KR20020046962A - Surface lighting device - Google Patents

Abstract

PURPOSE: A surface lighting apparatus is provided to improve the quality of image displayed on an LCD(Liquid Crystal Display) panel by illuminating the LCD panel with uniform brightness distribution. CONSTITUTION: A surface lighting device(10) has a light guiding plate(11) having a light incident surface formed at one end surface and a light exit surface formed on a front surface thereof; an elongated light source facing the light incident surface; a light source reflector reflecting light emitted from the elongated light source toward the light incident surface; a prism sheet(14) arranging minute parallel prism projections facing the light exit surface; a regular reflection type reflector facing the rear surface of the light guiding plate; a light guiding device guiding light emitted from the elongated light source to two portions of the light incident surface facing opposite ends of the elongated light source respectively; and a diffuser formed on the light incident surface to diffuse incident light.

Description

Surface lighting device

BACKGROUND OF THE INVENTION The present invention relates to an edge-light type surface lighting device (e.g., LCD panel lighting device) used in, for example, LCDs for notebook personal computers and LCD TV sets.

In recent years, color LCDs have been widely used in a variety of applications, including notebook personal computers, cellular phones and LCD TV sets. As information technology advances, LCDs have been required to have the capability to meet specific needs in response to the increasing amount of information to be managed, the variety of needs, and multimedia compatibility. A common need for manufacturers is to increase the brightness and resolution of LCDs to meet those requirements.

LCDs generally consist of two parts: an LCD panel and a backlight unit. The structure of the surface lighting device is roughly divided into two types: direct and edge light. In the direct type, a light source (eg CCFL tube) is located below the radiation plane. The edge light type surface lighting apparatus uses one straight lamp (CCFL lamp) along one end of the LCD, two lamps on opposite ends of the LCD, or an L-shaped lamp along opposite corners of the LCD. Edge light type is more popular than direct type because it has the advantage of reducing the size of LCD.

Mobile notebook personal computers and TV sets employing color LCDs generally use batteries (eg, rechargeable NiMH packs or lithium ion battery packs). Color LCDs, especially their surface lighting devices, consume most of the battery power. Therefore, reducing the power consumption of the surface lighting device as much as possible has become an important challenge for manufacturers who want to extend the battery life and improve the practical value of LCDs.

However, if reducing the power consumption of the surface lighting device should sacrifice the brightness of the surface lighting device, the contrast is low, which is undesirable. By improving the optical efficiency of the surface lighting device, it is desirable to reduce its power consumption while increasing the brightness of the surface lighting device.

In response to this desire, new types of surface lighting devices have been developed. In this new type of surface lighting device, a lens portion is formed directly on the light exit surface of a light guiding plate (used as an element of the surface lighting device), and an prism formed thereon is an array of prisms each having a triangular cross section. The sheet is positioned on the light guide plate such that the prism array faces the light guide plate. According to this structure, the light collected by the lens portion formed on the light guide plate is emitted obliquely from the light guide plate and then proceeds toward the front of the device to achieve high brightness.

Another type of surface lighting apparatus having a light guide plate formed such that the linear protrusions and the recesses extend in a direction substantially perpendicular to the light incidence plane of the light guide plate has been developed. According to this structure, the light spread in a direction parallel to the light incidence plane of the light guide plate is condensed by the lens effect generated by the linear protrusions and the concave portions to achieve high brightness.

If there is a defect on the screen of the LCD, this defect is unobtrusive and is perceived as a serious defect because the user always looks at the screen constantly. Such defects can occur in the form of bright and dark streaks, for example, near one end of the light guide plate. For example, the portion of the LCD screen facing the non-light emitting portion of the surface lighting apparatus near the end where the electrode portion of the linear lamp emerges may have a light incidence surface where the light guide plate has a length longer than the length of the light emitting portion of the linear lamp, rather than the rest of the screen. If it does, it looks a bit darker.

In order to solve this problem, it has been proposed that the light incident surface of the light guide plate is formed as a mat surface so that incident light is diffused to reduce the occurrence of light and dark stripes.

However, if the brightness of the surface lighting device is increased to meet the recent demand for further improvement of the brightness of LCDs, the above-mentioned deficiency becomes more apparent.

In a typical edge light type surface lighting device, a bundle of light emitted from a linear lamp is incident on one end surface of the light guide plate so as to come from a predetermined light exit surface on one side of the light guide plate. The LCD panel is positioned on a light exit surface with one or more diffuser sheets and / or prism sheets are positioned between the LCD panel and the light exit surface. Each prism sheet is a conventional optical element provided with an array of fine parallel prism protrusions having a refractive function and a reflective function thereon. The light bundles emitted from the light exit surface of the light guide plate proceed to the LCD panel through the prism sheet. Although prism sheets of one or two thicknesses are commonly used, there are limitations in collecting light diffused into the prism sheets.

It is an object of the present invention to provide a surface lighting apparatus for illuminating an LCD panel with a less uniform luminance distribution.

Another object of the present invention is to provide a surface lighting apparatus having a high brightness to improve the quality of the images displayed on the LCD panel.

1 is an exploded perspective view of a first embodiment of a surface lighting apparatus according to the present invention;

2 is a plan view of the light guide plate and the linear lamp shown in FIG.

3 is a graph showing an example of a printed pattern printed on the diffuse reflection surface of the reflector shown in FIG. 14A;

4 is an explanatory diagram of a printing pattern shown in FIG. 3;

FIG. 5 is a conceptual diagram illustrating ink particles used for printing a print pattern shown in FIG. 4, illustrating a particle size and a pitch of ink particles; FIG.

6 is a perspective view of a second embodiment of a surface lighting apparatus according to the present invention;

7 is a plan view of the light guide plate and the linear lamp shown in FIG.

8 is a fragmentary plan view of a basic part of a second embodiment of a surface lighting apparatus;

9 is a fragmentary perspective view of the basic part of the second embodiment of the surface lighting apparatus;

10A is a configuration diagram of basic optical elements of a comparative example of a surface lighting device having basic optical elements in a typical arrangement;

FIG. 10B is a view showing the configuration of the basic elements of the second embodiment of the surface lighting apparatus, similarly to the diagram of FIG. 10A;

11 is a plan view of a light guide plate and a linear lamp of a third embodiment of a surface lighting apparatus according to the present invention;

12A is a fragmentary plan view of a light guide plate and a linear lamp of a fourth embodiment of a surface lighting apparatus according to the present invention;

12B is a plan view of the light guide plate and the linear lamp of the surface lighting apparatus shown in FIG. 12A;

13 is a fragmentary perspective view of the basic elements of a fifth embodiment of a surface lighting apparatus according to the present invention;

14A is a plan view of a light guide plate and a linear lamp of a seventh embodiment of a surface lighting apparatus according to the present invention;

14B is a plan view of a light guide plate and a linear lamp of an eighth embodiment of a surface lighting apparatus according to the present invention;

FIG. 15 is a table of data of luminosity and half width distribution angles at the central portion of the light guide plates of Example 1 and Comparative Example 1; FIG.

