IMAGE PROJECTION APPARATUS

• US 20150116669A1
• Filed: 10/22/2014
• Published: 04/30/2015
• Est. Priority Date: 10/24/2013
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: KWON, Jaewook, YOON, Chanyoung, LIM, Jaehyuk, KIM, Jideok
• Granted Patent: US 10,205,917 B2
• Time in Patent Office: Days
• US Class Current: 353/33
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/04 Prisms
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3129 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 Class Codes: H04N 9/317 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

Abstract

An image projection image for projecting an image on a screen includes a light source, a scanning mirror and a prism. The light source includes laser diodes for emitting beams of different wavelengths. The scanning mirror reflects the beams radiated from the light source and projects the reflected beams. The prism is disposed at the rear of the scanning mirror to decenter the beams via the scanning mirror based on the wavelengths. In the image projection apparatus, the laser diodes are fixed to be vertically spaced apart from a reference height, corresponding to the wavelengths of the beams.

Claims

1. An image projection apparatus, comprising:

a light source configured to include laser diodes for emitting beams of different wavelengths;

a scanning mirror configured to reflect the beams radiated from the light source and project the reflected beams; and

a prism disposed at the rear of the scanning mirror to decenter the beams via the scanning mirror based on the wavelengths,

wherein the laser diodes are fixed to be vertically spaced apart from a reference height, corresponding to the wavelengths of the beams.

2. The image projection apparatus of claim 1, further comprising a base member configured to include mounting holes formed to have relative heights corresponding to the heights of the respective laser diodes.

3. The image projection apparatus of claim 2, wherein, when the beams of different wavelengths are incident on the prism along the same path at one point on the screen, the relative heights are determined based on differences in height between the beams incident on the surface of the scanning mirror.

4. The image projection apparatus of claim 3, wherein the relative height is less than 1 mm.

5. The image projection apparatus of claim 3, wherein the laser diodes are respectively disposed at positions parallel to those at which color beams irradiated from the laser diodes, the color beams being incident in a reverse direction on the prism from the one point on the screen are incident on the surface of the scanning mirror.

6. The image projection apparatus of claim 5, wherein the laser diodes include a red diode, a green diode and a blue diode.

7. The image projection apparatus of claim 6, wherein the red and blue diodes are disposed to be spaced apart in opposite directions to each other, using the height of the green diode as a reference height.

8. The image projection apparatus of claim 7, wherein the green diode is disposed at the reference height, the red diode is disposed higher than the reference height, and the blue diode is disposed lower than the reference height.

9. The image projection apparatus of claim 1, further comprising a collimating lens disposed at the front of the light source to convert the beams of the light source into parallel beams.

10. The image projection apparatus of claim 9, wherein the collimating lens is formed to adjust the focus of the light source by relatively moving from the light source.

11. The image projection apparatus of claim 10, wherein the laser diodes includes a green diode, a red diode and a blue diode, which have relative heights to each other, and

wherein the collimating lens is spaced apart from each laser diode to have a height difference with the laser diode, so that the collimating lenses respectively correspond to the optical axes of beams irradiated from the laser diodes having the relative heights to pass through the prism.

12. The image projection apparatus of claim 11, wherein the laser diodes are disposed to be spaced apart from each other to have relative height differences using, as a reference, a diode corresponding to any one of a plurality of colors constituting the laser diodes, and

wherein the relative height difference is changed depending on a difference between a wavelength corresponding to the color of the diode that becomes the reference among the laser diodes and a wavelength corresponding to a color constituting each of the other diodes.

13. The image projection apparatus of claim 12, wherein, as the difference between the wavelength corresponding to the color of the diode that becomes the reference among the laser diodes and the wavelength corresponding to the color constituting each of the other diodes increases, the relative height difference further increases.

14. The image projection apparatus of claim 9, wherein the collimating lens is a condensing lens.

15. The image projection apparatus of claim 9, further comprising a dichroic mirror configured to separate or mix the beams converted into parallel beams through the collimating lens.

16. The image projection apparatus of claim 15, wherein the surface of the dichroic mirror is coated, so that the degree of transmission of beams passing through the dichroic mirror is changed depending on wavelength of beams irradiated from the light source.

17. The image projection apparatus of claim 15, wherein the surface of the dichroic mirror is anti-reflection (AR) coated in order to minimize the reflexibility of the beams converted into the parallel beams through the collimating lens.

18. The image projection apparatus of claim 15, wherein the beams passing through the dichroic mirror are incident on the scanning mirror.

19. The image projection apparatus of claim 1, wherein the scanning mirror includes a permanent magnet and a coil, and is horizontally or vertically driven in an electromagnetic manner.

20. The image projection apparatus of claim 1, wherein the disposition heights of the laser diodes are determined based on differences in height between the beams incident on the surface of the scanning mirror.