Audio-video recording of overhead projector based presentations

Optics: image projectors – Miscellaneous

Reexamination Certificate

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Details

C353S015000, C353S019000, C353S022000, C353S120000, C349S006000, C352S026000, C352S027000, C352S031000

Reexamination Certificate

active

06550922

ABSTRACT:

The present invention relates to the audio-video recording of overhead projector based presentations.
Presentations to an audience are often made by a presenter with the aid of an overhead projector (OHP). One type of OHP has an upward-facing horizontal clear glass plate which is back-illuminated by the projector by a white light source so that projected light is directed upwards through the projection plate. Another type of OHP has an upward-facing mirrored plate which is front-illuminated so that light projected downwards onto the mirror is reflected upwards by the mirror. An object on either type of plate is thus illuminated so that light passing through or to one side of the object is projected upwards and then laterally onto a viewing screen. All such OHP plates are referred to herein as “projection plates”.
In one type of presentation, the presenter lays a series of clear or translucent plastic sheets one at a time on the projection plate while giving a talk. The sheets may contain written information, drawings, graphs, photographs or any other type of visual information. Sometimes, the presenter may write on the sheets as part of the presentation. Such sheets are referred to herein as “OHP transparencies”.
In another type of presentation, an active matrix liquid crystal screen is placed on the projection plate. The screen may be connected to a personal computer which then sends signals to the screen to activate pixels of the liquid crystal screen to display computer generated images. When activated, the pixels act as light shutters to alter the amount and colour of light passing through the screen. Such active matrix light shutters are referred to herein as “electronic transparencies”.
OHP transparencies, electronic transparencies, and all other such objects which may be placed on an OHP projection plate as part of an audio-video presentation are referred to herein as “viewable objects”.
If a person wishes to make a recording of an OHP presentation, then it is quite straightforward to make an audio-only recording of the presenter's voice and to copy or print out paper images of the viewable objects, or to scan or capture these as computer-viewable images. However, a person listening to the audio recording while looking at the images may have difficulty in following the sequence of the images with the person's voice. In addition, such an audio-only recording may miss important information, such as the presenter writing on the viewable objects, presenting viewable objects out of sequence, or pointing to parts of the viewable objects on the projection plate or on the projection screen.
One way to deal with this problem is to make an audio-video recording of the presentation with a camcorder set up to capture images of both the presenter and the OHP images as projected onto a screen. This, however, is not entirely satisfactory, as the video resolution of such recordings, at least for inexpensive camcorders, is insufficient to capture each projected image with adequate resolution. Preferably such resolution should be at least about 300 dpi for an A4-sized viewable object. Such resolution may be achieved by training a video camera exclusively on a projected image, but such a recording uses a significant amount of storage on a video recording medium, which is inconvenient to deal with even though such generally static images can subsequently be compressed.
It is an object of the present invention to provide a more convenient apparatus and method for making an audio-video recording of an OHP based presentation.
According to the invention, there is provided an apparatus for making an audio-video recording of an OHP based presentation, comprising an audio microphone, a logging means for logging when a presenter changes a viewable object on an OHP, and a recording apparatus, wherein: the microphone generates an audio signal from the audio portion of the presentation; the logging means is activatable to generate a marker signal indicating the change of viewable object; and the recording apparatus receives the audio signal from the microphone and the marker signal from the logging means to record said signals as audio data and marker data so that audio data is correlated with the marker data.
Also according to the invention, there is provided a method of making an audio-video recording of an OHP based presentation, using an apparatus comprising an audio microphone, a logging means for logging when a presenter changes a viewable object on an OHP, and a recording apparatus, wherein the method comprises the steps of:
a) using the microphone to generate an audio signal from the audio portion of the presentation;
b) changing a viewable object on a projection plate, and activating the logging means to generate a marker signal indicating the change of viewable object; and
c) using the recording apparatus to record the audio signal from the microphone and the marker signal from the logging means as respectively audio data and marker data so that audio data is correlated with the marker data.
Changes in viewable objects may then at a later time be correlated with changes in the viewable objects during the presentations.
The data may be analogue data, but is preferably digital data, for example digitally compressed audio data, and digital data indicating the points in the audio data at which viewable objects were changed by the presenter.
The apparatus may then, for example, record respectively the audio portion of the presentation, and the times during the audio portion of the presentation when viewable objects are changed.
The logging means may be manually activated by the presenter, or another person, whenever the presenter advances to the next viewable object, for example by pressing a button. It is preferable, however, if the logging means is automatically activated whenever the presenter changes the viewable object.
The logging means may indicate simply that the presenter has moved on to the next slide. Preferably, the logging means is adapted to detect when a presenter places an overhead transparency on a projection plate and/or removes said transparency from a projection plate.
If the order of the slides is known, then the correct slides can later be correlated with the marker signals.
There may be times when the presenter will present slides in other than a predetermined sequential order, for example digressing to a previously shown slide. It is therefore helpful if the marker signal contains information regarding the identity of the viewable object.
In a preferred embodiment of the invention, the logging means includes a sensor to detect whether or not an OHP transparency has been placed on the projection plate.
The OHP transparencies may comprise a clear or translucent sheet of plastics material. Such sheets may include non-transparent or non-translucent borders, for example an opaque plastic border along one or more edges, or a paper frame. The sensor may then be arranged to detect such a border or frame, either from its physical properties, or its optical properties.
The logging means may comprise an OHP alignment device, adapted to be placed or affixed atop a projection plate. The alignment device then includes at least one alignment edge against which a corresponding straight edge of an OHP transparency may be brought. The sensor is then adapted to detect the presence of the OHP transparency as the OHP transparency is aligned against the alignment edge. The alignment edge may be a continuous, straight alignment edge.
The sensor may be an optical sensor that senses a change in optical radiation mediated by the OHP transparency. The mediation of optical radiation may be by means of transmission through or reflection or scattering from the OHP transparency towards the optical sensor, and the optical sensor may detect either visible light, or invisible light, particularly infra-red optical radiation.
The logging means may include an integral light source arranged to transmit optical radiation to the optical sensor through/from the OHP transparency. It is preferred, howev

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