Illumination – Revolving
Reexamination Certificate
1999-10-27
2003-01-14
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S558000, C362S027000
Reexamination Certificate
active
06505946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spread illumination apparatus for use of illuminating a signboard and various kind of reflection type of signboards, in particular, a liquid crystal display apparatus.
2. Related Arts
A liquid crystal display, since it is thin in dimension, light-weighted and low in electric consumption, has been increased in its demand for use of a display apparatus mainly for computer. The liquid crystal, which is a constitutional member of the liquid crystal display apparatus, does not light by itself, and different from a lighting element such as a cathode ray tube needs an illumination means for observing the picture of the liquid crystal. Due to the recent tendency of demanding a thin-sized illumination means, quite often a thin-plate like spread illumination apparatus, that is, a side light system (light conductive system) of illumination apparatus has been used by putting it behind the liquid crystal display.
Hereinafter, based on
FIG. 5
one outlined structure of the side light system of spread illumination apparatus
41
is explained.
A flat transparent substrate
43
made of a member having a high transparency to the light is configured thin approximately rectangular in section, along one side end face
44
a linear light source lamp
42
is disposed. For reference, in order to make it light-weighted the flat transparent substrate
43
may happen to be formed as a wedge-like.
In order to make the most lights of the light source lamp
42
inside the flat transparent substrate
43
, around the lamp
42
is covered with a lamp reflector
45
. Further, In order to prevent the light from leaking, side faces (in
FIG. 5
, merely a side face
46
opposite to the side face
44
is shown) other than the one side face
44
of the flat transparent substrate
43
are added with a reflection member
47
consisting of a reflection tape etc.
The rear side
48
(lower in
FIG. 5
) of the flat transparent substrate
43
is formed with a light diffusion pattern
49
as a spread illumination apparatus for illuminating even a picture regardless the distance from the light source lamp
42
, further lower, a reflection film
50
to reflect the light toward a surface
51
(upper in
FIG. 5
) is disposed.
And, on the surface
51
of the flat transparent substrate
43
a light diffusion film
52
is disposed. The light diffusion film
52
is disposed for avoiding a dot image which is generated by emitting the light from the surface of the display, which are progressing through the flat transparent substrate
43
and most of which reflected by the light diffusion pattern
49
.
The light diffusion pattern
49
, the pattern of which is shown in
FIG. 6
, is formed in such a manner as the diameter of the dot becomes larger according to approaching to the side end face
46
from the opposite side end face
44
where the light source lamp
42
is disposed, by applying a medium containing the light diffusing material directly to the flat transparent substrate
43
.
Thus, the light diffusion pattern
49
, by forming it while varying the rate under which a medium containing the light diffusion and reflection material occupies per unit area according to its location (hereinafter, the rate where a given material occupies per unit area is called as “area density”), and by changing the light volume emitted from the surface
51
after being reflected by the light diffusion pattern
49
, is adapted to emit the light for the face as a whole (the surface
51
) with an even brightness. Here, the light diffusion pattern
49
is shown in
FIG. 6
as being hatched for easy looking although it is not in section.
The above light diffusion pattern
49
is formed by being applied with a medium containing a light diffusion and reflection material and it may be what has a function to increase the light volume to be reflected, and for example as disclosed in Japanese patent laid-open No. Hei 9-33923 there is what makes the light diffuse and reflect due to a concave-convex surface to be formed directly on the rear surface
48
of the flat transparent substrate
43
.
Next, a structure of an illumination apparatus to be used as an auxiliary illumination apparatus in particular for a reflection type of liquid crystal display is explained by outlining it.
Here, mentioning a reflection type of liquid crystal display apparatus, it has a constitution where as an illumination light for illuminating a picture a surrounding light can be used, therefore it does not include inside any illumination apparatus. Accordingly, although, in case the surrounding around the reflection type of liquid crystal display apparatus is bright, an observation of the picture may be possible, if it is comparatively dark, there can be a problem where the observation of the picture is difficult due to the insufficient brightness of the surrounding, therefore in order to observe the picture even if the brightness is not sufficient, it is needed to prepare an auxiliary illuminating means.
As this auxiliary illuminating means, as shown in
FIG. 7
, there is a spread illumination apparatus
1
′. In that constitution, a bar-like (linear) light source lamp
2
is disposed nearby one side end face
4
of a plain flat transparent substrate
3
made of a material high in light permeability and formed rectangular in section.
The flat transparent substrate
3
may be formed wedge-like in configuration for making it light-weighted.
Here, in
FIG. 7
, one surface abutting to a reflection type of liquid crystal display element L is referred to as a lower surface
5
and a face opposite to that, that is, an observation face (picture) side is referred to as an upper face (front face)
6
.
On the upper face
6
of the flat transparent substrate
3
, a light reflection pattern
7
is formed. The light reflection pattern
7
is formed with a plurality of approximately triangular grooves
8
and plain portions
9
adjacent to these grooves
8
. The light reflection pattern
7
is formed in such a manner as the interval between the grooves
8
is differentiated depending on the locations of these grooves. That is, the ratio of the width (occupied area) of the groove
8
to the width (occupied area) of the plain portion
9
is adapted to become gradually larger in proportion to the departing of the flat transparent substrate
3
from the one side end face
4
. In
FIG. 7
, the reflection member to increase the eight volume is omitted in depicting.
When disposing such a spread illumination apparatus
1
′ so as to cover the front surface of the reflection type of liquid crystal display element L, the emitted flight from the lamp
2
enters the flat transparent substrate
3
from the one side end face
4
and progresses toward the opposite face
10
while repeating reflection and refraction within it. In the meantime, the light emitted from the lower surface
5
of the flat transparent substrate
3
illuminates the reflection type of liquid crystal display element L. At that time, since the light volume emitted from the lower surface
5
due to the light reflection pattern
7
is approximately even regardless of the distance from the light source lamp
2
, the reflection type of liquid crystal display element L can be illuminated in a spread manner.
By the way, in the spread illumination apparatus
41
,
1
′ explained as an illumination means for liquid crystal display apparatus (including a reflection type of liquid crystal display element L), each has as a light source lamp
42
,
2
a fluorescent tube such as a cold cathode fluorescent tube (CCFL) or a heat cathode fluorescent tube (HCFL) is used. Since, in response to a recent needs for miniaturization in thickness, the diameter of the above fluorescent lamp is formed to become in particular small, there is an anxiety of being broken due to a small shock.
Further, in order to light the fluorescent tube, it is needed to use generally a high voltage of more than hundreds—1000 V, and provided with a complicated lighting circuit called
Okada Masafumi
Suzuki Shingo
Toyoda Koichi
Minebea Co. Ltd.
O'Shea Sandra
Oliff & Berridg,e PLC
Ton Anabel
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