FR2652667A1 - SURFACE LIGHT SOURCE PANEL. - Google Patents

Abstract

A surface light source panel (12) having an irregular reflective layer (17) disposed on the surface of a transparent substrate (16), said reflective layer having a section (18) with a parallel pattern having an area ratio increasing regularly with distance from a light source (14) along the surface of the panel and a regulating pattern section (19) located near the light source and partially surrounded by said parallel pattern section. Said regulating pattern section has a hump-like outline from the edge near the light source and an area ratio decreasing regularly with the distance from the light source. Such a surface source light source panel can provide a light source with highly uniform distribution brightness and therefore find useful applications including word processors and display devices.

Description

The present invention relates to a light source panel

  surface light for use with a device having a surface light source which finds applications in a variety of lights including

  rear lights using liquid crystals

  rear lights, displays and

display panels.

  I1 has been proposed a device with a surface light source provided with a light source arranged on a

  terminal surface of a superficial light source panel

  which can replace a conventional light source device of the type having a large number of fluorescent light sources arranged on the rear side

  an irregular reflective panel.

  Although such a super light source device

  known form can be achieved in a very thin and compact form, it has the disadvantage of not being able to provide a uniformly distributed brightness. In an attempt to eliminate this drawback, the Japanese patent (Tokkai) N 57-128383 proposes an irregular reflection panel made up of a white paint and having a reflection coefficient which increases regularly with the distance from the surface and the patent Japanese (Tokkai)

  N 60-205576 discloses an irregular reflective layer

  re anterior of a transparent substrate consisting of a white paint to which glass beads are added, while the Japanese patent (Tokkai) N 62-902 discloses a multilayer structure of panels with a surface light source each provided with a layer

reflective irregular.

  Since some of these do not resolve

  not completely the problem, the present applicant has proposed

  registered in Japanese patent application (Tokugan) N 663-

  208670, an irregular reflective layer arranged on

  a surface of a transparent substrate, in which the surface

  this in horizontal section of the reflective layer is regularly increased with the distance from the light source along the layer, and the reflective layer consists of a large number of very small sections.

  reflective irregulars made in the form of nom-

  large dots or bands arranged at a rate of 30 to 65 bands per centimeter by screen printing using a low concentration ink with a solids content of

  13 to 30.t% in order to produce a low power of transmission-

  light. When an irregular reflection layer

  lière according to the above invention is used with a lamp

  8 W fluorescent lamp arranged on its op-

  installed to form a surface light source panel-

  A4 format, it produces such a high brightness

than 2000 nit.

  Although a surface light source panel-

  the one proposed by the present applicant and described above can be used for a device with a surface light source having a variety of practical applications, it has the disadvantage of non-luminous

  uniform which can be seen near the light source

  when used as rear lighting

  of liquid crystal processing machine

  text, computer or portable TV.

  *. The brightness distribution of such a device with a surface light source generally presents

  curved lines that flatten or even become rec-

  tilinear when the irregular reflective layer is

  arranged very close to an edge of the transparent substrate.

  Although such a super light source panel

  surface provides practically a uniform distribution of brightness, a slight lack of uniformity of brightness which it has can be accentuated to deteriorate the overall effect of the panel, in particular when it is used

  in a device where the uniformity of brightness is ri-

exquisitely required.

  One of the aims of the present invention is therefore

  -following to propose a panel with superficial light source

  which is free from the above problem and provides

  highly uniform light distribution for satis-

make severe demands.

  As a result of intensive research efforts by the applicant, it has been found that the curved distribution of luminosity of a panel with a conventional surface light source is caused by the fact that the light coming from the light source and striking the transparent substrate does not does not necessarily become straight, but tends to be tilted in an attempt to become parallel to the diagonals

  so the beams of the incident light are -

  concentrated on the curved area between the oppo- ends

  light source, so that a surface light source panel having a reflective layer

  whose surface in horizontal section is regularly increased

  mented with the distance from the light source cannot effectively compensate for the non-uniform distribution of brightness due to concentrated incident light due to

  that the regular increase in the surface in horizontal section-

  tale always has a parallel pattern and that, when a fluorescent lamp is used, the reduced brightness

  at or around the two opposite bases can accentuate the

  non-uniform partition of brightness.

