Toshiba Mobile Display (TMD) has developed a 7.0-inch LTPS TFT LCD panel
as a demonstration of its integrated in-cell touch panel technology
Features capacitive multi-touch input
function integrated in the liquid crystal cell
Press Release
4/26/2011
Toshiba Mobile Display Co., Ltd.
has developed a 7.0-inch low-temperature poly-silicon (LTPS)
thin-film transistor (TFT) liquid crystal display (LCD)
for vehicle-mounted and industrial uses that enables multi-touch
input on the display screen without the need for additional
installation of a touch panel as a demonstration of its new touch panel technology.
The technology enables an integrated touch panel function by forming the display pixel
electrodes and TFT within the LCD panel using LTPS TFT technology and
creating a detecting circuit for electrostatic capacitance changes
between the electrodes and the peripheral object.
Compared to conventional LCDs with an external touch panel,
the thickness is reduced by 57 percent to approximately 1 millimeter,
the weight is reduced by 48 percent to 225 grams and the surface reflection
ratio is reduced by 10 percent. Its smaller size enables the design of more compact
products for mobile applications, reduces the impact on the environment by saving
resources and power, provides crisp and clear images with minimal reflection of
natural light even in a bright environment, and features intuitive multi-touch input.
Recently, an increasing number of smartphones, cellular phones,
in-vehicle car navigation systems, tablet-type PCs and other
equipment for mobile applications have been designed around a
capacitive-type touch panel1 integrated LCD, thereby facilitating
the rapid spread of products that feature a low-profile and reduced-weight design,
and intuitive, easy and simple touch input. TMD has developed this technology in
response to the increasing demand for in-cell touch panel2 LCDs with the touch
panel function integrated in the LCD panel for further reduction of thickness,
weight and environmental impact.
The capacitive-type touch panel is designed to form transparent electrodes
on the touch panel and detect changes in electrostatic capacitance between
the electrodes and the user’s fingers with high accuracy, thereby enabling
the screen panel to respond easily to light finger touches.
To integrate this feature in the LCD panel it is essential to
suppress possible interference with various signals in the LCD panel.
To address the problem, TMD has developed a proprietary sensor circuit,
taking advantage of LTPS TFT technology. Specifically, an amplifier circuit
is formed in the pixels to amplify the signals, which are then detected by
the sensor for output, providing a configuration to precisely transmit sensor
signals to the outside of LCD panel.
This helps achieve consistent and fast-responding touch panel operation.
This technology will be exhibited in the Toshiba
booth #1119 at SID 2011 International Symposium,
Seminar and Exhibition to be held from May 17 to May 19,
2011 in Los Angeles, Calif., USA.
Notes
1“Capacitive-type touch panel”
A touch panel detecting system which determines the location of the
input touch based on the change in electrostatic capacitance between
the user’s finger and the touch panel’s conductive layer.
As the user’s finger approaches the touch panel, electrostatic
coupling between the finger and the conductive layer changes,
allowing detection of the location of the input touch.
Existing LCD panels with a built-in touch panel have an independent touch panel
mounted on the surface layer of the LCD panel as an independent separate component.
2 “In-cell touch panel”
The “in-cell touch panel” refers
to the configuration with the touch panel function
integrated into the LCD panel.
It is commercially available in several designs,
including one which incorporates an optical sensor
to detect the finger images through an external or
an internal light source, and another which detects
electrical changes caused by pressing and deforming
the two (2) glass substrates of the LCD panel.
This newly developed product is based on TMD's
proprietary design that enables detection of changes
in electrostatic capacitance caused by a touch of the
finger without additional installation of any
light source for optical sensor or such larger
pressing forces which deflect the LCD panel.
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