Wen Jong Wu

High-powered Backlight Inverter for LCD-TVs using Piezoelectric Transformers

In this study, an innovative design of a high-voltage, high-powered, low-cost backlight inverter based on piezoelectric transformer technology for lighting long cold cathode fluorescent lamps (CCFLs) on large size LCD-TVs is presented. Three innovative design thoughts are introduced here. First, the quasi-modal electrode is used as the input electrode of the piezoelectric transformer. It is shown that a full modal filtering effect is achieved. In other words, all unwanted vibration modes of the structure are suppressed, which eliminates all higher harmonics of the input voltage. The second one is an innovative rigid support design which can enhance the modal filtering effect, which can also be used to replace thin input wiring and lead to lower contact resistance. The third innovative design uses direct switching on the rectified voltage from the power line (110/220V). With direct line voltage input, a single layer Rosen-type piezoelectric transformer (PT) can have enough gain to generate a high voltage to light long length CCFLs instead of using high cost multilayered PTs. A piezoelectric transformer-based inverter based on the above design considerations is built and verified in this study.In this study, an innovative design of a high-voltage, high-powered, low-cost backlight inverter based on piezoelectric transformer technology for lighting long cold cathode fluorescent lamps (CCFLs) on large size LCD-TVs is presented. Three innovative design thoughts are introduced here. First, the quasi-modal electrode is used as the input electrode of the piezoelectric transformer. It is shown that a full modal filtering effect is achieved. In other words, all unwanted vibration modes of the structure are suppressed, which eliminates all higher harmonics of the input voltage. The second one is an innovative rigid support design which can enhance the modal filtering effect, which can also be used to replace thin input wiring and lead to lower contact resistance. The third innovative design uses direct switching on the rectified voltage from the power line (110/220V). With direct line voltage input, a single layer Rosen-type piezoelectric transformer (PT) can have enough gain to generate a high voltage to light long length CCFLs instead of using high cost multilayered PTs. A piezoelectric transformer-based inverter based on the above design considerations is built and verified in this study.

Development of 2D Microdisplay Using an Integrated Microresonating Waveguide Scanning System.

Our research team has developed a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high-image resolution and field of view obtained by mirror-based display systems. The basic design of the optical scanner includes a microfabricated SU-8 cantilever waveguide that is electromechanically deflected by a piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the actuator and the LED light modulation are generated and controlled using a field programmable gate array. Our recent study is an update to the previously-reported mechanical scanner, replacing the hand-built PZT scanner and fiber waveguide with a microfabricated system incorporating aerosol-deposited PZT thin film and a polymeric SU-8 wave guide. In this article, we report on the design and fabrication of a prototype miniaturized 2D scanner, discuss optical and mechanical the modeling of the systems properties and present the experimental results.

Development of a polymer based fiberoptic magnetostrictive metal detector system

This paper presents a new metal detector using a fiberoptic magnetostriction sensor. The metal sensor uses a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing material. This polymeric magnetostrictive fiberoptic metal sensor is simple to fabricate and small in size. In contrast to electromagnetic type metal detectors, this fiber optic metal sensor is resistant to RF interference. Metal detection is based on disruption of the magnetic flux de nsity across the magnetostriction sensor. In this paper, characteristics of the material being sensed and magnetic properties of the ferromagnetic polymers will be discussed.

A wireless composite optical bend loss sensor for pressure and shear measurement

A composite optical bend loss sensor for measuring 3-D forces has been developed. The sensor is composed of two optic fiber meshes which are embedded into a polydimethylsiloxane (PDMS) slab. The sensor consists of an array of optical fibers lying in perpendicular rows and columns sandwiched inside an elastomeric pad. A map of normal and shear stress is constructed based on observed macrobending through the intensity attenuation from physical deformation of two adjacent perpendicular fibers. Due to the new addition of the composite design and acrylic holder, the stability of the present sensor is found to be significantly better than our previously reported microfabricated optical bend loss sensor. In this paper, we will report the results of an optical bend loss simulation using the beam propagation method based on a series of images captured by a CCD camera on the fibers bending curvatures. The result from the simulation will be compared with the results obtained from the experiment. Other results include vertical force and shear measurements at a single pressure point of the sensor. A force image algorithm is used to map the force distribution detected by the sensor. Here, we will present the results of six different shape patterns and two force magnitudes on each shape using a neural network system. We will also present a radio frequency sensor module, which we developed for the composite optical bend loss sensor for remote sensing.

