Illumination – Revolving
Reexamination Certificate
1997-11-13
2001-07-24
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S026000
Reexamination Certificate
active
06264343
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a digitizer tablet with a two-dimensional lighting function and a liquid crystal display device utilizing such tablet.
Digitizer tablets are generally classified by their detection methods into the resistance detection method, the electrostatic capacity method, and the electromagnetic induction method, etc., but structurally, they are generally made of a transparent substrate having one or more transparent electrodes. Normally used for the transparent substrate are glass plates or PET (polyethylene terephthalate), and ITO or tin oxide is used for the transparent electrode. The transparent electrode may be used uniformly over the whole surface, but also in a patterned form. In order to improve the writing feel and to prevent glare effects, the pen Input face is structured to have a plastic film pasted thereon or to provide a fine jog on its surface. Digitizer tablets are used not only as an input device alone but also as a device which can be combined with a CRT or LCD and operate information via a display screen.
Among the prior art, an illuminating device to be arranged in front of a liquid crystal display device is known from Patent Laid-Open Hei 6(1994)-324331. According to the device with the structure proposed therein, illumination can be obtained which is suitable for use with the reflective liquid crystal display mode used widely with various portable equipment.
However, as digitizer tablets with conventional structure have a transparent substrate with one or more transparent electrodes, although there may have been almost no attenuation of the quantity of light inside the transparent substrate, 10% or more of the quantity of light was lost particularly due to surface reflection at the interface between the, transparent electrode and air, thereby becoming dark. Another problem was that as the panel was difficult to look at due to surface reflection, this was especially an issue in the combined use with a display component. Moreover, when pasting an anti-glare film or providing a fine jog on the surface as glare-proof measures, the quantity of light was reduced by another 10% to 20% of the total light transmission, and the contrast effect was reduced due to the irregular reflection on the surface, thereby reducing the picture quality of the display.
The present invention aims at resolving these-problems of the prior art by providing a cost-effective, sample structure of an easy to see, bright digitizer tablet with a two-dimensional illuminating function, and a liquid crystal display device including a digitizer tablet which is especially suitable for use with reflective liquid crystal display modes.
SUMMARY OF THE INVENTION
In order to solve the above problems, the digitizer tablet according to the present invention includes a light source for radiating a bundle of light, and a light-guide element having an light entering face into which the bundle of light enters and which guides the bundle of light entering from the light entering face towards the light-emitting face to illuminate the illuminated body from the light-emitting face.
Preferably, the light-guide element means includes a flat, transparent light-guide body having a light emitting face and an opposite face. The light emitting face is perpendicular to the light entering face. The light emitting face is pasted with a film body having a protrusion thereon. The protrusion includes a bottom protrusion face and a side protrusion face. The bottom protrusion face is substantially parallel to the light emitting face and the side protrusion face is substantially perpendicular to the light emitting face. For example, the protrusion may be formed of a plurality of rib-shaped protruding bodies. In this case, the ratio between the width and the height of each of said protruding bodies is roughly 1:1. The protrusion may also be formed of a plurality of cylindrical protruding bodies. In this case, the ratio between the diameter and the height of each of the protruding bodies is also roughly 1:1.
Preferably, a transparent electrode is provided on the opposite face on the side opposite to the light emitting face of the said light-guide body.
Furthermore, the liquid crystal display device according to the present invention may include a liquid crystal display panel with a display face and a digitizer tablet arranged on the side of said display face of the liquid crystal display panel, wherein the digitizer tablet comprises a light source for radiating a bundle of light, and light-guide means having an light entering face into which the bundle of light enters and which guides the bundle of light entering from the light entering face towards the light-emitting face to illuminate the illuminated body from the light-emitting face.
For example, the liquid crystal display panel may be a reflective display. Preferably, the light-guide element includes a flat, transparent light-guide body with a light emitting face and an opposite face. The light emitting face is perpendicular to the light entering face. The light emitting face is pasted with a film body having a protrusion thereon. The protrusion includes a bottom protrusion face and a side protrusion face. The bottom protrusion face is substantially parallel to the light emitting face and the side protrusion face is substantially perpendicular to the light emitting face. Furthermore, a polarized plate may be arranged in front of the light-guide plate on the opposite to said light emitting face of the light-guide plate.
According to present invention, a cost-effective and simple construction of an easy to see and bright digitizer tablet with a two-dimensional illuminating function can be provided. In particular, a liquid crystal display device can be provided which includes a digitizer tablet suitable for reflective liquid crystal display modes. For the use with a portable computer terminal or the like, it is possible to provide a liquid crystal display without reduction of the picture quality of the display even when putting out the illumination in bright places to save power, and which can effect a high contrast during the lighting.
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patent: 4779166 (1988-10-01), Tanaka
patent: 5153386 (1992-10-01), Siefer et al.
patent: 5274198 (1993-12-01), Landmeier
patent: 5359155 (1994-10-01), Helser
patent: 5396350 (1995-03-01), Beeson
patent: 5584556 (1996-12-01), Yokoyama
patent: 5719649 (1998-02-01), Shono et al.
patent: 5736686 (1998-04-01), Perret, Jr. et al.
patent: 5771039 (1998-06-01), Ditzik
patent: 0545705A1 (1991-06-01), None
patent: A1-0-545-705 (1993-06-01), None
patent: 6-324331 (1994-11-01), None
Funamoto Tatsuaki
Miyashita Satoru
Yokoyama Osamu
Neils Peggy A
O'Shea Sandra
Oliff & Berridg,e PLC
Seiko Epson Corporation
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