Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-06-21
2004-09-21
Flynn, Nathan J. (Department: 2826)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06795140
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a so-called field sequential format image display device.
2. Related Background Art
(1) Conventionally, image display devices for displaying all sorts of information are being used in various fields, as is explained below.
In recent years, there have been more and more situations in which large-screen display devices are used for enjoying movie, television images and home video images in the home, and for using various picture image sources, such as for presentations and television conferences, in the office.
Furthermore, in contrast to the case of sequentially scanning multiple display value picture elements inside the screen to display an image as in the case of conventional CRT and liquid crystal, there exists a display device using a binary display picture element and performing time divisional display based on pulse width modulation (PWM) per each indicated value in order to realize a multiple gradation display. Examples of display devices for performing such time division display include plasma display; ferroelectric liquid crystal (FLC); rear-type projection television using binary-displayable spatial modulation elements (image display elements) being represented by MEMS (micro-electro-mechanical systems)-type elements such as those of the DMD devices of Texas Instruments (TI); and projection-type projectors.
Furthermore, it is desirable to realize a display portion of which the construction itself is concise, and thus inexpensive and light, so as to provide a product that may be easily purchased by a consumer.
(2) In recent years, colorization of the display is desired. One method for this is a so-called field sequential method. Hereinafter, explanation is made of this method.
In the case of a projection-type display device such as a projector, one layer of the spatial modulation element is used to display the image in each color sequentially, and synthesis thereof is performed by the vision faculties of the viewer. Thus, for realizing a single display, the single-plate sequential color-switching-format display device not only requires only one third of the cost of the conventional three-plate format for the spatial modulation elements and peripheral circuitry, but also, the optical system and the electrical circuitry system, for example, are simplified. This is one method for realizing an inexpensive and light display portion.
Methods of sequentially switching the color include a format such that a color filter is made out of a high-speed responding liquid crystal and switching is performed therewith, and a format such that a disc-shaped color filter is made to rotate and switching is performed therewith, for example.
(3) Explanation is made of an image display device using this field sequential format, making reference to an example of a conventional construction in FIG.
8
.
A conventional image display device
200
, as shown in
FIG. 8
, is equipped with an image display element
2
for modulating incident light and displaying a black-and-white image, and is constructed so that light is irradiated to a display element
2
from an illumination device
203
. This illumination device
203
is constructed of a metal halide lamp
30
for irradiating white light; one disc-shaped color filter plate
231
arranged between the lamp
231
and an image display element
2
; and a filter rotating unit
233
for rotating the color filter plate
231
. Further, by rotating the color filter plate
231
at a fixed speed by means of the filter rotating unit
233
, a construction is realized such that light of each color is sequentially radiated to the display element
2
. Here, the term “black-and-white image” is used in contrast to “color image”, and does not refer to binary gradation. For example, the image display element
2
of the present embodiment is a binary display device, but multiple-gradation display may be realized by performing time division operations.
The illumination device
203
is constructed as described above. Thus, the images displayed to the image display element
2
are sequentially switched in synchronization with the sequential radiation of each color of light. This produces the result that the image is displayed to the screen
4
in each color. The color images in multiple colors are visually mixed, and thus recognized as a full color image.
Note that, the color filter plate
231
, as shown in detail in
FIG. 9
, is divided into the color areas
231
R,
231
G and
231
B, red, green and blue, respectively. Reference numeral
231
a
indicates the rotational center of the color filter plate
231
.
(4) Hereinafter, explanation is made of a detailed construction of the image display device, for reference.
Reference numeral
7
is an image signal input unit. Reference numeral
8
is a signal processing unit for adjusting image qualities of an inputted picture image signal such as brightness, color characteristics and gamma characteristics, performing image signal processing of converting the inputted picture image to a time division signal based on a pulse width modulation suitable for driving the display element, and generating, for example, a pulse for driving the display element and a motor control signal. Reference numeral
8
a
is a data bus for transmitting the time division signal to the display element, and reference numeral
8
b
is a control line for transmitting the drive pulse to the display element.
Reference numeral
2
is the ferroelectric liquid crystal (FLC) or the binary display image display element represented by the MEMS (micro-electro-mechanical systems)-type element such as the DVD device from Texas Instruments (TI), and is a reelection-type display element for reflecting light.
Reference numeral
35
is a ballast power source for lighting up the metal halide lamp
30
. Reference numeral
5
is an optical system for projection for projecting reflected light from the image display element
2
to a screen
4
. Lenses
37
and
38
are arranged between the color filter member
231
and the lamp
30
, and between the color filter member
231
and the image display element
2
, respectively.
Reference numeral
360
is a detection sensor for detecting the rotational position of the color filter member
231
. By means of this detection sensor
360
, the rotational phase of the color filter member
360
is communicated to a unit of controlling filter motor within a signal processing unit
8
. In order to achieve synchronization of the signal for driving the display element with the rotation phase of the color filter, the unit of controlling filter motor controls the motor control signal by means of a PLL circuit or the like and drives the rotating filter driving portion
233
via a signal line
62
.
Next, explanation is made with reference to
FIG. 10
of a construction of the above-mentioned signal processing unit
8
. Here,
FIG. 10
is a block diagram showing a detailed construction of the signal processing unit
8
.
The image signal input unit
7
has: an image signal input terminal
71
; an input terminal
72
for input of a horizontal synchronization signal for the input signal (IHD); an input terminal
73
for input of a vertical synchronization signal for the input signal (IVD); and an input terminal
74
for input of a clock of the input signal (ICLK).
In the diagram, reference numerals
711
,
712
,
713
and
714
indicate a data bus for the image signal. Reference numeral
721
indicates a signal line of the horizontal synchronization signal for the input signal (IHD), reference numeral
732
indicates a signal line of the vertical synchronization signal for the input signal (IVD), and reference numeral
741
indicates a signal line of the input signal clock (ICLK).
Reference numeral
80
is an image input unit being a receiving unit for receiving an image signal, such as a decorder for decoding, upon receiving a signal in TMDS format that is an image transmission format adopted in DVI (Digital Visual Interface) standard standardized by a standardiza
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Flynn Nathan J.
Sefer Ahmed N.
LandOfFree
Image display device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image display device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image display device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3200890