Television – Two-way video and voice communication – User positioning
Reexamination Certificate
1999-03-22
2001-04-03
Chan, Wing F. (Department: 2643)
Television
Two-way video and voice communication
User positioning
C348S014010, C348S373000
Reexamination Certificate
active
06211903
ABSTRACT:
FIELD OF INVENTION
This invention relates to video telephones and specifically to those in which an image capture device is supported by a foundation held adjacent to the user's head.
BACKGROUND
A video telephone combines an image capture device, an image display device, and a codec for coding and decoding the image.
Several different types of devices are available for the display of a video image. In U.S. Pat. No. 5,347,400 Hunter discloses a helmet-mounted display system for use in virtual reality applications. In U.S. Pat. No. 5,396,269 Gotoh discloses a display similar to that of a desktop PC. Gotoh combines the display with an image capture device which sits in stationary position on a desktop surface.
The image capture device is usually combined with a signal generator within a video camera. The video camera should be capable of capturing a facial image during the movement and gesturing of normal conversation. In particular, facial expressions should be captured during movement of the body. In U.S. Pat. No. 5,414,444, Britz discloses a communicator which incorporates a system of motors to orient the video imaging element. In U.S. Pat. No. 5,414,474 Kamada discloses an apparatus which tracks a moving body.
An additional feature of a video telephone should be the ability to make effective use of its limited communications bandwidth. In U.S. Pat. No. 5,371,534 Dagdeviren discloses a method of communicating audio and video signals using high speed digital ISDN telephone lines. ISDN is a mode of communication for the current invention, and U.S. Pat. No. 5,371,534 is hereby incorporated by reference. Even at the 128 kbps typical of ISDN circuits and using MPEG image compression, the bandwidth typically limits resolution below standard display resolutions and frame rates are typically reduced to 15 frames per second or less.
Furthermore, the ISDN circuits are not yet universally available, so the goal of ubiquitous video telephony cannot yet be realized through ISDN. According to Metcafe's Law, the value of a network increases with the square of the number of user's. By this measure the value of the network of current video telephones is far below its potential value.
The design of mobile devices and of devices using the more generally available plain-old-telephone-service (POTS) is even further constrained by limitations on communications bandwidth. Mobile devices have additional design constraints which limit their size, weight, and complexity.
Most current systems do not track movement of the user's face. Instead, the video camera has an oversized field of view to ensure that a shifting face remains within the image area. The is wasteful of the resolution of the video camera and of the communications bandwidth.
Even a complex system which can continually zoom, pan, and focus and can successfully track the user's movements has limitations. For example, by turning, a user can easily direct his face away from video camera so that his facial expressions cannot be captured by the video camera.
In the M.I.T. Media Laboratory Perceptual Computing Section Technical Report No 317, entitled “An Automatic System for Model-Based Coding of Faces” a compact representation of the face is described. In this system a parametric image model of the face is abstracted by recognizing features from a video image of the face. This parametric image model requires much less bandwidth than the original video image. However, they report that this parametric image model can be extracted only be when head tilts with respect to the video camera are limited to less than 15 degrees.
Current video telephones are further limited by a difficulty in establishing eye-to-eye contact. In most video telephones the camera is to the side or top of the display. Thus, the user can look directly at the camera or at the display, but not at both simultaneously.
The known devices do not satisfy all of the current requirements for a video telephone. There is the need for a video telephone with a video camera which can maintain an orientation and focus on a moving user. There is a need for a video telephone which can make effective use of the available bandwidth while remaining simple and compact.
OBJECTS AND ADVANTAGES
It is an object of this invention to:
a) provide a video telephone headset which can be configured as a telephone handset to enable it to be used for both voice communication and video pickup;
b) provide a very light, inexpensive and visually unobtrusive optical pickup component such as a mirror to direct a facial image toward a head-mounted video camera;
c) position the mirror such that it can capture the full facial expressions for video communications;
d) provide a mirror curved such that the image reflected to the video camera accurately corresponds to the original facial image;
e) shift the viewing perspective so that eye-to-eye contact can maintained through an off-center mirror;
f) configure a single video camera capable of capturing both the user's face and the user's field of view;
g) maintain the focus and image capture of the face while the user is moving;
h) maximize the potential for effective data compression by minimizing the movement of the camera with respect to the face;
i) maximize the use of available resolution by keeping the mirror and camera fixed with respect to the user's face;
j) eliminate the need for a camera operator or a tracking system to track a moving facial image;
k) eliminate the potential of the user inadvertantly turning away from the camera;
l) allow a user to participate in a videoconference hands-free or while walking;
m) allow the users to maintain eye-to-eye contact during a videoconference; and,
n) allow the mirror to retract so that a fully functional device can collapse to fit into a pocket.
It is a further object of this invention to minimize the field of view of the camera so that:
a) only the essential information consisting of the face and facial expression is captured;
b) the size of the display needed to view the image is reduced; and,
c) for a given sized display, a greater number of images in a group videoconference may be simultaneously displayed;
d) the reduced image may be resolved with a reduced number of pixels and represented with a reduced quantity of data.
It is a further object of this invention to reduce the quantity of data used to represent the image so that:
e) the computational requirements for the codec are reduced;
f) the transmission bandwidth requirements are reduced, so that a videoconference may be held through the universally available POTS rather than digital ISDN circuit;
g) the image quality transmitted through a given bandwidth may be enhanced with more color bitplanes or an increased frame rate;
h) the requirements for storage of a videoconference is reduced; and,
i) the storage requirements for a video telephone answering machine are reduced.
SUMMARY
A video telephone headset includes a video camera configured to capture an image of the user's face when the headset is held adjacent to the user's head.
In one embodiment the camera is oriented toward an image capture mirror located immediately in front of a user's face. The image capture mirror reflects the image of the user's face to the camera. The capture mirror may retract to allow the image capture device to capture the user's unobstructed field of view. The capture mirror may be curved in a convex manner such that a capture mirror of reduced diameter will reflect the image of the entire face.
A display may be positioned directly in front of and visible to the user during conversation. A display may be attached to the side of the headset and an image display mirror is positioned in front of the user's eye to provide an optical path between the eye and the display. A display may be contained within an eyepiece positioned in front of the user's eye. Alternatively, the display may be a separate component which may be fixed on a desk.
In one embodiment a audio pickup device and speaker are positioned on th
Cambridge Technology Development, Inc.
Chan Wing F.
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