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| United States Patent | 5724062 |
| Link to this page | http://www.wikipatents.com/5724062.html |
| Inventor(s) | Hunter; C. Eric (Chapel Hill, NC) |
| Abstract | A high resolution, high brightness, full color display is provided having a
liquid crystal pixel selectably addressable during a predetermined time
period, a set of at least one red, one green, and one blue color light
emitting diodes positioned adjacent the liquid crystal pixel for emitting
light through the liquid crystal pixel, and means connected to the liquid
crystal pixel for addressing the liquid crystal pixel a plurality of times
during the predetermined time period for each color so as to provide
persistence when changes in color are perceived by the human eye. A method
of producing a high resolution, full color display is also provided by
lighting a set of one red, one green, and one blue light emitting diodes
by lighting the respective colored light sources for a predetermined time
period for each color and shuttering the set of light sources with a
liquid crystal pixel for at least a portion of the predetermined time
period to thereby emit light from the shuttered pixel for a selected time
period so as to provide persistence when changes in color are perceived by
the human eye. |
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Title Information  |
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Drawing from US Patent 5724062 |
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High resolution, high brightness light emitting diode display and method
and producing the same |
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| Publication Date |
March 3, 1998 |
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| Filing Date |
September 21, 1994 |
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| Parent Case |
RELATED APPLICATION
This application is a continuation-in-part of copending U.S. patent
application Ser. No. 07/926,035 filed on Aug. 5, 1992, U.S. Pat. No.
5,359,345. |
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Title Information  |
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References  |
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| *references marked with an asterisk below are user-added references |
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U.S. References |
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| | Reference | Relevancy | Comments | Reference | Relevancy | Comments | 5394167 Migny 345/690 Feb,1995 |      Your vote accepted [0 after 0 votes] | | 5359345 Hunter 345/102 Oct,1994 |      Your vote accepted [0 after 0 votes] | | 5307359 Sarraf 372/21 Apr,1994 |      Your vote accepted [0 after 0 votes] | | 5306662 Nakamura 438/509 Apr,1994 |      Your vote accepted [0 after 0 votes] | | 5305464 Frett 725/15 Apr,1994 |      Your vote accepted [0 after 0 votes] | | 5302839 Kaise 257/101 Apr,1994 |      Your vote accepted [0 after 0 votes] | | 5290393 Nakamura
Mar,1994 |      Your vote accepted [0 after 0 votes] | | 5273933 Hatano 117/89 Dec,1993 |      Your vote accepted [0 after 0 votes] | | 5247533 Okazaki 372/45.01 Sep,1993 |      Your vote accepted [0 after 0 votes] | | 5243204 Suzuki 257/77 Sep,1993 |      Your vote accepted [0 after 0 votes] | | 5187547 Niina 257/77 Feb,1993 |      Your vote accepted [0 after 0 votes] | | 5103328 Numao 349/74 Apr,1992 |      Your vote accepted [0 after 0 votes] | | 5093652 Bull 345/592 Mar,1992 |      Your vote accepted [0 after 0 votes] | | 5087576 Edmond
Feb,1992 |      Your vote accepted [0 after 0 votes] | | 5063421 Suzuki
Nov,1991 |      Your vote accepted [0 after 0 votes] | | 5011549 Kong 148/33.1 Apr,1991 |      Your vote accepted [0 after 0 votes] | | 4992704 Stinson 315/312 Feb,1991 |      Your vote accepted [0 after 0 votes] | | 4978952 Irwin 345/102 Dec,1990 |      Your vote accepted [0 after 0 votes] | | 4929061 Tominaga 349/70 May,1990 |      Your vote accepted [0 after 0 votes] | | 4924215 Nelson 345/88 May,1990 |      Your vote accepted [0 after 0 votes] | | 4918497 Edmond 257/77 Apr,1990 |      Your vote accepted [0 after 0 votes] | | 4917465 Conner 349/5 Apr,1990 |      Your vote accepted [0 after 0 votes] | | 4912064 Kong 438/507 Mar,1990 |      Your vote accepted [0 after 0 votes] | | 4907862 Suntola 349/61 Mar,1990 |      Your vote accepted [0 after 0 votes] | | 4870484 