Polarization Conversion Unit, Polarization Conversion Device, and Projector

• US 20090015794A1
• Filed: 06/06/2008
• Published: 01/15/2009
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Sakai, Yohei
• Granted Patent: US 7,922,331 B2
• Time in Patent Office: Days
• US Class Current: 353/20
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: G03B 21/16 Cooling; Preventing overheating
• 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

Abstract

A polarization conversion unit includes a polarization splitting element array including a plurality of polarization splitting films for splitting the incident light beam into two types of linearly-polarized light beams, a plurality of reflecting films for reflecting either one of the linearly-polarized light beams obtained by the polarization splitting films, and a translucent member provided with the polarization splitting films and the reflecting films, a plurality of retardation plates each formed of a quartz crystal member and for converting a polarization axis of either one of the linearly-polarized light beams obtained by the polarization splitting films into a polarization axis of the other of the linearly-polarized light beams, and a spacer member having a predetermined thickness and for bonding end sections of the retardation plates to a light beam exit side of the translucent member.

Claims

1. A polarization conversion unit, comprising:

a polarization splitting element array including

a plurality of polarization splitting films disposed obliquely to an incident light beam and for splitting the incident light beam into two types of linearly-polarized light beams,

a plurality of reflecting films disposed in parallel alternately between the polarization splitting films and for reflecting either one of the linearly-polarized light beams obtained by the polarization splitting films, and

a translucent member provided with the polarization splitting films and the reflecting films;

a plurality of retardation plates each formed of a quartz crystal member and for converting a polarization axis of either one of the linearly-polarized light beams obtained by the polarization splitting films into a polarization axis of the other of the linearly-polarized light beams; and

a spacer member having a predetermined thickness and for bonding end sections of the retardation plates to a light beam exit side of the translucent member.

2. The polarization conversion unit according to claim 1,

wherein the spacer member is capable of reattachment of an attached object.

3. A polarization conversion device, comprising:

the polarization conversion unit according to claim 1; and

a fixing frame for fixing the polarization conversion unit,

wherein the fixing frame includes a first fixing frame disposed on a light beam entrance side of the polarization splitting element array, and a second fixing frame disposed on a light beam exit side of the retardation plates,

the first fixing frame has a fixing section for fixing the polarization element array, and

the second fixing frame fixes the retardation plates to the polarization splitting element array via an elastic member.

4. The polarization conversion device according to claim 3,

wherein the first fixing frame includes

a plurality of opening sections disposed at positions corresponding to the polarization splitting films and for allowing a light beam emitted from a light source to pass through, and

a plurality of light blocking sections disposed at positions corresponding to the reflecting films and for blocking a part of the light beam emitted from the light source.

5. The polarization conversion device according to claim 3,

wherein a size G of a gap between the polarization splitting element array and the retardation plates is in a range of 0.01≦

G≦

0.3 mm.

6. A projector comprising:

a light source;

the polarization conversion device according to claim 3;

a light modulation device for modulating a light beam emitted from the polarization conversion device based on image information; and

a projection optical device for projecting the light beam modulated by the light modulation device.

7. The projector according to claim 6,

wherein the first fixing frame includes

a plurality of opening sections disposed at positions corresponding to the polarization splitting films and for allowing a light beam emitted from a light source to pass through, and

a plurality of light blocking sections disposed at positions corresponding to the reflecting films and for blocking a part of the light beam emitted from the light source.

8. The projector according to claim 6,

wherein a size G of a gap between the polarization splitting element array and the retardation plates is in a range of 0.01≦

G≦

0.3 mm.