More reliable monochromatic stereoscopic image projector

Patent metadata

Field	Value
Publication number	US-10666932-B2
Application number	US-201715475061-A
Country	US
Kind code	B2
Filing date	Mar 30, 2017
Priority date	Apr 1, 2016
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

The general field of the invention is that of monochromatic stereoscopic image projectors including two light sources that illuminate two imagers, the radiation of the two light sources having a spectral distribution centred on a central wavelength, the first imager and the second imager being connected to a generator of stereoscopic image pairs. The image projector includes a dichroic separating filter that transmits the portion of the spectrum below the central wavelength and that reflects the portion of the spectrum above this central wavelength. The first light source and the second light source are arranged symmetrically on either side of the dichroic separating filter. The image projector operates cyclically, each cycle including two alternations. Each alternation consists in changing the emission source and in switching to the two displays the left and right images emitted by the generator of image pairs.

First claim

What is claimed is:

1. Monochromatic stereoscopic image projector including a first light source, a second light source, a first imager and a second imager, the radiation of the two light sources having the same spectral distribution centred on a central wavelength, the first imager and the second imager being connected to a generator of stereoscopic image pairs, each pair comprising what is called a “left” image and what is called a “right” image;
wherein:
the image projector includes a dichroic separating filter that transmits the portion of the spectrum emitted by the light sources below the central wavelength and that reflects the portion of the spectrum emitted by the light sources above the central wavelength, or vice versa;
the first light source and the second light source are arranged symmetrically on either side of the dichroic separating filter and are arranged so as to illuminate the first and the second imager;
the image projector operates cyclically, each cycle including two alternations,
in the first alternation, the image generator emits a first pair of stereoscopic images including a first left image and a first right image, the first left image being displayed by the first display and the first right image being displayed by the second display, the first light source is activated and the second light source is turned off,
in the second alternation, the image generator emits a second pair of stereoscopic images including a second left image and a second right image, the second left image being displayed by the second display and the second right image being displayed by the first display, the first light source is turned off and the second light source is activated, and
whatever the alternation, the left stereoscopic image is always emitted and the right stereoscopic image is always emitted.

2. Monochromatic stereoscopic image projector according to claim 1 , wherein the first light source and the second light source are light-emitting diodes, the central wavelength being located at about 530 nanometres.

3. Monochromatic stereoscopic image projector according to claim 1 , wherein the frequency of the cycle is comprised between 100 Hz and 400 Hz.

4. Monochromatic stereoscopic image projector according to claim 1 , wherein the first display and the second display are DMD micromirror displays.

5. Displaying system including means for generating stereoscopic images of a preset object, a device for displaying said stereoscopic images including a stereoscopic image projector and a semi-transparent screen and a pair of stereoscopic glasses, the means for generating stereoscopic images, the displaying device, the semi-transparent screen and the pair of stereoscopic glasses being arranged so that the stereoscopic image of the preset object appears, through the stereoscopic glasses, at a preset distance from the semi-transparent screen, wherein
the stereoscopic image projector comprises a monochromatic stereoscopic image projector including a first light source, a second light source, a first imager and a second imager, the radiation of the two light sources having the same spectral distribution centred on a central wavelength, the first imager and the second imager being connected to a generator of stereoscopic image pairs, each pair comprising what is called a “left” image and what is called a “right” image;
wherein:
the image projector includes a dichroic separating filter that transmits the portion of the spectrum emitted by the light sources below the central wavelength and that reflects the portion of the spectrum emitted by the light sources above the central wavelength, or vice versa;
the first light source and the second light source are arranged symmetrically on either side of the dichroic separating filter and are arranged so as to illuminate the first and the second imager;
the image projector operates cyclically, each cycle including two alternations,
in the first alternation, the image generator emits a first pair of stereoscopic images including a first left image and a first right image, the first left image being displayed by the first display and the first right image being displayed by the second display, the first light source is activated and the second light source is turned off,
in the second alternation, the image generator emits a second pair of stereoscopic images including a second left image and a second right image, the second left image being displayed by the second display and the second right image being displayed by the first display, the first light source is turned off and the second light source is activated,
the pair of glasses includes a first filter placed in front of the right eye and a second filter placed in front of the left eye, the first filter transmitting all of the spectrum except for the portion of the spectrum emitted by the light sources below the central wave wavelength and the second filter transmitting all of the spectrum except for the portion of the spectrum emitted by the light sources above the central wave wavelength, and
whatever the alternation, the left stereoscopic image is always emitted and the right stereoscopic image is always emitted.

6. Displaying system according to claim 5 , wherein the system includes means for detecting the relative position of the pair of glasses with respect to the position of the semi-transparent screen and means for computing the stereoscopic images so that the position of the stereoscopic image of the object is fixed in a preset coordinate system and is independent of the position of the stereoscopic glasses.

7. Displaying system according to claim 5 , wherein the preset distance is comprised between a few centimetres and optical infinity.

8. Displaying system according to claim 5 , wherein the displaying system is an aircraft cockpit system.

9. Monochromatic stereoscopic image projector according to claim 1 , wherein the light sources are light-emitting diodes and their control current is in pulsed mode with a peak current at least two times higher than that of the continuous mode.

10. Displaying system according to claim 5 , wherein the light sources are light-emitting diodes and their control current is in pulsed mode with a peak current at least two times higher than that of the continuous mode.

Assignees

• Thales Sa

Inventors

• Coni Philippe
• Gueguen Aude
• Grossetete Matthieu

Classifications

• G02B27/0101

  characterised by optical features (G02B27/0172 takes precedence) · CPC title

• H04N13/341

  using temporal multiplexing · CPC title

• H04N13/279

  the virtual viewpoint locations being selected by the viewers or determined by tracking · CPC title

• G02B30/23

  using wavelength separation, e.g. using anaglyph techniques · CPC title

• H04N2213/008

  Aspects relating to glasses for viewing stereoscopic images · CPC title