16 is another embodiment of the light guide plate shown in FIG. 6;

17 is a fragmentary perspective view of the basic elements of a sixth embodiment of a surface lighting apparatus according to the present invention;

18 is a graph showing a change in the intensity of light emitted from the light guide plate of Comparative Example 2 due to a change in distance from the surface lighting apparatus;

FIG. 19 is a graph showing a change in luminance of light emitted from the light guide plate of Example 2 due to a change in distance from a light incidence plane, similar to that shown in FIG. 18;

* Explanation of symbols for main parts of the drawings

10 surface lighting device 11: light guide plate

11a and 11b prism protrusions 11c light incident surface

12: linear lamp 13: reflector

14: prism sheet 15: diffusion sheet

16 LCD panel 17 Reflector

According to an aspect of the present invention for achieving the above object, a light guide plate having a light incident surface formed on one end surface of the light guide plate and a light exit surface formed on the front surface of the light guide plate; An elongated light source facing the light incident surface; A light reflector reflecting light emitted from the elongated light source toward a light incident surface; An array of microparallel prism protrusions formed on one side of the prism sheet, and the prism sheet positioned such that the array of microparallel prism protrusions faces the light exit plane; A regular reflective reflector positioned to face the back of the light guide plate; A light guide guiding light emitted from the elongated light source to each of two portions of the light incidence surface that respectively face opposite ends of the elongated light source; And a diffuser formed on the light incident surface and including a diffuser for diffusing the incident light.

In an embodiment, a diffuse reflector is formed over the specular reflector to diffuse a portion of the light incident on the specular reflector.

In an embodiment, the light incident surface is inclined with respect to the plane perpendicular to the light exit surface.

Preferably, the light guide plate comprises: a first array of microparallel prism protrusions formed to extend in a first direction at one of a front surface and a rear surface of the light guide plate; And a second array of microparallel prism protrusions formed to extend in a second direction perpendicular to the first direction on the other of the front and rear surfaces of the light guide plate.

Preferably, the first direction described above is parallel to the axial direction of the elongated light source.

In an embodiment, the light guide plate has a substantially wedge-shaped cross-section, the thickness of the light guide plate gradually decreases in a direction away from the light incidence plane, the first angle between the light incidence plane and the light exit plane of the light guide plate, and the light incidence plane and the back side of the light guide plate The second angle of the liver is one of an acute angle, a right angle, and an obtuse angle, respectively.

Preferably, the light incidence surface formed on one end surface of the light guide plate and the other end surface of the light guide plate located on the opposite side of the light guide plate at the light incidence surface are parallel to each other.

In an embodiment, the light reflector comprises a second diffuser for diffusing light emitted from the elongated light source.

In an embodiment, the light reflector prevents light emitted from the elongated light source from entering the light exit surface from the front side thereof, and further prevents other light emitted from the long light source from entering the back side of the light guide plate from the rear side thereof. It includes an abnormal light shield.

In an embodiment, the abnormal light shield includes: front and rear tongue portions integrally formed with the light reflector so as to extend along the light exit surface and the back surface of the light guide plate in a direction away from the elongated light source; And front and rear low reflectivity regions positioned between the front portion and the light exit surface of the light guide plate and between the back tongue portion and the back portion of the light guide plate, respectively.

In an embodiment, the front and back bottom reflectance regions are formed on the front and back tongue portions, respectively.

In an embodiment, the light guide comprises two light guide members fixed to opposite ends of the elongated light source to respectively surround two electrode portions formed at opposite ends of the elongated light source.

In an embodiment, each of the two light guide members is formed as a cylindrical lid that fits into a corresponding one of the electrode portions.

In an embodiment, the light guide includes two inclined face portions formed at the light incident surface of its opposite ends near two electrode portions respectively formed at opposite ends of the elongated light source. Each of the two inclined surface portions is inclined with respect to the elongated light source so as to gradually approach a corresponding one of the electrode portions in a direction away from the central surface portion of the light incident surface.

In an embodiment, the light guide comprises two arcuate surface portions formed in the light incident surface at its opposite ends near the two electrode portions respectively formed at opposite ends of the elongated light source. Each of the two arc surface portions is bent to gradually approach a corresponding one of the electrode portions in a direction away from the center surface portion of the light incident surface.

In an embodiment, the light guide comprises: at least one first surface on which a portion of the light emitted from the elongated light source is incident; And at least one second surface for reflecting light incident on the at least one first surface to propagate inwardly of the light guide plate.

Preferably, the at least one first surface is angled by an angle of approximately 40 to 55 degrees with respect to the at least one second surface.

Preferably, at least one first surface and at least one second surface each comprise a plurality of first surfaces and a plurality of second surfaces that form two serrated portions at opposite ends of the light incident surface. Configure.

In an embodiment, each of the at least one first surface and the at least one second surface is formed as a mat surface.

In an embodiment, the light incident surface is formed as a mat surface.

In an embodiment, the median average surface height of the mat surface is in the range of 0.4 µm to 1.0 µm.

In an embodiment, the prism sheet includes an abnormal light shield that prevents light emitted from the elongated light source from entering the light incident surface from its front face.

In an embodiment, the prism sheet is slightly moved in a direction away from the light incidence surface with respect to the light guide plate so that a predetermined space is formed between the light shielding strip and the light exit surface, and the abnormal light shield is one of the prism sheets facing the long light source. It includes a light shielding strip located above a predetermined space so as to extend from the end.

Preferably, in the direction perpendicular to the longitudinal direction of the light incident surface and parallel to the light exit surface, the width of the space between the light incident surface and one end of the prism sheet is in the range of 0.5 mm to 10.0 mm.

In an embodiment, each of the light guide plate and the specular reflector is formed as a rectangular plate, and the diffuse reflector comprises two diffuse reflecting surfaces each formed at its two corners facing opposite ends of the elongated light source in front of the specular reflector do.

In an embodiment, each of the two diffuse reflecting surfaces comprises an ink print pattern printed on the front side of the specular reflector such that the degree of light diffusion of the diffuse reflecting surface decreases toward the center of the front side of the specular reflector, the high diffusion Ink having reflectivity is used to print an ink print pattern.

In an embodiment, the diffuse reflector comprises a diffuse reflecting surface formed in front of the specular reflector such that the elongated light source extends parallel to the elongated light source along one side of the adjacent specular reflector.

In an embodiment, the diffuse reflecting surface comprises an ink print pattern printed on the front side of the specular reflector such that the degree of light diffusion of the diffuse reflecting surface increases toward the specular reflector adjacent to the elongated light source, the ink having a high reflectivity of reflectance Is used to print the ink print pattern.

According to another aspect of the invention, a light guide plate having a light incident surface formed on one end surface of the light guide plate and a light exit surface formed on the front surface of the light guide plate; And an elongated light source facing the light incident surface. The light incident plane is inclined with respect to the plane perpendicular to the light exit plane.

Preferably, the light guide plate comprises: a first array of microparallel prism protrusions formed to extend in a first direction at one of a front surface and a rear surface of the light guide plate; And a second array of microparallel prism protrusions formed to extend in a second direction perpendicular to the first direction on the other of the front and rear surfaces of the light guide plate.

In an embodiment, the light guide plate has a substantially wedge-shaped cross section, and the thickness of the light guide plate is gradually decreased in a direction away from the light incidence plane, the first angle between the light incidence plane and the light exit plane of the light guide plate, and the light incidence plane of the light guide plate. And the second angle between the back surface is one of an acute angle, a right angle and an obtuse angle, respectively.

