Projection device

Patent metadata

Field	Value
Publication number	US-10754234-B2
Application number	US-201816203800-A
Country	US
Kind code	B2
Filing date	Nov 29, 2018
Priority date	Nov 29, 2018
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

An embodiment of the present invention enables an improvement in image resolution. A projection device (1) includes: a light source (11); a MEMS mirror (14) which reflects and two-dimensionally scans the laser beam emitted from the light source; and a free-form lens (15) which changes focusing properties of the laser beam reflected by the scanning section such that, after propagation of the laser beam to a screen (20) onto which the image is to be projected, a shape of the laser beam when viewed on the screen has a first width that is shorter than a second width of the shape, the first width being along a horizontal direction corresponding to a primary scanning direction in which the MEMS mirror scans the laser beam, the second width being along a vertical direction.

First claim

The invention claimed is:

1. A projection device which scans a laser beam so as to project an image, the projection device comprising:
a light source which emits the laser beam;
a scanning section which reflects and two-dimensionally scans the laser beam emitted from the light source; and
a shape altering section which changes focusing properties of the laser beam reflected by the scanning section such that, after propagation of the laser beam to a projection surface onto which the image is to be projected, a shape of the laser beam when viewed on the projection surface has a first width that is shorter than a second width of the shape, the first width being along a first direction corresponding to a primary scanning direction in which the scanning section scans the laser beam, the second width being along a second direction orthogonal to the first direction;
wherein the shape altering section changes the focusing properties of the laser beam such that a ratio of the first width to the second width is not more than 1/2.

2. The projection device according to claim 1 , wherein a size of the laser beam is greater at the shape altering section than at the scanning section.

3. The projection device according to claim 1 , wherein the shape altering section is a free-form lens.

4. The projection device according to claim 2 , further comprising: a converging lens which focuses the laser beam emitted from the light source,
wherein positioning of the converging lens and the scanning section relative to each other is defined such that, before being incident on the scanning section, the laser beam outputted from the converging lens comes to a focus and then diverges, so that the size of the laser beam is greater at the shape altering section than at the scanning section.

5. The projection device according to claim 4 , wherein the converging lens focuses the laser beam only in the first direction.

6. The projection device according to claim 5 , wherein the converging lens is a cylindrical lens.

7. The projection device according to claim 4 , further comprising: a collimator lens which collimates the laser beam emitted from the light source,
the converging lens being provided so as to focus the laser beam after the laser beam has been outputted from the collimator lens.

8. The projection device according to claim 1 , wherein the shape altering section corrects distortion of the image.

9. A projection device which scans a laser beam so as to project an image, the projection device comprising:
a light source which emits the laser beam;
a scanning section which reflects and two-dimensionally scans the laser beam emitted from the light source; and
a shape altering section which changes a shape and a size of the laser beam reflected by the scanning section as viewed after the laser beam has propagated from the shape altering section to a projection surface upon which the projected image is to be viewed,
the size of the laser beam being greater at the shape altering section than at the scanning section,
the shape altering section being configured to decrease an angle of divergence of the laser beam in a first direction corresponding to a primary scanning direction in which the scanning section scans the laser beam;
wherein the shape altering section decreases the angle of divergence of the laser beam in the first direction such that a ratio of a first width to a second width is not more than 1/2,
the first width being the width, along the first direction, of the shape of the laser beam when viewed on the projection surface, the second width being the width, along a second direction orthogonal to the first direction, of the shape of the laser beam when viewed on the projection surface.

Assignees

• Sharp Kk

Inventors

• Roberts Peter John
• Fujii Noriaki
• Yamasawa Kengo

Classifications

• G02B26/105

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title

• H04N9/317 Primary

  Convergence or focusing systems (electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53) · CPC title

• H04N9/3129

  scanning a light beam on the display screen (scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161) · CPC title

• G02B26/128

  Focus control · CPC title

• G02B27/141

  using dichroic mirrors · CPC title