Homochromatic and color display assembly on an electronic device and method for operation thereof

• US 9,064,465 B2
• Filed: 05/07/2008
• Issued: 06/23/2015
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Huang, Jie, Khor, Weng Woh
• Primary Examiner(s): Elahi, Towfiq
• Application Number:
  US12/116,335
• Publication Number:
  US 20080284718A1
• Time in Patent Office: 2,603 Days
• Field of Search: 345 4- 6, 345/102, 345/207
• US Class Current: 1/1
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

The present invention provides an electronic device (100) comprising a homochromatic liquid crystal display (155), a color liquid crystal display (165), and a backlight (175) having a light-pipe (220), the homochromatic liquid crystal display, the color liquid crystal display and the light-pipe being positioned in overlapping relation to each other, the light-pipe arranged to direct light (230d) through both the homochromatic liquid crystal display and the color liquid crystal display, a homochromatic liquid crystal display driver (150) arranged to generate an image on the homochromatic liquid crystal display in response to an image signal, a color liquid crystal display driver (160) arranged to generate an image on the color liquid crystal display in response to an image signal, a processor (103) arranged to receive a light control signal (LS1), and to forward an image signal to one of the homochromatic liquid crystal display driver or the color liquid crystal display driver dependent on the light control signal.

Claims

1. An electronic device comprising:

a homochromatic liquid crystal display;

a color liquid crystal display;

a backlight including a light-pipe;

the homochromatic liquid crystal display, the color liquid crystal display and the light-pipe being positioned in overlapping relation to each other, the light-pipe arranged to direct light through both the homochromatic liquid crystal display and the color liquid crystal display;

a homochromatic liquid crystal display driver, coupled to the homochromatic display, to generate an image on the homochromatic liquid crystal display in response to an image signal;

a color liquid crystal display driver, coupled to the color liquid display, to generate an image on the color liquid crystal display in response to an image signal;

a light sensor arranged to generate a light control signal in response to ambient light incident on the light sensor; and

a processor receiving the light control signal and coupled to the homochromatic liquid crystal display driver and the color liquid crystal display driver, the processor operable to selectively provide an image signal to the homochromatic liquid crystal display driver or to the color liquid crystal display driver dependent on the light control signal, wherein the processor is arranged to forward the image signal to the homochromatic liquid crystal display driver in response to a level of ambient light incident on the light sensor being above a predetermined level and forward the image signal to the color liquid crystal display driver in response to the level of ambient light incident on the light sensor being below the predetermined level.

2. The electronic device as claimed in claim 1, wherein the color liquid crystal display is positioned between the homochromatic liquid crystal display and the light-pipe.

3. The electronic device as claimed in claim 1, wherein the processor is further arranged to forward the image signal between said homochromatic liquid crystal display driver or said color liquid crystal display driver in response to a user actuable control input.

4. The electronic device as claimed in claim 1, wherein the homochromatic liquid crystal display and the color liquid crystal display each comprise twisted-nematic liquid crystal sandwiched between two polarizing filters having perpendicular polarizing directions, the polarizing filters adjacent each other from the color liquid crystal display and the homochromatic liquid crystal display having a same polarizing direction.

5. The electronic device as claimed in claim 1, wherein the processor is further arranged to control the backlight dependent on whether the homochromatic liquid crystal display or the color liquid crystal display is being driven.

6. The electronic device as claimed in claim 1, wherein the homochromatic liquid crystal display driver and the color liquid crystal display driver are implemented by the processor.

9. The electronic device as claimed in claim 1,

wherein the homochromatic liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the color liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the homochromatic liquid crystal display polarizing filter is located in between the homochromatic liquid crystal display twisted-nematic liquid crystals and the color liquid crystal display polarizing filter,

wherein the color liquid crystal display polarizing filter is located in between the color liquid crystal display twisted-nematic liquid crystals and the homochromatic liquid crystal display polarizing filter, and

wherein the homochromatic liquid crystal display polarizing filter has a same polarizing direction as the color liquid crystal display polarizing filter.

