JPH03256090A - Face light source unit - Google Patents

Abstract

PURPOSE:To obtain high brightness as much as possible by providing an edge light face light source panel which has fine hollow particle parts dispersed by foaming in an ink vehicle on an irregular reflecting surface formed on one side surface by screen printing. CONSTITUTION:A thin transparent resin substrate 10 made of acryl is used for the edge light face light source panel 9 and the irregular reflecting surface 11 is formed by screen printing entirely on one side surface, i.e. the front surface on the side of a diffusion file 8. The irregular reflecting surface 11 is formed by printing and sticking ink which contains a foaming agent on the transparent resin substrate 10 by screen printing, heating and foaming the ink, and drying and setting the ink. The irregular reflecting surface 11 have fine hollow particle parts 15 in independent air bubble shapes dispersedly in the ink vehicle 14. Consequently, the reflection of incident light which is refracted to travel in the face light source panel is accelerated more than before and the brightness is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface light source device used in various surface light source devices such as liquid crystal backlights, illumination displays, illuminated signs, and lighting bodies.

[Prior Art] The edgelight surface light source panel in this type of surface light source device has a diffused reflection surface such as minute dots formed by screen printing on one side surface of a transparent resin substrate with good light transmittance, such as acrylic. When used as a surface light source device, a reflective surface made of a white polyester sheet or a reflective film made of a silver vapor-deposited sheet is arranged in a layered manner on one side surface of this surface light source panel, and the end surface of the surface light source panel is It is said that incident light is supplied by a light source of a fluorescent lamp installed facing along the surface of the panel, causing the surface light source panel to emit light.

A diffused reflection surface formed by screen printing can be obtained by using an ink that remains translucent, for example, as shown in Japanese Patent Application No. 63-208670 proposed by the present inventors, and printing a surface separated from a light source on the surface of an example of a transparent resin substrate. A dot pattern of 42.5 cotton with a stepless change inward and an area ratio of 20 to 60% is used to cover almost the entire surface of the ink. In order to improve the
Commercially available reflective glass beads having a particle size of about 100 ml are added and mixed in the ink vehicle.

[Problem to be Solved by the Invention 1] Today, surface light source devices are attracting attention for their use as liquid crystal backlights built into electronic devices such as computers, and the demand for them is increasing.

However, when built into other equipment, there is an increasing demand for the surface light source device to be more compact. It has become necessary to improve the edge light surface light source panel and the light source on one end side to provide sufficiently high brightness and uniformity.

Furthermore, in order to use this liquid crystal backlight in equipment with a color liquid crystal display surface such as a liquid crystal color television receiver, the conventional brightness described above is not necessarily sufficient, and a dramatic improvement in brightness is a prerequisite for practical use. It is said that

The present invention has been made from this point of view, and its purpose is to provide an improved surface light source device that can achieve as high brightness as possible.

[Means to solve the problem]

As a result of intensive research in line with the above objectives, we found that the diffused reflection surface is mixed with foamed fine hollow particles instead of commercially available reflective glass beads, and that the reflective surface of the reflective sheet of the surface light source panel is a foamed resin surface. Furthermore, the fact that foaming means, such as making the reflecting surface of the light source a foamed resin surface, is extremely effective in improving brightness, and the fact that the foaming means is extremely effective in improving brightness, as well as the fact that the foaming means is extremely effective in improving brightness, and by providing the diffused reflection surface with a mixture of fine hollow particle portions made of hollow resin powder, the foaming can be improved. We have discovered the fact that results similar to those obtained by

The present invention has been made based on this knowledge and with an industrial field and purpose in mind. Namely, the present invention provides an ink vehicle with a diffused reflection surface formed on the side surface by screen printing, in which fine hollow particle portions formed by foaming are mixed and provided. A surface light source device comprising an Edgelight surface light source panel (Claim 1) The fine hollow particle portion of Claim 1 is a fine hollow particle portion made of resin hollow powder instead of foaming. Characteristic surface light source device! (Claim 2) A surface light source device characterized in that the reflective surface integrally formed on the surface of an example of an Edgelight surface light source panel or arranged in a layered manner is a foamed resin surface (Claim 11, Item 3) Edgelight A surface light source device (Claim 4) characterized in that the light source reflecting surface arranged to cover the non-incident end surface side of the light source facing the incident end surface of the surface light source panel is a foamed resin surface. Each will serve as a summary.

