Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1993-08-06
2001-07-31
Mengistu, Amare (Department: 2778)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S182000
Reexamination Certificate
active
06268843
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a flat type image display apparatus. This invention particularly relates to a flat type image display apparatus which has a high luminance resolution and a high definition.
2. Description of the Related Art
CRT display devices have heretofore been known as a means for displaying images. The CRT display devices have a high luminance resolution and a high definition, i.e. fine resolution of picture elements, and therefore have heretofore been used widely. However, the CRT display devices have the drawback in that they are large and heavy.
Therefore, recently, flat type image display devices, such as a liquid crystal display device (LCD), a plasma display panel (PDP), and an electrochromic display device (ECD), have been utilized in some fields of application.
However, none of the conventional flat type image display devices simultaneously satisfy the requirements with regard to a high luminance resolution and a high definition. For example, an LCD and an ECD have a comparatively high definition, but have a markedly lower luminance resolution than a CRT display device. By way of example, the luminance resolution of an LCD or an ECD is 16 levels of gradation. Also, a PDP has a lower luminance resolution and a lower definition than a CRT display device.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a flat type image display apparatus which has a high luminance resolution and a high definition.
Another object of the present invention is to provide a flat type image display apparatus which displays an image having very good image quality.
The present invention provides a flat type image display apparatus comprising an active display device, which is divided into picture elements, and a passive display device, which is divided into picture elements and which is superposed upon the active display device.
An LCD or an ECD may be utilized as the passive display device. As described above, such a passive display device has a comparatively high definition and a comparatively low luminance resolution. With the flat type image display apparatus in accordance with the present invention, the active display device is located at the rear of the passive display device. Therefore, the luminance resolution can be increased synergistically. Specifically, when a passive display device having, for example, 16 levels of gradation is combined with an active display device having four levels of gradation, the total number of levels of gradation of the flat type image display apparatus becomes equal to 16×4=64.
It is desirable that an active display device having the same number of picture elements as the passive display device be utilized. However, it is difficult to obtain such an active display device. Therefore, an active display device having a smaller number of picture elements than the passive display device be utilized. In such cases, a plurality of adjacent picture elements of the passive display device are exposed to an equal amount of light emitted by a single picture element (a single light emitting element) of the active display device. However, in the case of an ordinary image, the difference in image density between the adjacent picture elements is very small. Therefore, even when a plurality of adjacent picture elements of the passive display device are exposed to an equal amount of light, the gradation reproducibility does not deteriorate to such an extent that the gradation become imperceptible.
Accordingly, an active display device should preferably be utilized which is suitable primarily for improving the luminance resolution. Specifically, an active display device having more levels of gradation should preferably be utilized. The number of picture elements of the active display device may be smaller than that of the passive display device. By way of example, an electroluminescence panel (EL panel), a PDP, or a light emitting diode panel (LED panel) is suitable as the active display device.
As described above, with the flat type image display apparatus in accordance with the present invention, the passive display device, which is comparatively easy to increase the density of picture elements, is superposed upon the active display device. Therefore, the flat type image display apparatus in accordance with the present invention has a high definition and a high luminance resolution. Accordingly, with the flat type image display apparatus in accordance with the present invention, an image having a very good image quality can be displayed. Also, because the flat type image display apparatus in accordance with the present invention is thin in thickness and light in weight, it is applicable in various fields.
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Fuji Photo Film Co. , Ltd.
Mengistu Amare
Sughrue Mion Zinn Macpeak & Seas, PLLC
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