OPTICAL ENGINE AND WIDE ANGLE PROJECTION LENS MODULE THEREOF

• US 20100079733A1
• Filed: 09/27/2008
• Published: 04/01/2010
• Est. Priority Date: 09/27/2008
• Status: Active Grant

• Current Assignee: Meistream International Optical, Ltd.
• Original Assignee: Meistream International Optical, Ltd.
• Inventors: Lu, Kai-Chang
• Granted Patent: US 7,738,190 B2
• Time in Patent Office: Days
• US Class Current: 353/69
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Abstract

A wide-angle projection lens module is provided, including a reflective convex aspheric mirror and a refractive lens group of positive refractive power. The following Conditions (1) to (2) are satisfied:

15<|F_reflective/F|<25  Condition (1); and

1.5<|F_refractive/F|<2.0  Condition (2),

• • wherein, F is a focal length of the wide-angle projection lens module, F_reflective is a focal length of the reflective convex mirror, and F_refractive is a focal length of the refractive lens group.

Claims

1. A wide-angle projection lens module comprising the following components in sequential order from an output side:

(a) a first lens group with a convex aspheric reflective surface;

(b) a second lens group of negative refractive power having at least one aspheric surface;

(c) a third lens group of substantially zero refractive power, wherein an aperture stop of the wide-angle projection lens module lies within or near the third lens group; and

(d) a fourth lens group of positive refractive power, wherein the folowing conditions (1) to (4) are satisfied;

10<

|F₁/F|<

30 

 

Condition (1);

4.0<

|F₂/F|<

8.0 

 

Condition (2);

25<

|F₃/F|<

50 

 

Condition (3); and

3.5<

|F₄/F|<

6 

 

Condition (4),

where

F is the focal length of the wide-angle projection lens module;

F₁ is the focal length of the first lens group;

F₂ is the focal length of the second lens group;

F₃ is the focal length of the third lens group; and

F₄ is the focal length of the fourth lens group;

2. The wide-angle projection lens module of claim 1, wherein the wide-angle projection lens module is incorporated in a front projection display system.

3. The wide-angle projection lens module of claim 1, wherein the wide-angle projection lens module is incorporated in a rear projection display system.

4. The wide-angle projection lens module of claim 1, wherein the first lens group comprises a rotational symmetrical convex aspheric folding mirror.

5. The wide-angle projection lens module of claim 1, wherein the second lens group comprises a first lens element and a second lens element, a first surface of the first element having a radius of curvature substantially equal to that of a second surface of the second lens element, and the first surface contacts the second surface.

6. The wide-angle projection lens module of claim 1, wherein the following Conditions (5) further satisfies:

|Diameter of the image circle/F|>

4.5 

 

Condition (5),

where,

Diameter of the image circle is equal to 2 times that of a rear image height.

7. The wide-angle projection lens module of claim 1 having a speed of less than or equal to about F/2.8 and an effective focal length of about 4 mm.

8. The wide-angle projection lens module of claim 1, wherein the second lens group comprises two meniscus shaped lens elements nested with each other.

9. The wide-angle projection lens module of claim 1, wherein the third lens group comprises at least two cement lens elements.

10. The wide-angle projection lens module of claim 1, wherein the fourth lens group comprises at least four positive lens elements and at least two negative lens elements.

11. The wide-angle projection lens module of claim 1, wherein the fourth lens group comprises at least four positive lens elements, and an average Abbe value of all the positive lens elements of the fourth lens group is greater than 70.

12. The wide-angle projection lens module of claim 11, wherein the average Abbe value of all the positive lens elements of the fourth lens group is greater than 80.

13. A wide-angle projection lens module comprising the following components in sequential order from an output side:

(a) a first lens group with a convex aspheric reflective surface;

(b) a second lens group of negative refractive power, having at least one aspheric surface;

(c) a third lens group of substantially zero refractive power, wherein an aperture stop of the wide-angle projection lens module lies within or near the third lens group; and

(d) a fourth lens group of positive refractive power,

wherein the following Conditions (1) to (4) are satisfied;

−

25<

(F₁/F)<

−

15 

 

Condition (1);

5<

(F₂/F)<

6 

 

Condition (2);

35<

(F₃/F)<

40 

 

Condition (3); and

−

4.5<

(F₄/F)<

−

3.5 

 

Condition (4),

where;

F is the focal length of the wide-angle projection lens module;

F₁ is the focal length of the first lens group;

F₂ is the focal length of the second lens group;

F₃ is the focal length of the third lens group; and

F₄ is the focal length of the fourth lens group.

14. The wide-angle projection lens module of claim 13, wherein the following Conditions (5) further satisfies:

|Diameter of the image circle/F|>

4.5 

 

Condition (5),

where,

Diameter of the image circle is equal to 2 times that of a rear image height.

15. A wide-angle projection lens module comprising the following components in sequential order from an output side:

a first lens group with a convex aspheric reflective surface;

a second lens group of negative refractive power having at least one aspheric surface;

a third lens group of substantially zero refractive power, wherein an aperture stop lies of the wide-angle projection lens module lies within or near the third lens group; and

a fourth lens group of positive refractive power,

wherein the following Conditions (1) to (4) are satisfied;

15<

|F₁/F|<

25 

 

Condition (1);

5.0<

|F₂/F|<

7.0 

 

Condition (2);

35<

F₃/F|<

40 

 

Condition (3); and

4.0<

|F₄/F|<

4.5 

 

Condition (4),

where;

F is the focal length of the wide-angle projection lens module;

F₁ is the focal length of the first lens group;

F₂ is the focal length of the second lens group;

F₃ is the focal length of the third lens group; and

F₄ is the focal length of the fourth lens group.

