JPH0634141B2 - Surface light source - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface light source device used for a liquid crystal backlight, a lighting display, a lighting sign, a lighting body, and the like.

[Conventional technology]

A surface light source device of this type has been proposed and put into practical use in place of an internally-illuminated light source device that performs back illumination by vertically or horizontally installing a large number of fluorescent lamps on the back side of a transparent panel.

The surface light source device is such that a light source such as a fluorescent lamp is disposed in close proximity to one or a plurality of end surfaces of the surface light source panel, and the light source light is incident and supplied from the end surface into the surface light source panel, and the entire surface light source panel is provided. The illumination should be as bright and uniform as possible. Generally, a surface light source panel forms minute point-shaped or linear irregular reflection surfaces by screen printing or shot blasting with various inks such as white ink, light density ink, etc. on a transparent resin substrate with high light transmittance such as acrylic, and this irregular reflection It is designed to emit and guide incident light by irregular reflection by the surface, and at this time, the surface light source panel is a single plate,
Alternatively, a plurality of laminated layers are used, a reflection tape is provided on the end surface other than the light source, and a reflection surface such as a reflection film or a reflection plate is arranged on the back surface of the non-illumination side of the one-sided illumination. Is done more effectively.

[Problems to be Solved by the Invention]

This seed surface light source device has the merit that it can be made thinner than the above-mentioned internal illumination type device, and has various improvements to improve the brightness.
One side light source using a single surface light source panel of 65 × 255 mm with a brightness of, for example, 1,000 cd / m ² or more, and a surface light source panel of four A4 size laminated for a double-sided display, facing end Of multiple light sources,
It is supposed that a brightness of about 1,500 cd / m ² can be realized.

However, at present, the liquid crystal backlight as this kind of surface light source device is exclusively used for monochrome, and in such a case, it can withstand practical use with the above-mentioned brightness, and as in the above-mentioned double-sided display, such as stacking of surface light source panels and opposite ends. This can be improved by using multiple light sources. However, for example, when the liquid crystal display surface is used for color, it is required to further improve the brightness (for example, 2,000 cd / m ² or more). In any case, the brightness of the current surface light source device is insufficient, and further, in other surface light source devices such as a display, further improvement in brightness is required.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an improved surface light source device in which the brightness is further improved as much as possible in the relationship between the surface light source panel and the light source. .

[Means for Solving the Problems]

As a result of earnest research in accordance with the above-mentioned object, the present inventors have established a separation space facing an end light source between a plurality of laminated surface light source panels or between a surface light source panel and a facing reflection surface facing the surface light source panel. It is also possible to dispose the bulging surface or the inclined surface of the surface light source panel in the separated space in a protruding manner.
Furthermore, in these cases, it was found that it is extremely effective to improve the brightness by arranging a plurality of light sources such as fluorescent lamps in parallel in the thickness direction.

The present invention has been made on the basis of such findings, and in the present invention, in addition to guiding the incident light from the end face to the surface light source panel, the in-plane position to be separated from the light source of the surface light source panel. In the above, the technical idea is further included in that the direct light from the light source is supplementarily incident and supplied, that is, the present invention is between a plurality of surface light source panels or between a surface light source panel and a facing reflection surface. A surface light source device (claim 1), characterized in that a separation space facing the end light source is interposed, and a bulging surface or an inclined surface of the surface light source panel is additionally provided in the separation space according to claim 1. A surface light source device (claim 2), characterized in that the bulging surface or the inclined surface faces the end light source in the separated space.
The surface light source device according to claim 1 or 2, wherein a plurality of the end light sources are arranged along the longitudinal direction of the surface light source panel and the end face of the separated space and arranged in parallel in the thickness direction thereof (claim 3). Section) and these are the main points of each.

[Work]

According to the present invention, the light source light is incident on the separated space facing the end light source at one end or a plurality of ends, so that the light source light is directly supplemented to the surface light source panel at an intermediate position in the plane. And contributes to the improvement of the brightness in combination with the incident light that is diffused and reflected from the end face and guided.

