PROJECTION UNIT HAVING SPECKLE SUPPRESSION DEVICE BASED ON PIEZOELECTRIC ACTUATING

• US 20100141898A1
• Filed: 12/03/2009
• Published: 06/10/2010
• Est. Priority Date: 12/10/2008
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: MOUSSA, HASSAN
• Granted Patent: US 8,500,287 B2
• Time in Patent Office: Days
• US Class Current: 353/38
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A projection unit comprising a coherent light source such as a laser diode and a beam shaping element forming a light beam which is directed towards a display, characterized in that it comprises a laser speckle suppression device which is positioned between the laser source and the display and wherein the laser speckle suppression device is a diffusing element actuated randomly by a piezoelectric vibrating structure.

Claims

1. A projection unit comprising a coherent light source and a beam shaping element forming a light beam which is directed towards a display, wherein the projection unit comprises a laser speckle suppression device which is positioned between the light source and the display and wherein the laser speckle suppression device is a diffusing element actuated randomly by a vibrating structure.

2. The projection unit of claim 1, wherein the vibrating structure is arranged with regards to the diffusing element so as to generate a composite vibration movement including displacement of the diffusing element along an axis substantially parallel to the light beam direction in order to generate different wave fronts with different speckle characteristics on the display.

3. The projection unit of claim 2, wherein the composite vibration movement includes a pivoting movement of the diffusing element along an axis substantially orthogonal to the light beam direction.

4. The projection unit of claim 1, wherein the laser speckle suppression device includes a metallic structure with piezoelectric elements forming the vibrating structure, the diffusing element being mounted on the metallic structure to be actuated.

5. The projection unit of claim 1, wherein the laser speckle suppression device includes a quartz plate forming the diffusing element and the diffusing element is actuated by electrodes deposited on opposite sides of the quartz plate.

6. The projection unit of claim 5, wherein the quartz plate includes a diffusion layer.

7. The projection unit of claim 1, wherein the vibrating structure is mounted on a printed circuit board, and the printed circuit board comprises an electronic control unit to control the laser speckle suppression device.

8. A head-up display including a projection unit comprising a coherent light source and a beam shaping element forming a light beam which is directed towards a display, wherein the projection unit comprises a laser speckle suppression device which is positioned between the light source and the display and wherein the laser speckle suppression device is a diffusing element actuated randomly by a vibrating structure.

9. A head-up projection apparatus for a vehicle having a windshield positioned for reflection of a display image off a windshield surface into a vehicle operator line of sight, said display apparatus comprising:

a laser diode operative to provide a source of coherent light;

a display spaced from said laser diode;

a beam shaping element operative to transform said coherent light into a laser light beam, and directing said light beam toward said display; and

a laser speckle suppression device disposed between said beam shaping element and said display inline with said laser light beam, said laser speckle suppression device comprising

a substantially transparent quartz plate disposed generally normally to and in register with said laser light beam,

a diffusion layer deposited on a surface of said quartz plate,

a rigid metallic frame structure configured to support said quartz plate as a cantilever for reciprocating displacement about an axis orthogonal, to said laser light beam,

at least one piezoelectric plate fixed to the rigid frame structure and/or the quartz plate, and

an electronic oscillator in-circuit with said at least one piezoelectric plate, said oscillator operative to selectively energize said piezoelectric plate and thereby effect vibration of said quartz plate and rigid frame structure at a desired frequency and a desired vibration mode.

10. The head-up projection apparatus of claim 9, wherein said electronic oscillator comprises a substrate or printed circuit board configured to support said laser speckle suppression device.