Taguchi methods requires two step optimization in any product design. The first step is a robustness development against all customers usage conditions and the recond an adjustment it to perform the target function at normal usage condition. The later is called adjustment or turning. The first step uses Signal to noise Ratio as a robustness measure against various customer's usage conditions but the second uses mean square error around the target function at normal usage condition.

Instead of traditional least square methods to calculate the error variance around target function, a new method is proposed here. The method is most useful to estimate the error variance. It is the method to use an orthogonal expansion around the target function from observed function at several levels of signal at confirmation stage after robustness optimization.

Our company has developed a type of belt which consists of thin nickel base material for the color fixing process. By using this system, the time of waming up can be completed in a short period. The life of this fixing unit is limited by the cracking of the belt, probably caused by the fatigue of metal. In order to improve the material, it was considered important that the voltage/current relationship be least affected by frequency variation. After conducting a parameter design, a new material was developed before product development spending only a half year. As a result, the belt life caused by cracking was extended three times compared with the current material.

This is a study of applying On-Line Quality Engineering methods to improve the calibration of a measuring system to be used for a new product production. The optimum calibrating conditions were determined by balancing the loss due to quality with the costs of checking and adjusting. As a result, it was found that the calibration of a measuring system for a new product could be improved. It was also found that the measuring cost could be reduced while quality is maintained.

In recent years, cold cathode fluorescent lamps are widely used for liquid crystal displays and scanners. In this study, the generic function for cold cathode fluorescent lamps using the transient characteristic was optimized. The function was evaluated by observing brightness and the starting characteristic of lamps.

Thermal paper is used for a variety of products such as labels, facsimiles, word processors, printers, electric blackboard printers and handy terminals, etc. Label paper consists of base paper, undercoating layer, thermal layer (heat sensitive layer), over-coating layer and back-coating layer. The thermal layer which performs the main function of themlal paper consists of dyes, coloring agents, fillers and binders. In this report, the optimization of the formulation of themlal paper labels for the POS food market using a new coloring agent was conducted. It was aimed to prevent the detehoration of image quality under usage conditions. Results of the study showed a better initial quality compared with the current product and a robust quality under vahous usage conditions were obtained.

As the generic function, the energy generated from tile thermal head was considered as the input signal and image concentration as the output response. Zero-point proportional equation was used for analysis. As the noise factor, eight levels including seven deterioration modes and the initial condition were experimented. As many as eight levels were experimented because of the difficulty to compound noise factors such as mixing oil and water.

In the market of copy machines and printers using the electro-photographic system, the demand for coloration is becoming stronger. There are many coloring processes for copy machines and printers. Our company adopts a developing system called the KNC (Konica, New, Color) system. The system has the possibility to miniaturize the unit. But it was believed that there might be a difficulty to improve stability. In this study, test pieces were used to successfully evaluate the functionality of the development process. Also the study was completed efficiently.

In recent years, the demands of high productivity and quality for copy machines and printers is getting stronger. To respond such demands, it is important to develop both machines and the developers used in the machines. In the traditional approach to develop the developer, the quality level of a developer is judged by the output of image. However, such development using actual machines takes time and is costly because a large amount of developer has to be consumed. It is therefore urgent to find a more efficient approach. To evaluate the function of a developer, time was introduced in the generic function, and test pieces were used to shorten the time of development and reduce the cost.