  It was also found that a panel with

  surface light source provided with a reflective layer

  Irregular lens placed near an edge of the transparent substrate is under the direct influence of the light source which cannot be suppressed by the parallel pattern. Based on these findings, the aforementioned object, as well as others, of the present invention are achieved by providing a panel with a surface light source comprising an irregular reflective layer disposed on the surface of a transparent substrate, in which said reflective layer has a section with a parallel pattern having an area ratio increasing regularly with

  the distance from a light source along the surface

  face of the panel and a regulating pattern section located near the light source and partially surrounded by said parallel pattern section, said regulating pattern section having a bump-like outline extending from the proximity of the edge to the source bright and

  an area ratio steadily increasing with the

  tance from the light source. According to a second aspect of the invention, a light source panel is provided.

  surface with an irregular reflective layer

  creeper arranged near a side edge of a trans-

  parent, wherein said irregular reflective layer

  re has a section with a parallel pattern having an area ratio increasing regularly with the distance from a light source along the surface of the panel and a section with a regulating pattern located close to said lateral edge and having a parallel or shaped outline

  bump, said regulating pattern section having a

reduced surface area.

  With a surface light source panel

  according to the invention, since the reflective layer irre-

  the part of the panel where the incident light has a high concentration of beams or the part which is directly influenced by the incident light has a substantially reduced cross-sectional area, the irregular reflection of the light on the regulating pattern section ensures propagation sufficient light inside the separation surface and simultaneously uniform brightness by cooperation with the parallel pattern section

  to suppress light radiation by irreparable reflection

  on the irregular reflective layer.

  The present invention will now be described.

  in more detail with reference to the accompanying drawings which represent

  feel preferred embodiments of the invention.

  Figure 1 is a perspective view of a ma-

  word processing china. carrying a mode of realization

  sation of the surface light source panel of the

  vention. Figure 2 is an exploded perspective view of the main components of the processing machine

text of Figure 1.

  Figure 3 is an anterior view of an apparatus

  for use in the present invention.

  Figure 4 is a plan view of a mailing sheet used in the embodiment of Figure 3.

  Figures 5 and 6 are plan views of the pan-

  two modes of surface light source

different realization.

  Referring first to Figure 1, the number

  reference fre 1 designates as a whole a word processing machine comprising a main body carrying a keyboard 3 and a raised display section 5 which can be folded over the main body 5 in order to

  facilitate storage and transport.

  Said foldable display section 5 is produced

  read as a thin, wide panel with

  a thickness of about 1 cm or a third of that available

  existing similar visualization devices which is normal-

  approximately 3 cm. The viewing section carries a viewing surface 7 consisting of a liquid crystal panel 9 which is protected by a panel

transparent protector 8.

  On the rear side of the crystal panel 9

  liquids of the foldable viewing section 5 is available

  placed a device 10 with a surface light source.

  Said apparatus 10 with surface light source comprises a transparent irregular reflective sheet 11 made of a translucent polyester film, a panel

  12 with a surface light source and a sheet

  reflective cover 13 also made of a translucent polyester film arranged in a layered structure

  as seen from the front side. The apparatus 10 also includes

  light source 14 which is a fluorescent lamp

  located at the bottom of the device and a reflective section

  terminal health 15 consisting of a white band and surrounded

  the three edges of the panel 12 with light source above

  other than the edge where the source is located

bright 14.

  The light source 14 with a fluorescent lamp in this embodiment is produced in the form of a tube said to have a cylindrical opening having a region with a longitudinal transmission slot disposed opposite the panel.

  12 with superficial light source and the rest of the surface

  face being covered by a non-reflective material

  indoors or outdoors - to maximize the amount

  tity of light striking the panel with light source above

  perfidious. The panel 12 with surface light source is prepared using a transparent resin substrate 16

  transparent acrylic with lateral and long dimensions

  dimensions of 130 x 240 mm and a thickness of 6 mm, the rear surface of which is coated with a reflective layer

  irregular 10 with dense meshes.