Development of a novel polymeric fiber-optic magnetostrictive metal detector.

The purpose this paper is the development a novel polymeric fiber-optic magnetostrictive metal detector, using a fiber- optic Mach-Zehnder interferometer and polymeric magnetostrictive material. Metal detection is based on the straininduced optical path length change steming from the ferromagnetic material introduced in the magnetic field. Varied optical phase shifts resulted largely from different metal objects. In this paper, the preliminary results on the different metal material detection will be discussed.

Development of a polymeric magnetostrictive fiber-optic sensor system

A polymeric magnetostrictive fiber-optic sensor is presented. The sensor uses a newly developed ferromagnetic polymer (WCS-NG1) as the magnetostrictive coating for magnetic field detection. A simple fiber-optic Mach-Zehnder interferometer is deployed; where magnetic field induced magnetostriction effect is detected based on the phase modulation measurement. The magnetostrictive effect has a number of advantages of sensor. It is relatively simple to fabricate on the optical fiber. Optical technique also provides high sensitivity in its measurant. Therefore, magnetostrictive effect is used for the fiber optics magnetometer. Comparison with Tefonol or other conventional magentistrcition sensors, this novel polymeric magnetostrictive fiber-optic sensor is much less complex relatively smaller in size, and optical technique also prevents RF interference that is common in typical electromagnetic type sensors. In this paper, characterization of the material and magnetic properties of the embedded polymer will be discussed. Preliminary results on the magnetic field and current sensing will be presented.

Flexible patch composed of PZT thin-film on stainless steel foil for energy harvesting from low-frequency human motions

To harvest energy from human motion and generate power for the emerging wearable devices, energy harvesters are required to work at very low frequency. There are several studies based on energy harvesting through human gait, which can generate significant power. However, when wearing these kind of devices, additional effort may be required and the user may feel uncomfortable when moving. The energy harvester developed here is composed of a 10 μm PZT thin-film deposited on 50 μm thick stainless steel foil by the aerosol deposition method. The PZT layer and the stainless steel foil are both very thin, thus the patch is highly flexible. The patch can be attached on the skin to harvester power through human motions such as the expansion of the chest region while breathing. The energy harvester will first be tested with a moving stage for power output measurements. The energy density can be determined for different deformation ranges and frequencies. The fabrication processes and testing results will all be detailed in this paper.

Fiberoptic metal detector capable of profile detection

The purpose of this paper is to develop a novel ferromagnetic polymeric metal detector system by using a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing device. This ferromagnetic polymeric metal detector system is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is made possible by disrupting the magnetic flux density present on the magnetostrictive sensor. This paper discusses the magnetic properties of the ferromagnetic polymers. In addition, the preliminary results of successful sensing of different geometrical metal shapes will be discussed.

Aerosol deposited PZT actuated 2D scanner system

A new lead-zirconium-titanate (PZT) actuator design for a micro scanning illuminating device is being developed. The thin PZT film is deposited directly on stainless steel by using an aerosol deposition machine. The aerosol deposition method enables inexpensive, quick, room temperature fabrication while producing high quality PZT films. The presented scanners would be attractive for endoscopic device applications, where inexpensive systems with high resolution would be a move toward disposal endoscopes. The design of this scanning illuminator and fabrication method are presented. Measurements of the PZT layer surface roughness and the aerosol deposited PZT powder particle diameter are presented. Ongoing work and fabrication challenges are discussed.

Design of a PZT Actuated Cantilever Waveguide Scanner Using an Aerosol Deposition Process

A new lead-zirconium-titanate (PZT) actuated scanning light source design is proposed. An Aerosol deposition process will be used to construct a high quality 5 μm thick film of PZT. The PZT actuator will induce non-linear vibrations to scan an area with a cantilever waveguide. The fabrication procedure for the design is presented. Fabrication results are discussed. A finite element analysis of the actuator pad is also presented. Fabrication steps needed for a comparison of the amplitude of actuation, resolution, and frequency of scan with previously developed Si based devices are also discussed.