In the first aspect, the light source light in the separated space is supplied to the surface light source panel through diffused reflection in the air, and in the second aspect, the light source light is further extracted from the bulging surface or the inclined surface. The luminance is improved by being efficiently and directly supplied to the surface light source panel, and in the third aspect, by dramatically increasing the light amount of the end light source with respect to the surface light source panel and the separated space. To achieve.

〔Example〕

The present invention will be further described below with reference to the drawings. FIG. 1 shows an example of a surface light source device that can be used for various purposes.
FIGS. A to N show the arrangement state of the surface light source panel or the anti-slope and the separated space in Examples 1 to 10 and Comparative Examples 1 to 5 described later,
3A to 3C show another example of the arrangement of the surface light source panel and the separated space.

In FIG. 1, the surface light source device 1 includes a display section (not shown) (for example, a display film in a display device and a protective transparent panel or word processor provided as necessary, a liquid crystal display surface and a protective transparent panel in a television receiver). Is provided on the back side of the device, for example, in the illustrated one-side illumination type, from the display side, the white polyester diffusion film 2, the flat surface light source panel 3, and the flat surface light source panel 3 side bulging surface 5 by bending. The curved surface light source panel 4 having the above, the reflection tape 9 on the non-incident side of the surface light source panels 3 and 4, and the rear reflection film 10 are provided and arranged on the upper and lower end surface sides of the surface light source panels 3 and 4. , Light sources 11, 11 and these light sources 1 by an aperture fluorescent lamp having a transparent surface facing them
The light source reflection films 12 and 12 are provided so as to cover the light sources 11 and 11 on the non-incident side that does not face the surface light source panels 3 and 4.

Between the flat surface light source panel 3 and the curved surface light source panel 4 facing the flat surface light source panel 3, the total dimension of the bulging dimension due to the bending of the curved surface light source panel 4 and the slightly spaced center panel dimension is used as a reference. A distant space 8 is provided, and in this example, the bulging surface 5 of the curved surface light source panel 4 is disposed in a protruding manner in the distant space 8, whereby the bulging surface 5 causes the end light source 11, 11 are opposed to each other.

Each of the surface light source panels 3 and 4 is provided with a diffuse reflection surface 7 over the entire rear surface side of a transparent resin substrate 6 made of acrylic, for example, which has a high light transmittance. On the substrate 6, the area ratio is increased stepwise in the range of 25 to 65% in parallel in the in-plane direction away from the upper and lower light sources 11, 11 and the maximum is obtained at the upper and lower central positions farthest from the light sources 11, 11. The halftone dot patterns respectively configured to have the ratio are provided, and thereby the uniformity of the brightness is ensured.

Although the irregular reflection surface 7 is formed by screen printing, in the screen printing of this example, a light-concentration ink having a solid content ratio of about 13 to 30 wt% and a fluorescent pigment added thereto is used instead of the normal white ink. As a result, each halftone dot portion forming the irregular reflection surface 7 is made to be transparent to light so that it can shine brighter than itself (for the formation of these irregular reflection surfaces, see Japanese Patent Application No. 63-208670). JP-A-02-126501).

On the other hand, each of the reflection film 10 and the light source reflection film 12 is a thin film obtained by low-foaming white polyester, and the anti-slope to the surface light source panels 3 and 4 and the light sources 11 and 11 is a foamed surface of the polyester. By forming this reflective surface as a foamed surface, it is possible to improve the brightness by about 10% as compared with the case where a non-foamed homogeneous white polyester film is used.

For example, in the surface light source device embodied as described above, the interposition of the separation space and the protruding arrangement of the bulging surface or the inclined surface of the surface light source panel into the separation space are shown in the following embodiments. As such, and further, as will be described below, they can be various.

Example 2 Two 3 mm thick flat surface light source panels of A4 size were used, and a 6 mm separation space corresponding to two panels was provided between these panels as shown in FIG. This is arranged horizontally, and aperture fluorescent tubes with a light source brightness of 34,500 cd / m ² are arranged at the left and right ends (corresponding to the upper and lower ends of the above-mentioned example), respectively, and the surface light source panel and the separated space are provided. The incident light was supplied, and the luminance at 9 points on the upper surface side in the figure was measured (using the Minolta luminance meter LS-110) and the average luminance was obtained.