[Function] In the present invention, a large improvement in brightness can be seen as described below, but in each of claims 1 to 3, the reflection of incident light that refracts and progresses within the surface light source panel. In the first and second claims, this contributes to the light emission and light guide of the diffused reflection surface, and in the third claim, this contributes to the inward reflection of the surface light source panel. This seems to be because it contributes to preventing the depletion of incident light due to On the other hand, in claim 4, the surface light source reflecting surface effectively reflects the light source light on the non-incident end surface side, prevents loss of the light source light amount, and reduces the light source light amount to the edge light surface light source panel as much as possible. It appears to be for the purpose of providing supplies.

[Example 1] The present invention will be further explained with reference to the drawings showing an example below. Reference numeral 1 denotes a word processor, and the word processor 1 includes a main body 2 having a keyboard section 3, and a main body 2 installed in the main body 2 so as to be able to rise and fall. and a display section 4.

The display section 4 has a transparent protection panel 5 and a liquid crystal display panel 6 from the front side, and a surface light source device 7 serving as a liquid crystal backlight is built into the back side of the liquid crystal display panel 6.

The surface light source device 7 also includes, from the front side, a diffusion film 8 made of white polyester film, an Edgelight surface light source panel 9, a reflective film 16, and one side of the surface light source panel 9 installed along the left end surface of the surface light source panel 9. single light source 17;
The light source reflecting film 18 of the light source 17 and a thin and compact inverter (not shown) are provided.

The edge light surface light source panel 9 is 165X in this example.
An acrylic transparent resin substrate 10 having an area of 225 mm and a thickness of 3 mm was used, and its − side surface, that is,
A diffused reflection surface 11 printed by screen printing is provided over the entire front surface on the diffusion film 8 side.

In this transparent resin base @ 10, the diffused reflection surface 11 has an area ratio of 20 to 20 in a stepless manner parallel to the inward direction of the plane away from the light source 17.
The parallel pattern portion 12 is varied within a range of 60% and has a maximum ratio at an intermediate position near the end of the non-light source I11 in order to eliminate non-uniformity in brightness due to reflected light, and the parallel pattern portion 12 is itself a parallel pattern. At the same time, on the light source side, a halftone dot pattern is formed by an adjustment pattern portion 13 in which the area ratio of the parallel pattern is slightly reduced, in a mountain shape having the end facing the light source as the base. This is to ensure uniformity of brightness as a whole.

For screen printing of the diffuse reflection surface 11, the solid content ratio is 13 to 3.
An ink containing a fluorescent pigment added to a pale purulent ink of about owt% is used, and in this example, a heating foaming agent (for example, azobisisobutyronitrile or microspheres) is used to foam the ink vehicle. - type foaming agent) is added.

The ink containing the foaming agent is printed and adhered to the transparent resin substrate 10 by screen printing, and then heated at 180°C.
The ink is foamed by placing it in a heated atmosphere for 2 seconds, and then about 3 portions are constantly passed through a low-temperature heating drying oven at 60 to 80°C to dry and harden the ink.

Diffuse reflection Il on the transparent resin substrate lO that has undergone such a process
l is 1.2-20μ for general ink thickness 10-20μ
The ink thickness is expanded by 1.5 times, for example, from 13 to 26 μm, and the diffused reflection layer 11 includes a mixture of fine hollow particle portions 15 in the form of closed cell particles due to foaming in the interrupter 14. leading to.

This mixed state appears to be an irregular distribution throughout the ink vehicle 14, which has a mountain shape, as shown in FIG. 3, for example.

Generally, ink containing a foaming agent is used to form surface irregularities, but by controlling the heating time and heating temperature to suppress foaming, it is possible to create a mixture of fine hollow particles. Also, by doing so, deformation and damage to the transparent resin substrate 10 can be prevented.

The Edgelight surface light source panel 9 equipped with the fine hollow particle portions 15 created by this foaming has a brightness of 490 nits, compared to the brightness of 450 nits in the conventional glass beads case, which is an approximately 10% brightness improvement. It was seen.

Note that reflective tape, which is normally used except for the light source side, is not attached to the end face of the surface light source panel 9 in this example.
The end faces of the transparent resin base 12ii10 are subjected to puff polishing and mechanical polishing to form mirror-like smooth surfaces, and wear and tear due to divergence of incident light from these end faces is effectively prevented.

