Optics: image projectors – Structurally related projector and screen
Reexamination Certificate
2003-03-14
2004-08-31
Adams, Russell (Department: 2851)
Optics: image projectors
Structurally related projector and screen
C353S077000, C353S122000, C353S098000, C353S015000, C359S460000
Reexamination Certificate
active
06783247
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates generally to the display of video or computer generated images within a three dimensional volume of space through a configuration using a two-way mirror to superimpose an image displayed on a front projection screen with the potential of adding a camera in the line of sight of a life-size image of a person to achieve a perceived eye contact.
2. Description of Related Art
There is an increased need for advanced display systems that can improve communication through the display of prerecorded images that appear within a three dimensional setting for the purposes of advertising, product demonstrations, promotional activities, entertainment and various other applications. In addition to the display of prerecorded images, there is a need for displaying live images in the three dimensional setting for interacting with the imagery in real time.
The imagery to be displayed in the three dimensional setting may include prerecorded or live images of people at life-size or at a size appropriate to the purpose of the communication. For achieving lifelike interaction in real time, a camera can be placed in a position behind the plane of the appearance of the superimposed image within the three dimensional setting. By aligning the camera to the line of sight of the eye level of the generated life-size image, it is possible to achieve an apparent eye contact. This configuration has advantages over standard video conferencing, which does not achieve eye contact due to the placement of the camera above the displayed image of the person. With the economic conditions requiring cutbacks in travel budgets and the adverse effects of increased security to counteract terrorism, there is an increased need for an alternative to travel. This has generated a market need for systems that overcome the shortcomings of video conferencing, including providing eye contact and creating a greater sense of presence.
It has been shown in prior art as in
FIG. 1
that a video image of a person can be viewed as a reflected image off a two-way mirror
2
with a camera
3
positioned behind the two-way mirror in a position that matches the eye level of the displayed person. This configuration can result in the appearance of eye contact with the person displayed on the video image. Communications systems with eye contact have included displays using CRT monitors
4
or rear projection systems. The size of the monitor
4
has required that embodiments in this configuration have been bulky making them undesirable for usage in many applications, such as typical office workspaces.
FIG. 2
shows prior art of a video phone illustrated in U.S. Pat. No. 5,194,955. This configuration demonstrates the usage of a flat panel display
5
with a line of sight that is matched to a camera
3
behind a two-way mirror
2
. Even though flat panel displays minimize the bulk of a display system, they are very expensive for the size required to display a life-size image. This configuration results in the display of a flat image that will appear to be at the back of enclosure. For this reason this embodiment does not have the advantages of the appearance of images within the free space of a three dimensional setting.
Prior art U.S. Pat. Nos. 5,639,151 and 5,890,787 have attempted to resolve this issue by using a projector
6
to project an image through the two-way mirror
2
as illustrated in FIG.
3
. The configuration does achieve a larger image than is practical with a flat panel display, but causes numerous undesirable visual effects. Firstly, the two-way mirror
2
by definition only allows a portion of light to be transmitted while the rest is reflected. As a result, only a portion of the light projected through the two-way mirror
2
will actually reach the front projection screen
7
. Therefore, the brightness of the image on the front projection screen
7
is diminished, making the efficiency of the projection reduced. Secondly, a portion of the projected image is reflected off the two-way mirror
2
and shines directly into the lens of the camera
3
. This is due to the requirement that the image of the person to be viewed on the front projection screen
7
must be aligned with the line of sight of the camera
3
in order to achieve the apparent eye contact. This alignment necessitates that the camera
3
will view the reflection of the projected image
32
, which will cause a bright spot in the view to be transmitted to the person at the remote location and may cause a flare of light that would diminish the overall quality of the captured image. Thirdly, the projection of light on the two-way mirror
2
will brightly illuminate any dust or smudges on the glass surface of the two-way mirror
2
. The consequence of this illumination of the surface of the glass is that the image captured by the camera
3
is illuminated with this unwanted distraction from the view through the two-way mirror. This problem is accentuated by the fact that the projected image must be bright to pass through the two-way mirror
2
and the camera
3
must be set to an open aperture to expose for the portion of light that will pass through the two-way mirror. Fourthly, the front projection surface
7
is in a direct line of sight
30
of the user
1
, which is distracting from the intended purpose of making eye contact with the image displayed as the reflected image in the two-way mirror
2
. Fifthly, the front projection screen
7
is facing upward toward overhead room lighting (not shown), which will wash out the image with light and diminish the overall quality of the displayed image. This is particularly critical for achieving the perception of the image of the person as appearing to be within the three dimensional volume of space. The incoming video signal of the person in the remote location should be an image of the person with the background dropped out to black. It is imperative that this black is maintained as the image is displayed on the screen so that the superimposed image shows the person without any light in the area of the background. Otherwise the rectangular frame of the screen will appear, which will break the illusion of the person being with the free volume of the three dimensional setting. It is for this reason that any light falling on the surface of the screen
7
must be avoided, which is difficult to achieve with this embodiment. Sixthly, the image displayed on screen
7
is viewed to appear behind the two-way mirror
2
. Since there is equipment behind the two-way mirror
2
in the space where the reflected image would appear, it is not possible to view the image within a three dimensional setting. Therefore, the image generated by this invention is flat and does not have the potential to have the benefits of an image that appears to have three dimensional qualities in free space.
Prior art of patent WO97/11405 presents a configuration for theatrical production shown in
FIG. 4
, which illustrates the usage of a projection down onto a screen positioned on the floor. This shows the usage of a projected image in front of a two-way mirror
2
, which is made from a thin semi-reflective film, instead of a semi-reflective sheet of glass. This configuration achieves a large image without the problems incurred by projecting through the two-way mirror. However, there is a major disadvantage of this configuration in that the front projection screen
7
is facing upwards to overhead lighting (not shown). While this may be acceptable in a theatrical application where the room lighting can be controlled, it would not be acceptable in an office environment or a normal public location where overhead lighting would be bright. Furthermore, the position of the screen surface
7
below the two-way mirror
2
places the image in a direct line of sight
30
of the viewer
1
, which is distracting and takes away from the desired effect of creating the reflected image
10
appearing without revealing the source of the image.
Hence, there is a need for an improved system that addres
Adams Russell
Sever Andrew
Slater & Matsil L.L.P.
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