Active matrix display with dual driving modes

• US 10,037,735 B2
• Filed: 11/14/2013
• Issued: 07/31/2018
• Est. Priority Date: 11/16/2012
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Amundson, Karl R.
• Primary Examiner(s): AWAD, AMR A
• Assistant Examiner(s): Midkiff, Aaron
• Application Number:
  US14/080,209
• Publication Number:
  US 20140139501A1
• Time in Patent Office: 1,720 Days
• Field of Search: 345107, 345211-213, 359296
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167
• CPC Class Codes: G09G 3/3446 with more than two electrodes controlling the modulating element

Abstract

An active matrix electro-optic display (100) includes capacitor electrodes (110, 112) associated with the pixel electrodes (106, 108) so that the pixel electrode and its associated capacitor electrode form a capacitor. The display (100) also includes switching means (120) having one position in which each capacitor electrode (110, 112) is electrically connected to the light-transmissive front electrode (102) of the display (100) and a second position in which each capacitor electrode (110, 112) is electrically connected to a voltage source having a voltage independent of the voltage on the light-transmissive electrode.

Claims

1. An electro-optic display comprising:

a layer of electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field;

at least one light-transmissive electrode disposed on one side of the layer of electro-optic material;

a plurality of pixel electrodes disposed on the opposed side of the layer of electro-optic material from the at least one light-transmissive electrode;

a plurality of capacitor electrodes, each capacitor electrode being associated with one of the plurality of pixel electrodes such that the pixel electrode overlaps with a portion of its associated capacitor electrode to form a capacitor; and

switching means having a first position in which each capacitor electrode is electrically connected to the light-transmissive electrode for reducing voltage transients across the layer of electrophoretic material and a second position in which each capacitor electrode is electrically connected to a first voltage source having a voltage independent of the voltage on the light-transmissive electrode; and

a second voltage source for applying an alternating voltage to the light-transmissive electrode while the switching means is in its second position.

2. An electro-optic display according to claim 1 wherein each pixel electrode is connected to the drain of a transistor that is also connected to a source line and a gate line.

3. An electro-optic display according to claim 1 further comprising a layer of dielectric material and wherein each pixel electrode is in two portions lying on opposed sides of the layer dielectric material, a first portion lying adjacent the layer of electro-optic material, and a second portion connected to the drain or source of an associated transistor, and connected to the first portion by means of a conductive via passing through the layer of dielectric material.

4. An electro-optic display according to claim 1 wherein the electro-optic material comprises a rotating bichromal member, electrochromic or electro-wetting material.

5. An electro-optic display according to claim 1 wherein the electrically charged particles and the fluid are confined within a plurality of capsules or microcells.

6. An electro-optic display according to claim 1 wherein the electrically charged particles and the fluid are present as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material.

7. An electro-optic display according to claim 1 wherein the fluid is gaseous.

8. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label, variable transmission window or flash drive comprising a display according to claim 1.

9. A method for addressing an electro-optic display comprising:

a layer of electrophoretic material comprising a plurality of electrically charged particles disposed in a fluid and capable of moving through the fluid under the influence of an electric field;

at least one light-transmissive electrode disposed on one side of the layer of electro-optic material;

a plurality of pixel electrodes disposed on the opposed side of the layer of electro-optic material from the at least one light-transmissive electrode;

a plurality of capacitor electrodes, each capacitor electrode being associated with one of the plurality of pixel electrodes such that the pixel electrode overlaps with a portion of its associated capacitor electrode to form a capacitor; and

switching means having a first position in which each capacitor electrode is electrically connected to the light-transmissive electrode for reducing voltage transients across the layer of electrophoretic material and a second position in which each capacitor electrode is electrically connected to ground for inducing large voltage drops across the layer of electrophoretic material to induce optical changes,

the method comprising;

(i) with the switching means in its first position, applying a voltage to the capacitor electrode such that the capacitor electrode and the light-transmissive electrode are at substantially the same potential; and

(ii) with the switching means in its second position, applying ground voltage to the capacitor electrode such that the light-transmissive electrode and the capacitor electrode are not at the same potential,

wherein, in step (ii) of the method, an alternating voltage is applied to the light transmissive electrode.

10. A method according to claim 9 wherein each pixel electrode is connected to the drain of a transistor that is also connected to a source line and a gate line.

11. A method according to claim 10 wherein, in step (i) of the method, the voltage is applied to the pixel electrode through the transistor via the source line.