VIRTUAL IMAGE DISPLAY APPARATUS

• US 20130222919A1
• Filed: 02/21/2013
• Published: 08/29/2013
• Est. Priority Date: 02/24/2012
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: KOMATSU, Akira, TOTANI, Takahiro, TAKEDA, Takashi, MIYAO, Toshiaki, TAKAGI, Masayuki
• Granted Patent: US 9,977,238 B2
• Time in Patent Office: Days
• US Class Current: 359/630
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/0172 characterised by optical features

Abstract

An intermediate image is formed inside a first prism, and an image light, which is reflected on the order of a third surface, a first surface and a second surface, is transmitted through the first surface and reaches the eyes of the observer, therefore it is possible to make the entire optical system small and light in weight by making the first prism thin, and realize a high performance display device with a wide angle of view. Further, when an external light is passed through, for example, the first surface and the third surface and observed, a diopter scale is set to approximately zero, and thereby reducing the defocus or distortion of the external light when observed in a see-through manner. And, it is possible such that the shape of the first prism conforms to the face of the observer, the center is also close to the face.

Claims

1. A virtual image display apparatus which causes an image light and an external light to be visually recognized simultaneously, comprising:

an image element which generates an image light; and

a prism type image forming optical system including non-axisymmetric curved surfaces of three surfaces or more,

wherein the prism type image forming optical system includes a relay optical system which forms an intermediate image on an optical path,

wherein when the external light is visually recognized by passing the external light through a first surface and a third surface among a plurality of surfaces constituting the prism type image forming optical system, a diopter scale is approximately zero,

wherein the first surface and the third surface form a concave surface shape with respect to an observation side, and

wherein after the image light from the image element is totally reflected on the third surface, then totally reflected on the first surface and then reflected on the second surface, the image light is transmitted through the first surface to reach the observation side.

2. The virtual image display apparatus according to claim 1,

wherein the prism type image forming optical system includes a first prism including non-axisymmetric curved surfaces of two surfaces or more and a second prism including non-axisymmetric curved surfaces of two surfaces or more, and an intermediate image is formed on an optical path from the first prism to the second prism, an optical system including at least the second prism serving as the relay optical system.

3. The virtual image display apparatus according to claim 2,

wherein the first prism and the second prism having a plurality of surfaces are formed separately.

4. The virtual image display apparatus according to claim 2,

wherein the second prism has the plurality of surfaces, and the intermediate image is formed by the image element, the plurality of surfaces of the second prism, and a fourth surface that is a light incident surface of the first prism.

5. The virtual image display apparatus according to claim 1,

wherein the prism type image forming optical system is a single prism including non-axisymmetric curved surfaces of three surfaces or more, and forms the intermediate image inside the prism, as the relay optical system.

6. The virtual image display apparatus according to claim 4,

wherein the prism type image forming optical system has a first prism portion having the first surface, the second surface and the third surface on a light emitting side, and a second prism portion on a light incident side, and the first prism portion and the second prism portion are integrally formed.

7. The virtual image display apparatus according to claim 6,

wherein the second prism portion has the fourth surface, a fifth surface and a sixth surface, and the intermediate image is formed by the image element and the fourth surface, the fifth surface and the sixth surface of the second prism portion.

8. The virtual image display apparatus according to claim 1,

wherein by taking an origin of each of the surfaces constituting the prism type image forming optical system as a standard, when polynomial development of an expressing formula of a surface shape is performed with regard to rectangular coordinates x and y extending from the origin to a tangential direction, by setting Ak_m,n as a coefficient of a term x^m·

yⁿ of the polynomial expression which expresses the k-th surface, conditions of the (1) to (3) below are satisfied;

−

5×

10<sup>−

2</sup><

A1_2,0+A1_0,2<

−

1×

10<sup>−

3</sup> and

−

5×

10<sup>−

2</sup><

A3_2,0+A3_0,2<

−

1×

10<sup>−

3</sup> 

 

(1)

|A3_2,0−

A3_0,2|<

1×

10<sup>−

2</sup> 

 

(2)

|A1_2,0−

A3_2,0|<

5×

10<sup>−

3</sup> and

|A1_0,2−

A3_0,2|<

5×

10<sup>−

3</sup> 

 

(3).

9. The virtual image display apparatus according to claim 1,

wherein an image light is presented to an observer by forming a half mirror in the second surface, and the external light and the image light are superimposed and presented to the observer by integrally disposing a light transmitting member outside of the second surface and making the diopter scale approximately zero with respect to the external light.

10. The virtual image display apparatus according to claim 9,

wherein the light transmitting member has a first transmitting surface and a second transmitting surface on an observer side and a third transmitting surface on an external side, the second surface of the prism type image forming optical system and the second transmitting surface of the light transmitting member have approximately the same curved surface shape, and the second surface and the second transmitting surface are integrated with each other.

11. The virtual image display apparatus according to claim 1,

wherein the first surface, the second surface and the third surface have symmetrical shapes with a reference surface, interposed therebetween, including an optical path passing therethrough.

12. The virtual image display apparatus according to claim 1,

wherein an interval between the first surface and the third surface is 5 mm or more and 15 mm or less.

13. The virtual image display apparatus according to claim 1,

wherein an inclination angle of the second surface with respect to the first surface is 20°

or more and 40°

or less.

14. The virtual image display apparatus according to claim 1,

wherein the image element is integrally fixed with the prism type image forming optical system in order to oppose to the image light incident surface of the prism type image forming optical system.

15. The virtual image display apparatus according to claim 1,

wherein the prism type image forming optical system covers a part of the front of eyes of the observer when worn, with other part of the front of eyes not being covered.

16. The virtual image display apparatus according to claim 1,

wherein the image element includes a signal light forming unit which emits a signal light that is modulated corresponding to the image, and a scanning optical system which scans a signal light that is incident from the signal light forming portion and emits the signal light as a scanning light.