On the other hand, the reflective film 16 is made of a white polyester low foam film (newly developed film lot number 010805207 manufactured by Toshi Co., Ltd.) in this example.

This low foaming film is said to have improved whiteness and reflectance due to low foaming, with a whiteness of 99% (83% for non-foamed polyester film) and a reflectance of 97%.
% (88%), and the density of this film is 0,80 g/c+++' (1,4
9g/cm"), the thickness is 18" which is the same as the non-foamed one.
It is said to be 8 μm.

This reflective film 16 is arranged in a laminated manner so as to be in close contact with the surface light source panel 9, with one side thereof being a reflective surface, so that when the incident light from the light source 17 is refracted and proceeds, Surface light source panel 9 by reflection
This is to promote inward return and effectively prevent the incident light from being wasted.

The light source reflective film 18 in this example is also made of a white polyester low-foam film, is curved to cover the non-incident end surface side of the cylindrical light source 17, and is fixedly arranged on a fixing member (not shown). A light source reflecting surface is formed on the outer periphery of the surface light source panel 9 of No. 17 other than the curved surface facing the incident end surface.

At this time, the low foam film has a thickness of 75 um and a density of 0.80 g, which is slightly different from that of the reflective film 16.
7cra”, a newly developed film lot number 010805 manufactured by Toshi Co., Ltd. with a whiteness of 101% and a reflectance of 97%.
207.

In the surface light source device 7 of this example using the light source reflective film 17 and the reflective film 16 in which the light source reflective surface 1 is a foamed resin surface, the light density is 30% compared to the conventional 505 nit.
A bright and uniform luminescent illumination of 660 nits with improved luminance was obtained.

Note that the light source 17 in this example does not use a fluorescent lamp, but instead uses a small-diameter cold cathode tube that uses a cold cathode that generates almost no heat for the electrode, which ensures a sufficient amount of incident light and a long life of the light source. We are trying to make this happen.

FIG. 4 shows fine hollow particle portions 19 in the ink vehicle 14.
Another example is shown, in which a resin hollow powder body which itself is a hollow solid is included.

This resin hollow powder body has a standard diameter of 20 μm. Hollow transparent microcapsules used for fragrances are used, and this powder is added to the ink instead of the above-mentioned foaming agent, and then screen printed on a transparent resin substrate 10,
Similarly, by drying and curing the ink in a low-temperature heating drying oven at 60 to 80° C., the ink is mixed in the ink vehicle 14.

In addition, at this time, it is preferable that the ink is applied slightly thickly during screen printing, and in such a case,
The resin hollow powder body can be made to float on the surface side to further promote diffused reflection. In addition, the addition of resin hollow powder
Generally 15-25%, preferably 2% based on the weight of the ink.
It is best to set it at about 2%.

In this example, where the fine hollow particle portion 19 is formed from this resin hollow powder, the brightness is improved by about 11% to 505 nits, compared to 450 nits when conventional reflective glass beads (43 μm diameter is standard) are added. Obtained.

On the other hand, FIGS. 5 and 6 show an example in which the surface light source device of the present invention is applied to a single-sided illuminated sign.

The illumination sign 20 is a guide character display panel 2 according to the - side front rule.
3, the backlighting is performed by a surface light source device 7, and each member is a press-molded 1, for example 1.
It is housed in a thin housing 21 with a thickness of 5-+m and an open front.

In this example, the light 11117 is housed in the upper and lower lamp houses 22 and 22 of the housing 21, respectively, so that the light source light is supplied to the edge light surface light source panel 9 from both the upper and lower sides.

For this reason, the diffused reflection surface ll in the edge light surface light source panel 9 is provided with adjustment pattern portions 13.13 similar to those described above on each light source 17.17 side, and parallel pattern portions 1
The transparent resin substrate 10 is configured such that its area is maximized at the vertical center position of the substrate 2.
It is made of transparent acrylic resin with a thickness of 1111 mm.

In addition, in this example, both the diffusion film 8 and the anti-fouling film 16 are high-frequency welded to the peripheral band-shaped portions of the Edgelight surface light source panel 9.
It is integrated with.

