Philips Electronics North America Corporation

Tektronix, Inc.

Henri R Van Helleputte

Babar Ali Khan

Jacob Bruinink

Adrianus Leonardus Burgmans

Petrus Franciscus Bongaerts

Karel E Kuijk

Thomas S Buzak

Kevin J Ilcisin

Paul C Martin

Hans J Den Biggelaar

A flat display device preferably of the PALC type in which the plasma channels are formed by depositing successive layers of electrically conductive and electrically insulating material on a substrate containing spaced walls of a resist material that are preferably structured with a negative slope to form in the space between the resist walls flanking channel walls comprising an electrode layer and rising above it a wall of insulating material with the electrode layer sides exposed to adjacent channels. Subsequently, the resist walls are removed by a lift-off process removing with it the layer deposits on the resist walls leaving behind the layer deposits between the resist walls. The remaining insulating walls are then covered with thin dielectric sheet-like member to form the plasma channels.

Plasmas addressed liquid crystal display with deposited plasma channels

A channel member for a PALC panel has a channel in its surface and a wire in the channel as an electrode of the PALC panel.

PALC panel with wire electrodes

A process for fabricating the channel substrate of a plasma-addressed electro-optic display device comprising a layer of electro-optic material, data electrodes coupled to the electro-optic layer and adapted to receive data voltages for activating portions of the electro-optic layer, and a plurality of plasma channels extending generally transverse to the data electrodes for selectively switching on said electro-optic portions and closed off by a thin dielectric sheet, typically a thin glass sheet. The channel substrate is fabricated using anodic bonding to attach the thin glass sheet to an etched or walled preferably glass substrate containing the channels. This reduces stresses in the thin glass sheet. Reduced stress allows post processing of the thin sheet, particularly further etching to reduce its thickness.

Anodic bonded plasma addressed liquid crystal displays

A flat display device, preferably of the PALC type, in which the plasma channels are formed by etching in a substrate laterally-spaced channels and bonding a thin dielectric sheet over the etched substrate. Adjoining each of the channels are shallow ledges, also formed by etching, which serve as recessed areas to receive enlarged ends serving as contact pads for each of the electrodes. Holes are formed in the thin dielectric sheet and contact material deposited on the bonded thin dielectric sheet such that the deposited material makes electrical contact with the underlying electrode contact pads and seals off the holes, which allows a plasma-forming atmosphere to be provided in the channels. This arrangement results in a glass-to-glass interface between the substrate and the thin dielectric sheet, which allows anodic bonding to be employed to assemble the two elements and thus eliminates the frit glass sealing process required in other constructions.

Method of making a channel plate for a flat display device

A plasma-addressed liquid crystal color display device comprising a layer of liquid crystal material, data electrodes coupled to the liquid crystal layer and adapted to receive data voltages for activating pixels of the liquid crystal layer, and a plurality of ionizable-gas-filled plasma channels extending generally transverse to the data electrodes for selectively switching on said liquid crystal pixels. The plasma channels are sealed off by a thin dielectric sheet, and a color filter layer is provided in the device through which changes in the attenuation of the liquid crystal pixels may be viewed to obtain a color image. To reduce the magnitude of the data voltages needed to activate the device, the device layers are configured and given compositions such that a much higher fraction of the applied data voltages appears across the liquid crystal layer thereby allowing a smaller data voltage to be used to obtain the same effect on the liquid crystal pixels. Another feature of the invention includes location of the color filter between the substrate supporting the column electrodes and the column electrodes. Still a further feature is a color filter made up of dyed porous segments of an anodized aluminum film, or of evaporated pigment segments.

Plasma addressed liquid crystal display with reduced column voltages

A flat display device preferably of the PALC type in which the plasma channels are defined by walls of an organic material, preferably a polyimide material. A protective layer is provided over the polyimide walls to prevent deterioration. Spaced electrode portions are preferably provided on facing surfaces of the walls. The preferred method is to lay down a thick layer of polyimide material and a thin resist over the polyimide layer, pattern the resist, and then use the resist to pattern the polyimide layer in the shape of the desired walls. The walls are then covered with a thin dielectric sheet-like member to form the plasma channels.

