Display With Localized Backlight Dimming

• US 20150296580A1
• Filed: 04/09/2014
• Published: 10/15/2015
• Est. Priority Date: 04/09/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Kim, ByoungSuk, Qi, Jun, Yin, Victor H.
• Granted Patent: US 9,785,007 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133612 Electrical details
• CPC Class Codes: G09G 2320/0686 with two or more screen areas displaying information with different brightness or colours
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

A display may have an array of display pixels for displaying images for a user. A backlight unit may provide backlight for the display pixels. The backlight unit may have a substrate such as a printed circuit substrate. An array of locally dimmable backlight elements may be mounted on the substrate. The substrate may be mounted against an inner surface of a metal electronic device housing or other support structure in an electronic device. Each backlight element may have a semiconductor package containing a semiconductor die. The semiconductor die may have a light-emitting diode and a light-emitting-diode control circuit. The light-emitting-diode control circuit may have a pair of transistors and a capacitor. One of the transistors may be connected in series with the light-emitting diode. The light-emitting diode control circuit may receive control signals on a gate line terminal and a source line terminal.

Claims

1. A display, comprising:

an array of display pixels; and

a backlight that provides backlight illumination for the array of display pixels, wherein the backlight comprises an array of backlight elements and wherein each backlight element includes a light-emitting diode and a light-emitting-diode control circuit that controls how much backlight is emitted by the light-emitting diode.

2. The display defined in claim 1 wherein each backlight element has a plastic semiconductor package.

3. The display defined in claim 2 wherein the light-emitting-diode control circuit of each backlight element is packaged in the plastic semiconductor package for that backlight element.

4. The display defined in claim 3 wherein the light-emitting-diode control circuit of each backlight element includes a transistor.

5. The display defined in claim 3 wherein the light-emitting-diode control circuit of each backlight element includes a first transistor and a second transistor.

6. The display defined in claim 5 wherein the light-emitting-diode control circuit of each backlight element further comprises a capacitor coupled between the first and second transistors.

7. The display defined in claim 6 wherein the light-emitting diode of each backlight element is connected in series with the second transistor of that backlight element and is packaged in the semiconductor package.

8. The display defined in claim 6 wherein the light-emitting diode of each of the backlight elements is packaged in the plastic semiconductor package with the light-emitting-diode control circuit for that backlight element and wherein the plastic semiconductor package for that backlight element also contains the light-emitting diode of another one of the backlight elements.

9. The display defined in claim 6 wherein the plastic semiconductor package for each of the backlight elements contains four of the backlight elements.

10. The display defined in claim 1 further comprising a substrate on which the array of backlight elements is mounted.

11. The display defined in claim 10 further comprising metal structures, wherein the substrate is mounted on the metal structures to dissipate heat from the backlight elements through the metal structures.

12. The display defined in claim 11 wherein the metal structures comprise electronic device housing structures.

13. The display defined in claim 11 wherein the array of display pixels comprises an array of liquid crystal display pixels.

14. The display defined in claim 2 wherein the light-emitting-diode control circuit of each backlight element and the light-emitting diode of each backlight element are part of a common semiconductor die that is packaged in the plastic semiconductor package.

15. The display defined in claim 2 wherein the light-emitting-diode control circuit of each backlight element is formed in a semiconductor die that is mounted in the plastic semiconductor package for that backlight element and wherein the light-emitting diode of that backlight element is a discrete semiconductor device that is separate from the semiconductor die and is mounted in the plastic semiconductor package for that backlight element.

16. An electronic device, comprising:

an electronic device housing;

display layers that display images; and

a backlight with an array of locally dimmed backlight elements that provide backlight illumination for the display layers, each backlight element including a light-emitting diode and a light-emitting-diode control circuit.

17. The electronic device defined in claim 16 wherein the light-emitting diode and the light-emitting-diode control circuit of each backlight element are formed as part of a common semiconductor die.

18. The electronic device defined in claim 17 wherein the backlight is mounted on an interior surface of the electronic device housing and wherein the electronic device housing comprises metal.

19. A display, comprising:

liquid crystal display layers that display images; and

a backlight unit with an array of locally dimmed backlight elements that provide backlight for the liquid crystal display layers, each backlight element including a light-emitting diode and a light-emitting-diode control circuit formed as part of a common semiconductor die in a plastic semiconductor package.

20. The display defined in claim 19 wherein the light-emitting-diode control circuit of each backlight element includes two transistors and a capacitor and receives control signals from a gate line and a source line.