Preferably, the light incidence surface formed on one end surface of the light guide plate and the other end surface of the light guide plate located on the opposite side of the light guide plate from its light incidence surface are parallel to each other.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The surface lighting apparatus 10 of the first embodiment shown in FIG. 1 is used as an LCD panel lighting apparatus, and includes a light guide plate 11 and a linear lamp (fluorescent lamp) 12. The surface lighting apparatus 10 further includes a reflecting plate 13, a prism sheet 14, a diffusion sheet 15, an LCD panel 16, and a reflector 17. The reflecting plate 13 is a regular reflection type in which the reflection angle of the incident light is the same as the incident angle and opposite to the normal at the point of incidence. The light guide plate 11 is formed to have a rectangular shape in plan view, and is made of a resin material through which light can pass. The light guide plate 11 is provided with a light incidence surface 11c at one end surface thereof. The linear lamp 12 is located adjacent to the light incident surface 11c and extends along the light incident surface 11c. On the front surface of the light guide plate 11 (upper surface shown in FIG. 1), a first array 11a of fine and parallel prism protrusions extending in parallel to the linear lamp 12 is provided. The rear surface of the light guide plate 11 (lower surface shown in FIG. 1) is provided with a second array 11b of fine and parallel prism protrusions extending in a direction perpendicular to the linear lamp 12. Thus, the first and second arrays 11a and 11b of the microparallel prism protrusions extend in directions perpendicular to each other. FIG. 2 schematically shows an orthogonal relationship between the first and second arrays 11a and 11b of these microparallel prism protrusions. The inner angle α (see FIG. 1) at the apex of each prism protrusion of the first arrangement 11a of the microparallel prism protrusions is preferably in the range of approximately 165 to 177 degrees, and the second arrangement of the microparallel prism protrusions ( The internal angle (β; see Fig. 1) at the apex of each prism protrusion of 11b) is preferably in the range of approximately 120 to 150 degrees. The pitch S of the prism protrusions of each array of the first and second arrays 11a and 11b (see Fig. 1) is preferably in the range of approximately 20 to 90 mu m. The first array 11a of the prism protrusions and the first array 11b of the prism protrusions are formed on the rear surface and the front surface (light emitting surface) of the light guide plate 11, respectively. In this case, the angle α at the apex of each prism protrusion of the first array of prisms 11a is preferably in the range of approximately 165 to 177 degrees, while the prism of each prism of the second array of prisms 11b is in the range of approximately 165 to 177 degrees. The internal angle β at the apex of the projection is in the range of approximately 85 to 95 degrees. The first and second arrays 11a and 11b of the prism protrusions are integrated with the light guide plate 11 when the light guide plate 11 is molded. That is, the ultra-precision molding die (not shown) for molding the light guide plate 11a includes fine protrusions and recesses that individually correspond to the fine protrusions and recesses that form respective arrays of the prism protrusions 11a and 11b. To be prepared. The light guide plate 11 may be made of, for example, acrylic resin as a whole.

The light guide plate 11 is positioned on the reflecting plate 13. The prism sheet 14, the diffusion sheet 15, and the liquid crystal cell (LCC) 16 are positioned in order from the rear side to the front side of the surface lighting apparatus 10 on the light guide plate 11. Each of the reflecting plate 13, the prism sheet 14, the diffusion sheet 15, and the LCD panel 16 is formed to have a rectangular shape in plan view so as to correspond to the planar shape of the light guide plate 11.

As shown in FIG. 1, the linear lamp 12 is surrounded by a reflector 17 having a substantially U-shaped cross section at a plane perpendicular to the axis of the linear lamp 12. Light emitted from the linear lamp 12 toward the light incident surface 11c (i.e., the right side shown in FIG. 1) is incident directly on the light incident surface 11c, but is incident from the linear lamp 12 to the light incident surface 11c. The light emitted in the direction away from) is reflected at the inner surface of the reflector 17 so as to be incident on the light incident surface 11c.

Therefore, the light bundle emitted by the linear lamp 12 enters the light guide plate 11 through the light incident surface 11c. Subsequently, the light bundle is reflected by the inner surfaces of the light guide plate 11 more than once, and a portion of the light bundle is incident on the prism sheet 14 and the diffusion sheet 15 so as to enter the first array of prism protrusions from the light guide plate 11. Come out through 11a to illuminate the LCD panel 16 from behind. The other portion of the light bundle exits from the light guide plate 11 through the second array 11 of prism protrusions 11b and then reflects through the second array 11 of prism protrusions 11b to enter the reflecting plate 13. The LED panel 16 is illuminated from the back through the first array 11a of prism protrusions from the light guide plate 11 so as to reenter the light and eventually enter the prism sheet 14 and the diffusion sheet 15. The first array 11a of the prism protrusions has a function of causing the light moving in the light guide plate 11 to come out from the front thereof. The inner angle α (see FIG. 1) of each of the prism protrusions of the first array of prism protrusions 11a is determined so that light traveling in the light guide plate 11 can come out from the front as uniformly as possible. On the other hand, the second array 11b of prism protrusions serves as a condensing lens for concentrating the light reflected by the rear surface of the light guide plate 11 toward its front side. This also increases the brightness of the surface lighting device.

Therefore, it is possible to reduce the number of expensive prism sheets by adopting the light guide plate 11 in which the arrays 11a or 11b of the prism protrusions are integrally formed on each side. This is advantageous in reducing the number of components of the surface lighting apparatus 10 and its manufacturing cost.

6 and 7 show a second embodiment of the surface lighting apparatus. The surface lighting apparatus 30 of the second embodiment is used as an LCD panel lighting apparatus, and includes a light guide plate 31 and a linear lamp (fluorescent tube / long light source; 32). The surface lighting device 30 further includes a prism sheet 33, a reflector (reflective reflector) 34, and a tube reflector (light reflector) 35. The reflector plate 34 is a regular reflective type. The light guide plate 31 is formed such that its planar shape has a rectangular shape, and is made of a resin material through which light passes. The linear lamp 32 is located along one end surface of the light guide plate 31. One end surface of the light guide plate 31 is provided with a light incident surface 31a facing the straight lamp 32. The front surface (upper surface shown in Fig. 6) of the light guide plate 31 is formed as the light exit surface 31b. The reflector plate 34 is located behind the light guide plate 31. The reflecting plate 34 reflects the light coming from the back surface of the light guide plate 31 back toward the light exit surface 31b, so that the reflecting plate 34 is not affected by diffusion, thereby achieving high brightness. The light incidence surface 31a of the light guide plate 31 is formed as a mat surface so that the light incidence surface 31a serves as a diffusion surface (diffuser) 36 for diffusing light incident on the light incidence surface 31a. The median average surface height Ra of the light incident mat surface 31a is in the range of 0.4 to 1.0 mu m. Although the diffusion surface 36 shown in FIG. 4 is formed as a mat surface, the diffusion surface may be formed in any other way as long as light incident on the incident surface 31a is diffused thereby.

On the back side (lower side shown in FIG. 6) of the prism sheet 33, an array 33a of fine parallel prism protrusions each having a triangular cross section is provided. The prism sheet 33 is positioned on the light guide plate 31 such that the array of prism protrusions 33a faces the light guide plate 31.

10A is a schematic diagram of basic optical elements of a comparative example of a surface lighting device having a typical arrangement of basic optical elements. In the surface illuminating device of this comparative example, the prism sheet 33 is positioned on the light guide plate 31 such that the vertices of the prism protrusions 33a face away from the light exit surface 31b of the light guide plate 31. In this case, it is preferable that the cabinet angle α shown in Fig. 10A is approximately 90 degrees. Since the vertices of the prism protrusions 33a are facing away from the light exit surface 31b, the diffusion sheet 50 is positioned between the prism sheet 33 and the light guide plate 31, as shown in FIG. 10A. Then, the light from the light exit surface 31b of the light guide plate 31 is refracted by the prism protrusions 33a to go out to the front side (upper side shown in Fig. 10A) of the surface lighting apparatus.

FIG. 10B is a view similar to that of FIG. 10A, showing a schematic view of the basic elements of the surface illumination device 30 of the second embodiment. As shown in FIG. 10B, in the surface lighting apparatus 30 of the second embodiment, the prism sheet 33 is arranged so that the peaks of the prism protrusions 33a face the light exit surface 31b of the light guide plate 31. Is located above. In this case, it is preferable that the cabinet α shown in Fig. 10B is approximately 60 to 70 degrees.

In the surface illuminating device 30 of the second embodiment shown in FIG. 6, the light exiting from the light exit surface 31b of the light guide plate 31 is directly incident on the prism sheet 33 and is caused by the refractive index of the prism protrusions 33a. Go to the front of the surface lighting device (30).

