BEAM SCANNING-TYPE DISPLAY DEVICE, METHOD, PROGRAM AND INTEGRATED CIRCUIT

• US 20100060551A1
• Filed: 09/26/2008
• Published: 03/11/2010
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kasazumi, Kenichi, Itoh, Tatsuo, Kurozuka, Akira, Yamamoto, Kakuya, Sugiyama, Keiji
• Granted Patent: US 8,403,490 B2
• Time in Patent Office: Days
• US Class Current: 345/8
• CPC Class Codes: B60R 11/0235 of flat type, e.g. LCD
• CPC Class Codes: B60R 2011/0028 Ceiling, e.g. roof rails
• CPC Class Codes: B60R 2011/008 Adjustable or movable supports
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: H04N 5/7491 of head mounted projectors

Abstract

A beam scanning-type display device used as a head-mounted display (HMD) or a head-up display (HUD) includes a light source (101) which emits a beam, a scanning unit (103) which performs scanning using the beam emitted from the light source (101), a deflecting unit (104) which deflects the beam used for the scanning by the scanning unit (103) in the direction toward an eye of a user, and a wavefront shape changing unit (102) which changes the wavefront shape of the beam from the light source (101) so that the beam spot size falls within the predetermined allowable range, and emits the beam to the wavefront shape changing unit (102).

Claims

1. A beam scanning-type display device comprising:

a light source which emits a beam;

a scanning unit configured to perform scanning using the beam emitted from said light source;

a deflecting unit configured to deflect the beam used for the scanning performed by said scanning unit towards an eye of a user; and

a wavefront shape changing unit configured to change a wavefront shape of the beam emitted from said light source so that a spot size of the beam falls within a predetermined allowable range, and output the beam to said scanning unit.

2. The beam scanning-type display device according to claim 1, comprising

a light detecting unit configured to detect a part of the beam used for the scanning performed by said scanning unit,

wherein said wavefront shape changing unit is configured to change the wavefront shape of the beam based on a result of the detection performed by said light detecting unit.

3. The beam scanning-type display device according to claim 2,

wherein said light detecting unit is configured to detect a reflected light of the beam when the beam enters the eye of the user and is reflected from a cornel of the eye,

said beam scanning-type display device comprises:

a line-of-sight detecting unit configured to detect a line-of-sight direction of the user based on intensity of the reflected light detected by said light detecting unit; and

a visual field position determining unit configured to determine a position of the beam in a visual field of the user, based on the line-of-sight direction detected by said line-of-sight detecting unit, and

said wavefront shape changing unit is configured to change the wavefront shape of the beam, based on the allowable range which varies depending on the position of the beam determined by said visual field position determining unit.

4. The beam scanning-type display device according to claim 3,

wherein an upper limit of the allowable range becomes smaller as the beam becomes closer to a center of a visual field of the user, and becomes greater as the beam becomes distant from the center of the visual field of the user.

5. The beam scanning-type display device according to claim 4,

wherein the upper limit of the allowable range is a greater one of a value according to a visual resolution corresponding to the position in the visual field of the user and a value according to a target display resolution in the center of the visual field.

6. The beam scanning-type display device according to claim 2, comprising:

a spot size determining unit configured to determine a spot size on the retina of the beam entering the eye of the user, based on the result of the detection performed by said light detecting unit, the beam forming a spot having the spot size on the retina, and

a beam curvature control unit configured to gradually adjust a curvature radius of the beam by a predetermined value such that the curvature radius is gradually made closer to a target value within a range which allows the spot size determined by said spot size determining unit to fall within a predetermined threshold value.

7. The beam scanning-type display device according to claim 6,

wherein the target value of the curvature radius of the beam is determined as a maximum value within a range which allows the spot size determined by said spot size determining unit to fall within the predetermined threshold value.

8. The beam scanning-type display device according to claim 7,

wherein said beam curvature control unit is configured to lower the target value in the case where a result of the detection performed by said spot size detecting unit exceeds the threshold value.

9. The beam scanning-type display device according to claim 6,

wherein said beam curvature control unit is configured to change the curvature radius of the beam only when a variation range of the spot size within a predetermined time period is not greater than a predetermined value.

10. The beam scanning-type display device according to claim 6, comprising

a motion detecting unit configured to detect a body motion change of the user,

wherein said beam curvature control unit is configured to retain the curvature radius when the body motion change outputted through the detection is not less than a predetermined value.

11. The beam scanning-type display device according to claim 6,

wherein said beam curvature control unit is configured to cause an increase in the curvature radius of the beam in an increase period and cause a decrease in the curvature radius of the beam in a decrease period, the increase period and the decrease period are repeated alternately.

12. The beam scanning-type display device according to claim 2,

wherein said deflecting unit includes a substrate and a hologram mirror formed on at least a part of said substrate,

said hologram mirror includes a deflection area for guiding the scanning light from said scanning unit toward the eye of the user, and a reflection body for reflecting a part of the beam outputted by said scanning unit toward said light detecting unit.

