Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Screen other than for cathode-ray tube
Reexamination Certificate
1999-05-14
2001-04-24
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Screen other than for cathode-ray tube
C430S200000, C430S945000
Reexamination Certificate
active
06221543
ABSTRACT:
The present invention pertains to improved color electronic displays, to active substrates for use in electronic displays, and to methods of making active elements that have color filters for use in electronic displays.
BACKGROUND
Difficulties can arise in the fabrication of full color active matrix liquid crystal displays (LCD), especially as demand increases for displays to become larger, brighter, thinner, and lighter, with higher resolution and faster switching times, all at a lower cost.
Active matrix LCDs commonly include a liquid crystal material disposed between an active substrate and a non-active (passive) substrate. The active substrate generally has a regular array, or matrix, of thin film transistors (TFT) arranged in pixels. To add color, color filters can be provided for each of the pixels in an LCD. Currently, color filters in active matrix displays are typically formed onto the flat, non-active display substrates, using either photolithography or direct printing techniques.
SUMMARY
Increasing the size and/or the resolution of electronic displays also increases the number of pixels to control in the display. With more pixels to control, issues regarding electronic switching speed, liquid crystal response times, and color filter alignment can become more important. For example, when assembling color LCDs, improperly aligned or otherwise defective color filters can necessitate discarding the color filter substrate during processing. The associated cost of waste, as well as the probability for error, tends to increase as the number of pixels in the display increases. In addition, there is an ever-growing desire for these displays to have thinner and lighter weight constructions, to use less power while providing enhanced brightness, and to have improved reliability and durability.
The present invention provides improved liquid crystal display constructions that have components selected to enhance overall display performance. Components can be selected to construct improved displays according to the present invention that have, for example, enhanced brightness, lower power consumption, and/or faster switching rates. The present invention also includes improved displays that can be made thinner and lighter while maintaining reliability and durability.
According to the present invention, the following components can be selected to achieve enhanced display performance. Color filters can be provided on the active substrate of an active matrix display, for example, to increase the aperture ratio of the display, resulting in more light through the display. Liquid crystal materials and alignment layers can be selected to increase response times, reduce power consumption, and increase contrast. Spacers can be provided that allow for thinner constructions that are durable. Reflective polarizers can be used that increase lighting efficiency by increasing brightness for the same lighting conditions. These and other components can be selected individually or in combination, for example to synergistically enhance one or more display performance properties.
In accordance with an aspect of the present invention there is provided an improved color active-matrix liquid crystal display. One embodiment provides an electronic display that includes (i) a light source; (ii) a polarizer disposed to transmit and substantially polarize light from the light source, and (iii) a liquid crystal display panel disposed to utilize light transmitted by the polarizer. The display panel includes a bottom substrate, a top substrate spaced a distance apart from the bottom substrate, a liquid crystal layer disposed between the substrates, and a multi-color active layer disposed between the bottom substrate and the liquid crystal layer. The multi-color active layer includes a plurality of independently addressable active elements electrically connected to transparent conductive sub-pixel elements and a plurality of color filters, each aligned with one or more of the transparent conductive sub-pixel elements. The color filters comprise a colorant in a crosslinked composition and are derived from a thermally transferred material. The liquid crystal layer can comprise a fluorinated chiral ferroelectric liquid crystal material.
In another embodiment, the present invention provides a color active-matrix liquid crystal display that has a first transparent substrate having a plurality of independently addressable thin film transistors disposed thereon, each transistor electrically connected to an associated transparent conductive sub-pixel element; a second transparent substrate spaced a distance apart from the first transparent substrate; a liquid crystal layer disposed between the first substrate and the second substrate; and a plurality of color filters disposed between the first substrate and the liquid crystal layer, the color filters comprising a thermally transferred material having a colorant disposed therein, each color filter aligned with one or more of the transparent conductive elements associated with the transistors.
One component that can be selected to improve performance in displays of the present invention is color filters. Accordingly, the present invention provides a new method of making color filters. In one aspect, multiple color filters can be transferred prior to crosslinking to allow inspection and removal (if necessary) of the color filters for reworking of the display substrate.
In one embodiment, the present invention provides a new method of making color filters for liquid crystal display substrates, including the steps of providing a display substrate, thermally mass transferring a plurality of color filters to selected portions of the substrate, each color filter comprising a colorant in a crosslinkable composition, and crosslinking the color filters after the transferring step. After transferring the plurality of color filters to the display substrate and prior to crosslinking, the color filters can optionally be inspected, for example, to determine if defects are present and if alignment is proper. If the filters do not meet inspection criteria, they can be removed by a washing step. After washing, the display substrate can be reworked by transferring another plurality of color filters.
The method of the present invention is particularly suited for thermally transferring a plurality of color filters to an active substrate for color active matrix displays. In this case, an active substrate that has a plurality of independently addressable active devices can be provided as the display substrate for thermally transferring color filters according to the invention.
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Chang Jeffrey C.
Guehler Paul F.
Isberg Thomas A.
Mizuno Kazuhiko
Noda Kazuki
3M Innovatives Properties
McPherson John A.
Pechman Robert J.
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