Projection display apparatus

• US 9,235,111 B2
• Filed: 09/27/2013
• Issued: 01/12/2016
• Est. Priority Date: 10/01/2012
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Yamaguchi, Yutaka
• Primary Examiner(s): Kim, Richard
• Application Number:
  US14/039,565
• Publication Number:
  US 20140092320A1
• Time in Patent Office: 837 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A projection display apparatus includes a polarization beam splitter, a first phase compensation plate including two layers, and a light modulator. Each layer has a constant axial angle, and an optical axis of each layer inclines with respect to the x axis in an xz plane. The axial angle of the layer closer to the polarization beam splitter among the two layers is larger than the axial angle of the layer farther from the polarization beam splitter. 20°≦θmax−θmin≦80° is satisfied where θmax is a maximum value of the axial angle and θmin is a minimum value of the axial angle. 40°≦θave≦70° is satisfied where θave is an average value of axial angles of the two layers.

Claims

1. A projection display apparatus configured to project an image onto a target surface, the projection display apparatus comprising:

a polarization beam splitter having a polarization splitting plane configured to transmit first polarized light of incident light and to reflect second polarized light of the incident light which has a polarization direction perpendicular to that of the first polarized light;

a first phase compensation plate including two layers and configured to provide a retardance which is larger than a sum of λ

/4 to polarized light having a wavelength λ

from the polarization beam splitter; and

a light modulator configured to modulate light from the first phase compensation plate according to an image signal,

wherein when a z axis is set to a normal direction of an incident plane of the light modulator, a y axis is set to a direction perpendicular to the z axis and a normal of the polarization splitting plane, an x axis is set to a direction perpendicular to the z axis and the y axis, and an axial angle is defined as an angle of 90°

or less between each of optical axis of two layers of the first phase compensation plates and the z axis, each layer has a constant axial angle, and the optical axis of each layer inclines with respect to the x axis in an xz plane,

wherein the axial angle of the layer closer to the polarization beam splitter among the two layers is larger than the axial angle of the layer farther from the polarization beam splitter,

wherein the following conditional expression is satisfied,

20°

≦

θ

max−

θ

min≦

80°

where θ

max is a maximum value of the axial angle and θ

min is a minimum value of the axial angle,

wherein the following conditional expression is satisfied,

40°

≦

θ

ave≦

70°

where θ

ave is an average value of axial angles of the two layers.

2. A projection display apparatus configured to project an image onto a target surface, the projection display apparatus comprising:

a polarization beam splitter having a polarization splitting plane configured to transmit first polarized light of incident light and to reflect second polarized light of the incident light which has a polarization direction perpendicular to that of the first polarized light;

a first phase compensation plate including three layers or more and configured to provide a retardance which is larger than a sum of λ

/4 to polarized light having a wavelength λ

from the polarization beam splitter; and

a light modulator configured to modulate light from the first phase compensation plate according to an image signal,

wherein when a z axis is set to a normal direction of an incident plane of the light modulator, a y axis is set to a direction perpendicular to the z axis and a normal of the polarization splitting plane, an x axis is set to a direction perpendicular to the z axis and the y axis, and an axial angle is defined as an angle of 90°

or less between each of optical axis of two layers of the first phase compensation plates and the z axis, each layer has a constant axial angle, and the optical axis of each layer inclines with respect to the x axis in an xz plane, the three layers or more containing different axial angles,

wherein the following conditional expression is satisfied,

20°

≦

θ

max−

θ

min≦

80°

where θ

max is a maximum value of the axial angle and θ

min is a minimum value of the axial angle,

wherein the following conditional expression is satisfied,

40°

≦

θ

ave≦

70°

where θ

ave is an average value of axial angles of the three layers or more.

3. The projection display apparatus according to claim 2, wherein the following conditional expression is further satisfied:

40°

≦

θ

max−

θ

min≦

70°

.

4. The projection display apparatus according to claim 2, wherein the following conditional expression is further satisfied:

55°

≦

θ

ave≦

70°

.

5. The projection display apparatus according to claim 2, wherein the following conditional expression is further satisfied:

65°

≦

θ

max≦

90°

.

6. The projection display apparatus according to claim 2, wherein the following conditional expression is further satisfied:

10°

≦

θ

min≦

50°

.

7. The projection display apparatus according to claim 2, wherein the axial angles of the three or more layers are configured so as to monotonously increase or decrease as a distance from the polarization beam splitter increases in the z axis.

8. The projection display apparatus according to claim 2, wherein the first phase compensation plate is made of a liquid crystal material.

9. The projection display apparatus according to claim 2, further comprising a plurality of image display elements each configured to modulate and reflect the incident light and to correspond to the incident light in different wavelength bands,

wherein the first phase compensation plate is arranged between at least one of the plurality of image display elements and the polarization beam splitter.

