Liquid crystal display having a rolling backlight

Patent metadata

Field	Value
Publication number	US-11011122-B2
Application number	US-201414917959-A
Country	US
Kind code	B2
Filing date	Sep 10, 2014
Priority date	Sep 10, 2013
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A liquid crystal display (LCD) that may include: a plurality of transistors groups forming a pixel array of said LCD, wherein the transistors groups are independently controllable; a plurality of backlight units, forming a backlight surface of said LCD, wherein the backlight units are independently controllable; a data refresh module configured to periodically refresh data at said groups of transistors, at a specified order, over a refresh cycle time; and a backlight control module configured to periodically dim the backlight units at said specified order over a backlight cycle time which is substantially shorter than the refresh cycle time.

First claim

The invention claimed is:

1. A system for reducing photo-activation of transistors in a liquid crystal display (LCD), the system comprising:
a plurality of groups of transistors arranged in rows and columns which form a pixel array of said LCD;
a plurality of backlight units arranged in rows and columns which form a backlight panel of said LCD, wherein the backlight units are independently controllable;
a data refresh module configured to periodically refresh data at the groups of transistors, wherein the data is being refreshed at a specified data refresh order and at a specified refresh rate over a specified period; and
a backlight control module configured to periodically dim the backlight units at said specified data refresh order and at a specified dimming rate over said specified period, to backlight the one or more of the transistor groups only whenever the data at said transistor groups is not being refreshed,
wherein the LCD is a micro display integrated within a head mounted display (HMD), and operating in a dim-to-refresh ratio in which the specified backlight dimming rate is between 3 times to 10 times higher than the specified refresh rate, and
wherein said operating in the dim-to-refresh ratio eliminates a smearing of an image projected from the micro display over a retina of an eye of a viewer wearing the HMD, whenever a head of the viewer is moving,
wherein the dimming is carried out independently at variable levels so that some of the backlight units are dimmed more or less than others during said specified period.

2. The system according to claim 1 , wherein the backlight control module is further configured to selectively dim backlight units that are located along borders of the LCD.

3. The system according to claim 1 , wherein the data refreshing is carried out in a predefined refreshing pattern which sets out an order of refreshing the pixels and wherein the dimming is carried out in a predefined dimming pattern which sets out an order of dimming the backlight units, and wherein the refreshing pattern and the dimming pattern are synchronized so that the dimming pattern follows the refreshing pattern.

4. The system according to claim 1 , wherein the dimming comprises switching off at least one backlight unit.

5. The system according to claim 1 , wherein at least one of the transistors groups include one or more transistors.

6. The system according to claim 1 , wherein said LCD comprises M transistors groups and N backlight units and wherein N<M.

7. A method of reducing photo-activation of transistors in a liquid crystal display (LCD), the method comprising:
providing a plurality of groups of transistors arranged in rows and columns which form a pixel array of said LCD;
providing a plurality of backlight units arranged in rows and columns which form a backlight panel of said LCD, wherein the backlight units are independently controllable;
periodically refreshing data at the groups of transistors, wherein the data is being refreshed at a specified data refresh order and at a specified refresh rate over a specified period; and
periodically dimming the backlight units at said specified data refresh order and at a specified dimming rate over said specified period, to backlight the one or more of the transistor groups only whenever the data at said transistor groups is not being refreshed,
wherein the LCD is a micro display integrated within a head mounted display (HMD), and operating in a dim-to-refresh ratio in which the specified backlight dimming rate is between 3 times to 10 times higher than the specified refresh rate, and
wherein said operating in the dim-to-refresh ratio eliminates a smearing of an image projected from the micro display over a retina of an eye of a viewer wearing the HMD, whenever a head of the viewer is moving,
wherein the dimming is carried out independently at variable levels so that some of the backlight units are dimmed more or less than others during said specified period.

8. The method according to claim 7 , wherein the backlight control module is further configured to selectively dim backlight units that are located along borders of the LCD.

9. The method according to claim 7 , wherein the data refreshing is carried out in a predefined refreshing pattern which sets out an order of refreshing the pixels and wherein the dimming is carried out in a predefined dimming pattern which sets out an order of dimming the backlight units, and wherein the refreshing pattern and the dimming pattern are synchronized so that the dimming pattern follows the refreshing pattern.

10. The method according to claim 7 , wherein the dimming comprises switching off at least one backlight unit.

11. The method according to claim 7 , wherein at least one of the transistors groups include one or more transistors.

12. The method according to claim 7 , wherein said LCD comprises M transistors groups and N backlight units and wherein N<M.

Assignees

• Elbit Systems Ltd

Inventors

• Ophir Yoav
• Benesh Gil

Classifications

• G09G3/3666

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• G09G2310/024

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• G09G2300/023

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• G09G3/3426 Primary

  the different display panel areas being distributed in two dimensions, e.g. matrix · CPC title

• G09G2320/0646

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