Display device and head-mounted display

Patent metadata

Field	Value
Publication number	US-11048092-B2
Application number	US-202016988753-A
Country	US
Kind code	B2
Filing date	Aug 10, 2020
Priority date	Mar 30, 2017
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A head-mounted display to be mounted on a head of the user includes a display panel to display an image, a lighting device to supply light to the display device, the lighting device including at least one light source including a blue light emitting element emitting blue light, and a red phosphor to emit red light when excited by the blue light from the blue light emitting element, the red phosphor including a complex fluoride red phosphor and a nitride red phosphor having a content ratio smaller than that of the complex fluoride red phosphor, a lighting controller to control driving of the light source in synchronization with the image display by the display device so that a one-frame display period in the display device includes a turn-on period and a turn-off period, and a lens.

First claim

The invention claimed is:

1. A head-mounted display to be mounted on a head of the user, the head-mounted display comprising:
a display panel to display an image;
a lighting device to supply light to the display device, the lighting device including at least one light source including:
at least a blue light emitting element emitting blue light; and
a red phosphor to emit red light when excited by the blue light from the blue light emitting element, the red phosphor including a complex fluoride red phosphor and a nitride red phosphor having a content ratio smaller than a content ratio of the complex fluoride red phosphor;

a lighting controller to control driving of the at least one light source in synchronization with the image display by the display device so that a one-frame display period in the display device includes a turn-on period and a turn-off period; and
a lens through which an image of the image displayed on the display device is formed in an eye of a user.

2. The head-mounted display according to claim 1 , wherein
the complex fluoride red phosphor includes a fluoride complex red phosphor, and
the fluoride complex red phosphor includes manganese that is an activator.

3. The head-mounted display according to claim 2 , wherein the complex fluoride red phosphor includes a KSF phosphor.

4. The head-mounted display according to claim 1 , wherein
the nitride red phosphor includes an alkaline-earth silicon nitride red phosphor, and
the alkaline-earth silicon nitride red phosphor includes europium that is an activator.

5. The head-mounted display according to claim 4 , wherein the nitride red phosphor includes a CASN phosphor.

6. The head-mounted display according to claim 1 , wherein the red phosphor emits red light of a wavelength in a range from about 600 nm to about 780 nm.

7. The head-mounted display according to claim 1 , wherein the at least one light source includes a green phosphor that emits green light of a wavelength in a range from about 500 nm to about 570 nm.

8. The head-mounted display according to claim 1 , wherein the green phosphor includes β-SiALON.

9. The head-mounted display according to claim 1 , wherein the blue light emitting element includes a semiconductor made of a semiconductor material.

10. The head-mounted display according to claim 9 , wherein the semiconductor includes InGaN.

11. The head-mounted display according to claim 1 , wherein the blue light emitting element emits blue light of a wavelength in a range from about 420 nm to about 500 nm.

12. The head-mounted display according to claim 1 , wherein the lighting controller controls the driving of the at least one light source to start the turn-off period in synchronization with the start of the one-frame display period and to start the turn-off period after the end of the turn-off period and to end the turn-off period in synchronization with the end of the one-frame display period.

13. The head-mounted display according to claim 1 , further comprising a panel controller to control driving of the display panel, wherein
the display panel includes pixels arranged in rows,
the panel controller scans the rows of the pixels in sequence,
the at least one light source includes a plurality of light sources to supply light to the rows of the pixels, respectively, and
the lighting controller controls driving of the plurality of light sources in synchronization with driving of the respective rows of the pixels so that the turn-on period and the turn-off period are present during scanning of the rows of the pixels in sequence.

14. A display device comprising:
a display panel to display an image, the display panel comprising:
a plurality of pixel groups; and
a liquid crystal layer containing liquid crystal molecules shifting from a first alignment state to a second alignment state corresponding to an electric field applied by the plurality of pixel groups;

a lighting device to supply light to the display panel for image display, the lighting device comprising a plurality of light sources corresponding to the plurality of pixel groups;
a panel controller driving the plurality of pixel groups by sequentially scanning the plurality of pixel groups; and
a lighting controller controlling driving of the plurality of light sources in synchronization with driving the plurality of pixel groups, wherein
each light source of the plurality of light sources includes at least a blue light emitting element to emit blue light and a red phosphor to emit red light when excited by the blue light from the blue light emitting element,
the red phosphor contains a fluoride complex red phosphor with manganese used as an activator and an alkaline-earth silicon nitride red phosphor with europium used as an activator,
the fluoride complex red phosphor has a content ratio in a range from 75% to 85% inclusive and the alkaline-earth silicon nitride red phosphor has a content ratio in a range from 15% to 25% inclusive, and
the alkaline-earth silicon nitride red phosphor has a red light afterglow time of approximately 1/100 to 1/1000 of the afterglow time of the fluoride complex red phosphor,
the lighting controller controls each light source of the plurality of light sources to:
maintain the each light source in a turn-off period until a start of a hold period during which the second alignment state of the liquid crystal molecules is held while a pixel group of the plurality of pixel groups corresponding to the each light source is driven by the panel controller; and
make a shift to a turn-on period of the each light source after a predetermined period of time has elapsed since the start of the hold period.

15. The display device according to claim 1 , wherein
the content ratio of the complex fluoride red phosphor is 85%, and
the content ratio of the nitride red phosphor is 15%.

16. The display device according to claim 1 , wherein
the content ratio of the complex fluoride red phosphor is 75%, and
the content ratio of the nitride red phosphor is 25%.

17. A head-mount display comprising:
the display device according to claim 14 ;
a lens through which an image of a displayed image on the display device is formed in an eye of a user; and
a head mounter to be mounted on a head of the user, the head mounter including the display device and the lens.

Assignees

• Sharp Kk
• Nichia Corp

Inventors

• Hayashi Tokumi
• Hatsuda Kenichi
• Akagawa Seitaro
• Morikawa Takeshi

Classifications

• C09K11/675 Primary

  with alkali or alkaline earth metals · CPC title

• C09K11/77348

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title

• H10H20/8512

  Wavelength conversion materials · CPC title

• G02B6/0013

  Means for improving the coupling-in of light from the light source into the light guide (coupling light into light guides in general G02B6/42) · CPC title

• G02B6/0068

  Arrangements of plural sources, e.g. multi-colour light sources · CPC title