Optical: systems and elements – Polarization without modulation – Polarization by reflection or refraction
Reexamination Certificate
2001-03-30
2004-02-24
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Polarization without modulation
Polarization by reflection or refraction
C359S494010, C362S019000
Reexamination Certificate
active
06697197
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and system for producing (i) a modulated beam of electromagnetic energy, (ii) a modulated beam of light or ultraviolet light, (iii) a visual image for display, (iv) one or more collinear beams of electromagnetic energy, (v) one or more collinear beams of ultraviolet light, (vi) a modulated beam of visible light in which the brightness of the image increases as the distance from the projector lens to the screen increases up to a distance of approximately 10 feet, (vii) a modulated beam of light for projection of video images, (viii) a collinear beam of electromagnetic energy having two constituent parts, (ix) a collinear beam of light (or ultraviolet light) having two constituent parts, (x) one or more collinear beams of electromagnetic energy, (xi) one or more collinear beams of light or ultraviolet light, (xii) a substantially collimated beam of electromagnetic energy having substantially the same selected predetermined orientation of a chosen component of electromagnetic wave field vectors and a substantially uniform flux intensity substantially across the beam of electromagnetic energy for use in the above method and systems, (xiii) a substantially collimated beam of light (or ultraviolet light) having substantially the same selected predetermined orientation of a chosen component of electric field vectors and a substantially uniform flux intensity substantially across the beam of light for use in the above method and systems, and (xiv) displaying an image in either two dimensions (2D) or three dimensions (3D). This invention also relates to projection type color display devices and projection apparatuses.
BACKGROUND OF THE INVENTION
A disturbance (change in position or state of individual particles) in the fabric of space-time causes a sphere of influence. Stated in a simplistic manner, the action of one particle influences the actions of the others near it. This sphere of influence is referred to as a “field”, and this field is designated as either electric or magnetic (after the way it influences other particles). The direction of travel of the particle is called the direction of propagation. The propagation of the particle, the sphere of influence, and the way it influences other particles is called an electromagnetic wave, and is shown in FIG.
1
.
As shown in
FIG. 1
, the electric and magnetic fields are orthogonal (at right angles) to each other and the direction of propagation. These fields can be mathematically expressed as a vector quantity (indicating the direction of influence along with strength, i.e., magnitude, of influence) at a specific point or in a given region in space. Thus,
FIG. 1A
is the electromagnetic wave in
FIG. 1
, but with the view of looking down the axis of propagation, that is, down the axis of FIG.
1
.
FIG. 1A
shows some possible various electric field vectors that could exist, although it should be understood that any and all possible vectors can exist around the circle, each having different magnitudes.
Vectors can be resolved into constituent components along two axes. This is done for convenience sake and for generating a frame of reference that we, as humans, can understand. By referring to
FIG. 1B
, it is shown that the electric field vector E, can be resolved into two constituent components, E(y) and E(x). These quantities, then, describe the orientation and the magnitude of the electric field vector along two axes, the x and y, although other axes or systems could be chosen. The same applies to magnetic fields, except that the X and Z axes would be involved.
The way the electric and magnetic fields vary with time in intensity and direction of propagation have been determined by several notable mathematicians and physicists, culminating in a group of basis equations by James Maxwell. These equations, simply applied, state that a field vector can be of one of several different states, that is: 1) the field vector varies randomly over a period of time, or 2) the field vector can change directions in a circular manner, or 3) the field vector can change directions in a elliptical manner, or 4) the field vector can remain constant in magnitude and direction, hence, the field vector lies in one plane, and is referred to as planar.
This orientation of a field vector and the way it changes with time is called the state of polarization.
Electromagnetic waves can be resolved into separate electromagnetic waves with predetermined orientations of a field vector. The electromagnetic waves with a predetermined orientation of a field vector can then be directed through materials, such as a liquid crystal device, that is capable of changing (or altering) their orientation of the field vector upon application of an outside stimulus, as is demonstrated in FIG.
7
. These devices are noted as programmable electromagnetic wave field orientation rotating devices (PEMFVORD).
An electromagnetic wave can be characterized by its frequency or wavelength. The electromagnetic spectrum (range) extends from zero, the short wavelength limit, to infinity, the long wavelength limit. Different wavelength areas have been given names over the years, such as cosmic rays, alpha rays, beta rays, gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, TV and FM radio, short wave, AM, maritime communications, etc. All of these are just short hand expressions of stating a certain range of frequencies for electromagnetic waves.
Different areas of the spectrum interact with electromagnetic influences upon them in various proportions, with the low end being more influenced by magnetic fields, and the high end being influenced by electric fields. Thus to contain a nuclear reaction, a magnetic field is used, while controlling light an electric field is used.
FIG. 2
illustrates a schematic cross section of an LCD cell. The LCD cell
100
includes a liquid crystal material
101
that is contained between two transparent plates
103
,
104
. Spacers
105
,
106
are used to separate the transparent plates
103
,
104
. Sealing elements
107
,
108
seal the liquid crystal material
101
between the transparent plates
103
,
104
. Conductive coatings
109
,
110
on the transparent plates
103
,
104
conduct the appropriate electrical signals to the liquid crystal material
101
.
A type of liquid crystal material
101
used in most LCD cells for optical display systems is referred to as “twisted nematic.” In general, with a twisted nematic LCD cell, the molecules of an LCD cell are rotated in the absence of a field through a 90° angle between the upper
103
and lower
104
transparent plates. When a field is applied, the molecules are untwisted and line up in the direction of the applied field. The change in alignment of the molecules causes a change in the birefringence of the cell. In the homogeneous ordering, the birefringence of the cell changes from large to small whereas the opposite occurs in the homeotropic case. The change in birefringence causes a change in the orientation of the electric field vector for the light being passed through the LCD. The amount of the rotation in the molecules for an individual LCD cell
100
will determine how much change in polarization (orientation of the electric field vector) of the light occurs for that pixel. The light beam is then passed through another component of the system (i.e., polarizer analyzer) and is resolved into different beams of light by the orientation of their electric field vectors, with the light that has a selected predetermined component of the electric field vector passing through to finally strike the screen used for the display.
A twisted nematic LCD cell requires the light incident at the LCD cell
100
to be polarized. The polarized light for a typical projector is generally derived from a randomly polarized light source that is collimated and then filtered by a plastic polarizer to provide a linear polarized beam. Linear polarized beams are conventionally referred to as being S-polarized and P-polarized with the P-polarized beam d
Au Optronics Corporation
Fineman Lee
Law Office of Roxana H. Yang
Robinson Mark A.
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