16. The wide-angle projection lens module of claim 15, wherein the following Conditions (5) further satisfies:

angle between any chief ray and optical axis<

5 degrees 

 

Condition (5).

17. The wide-angle projection lens module of claim 15, wherein the lens is incorporated in a front projection display system.

18. The wide-angle projection lens module of claim 15, wherein the first lens group comprises a single rotational symmetrical convex aspheric folding mirror.

19. The wide-angle projection lens module of claim 15, wherein the second lens group comprises a first meniscus shaped lens element nested with a second meniscus shaped lens element.

20. The wide-angle projection lens module of claim 15, wherein the third lens group comprises at least two cement lens elements.

21. The wide-angle projection lens module of claim 15, wherein the fourth lens group comprises at least four positive lens elements, and an average Abbe value of all the positive lens elements of the fourth lens group is greater than 70.

22. The wide-angle projection lens module of claim 21, wherein the average Abbe value of all the positive lens elements of the fourth lens group is greater than 80.

23. An optical engine for a display device, comprising:

a light source, providing a light beam;

a relay optical system; and

a wide-angle projection lens module, comprising;

a first lens group, having a convex folding aspheric mirror disposed at an output side of the wide-angle projection lens module; and

a second lens group of negative refractive power, having at least one aspheric surface, wherein the light beam travels from the light source, passing the relay optical system and the wide-angle projection lens module to generate an output image at a half field angle of at least about 65°

, and the output image has substantially no distortion.

24. The optical engine of claim 23, wherein the output image has a half field angle of at least about 60°

.

25. The optical engine of claim 23, wherein the output image has a half field angle of at least about 55°

.

26. The optical engine of claim 23, wherein a projection image size of the output image is at least 50 inches (diagonal measurement), and requires substantially no keystone correction.

27. The optical engine of claim 23, wherein a projected image format of the output image is one of a 4×

3 format, a 5×

3 format and a 16×

9 format.

28. The optical engine of claim 23, wherein the optical engine is incorporated in a front projection display system.

29. The optical engine of claim 23, wherein the optical engine is incorporated in a rear projection display system.

30. The optical engine of claim 23, wherein the second lens group comprises a first lens element of negative refractive power and a second lens element having an aspheric surface, wherein a ratio of a focal length of the second lens group to a focal length of the wide-angle projection lens module (F₂/F) has the relationship:

5<

F₂/F<

6.

31. The optical engine of claim 30, wherein the wide-angle projection lens module further comprises a third lens group disposed adjacent the second lens group, the third lens group has refractive power, and a ratio of a focal length of the third lens group to a focal length of the wide-angle projection lens module (F₃/F) has the relationship:

35<

F₃/F<

40.

32. The optical engine of claim 31, wherein an aperture stop of the wide-angle projection lens module is located at about the third lens group.

33. The optical engine of claim 31, wherein the wide-angle projection lens module further comprises a fourth lens group having a positive refractive power disposed adjacent the third lens group, and a ratio of a focal length of the fourth lens group to a focal length of the wide-angle projection lens module (F₄/F) has the relationship:

−

4.5<

F₄/F<

−

4.

34. The optical engine of claim 23, wherein the second lens group comprises a first lens element of negative refractive power and a second lens element of substantially uniform thickness.

35. The optical engine of claim 23, further comprising:

a third lens group of substantially zero refractive power and wherein an aperture stop of the wide-angle projection lens module lies within or near the third lens group; and

a fourth lens group of positive refractive power,

wherein the following Conditions (1) to (4) are satisfied;

15<

|F₁/F|<

25 

 

Condition (1);

5.0<

|F₂/F|<

7.0 

 

Condition (2);

35<

|F₃/F|<

40 

 

Condition (3); and

4.0<

|F₄/F|<

4.5 

 

Condition (4),

where;

F is the focal length of the wide-angle projection lens module;

F₁ is the focal length of the first lens group;

F₂ is the focal length of the second lens group;

F₃ is the focal length of the third lens group; and

F₄ is the focal length of the fourth lens group.

36. The optical engine of claim 35, wherein the second lens group comprises a first lens element of negative refractive power and a second lens element of substantially uniform thickness throughout.

37. A wide-angle projection lens module, comprising:

a reflective convex aspheric mirror; and

a refractive lens group of positive refractive power, wherein the following Conditions (1) to (2) are satisfied;

15<

|F_reflective/F|<

25 

 

Condition (1); and

1.5<

|F_refractive/F|<

2.0 

 

Condition (2),

where;

F is a focal length of the wide-angle projection lens module;

F_refractive is a focal length of the reflective convex mirror; and

F_refractive is a focal length of the refractive lens group.

38. The wide-angle projection lens module as claimed in claim 37, wherein a Condition (3) further satisfies:

|Diameter of the image circle/F|>

4.5 

 

Condition (3),

where,

Diameter of the image circle is equal to 2 times that of a rear image height.

39. The wide-angle projection lens module as claimed in claim 37, wherein a Condition (3) further satisfies:

|d/F|>

10 

 

Condition (3),

where,

d is a distance between the reflective convex mirror and a first refractive lens (L2) surface.