Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2001-07-23
2004-02-03
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S291000, C359S297000
Reexamination Certificate
active
06687040
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light modulating element array which is available as an optical exposure device and a panel display device and, more particularly, to a light modulating element array operative to modulate light traveling in a light guide by electromechanically deflecting a thin-film toward the light guide.
2. Description of the Related Art
There have been various panel display devices such as liquid crystal display devices and plasma display devices on the market. Such a liquid crystal display device has the problem that the utilization efficiency of light is low due to transmission of light from a backlight source through various optical elements including a polarizing plate, transparent electrodes and a color filter. On the other hand, because such a plasma display device needs to have an interstructure for discharge per pixel, there is the problem that it is difficult fort the plasma display device to provide a high luminance and a high efficiency when high definition is required and that the plasma display device needs a high drive voltage. This rises costs of the plasma display device.
In order to solve the problem, there have been proposed panel display devices equipped with electromechanically operated light modulating elements which modulate light from a light source for making an image display. One of such panel display devices is known from, for instance, a paper entitled “Waveguide Panel Display Using Electromechanical Spatial Modulators” published in SID International Symposium Digest of Technical Papers, 1998.
Before describing the present invention in detail, reference is made to
FIGS. 14 and 15
showing the panel display device disclosed in that paper for the purpose of providing a brief background of electromechanical Light modulation that will enhance understanding of the light modulating element of the present invention.
As shown in
FIG. 14
, a panel display device
15
comprises a plurality of strip-shaped light guides
3
arranged in parallel to one another and a plurality of strip-shaped, electromechanically deflectable thin-films
11
arranged in parallel to one another and perpendicularly to the light guides
3
. These light guides
3
and electromechanically deflectable thin-films
11
are disposed between a front transparent glass plate
1
and a rear transparent glass plate
13
. The light guides are formed directly on the front transparent glass plate
1
. However, each of the electromechanically deflectable thin-films
11
is partially connected to and supported by the rear transparent substrate
13
so as to be deflectable toward the light guide
3
. An LED array
9
is optically coupled to the light guides
3
through a light guide member
7
equipped with micro-lenses
5
. The LED array
9
comprises a straight row of a plurality of LEDs, one per light guide
3
. The electromechanically deflectable thin-films
13
thus arranged are operative as optical switches.
As shown in
FIG. 15
, in operation of the panel display device
15
, when selectively applying a drive voltage to electrodes of the electromechanically deflectable thin-films
11
, the electromechanically deflectable thin-film
11
deflects and is brought close to the light guide
3
due to electrostatic force. On the other hand, the LEDs of the LED array
9
are energized with image signals in synchronisms with the application of drive voltages to the electrodes of the electromechanically deflectable thin-films
11
to emit light. The light emanating from the LED enters and travels in the light guide
3
repeating total reflection. When the light travels in the light guide
3
to a proximal contact point where the light guide
3
is contacted by the electromechanically deflectable thin-film
11
, the light is reflected by a mirror
17
in the electromechanically deflectable thin-film
11
and enters the light guide
3
at a substantially right angle. As a result, the light passes though and comes out of the light guide
3
at the proximal contact point. On the other hand, when the drive voltage is removed, the electromechanically deflectable thin-film
11
is restored to its original state and provides a gap between the light guide
3
and the electromechanically deflectable thin-film
11
, so that the light travels in the light guide
3
without coming out of the light guide
3
and entering the electromechanically deflectable thin-film
11
.
The panel display device
15
employs the electromechanically deflectable thin-film
11
that can operate quickly responding to application of drive voltage. This makes the panel display device
15
operate with high responsiveness. Further, the panel display device
15
does not employ a number of layers through which light passes like the conventional liquid crystal display panels nor have the necessity of vacuum-sealing electrode arrays like the plasma display panels. This realizes manufacturing costs of the panel display device
15
.
The conventional panel display device makes a two dimensional display by making a line display by applying drive voltage to one of the electromechanically deflectable thin-films and introducing light modulated according to image signals into the light guides in synchronism with the application of voltage to the electromechanically deflectable thin-film and shifting application of drive voltage to the electromechanically deflectable thin-films from one to another. In order for the conventional panel display device to make an animated color display in HDTV (high definition television) system which has 1080 scanning lines and a frame frequency of 60 Hz, it is essential to employ an LED array which is operative to modulate light at a high frequency less than 16 &mgr;s. For this reason, it is one of drawbacks that the conventional panel display device can not employ a fluorescent lamp that is inexpensive and efficient. In addition, the conventional panel display device has the necessity to have the same number of LEDs as the light guides. Accordingly, when making a color display in HDTV system, the number of image signals is 1920 for a mono-color line display, and hence, 5760 for a color line display. This makes an image signaling circuit complex and the LED array expensive. In addition, this results in the necessity of precise positioning technique in order to optically couple the LED array to the light guides and provides a rise in manufacturing and assembling costs of the LED array and the light guides.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a light modulating element array which does not need an array of light source elements nor has the necessity to modulate light at a high speed.
It is another object of the present invention to provide a light modulating element array simple in structure and unnecessary to use a precise positioning skill which results in a decrease in manufacturing and assembling costs of light source and the light guides.
It is still another object of the present invention to provide a panel display device equipped with a light modulating element array which is simple in structure and manufactured at low costs.
The foregoing objects are accomplished by providing a light modulating element array comprising a grid arrangement of stripe-shaped light guides, such as optical wave guides or light guide plates, for guiding light entering there so that the light travels in the light guide repeating total reflection at opposite interfaces of the light guide and strip-shaped electromechanically deflectable subsidiary thin-films disposed such as to face the light guides, respectively, at a specified regular distances from the interface of the respective light guides, and strip-shaped electromechanically deflectable main thin-films each of which extends in a direction in which the light travels in the light guide and is disposed such as to face the light guide before the subsidiary thin-film at a specified regular distance from the interface of the light guide. When the main thin-film
Epps Georgia
Fuji Photo Film Co. , Ltd.
Hasan M.
Young & Thompson
LandOfFree
Light modulating element array and method of driving the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light modulating element array and method of driving the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light modulating element array and method of driving the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3295938