than metal such as plastic, carbon resin, urethane resin, etc., thereby achieving a reduction in leakage and reducing a variation in lamp lighting state. Life can be extended. Further, since the specific gravity of a material such as plastic is smaller than that of metal, weight reduction can be achieved. In addition, about the material,
Various choices are possible for design reasons such as strength.

Further, as shown in FIG.
Ribs 30 for ensuring strength may be formed on the back surface of the dies. Further, in order to secure the strength, a conductive material may be used in a range or a portion where the influence of the leak is small or an allowable range / portion. For example, a metal reinforcing member 32 as shown in FIG. 14A may be attached to a corner of the housing 2 so as to be wet as shown in FIG.

[0031]

According to the present invention, a light transmitting member such as a diffusion plate is hardly charged with static electricity, dust is reduced, and deterioration of light emitting quality due to aging is prevented. In the case where a conductor provided on a light-transmitting member such as a diffusion plate also serves as a lighting curtain, deterioration of light emission quality can be prevented by providing a conductor for preventing static electricity.

[Brief description of the drawings]

FIG. 1 is a perspective view of a backlight according to the present invention.

FIG. 2 is a perspective view of a light source side surface (back surface) of a diffusion plate (light transmitting member).

FIG. 3 is a light shielding pattern of a lighting curtain.

FIG. 4 is a side view of the backlight unit.

FIG. 5 is a plan view showing a diffusion plate as a sample used in an experiment for confirming the effect of the present invention, where (A) is a sample A of the present invention and (B) is a sample of a comparative example. B.

FIG. 6 is a side view of the backlight unit showing an experimental state.

FIG. 7 is a table showing experimental results.

8A and 8B illustrate a backlight unit according to another disclosed example, in which FIG. 8A is a perspective view of a housing and the like, and FIG. 8B is a rear view of a diffusion plate.

FIG. 9 is a cross-sectional view of the backlight unit of FIG.

FIG. 10 is a sectional view of a backlight unit according to another disclosure example.

11A is a luminance distribution diagram of the backlight unit of FIG. 9, and FIG. 11B is a luminance distribution diagram of the backlight unit of FIG.

FIG. 12 is a cross-sectional view of a backlight unit according to another disclosure example.

FIG. 13 is a bottom view of the backlight unit of FIG.

14 (a) shows a reinforcing member, and FIG. 14 (b) is a bottom view of a housing to which the reinforcing member has been attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Direct-type backlight unit 2 Housing 3 Linear light source 6 Diffusing plate 8 Light shielding pattern (lighting curtain) 12 Connection part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA31Z FA41Z FB08 FC02 LA07 LA16 LA18 LA19 LA30 5G435 AA16 BB12 BB15 EE26 FF06 GG24 GG26 GG34 KK07

Claims (6)

[Claims] An illumination device comprising: a light source (3); and a light transmitting member (6) made of a non-conductive material and transmitting light from the light source (3) to the outside. A lighting device, wherein a conductor (8) is formed on the light member (6), and the conductor (8) formed on the light transmitting member (6) is grounded. 2. A lighting device comprising: a light source (3); and a light transmitting member (6) made of a non-conductive material and transmitting light from the light source (3) to the outside. The light member (6) is formed with a light-shielding pattern (8) serving as a lighting curtain for shielding light intense areas to increase light uniformity, and at least a part of the light-shielding pattern is made of a conductor. A lighting device characterized by being grounded together. 3. A lighting device used as a direct-type backlight for a liquid crystal display device in which a plurality of linear light sources (3) are arranged on the back side of a diffusion plate (6). And a light-shielding pattern (8) serving as a lighting curtain for shielding a range in which light from the linear light source (3) is intense and improving light uniformity, and at least a part of the light-shielding pattern (8) is provided. A lighting device comprising a conductor and grounded. 4. The light-shielding pattern (8) is formed continuously in the longitudinal direction of the linear light source (3) immediately above the linear light source (3). Lighting equipment. 5. A plurality of light-shielding patterns (8) formed continuously in the longitudinal direction of the linear light source (3) in the vicinity immediately above the plurality of linear light sources (3), the periphery of the diffusion plate (6). 5. The lighting device according to claim 3, wherein the lighting device is electrically connected to each other by a connection portion provided in the portion. 6. The connection part (12) is provided on a back surface (6b) of the diffusion plate, and the connection part (12) is provided in contact with a lighting device housing (2) made of a conductor. The lighting device according to claim 5, wherein the light-shielding pattern is connected to ground.