The light source reflection film 19 is further bonded and integrated with the upper and lower edges of the diffusion film 8 and the reflection film i6 via the adhesive tape 24, so that it curves elastically and covers the non-incident end face side of each light source 17. It's Nishide.

The remaining configurations of the surface light source device 7 are the same as in the example described above, and therefore their descriptions will be omitted.

The illustrated example is as described above, but in carrying out the present invention, it is possible that surface irregularities may be formed in part of the fine hollow particle part due to foaming, but as much as possible, this remains as a fine hollow particle part. It is considered that the presence of the fine hollow particle portions makes a greater contribution to improving the brightness of the Edgelight surface light source panel.

It is preferable to use a resin hollow powder having a diameter as small as possible, and it is preferable that the particle diameter is at least as small as possible than that of a reflective glass bead.

Resin hollow powder is lighter than glass beads and has the characteristics of being easily compatible with ink, but by doing so, it reduces the 8 to 30% reduction in clogging during screen printing when reflective glass beads are added. Printing defects that can be seen between machines can be easily resolved.

The reflective surface can also be formed integrally with the negative side surface of the transparent resin substrate by, for example, spraying a foamable resin onto the transparent resin substrate.
A foamed film or foamed board made of ABS, polyester, etc. can also be used.

Note that it is preferable to use the cold cathode tube as the light source because it provides sufficient brightness, does not require heating, and uniformly supplies incident light along the longitudinal direction of the incident end surface of the surface light source panel. Although it is easy to do so, it is also possible to further improve the brightness by using an aperture tube whose incident end surface is made of transparent glass.

As is clear from the above, when carrying out the present invention, each specific configuration of the fine hollow particle portion, foamed resin surface, Edgelight surface light source panel, etc., including the foaming rate, particle size, number of laminated sheets, and its forming means, The shape, use as a surface light source device, etc. can be variously changed as long as they do not go against the gist of the invention described above, and there is no need to limit them to what has been shown and described above.

[Effects of the Invention] Since the present invention is constructed as described above, it has the following effects.

That is, the first and second claims can each achieve a brightness improvement of about 10%, and the third and fourth claims can also achieve a brightness improvement of about 10%, respectively, and by using these together,
It becomes possible to obtain an Edgelight surface light source device with high luminance that is about 30 to 40% higher than that of the conventional one, and it is also possible to eliminate the disadvantages of light guiding due to the tendency for Edgelight surface light source panels to become thinner.

In addition, in claims 1 and 2, while it is possible to obtain a brightness higher than that obtained by using reflective glass beads which naturally have a large particle size and have poor compatibility with ink, the reflective glass beads This has the effect of eliminating the clogging of screen printing caused by the clogging or preventing this clogging as much as possible, eliminating printing defects that occur at a high rate, and significantly improving the yield.

On the other hand, while claims 3 and 4 each have a remarkable effect on improving brightness, their configurations are extremely simple and can reliably achieve this, and furthermore, each claim causes a significant increase in cost. There is no.

[Brief explanation of drawings]

The drawings show an embodiment: Fig. 1 is a partially cutaway perspective view of a word processor, Fig. 2 is an exploded perspective view showing the main parts of a surface light source device, and Figs. 5 is a longitudinal sectional view showing another example of the surface light source device, and FIG. 6 is a partial front view showing the diffused reflection surface of the edge light surface light source panel in the light source device shown in FIG. 5. It is. 7... Surface light source device 8... Diffusion film 9... Edgelight surface light source panel lO... Transparent resin substrate it... Diffuse reflection surface 14... Ink vehicle 15. 18... Fine hollow Particle part 16... Reflective film 17... Light source 20... Lighting sign

Claims (4)

[Claims] (1) A surface light source device comprising an edge light surface light source panel in which fine hollow particle portions formed by foaming are mixed in an ink vehicle on a diffusely reflecting surface formed by screen printing on one side surface. (2) A surface light source device characterized in that the fine hollow particle portion according to claim 1 is a fine hollow particle portion made of hollow resin powder instead of foaming. (3) A surface light source device characterized in that the reflective surface formed integrally with or arranged in a layered manner on one side surface of an edge-light surface light source panel is a foamed resin surface. (4) A surface light source device characterized in that the light source reflecting surface arranged to cover the non-incident end surface side of the light source facing the incident end surface of the edge light surface light source panel is a foamed resin surface.