Optics: image projectors – Miscellaneous
Reexamination Certificate
2000-06-09
2003-03-18
Dowling, William (Department: 2851)
Optics: image projectors
Miscellaneous
C353S121000, C353S098000, C345S215000
Reexamination Certificate
active
06533423
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an overhead projector (OHP).
2. Description of the Related Art
If a lecturer speaks while using visual effects, such as writing letters on the blackboard or giving an explanation using an OHP, the following advantages are obtained:
making a statement clearly understandable by enumerating key words;
increasing credibility of a statement by presentation of data or the like; and
enabling the lecturer to depict a color and structure by means of a photograph, drawing and the like, which can not be expressed by words. There are various methods of providing these visual effects.
Methods of providing visual effects are classified into a direct method and an indirect method.
The direct method is such a method that a listener directly looks at supplementary data. For example, there is a method in which a lecturer brings an actual object to demonstrate in front of a listener, or a method in which a lecturer has a listener directly look at an actual object or its model to understand the three-dimensional shape. A method in which a poster is put or actual writing is made on the blackboard etc. is also included in this direct method.
On the other hand, the indirect method is such a method that a listener indirectly look at supplementary data, and includes a projection type in which a listener looks at an image projected on a screen, and a direct view type in which a listener directly looks at an image projected on a display.
The direct view type uses a liquid crystal display, a plasma display, a light emitting diode, or the like. Since a large screen display is very expensive and requires a considerably wide storage space when it is not used, a number of medium-sized displays are often set in the case where a direct view type display device is used in a large lecture place. Alternatively, a direct view type display device is often used in a small lecture meeting.
The projection type uses a liquid crystal projector, a slide projector, or an overhead projector.
The liquid crystal projector is a projection type display device using a transmission type liquid crystal panel, and is a device for projecting an image displayed on the liquid crystal panel on a screen. Projected light emitted from a lamp and having transmitted through the liquid crystal panel is enlarged by an optical system and is projected on the screen.
The projected light means light travelling until an image to be projected on a screen reaches the screen. That is, light in the space from a liquid crystal panel through which the light transmits to a screen which the light reaches, is defined as the projected light.
The liquid crystal projector is designed such that a personal computer can be connected thereto, and an image displayed on a display of the personal computer is directly displayed on a liquid crystal panel in the liquid crystal projector, and the image is projected on a screen.
Thus, anything which can be displayed on a personal computer can be projected on the screen. For example, it is possible to move a mouse (in this case, it also functions as a pointer) and to write letters, and further, it becomes possible to project an animation and to explain by using realistic pictures. In addition, since pictures can be easily enlarged or reduced on a personal computer, it is possible to vigorously put stress on what a lecturer wants to be seen, an also in this point, it effectively functions as a means for assisting a lecture.
When the liquid crystal panel of the liquid crystal projector is made high pixels, vivid pictures can be presented, and further, by adopting digital blur correction or an optical system, a uniform bright high picture quality is realized. As a result, even if a projection distance is extended, a clear image can be obtained. Thus, the liquid crystal projector is effective even for a large meeting place of a scale of several hundred persons.
The liquid crystal projector is designed such that it is compact and can be easily carried, and when it is used in combination with a notebook-sized personal computer, it does not require a wide space and can be used even in a small meeting place of a scale of several persons to ten and several persons.
The slide projector uses a method in which an image taken on a film by a camera is made a slide and the slide is projected on a screen by a lamp similarly to the foregoing liquid crystal projector.
Since an image is projected on a screen by the same function as enlargement of a photograph, a clear image with high resolution can be projected. Moreover, since the slide projector uses a powerful lamp, a projection distance is long. Thus, it can be used for a large meeting place of a scale of one thousand persons. Moreover, if the slide projector is set in advance, different images can be sequentially supplied by only a switching operation.
The overhead projector (OHP) is a device in which letters or figures are written by an oily pen or are printed on an OHP film made of transparent resin to prepare data for projection, and the data are projected on a screen by a lamp.
The OHP has a feature that although projection is made on an almost vertical screen, an OHP film is placed horizontally. Thus, it is necessary to change the travelling direction of projected light. A mirror is used as a means for changing the travelling direction of projected light. By causing the projected light to be reflected to change its travelling direction, it is possible to project an image on an almost vertical screen.
In the case of a transmission type OHP, as shown in
FIG. 6
, projected light emitted from a lamp
601
and having transmitted through an OHP film
105
is enlarged by an optical system
108
set above the OHP film, is reflected by a mirror
602
set above the optical system, and is projected on a screen
106
.
The optical system is constituted by one or plural lenses, and serves to enlarge or reduce an image, and to adjust focus.
In the foregoing device, although the enlargement of projected light is made prior to the reflection by the mirror, there is also a device for making enlargement after reflection by a mirror. Further, there is also a device in which optical systems are set before and behind a mirror.
There is a plane lens
603
under a stage
104
on which a transparent film is put. Light is emitted from the lamp
601
set below the plane lens, is refracted by the plane lens, and transmits through the transparent film
105
to become projected light. Since this projected light is refracted by the plane lens, it is designed such that the projected light goes in the optical system
108
smaller area than the transparent film.
Focusing can be made through a distance
604
between the plane lens
603
and the optical system
108
, or through a distance
605
between the optical system
108
and the screen
106
. Concretely, focusing is made by moving the optical system
108
or moving a head portion
107
of the QHP.
Since the structure of the OHP is simple, it has the following advantages: it is inexpensive; it can be compactly folded so that it is convenient to carry; preparation of data is easy and there is little trouble during a lecture. Accordingly, the OHP is naturally used in a workplace or a meeting place, and is also often used among students. That is, the OHP is a most popular display device for a lecture at present. There are mainly methods (1) to (3) described below as methods of recording the content of a lecture.
(1) Documents such as a paper and drawing
A method in which one looks at documents such as a copy of supplemental data for an OHP or the like used in the lecture, a paper describing the content of the lecture summarized in shorthand, and an outline of the content of the lecture summarized by a lecturer himself or herself.
(2) Voice
A method in which the content spoken by a lecturer in the lecture is recorded by a tape recorder or an MD disc, and is later reproduced to be heard.
(3) Picture
A method in which pictures are recorded by a video camera, and both voices and
Dowling William
Robinson Eric J.
Robinson Intellectual Property Law Office P.C.
Semiconductor Energy Laboratory Co,. Ltd.
LandOfFree
Projection type display device with image pickup function... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Projection type display device with image pickup function..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Projection type display device with image pickup function... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3060045