Therefore, in the surface lighting apparatus 30 of the second embodiment, the light collected through the light guide plate 31 comes from the light guide plate as shown in FIG. 10B. This causes the brightness at the light exit surface 31b of the light guide plate 31 to be significantly increased compared to the structure shown in FIG. 10A.

When a movable power source (e.g., a battery pack) is used as the power source for the surface lighting device, the power supplied from the movable power source to the surface lighting device switches the brightness of the surface lighting device to the minimum brightness that substantially extends the battery life. By doing so, it can be reduced to a minimum.

As shown in FIG. 6, the linear lamp 32 is surrounded by a tubular reflector 35. The tubular reflector 35 has a C-shaped cross section at a surface perpendicular to the linear lamp 32, so that the portion of the tubular reflector 35 facing the light incident surface 31a is opened. Therefore, the light emitted from the linear lamp 32 toward the light incident surface 31a (i.e., the right side shown in FIG. 6) directly enters the light incident surface 31a through the open portion of the tubular reflector 35. The light emitted from the linear lamp 32 in the direction away from the light incident surface 31a is reflected by the tubular reflector 35 and then enters the light incident surface 31a through the open portion of the tubular reflector 35. .

The tubular reflector 35 has a diffuse reflection surface 35a such as a diffusion sheet attached to the inner surface of the tubular reflector 35 on an inner surface facing the straight lamp 32.

In the above-described arrangement in which the diffuse reflection surface 35a and the diffused surface 36 are respectively provided on the light incident surface 31a of the tubular reflector 35 and the light guide plate 31, the light emitted by the linear lamp 32 is The light is diffused by the diffuse reflection surface 35a and the diffuser surface 36 to uniformly enter the light guide plate 31. This prevents light and shade stripes A (see FIG. 7) from occurring near the end of the light exit surface 31b of the light guide plate 31 adjacent to the linear lamp 32, so that the part of the light guide plate 31 near the light exit surface 31b. And a difference in brightness does not occur between the center portion of the light guide plate 31. As a result, the brightness of the light exit surface 31b becomes uniform.

As shown in FIG. 7, electrode portions 32a (non-light emitting portions) are provided at opposite ends of the linear lamp 32. As the screen size of the notebook personal computer increases, the length of the linear lamp 32 (except the length of each electrode portion 32a) becomes shorter with respect to the length of the light incident surface 31a. If the length of the linear lamp 32 excluding the length of each electrode portion 32a is shorter than the length of the light incident surface 31a, that is, the length of the light emitting portion of the linear lamp 32 is the length of the light incident surface 31a. If shorter than the length, a dark portion B (see FIG. 7) occurs at two corners of the light guide plate 31 (each facing opposite ends of the linear lamp 32) due to the lack of light quantity.

In order to prevent this problem from occurring, in the surface lighting apparatus 30 of the second embodiment, the light guiding member (light guide) 37 is provided at each of the opposing ends of the linear lamp 32, that is, each electrode portion 32a. , See FIG. 8). Each light guide member 37 guides the light emitted from the linear lamp 32 toward the portion of the light incident surface 31a facing the corresponding end of the linear lamp 32. Each light guide member 37 has a cylindrical lid shape whose outer end (left end shown in Fig. 8) is closed and is made of a transparent or translucent material (for example, glass or transparent acrylic resin). Each cylindrical light guide member 37 is fitted to the corresponding electrode portion so as to surround the corresponding electrode portion 32a.

Each cylindrical light guide member 37 receives the first light beam Y1 (shown by an arrow in FIG. 8) obliquely emitted from the linear lamp 32, and receives the received light beam Y1 as a second light beam Y2, in FIG. 8. Projected toward the portion of the light incident surface 31a facing the corresponding end of the linear lamp 32 in the range L shown in FIG. This increases the brightness at each of the two corners of the light guide plate 31 facing the opposite ends of the straight lamp 32, thereby preventing the dark portion B from occurring at each of the two corners of the light guide plate 31. do.

Notebook personal computers are generally small in size and are often carried from one place to another, so the straight lamp 32 must be resistant to vibrations. The cylindrical light guide members 37 house and hold the electrode portions 32a of the linear lamp, respectively. Thus, the cylindrical light guide members 37 reinforce the fixing portions of the electrode portions 32a of the linear lamp 32 and increase the resistance to the vibrations of the electrode portions 32a.

The effect of preventing the dark portion B from occurring at each of the two corners of the light guide plate 31 may be achieved not only by the above-described structure shown in FIG. 8 but also by the structure shown in FIG. 11 shows the light guide plate 31 and the linear lamp 32 of the surface lighting apparatus of the third embodiment. In the surface illuminating device of the third embodiment, the light guiding members 37 shown in Fig. 8 are not used, and instead of the flat light incident surface 31a of the surface illuminating device of the second embodiment, It is substantially the same as the surface illumination device 30 shown in FIGS. 6 and 7 except that a light incidence surface 131a having a specific shape unique to the surface illumination device is provided. The light incident surface 131a of the light guide plate 31 faces two straight lamps 32 and has two inclined surface portions positioned at opposite ends of the central surface portion 131a1 and the central surface portion 131a1, respectively. (Light guide device) 131a2 is provided. The central surface portion 131a1 extends substantially parallel to the linear lamp 32 and has a predetermined space between the central surface portion 131a1 and the linear lamp 32. Two inclined surface portions 131a2 are respectively formed near the two electrode portions 32a of the linear lamp 32, and each of the inclined surface portions 131a2 is inclined with respect to the linear lamp 32 and is centered. It gradually approaches the corresponding electrode portion 32a in a direction away from the surface portion 131a1.

Therefore, the light emitted from the linear lamp 32 in the direction perpendicular to the axial direction of the linear lamp 32 is incident on the central surface portion 131a1. Furthermore, light emitted in an oblique direction outward from each of the opposing ends of the light emitting portions of the linear lamps 32 adjacent to the two electrode portions 32a is incident on the corresponding inclined surface portion 131a2, 2 Light emitted from each of the opposite ends of the light emitting portion of the linear lamp 32 adjacent to the two electrode portions 32a also enters the corresponding inclined surface portion 131a2. According to the light guide plate 31 of this structure, the light incidence surface 131a of the light guide plate 31 is not only from the linear lamp 32, that is, from the large portions of the center of the linear lamp 32, but also to the electrode portions 32a, respectively. The light emitted from the opposite ends of the light emitting portions of the adjacent linear lamps 32 is uniformly received. Thus, the brightness at each of the two corners of the light guide plate 31 facing the opposite ends of the linear lamp 32 is improved. This prevents the dark portions B shown in FIG. 7 from occurring.

The light incident surface 131a shown in FIG. 11 may be replaced by the light incident surface 231a shown by the dashed line in FIG. 11 which achieves a similar effect. The light incident surface 231a faces the straight lamp 32 and includes two arc surface portions (light guide devices) positioned at opposite ends of the central surface portion 231a1 and the central surface portion 231a1, respectively; 231a2). The central surface portion 231a1 extends substantially parallel to the linear lamp 32 to have a predetermined space between the central surface portion 231a1 and the linear lamp 32. Two arc surface portions 231a2 are respectively formed near the two electrode portions 32a of the linear lamp 32, and each arc surface portion 231a2 is a linear lamp in a direction away from the center surface portion 231a1. It is curved so as to get closer to 32.

