Hirotoshi Terao

Measurement of Performance Characteristics of a Piezoelectric Micro Blower

This study conducts a measurement system of a performance of a piezoelectric micro blower. Electronic equipments such as laptop computers and cellular phones become smaller and thinner while their functions become more complex. As a result, a lot of components are mounted in an electronic enclosure and flow passages for the cooling air become narrow. This causes significant pressure drop and general cooling fans cannot supply enough cooling air. To improve cooling performance in small electronic equipment, a new air supply system which combines smaller and thinner size with a high pressure performance characteristic is needed. We focused on a novel piezoelectric micro blower. This blower can supply the airflow with high static pressure using the vibration of the piezoelectric element. This may produce a forced convection cooling with low electric power regardless of the size of electronic equipment and packaging density of electrical devices. However, to predict accurate cooling performance of the piezoelectric micro blower in thermal design, we have to obtain a correct supply flow rate of the blower because the cooling performance of forced convection is significantly dependent on the supply flow rate. Generally, an operating point of the blower, which is the operating pressure and the flow rate in electronic equipment, is the point of intersection of performance characteristic curve, which is the relationship between the blower’s pressure rise and the supply flow rate, and flow resistance curve in equipment. Therefore the measurement of the performance characteristic curve is most important.We tried to develop the measurement system of the performance characteristic curve of the piezoelectric micro blower with high accuracy. We succeeded to measure the relationship between the supply flow rate and the static pressure rise of the micro blower. Moreover, in order to clarify whether the micro blower is available for a cooling method of high-density packaging electronic equipment or not, we tried to investigate the effects of the obstruction, which is mounted in front of the blower, on the performance characteristic. Then, we confirmed whether the performance of the blower is changed by the components mounted near the blower or not.Copyright

Basic Study on Transient Temperature Response of Papers in a Thermal Transfer Printer

This study describes temperature response of papers in a thermal transfer printer. Thermal transfer printer produces an image by heating heat sensitive papers using a thermal head. The print quality of the thermal printing is highly dependent on a temperature response of the paper.Our research targets to develop a control technique of temperature of the printing paper to improve the print quality of the thermal transfer printer. In this report, our special attention is paid to investigate the temperature response of a paper when the heat is applied by the thermal head. The temperature transient in the paper is measured while changing the type of the paper. Moreover, in order to investigate a relationship between thermophysical properties of papers and the temperature response, the thermophysical properties are measured. A thermal network analysis is additionally performed and the effects of a contact resistance between the paper and the thermal head are also investigated. It is found that transient temperature response of the printing paper is strongly dependent on a type of the printing paper and the level of an input heat. A change of the temperature response is caused by the difference of thermophysical properties of the paper and a variation of a contact resistance between the paper and the thermal head.Copyright

Evaluation of Printing Papers for Thermal Transfer Printers Based on Real Contact Area Using a Contact Microscope

The thermal transfer print method is to print ink on the surface of paper by pressurizing ink and paper directly with a thermal head, and heating the places to print. A principle of the thermal transfer printing is similar to that of the offset printing. A tribological contact problem occurs in the offset printing. Thus the thermal transfer printers are suffering from the similar contact problem between the ink and the paper since the surface of the plain paper has roughness and it is very difficult to make the contact situation constant at all time. It is necessary to deeply understand the contact between paper and the solid ink to achieve the high-resolution printing on even the rough plain paper. So far the stylus type and the laser type profilometers were used to evaluate the printing quality for various papers. However there is no attempt to examine the printing quality, optical density, from the view point of real contact area. Then, the relationship between the optical density and the real contact area on the paper side was experimentally obtained in this paper with a contact microscope. As a result, the correlation could be found between the optical density and the real contact area.

Effects of Anisotropic Sub-layer on Heat Conduction Control in a Thermal Print Head

In order to develop a high-speed and high-resolution thermal printer, it is required to improve a heat conduction in a thermal head which leads to a uniform temperature. On the other hand, a moderate heat insulation might make thermal printers more energy-saving. Thermally anisotropic materials seem to be promising for these purposes. It can flatten the temperature distribution in a desired direction while preventing heat flow to the other direction. In this study the feasibility of the anisotropic sub-layer substrate is examined both experimentally and computationally. Carbon fiber composites are used to make thermal heads and the distribution of temperature is evaluated. The result shows that a control of the heat conduction in a desired direction is possible. To improve the controllability of heat conduction, the neural network is applied to seek the optimum composition of heat conductance.

Analysis of Contact Pressure Acting on a Thermal Print Head of a Thermal Transfer Printer

The printing method of the thermal transfer printer is to push an ink ribbon that is heated and melted by a thermal print head to a printing paper, and transfer the ink desired positions on the paper. Thus it is important to place the heater of the thermal print head at the position where the contact pressure is most high. The visco elastic properties of the ink, PET and platen rubber were measured with a rheometer. The contact pressures on the thermal print head were calculated by FEM. The contact pressures under consideration of visco elasticity were different from those calculated by elastic analysis. The effect of sliding speed of the thermal print head on the contact pressures was also examined. To examine the effect of the contact pressure on the print quality the optical densities were measured with the heater positions of the thermal print head changed. The optical densities were changed with the heater positions. It can be found that the optical densities decreased with the calculated contact pressure.