Projection optical system

• US 8,113,667 B2
• Filed: 02/25/2008
• Issued: 02/14/2012
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Inventors: Hayashi, Kohtaro, Ohzawa, Soh, Imaoka, Masayuki, Yamada, Keiko
• Primary Examiner(s): Epps, Georgia Y
• Assistant Examiner(s): CHOWDHURY, SULTAN U.
• Application Number:
  US12/529,242
• Publication Number:
  US 20100118281A1
• Time in Patent Office: 1,450 Days
• Field of Search: 353/30, 353/31, 353/37, 353/78, 353/79, 353/98, 353/99, 353/101, 359/726, 359/727, 359/728, 359/729, 359/730, 359/731, 359/732, 359/733, 359/734, 359/735, 359/736, 359/649, 359/650, 359/651, 398/139
• US Class Current: 353/99
• CPC Class Codes: G02B 17/0816 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066

Abstract

A projection optical system satisfies a conditional formula: 0.01<{(tan θf1−tan θf2)−(tan θn1−tan θn2)}·(β2/β1)<0.20 where the direction of a normal to and the direction of a long side of the screen of the screen surface are referred to as a “z-direction” and an “x-direction”, respectively, the x-z plane component of the angle of incidence with respect to the screen surface is referred to as an “incident angle θ” and when, among rays that pass through the center of an aperture and that are incident on the ends of the upper and lower sides of the screen of the screen surface, the incident angle θ of rays whose incident angle θ is larger is referred to as “θf” and the incident angle θ of rays whose incident angle θ is smaller is referred to as “θn”, θn and θf2 respectively represent, when the absolute value of a projection magnification is the highest or lowest during focus adjustment, the incident angle θf, θn1 and θn2 respectively represent, when the absolute value of the projection magnification is the highest or lowest during focus adjustment, the incident angle θn, and β1 and β2 respectively represent the maximum and minimum values of the projection magnification during focus adjustment (except that β1 and β2 respectively represent, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is the highest or lowest).

Claims

1. A projection optical system that receives light from a display device surface and enlarges and projects a display image thereon obliquely onto a screen surface and that varies a projection distance to a screen to display images of different projection magnifications, the projection optical system comprising:

one or more reflective surfaces having an optical power between the display device surface and the screen surface,

wherein focus is adjusted by moving at least one optical device having an optical power, and conditional formula (1)′

below is satisfied;

0.02<

{(tan θ

f1−

tan θ

f2)−

(tan θ

n1−

tan θ

n2)}·

(β

2/β

1)<

0.20 

 

(1)′

where, when a screen of the display device surface is rectangular in shape, a direction of a normal to the screen of the screen surface is referred to as a “

z-direction”

, a direction of a long side of the screen of the screen surface is referred to as an “

x-direction”

, an x-z plane component of an angle of incidence with respect to the screen surface is referred to as an “

incident angle θ

(°

)” and

among rays that pass through a center of an aperture and that are incident on ends of upper and lower sides of the screen of the screen surface, the incident angle θ

of rays whose incident angle θ

is larger is referred to as “

θ

f” and

the incident angle θ

of rays whose incident angle θ

is smaller is referred to as “

θ

n”

,

θ

f1 represents, when an absolute value of a projection magnification is highest during focus adjustment, the incident angle θ

f,

θ

f2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the incident angle θ

f,

θ

n1 represents, when the absolute value of the projection magnification is highest during focus adjustment, the incident angle θ

n,

θ

n2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the incident angle θ

n,

β

1 represents a maximum value of the projection magnification during focus adjustment (except that β

1 represents, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is highest) and

β

2 represents a minimum value of the projection magnification during focus adjustment (except that β

2 represents, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is lowest).

2. The projection optical system of claim 1, wherein conditional formula (2) below is satisfied:

38<

θ

f<

80 

 

(2).

3. The projection optical system of claim 2, wherein a distance from an exit pupil of rays incident on the screen at the incident angle θ

f to the screen is shorter than a distance from an exit pupil of rays incident on the screen at the incident angle θ

n to the screen.

4. The projection optical system of claim 1, wherein conditional formula (3) below is satisfied:

1<

{(δ

1+δ

2)/(2·

P1)}·

|β

1|<

30 

 

(3)

where, when, among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of the aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment,

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

5. The projection optical system of claim 1, wherein conditional formula (3)′

below is satisfied;

6.03{(δ

1+δ

2)/(2·

P1)}·

|β

1|<

30 

 

(3)′

where, when, among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of the aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment,

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

6. The projection optical system of claim 1, wherein conditional formula (4) below is satisfied:

160<

(x1/P1)·

|β

1|<

500 

 

(4)

where, when among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of an aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment, and

x1 represents a half value of a width of the screen in the x-direction on the screen surface when the absolute value of the projection magnification is highest during focus adjustment.

7. The projection optical system of claim 1, wherein conditional formula (5) below is satisfied:

−

0.02<

{(δ

1−

δ

2)β

2}/{(δ

1+δ

2)β

1}<

0.2 

 

(5)

where

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

8. The projection optical system of claim 1, wherein conditional formula (5)′

below is satisfied;

0.0090≦

{(δ

1−

δ

2)β

2}/{(δ

1+δ

2)β

1}<

0.2 

 

(5)′

where

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

9. The projection optical system of claim 1, further comprising:

at least one refractive optical device having an optical power.

