Active matrix display devices, and their manufacture
View Patent ↗Physical barriers ( 210 ) are present between neighboring pixels ( 200 ) on a circuit substrate ( 100 ) of an active-matrix display device, such as an electroluminescent display formed with LEDs ( 25 ) of organic semiconductor materials. The invention forms at least parts of the barriers ( 210 ) with metal or other electrically-conductive material ( 240 ) that is insulated ( 40 ) from the LEDs but connected to the circuitry ( 4, 5, 6, 9, 140, 150, 160 , T 1 , T 2 , Tm, Tg, Ch etc.) within the substrate ( 100 ). This conductive barrier material ( 240 ) may back up or replace, for example, matrix addressing lines ( 150 ) and/or form an additional component either within the pixel array or outside. The additional component comprising the conductive barrier material ( 240 ) is advantageously a capacitor (Ch), or an inductor (L) or transformer (W), or even an aerial.
1. An active-matrix display device comprising: a circuit substrate on which an array of pixels is present with physical barriers between at least some of the neighbouring pixels in at least one direction of the array; each pixel comprising a display element; the circuit substrate comprising circuitry to which the display elements are connected; the physical barriers comprising conductive material that is connected with a circuit element in the circuit substrate via contact windows in an intermediate insulating layer on the circuit substrate; and the conductive barrier material being insulated at least at the sides of the barriers adjacent to the display elements.
2. A device according to claim 1 , wherein the said circuit element in the circuit substrate is at least one thin-film element of a group comprising: a conductor layer; an electrode connection; a supply line; an addressing line; a signal line; a thin-film transistor; a thin-film capacitor.
3. A device according to claim 1 , wherein at least insulated lengths of the barrier comprise a metal core that provides the conductive barrier material, which metal core is connected with the circuit element in the circuit substrate and has an insulating coating on at least its sides.
4. A device according to claim 3 , wherein a metal coating is present on the insulating coating on the metal core and is connected to another circuit element.
5. A device according to claim 4 , wherein the metal core, insulating coating and metal coating together form a capacitor, for example an individual holding capacitor for each respective pixel.
6. A device according to claim 1 , wherein at least an insulated length of the barrier comprises a metal coating on an insulating coating on a metal core of at least that length of the barrier, and the metal coating provides the conductive barrier material that is connected with the circuit element in the substrate.
7. A device according to claim 6 , wherein the metal core is of nickel or another ferromagnetic material, and the metal coating is of non-ferromagnetic material that is connected with a conductor track of non-ferromagnetic material in the substrate to form at least one coil of an inductor or transformer that comprises the ferromagnetic metal core.
8. A device according to claim 1 , wherein at least insulated lengths of the barriers are predominantly of the conductive barrier material (and preferably comprising metal).
9. A device according to claim 1 , wherein the physical barrier is predominantly of insulating material through which vias extend for connection with the circuit element in the circuit substrate, and wherein a metal coating that provides the conductive barrier material extends on top of the physical barrier and in the vias through the physical barrier.
10. A device according to claim 1 , wherein the circuit substrate comprises matrix addressing circuitry that is connected with transverse addressing and signal lines, and the conductive barrier material provides at least part of the addressing lines.
11. A device according to claim 1 , wherein the conductive barrier material serves as an interconnection between the said circuit element in the circuit substrate and a further circuit element of the device.
12. A device according to claim 1 , wherein the barriers are present between electroluminescent display elements that comprise a light-emitting diode of organic semiconductor material.
13. A device according to claim 1 , wherein the barriers are spacers in an active-matrix liquid-crystal display.