10. The projection display apparatus according to claim 9, wherein the first phase compensation plate is arranged on an optical path of green colored light.

11. The projection display apparatus according to claim 2, further comprising:

a plurality of image display elements configured to modulate and reflect the incident light and to correspond to the incident light in different wavelength bands; and

a second phase compensation plate arranged between the polarization beam splitter and at least one of the plurality of image display elements, and provided with a retardance of λ

/16 or more and λ

/4 or less with respect to light having a wavelength λ

.

12. The projection display apparatus according to claim 11, further comprising:

a plurality of image display elements configured to modulate and reflect the incident light and to correspond to the incident light in different wavelength bands; and

a third phase compensation plate arranged between the polarization beam splitter and at least one of the plurality of image display elements and provided with a refractive index anisotropy opposite to refractive index anisotropy of the image display element.

13. The projection display apparatus according to claim 2, wherein the polarization beam splitter is a prism type polarization beam splitter.

14. The projection display apparatus according to claim 2, further comprising a polarizer configured to transmit the first polarized light and to reflect the second polarized light,

wherein the first phase compensation plate is arranged between the polarizer and the polarization beam splitter.

15. The projection display apparatus according to claim 2, further comprising a projection optical system configured to project the image onto the target surface,

wherein the phase compensation plate is arranged on an optical path between the polarization beam splitter and the projection optical system.

16. The projection display apparatus according to claim 2, further comprising a projection optical system configured to project the image onto the target surface,

wherein the phase compensation plate is arranged on a light source side of the polarization beam splitter.

17. A projection display apparatus configured to project an image onto a target surface, the projection display apparatus comprising:

a polarization beam splitter having a polarization splitting plane configured to transmit first polarized light of incident light and to reflect second polarized light which has a polarization direction perpendicular to that of the first polarized light;

a dichroic film configured to reflect or to transmit light beams in different wavelength bands;

a first phase compensation plate including two layers and configured to provide a retardance which is larger than a sum of λ

/4 to polarized light having a wavelength λ

of the polarization beam splitter; and

a light modulator configured to modulate light from the first phase compensation plate according to an image signal,

wherein when a z axis is set to a normal direction of an incident plane of the light modulator, a y axis is set to a direction perpendicular to the z axis and a normal of the polarization splitting plane, an x axis is set to a direction perpendicular to the z axis and the y axis, and an axial angle is defined as an angle of 90°

or less between each of optical axis of two layers of the first phase compensation plates and the z axis, each layer has a constant axial angle, and the optical axis of each layer inclines with respect to the x axis in an xz plane,

wherein the axial angle of the layer closer to the polarization beam splitter among the two layers is larger than the axial angle of the layer farther from the polarization beam splitter,

wherein the following conditional expression is satisfied,

20°

≦

θ

max−

θ

min≦

80°

where θ

max is a maximum value of the axial angle and θ

min is a minimum value of the axial angle,

wherein the following conditional expression is satisfied,

40°

≦

θ

ave≦

70°

where θ

ave is an average value of axial angles of the two layers.

18. A projection display apparatus configured to project an image onto a target surface, the projection display apparatus comprising:

a polarization beam splitter having a polarization splitting plane configured to transmit first polarized light of incident light and to reflect second polarized light which has a polarization direction perpendicular to that of the first polarized light;

a dichroic film configured to reflect or to transmit light beams in different wavelength bands;

a first phase compensation plate including three layers or more and configured to provide a retardance which is larger than a sum of λ

/4 to polarized light having a wavelength λ

from the polarization beam splitter; and

a light modulator configured to modulate light from the first phase compensation plate according to an image signal,

wherein when a z axis is set to a normal direction of an incident plane of the light modulator, a y axis is set to a direction perpendicular to the z axis and a normal of the polarization splitting plane, an x axis is set to a direction perpendicular to the z axis and the y axis, and an axial angle is defined as an angle of 90°

or less between each of optical axis of two layers of the first phase compensation plates and the z axis, each layer has a constant axial angle, and the optical axis of each layer inclines with respect to the x axis in an xz plane, the three layers or more containing different axial angles,

wherein the following conditional expression is satisfied,

20°

≦

θ

max−

θ

min≦

80°

where θ

max is a maximum value of the axial angle and θ

min is a minimum value of the axial angle,

wherein the following conditional expression is satisfied,

40°

≦

θ

ave≦

70°

where θ

ave is an average value of axial angles of the three layers or more.

19. The projection display apparatus according to claim 18, wherein the phase compensation plate is arranged between the dichroic film and the polarization beam splitter.

20. The projection display apparatus according to claim 18, further comprising a plurality of image display elements each configured to modulate and reflect the incident light and to correspond to the incident light in different wavelength bands,

wherein the phase compensation plate is arranged between the dichroic film and at least one of the plurality of image display elements.