Development of Sensor Device Using High-transparency Organic Piezoelectric Film
Murata Manufacturing Co., Ltd. has developed a sensor device using high-transparency organic piezoelectric film. This film has the following characteristics: (1) high piezoelectric output constant*1; (2) high transparency (light beam transmittance of 98% or higher [according to the internal haze measurement]); and (3) free from pyroelectric effect*2. This film can also detect twisting motion, and therefore there is high expectation for its application to various human machine interfaces.
Murata has newly developed devices that apply this piezoelectric film, such as a Leaf Grip Remote Controller that can control the TV using a bending and twisting motion and a "touch pressure pad," which is a touch panel that can detect pressure.
As smartphones, tablet computers, and portable game devices become more widespread, there is a growing demand for a new human/machine interface. Conventional piezoelectric films are usually subject to a pyroelectric effect, which is a disadvantage because they cannot detect bending and twisting vibrations separately from changes in temperature. Murata has developed a high-transparency piezoelectric film free from pyroelectric effect through joint research with Kansai University and Mitsui Chemicals Inc.
This remote control has a very new conceptual design that enables it to operate by bending and twisting of a plate made of piezoelectric films that can detect such motions. Furthermore, it uses pigments to discharge electrons when it receives light and is assembled with a photovoltaic cell that converts light into electricity to provide it with a battery-less feature.
Example of use
This remote control can operate a TV by bending or twisting of its plate.
"Touch pressure pad" -- Touch panel with pressure detection
Since this piezoelectric film is not subject to the pyroelectric effect, simply touching it with a finger does not generate voltage. As a result, the piezoelectric film is capable of high-precision detection. Furthermore, it can detect finger movement in the left/right and up/down directions as well as pressing force (how strongly it is pressed).
Example of use
Pressing the touch panel enlarges the data on the touch panel. This feature can be used to enlarge data quickly by pressing the panel with a strong force, and enlarge it slowly by pressing the panel with a weaker force.
We will exhibit these devices and provide demonstrations using these devices at CEATEC JAPAN 2011 to be held in Makuhari Messe in Chiba Prefecture from October 4th to 8th.
|*1 Piezoelectric output constant:||A value obtained by dividing the piezoelectric strain constant by the dielectric constant. This value is used as an indicator of sensor sensitivity. When this constant is higher, the sensor sensitivity is also higher.|
|*2 Pyroelectric effect:||A change in the temperature changes the surface electrical charge of dielectrics. The temperature change can be detected using a pyroelectric device.|
- Displacement sensor (sensor used for detecting bending and twisting)
- Touch panel
|Piezoelectric output constant (g31 conversion) :||180 x 10-3Vm/N|
|Displacement sensor:||Sample shipment planned for spring 2012
Note: The timing for commercial application of photovoltaic cells is not yet defined.
|Touch panel:||Sample shipment planned for autumn 2012|
Patents pending for approximately 30 items related to materials and applied devices.