10. The electronic device as claimed in claim 1, wherein the homochromatic liquid crystal display comprises twisted-nematic liquid crystals, a first homochromatic liquid crystal display polarizing filter, and a second homochromatic liquid crystal display polarizing filter, the twisted-nematic liquid crystals sandwiched between the first homochromatic liquid crystal display polarizing filter and the second homochromatic liquid crystal display polarizing filter, the second homochromatic liquid crystal display polarizing filter having a polarizing direction perpendicular to a first homochromatic liquid crystal display polarizing filter polarizing direction,

wherein the color liquid crystal display comprises twisted-nematic liquid crystals, a first color liquid crystal display polarizing filter and a second color liquid crystal display polarizing filter, the twisted-nematic liquid crystals sandwiched between the first color liquid crystal display polarizing filter and the second color liquid crystal display polarizing filter, the second color liquid crystal display polarizing filter having a polarizing direction perpendicular to a first color liquid crystal display polarizing filter polarizing direction, and

wherein one of the homochromatic liquid crystal display polarizing filters has a same polarizing direction as an adjacent color liquid crystal display polarizing filter.

11. The electronic device as claimed in claim 10, wherein the adjacent homochromatic liquid crystal display polarizing and color liquid crystal display polarizing filters are in between the homochromatic liquid crystal display twisted-nematic liquid crystals and the color liquid crystal display twisted-nematic liquid crystals.

12. The electronic device as claimed in claim 10,

wherein the first color liquid crystal display polarizing filter comprises an incoming polarizing filter that receives light from the backlight,

wherein the color liquid crystal display twisted-nematic liquid crystals receive light from the incoming polarizing filter,

wherein the second color liquid crystal display polarizing filter comprises an outgoing polarizing filter that receives light from the color liquid crystal display twisted-nematic liquid crystals and outputs the light, and

wherein the color liquid crystal display twisted-nematic liquid crystals twist the light received from the incoming polarizing filter by 90 degrees so that the light has the same polarization direction as the outgoing polarizing filter when the color liquid crystal display twisted-nematic liquid crystals are inactive.

7. A method of operating a display assembly of an electronic device, the method comprising:

measuring a level of ambient light at the device; and

generating an image on the display assembly, the image being a homochromatic image when the level of ambient light is above a predetermined level or a color image when the level of ambient light is below the predetermined level,

wherein the display assembly comprises a homochromatic liquid crystal display for displaying the homochromatic image and a color liquid crystal display for displaying the color image, the homochromatic liquid crystal display and the color liquid crystal display being positioned in overlapping relation to each other,

wherein the display assembly further comprises a processor operable to selectively forward an image signal for generating the image to the homochromatic liquid crystal display in response to the level of ambient light being above the predetermined level and forward the image signal to the color liquid crystal display in response to the level of ambient light being below the predetermined level.

13. The method as claimed in claim 7,

wherein the homochromatic liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the color liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the homochromatic liquid crystal display polarizing filter is located in between the homochromatic liquid crystal display twisted-nematic liquid crystals and the color liquid crystal display polarizing filter,

wherein the color liquid crystal display polarizing filter is located in between the color liquid crystal display twisted-nematic liquid crystals and the homochromatic liquid crystal display polarizing filter, and

wherein the homochromatic liquid crystal display polarizing filter has a same polarizing direction as the color liquid crystal display polarizing filter.

8. A method of operating a display assembly of an electronic device including a homochromatic liquid crystal display, a homochromatic liquid crystal display driver that drives the homochromatic liquid crystal display, a color liquid crystal display, and a color liquid crystal display driver that drives the color liquid crystal display, the homochromatic liquid crystal display and the color liquid crystal display carried in overlapping relation to each other, and a processor, the method comprising:

receiving by the processor a light control signal and an image signal; and

providing an image signal to one of the homochromatic liquid crystal display driver that drives the homochromatic liquid crystal display that overlaps the color liquid crystal display or the color liquid crystal display driver that drives the color liquid crystal display dependent on the light control signal,

wherein the image signal is provided to the homochromatic liquid crystal display driver when a level of ambient light is above a predetermined level of ambient light else provided to the color liquid crystal display when the level of ambient light is below the predetermined level of ambient light.

14. The method as claimed in claim 8,

wherein the homochromatic liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the color liquid crystal display comprises twisted-nematic liquid crystals and a polarizing filter,

wherein the homochromatic liquid crystal display polarizing filter is located in between the homochromatic liquid crystal display twisted-nematic liquid crystals and the color liquid crystal display polarizing filter,

wherein the color liquid crystal display polarizing filter is located in between the color liquid crystal display twisted-nematic liquid crystals and the homochromatic liquid crystal display polarizing filter, and

wherein the homochromatic liquid crystal display polarizing filter has a same polarizing direction as the color liquid crystal display polarizing filter.