It should be noted that the reflective sheet was used as compared with the example shown in the figure, but the light source reflective sheet was not used.

The brightness at this time is shown in Table 1.

As a result, the average surface luminance is 1,805 cd / m ² , and it is known that the luminance can be improved by stacking layers. Compared with Comparative Example 1 described later using three flat surface light source panels. Even so, a brightness improvement of 18.3% is seen.

Example 2 Example 3 was the same as Example 1 except that three flat plate light source panels were used, and a space for separating one panel from each other was arranged as shown in FIG. 2B and the upper surface side in the figure was measured.

The luminance at this time is shown in Table 2.

As a result, the surface average luminance was 1,714 cd / m ² , and similarly, a luminance improvement of 12.3% was observed.

Example 3 The same arrangement as in Example 2 was turned upside down and the luminance on the upper surface side in the figure was measured as shown in FIG. 2C.

The luminance at this time is shown in Table 3.

As a result of the above, the surface average brightness is substantially the same as that of the second embodiment.
At 13 cd / m ² , similarly, a brightness improvement of 12.3% was observed.

Example 4 Using two flat plate surface light source panels and one curved surface light source panel, the surface light source panel and the separated space and the bulging surface protruding into this separated space are arranged as shown in FIG. 2D. Same as Example 1 except that the upper surface side in the figure was measured.

The luminance at this time is shown in Table 4.

As a result of the above, the surface average luminance was 1,805 cd / m ² , and similarly a luminance improvement of 18.3% was obtained.

Example 5 The same arrangement as in Example 4 was turned upside down, and the luminance on the upper surface side in the figure was measured as shown in FIG. 2E.

The brightness at this time is shown in Table 5.

As a result, the surface average luminance was 1,786 cd / m ² , and similarly a luminance improvement of 17.1% was obtained.

Example 6 Example 6 was the same as Example 4 except that the arrangement of the surface light source panel, the separation space, and the bulging surface was as shown in FIG. 2F.

The brightness at this time is shown in Table 6.

As a result, the surface average brightness was 1,724 cd / m ² , and a brightness improvement of 13% was similarly obtained.

Example 7 The same arrangement as in Example 6 was turned upside down, and the luminance on the upper surface side in the figure was measured as shown in FIG. 2G.

The brightness at this time is shown in Table 7.

As a result, the surface average luminance was 1,729 cd / m ² , and similarly a 13.3% improvement in luminance was obtained.

Example 8 Using one flat surface light source panel and one curved surface light source panel,
Same as Example 1 except that the arrangement was as shown in FIG. 2H.

The luminance at this time is shown in Table 8.

As a result, the surface average luminance was 1,773 cd / m ² , and similarly, the luminance improvement of 16.2% was observed.

Example 9 The same arrangement as in Example 8 was turned upside down and the luminance on the upper surface side in the figure was measured as shown in FIG. In this case, it corresponds to the example shown in the figure.

The brightness at this time is shown in Table 9.

As a result of the above, the surface average luminance was 1,840 cd / m ² , and similarly a 20% improvement in luminance was observed.

Example 10 Except that two flat plate light source panels and a reflection sheet were used, and a space of 3 mm for one panel was provided between the laminated panel and the reflection sheet, as shown in FIG. 2J. Same as Example 1.

The luminance at this time is shown in Table 10.

As a result, the average surface luminance is 1,349 cd / m ^2, which is 3
It is inferior to Comparative Example 1 using a single panel, but 35 against Comparative Example 5 in which two panels and a reflection sheet are laminated.
% Improvement in brightness was observed.

Comparative Example 1 The same as Example 1 except that three flat plate light source panels were stacked as shown in FIG. 2K.

The brightness at this time is shown in Table 11.

As a result, the average surface luminance was 1,525 cd / m ² .

Comparative Example 2 The same as Example 1 except that four flat plate light source panels were stacked as shown in FIG. 2L.

In this case, the total thickness is the same as in Example 1.

The brightness at this time is shown in Table 12.

As a result, the luminance was 1,704 cd / m ² , and the stacking effect of the fourth panel was exhibited.
A 7% improvement in brightness was observed.