Sonehara 348/791 Sep,1989 |      Your vote accepted [0 after 0 votes] | | 4799050 Prince 349/71 Jan,1989 |      Your vote accepted [0 after 0 votes] | | 4744640 Phillips 359/254 May,1988 |      Your vote accepted [0 after 0 votes] | | 4716403 Morozumi 345/88 Dec,1987 |      Your vote accepted [0 after 0 votes] | | 4712878 Taniguchi 349/31 Dec,1987 |      Your vote accepted [0 after 0 votes] | | 4581608 Aftergut 345/88 Apr,1986 |      Your vote accepted [0 after 0 votes] | | 4491863 Kurahashi 348/799 Jan,1985 |      Your vote accepted [0 after 0 votes] | | 4410887 Stolov 345/50 Oct,1983 |      Your vote accepted [0 after 0 votes] | | 4368963 Stolov 353/31 Jan,1983 |      Your vote accepted [0 after 0 votes] | | 4180813 Yoneda 345/100 Dec,1979 |      Your vote accepted [0 after 0 votes] | | 3776615 Tsukamoto 345/87 Dec,1973 |      Your vote accepted [0 after 0 votes] | | 3569614 Hanlon 435/202 Mar,1971 |      Your vote accepted [0 after 0 votes] | | 5027168 Edmond 257/103 Dec,1969 |      Your vote accepted [0 after 0 votes] | | | | | |
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| Market Size |
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Estimate the gross annual revenues of the relevant market
sector:
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| Reasonable Royalty |
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What percentage of gross sales should the inventor or assignee be paid?
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Public's "Guesstimation" of Royalty Value
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| Market Size | N/A | [No votes] | | x | Market Share | N/A | [No votes] | | x | Reasonable Royalty | N/A | [No votes] |
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Market Review  |
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Technical Review  |
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Claims  |
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That which is claimed is:
1. A high resolution, full color display, comprising:
a liquid crystal pixel selectably addressable during a predetermined time
period wherein said liquid crystal pixel comprises an array of individual
portions of a liquid crystal pixel and wherein each individual portion of
said pixel is individually addressable over the predetermined time period;
an interspersed set of at least one red, one green, and one blue color
light emitting diodes positioned adjacent said liquid crystal pixel and
adapted for emitting light through said liquid crystal pixel; and
means connected to said liquid crystal pixel for selectably addressing the
liquid crystal pixel a plurality of times during the predetermined time
period so as to provide persistence when changes in color occur.
2. A high resolution, high brightness, full color display as defined by
claim 1, wherein said liquid crystal pixel is selectably addressable for
an amount of time generally less than the amount of time that the human
eye can detect changes in colors.
3. A high resolution, high brightness, full color display as defined by
claim 1 further comprising:
means connected to safe interspersed set of LEDs for lighting said
interspersed set of LEDs by respective red, green, and blue colors for a
predetermined time period for each color.
4. A high resolution, high brightness, full color display according to
claim 1, further comprising:
means connected to said set of LEDs and said liquid crystal pixel for
synchronizing the lighting of said interspersed set of LEDs with the means
for addressing said individual liquid crystal pixel a plurality of times
during the predetermined time period.
5. A high resolution, high brightness, full color display according to
claim 1, further comprising means positioned between said LEDs and said
LCD for measuring the intensity of said LEDs during a time interval.
6. A high resolution, high brightness, full color display according to
claim 1, further comprising means positioned between said set of LEDs and
said liquid crystal pixel for diffusing the light emitted from said set of
LEDs to said liquid crystal pixel.
7. A high resolution, high brightness, full color display as defined by
claim 1, wherein said blue LED is formed of gallium nitride.
8. A high resolution, high brightness, full color display as defined by
claim 1, wherein said array of LEDs are formed in a single semiconductor
substrate.
