Key Engineering Materials Vols. 364-366

Abstract: Head lamps, tail lamps, side lamps, roof lamps, alarm signal lamps and other lamps of an automobile constitute a whole lighting system, and identifying devices constitute a guarding system against theft and alarm. In traditional designs, each lamp is independent and controlled artificially by persons, and the automobile cannot show maintenance men which lamp is broken-down and needs mending or replacing. The lamp is either ON or OFF, and its luminance can be adjusted neither automatically nor artificially so that much energy goes to waste. Moreover, lighting system is isolated from identifying system so that they are difficult to manage by a uniform system. Currently, identifying systems of many automobiles key system, door-controlling system, UHF sending/receiving system, alarm system and so on. Once the key is lost or stolen, those persons that have not the ownership can also open the door of the car with it. In this paper, an ISO Standard (ISO 11898) for serial communication- CAN is introduced. Through CAN micro-controller provided by ATMEL, each lamp of lighting system is a component and can be interconnected. Identifying system, in which fingerprint encryption technique is utilized, can also be interconnected with lighting system. This system can be controlled completely, and has some advantages such as smartness, security, low power, low cost, etc.

Abstract: Thermal field analysis for automotive lamps is a complicated thermodynamics problem. According to the features of structure and lighting process of automotive lamps, a simple and convenient model is put forward here for analyzing their thermal field. Under certain assumptions, it simplifies the complicated geometrical structure to the relative simple cavities and only considers the influence of thermal conduction and thermal radiation as main forms of heat transfer for thermal field of the lamps. The consistency of numerical analysis and actual test demonstrates that this modeling method calculates thermal field of the lamps quickly and perfectly, and indicates its practical signification.

Abstract: As a new kind of light source, LED light source has found wide application in many fields, especially in automotive lamp light source with the rise of luminous efficacy. The paper puts forward an iterative model, which approximates the light intensity variation of LED by adding up a series of the luminous flux of sub light sources with uniform light intensity, and accurately reflects the attenuation feature of LED light intensity. As long as the tracing ray is sufficient, the calculation error will be very small, and the result ideal, thus making it suitable for engineering application.

Abstract: This paper proposes a backlight system that generates the regular dot pattern on the bottom of light guide to achieve uniform luminance. The simulation program employs the variable r-cut technique combined with some regular dot pattern such as shift-rectangular, hexagonal and so on. The r-cut technique based on molecular-dynamic method, was first bought up to apply in the random dot pattern. By using such a technology, we could easily evaluate the right range of radius within each cell to get the general dot distribution according to the specific position away from light sources and the sources properties, after we divided the total effective domain into several sections of cells. In the end we made some fine-tuning on the boundaries to obtain the final result. It has been revealed in the simulation that the light guide can achieve a uniformity of more than 90% and optical efficiency about 26%. What we have more interest in are the optical properties that have much influence on both the uniformity and the optical efficiency. Particularly when it comes to larger size backlight products used in PC screen for instance, it will have a great impact. Several figures in this paper also illustrate the dots distribution and the illuminance distribution.

Abstract: At present, the large backlight modules, used in illuminating advertising pictures, are designed and developed in various specifications, whose common goal is to try to manufacture thinner backlight modules and produce more uniform illumination. The currently well developed backlighting technology for liquid crystal displays (LCDs) can be transformed and used in such an area. However, the design of edge-lit backlight with size of over 1 square meter has great difficulties in eliminating the phenomenon of non-uniform illumination. In this paper, the application of Bezier curve in the simulating the dot pattern on the bottom of light guide is presented, which directly determines the final light extraction efficiency and illuminating uniformity. Taking the RMS deviation of illuminance values at several sample positions as the merit function, the shape of Bezier curves can be smoothly changed, so that the dot radius can be optimized in a fast and efficient way. Such an optimization procedure uses only two variables and has a fast convergence. As an example, a large light guide, 800mm×1000mm in size, was designed by applying the Bezier method, and the final uniformity of 70% was achieved. The most prominent feature in such a method is that the thickness of designed light guide can decrease to 5 mm. In sum, the large sized edge-lit backlight can be designed in a short optimization period by simulating the dot radius distribution in a shape of the Bezier curve.

Abstract: The curvature spectrum causes the light energy within one spectral line cross several CCD pixels in minitype spectrometer and decreases the resolution and sensitivity. To solve this problem, a special vertical binning method for area image sensor is proposed. During the vertical binning, the position of the electron package is moved in CCD horizon register. The energy center of the same spectral line is always kept in the same electron package. Experiment has shown this method as achievable and effective. The FWHM of Hg 576.960nm spectrum has been reduced to 0.21nm from 0.27nm and the peak intensity increased to 38513ADU from 28428ADU.

Abstract: With advances in micro fuel cell development, the production of hydrogen for micro reformer has become increasingly important. However, some problems regarding the micro reformer are yet to be resolved. These include reducing the size, reducing the quantity of CO and combining the fuel cell, among others. Accordingly, in this investigation, array micro temperature sensors and heaters were combined within a silicon-based micro reformer to measure and control the temperature and thus improve performance and minimize the concentration of CO. In this work, micro-electro-mechanical-systems (MEMS) of the micro channel type were fabricated on a silicon substrate to enhance the methanol conversion ratio. Array micro temperature sensors and heaters were made of platinum and placed inside the micro reformer. Although the micro temperature sensor and heater have already been used to measure and control temperature in numerous fields, they have not been employed in micro reformer and commercial products. Therefore, this study presents a new approach for combining array micro temperature sensors and heaters within a silicon-based micro reformer to minimize the size and improve performance.

Abstract: Sun sensor is one of the key attitude sensors widely used in spacecraft attitude determination. Its accuracy is one of the major technical specifications. In this paper, we propose two methods for accuracy test and evaluation, which have been proved to be efficient and convenient. With these two methods, it is possible to isolate and then, eliminate the rotational error from the rotation table that holds the sun sensor so that the performance of the sun sensor can be evaluated. The proposed two methods can be also applied to test the performance for other angle measuring devices.

Abstract: High speed imaging with decent image quality is difficult because the available exposure times are very short, which leads to the usage of a large aperture. Unfortunately, large aperture also decreases the depth resolution of the system, which reduces the quality of the image. Thus the source of illumination has to be able to output a high amount of energy in a very short time so that the aperture requirement can be relaxed. There are only a few Xenon flash lamps that fulfill the requirement of sub-microsecond pulses, so the natural choice would be to use lasers. However, when the target surface is rough, high degree of coherence causes black and white interference patterns known as speckle. The sensor might register irradiance values from zero to saturated state. Needless to say, this reduces drastically the quality of the image. There is variety of techniques for speckle removal, ranging from chaotic laser states to digital signal processing [1-5]. In this paper we discuss an alternative, namely LEDs, for this kind of illumination. The authors have performed some experiments and theoretical modeling, and successfully demonstrated an illumination system based on LEDs that can output enough energy to enable imaging with pulse lengths of 100 ns.