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The aims of this study are to understand the mechanism of dew condensation and try to prevent it on automobile headlamp. In this case, it is necessary to build the computational model of the headlamp with all details accurately. In addition, the simulation framework for predicting the turbulent flow field has to be accompanied with the high temperature heat source and consider high accuracy of the wall heat transfer in the running environment of a vehicle. Moreover, it is a challenging task that using CFD (Computational Fluid Dynamics) to understand the mechanism of the flow field inside the light emitting diode (LED) headlamp with a rotating fan to cool the light sources because of the complicated internal structures and significant heat transfer. In this paper, the method of compressible turbulence has been constructed which based on hierarchical cartesian grid using the HPC (High Performance Computing) environment.

LEDs have been applied to automotive exterior lighting more and more. Compared with incandescent lamps, LED light directivity is variable by changing epoxy resin lens form. This characteristic has enabled us to develop a new system in which oval light distribution pattern is formed by combining direct beams from LED and reflected beams on a reflector, resulting in 30% beam availability improvement. Our development concept in this paper is based on the fact that newly-looking thin marker lamps have been demanded because they affect the total image of a car.

This report details our development of a smoothly curved inner lens for use in automotive signalling lamps. Such a lens allows for greater freedom at the design stage of an automobile, and it can be useful for economizing on space. Until recently, however, the design of such lenses has been in difficulty due to the complex geometries involved, and the appearance and light distribution has often turned out to be inferior to that of conventional plane and spherical lenses. The main reason for this is that in the case of these conventional lenses, optical calculations can be reduced to simple equations, but this is generally not possible with smoothly curved lenses. Our goal has been to develop a smoothly curved inner lens whose optical characteristics could be calculated and verified. This development project can be divided into three stages: design, processing, and evaluation. We are currently developing the third stage.

1 This report describes the development of an automotive radar system which uses a laser diode as a light source. The time taken for a laser beam to travel to a vehicle ahead and to be reflected back is used to calculate distances between vehicles. This information is further processed and compared with continuous calculations of safe distances. When the actual distance between vehicles becomes less than the estimated safe distance, an audio warning signal is issued to alert the driver.

With the increased use of wraparound lamps in automotive design, the problem of how to illuminate the lateral section which is blocked from the light source by the chassis has become a point of concern. This report describes the development of an optical system which makes use of a photoconductive panel in order to resolve this problem.

These headlighting systems control the headlamp beams according to the running state of a vehicle at night in order to provide optimal illumination. They have two functions: to control the range of illumination according to vehicle speed and to control beam direction in response to the steering. Two optical systems were developed to realize these functions. One system uses two movable mirrors in each headlamp, while the other system uses a movable lens installed in front of the projector lamp. According to photometric data analysis done in our laboratory, bath systems improve visibility on curved roads substantially. It was also found that they are effective in limiting glare projected onto oncoming vehicles.

The demand for headlamps with low profile and slant lens has been increasing in such a vehicle styling trend that it has been getting more and more aerodynamic to reduce air resistance and thereby to improve fuel consumption and driving performance. Lamp manufacturers, in answer to the demand, have tried to develop various types of new optical headlamp systems. We, Koito Manufacturing Co., Ltd., have been also studying and developing our own low profile headlamps and now we have found a new optical system which can be applied to such a severe condition of 65 mm in height and 45° of the outer lens slant. Here we report the details of the development.

This is a report on the development of a lamp system that will change the extent of the illuminated area in response to the steering angle. The optical performance of headlamp systems has been improved in response to increases in automobile performance and changes in traffic conditions. However, most of a driver's perception at night is visual so it is necessary to improve the driver's forward visibility at night in accordance with the increased performance of automobiles. The light distribution of current headlamps is designed mainly in consideration of straight forward vehicle movement so the area that a driver wants to see when making a turn is not necessarily sufficiently illuminated. In order to provide sufficient illumination for safe cornering, a headlamp system that changes the distribution of light in response to the steering angle with the use of microcomputer control has been developed.