Therefore, the light emitted from the linear lamp 32 in the direction perpendicular to the axial direction of the linear lamp 32 is incident on the central surface portion 231a1. Furthermore, light emitted in an inclined direction outward from each of opposing end portions of the light emitting portions of the linear lamps 32 adjacent to the two electrode portions 32a respectively, enters the corresponding arc surface portion 231a2, Light emitted in a direction perpendicular to the linear lamp 32 from each of the opposite ends of the light emitting portion of the linear lamp 32 adjacent to the two electrode portions 32a is incident on the corresponding arc surface portion 231a2. do. According to the light guide plate 31 of this structure, the light incidence surface 231a is not only from the linear lamp 32, i.e., from the large part of the center of the linear lamp 32, but also from the linear lamp 32 adjacent to the electrode portions 32a. The light emitted from the opposite ends of the light emitting portion 32 is uniformly received. Thus, the brightness at each of the two corners of the light guide plate 31 facing the opposite ends of the linear lamp 32 is improved. This prevents the dark portion B shown in FIG. 7 from occurring.

12A and 12B show the basic parts of the fourth embodiment of the surface lighting apparatus according to the present invention. In the surface illumination apparatus of the fourth embodiment, the light guide plate 31 has a light incidence surface 331a having a specific structure unique to the surface illumination apparatus of the fourth embodiment instead of the flat light incidence surface 31a of the surface illumination apparatus of the second embodiment. Except that it is provided, it is substantially the same as the surface lighting apparatus 30 of the second embodiment shown in Figs. The light guide plate 31 has two serrated portions positioned at opposite ends of the light incidence surface 331a near the electrode portions 32a on its light incidence surface 331a facing the straight lamp 32. (Light guide device) 337 is provided. Each serrated portion 337 is made of an array of prism portions, with each prism portion having a first surface 337a and a second surface 337b. A portion of the light emitted from the linear lamp 32 is incident on the first surface 337a. Light passing through the first surface 337a is reflected from the inner surface of the second surface 337b and travels toward the portion of the light guide plate 31 facing the corresponding end of the linear lamp 32. The first surface 337a extends perpendicular to both the light incident surface 331a and the light exit surface 331b of the light guide plate 31, and the second surface 337b is the light incident surface 331a and the first surface. 337a is inclined to both and extends perpendicular to the light exit surface 331b. The internal angle formed between the first and second surfaces 337a and 337b of each prism portion is set in the range of approximately 40 to 55 degrees. Each serrated portion 337 (ie, the first surfaces 337a) extends in a direction parallel to the axial direction of the straight lamp 32. Each of the first and second surfaces 337a and 337b may be formed as a mat surface such that the first and second surfaces serve as a diffusion surface for diffusing incident light. In this case, the median average surface height of the mat surface is in the range of 0.4 to 1.0 mu m.

As shown in FIG. 12A, the light rays shown as dotted lines emitted obliquely from the linear lamp 32 and incident on one first surface 337a are totally reflected by the inner surface of the corresponding second surface 337b so that Proceed inward. Similarly, the other light rays emitted from the linear lamp 32 in a direction parallel to the axial direction and viewed as solid lines incident on the first surface 337a are totally reflected by the inner surface of the corresponding second surface 337b to guide the light guide plate 31. Proceed inside). Thus, each of the first surface 337a and the corresponding second surface 337b form an array of prism portions, so that light incident on each first surface 337a is due to the internal total reflection characteristics of the prism, and thus the corresponding surface. It totally reflects by the 2nd surface 337b, and it advances inwardly of the light guide plate 31. As shown in FIG. Thus, the brightness is improved at each of the two corners of the light guide plate 31 facing opposite ends of the linear lamp 32, respectively. This prevents the dark portions B shown in FIG. 7 from occurring. If the interior angle formed between each of the first surface 337a and the corresponding second surface 337b is set within the range of approximately 40 to 55 degrees as described above, the light incident on the first surface 337a is corresponding to the corresponding second surface 337a. It may be totally reflected by the surface 337b. This allows the light incident on the first surfaces 337a to propagate inwardly of the light guide plate 31 as much as possible. Therefore, the light incident on the first surfaces 337a may travel inside the light guide plate 31 to sufficiently prevent the dark portions B shown in FIG. 7 from occurring. Furthermore, by providing a light guide plate 31 having two or more prism portions each formed to be serrated by one first surface 337a and one second surface 337b, thereby opposing the straight lamps 32. It is possible to extend the light incidence area on the light incidence surface 331a in the vicinity of each of the two corners of the light guide plate 31 respectively facing the ends. This also helps to prevent the dark portions B shown in FIG. 7 from occurring.

Fig. 13 shows the basic parts of the fifth embodiment of the surface lighting apparatus. In the surface lighting apparatus of the fifth embodiment, the prism sheet 31 is slightly moved in a direction away from the light incident surface 31a with respect to the light guide plate 31, and the surface lighting apparatus is adjacent to the linear lamp 32. 6 and 7 except that an abnormal light shield 39 is further provided to prevent the light and dark stripes (A, see FIG. 7) from occurring near the end of the light exit surface 31b of (31). It is substantially the same as the surface lighting apparatus 30 of the second embodiment shown in FIG.

A light shielding strip (e.g., a light shielding film, 40) extending in parallel to both the linear lamp 32 and the light exit surface 31b is fixed to one end 33b of the prism sheet 33 facing the linear lamp 32. Thus, a predetermined space W is formed between the light shielding strip 40 and the light exit surface 31b. The abnormal light shield 39 is composed of a light shielding strip 40 and a space (W). The width of the space W from the light incident surface 31a to the end of the prism sheet 33 in a direction perpendicular to the longitudinal direction of the light incident surface 31a and parallel to the light exit surface 31b is preferably 0.5. To 10.0 mm.

In the surface lighting apparatus of the fifth embodiment shown in FIG. 13, the abnormal rays emitted from the linear lamp 32 and traveling from the front toward the light incident surface 31a do not enter the light exit surface 31b from the front surface. To be absorbed by the light shielding film 40. This prevents the light and dark stripes A (see FIG. 7), which may be generated due to such abnormal rays, from occurring near the end of the light exit surface 31b of the light guide plate 31 adjacent to the linear lamp 32.

17 shows the basic parts of the surface lighting apparatus of the sixth embodiment. In the surface lighting apparatus of the sixth embodiment, the dark and light streaks A (see FIG. 7) are provided near the end of the light exit surface 31b of the light guide plate 31 adjacent to the linear lamp 32 in the surface lighting apparatus of the sixth embodiment. It is substantially the same as the surface lighting apparatus 30 of the second embodiment shown in Figs. 6 and 7, except that an abnormal light shield 139 is further provided to prevent the light from being generated. The abnormal light shield 139 includes front and rear tongue portions 35b and front and rear bottom reflectance regions 120. The front and back tongues 35b are integrally formed with the tubular reflector 35 so as to be substantially mutually separated from the linear lamp 32 in a direction away from the front face (ie, the light exit surface 31b) and the light guide plate 31, respectively. Extend in parallel. The front and back low reflectivity regions 120 are formed on opposite inner surfaces of the front and back tongue portions 35b, respectively, so that the front low reflectance region 120 is the front tongue portion 35b and the light guide plate 31. The bottom reflectance region 120 is positioned between the front surface of the back tongue portion 35b and the back surface of the light guide plate 31. A thin gap is formed between the front low reflectance region 120 and the light exit surface 31b of the light guide plate 31, and a similar narrow gap is formed between the rear low reflectance region 120 and the surface of the light guide plate 31. do. The front and back bottom reflectance regions 120 form an ink print area on each of the opposing inner surfaces of the front and back tongue portions 35b, or the opposing inner surfaces of the front and back tongue portions 35b. Each of these can be formed by applying a coating of fine particles, such as fine beads.