Plasma addressed liquid crystal display with organic-walled plasma

A flat display device, preferably of the PALC type, in which the plasma channels are formed by etching laterally-spaced slots in a spacer plate, attaching a thin dielectric sheet over the etched spacer plate, and bonding the etched spacer plate to a transparent substrate such that each channel is formed by the portion of the substrate between flanking walls formed by the etched slots in the spacer plate, adjacent flanking walls in the spacer plate, and the overlying portion of the thin dielectric sheet. By positioning the flanking walls between channel electrode pairs, thus providing glass-to-glass interfaces, anodic bonding can be employed to assemble the three channel elements. Etching can be simplified by pre-attaching the unetched channel plate to the substrate or thin dielectric cover sheet with an intervening etch stop, and etching in situ using the etch stop to prevent etching of the substrate or thin dielectric cover sheet. In a modification, the thin dielectric cover sheet as a separate element is substituted by depositing a continuous layer or multi-layers including an etch stop on the unetched spacer plate so that, following the etching, the deposited layer or multi-layer remains as the thin channel cover.

Plasma addressed liquid crystal display with etched glass spacers

A plasma-addressed electro-optic display device having a layer of electro-optic material, data electrodes coupled to the electro-optic layer and adapted to receive data voltages for activating portions of the electro-optic layer, and a plurality of plasma channels extending generally transverse to the data electrodes for selectively switching on the electro-optic portions. The plasma channels each contain spaced elongated cathode and anode plasma electrodes and an ionizable gas filling. The cathode and anode electrodes are arranged in groups to reduce the connections required. Reference voltages are applied to the grouped cathode and anode electrodes such that the data voltages required to operate the panel are reduced decreasing vertical crosstalk. Various driving voltage waveforms can be used for further crosstalk reduction, to reduce the number of voltage levels required, and cause the cathode and anode electrodes to exchange roles during operation to extend lifetime.

Voltage driving waveforms for plasma addressed liquid crystal displays

Plasma addressed liquid crystal display assembled from bonded elements

A plasma-addressed electro-optic display device having a layer of electro-optic material, data electrodes coupled to the electro-optic layer and adapted to receive data voltages for activating portions of the electro-optic layer, and a plurality of plasma channels extending generally transverse to the data electrodes for selectively switching on the electro-optic portions. The plasma channels each contain spaced elongated cathode and anode plasma electrodes and an ionizable gas filling. To improve performance, reliability and lifetime of the device, at least the cathode electrodes have surface portions of a negative electron affinity material. Preferably, the negative electron affinity material is a film of conductive or semiconductive diamond, diamond-like carbon, or aluminum nitride.

Cathode for plasma addressed liquid crystal display

A flat display device preferably of the PALC type in which a fragile micro-sheet covering the plasma channels is replaced by a more robust plate having etched spaced elongated cavities configured in such a way that the top portions of the plate between side walls of each cavity defining a channel and facing the bottom plate are substantially flat. Preferably, the thickness of the glass top plate separating each plasma discharge from an electro-optic pixel is made substantially uniformly thin while the side walls reinforce and greatly increase the strength of the plate making it less prone to breakage during assembly of a display panel. Preferably, the glass plate is etched by means of a plasma etching process.

Plasma addressed liquid crystal display with etched plasma channels

A method for making an electrical device such as a PALC display device, and the electrical device or PALC device so made, in which a channel plate is provided with substantially vertical side walls, and the electrodes are formed by a self-aligning anisotropic plasma etching process which requires no photolithography. A similar process may be used to form a fanout region for individual contacting of channel electrodes. For improved contacting, preferably the fanout region is also channelled and an upstanding structure such as columns provided in the fanout channels so that the spaces between the columns and between the columns and the side walls are filled up with deposited metal that remains following the anisotropic etching process.

Growing community of inventors

Eindhoven, Netherlands

Henri R Van Helleputte