  The irregular reflective layer 17 comprises

  a parallel pattern section 18 and a patterned section

  regulator 19, the parallel pattern section 18 of which covers all of the irregular reflective layer 17 except for the part occupied by the pattern section

  regulator 18 and is formed so that its surface-

  cic increases regularly with the distance from the light source in the direction parallel to the lateral surface of the layer 17. In this embodiment, the regular increase in the area ratio is maximized at a location slightly offset towards the upper terminal reflective section 15 from the middle

  of panel 12 with a surface light source between the source

  this luminous 14 and the upper reflecting section 15

  to ensure uniformity in the parallel pattern section

  lele 18, preventing the area near the reflected section

  chissant terminale 15, which is furthest from the

  this bright, becoming too bright as a result of the lu-

  material reflected by the terminal reflecting section 15.

  On the other hand, the regulating pattern section 19 is made so that it has a shaped contour

  bump from the bottom edge of the red layer

  bending irregular 17 facing the light source

  neuse 14 and surrounded by the section with a parallel pattern 18 in order to further reduce the surface area ratio of the part of the section 18 with a parallel pattern which surrounds the section

19 with regulator pattern.

  The reduction in the area ratio of section 19 with a regulating pattern is preferably found between several and 15%. Its surface ratio with respect to the part 18 with surrounding parallel pattern is preferably regularly increased. If so, the increase

  of the area ratio is practically visually indiscer-

  from the outside of the panel 12 with a surface light source. Although an irregular reflective layer 17 comprising a section with a parallel pattern 18 and a section with a regulating pattern can be prepared by screen printing disclosed in Japanese patent application N 63-208670 by the present applicant or by using a white printed film or in using a technique known by percussion, it is preferably prepared, either by screen printing, or

  by applying a film because one or the other ensures a precise

  high sion and the use of a simple process and

reliable as described below.

  When, for example, an irregular reflective layer 17 is formed by screen printing, a section with a parallel pattern 18 and a section with a regulating pattern 19

  can be produced on a second negative film in the former

  posing in ultraviolet light for projection

  an irregular reflection pattern.

  Figure 3 shows a camera for the preparation of a second negative film 31. In Figure 3, the reference numeral 21 designates a light box, 22 a lighting lamp, 23 a translucent glass panel for reflection irregularly arranged on the

  upper side of the light box 21, 24 a frame

  both on its upper surface a glass panel trans-

  parent 25 and 26 a camera.

  Shooting using a second new film

  gatif 31 during the photography is carried out by placing a negative film 27 carrying a mesh pattern and available from Retra Japan and a square diffusion sheet

  28 made of translucent polyester film in many

coarse layers.

  At the time of the shooting, another sheet-

  diffusion 29, made of a polyester film

  lucideret provided with a cut-off zone 30 which corresponds to

  the shape of the regulating pattern section 19 as shown

  felt in Figure 4, is also placed under the film ne-

  gative 27 between the transparent glass panel 25 and the

negative film 27.

  When the parallel pattern on the negative film 27 is reproduced on the second negative film using the

  diffusion sheet 29, the light beams that strike

  in the cut zone 30 directly reach the negative film 27 while the beams which strike the zone

  masked remaining reach negative film after crossing-

  diffusion layer 29 and therefore with a somewhat reduced intensity so that the image of the pattern

  is recorded on the second negative film 31.

  Since the intensity of the light beams

  the cutting zone 30 is greater than that of the

  beams coming from the masked area, the first beams

  these progress as if they were going behind the mail-

  the negative film 27 to reduce the area ratio of each of the meshes when they are recorded so that both said parallel pattern section 18 and said regulator pattern section 19 are received on the

  second negative film simultaneously.

  Since the diffusion layer 28 on the new film

  gatif 27 diffuses the illumination light evenly

  maintaining the uneven light intensity distribution

  original material, the limit line of the cut-off zone 30 of the lower diffusion zone 29 is blurred so that the section with a parallel pattern 18 moves regularly

  in the regulator pattern section 19.

  If, on the other hand, the film cut-off area

  the lower diffusion sheet 29 is replaced by a transparent sheet, an intermediate colored light masking section can be placed between the transparent cutting sheet and the masking section in order to increase the smooth transition of the section with a parallel pattern 18

  to the regulating pattern section 19 and vice versa.

  - The screen printing operation using a PVA film which has been exposed using the second negative film 31 can

  be performed on the transparent substrate 16 according to a pro-

  known ceded using ink disclosed in said

  Japanese patent application N 63-01108670.

