Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1999-04-08
2001-05-29
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C178S018010, C178S018110
Reexamination Certificate
active
06239791
ABSTRACT:
The invention relates to a device comprising a sensor device with a detection device for determining information of at least a part of a surface of the sensor device, a display device comprising an electro-optical medium between two substrates, and a driver for driving the display device in dependence upon the information obtained via the detection device.
Devices of this type (also referred to as touch panels) are generally known, in which different sensor mechanisms can be used. For determining information, it is possible to activate a part of the surface by scanning and measuring, for example activating via light (by means of, for example, a light pen) and by subsequently measuring induced currents or capacitively measuring electric voltages induced by pressure variation. The displayed information may vary from the co-ordinates of the part of the surface to the luminescence of the relevant part or possibly a menu activated thereby in computer applications.
BACKGROUND OF THE INVENTION
A device of this type mentioned in the opening paragraph is described in U.S. Pat. No. 5,194,862. For the sensor device (realized on a panel) described in this patent, it is indicated how it can be used as an overlay for a liquid crystal display device (LCD).
When this type of device is used, notably in portable applications (mini-notebook computers, personal digital assistance devices, telecommunication), it is desirable that a minimal quantity of energy is used.
A further problem is that reflection occurs on reflective faces of the panel. This is at the expense of contrast and color purity.
It is, inter alia, an object of the present invention to provide a device of the type described in which one or more of the above-mentioned problems are largely prevented.
To this end, a device according to the invention is characterized in that the sensor device comprises at least one substrate, a main face of which extends at an angle a with respect to a main face of a substrate of the display device, in which 0<&agr;<15 degrees.
By placing the substrate of the sensor device at an angle, incident light is reflected through such an angle that it usually does not reach the eye of an observer. The loss of contrast and color purity is thereby largely prevented. This is already achieved at an angle &agr;<5 degrees.
Usually, the substrates of the sensor device are parallel. The substrate remote from the display device is preferably placed at an angle a because the reflections on this surface are most disturbing.
A preferred embodiment of a device according to the invention is preferable characterized in that a substrate of a display device remote from the sensor device is provided with a reflector. The use of the reflector provides the possibility of refraining from a backlight, which has an energy-saving effect.
The reflector may be provided on the inner side or the outer side of the substrate of the display device.
In a further embodiment, the substrate of the display device remote from the optical guide comprises a silicon substrate in which, for example drive switches are realized (active addressing) or which incorporates further drive functions.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 4553820 (1985-11-01), Harada
patent: 4911536 (1990-03-01), Ditzik
patent: 5194862 (1993-03-01), Edwards
patent: 5852487 (1998-12-01), Fujimori et al.
patent: 5867151 (1999-02-01), Nakai
patent: 6028595 (2000-02-01), Shiga
patent: 3233301 (1984-03-01), None
Adler Glenn J.
Leenhouts Frans
Flat Panel Display Co.
Patel Nitin
Shalwala Bipin
Waxler Aaron
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