Active matrix display device
AssigneeKoninklijke Philips Electronics N.V.
InventorsMartin J. Edwards, John R.A. Ayres
Life of this patent
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Abstract
A display device with capacitive display pixels, in which a drive scheme is used for capacitive coupling of voltages to enable reduced column voltage swings to be obtained. Each pixel has two storage capacitors. The use of two storage capacitors provides some freedom in the choice of the magnitude of the voltage swing provide on one terminal of one of the storage capacitors. The first capacitor (C1) of all pixels of the display may be grounded, and only the second capacitor (C2) is subjected to changes in voltage to be capacitively coupled to the display cell. This provides a flexible capacitor line drive type scheme.
Claims11
A display device comprising an array of capacitive display pixels, each pixel comprising a thin film transistor switching device and a capacitive cell, the cell being connected between the switching device and a cell electrode, wherein each pixel further comprises a first storage capacitor connected between the switching device and a first capacitor electrode and a second storage capacitor connected between the switching device and a second capacitor electrode.
A device as claimed in any preceding claim, wherein the second capacitor electrode is shared between rows of pixels of the display.
A device as claimed in any preceding claim wherein the array is arranged in rows and columns, wherein each row of pixels shares a row conductor, which connects to the gates of the thin film transistors of the pixels in the row, and wherein each column of pixels shares a column conductor to which pixel drive signals are provided.
A device as claimed in any preceding claim, wherein the capacitive cell comprises a liquid crystal cell.
A method of driving a pixel of a display device comprising an array of capacitive display pixels each comprising a capacitive cell and first and second storage capacitors, the method comprising:
- applying a data signal to the cell of the pixel and to one terminal of the first and second storage capacitors, thereby charging the first and second storage capacitors;
- isolating the data signal from the cell;
- and
- applying a step change in the voltage on a second terminal of one of the first and second storage capacitors, while maintaining the voltage on a second terminal of the other of the first and second storage capacitors substantially constant.
Dependencies are inferred from the claim text.