  An apparatus with a surface light source 10 constituting the first embodiment of the panel 12 to

  surface light source of the invention can effectively

  cement eliminate any variations in brightness

  due to the concentration of incident light, such as

  vee in a similar classic device and therefore provides uniform and bright rear lighting

  of a liquid crystal panel 9 by incident light

  te from the light source 14. Figure 6 shows an embodiment of the panel 32 with surface light source according to the second

  aspect of the invention. Similarly to the first mode of

  Reading as described above, this embodiment is designed for rear lighting of a liquid crystal display device having a pair of light sources 14 arranged at opposite ends.

of the panel.

  As in the case of the first embodiment,

  an irregular reflective layer 33 is formed by se-

  screen printing on the entire transparent substrate 16 to

  except for the edges close to the light areas respec-

  tives 14. Said irregular reflective layer 33

  carries a parallel pattern section 34 having des- mail-

  les whose surface area ratio gradually increases with the distance from the light sources 14 along the

  panel area, the maximum area ratio is found

  in the middle between the two light sources, and a pair of regulating pattern sections 35 arranged close and substantially parallel to the respective lateral edges

with a reduced surface area ratio.

  The regulating pattern sections 35 are formed using diffusion sheets with reduced width on both side edges when the second negative film is exposed to light while the central area is masked so that the two side edges are subjected to direct light exposure. On the other hand, the panel 32 with surface light source is prepared in a manner identical to that of the first mode of

  realization and so another explanation will be omitted here.

  This embodiment of the panel 32 with a surface light source is also free from any variations in brightness which can normally be encountered when an irregular reflecting layer is arranged.

  near the side edges of the panel and, therefore,

  on uniform and bright rear lighting of

liquid crystal panel.

  Although the embodiments described above

  on be made using one or more sheets

  of diffusion, the irregular reflective layer comprises

  both a section with a parallel pattern and a section with a regulating pattern of a panel with a surface light source

  according to the invention can, as a variant, be carried out using

  reading a pattern designed and modified using a calculator which is then materialized when the negative film is produced. In such a case, it goes without saying that leaves

  lower broadcast is not required.

  Although a surface light source panel-

  the according to the invention is mostly used from

  appropriately for a super light source device

  which must meet the requirements for high precision and uniformity of back lighting of liquid crystals, it can also be used for

  a device with a surface light source for

  viewing replications using positive films

  and rear lighting either for interior decoration

  be for decoration -exterior as

  rear light source or the like.

  With such applications, two or more surface light source panels can be used in a multi-layer structure with irregular reflection / transmission films arranged between them. A surface light source panel according to

  the invention can reliably meet these needs.

  In addition, a panel with a surface light source according to the invention can be used as a prior light source as well as as a light source by

  the back. In addition, a superficial light source panel

  cielle according to the invention can be achieved with an over-

curved face.

  As is apparent from the description above

  of, a panel with a surface light source according to the invention is not limited to the embodiments mentioned

  and he may, jointly with his section with parallel motive-

  the model and its regulating pattern section (s), be modified

  trusted with regard to dimensions, number, shape,

  configuration and application without leaving the portal

nor the spirit of the invention.

  A panel with a surface light source according to the invention is completely free of increased brightness

  unwanted from a super light source device

  near the light source and provides a luminous

  sity with highly uniform distribution so that it can

* meet strict requirements for rear lighting

  for a liquid crystal display device.

R E V E N D ICATIONS

  1. Panel (12) with surface light source

  comprising an irregular reflecting layer (17)

  placed on the surface of a transparent substrate (16), charac-

  characterized in that said reflective layer has a section (18) with a parallel pattern having a surface area increasing regularly with distance from a light source (14) along the surface of the panel and a section (19) with a regulating pattern located near the light source and partially surrounded by said section to

  parallel pattern, said regulating pattern section having

  with a bump-like outline near the edge near the light source and an area ratio decreasing steadily with distance from the

light source.

  2. Panel (32) with a superficial light source

  bearing an irregular reflecting layer (33) disposed near a side edge of a transparent substrate (16),

  characterized in that said irregular reflective layer

  lière has a parallel pattern section (34) having

  an area ratio steadily increasing with the

  tance from a light source (14) along the surface of the panel and a regulating pattern section (35) located near said lateral edge and having a parallel or hump-like outline, said regulating pattern section

  having a reduced surface area ratio.