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Projection
Applied Product mean all products including projection
functions, from simple projectors to projection TVs, and
projection game consoless. Projection started from
the desire to watch things on an enlarged screen. The
basic structures of projectors using either LCD or DLP
technology, which are the industry standards, are described
below
First, a light source
to enable projection is required. For light sources,
a UHP (Ultra High Pressure) mercury lamp is mainly used,
and emitted lights is projected onto image viewing devices
such as LCD panels and DLP panels (mainly below 1”) through
some optical parts. This part is called an illumination
meter. The light illuminated to imaging devices is transmitted
through or reflected by imaging devices and delivers the
image formed on the imaging devices to one spot where
magnification of the image is required. This part is called
a projection part, and consists of a few projection lens.
At this time, the circuit unit performs the role of receiving
the image signal, then driving imaging devices matches
them with the image signal, thus enabling the image to
be implemented on the imaging devices as well as being
able to make the lamp emit light.
The imaging device itself consists of monos, and its various
methods are distinguished in terms of the implementing
method of color. As the methods of implementing colors,
first, there is a method to separate white lights emitted
from the lamp by using various filters simultaneously
and create images by using three pieces of image devices.
Then colors are mixed by using optical lens, etc. simultaneously.
Second, there is a method to separate white lights into
red, green, and blue in sequence of time by using a filter
such as a color wheel and then to mix colors in sequence
by using a piece of the imaging device. In the latter
case, since red, green, blue should be represented by
dividing the time, high-speed data processing capabilities
of the imaging device itself are required.
Recently, the products to which LEDs rather than UHP mercury
lamps were applied are provided to the market. In case
of using products with LED. They drive R, G, B in sequence.
Therefore, in cases where the imaging device for which
the time-division method can be used, color separation
is not required in illumination meters, so the optical
system is efficiently configured. As for LED, its color
purity is better compared to that of a UHP lamp, and its
life span is long, so it is not necessary to replace the
lamp regularly as is performed for conventional projectors.
Also, its noise is somewhat less. However, although the
efficiency of LED brightness is rapidly being improved,
the brightness itself is still not at the level of UHP
lamps yet.
When using a laser regarded as suitable for ultra-miniaturized
Applied Products and portable Applied Products, R,G, B
are driven in sequence just like the LED case and since
the power consumption level of the laser is lower than
that of LED, this laser is advantageous for application
miniaturization, but with a higher cost higher than LEDs,
it is spotlighted as a next generation solution.
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The 3-LCD technology was first developed
by the Seiko-Epson Company of Japan, is used in present projectors,
and will most likely continue to perform a core role of projection
technologies in the future. Only three companies (Seiko-Epson, Sony, and ILJIN Display Co., Ltd.) in the world can manufacture this product.
The micro LCD (its size is mainly below 1”) is used in 3-LCD
systems and is also known as HTPS LCD, and since it is processed
at a high temperature of more than 1000 ˚C, it can be used in
the projection environments requiring high light-resistance
and high heat-resistance. Despite its small size, it usually
has the resolution of LCD level for notebooks (XGA: 1024X768
pixel).
In Micro LCD, when voltage is applied to each pixel, a liquid
crystal responds so that light delivered from light sources
can be transmitted or blocked, due to which the gray image is
represented. This process is represented as ‘driving’, and ILJIN Display Co., Ltd. can easily prevent shadow images and crosswalk phenomenon due to its unique driving method differentiated from the method of other competitors. ILJIN Display Co., Ltd. also can support tailor-made gamma correction and color correction, etc.
The 3-LCD system disassembles light emitted from the lamp into
three colors (three primary colors of light) such as R (red),
G (green), and B (Blue), allots an LCD per each color and then
makes each light transmitted to represent forms and movements.
Since light continues to be transmitted through all panels,
its color representing capability is excellent.
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The optical system of projection
modules should be ultra-miniaturized so that a projection function
can be embedded in mobile devices such as a mobile phone. For
this ultra-miniaturization, the transmission type is more favorable
than the reflection type. Also, the system, which can implement
colors by using a single piece of panel rather than using many
pieces of panels, is necessary. Until now, as a method to implement
colors by using a piece of transmission type, color filters
has been used. With this method, the resolution decreases to
one third, bright ness is very low and there is no productivity
for color filter processing itself, so this method is not suitable
for projection.
Therefore, the method to implement colors by using a piece of
panel is required. Dividing each R,G, B color according to the
time and drive of these colors is suitable. Also, in case a
light source is separated into R, G, and B from the outset,
the separating process of colors can be deleted, so this method
is highly suited for ultra-miniature optical systems.
However, the field sequential color driving by using one of
the 3-LCD panels is not available because the speed at which
liquid crystal responses and video data get addressed to each
pixel cannot catch up with the speed for field sequential color
driving.
The 1-LCD technology of ILJIN Display Co., Ltd. enables
this video data addressing time to be 1000 times faster than
3-LCD, and the response time of the liquid crystal to be 10
times faster. Therefore, it is truly a field sequential color
implementation method.
The merits of 1-LCD technologies are to enable the production
of an ultra-miniature/light-weight projection module since this
technology uses a piece of transmission type panel, to be robust
against the impact compared to DLP according to the nature of
the technology, and to represent gray scale softly.
When a 1-LCD panel is applied, the panel price decreases and
the optical system is simplified and miniaturized, so the cost
of the whole system decreases. Accordingly, Applied Products
such as ultra-low cost distribution type projector, pocket projector
with LED applied, or mobile phone projection module (integrated/
stand-alone) requiring ultra-miniaturization can be manufactured.
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In the projection
market, 3-LCD and DLP technologies are rivals, but in
an area where brightness level is low, generally DLP is dominant,
and in areas where brightness level is high, generally LCD is
dominant. The 3-LCD technology started by Seiko-Epson Company,
is currently manufactured only by Epson, Sony, and ILJIN Display
Co., Ltd. The industrial infrastructure is mainly centered in
Japan. There is too much restriction in terms of price and size
to be used for ultra-miniature Applied Products.
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DLP is a
method developed by TI (Texas Instrument) Company of the U.S.,
and it operates with a mechanism that magnifies and transmits
image signals, which were entered from the outside, by using
DMD (Digital Micro mirror Device) semiconductors on which hundreds
of thousands of micro driven mirrors are integrated.Since
hundreds of thousands of mirrors, which are switching over 5
hundred thousands times a second, control collected lights by
the digital method, a process, which converts gamma signal lamps
just like an LCD type of an analogue method, or in which image-processed
digital signals go through the D/A converter, is not necessary.
There is too much restriction in terms of price, size (thickness),
and impact-resistance to be used for ultra-miniature Applied
Products.
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LCOS is a display made by replacing bottom glasses with silicon wafers in the conventional liquid crystal display (LCD) element and forming the circuit on them.
The driving principle is similar to the 3-LCD case, but since
the circuit unit is placed on the bottom, the part on which
light is reflected (aperture) is enlarged. Therefore, it is
known that higher resolution and transmission rates can be acquired.
There is too much restriction in terms of size and mass-manufacture
issues to be used for ultra-miniature Applied Products.
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| < Technology Comparison
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