Comparative Example 3 Two flat plate light source panels and one curved surface light source panel are used, and as shown in FIG. 2M, the curved surface light source panel forms a separation space facing the light source, contrary to the above embodiment. The same procedure as in Example 1 was carried out except that the elements were arranged without any special arrangement.

The brightness at this time is shown in Table 13.

As a result of the above, the luminance was 1,477 cd / m ² , and Comparative Example 1
Also, the luminance decrease of -3.2% was observed.

Comparative Example 4 The same arrangement as in Comparative Example 3 was turned upside down, and the luminance on the upper surface side in the figure was measured as shown in FIG. 2N.

Table 14 shows the luminance at this time.

As a result of the above, the luminance was 1,531 cd / m ² , and Comparative Example 1
Comparative example 5 Two flat plate light source panels and a reflection sheet were used, and they were laminated without a space between them, and as shown in FIG. Was measured.

The brightness at this time is shown in Table 15.

As a result, the brightness was 999 cd / m ² .

The above-mentioned Examples 1 to 3 and 10 correspond to the first claim,
Examples 4 to 9 correspond to claim 2, but 10 to 2 for the comparative examples carried out under the same or more advantageous conditions.
It can be seen that the surface average brightness is improved by about 0%.

The brightness at 9 points on each coordinate axis also tends to exceed the comparative example.

Further, although the comparative example 2 and the examples 2 and 3 cared for the surface light source panel, there is a difference in whether or not a separated space for one panel is provided, but the brightness is 1,700 cd / The results are almost the same at m ^{2 or} more, and it is clear that this separated space has the effect of improving the brightness by stacking the surface light source panels, and comparing these with Example 1 It can be said that it is more effective to improve the brightness by removing one more surface light source panel and expanding the separated space.

On the other hand, according to the fourth to ninth embodiments, the illumination surface is flattened by the flat surface light source panel, and the separation space is provided between the flat surface light source panel and the flat surface light source panel. It is possible to project the bulge surface so as to face the end light source.
It is shown that it is more effective than the curved surface from the viewpoint of improving the brightness.

By the way, in Examples 4 to 7, there is a tendency that the variation in luminance at each position of the coordinate axis is larger than that in Examples 1 to 3 (or as compared with Comparative Examples 1 and 2). All of these use a curved surface light source panel having a bulging surface, but this variation is due to forming the irregular reflection surface on the entire surface of the curved surface light source panel, eliminating the variation, and In order to make the brightness uniform, a diffuse reflection surface is not provided in the vicinity of the light source, or a pattern in which this is greatly densified is used, while the diffuse reflection surface is provided as the distance from the light source is increased and the density is sequentially increased as in the illustrated example. By doing so, it is naturally possible to prevent the reduction of the average surface luminance and to make it uniform by adjusting the irregular reflection surface.

By the way, in the practice of the present invention, the bulging surface bends the surface light source panel, and as shown in FIGS. 3A and 3B, the surface light source panel 13 is formed into a convex lens shape on the one side bulging surface 5 and the other side flat surface. In addition, both can be bulged surfaces 5 and 5, and an inclined surface is provided instead of the bulged surface. In this case, when the one-side light source is used, the inclined surface is flush with the non-light source side. It can be understood from the above description that the above can be formed.

Further, regarding the relationship between the surface light source panel and the separated space, as shown in FIG. 3C, the surface light source panels 14 and 14 having the same inclined surfaces 15 and 15 (or the bulging surface and the concave surface) are opposed to each other. It is possible to provide an inclined (or curved) separated space 16 in between. The surface light source panel in this case is obtained by injection molding, for example.

Further, in the above example, a single light source is used on one side, but in order to sufficiently supply the incident light to the surface light source panel and the separated space, the light sources are arranged in parallel with each other in the longitudinal direction of these end faces and in the thickness direction. It is possible to arrange a plurality of light sources such as a book.
FIG. 3D shows an example using these two light sources,
The surface light source panel 15 has a concave surface like a concave surface on one side and a flat surface on the other side. A space is provided between the surface light source panel 15 and the reflecting film 10 similar to the above, and two light sources 11 are arranged on the respective end surface sides. The two light sources 11 cover the end face thickness direction sufficiently. The plurality of light sources may be arranged in each of the illustrated examples. In this case, Japanese Patent Application No. 1-3418 may be used.
If the cold cathode tube disclosed in No. 00, which has a small diameter (3 to 8 mm), can obtain high brightness and generates less heat in the electrode portion,
Further, the thickness and the dimensions of the plurality of light sources can be adjusted, which is convenient.

