US 4,728,175 A · Liquid crystal display having pixels with auxiliary capacitance

Abstract

A light influencing display including at least one pixel having a pixel capacitance and an auxiliary capacitance in parallel with the pixel capacitance is disclosed. The pixel includes electrodes located in at least three spaced apart layers, namely a first electrode including first and second spaced apart electrode portions in a first layer, and a second electrode spaced from and facing the first electrode portions in substantially parallel relations thereto in a second layer. The second electrode is electrically insulated from all external circuit connections and from all other pixel electrodes and liquid crystal display material is disposed between the first electrode and the second electrode. The auxiliary capacitance is provided by at least a first auxiliary electrode in a third layer spaced and insulated from and facing at least the first electrode portion of the first electrode on the side of the first electrode opposite the liquid crystal material. The auxiliary electrode is electrically connected to the second electrode portion of the first electrode. Additional auxiliary capacitance can be provided by including in the pixel a second auxiliary electrode in the third layer connected to the first portion of the first electrode. A method of efficiently constructing such pixels using only one layer of insulation which performs three distinct functions is also disclosed. Further additional auxiliary capacitance may also be provided by including additional auxiliary electrodes located in additional layers.

Claims31

Dependent claims

A light influencing display including at least one pixel having a pixel capacitance and an auxiliary capacitance, said pixel comprising:

a first electrode including at least two spaced apart electrode portions;
a second electrode spaced from and facing said first electrode portions in substantially parallel relation thereto, said second electrode also being electrically insulated from all external circuit connections and from all other pixel electrodes, said first and second electrodes being arranged to allow light influencing display material to be placed therebetween;
and
means, electrically connected to said first electrode for providing said auxiliary capacitance.

1 more element

A method for constructing a pixel in a light influencing display having a plurality of pixels comprising the steps of:

(a) forming above a substrate a first conductor for providing current to said pixel and to at least one other pixel of said display, at least a first auxiliary capacitance electrode for said pixel, and at least one isolation device associated with said pixel;
(b) providing a layer of insulating material which extends over substantial portions of said conductor and substantial portions of said electrode and which substantially protects and isolates said isolation device from unintended contact with other conductors in said display;
and
(c) providing on top of said layer at least a portion of a second conductor for providing current to said pixel and to at least one other pixel of said display arranged so as to cross said first conductor, and a first portion of a pixel electrode disposed at least in part above said first auxiliary electrode for forming a first auxiliary pixel capacitance therewith,
whereby said layer of insulating material performs at least three distinct functions, namely insulating said first and second conductors from one another at the location where they cross, acting as the dielectric material of said auxiliary pixel capacitance, and substantially protecting and isolating said isolation device.

2 more elements

Dependencies are inferred from the claim text.

Liquid crystal display having pixels with auxiliary capacitance

Life of this patent

Liquid crystal display having pixels with auxiliary capacitance

Life of this patent

Abstract

Claims31