9. A method of producing a high resolution, high brightness, full color
display that is particularly useful for a flat display, comprising the
steps of:
lighting a set of one red, one green, and one blue LEDs by lighting the
respective LEDs in the set for a predetermined time period for each LED in
which one cycle is defined by the sum of the predetermined time periods,
and in which one cycle is a time period less than that for which the
sequential lighting of the LEDs can be detected by the human eye; and
shuttering the set of LEDs with a liquid crystal pixel which comprises an
array of individual portions of a liquid crystal pixel for at least a
portion of the predetermined time periods to thereby emit light from the
shuttered pixel for a selected time period from each of the red, green,
and blue LEDs so that the light emitted from the pixel is an emission of
red, green, and blue light, each for a time period less than or up to the
predetermined time period so that the emission from the pixel during each
cycle is defined by the amount of time a light pulse from each LED is
shuttered and will normally be perceived by a human eye as a blend of the
colors emitted by the respective LEDs.
10. A method as defined by claim 9, further comprising the step of:
selectably addressing the liquid crystal pixel a plurality of address times
during each predetermined time period.
11. A method as defined by claim 10, further comprising the step of:
synchronizing the addressing of the liquid crystal pixel with the lighting
of the set of red, green, and blue LEDs.
12. A method as defined by claim 9, wherein one cycle is less than the
amount of time that the human eye can detect changes in colors.
13. A method as defined by claim 9, wherein one cycle is generally less
than 1/60th of a second.
14. A method as defined by claim 9, wherein the predetermined time period
is generally less than 1/180th of a second.
15. A method of producing a high resolution, high brightness, full color
display that is particularly useful for a flat display, comprising the
steps of:
transmitting data to the display to be represented during a predetermined
time period;
receiving the data to be represented for display during the predetermined
time period;
sequentially and cyclically lighting an interspersed set of red, green, and
blue LEDs in response to the received data by lighting the respective LEDs
in the set for a predetermined time period for each color, in which one
cycle is defined by the sum of the predetermined time periods, and in
which one cycle is a time period less than that for which the sequential
lighting of the LEDs can be detected by the human eye;
addressing individually the liquid crystal pixels in a set of liquid
crystal pixels wherein at least one of said liquid crystal pixels
comprises an array of individual portions of a liquid crystal pixel and
wherein a liquid crystal pixels in the set of liquid crystal pixels is
addressed individually a plurality of address times during each sequential
predetermined time period in response to said received data;
synchronizing the addressing of the individual liquid crystal pixels with
the sequentially and cyclically lighting of the set of red, green, and
blue LEDs; and
shuttering the set of LEDs with individual pixels in the set of liquid
crystal pixels for at least a portion of the sequential predetermined time
periods in response to said received data to thereby emit light from the
shuttered pixels for a selected time period from each of the red, green,
and blue LEDs so that the light emitted from the pixel is a sequential
emission of red, green, and blue light, each for a time period less than
or up to the predetermined time period so that the emission from the
pixels during each cycle is defined by the amount of time a light pulse
from each LED is shuttered and will normally be perceived by a human eye
as a blend of the colors emitted by the respective LEDs rather than as a
sequential appearance of those colors.
16. A method as defined by claim 15, wherein one cycle is generally less
than 1/60th of a second.
17. A method as defined by claim 15, wherein said predetermined time period
is generally less than 1/180th of a second. |
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Claims  |
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Description  |
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FIELD OF THE INVENTION
This invention generally relates to display devices and more particularly
to an array of light emitting diodes in combination with a liquid crystal
display for producing a high resolution, high brightness, full color
display.
BACKGROUND OF THE INVENTION
For many years, the cathode ray tube ("CRT") dominated the display market
for numerous applications. CRTs provided high resolution, graphics, full
color, and real-time animation. CRT displays, however, have several
associated problems such as bulkiness, high voltage requirements, high
heat generation, and sensitivity to vibration and shock.
Because of the problems associated with CRT displays, other display
technologies such as the light emitting diode ("LED"), liquid crystal
display ("LCD"), vacuum fluorescent ("VF"), plasma, and
electroluminescence have been replacing CRT displays for many
applications, especially for flat panel display applications. These
technologies have various advantages in specific applications, depending
on such factors as environmental conditions, voltage requirements, and
size.
