Backlight units with support posts and cavity height monitoring

Patent metadata

Field	Value
Publication number	US-11294236-B2
Application number	US-202016891386-A
Country	US
Kind code	B2
Filing date	Jun 3, 2020
Priority date	May 3, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

An electronic device may have a display with a backlight. The backlight provides backlight illumination for an array of pixels that is displaying images. The backlight may include an array of cells. Each cell may contain a light source with one or more light-emitting diodes and a cavity reflector that reflects light from the light source outwardly through a diffuser for use in forming the backlight illumination. The light sources may be mounted to a printed circuit. Support posts on the printed circuit may be used to maintain the diffuser at a fixed distance from the printed circuit. Sensors on the printed circuit may be used to measure separation distances between the printed circuit and diffuser. Adjustments to pixel gain profiles can be made based on the measured separation distances.

First claim

What is claimed is:

1. A display, comprising:
an array of pixels configured to display images; and
a backlight configured to produce backlight illumination for the array of pixels, wherein the backlight has a two-dimensional array of cells that each includes a light source and a reflector, a printed circuit on which the light sources are mounted, a diffuser, and support posts that are configured to support the diffuser, wherein the support posts comprise posts formed from protrusions in the diffuser that have an upper portion with a curved flared profile and a lower cylindrical portion.

2. The display defined in claim 1 wherein the support posts include clear polymer portions.

3. The display defined in claim 2 wherein the backlight further comprises screws that each attach a respective one of the support posts to the printed circuit.

4. The display defined in claim 3 further comprising elastomeric gaskets, wherein a respective one of the elastomeric gaskets is interposed between at least part of each screw and the printed circuit.

5. The display defined in claim 4 further comprising a chassis on which the backlight is mounted, wherein the chassis has openings through which a head of each screw passes.

6. The display defined in claim 5 wherein the chassis is a metal chassis.

7. The display defined in claim 5 wherein each screw passes through one of the openings in the chassis, an opening in the printed circuit, and is coupled to a respective one of the support posts.

8. The display defined in claim 1 further comprising:
an array of optical sensors on the printed circuit, wherein the optical sensors measure respective separation distances between the diffuser and the printed circuit.

9. The display defined in claim 8 wherein the support posts are interspersed with the optical sensors on the printed circuit.

10. The display defined in claim 9 further comprising display driver circuitry with a look-up table configured to maintain a pixel gain profile that compensates the images for backlight intensity variations across the array of pixels.

11. The display defined in claim 10 further comprising control circuitry that is configured to update the pixel gain profile in the look-up table in response to measurements of the separation distances from the array of optical sensors.

12. The display defined in claim 8 wherein the optical sensors each include a light-emitting diode and a light detector configured to detect light from the light-emitting diode that has reflected from the diffuser.

13. A display comprising:
an array of pixels configured to display images; and
a backlight configured to produce backlight illumination for the array of pixels, wherein the backlight comprises:
an array of cells, each of which includes a light source and a reflector,
a printed circuit on which the light sources are mounted,
a diffuser overlapping the light sources and reflectors, wherein the diffuser has a planar portion and integral protrusions that extend from the planar portion to the printed circuit to support the diffuser, and
a chassis that supports the printed circuit, wherein the integral protrusions of the diffuser are attached the chassis with screws.

14. The display defined in claim 13 wherein the chassis is a metal chassis.

15. A display comprising:
an array of pixels configured to display images; and
a backlight configured to produce backlight illumination for the pixels, wherein the backlight comprises:
a two-dimensional array of cells that each includes a light source and a reflector,
a printed circuit on which the light sources are mounted, and
a diffuser having a planar portion that overlaps the light sources and integral protrusions that extend from the planar portion, wherein the integral protrusions extend from the diffuser to the printed circuit to support the diffuser, and wherein each integral protrusions has an upper portion with a curved flared profile and a lower cylindrical portion.

Assignees

• Apple Inc

Inventors

• Liu Rong
• Sun Yu P
• Zweigle Erik A
• Qi Jun
• Yin Victor H
• Hong Ziruo
• Bae Sungwon

Classifications

• G02F1/133603

  with LEDs · CPC title

• G02F1/133608 Primary

  including particular frames or supporting means · CPC title

• G02F1/133611

  including means for improving the brightness uniformity · CPC title

• G02F1/133606

  including a specially adapted diffusing, scattering or light controlling members · CPC title

• F21K9/64

  using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer · CPC title