Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-02-26
2004-10-05
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C349S069000
Reexamination Certificate
active
06801184
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a backlight device having a pre-combined diffuser and substrate, thereby simplifying the process of assembling the backlight device in a LCD and scanner factory.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional backlight device for a liquid crystal display (LCD) or a scanner includes a tubular lamp
11
, a lighting guide
16
and a diffuser
15
. The tubular lamp
11
emits light, and the light propagates in the lighting guide
16
and propagates out from the diffuser
15
.
The lighting guide
16
includes a transparent substrate
14
and a white reflection sheet
12
. A plurality of protrusions
13
are provided on the substrate
14
to scatter the light propagating in the substrate
14
. The diffuser
15
is used for further scattering the light so that the distribution of the light out from the diffuser
15
is more uniform. If no diffuser is provided, the images of the protrusions
13
can be observed by the user in front of the backlight device.
Referring to
FIG. 2
, the light propagates in the transparent substrate
14
in two paths, indicated by reference numerals
17
and
18
: (1) Light
17
is scattered by the protrusions
13
and then reflected by the reflection sheet
12
back to the substrate
14
. Alternatively, light
17
is directly reflected at the interface between the protrusions
13
and the substrate
14
. In either situation, light
17
is finally reflected back to the substrate
14
. A large part of light
17
has a small angle of incidence, thus goes through the interface
19
and propagates out from the diffuser
15
. A small part of light
17
has a large angle of incidence and is reflected at the interface
19
back to the substrate
14
. (2) Light
18
directly propagates toward the interface
19
. The light
18
has a large angle of incidence and is totally reflected at the interface
19
.
In conclusion, the light reflected at the interface
19
including a small part of light
17
and the whole of light
18
. The light reflected at the interface
19
is scattered by the protrusions
13
, propagates through the substrate
14
and then propagates out from the diffuser
15
.
It is noted that the light
18
does not propagate toward the protrusions
13
at the beginning. However, the light
18
is totally reflected at the interface
19
back to the substrate
14
and then is scattered by the protrusions
13
. It is therefore understood that the light
17
and
18
, which propagate in different paths, is scattered by the protrusions
13
.
The diffuser
15
and the substrate
14
of the conventional backlight device are two separate elements. The LCD or scanner manufacturers need to buy the two elements separately from the suppliers and assemble them in the factories.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a backlight device having a pre-combined diffuser and substrate, thereby simplifying the process of assembling the backlight device in a LCD and scanner factory.
The backlight device of the present invention includes a transparent substrate, a plurality of protrusions, a first layer of transparent material, a second layer of transparent material and a light source. The protrusions are provided on the substrate. The first layer of transparent material is attached to the substrate. Also, the first layer of transparent material has an index of refraction smaller than the substrate. The second layer of transparent material is attached to the first layer of transparent material, while the second layer of transparent material has particles inside. The light source emits light. The light is scattered by the protrusions, propagates through the substrate and the first layer of material, propagates into the second layer of material, is scattered by the particles of the second layer of material, and then propagates out from the backlight device
It is noted that the second layer of material, functioning the same as the conventional diffuser, is combined with the substrate via the first layer of material. Therefore, the process of assembling the backlight device in a LCD and scanner factory is simplified.
Alternatively, the backlight device of the present invention includes a transparent substrate, a plurality of protrusions, a layer of transparent material and a light source. The protrusions are provided on the substrate. The layer of transparent material has an index of refraction smaller than the substrate and has a first surface and a second surface, wherein the first surface is attached to the substrate and the second surface is made rough. The light source emits light. The light is scattered by the plurality of protrusions, propagates through the substrate into the layer of material, is scattered by the second surface, and propagates out from the backlight device.
It is noted that the layer of transparent material is directly attached to the substrate and the second surface of the layer of transparent material functions the same as the conventional diffuser. By such an arrangement, the process of assembling the backlight device in a LCD and scanner factory is simplified.
REFERENCES:
patent: 5153754 (1992-10-01), Whetten
patent: 5237439 (1993-08-01), Misono et al.
patent: 5613751 (1997-03-01), Parker et al.
patent: 5953089 (1999-09-01), Hiji et al.
patent: 6076932 (2000-06-01), Uchida et al.
patent: 6151089 (2000-11-01), Yang et al.
patent: 6242860 (2001-06-01), Sasao et al.
patent: 2273869 (1998-02-01), None
patent: 2336378 (1999-09-01), None
Benq Corporation
Ladas & Parry
Said Mansour M.
Shalwala Bipin
LandOfFree
Backlight device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Backlight device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Backlight device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3293956