LED displays have been used for many years and have been popular because of
their ruggedness, fast switching speeds, and wide range of sizes. These
advantages, however, were somewhat diminished by the fact that blue LEDs
were difficult to develop and were expensive. Without the blue LED, a full
color LED display was impossible.
The lack of a blue LED slowed the development and marketability of LED
display technology, especially for multi-color applications such as
personal computers, computer aided design ("CAD"), and video imaging. The
need for a blue LED encouraged the development of the inventions described
in U.S. Pat. Nos. 4,918,497 and 5,027,168 by Edmond titled "Blue Light
Emitting Diode Formed In Silicon Carbide." The silicon carbide blue LED
technology, in turn, has opened the field for the development of
multi-color LED displays.
LCDs have been popular for many applications, primarily in low power areas
such as battery-powered systems (e.g., wrist watches, portable computers)
or small size applications. LCDs, however, have suffered from several
problems over the years. LCDs, for example, are difficult to view in low
ambient light environments because they transmit rather than emit light.
In addition, LCDs have a limited viewing angle and poor contrast.
For full color displays, supertwist LCD technology has been developed to
allow a wide variety of colors and improved contrast. Supertwist
technology, for example, bends light 270 degrees instead of the 90 degrees
provided by conventional LCD technology. The supertwist color LCDs still
lack the clarity and brightness achieved by CRT displays and LED displays.
More recently, due to the problems with LED and LCD technology, LCDs have
been used in combination with LEDs to attempt to achieve better clarity
and brightness for flat panel displays over the full-color spectrum,
especially for three-dimensional, multi-color, high resolution
applications. To overcome the need for a blue LED, various filters and
other devices have been used to produce the blue color when needed. Most
of these alternative blue color techniques, however, added additional
circuitry and expense and, therefore, were still not adequate for
commercial applications.
One such method for producing a full color, flat panel display is to form a
display with three colored filters (e.g., red, green, blue) for each LCD
pixel. A mixture of the filtered light shines through the LCD pixel to
display the desired color for that particular pixel. An example of this
filter method is seen in U.S. Pat. No. 4,716,403 to Morozumi titled
"Liquid Crystal Display Device." Although this is a theoretically simple
solution, the filter system fails to allow the intensity of individual
colors of light for an individual pixel to be controlled.
Another method is to use fewer LED sources and to project or scan the light
sources over a large number of LCD pixels. As the light source is directed
to a particular pixel, it lights the pixel with the appropriate color. As
long as the entire display is covered in one-sixtieth (1/60th) of a second
or less--a rate above which the human eye generally cannot detect the
individual changes taking place--an appropriate image can be maintained.
An example of such a device may be seen in U.S. Pat. No. 4,978,952 to
Irwin titled "Flat Screen Color Video Display."
In the scanning method, as shown in U.S. Pat. No. 4,978,952 to Irwin, LEDs
are used as individual light sources, and LCDs are used as shutters that
define each pixel. The LCD pixels are opened and closed a row or column at
a time in an appropriate manner to allow the LED light source to emit
through the pixels and thereby define the overall display. The intensity
of color transmitted is varied by varying the output of the source LEDs.
One problem with the scanning method, however, is a lack of power output
which from a practical standpoint results in a lack of brightness,
clarity, and overall resolution. The fundamental difficulty is that a row
or column of LCD pixels at a time is illuminated from its source. Even if
that time period for illuminating an entire row or column of LCDs is very
short and refreshed very rapidly, the brightness is greatly affected.
Therefore, the overall power output of the display is roughly limited by
the ratio of sources to pixels in that row.
Other similar attempts at addressing this problem have been made by
transferring the color to the screen a lattice or group of pixels at a
time. An example of this may be seen in U.S. Pat. No. 5,093,652 to Bull et
al. titled "Display Device." Because this device also controls blocks of
pixels at a time, instead of individual pixels, it fails to produce the
desired high resolution needed for video imaging applications. Also, the
original patent application for this device was filed in a foreign country
on Dec. 4, 1987, prior to the develo | | |