In the tubular reflector 35 shown in FIG. 17, abnormal rays emitted from the linear lamp 32 and traveling from the front side toward the light incident surface 31a of the light guide plate 31 are incident on the light exit surface 31b from the front side. The other abnormal rays which are absorbed by the front low reflectance region 120 and emitted from the linear lamp 32 and proceed from the front side toward the rear surface of the light guide plate 31 are not emitted from the rear surface of the light guide plate. Absorbed by the back low reflectance region 120 to prevent the incident. This prevents light and dark stripes (A, FIG. 7), which may be generated due to such abnormal rays, from occurring near the end of the light exit surface 31b of the light guide plate 31 adjacent to the linear lamp 32.

Fig. 14A shows the basic parts of the seventh embodiment of the surface lighting apparatus according to the present invention, and Fig. 14B shows the basic parts of the eighth embodiment of the surface lighting apparatuses according to the present invention. Each of the surface illuminating devices of the seventh and eighth embodiments has a partial diffuse reflector which diffuses a portion of the light incident on the reflecting plate 34 onto the light exiting surface 31b of the light guide plate 31. It is substantially the same as the surface lighting apparatus of the second embodiment shown in Figs. In each of Figs. 14A and 14B, only the linear lamp 32 and the reflecting plate 34 are shown. In the surface lighting apparatus of the seventh embodiment shown in FIG. 14A, the reflecting plate 34 is formed in front of the reflecting plate 34 and parallel to the linear lamp 32 along the side of the reflecting plate 34 adjacent to the linear lamp 32. And a diffuse reflecting surface (partially diffuse reflector 41). Light incident on the diffuse reflection surface 41 diffuses and travels toward the light exit surface 31b. The diffuse reflection surface 41 increases its light diffusion degree toward the end of the reflecting plate 34 adjacent to the linear lamp 32 (upper end shown in Fig. 14A). The diffuse reflection surface 41 having such a light diffusing ability is formed by forming a dot pattern (print pattern) on a corresponding portion of the front surface of the reflecting plate 34, for example, with ink having a high diffuse reflection degree.

In the surface lighting apparatus of the eighth embodiment shown in FIG. 14B, the reflecting plate 34 has two diffuse reflecting surfaces 141 formed at two corners of the front side of the reflecting plate 34 facing opposite ends of the linear lamp 32. And a partial diffuse reflector). Each of the two diffuse reflection surfaces 141 is formed such that its degree of light diffusion decreases in the direction toward the front center of the reflecting plate 34. Similar to the diffuse reflection surface 41 shown in FIG. 14A, each diffuse reflection surface 141 having such a light diffusing ability has a high dot pattern (print pattern) on, for example, a corresponding portion of the front surface of the reflector plate 34. As shown in FIG. Diffuse reflectance is also formed by forming an ink having a diffuse reflectivity higher than the diffuse reflectivity of the ink used for the diffuse reflecting surface 41 shown in Fig. 14A.

According to the partial diffuse reflector 41 shown in FIG. 14A, dark and light streaks A (see FIG. 7) may occur near the end of the light exit surface 31b of the light guide plate 31 adjacent to the linear lamp 32. Can be prevented.

According to the partially diffused reflector 141 shown in FIG. 14B, each dark portion B (see FIG. 7) that may occur at each of the two corners of the light guide plate 31 facing the opposite ends of the linear lamp 32, respectively. Occurrence can be prevented.

3 is a graph showing an example of an ink print pattern printed on the diffuse reflection surface 41. 4 is an exemplary view of the ink print pattern shown in FIG. 5 is a conceptual diagram of the particles of the ink used to print the ink print pattern, showing the particle size d (particle diameter) and the pitch P of the ink particles (G). The degree of light diffusion of the diffuse reflection surface 41 (ie, the reflectance of the diffuse reflection surface 41) is a combination of the particle size d and the pitch P of the ink (color or transparent ink) conceptually shown in FIG. 5. Determined by In the example shown in Figs. 3 and 4, the diffuse reflection surface 41 is divided into six regions A, B, C, D, E and F, and the pitch P is fixed at 125 mu m (Fig. 5). The particle size d increases stepwise toward the end (upper end shown in FIG. 14A) of the reflecting plate 34 adjacent to the linear lamp 32, i.e., in the upward direction shown in FIG. Ink used to print an ink print pattern on the diffuse reflection surface 41 is a kind having a high diffuse reflectivity. Specifically, area A is a fill-in area (or a heavily shaded area), but particle sizes d of other areas B, C, D, E and F are 120 μm, 90 μm, It is set to 60 micrometers, 40 micrometers, and 20 micrometers, and changes a light-diffusion degree in steps. Zone A (filled zone) has a very high diffuse reflectivity and extends to overlap the area on the reflecting plate 34 corresponding to the display display area.

Each of the two diffuse reflecting surfaces 141 shown in FIG. 14B may be formed with an ink having a high diffuse reflectivity in a manner similar to that shown in FIGS. 3, 4 and 5.

Each diffuse reflection surface 41 or 141 is a coating of fine particles, such as microbeads, on the corresponding portion of the front side of the reflecting plate 34 as well as forming a printing pattern with ink on the corresponding portion of the front side of the reflecting plate 34. It can also be formed by applying. Although the work-surface pattern on the reflector plate 34 becomes larger than that upon ink application during microbead application, a similar effect can be expected upon application of microbeads. The characteristics of each of the surface lighting devices 10 of the seventh and eighth embodiments can be sufficiently utilized especially when the LCD panel is required to generate images of high brightness.

FIG. 16 shows another embodiment of the light guide plate 31 shown in FIG. 6. As shown in FIG. 16, the light guide plate 31 has a substantially wedge shape in which the thickness of the light guide plate 31 gradually decreases in a direction away from the light incident surface 31 a of the light guide plate 31, that is, in the right direction shown in FIG. 16. It has a cross section. Similar to the light guide plate 11 shown in FIG. 1, the light guide plate 31 has a first array of microparallel prism protrusions (not shown) extending in parallel to the linear lamp 32 (upper part shown in FIG. 16). Surface), but the light guide plate 31 has microparallel prism protrusions (not shown) extending in a direction perpendicular to the linear lamp 32 on its rear surface (lower surface shown in FIG. 16). The first and second arrays of microparallel prism protrusions of the light guide plate 31 of this embodiment are formed in a similar manner to those formed on the light guide plate 11 shown in FIG. The light incidence surface 31a extends perpendicular to the rear surface 31d of the light guide plate 31 facing the reflecting plate 34, and is located on the opposite side of the light guide plate 31 from the light incidence surface 31a. An end surface 31c of the substrate extends perpendicular to the rear surface 31d of the light guide plate 31. Therefore, the angle β1 between the light incidence surface 31a and the back surface 31d and the angle β2 between the end surface 31c and the back surface 31d are at right angles, and the light incidence surface 31a and the light exit surface 31b are at right angles. The angle γ1 of the liver is an acute angle, and the angle γ2 between the end surface 31c and the light exit surface 31b is an obtuse angle. Therefore, the light incident surface 31a is inclined with respect to the surface perpendicular to the light exit surface 31b. Moreover, the light incident surface 31a and the end surface 31c extend in parallel to each other. In the case of the light guide plate 31 shown in FIG. 16, the light and dark stripes (A, see FIG. 7) occur near the end of the light exit surface 31b of the light guide plate 31 (adjacent to the straight lamp 32). Can be prevented more effectively than using the light guide plate 31 shown in FIG. The angle β1 and the angle β2 may be obtuse angles and acute angles as long as the light incident surface 31a and the end surface 31c extend in parallel with each other.

Hereinafter, Examples 1 and 2 in which the surface lighting devices of the above-described second and fourth embodiments are implemented, respectively, will be described.

