Transmissive display device

• US 8,804,247 B2
• Filed: 12/08/2010
• Issued: 08/12/2014
• Est. Priority Date: 12/14/2009
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Sugiyama, Keiji, Kasazumi, Kenichi, Yamamoto, Kakuya, Kurozuka, Akira, Itoh, Tatsuo, Shikii, Shinichi
• Primary Examiner(s): CHOI, WILLIAM C
• Application Number:
  US13/515,408
• Publication Number:
  US 20120250306A1
• Time in Patent Office: 1,343 Days
• Field of Search: 359/13, 359/629, 359/630, 359/633
• US Class Current: 359/630
• CPC Class Codes: B60K 2360/334 Projection means
• CPC Class Codes: B60K 2360/339 Translucent dashboard skins
• CPC Class Codes: B60K 2370/334 Projection means
• CPC Class Codes: B60K 2370/339 Translucent dashboard skins
• CPC Class Codes: B60K 2370/81 Fastening of instruments, e.g. to dashboard
• CPC Class Codes: B60K 35/00 Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
• CPC Class Codes: B60K 35/50 Instruments characterised by their means of attachment to or integration in the vehicle B60K35/231 takes precedence
• CPC Class Codes: B60K 37/20 Dashboard panels
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0103 comprising holographic elements
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

A transmissive display device includes: a light source which outputs light; a display part which receives the light from the light source and generates display light representing an image; a deflecting element which changes a direction of the display light emitted from the display part; and a transmissive reflector which reflects, towards a user, light of a wavelength included in the display light emitted from the display part, and transmits light of other wavelengths. An angle formed by a straight line, which extends between an upper edge of an incident area of the display light on the transmissive reflector and a lower portion of an eyebox which is defined as a visible range of the reflected light from the transmissive reflector, with respect to a horizontal line is smaller than a difference between an emission angle and an incident angle of the display light at the transmissive reflector.

Claims

1. A transmissive display device, comprising:

a light source configured to emit light;

a display part which receives the light from the light source to generate display light that represents an image;

a deflecting element which changes a direction of the display light emitted from the display part; and

a transmissive reflector configured to reflect light, which has a wavelength included in the display light emitted from the display part, towards a user and transmits light, which has other wavelengths, wherein

the transmissive reflector includes;

a diffracting element configured to deflect a direction of the display light;

a front transparent member configured to hold the diffracting element at an incident side of the display light which is incident on the transmissive reflector; and

a rear transparent member opposite to the front transparent member, the rear transparent member sandwiching the diffracting element together with the front transparent member,

the front transparent member includes an air contact surface which contacts air,

the diffracting element is inclined with respect to the air contact surface so that a difference between an incident angle of the incident display light on the diffracting element and an emission angle of the display light emitted from the diffracting element becomes small, and

the diffracting element includes at least one inclined area, which is inclined with respect to the air contact surface, and one of a non-inclined area, which is not inclined with respect to the air contact surface, and a free-form surface, which has at least one curvature.

2. The transmissive display device according to claim 1, wherein

with regard to a relationship among a first incident angle of the display light, which is incident on the deflecting element, a first emission angle of the display light, which is emitted from the deflecting element, a second incident angle of the display light, which is incident on the transmissive reflector, and a second emission angle of the display light, which is emitted from the transmissive reflector,

a first angular difference defined as a difference between the first incident angle and the first emission angle is larger than a second angular difference defined as a difference between the second incident angle and the second emission angle, and

the first incident angle is smaller than the first emission angle.

3. The transmissive display device according to claim 2, wherein

a difference between the first and second angular differences is set to become greater as a wavelength width of the light emitted from the light source increases.

4. The transmissive display device according to claim 3, wherein

the first angular difference is larger than the second angular difference by 5°

or more if the wavelength width of the light emitted from the light source is no less than 2 nm.

5. The transmissive display device according to claim 4, wherein

an optical path length of the display light from the display part to the deflecting element is greater than an optical path length along which the display light travels from the deflecting element to the transmissive reflector.

6. The transmissive display device according to claim 5, wherein

an inclination direction of the deflecting element with respect to a horizontal line becomes different in response to a magnitude relationship between the second incident angle and the second emission angle.

7. The transmissive display device according to claim 6, wherein

if the second incident angle is larger than the second emission angle, the inclination direction of the deflecting element is set to be identical to an inclination direction of the transmissive reflector with respect to the horizontal line.

8. The transmissive display device according to claim 1, wherein

the at least one inclined area includes an area on which the display light is incident to depict an edge portion of the image.

9. The transmissive display device according to claim 1, wherein

a difference between the incident angle of the display light on the transmissive reflector and the emission angle of the display light from the transmissive reflector is no less than 6°

.

10. The transmissive display device according to claim 1, wherein

the incident angle of the display light on the transmissive reflector is between 20°

and 25°

.

11. The transmissive display device according to claim 10, wherein

the transmissive reflector has a magnification function to magnify a display image which is created by the display part, and

a magnification ratio of the magnification function is in a range of 3×

to 4×

if the emission angle of the display light from the transmissive reflector is ranged from 45°

to 65°

.

12. The transmissive display device according to claim 10, wherein

the transmissive reflector is a combiner made from a hologram,

the display part includes a display element, and

a wavelength width of the light source is no more than 1 nm.

13. The transmissive display device according to claim 10, wherein

the difference between the incident angle of the display light on the transmissive reflector and the emission angle of the display light from the transmissive reflector is no more than 8°

.

14. The transmissive display device according to claim 13, wherein

the light source includes laser sources which emit laser lights that have wavelengths corresponding to red, blue and green, respectively, and

wavelength widths of the laser lights emitted from the laser sources are no more than 1 nm, respectively.

15. The transmissive display device according to claim 14, wherein

the emission angle of the display light from the transmissive reflector is no more than 50°

; and

the magnification ratio is set to a range of 2×

to 3.5×

.

16. The transmissive display device according to claim 10, wherein

the deflecting element is made from a concave mirror which has a magnification ratio.

17. The transmissive display device according to claim 16, wherein

the magnification ratio of the deflecting element is set to be smaller than the magnification ratio of the transmissive reflector.

18. The transmissive display device according to claim 16, wherein

the incident angle of the display light on the deflecting element is set so that a direction of astigmatism which the deflecting element causes is different from a direction of astigmatism which the transmissive reflector causes.

19. The transmissive display device according to claim 18, wherein

the display light is incident on the deflecting element in an opposite direction to an incident direction of the display light on the transmissive reflector.

20. The transmissive display device according to claim 19, wherein

the incident angle of the display light on the transmissive reflector is set between 15°

and 25°

.

21. The transmissive display device according to claim 20, wherein

the magnification ratio of the transmissive reflector is set to a range of 2×

to 3×

, and

the magnification ratio of the deflecting element is set to a range of 1.2×

to 2×

.

22. The transmissive display device according to claim 16, wherein

a focal distance of the deflecting element is shorter than a distance from the deflecting element to the transmissive reflector.

23. The transmissive display device according to claim 1, further comprising a display unit which stores the display part, wherein

the display unit is provided with an opening from which the display light is emitted, and

a distance between the transmissive reflector and the opening becomes shorter as the emission angle of the display light from the transmissive reflector decreases.