Optics: image projectors – Reflector
Reexamination Certificate
2001-03-21
2002-11-05
Adams, Russell (Department: 2851)
Optics: image projectors
Reflector
C353S034000, C353S035000, C349S006000
Reexamination Certificate
active
06474819
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to projection displays and particularly to combining an electronic and overhead display in a single unit.
BACKGROUND OF THE INVENTION
For many years overhead projectors have been popular as a means of projecting prepared transparencies or free-hand transparencies that are drawn in real-time, on to a display screen for viewing by a group (one or more) of viewers. More recently electronic displays, which are connected to various electronic data sources, have been used to project images normally seen on a computer screen on to a larger display screen for viewing by a group of viewers. Today, it is often necessary to equip conference or meeting rooms with both an overhead projector and an electronic display projector in order to accommodate uninterrupted presentations. This tends to be both expensive and somewhat awkward in switching between the projectors.
FIGS. 1
a
and
1
b
are diagrams showing a [top and] side view and a top view, respectively, for a typical overhead projector used in such applications. These projectors are typically packaged in two parts; e.g., a main projector housing
10
and a remote projection head
11
. The main housing
10
consists of a bright, white light source
100
(lamp) along with its power supply (not shown), a rather large turning mirror
101
, and a Fresnel lens
102
located just below a top glass media surface
103
. The projection head
11
consists of a condensing lens
110
, a smaller turning mirror
111
, and a projection lens
112
.
In operation, the operator (presenter) places a transparency on top of the glass media surface
103
just above the Fresnel lens
102
. Light from the light source
100
is reflected and bent upward through the Fresnel lens
102
, through the glass cover
103
supporting the transparency, and into the projection head
11
. The light is modulated by a pattern on the transparency to provide an image with the dark areas of the transparency being black and the open areas of the transparency being white. In the projection head
11
, the image is focused on to a smaller turning mirror
111
by means of a condensing lens
110
. Light is then reflected off the turning mirror
111
, through a projection lens
112
, and on to an appropriate display screen
12
, usually a white surface. The small turning mirror
111
can be tilted up and down to properly position the image on the screen and the projection lens
112
can be manually adjusted to properly focus the image on the screen. In the top view, the relative sizes of the projector's large turning mirror
101
, the transparency
102
, and the projection head's smaller turning mirror
111
are shown.
Electronic projectors have become quite popular in recent years due to their small size, lightweight, and high performance. These projectors are electronically driven with media content that is used to modulate the light and present either a color or black-and-white image on the display screen. The projectors come in different configurations, but usually use a spatial light modulator (SLM), such as a reflective digital micromirror device (DMD™) or liquid crystal device (LCD), to modulate the data. The projectors can be very small and lightweight, built around a single SLM and present a high-resolution, bright image with brilliant color representation. Electronic displays having two or three SLMs are also used for applications that require brighter projectors, such as for use in large conference halls.
FIG. 2
is block diagram for one configuration of a single-SLM electronic display projector. In this example, the projector is comprised of a white light source
200
, which consists of a lamp and collector for gathering the light from the lamp and focusing it to a small spot at a point along the generated light beam. A rotating color filter wheel
201
is inserted at the focused spot of light in the light beam. A motor turns the wheel in synchronization with the electronic data being presented. The color wheel
201
is made up of red, green, and blue (primary colors) segments and transforms the clear light into sequential red, blue, and green light beams. In some cases, an optional white segment is added to the color wheel to help boost the overall brightness of the projector. In this configuration, light from the color wheel
201
is then passed through a light-integrating rod
202
, through a condensing lens
203
, and into a total internal reflective (TIR) prism
204
. Inside this TIR prism, the light is reflected and directed on to the surface of a SLM
205
where it is modulated according to the electronic data content. Modulated light is then reflected off the surface of the SLM
205
, back through the TIR prism
204
, through a projection lens
206
, and on to a display screen
207
. Other optical configurations for such projectors do not necessarily utilize a TIR prism and/or integrating rod.
Together, these two projector types satisfy most presentation needs. However, what is needed is a flexible projection system that offers both of these projection capabilities in a single, reasonably priced package. The projector embodiments of the present invention meet this need by providing a single high-performance, comprehensive solution that addresses both the overhead projection display needs, as well as electronic display needs. The invention further provides a new function of capturing drawn transparencies from the overhead function and integrating (overlaying) these with the electronic content in terms of both an optical projected image and stored data.
SUMMARY OF THE INVENTION
The present invention discloses three embodiments of a combined overhead projector and electronic display projector system. The combined projector of this invention serves three major purposes. First, the overhead projector serves to display transparencies. Second, the electronic display device projects electronic data from several different types of electronic input sources, including NTSC and HDTV television, VGA (computer), S-video, etc. Third, both the overhead functionality and electronic display functionality can be used simultaneously to combine the data from both projectors. For example, while an electronic image is being displayed, the user can simultaneously draw in real-time a transparency so both images are superimposed on the display screen. In this mode, a camera mounted to the remote overhead projection head can be used to capture the drawn or superimposed image. Once captured by the camera, the new superimposed image can be electronically stored for future use.
Historically, overhead projectors and electronic projection displays have required the purchase of two completely separate products to address the two applications. In addition, before this invention it was difficult to simultaneously provide the functions of both the overhead projector display and the electronic projection display.
This invention provides a single comprehensive solution, which addresses both the overhead projection display needs as well as electronic projection display needs. The invention further provides a new function of integrating both drawn transparencies and electronic content in terms of both an optical projected display and electronic stored data.
REFERENCES:
patent: 5159363 (1992-10-01), Brauning
patent: 5400095 (1995-03-01), Minich et al.
patent: 5477284 (1995-12-01), Taylor et al.
patent: 5593221 (1997-01-01), Evanicky et al.
patent: 6181388 (2001-01-01), Nomura
patent: 2559923 (1985-08-01), None
Davis Michael T.
Moizio Frank J.
Yoder Lars A.
Adams Russell
Brady III Wade James
Brill Charles A.
Nguyen Michelle
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