[Example 1]

In Example 1, the light guide plate 31 shown in Fig. 6 in which the microparallel prism protrusions of the first and second arrays are formed is used, and the reflector 35 shown in Fig. 17 in which the abnormal light shield 139 is provided is used. The light guide plate 31 is made of a transparent acrylic resin and has a substantially wedge-shaped cross section by injection molding, and has a thickness different from the thickness at one end of the light guide plate 31 (the end at which the light incident surface 31a is formed). The end face 31c is formed as a 14.1 inch diagonal plate having a thickness of 2.4 mm and 1.0 mm, respectively. The inner angle α of the apex of each prism protrusion of the first array of prism protrusions formed on the light exit surface 31b so as to extend parallel to the linear lamp 32 is set to 174 degrees, while perpendicular to the linear lamp 32 The inner angle β of the apex of each prism protrusion of the second array of prism protrusions formed on the light exit surface 31b to extend in one direction is set to 130 degrees. The pitch S of the prism protrusions of each array of the first and second arrays is set to 30 탆. Each prism protrusion of the first and second arrays is formed on the light guide plate 31 as a diamond cutting tool. A cold cathode fluorescent lamp (CCFL) serving as a linear lamp 32 is located facing the light incident surface 31a formed on the long side (long side) of the light guide plate 31.

The high brightness reflective sheet made by TSUJIDEN Co., Ltd. serves as the reflective sheet 34 (see Fig. 6) and is located under the light guide plate 31. A tubular reflector 35 having a diffusion sheet (trade name "ALSET") manufactured by MITSUBISHI PLASTICS, INC. Adhered to its inner surface is positioned around a straight lamp 32.

These components (light guide plate 31, linear lamp 32, reflective sheet 34 and tubular reflector 35) are mounted on a suitable frame member (not shown). On the other hand, a prism sheet manufactured by MITSUBISHI RAYON CO., LTD. And used as a prism sheet 33 with a cabinet of 65 degrees (α, see FIG. 10B) is a prism sheet (trade name "DIA ART": product number M165). Ridges of the projections are mounted on the light guide plate 31 so as to face the light exit surface 31b of the light guide plate 31 and extend in a direction parallel to the linear lamp 32.

Example 1 of the surface lighting apparatus having the above-described structure is compared with Comparative Example 1, which is a second side of the microparallel prism protrusions 11b in which the rear surface of the light guide plate 31 of Comparative Example 1 is shown in FIG. Same as Example 1 except that it is formed as a flat surface having no array of microarray prism protrusions corresponding to the array.

FIG. 15 shows the luminance or luminous intensity (center luminous intensity) and half-width distribution angle of luminous intensity at the center of the light guide plate 31 in Example 1 and Comparative Example 1. FIG. As shown in FIG. 15, the center luminance of Example 1 is greater than that of Comparative Example 1, but the FWHM of Example 1 is smaller than that of Comparative Example 1. FIG.

Further, fine glass beads are formed as a mat surface so that the light incident surface 31a is used as a diffused surface where light incident on the light incident surface is scattered, so that fine glass beads are light incident surface 31a of the light guide plate 31 of Example 1. Is shot against The center line average height Ra of the light incidence surface 31a is measured at 0.7 mu m by a surface roughness tester manufactured by TOKYO SEIMITSU CO., LTD. The linear lamps 32 of each of the surface lighting devices are turned on so as to know if the contrast stripes (A, FIG. 7) occur for these two surface lighting devices (Example 1 and Comparative Example 1). Visual observations were made at. As a result, the light and dark stripes A are hardly seen in the example, while the light and dark stripes A are clearly seen in Comparative Example 1. FIG.

[Example 2]

Example 2 of a surface lighting apparatus having the same structure as Example 1 is prepared except that Example 2 further includes serrated portions 337 (see FIGS. 12A and 12B). As shown in FIG. 12B, the width of each prism portion (ie, the length of the base 337c of each prism portion) of each serrated portion 337 in a direction parallel to the axial direction of the linear lamp 32. Is set to 30 占 퐉, and the width of each of the two serrated portions 337 is set to approximately 5 mm. Each serrated portion 337 is formed integrally with the light guide plate by molding.

The light guide plate 31 having a substantially wedge-shaped cross section has a thickness of one end of the light guide plate 31 (the end on which the light incident surface 31a is formed) and the thickness of the other end (the end on which the end surface 31c is formed), respectively. It is formed as a 14 inch diagonal board to be 2.4 mm and 1.0 mm. Angle β1 between the light incident surface 31a and the back surface 31d, angle β2 between the end surface 31c and the back surface 31d, angle γ1 between the light incident surface 31a and the light exit surface 31b. The angle γ2 between the end surface 31c and the light exit surface 31b is set to 90 degrees, 90 degrees, 89.58 degrees and 90.42 degrees, respectively. Therefore, the angle η1 between the light incident surface 31a and the plane perpendicular to the light exit surface 31b shown in FIG. 16 is 0.42 degrees, and is perpendicular to the end surface 31c and the light incident surface 31b shown in FIG. The angle? 2 between one surface is also 0.42 degrees.

Visual observation was made with respect to example 2 of the surface lighting apparatus having the linear lamp 32 so that the dark portions B (see FIG. 7) could be seen if they occurred. As a result, the dark portions B are hardly visible at the two corners of the light guide plate 31 which respectively face opposite ends of the straight lamp 32 in Example 1.

Example 2 of the surface lighting apparatus having the above-described structure is compared with the comparative example (comparative example 2) of the surface lighting apparatus, and this comparative example 2 has an angle β1 between the light incident surface 31a and the back surface 31d. , The angle β2 between the end surface 31c and the rear surface 31d, the angle γ1 between the light incident surface 31a and the light exit surface 31b, and the angle between the end surface 31c and the light exit surface 31b ( Except that the light guide plate 31 is formed such that gamma 2) is set to 89.58 degrees, 90.42 degrees, 90 degrees and 90 degrees, respectively, it is made to be the same as Example 2.

The luminance distribution was measured for these two surface lighting devices (Example 2 and Comparative Example 2). An intensity distribution measuring system made by HI-LAND CO., LTD. Was used for this measurement. Screen of the surface lighting apparatus in a direction perpendicular to the linear lamp 32 to measure the luminance distribution at intervals of 0.1 mm (one pixel) while the CCD camera of the intensity distribution measuring system is in the close-up position. Measurements were made at points formed towards the center of.

FIG. 18 is a graph showing a change in intensity of light emitted from the light guide plate 31 of Comparative Example 2 due to a change in distance from the light incident surface 31a. FIG. 19 is a graph similar to that shown in FIG. 18, showing a change in the intensity of light emitted from the light guide plate 31 of Example 2 due to a change in distance from the light incidence surface 31a. As can be clearly seen from the graph shown in FIG. 18, the light intensity (luminosity) drops sharply to approximately 1000 mW / m 2 at a point approximately 8 mm from the light incident surface 31a of Comparative Example 2. As shown in FIG. However, as can be clearly seen from the graph shown in Fig. 19, the light intensity at the same point of Example 2 is only dropped to approximately 1300 mW / m 2, and the intensity at a specific point is improved. Furthermore, when comparing the two graphs shown in FIGS. 18 and 19, the line of the graph shown in FIG. 19 is changed more gently than the line of the graph shown in FIG. 18, so that Example 2 of the surface lighting device has better luminance distribution than Comparative Example 2. It is clear. The “tongue portion” shown in each of the graphs of FIGS. 18 and 19 represents the portion on the light exit surface 31 covered by the front tongue portion 35b of the reflector 35.

Apparently, modifications may be made to the specific embodiments of the invention described herein, and such variations are within the spirit and scope of the claimed invention. It is to be understood that all matter contained herein is illustrative and does not limit the scope of the invention.

As can be seen from the foregoing, according to the present invention, there is obtained a surface lighting apparatus for illuminating the LCD panel as a whole with less unevenness in luminance distribution. In addition, according to the present invention, a surface lighting apparatus having a high brightness which improves the quality of images displayed on the LCD panel is obtained.

