Dual Sided Electrophoretic Display

• US 20080266244A1
• Filed: 04/30/2007
• Published: 10/30/2008
• Est. Priority Date: 04/30/2007
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Zhuang, Zhiming, Boos, John P., Bai, XiaoPing, Vakil, Bharat N.
• Granted Patent: US 8,902,152 B2
• Time in Patent Office: Days
• US Class Current: 345/107
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2310/0221 with use of split matrices G09G3/3644 and G09G3/3666 take precedence
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 3/04 for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• 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

Abstract

A dual-sided electrophoretic display (700) having a first region (701) and a second region (702) is provided. Each of the first region (701) and the second region (702) includes selectively operable members (703,704) that function as pixels for presenting images on the electrophoretic display (700). Each of the selectively operable members (703,704) is driven by a driver circuit (710) by way of corresponding thin film transistors and capacitors (742,742), which are opaque. As the selectively operable members (704) of the second region (702) are bigger than are the selectively operable members (703) of the first region (701), the aperture ratio of the selectively operable members (704) of the second region (702) is greater than in the first region (701) when viewed from the rear side (730). Thus, a contrast ratio of the second region (602), when viewed from the rear side (730) is sufficiently high that text, icons, and characters presented in the second region (602) are legibly visible on the rear side (730).

Claims

1. A display assembly for use in an electronic device, the display assembly comprising an electrophoretic display and a driver circuit coupled thereto, wherein the electrophoretic display comprises at least a first region and a second region, wherein at least the second region is visible from both a front side and a rear side of the electrophoretic display, further wherein a contrast ratio associated with the second region, as viewed from the rear side, is greater than a contrast ratio associated with the first region, as viewed from the rear side.

2. The display assembly of claim 1, wherein the contrast ratio associated with the second region, as viewed from the rear side, is at least two to one.

3. The display assembly of claim 1, wherein a pixel aperture ratio associated with pixels in the second region is greater than a pixel aperture ratio associated with pixels in the first region.

4. The display assembly of claim 1, wherein both the first region and the second region comprise selectively operable elements, wherein a selectively operable element in the first region is smaller than a selectively operable element in the second region.

5. The display assembly of claim 4, wherein the driver circuit is configured to selectively operate each of the selectively operable elements by a plurality of thin film transistors disposed upon a transparent substrate, wherein the second region comprises less thin film transistors per unit area than the first region.

6. The display assembly of claim 1, wherein the driver circuit is common to both the first region and the second region.

7. An electrophoretic display comprising a high-resolution region and a low-resolution region, each region comprising a plurality of selectively operable members, wherein a member size associated with the high-resolution region is at least two times smaller than a member size associated with the low-resolution region.

8. The electrophoretic display of claim 7, wherein the low-resolution region comprises less selectively operable members per unit area than the high-resolution region.

9. The electrophoretic display of claim 8, wherein an aperture ratio associated with the selectively operable members of the low-resolution region is at least 80%.

10. The electrophoretic display of claim 7, wherein at least one operable member of the low-resolution region is configured as a character symbol.

11. The electrophoretic display of claim 7, wherein at least one operable member of the low-resolution region is configured as at least a portion of an icon element.

12. The electrophoretic display of claim 11, wherein the icon element comprises one of a battery indicator and a signal strength indicator.

13. The electrophoretic display of claim 7, wherein the low resolution region is visible from both a front side of the electrophoretic display and a second side of the electrophoretic display, with the low resolution region having a contrast ratio on the second side of at least two to one.

14. The electrophoretic display of claim 7, further comprising a plurality of thin film transistors disposed on a thin film transistor substrate, wherein each of the plurality of selectively operable members is driven by at least one corresponding thin film transistor, the thin film transistor substrate further comprising a plurality of capacitors, wherein each of the plurality of selectively operable members is coupled to at least one corresponding capacitor, wherein the at least one corresponding capacitor is disposed proximately with the each of the plurality of selectively operable members.

15. The electrophoretic display of claim 14, wherein a ratio of a visible surface area of each of the plurality of selectively operable members to a surface area of both the at least one corresponding thin film transistor and the at least one corresponding capacitor is at least two times greater in the low resolution region than in the high resolution region.

16. A portable electronic device comprising multi-windowed housing and a dual-sided electrophoretic display, wherein the dual-sided electrophoretic display comprises a first region visible through a first window and a second region visible through at least the first window and a second window, wherein members of each region are selectively operable by a driver circuit.

17. The portable electronic device of claim 16, wherein a contrast ratio, as viewed through the second window, is at least two to one.

18. The portable electronic device if claim 16, wherein the second region is configured to selectively present fewer visible elements per unit area than is the first region.

19. The portable electronic device of claim 16, further comprising a shield disposed atop at least a portion of the second region such that at least some of the second region is not visible through the first window.

20. The portable electronic device of claim 16, wherein the pixilated region comprises geometrically uniform members, further wherein the segmented region comprises at least some geometrically non-uniform members.