13. The beam scanning-type display device according to claim 12,

wherein said reflection body is formed in said deflection area, and

said deflection area and said reflection body are multiplexed.

14. The beam scanning-type display device according to claim 12,

wherein said reflection body is formed on at least a part of a peripheral area of said deflection area.

15. The beam scanning-type display device according to claim 12,

wherein said reflection body outputs a strongest reflected light when a spot size on the retina is an optimum value.

16. The beam scanning-type display device according to claim 12,

wherein said light source includes:

a red laser light source;

a blue laser light source; and

a green laser light source obtained by combining an infrared laser light source which emits infrared light having a central wavelength ranging from 750 nm to 1500 nm inclusive and a second-harmonic generation (SHG) element which converts a part of the infrared light to green light, and

said reflection body is configured to reflect the infrared light.

17. The beam scanning-type display device according to claim 16,

wherein said deflecting unit includes a shielding film which shields infrared light on a surface opposite to a surface, of the substrate, to which said hologram mirror is attached.

18. The beam scanning-type display device according to claim 2,

wherein said light detecting unit is configured to separately detect curvature radiuses of beams, in two directions, vertical to an optical axis and orthogonal to each other, the curvature radiuses being included in wavefront shape data of the reflected light.

19. The beam scanning-type display device according to claim 2,

wherein said light detecting unit is configured to detect a reflected light resulting from the beam from said scanning unit and reflected from one of said deflecting unit, a cornel of the eye of the user, the retina of the eye, and an iris of the eye.

20. The beam scanning-type display device according to claim 1,

wherein said wavefront shape changing unit includes a horizontal component changing unit which changes a wavefront shape of horizontal components of the beam, and a vertical component changing unit which changes a wavefront shape of vertical components of the beam.

21. The beam scanning-type display device according to claim 20,

wherein said horizontal component changing unit is configured to change the wavefront shape of the beam more greatly than said vertical component changing unit.

22. The beam scanning-type display device according to claim 20,

wherein said wavefront shape changing unit is provided with said horizontal component changing unit and said vertical component changing unit arranged in series on an optical path, and is configured to sequentially change the wavefront shape of the beam.

23. The beam scanning-type display device according to claim 20,

wherein said wavefront shape changing unit is configured to change the wavefront shape of the beam more greatly in horizontal scanning performed by said scanning unit than in vertical scanning performed by said scanning unit.

24. The beam scanning-type display device according to claim 1,

wherein said beam scanning-type display device is an eyeglass-type image display device comprising:

a pair of lenses each including said deflecting unit;

a pair of temples each extending backwards from an outer periphery of a corresponding one of said lenses, and provided with at least a corresponding one of scanning units; and

folding mirrors each (i) disposed at a position which allows an incidence angle of the beam to the corresponding one of said scanning units to be smaller than an incidence angle of the beam which has been emitted from said light source and directly enters the corresponding one of said scanning units, and (ii) guiding the beam from said light source toward the corresponding one of said scanning units, and

each of said folding mirrors includes;

a first mirror which is disposed at a position apart from said scanning unit in said temple in a vertical direction, and reflects the beam from said light source; and

a second mirror which is disposed at a position closer to said lens than said first mirror, and guides reflected light from said first mirror to said scanning unit.

25. The beam scanning-type display device according to claim 24,

wherein said deflecting unit is a hologram mirror and includes:

an image reflection area for deflecting the scanning light from said scanning unit in the direction toward the eye of the user; and

a folding reflection area which functions as said second mirror.

26. The beam scanning-type display device according to claim 25,

wherein said folding reflection area has an aberration for correcting at least some of aberrations which occur in said deflection area.

27. The beam scanning-type display device according to claim 1,

wherein said wavefront shape changing unit includes:

a lens which receives the beam emitted from said light source;

a mirror which reflects the beam condensed by said lens toward said lens; and

a position control unit configured to control a distance between said lens and said mirror.

28. A beam scanning display method comprising:

emitting a beam;

performing scanning using the beam emitted in said emitting;

deflecting the beam used for the scanning performed in said performing scanning; and

changing a wavefront shape of the beam emitted in said emitting so that a spot size of the beam falls within a predetermined allowable range, and outputting the beam for said performing scanning.

29. A program causing a computer to execute:

emitting a beam;

performing scanning using the beam emitted in the emitting;

deflecting the beam used for the scanning performed in the performing scanning; and

changing a wavefront shape of the beam emitted in the emitting so that a spot size of the beam falls within a predetermined allowable range, and outputting the beam for the performing scanning.

30. An integrated circuit comprising:

a light source which emits a beam;

a scanning unit configured to perform scanning using the beam emitted from said light source;

a deflecting unit configured to deflect the beam used for the scanning performed by said scanning unit towards an eye of a user; and

a wavefront shape changing unit configured to change a wavefront shape of the beam emitted from said light source so that a spot size of the beam falls within a predetermined allowable range, and output the beam to said scanning unit.