Claims (32)

A light guide plate having a light incident surface formed on one end surface of the light guide plate and a light exit surface formed on the front surface of the light guide plate; An elongated light source facing the light incident surface; A light reflector reflecting light emitted from the elongated light source toward the light incident surface; An array of microparallel prism protrusions formed on one surface of the prism sheet, and the prism sheet positioned such that the array of microparallel prism protrusions faces the light exit surface; A regular reflecting reflector positioned to face the backside of the light guide plate; A light guide guiding light emitted from the elongated light source to each of two portions of the light incident surface that respectively face opposite ends of the elongated light source; And And a diffuser formed on the light incident surface and including a diffuser for diffusing the incident light. The surface illuminating device of claim 1, further comprising a diffuse reflector formed on the specular reflector to diffuse a portion of light incident on the specular reflector. The surface lighting apparatus of claim 1, wherein the light incidence surface is inclined with respect to a plane perpendicular to the light emission surface. The method of claim 1, wherein the light guide plate, A first array of fine parallel prism protrusions formed on one of the front surface and the rear surface of the light guide plate so as to extend in a first direction; And And a second array of fine parallel prism protrusions formed on the other of the front and rear surfaces of the light guide plate so as to extend in a second direction perpendicular to the first direction. The light guide plate of claim 1, wherein the light guide plate has a substantially wedge-shaped cross section. The thickness of the light guide plate is gradually reduced in a direction away from the light incident surface, And a first angle between the light incident surface and the light exit surface of the light guide plate and a second angle between the light incident surface and the back surface of the light guide plate are one of an acute angle, a right angle, and an obtuse angle, respectively. 6. The surface illumination apparatus according to claim 5, wherein the light incidence surface formed on the one end surface of the light guide plate and the other end surface of the light guide plate located on the opposite side of the light guide plate from the light incidence surface are parallel to each other. The surface illuminating device of claim 1, wherein the light reflector comprises a second diffuser for diffusing light emitted from the elongated light source. The light guide plate of claim 1, wherein the light reflector prevents light emitted from the elongated light source from entering the light exit surface from a front side thereof, and further, other light emitted from the elongated light source is from the rear side of the light guide plate. Surface lighting apparatus comprising an abnormal light shield to prevent incident to the back of the. The method of claim 8, wherein the abnormal light shielding unit Front and rear tongue portions integrally formed with the light reflector so as to extend along the light exit surface and the back surface of the light guide plate in a direction away from the elongated light source; And And front and rear low reflectivity regions respectively positioned between the front portion and the light exit surface of the light guide plate and between the back tongue portion and the back portion of the light guide plate. 10. The surface lighting apparatus of claim 9, wherein the front and back bottom reflectance regions are formed on the front and back tongues, respectively. The surface lighting apparatus of claim 1, wherein the light guide includes two light guide members fixed to the opposite ends of the elongated light source to respectively surround two electrode portions formed at the opposite ends of the elongated light source. 12. A surface lighting apparatus according to claim 11, wherein each of said two light guide members is formed as a cylindrical lid fitted to a corresponding one of said electrode portions. The light guide according to claim 1, wherein the light guide includes two inclined surface portions formed in the light incident surface at opposite ends of the light guide, near two electrode portions respectively formed at the opposite ends of the elongated light source, Wherein each of the two inclined surface portions is inclined with respect to the elongated light source to gradually approach a corresponding one of the electrode portions in a direction away from the central surface portion of the light incident surface. The light guide according to claim 1, wherein the light guide includes two arc-shaped surface portions formed at opposite ends of the light incident surface of the light guide, near two electrode portions respectively formed at the opposite ends of the elongated light source, And each of the two arc-shaped surface portions is bent to gradually approach a corresponding one of the electrode portions in a direction away from the central surface portion of the light incident surface. The light guide according to claim 1, wherein the light guide is At least one first surface on which a portion of the light emitted from the elongated light source is incident; And And at least one second surface for reflecting the light incident on the at least one first surface to advance toward the inside of the light guide plate. The surface lighting apparatus of claim 15, wherein the at least one first surface is angled at an angle of about 40 to 55 degrees with respect to the at least one second surface. The plurality of first surfaces and the plurality of second surfaces of claim 15, wherein the at least one first surface and the at least one second surface form two serrated portions at opposite ends of the light incident surface. Surface lighting equipment, each of which constructs surfaces. The surface illuminating device of claim 15, wherein each of the at least one first surface and the at least one second surface is formed as a mat surface. The surface illuminating device according to claim 1, wherein said light incident surface is formed as a mat surface. 20. The surface illuminating device according to claim 19, wherein the median average surface height of said mat surface is in the range of 0.4 mu m to 1.0 mu m. The surface illuminating device of claim 1, wherein the prism sheet comprises an abnormal light shield for preventing the light emitted from the elongated light source from being incident on the light incident surface from its front surface. 22. The method of claim 21, wherein the prism sheet is slightly moved in a direction away from the light incident surface with respect to the light guide plate so that a predetermined space is formed between the light shielding strip and the light exit surface, The abnormal light shield includes a light shielding strip positioned above the predetermined space so as to extend from one end of the prism sheet facing the elongated light source. 23. The width of the space between the light incidence plane and the one end of the prism sheet in a direction perpendicular to the longitudinal direction of the light incidence plane and parallel to the light exit plane. Surface lighting apparatus within the range of. 2. The light guide plate according to claim 1, wherein each of the light guide plate and the specular reflector is formed as a rectangular plate, And the diffuse reflector comprises two diffuse reflecting surfaces each formed at two corners facing the opposite ends of the elongated light source in front of the specular reflector. 25. The ink according to claim 24, wherein each of the two diffuse reflection surfaces is printed on the front side of the specular reflector such that the degree of light diffusion of the diffuse reflection surface is reduced toward the center of the front side of the specular reflector. And a printing pattern, wherein the ink having a high diffuse reflectivity is used to print the ink printing pattern. The surface illuminating device of claim 1, wherein the diffuse reflector comprises a diffuse reflecting surface formed on a front surface of the specular reflector such that the elongated light source extends parallel to the elongated light source along one side of an adjacent specular reflector. 27. The inkjet printed pattern of claim 26, wherein the diffuse reflection surface includes an ink print pattern printed on the front surface of the specular reflector such that the degree of light diffusion of the diffuse reflection surface increases toward the specular reflector adjacent to the elongated light source. And an ink having a high diffuse reflectivity is used to print the ink print pattern. A light guide plate having a light incident surface formed on one end surface of the light guide plate and a light exit surface formed on a front surface of the light guide plate; And An elongated light source facing the light incident surface, And the light incidence plane is inclined with respect to a plane perpendicular to the light exit plane. The method of claim 28, wherein the light guide plate A first array of fine parallel prism protrusions formed to extend in a first direction from one of a front surface and a rear surface of the light guide plate; And And a second array of fine parallel prism protrusions formed so as to extend in a second direction perpendicular to a first direction from one of the front side and the rear side of the light guide plate. The light guide plate of claim 28, wherein the light guide plate has a substantially wedge-shaped cross section. The thickness of the light guide plate is gradually reduced in the direction away from the light incident surface, And a first angle between the light incident surface and the light exit surface of the light guide plate and a second angle between the light incident surface and the back surface of the light guide plate are one of an acute angle, a right angle, and an obtuse angle, respectively. 31. The surface illumination apparatus according to claim 30, wherein the light incidence surface formed on the one end surface of the light guide plate and the other end surface of the light guide plate located on the opposite side of the light guide plate from the light incidence surface thereof are parallel to each other. The surface illuminating device of claim 4, wherein the first direction is parallel to an axial direction of the elongated light source.