Illumination – Revolving
Reexamination Certificate
2000-01-20
2002-08-13
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S560000, C362S558000, C385S050000
Reexamination Certificate
active
06431716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a spread illuminating apparatus for illuminating a front portion of a display and various kinds of reflection type of displays and so on, in particular for an illuminating means for a liquid crystal display.
2. Conventional Art
A liquid crystal display which functions at a low energy consumption has features such as thin in size and light in weight, so that the demand as an indication apparatus primarily for computer has been increased. However, since the liquid crystal itself does not emit a light, for viewing an image, it needs an illuminating means for observing images, different from a light-emitting element, such as a picture tube.
In particular, in the midst of recent tendency for requiring a thinner type of appliance, as an illuminating means for a liquid crystal display, a spread illuminating apparatus of a thin plate-like type of side light system (light conductive plate system) has been utilized.
Hereinafter, a constitution of a side light system of the spread illuminating apparatus
41
is explained based on FIG.
13
.
Reference numeral
42
shows a bar-like light source lamp such as cold cathode fluorescent lamp (CCFL) or hot cathode fluorescent lamp (HCFL) to be used as a light source for a spread illuminating apparatus. A transparent substrate
43
made of a material having a high transparency is configured of a thin rectangular in section, and along with one side end
44
, a light source lamps
42
is disposed at a given spacing. Now, the transparent substrate
43
may be formed wedge-like, wherein, in order to reduce the weight, in such a manner as the transparent substrate
43
is made the thinner, the farther from the side end
44
at which the light source lamp
42
is located.
Around the light source lamp
42
and at the position where the side end
44
does not face, a lamp reflector
45
formed by vaporizing the silver etc. on a film is disposed. By providing thus the lamp reflector
45
, most light emitted from the light source lamp
42
is enabled to make an incidence into the transparent substrate
43
from the side end
44
. Further, in order to prevent the light from being leaked, to the side ends other than the side end
44
of the transparent substrate
43
(in
FIG. 13
, merely one side end
46
which opposes to the one side end
44
is indicated) reflection members
47
made of reflection tapes and so on are applied.
On a rear surface
48
(low in
FIG. 13
) of the transparent substrate
43
, without depending on the distance from the light source lamp
42
, in order to make the screen of the spread illuminating apparatus emitted evenly, a light diffusion pattern
49
(later being explained in details) is formed, and further downward a reflection plate
50
is disposed in such a manner it covers all of the rear surface
48
. The reflection plate
50
makes the light which tries to emit from the rear surface
48
of the transparent substrate
43
reflected and directed toward the front surface
51
(upper in
FIG. 13
) of the transparent substrate
43
.
Further, a spread illuminating apparatus
41
is provided with a diffusion plate
52
in such a manner as it covers whole of the front surface
51
of the transparent substrate
43
. The reason why this diffusion plate
51
is disposed is explained. That is, since most light which progresses in the transparent substrate
43
and emits from the surface
51
are observed in such a manner as merely the light diffusion pattern
49
brightens (so called a dot-image), in order to remove such dot-image the light diffusion plate
52
makes the light progressing therein overlapped (that is, diffused) and emitted the light approximately evenly on the transparent substrate
43
by making the density and distribution of the emitting light even. The light diffusion pattern
49
shown in
FIG. 14
, as disclosed in the patent laid-open publication No. Hei 5-134251, is formed in such a manner as the diameters of the dots disposed thereon become gradually large in proportion to approaching the side end
46
opposing to the side end
44
, along which the light source lamp
42
is disposed. The light diffusion pattern
49
is formed by coating a medium containing light diffusing and reflecting materials directly on the rear surface
48
of the transparent substrate
43
by a screen printing process.
Thus, the light diffusion pattern
49
is formed by changing the ratio in which, depending on its position per unit area, the medium containing the light diffusing and reflecting materials are defined, (hereinafter referred the ratio by which a given material may occupy per unit to as “area density”), so that the light volume to be emitted from the surface
51
is changed by being reflected by the light diffusion pattern
49
. That is, since the brightness of the light becomes the higher the closer to the light source lamp
42
, in order to realize an even spread emitting, the area density of the light diffusion pattern
49
is formed in such a manner as it becomes the large the far from the light source lamp
42
. Thereby, since the light volume to be reflected on the surface
51
separated as far from the light source lamp
42
, the balance between the distance from the light source lamp
42
and the light volume to be reflected by the light diffusion pattern
49
is to be considered to make the whole body emitted even. Here, although the light diffusion pattern
49
are, in
FIG. 14
, not sectional, hatching is applied for an easy looking.
Although the light diffusion pattern
49
is adapted to be formed by coating the medium containing the light diffusion and reflecting materials on the rear surface
48
of the transparent substrate
43
, it is not limited to such a construction but may be constructed by what is to increase the light reflection, for instance, as disclosed in Japanese Patent Laid-open Publication No. Hei 9-33923, a finely formed concavo-convex surface may be directly formed on the rear surface
48
of the transparent substrate
43
and is adapted to make the light diffused and reflected.
Further, as an illuminating means for a liquid crystal display apparatus, in particular, for what is used as an auxiliary means for a reflection type of a liquid crystal display apparatus, a different type of illuminating apparatus other than the above spread illuminating apparatus
41
is explained as follows. The reflection type of a liquid crystal display is a type which can illuminate the screen making use of environmental light as an illuminating light and there is no need of an internal illuminating means, but when the surrounding is dark, since it becomes difficult to observe the screen, an auxiliary illuminating means will be necessary. As a preferable example, of such auxiliary illuminating means for a liquid crystal display, in the patent application No. Hei 9-347648, a spread illuminating apparatus for being disposed in front of (on both of) a reflection type of a liquid crystal display is disclosed.
What is shown in this type of an illuminating apparatus
1
′ in
FIG. 15
, is what is used while covering an observation surface F of a liquid crystal display element L of the above constitution and its constitution resides, as shown in
FIGS. 15 and 16
, in that a bar-like light source lamp
4
is disposed close to one side end
3
of a plate-like transparent substrate
2
having a high transparency and formed rectangular in section. The light source lamp
4
is formed with a cold cathode fluorescent lamp (CCFL) or a hot cathode fluorescent lamp (HCFL). In addition, as the transparent substrate
2
, so as to reduce the weight, what becomes gradually thinner in thickness as it separates far from the one side end
3
wedgewise, is used.
Here, one side of the transparent substrate
2
(lower in
FIG. 16
) which abuts to a reflection type of the liquid crystal element L in
FIG. 15
is to be called as a lower surface
5
and another side(upper in
FIG. 16
) which is an observation surface (picture surface) opposite to one side is
Minebea Co. Ltd.
O'Shea Sandra
Oliff & Berridg,e PLC
Sawhney Hargobind S.
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