10. The projection optical system of claim 1, wherein rotationally symmetrical axes of at least two optical devices coincide.

11. The projection optical system of claim 1, wherein at least one reflective surface is moved in the focus adjustment.

12. The projection optical system of claim 1, wherein at least one refractive optical device is moved in the focus adjustment.

25. A projection image display apparatus comprising:

a display device forming a two-dimensional image and the projection optical system of claim 1.

13. A projection optical system that receives light from a display device surface and enlarges and projects a display image thereon obliquely onto a screen surface and that varies a projection distance to a screen to display images of different projection magnifications, the projection optical system comprising:

one or more reflective surfaces having an optical power between the display device surface and the screen surface,

wherein focus is adjusted by moving at least one optical device having an optical power, and conditional formula (1)′

below is satisfied within at least a range specified by a formula “

1.3≦

β

1/β

2≦

1.8”

;

0.02<

{(tan θ

f1−

tan θ

f2)−

(tan θ

n1−

tan θ

n2)}·

(β

2/β

1)<

0.20 

 

(1)′

where, when a screen of the display device surface is rectangular in shape, a direction of a normal to the screen of the screen surface is referred to as a “

z-direction”

, a direction of a long side of the screen of the screen surface is referred to as an “

x-direction”

, an x-z plane component of an angle of incidence with respect to the screen surface is referred to as an “

incident angle θ

(°

)” and

among rays that pass through a center of an aperture and that are incident on ends of upper and lower sides of the screen of the screen surface, the incident angle θ

of rays whose incident angle θ

is larger is referred to as “

θ

f” and

the incident angle θ

of rays whose incident angle θ

is smaller is referred to as “

θ

n”

,

θ

f1 represents, when an absolute value of a projection magnification is highest during focus adjustment, the incident angle θ

f,

θ

f2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the incident angle θ

f,

θ

n1 represents, when the absolute value of the projection magnification is highest during focus adjustment, the incident angle θ

n,

θ

n2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the incident angle θ

n,

β

1 represents a maximum value of the projection magnification during focus adjustment (except that β

1 represents, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is highest) and

β

2 represents a minimum value of the projection magnification during focus adjustment (except that β

2 represents, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is lowest).

14. The projection optical system of claim 13, wherein conditional formula (2) below is satisfied:

38<

θ

f<

80 

 

(2).

15. The projection optical system of claim 14, wherein a distance from an exit pupil of rays incident on the screen at the incident angle θ

f to the screen is shorter than a distance from an exit pupil of rays incident on the screen at the incident angle θ

n to the screen.

16. The projection optical system of claim 13, wherein conditional formula (3) below is satisfied:

1<

{(δ

1+δ

2)/(2·

P1)}·

|β

1|<

30 

 

(3)

where, when, among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of the aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment,

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

17. The projection optical system of claim 13, wherein conditional formula (3)′

below is satisfied;

6.03≦

{(δ

1+δ

2)/(2·

P1)}·

|β

1|≦

30 

 

(3)′

where, when, among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of the aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment,

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

18. The projection optical system of claim 13, wherein conditional formula (4) below is satisfied:

160<

(x1/P1)·

|β

1|<

500 

 

(4)

where, when among rays that reach a center of the screen of the screen surface from a center of the screen of the display device surface, a ray passing through a center of an aperture is referred to as a “

pupil center ray”

, and a length of a normal falling perpendicularly on the screen surface from an intersection between a reflective surface that is located closest to the screen among the reflective surfaces having an optical power and the pupil center ray is the projection distance,

P1 represents the projection distance when the absolute value of the projection magnification is highest during focus adjustment, and

x1 represents a half value of a width of the screen in the x-direction on the screen surface when the absolute value of the projection magnification is highest during focus adjustment.

19. The projection optical system of claim 13, wherein conditional formula (5) below is satisfied:

−

0.02<

{(δ

1−

δ

2)β

2}/{(δ

1+β

2)β

1}<

0.2 

 

(5)

where

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

20. The projection optical system of claim 13, wherein conditional formula (5)′

below is satisfied;

0.0090≦

{(δ

1−

δ

2)β

2}/{(δ

1+δ

2)β

1}<

0.2 

 

(5)′

where

δ

1 represents, when the absolute value of the projection magnification is highest during focus adjustment, an absolute value of a difference between a distance from an exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and a distance from an exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface, and

δ

2 represents, when the absolute value of the projection magnification is lowest during focus adjustment, the absolute value of the difference between the distance from the exit pupil of rays incident on the ends of the upper side of the screen of the screen surface to the screen surface and the distance from the exit pupil of rays incident on the ends of the lower side of the screen of the screen surface to the screen surface.

21. The projection optical system of claim 13, further comprising:

at least one refractive optical device having an optical power.

22. The projection optical system of claim 13, wherein rotationally symmetrical axes of at least two optical devices coincide.

23. The projection optical system of claim 13, wherein at least one reflective surface is moved in the focus adjustment.

24. The projection optical system of claim 13, wherein at least one refractive optical device is moved in the focus adjustment.

26. A projection image display apparatus comprising:

a display device forming a two-dimensional image and the projection optical system of claim 13.