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Browse Prior Art Database

METHOD OF INTERCONNECTING STACKED DISPLAYS

IP.com Disclosure Number: IPCOM000009840D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-23
Document File: 3 page(s) / 185K

Publishing Venue

Motorola

Related People

Rob Akins: AUTHOR [+2]

Abstract

A promising path for high brightness or high efficiency full color displays is to stack multiple displays, so that red, blue and green pixels are on top of each other, rather than side-by-side as in a conventional single display. In addition, at least one reflective display, the cholesteric display, can double the brightness of its reflective state if a left handed cholesteric display is stacked on top of a right handed cholesteric display. One of the obvious problems in stacking displays is in interconnecting the rows and columns of each layer to their respective driver electronics. Each layer could be connected to row and column drivers via a TAB or heat seal, as would be done in a conventional single layer display.

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MOTOROLA

Technical Developments

METHOD OF INTERCONNECTING STACKED DISPLAYS

by Rob Akins and George Ventouris

A promising path for high brightness or high efficiency full color displays is to stack multiple displays, so that red, blue and green pixels are on top of each other, rather than side-by-side as in a conventional single display. In addition, at least one reflective display, the cholesteric display, can double the brightness of its reflective state if a left handed cholesteric display is stacked on top of a right handed cholesteric display. One of the obvious problems in stacking displays is in interconnecting the rows and columns of each layer to their respective driver electronics. Each layer could be connected to row and column drivers via a TAB or heat seal, as would be done in a conventional single layer display.

However this would create multiple bonding ledges, increasing the footprint of the display. If row and column drivers must be maintained on separate substrates, due to the size of the display, then this becomes especially cumbersome in displays with more tbau two stacks, and requires that displays be bonded to the drivers prior to stacking. Finally, connecting each layer to independent row and column drivers adds cost, either for multiple heat seals or multiple driver ICs. Thus a need exists for a method to interconnect multiple layers in a stacked display to driver electronics that is low cost and space efficient.

One method is to fabricate the display with one to two bonding ledges so that all row and column interconnects are made on or near those ledges.

Electrical contact to the other layers is accomplished through the use of common intennediate substrates between adjacent layers, with pre-drilled or punched vias in the intennediate substrates. The vias are not plated for front to back electrical contact. Rather, isotropic conductive material is dispensed into the vias to connect the lower substrate on the bottom layer to the upper substrate on the top layer.

Conventional anisotropic conductive material is used to connect from the upper substrate to the lower substrate.

Motorola, Inc. 2000

Specific examples are shown in Figures 1 through 9. Figure 1 is a top view of a stacked display (three layers) with two bonding ledges, one for rows on the bottom glass substrate, and one for columns on the top glass substrate. Figure 2A shows a side view, shown as a slice parallel to the row electrodes. The top and bottom substrates are glass, with two intennediate plastic substrates. The arrows show the conductive path from the row interconnect bonding ledge, up through the isotropic conductive posts deposited in the vias through the plastic substrates, and back down via the anisotropic conductive adhesive, so that all three rows can be driven simultaneously with the same one row driver connection.

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