Thin panel display

• US 4,266,223 A
• Filed: 12/08/1978
• Issued: 05/05/1981
• Est. Priority Date: 12/08/1978
• Status: Expired due to Term

• Current Assignee: W H Brady Company
• Original Assignee: W H Brady Company
• Inventors: Frame, Norman J.
• Primary Examiner(s): TRAFTON, DAVID
• Application Number:
  US05/967,578
• Time in Patent Office: 879 Days
• Field of Search: 340/719, 340/781, 313/500, 313/505, 313/498, 315/169.3, 357/45, 358/59, 358/241
• US Class Current: 345/80
• CPC Class Codes: H04N 3/14 by means of electrically scanned solid-state devices for picture generation H04N25/00
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces

Abstract

A multilayer display device with thin-film transistor circuits for sequentially switching a common brightness control signal to a plurality of individual display elements.

Claims

1. A multilayer display apparatus, comprising:

an outer layer;

a plurality of separate radiation-emitting portions beneath said outer layer, each said portion including a control electrode for energizing said portion and said outer layer being transparent to the radiation emitted by said portions;

a plurality of thin-film transistor circuits beneath said portions, each said circuits being adjacent and associated with at least one of said portions and connected thereto via said control electrode;

timing lead means connected to each said transistor circuit for supplying a common timing signal to said circuits;

brightness lead means connected to each said transistor circuit for supplying a common brightness control signal to said circuits;

arming lead means extending between said circuits for supplying arming signals generated by individual said circuits to succeeding said circuits, said arming lead means thereby connecting said plurality of circuits in series;

selection means for making a first group of said circuits sensitive only to a first state of said timing signal and for making a second group sensitive only to a second state of said timing signal, said circuits of said second group being interposed in said series between circuits of said first group, whereby adjacent circuits in said series are not sensitive to the same state of said timing signal;

said transistor circuits including,

switching means for supplying said common brightness control signal from said brightness lead means to said control electrode to said adjacent display portion when the arming signal from a preceding circuit and said common timing signal are sensed,

means for maintaining said switching means in a conductive state, wherein said brightness signal is supplied to said control electrode, for a time sufficient to energize said radiation-emitting portion, and

means for supplying an arming signal to said arming lead means for arming the successive circuit in said series,

whereby successive state changes in said timing signal between said first and second states cause successive said transistor circuits in said series to be activated, thereby energizing successive said radiation-emitting portions in a scanning movement.

2. The display apparatus of claim 1 wherein

said timing lead means includes first and second timing leads for carrying first and second timing signals and

said selection means includes branch leads connecting said first and second timing leads to alternate said transistor circuits in said series.

3. The display apparatus of claim 2 wherein said first timing lead is connected by said branch leads to the first and every other odd numbered circuit in said series,

said second timing lead is connected by said branch leads to the second and every other even numbered circuit in said series, and

said first and second timing signals are pulse trains charging between high and low voltage states and are 180°

out of phase with each other,

whereby adjacent circuits in said series do not simultaneously sense the high state of a timing signal.

4. The display apparatus of claim 1 wherein said means to maintain said switching means of said transistor circuits in a conductive state includes latching means operative during an interval in which said timing signal is sensed and after said arming signal is removed.

5. The display apparatus of claim 4 wherein said latching means comprises to gate supplied with the voltage at said control electrode, whereby said brightness control signal voltage applied at said control electrode provides the voltage required for latching.

6. The display apparatus of claim 1 wherein

said arming lead means comprises an arming lead connected to a gate of the succeeding transistor in said series and

said means for supplying an arming signal comprises a lead connecting said control electrode to said arming lead,

whereby said brightness control voltage applied at said control electrode provides said arming signal.

7. The display apparatus of claim 1 wherein

said transistor circuits each comprise

first, second and third gates, said first gate being connected to said control electrode of said associated radiation-emitting element,

a semiconductor layer beneath said gates,

first and second drains and a source beneath said semiconductor layer, said source being connected to said control electrode and said first gate,

said timing lead means comprises first and second timing leads for supplying first and second timing signals to alternate circuits in said series, said first and second timing signals being pulse trains changing between high and low voltage states and being 180°

out of phase with each other,

said brightness lead means comprises a brightness control lead connected to said first drain,

said arming lead means comprises a plurality of arming leads connected between the control electrode of each said circuit and said second gate of the succeeding circuit,

said selection means comprises branch leads connecting said first timing lead to said third gates of odd numbered circuits in said series and said second timing lead to said third gates of even numbered circuits in said series,

whereby a timing signal state change which supplies a high voltage to said third gate of a said circuit causes conduction between said second drain and said source and the presence of an arming signal at said second gate causes conduction between said first and second drains, thereby connecting said brightness control signal to said control electrode and simultaneously supplying said brightness control signal to said first gate and said arming lead, said arming lead supplying said signal to said second gate of the succeeding circuit in said series to arm that circuit in preparation for the next state change of said timing signal.

8. The display apparatus of claim 1 wherein said control electrodes are third electrodes of said elements and said apparatus further includes two other electrodes being positioned on the side of said luminescent material opposite said third electrode and having transversely intermeshed portions forming an electrode grid, whereby potentials applied to said third electrodes by said brightness control signal switched by said transistor circuits control the brightness of said elements.

9. A multilayer display apparatus, comprising:

a transparent outer layer,

a first and a second electrode beneath said outer layer, each said electrode having portions transversely spaced from portions of the other said electrode,

a layer of electroluminescent material beneath said first and second electrodes,

a third electrode beneath said luminescent layer, said third electrode extending transversely over a display area of said luminescent layer and said display area defining an individual display element of said display apparatus, and

an insulating layer between said luminescent layer and said third electrode, whereby current is substantially prevented from flowing at said third electrode and voltage applied to said third electrode may create a field in said electroluminescent material to move charge carriers normal to said electrode such that the brightness of luminescence visible through said transparent outer layer is varied.

10. The display apparatus of claim 9 further comprising a current - limiting layer between said electroluminescent material and said first and second electrodes, whereby current is substantially prevented from flowing between said first and second electrodes and luminescence is influenced by the electric field generated between said electrodes.

11. The display apparatus of claim 9 wherein

said apparatus further comprises

an insulating layer beneath said luminescent layer and

a plurality of third electrodes in addition to said first mentioned third electrode beneath said insulating layer, each said third electrode extending transversely over a display area of said luminescent layer and said display areas defining a matrix of individual display elements and

said first and second electrode each have a plurality of portions transversely intermeshed with and spaced from corresponding portions of the other said electrode to form an electrode grid extending across an area encompassing a plurality of said display areas,

whereby energization of said grid for said plurality of display areas is accomplished by application of a potential to said first and second electrodes and the luminescence at individual display areas is controlled by the potential applied to said third electrodes.