In order to improve the brightness as a matter of course, the light source can be arranged not only on one side or the opposite side of the surface light source panel but also on the three end faces and further on the entire circumference.

Further, in the above-mentioned example, the irregular reflection surface of the surface light source panel has a halftone dot pattern of parallel stepless increase and decrease. However, when forming the irregular reflection surface, as shown in Japanese Patent Application No. 1-256820, By providing the adjustment pattern portion in which the area ratio is reduced in a mountain shape on the side, the uniformity of brightness can be improved. Further, in the screen printing, as shown in the patent application by the applicant of the present application dated March 6, 1990, by mixing fine hollow particle portions due to foaming or resin hollow powder in the printing ink, 10% is obtained. The brightness can be improved to some extent. On the other hand, instead of providing the reflective tape on the non-light source side of the surface light source panel in the above-mentioned example, as shown in the patent application by the applicant of the present application dated February 27, 1990, By making the end surface on the non-light source side a mirror-like smooth surface, the brightness can be similarly improved.

Therefore, the implementation of the present invention, as described above, is 10 to 20%.
Since it is possible to improve the brightness of, by using these together,
It is possible to achieve a greater brightness improvement.

Although the illustrated and described embodiments are as described above, in the implementation of the present invention, the application of the surface light source device, the surface light source panel, the separated space, the bulging surface, the inclined surface, each specific configuration of the light source,
Regarding the shape, dimensions, addition of other parts, etc., it is naturally possible to make various changes as long as they do not violate the gist of the above-mentioned occurrence, and to apply known conventional means for the changes.

〔The invention's effect〕

Since the present invention is configured as described above, by providing a separation space facing the end light source between the plurality of surface light source panels or between the surface light source panel and the opposing reflection surface, further, in this separation space. By disposing the bulging surface or the inclined surface of the surface light source panel in a protruding shape and facing the end light source, it is possible to achieve a brightness improvement of about 10 to 20% or more, respectively. It is extremely effective for increasing the brightness of the surface light source device.

Furthermore, by providing a separated space, it is possible to reduce the relative weight in both cases, which is suitable for both single use and incorporation into other equipment, and it is possible to achieve cost reduction depending on the mode. Is.

Further, since the present invention has a relatively simple structure, it can be implemented by improving the conventional one, while providing a surface light source device excellent in durability without trouble or deterioration.

Further, in addition to the above, according to the third aspect, the brightness can be further improved, which is convenient for increasing the brightness of the surface light source device.

[Brief description of drawings]

The drawings show embodiments, FIG. 1 is an exploded perspective view of a surface light source device, and FIGS. 2 (A) to 2 (O) are arrangement examples of a surface light source panel and a separation space, respectively. 3A to 3D are model cross-sectional views corresponding to the respective arrangements of Comparative Examples 1 to 5, and FIGS. 3A to 3D are model cross-sectional views showing another example of the surface light source panel and the separated space. 1 ... surface light source device, 5 ... bulging surface 3,4,13,14,15 ... surface light source panel 8,16 ... separated space, 11 ... light source

Claims (3)

[Claims] 1. A surface light source device comprising a plurality of surface light source panels, or between the surface light source panel and a facing reflection surface, with a separation space facing the end light source interposed. 2. A bulging surface or an inclined surface of the surface light source panel is additionally provided in a protruding manner in the separated space of claim 1, and the bulged surface or the inclined surface is opposed to the end light source in the separated space. A surface light source device characterized by being at least as small as possible. 3. The end light source according to claim 1 or 2,
A surface light source device comprising a plurality of surface light source panels and a plurality of them arranged in parallel in the thickness direction along the longitudinal direction of the end face of the separated space.