Although originally developed for aircraft use, head-up displays have found application in automobiles recently. A system for evaluating automotive HUDs has been developed which is based on the double task method and takes into account driving conditions. Seven kinds of correct response rates (CRRs) are defined as the evaluation standard. Using various kinds of HUDs evaluations are made focussingly on the relation between the fineness of the images and the distance from a driver's eyes to the images. It can be concluded that the task of reading the HUD image rarely affects recognition of the forward view and is closely related to peripheral vision. This paper also discusses the index newly derived from the CRRs, which can represent the performance of HUDs. The results suggest there is an optimal fineness and distance to the HUD image.
It is important to create the proper luminous balance between main surfaces such as visual tasks and other room surfaces, as well as to satisfy visibility requirements for visual tasks on a personal working plane such as desk tops. The overall effects create comfortable office lighting. Recently task and background lighting techniques are often used. This system consists of general lighting providing low standard illuminance, and local lighting providing higher level illuminance on the desk to satisfy the visibility requirements for visual tasks. A series of experiments with subjective appraisals were carried out to clarify a preferable range of luminous balance in the office room, that is recommendable illuminance of the front wall and the surrounding desks, comparing to the illuminance of the visual task area on a desk. The experiments' results are as follows: (1) As a guideline for a typical lighting design, permissible illuminance range of the surrounding desks should be 270-500lx, and the wall illuminance should be 260-540lx, when illuminance of the visual desk is 700lx, and wall reflectance is choosen freely between 0.3 and 0.8. Here ‘permissible illuminance range’ doesn't mean optimum but between upper limit and lower limit of recommended condition. (2) When illuminance on the desk is choosen 500 and 1000lx freely or illuminance varies locally in the room, permissible illuminance range of the surrounding desks should be 270-500lx, and the wall illuminance should be 260-540lx. These results may be widely applicable to a comfortable task and background lighting design of a typical office room.
An attempt was made to intercompare the accuracy for the 3 methods of 253.7nm irradiance calibration. The first method, which we have already reported, is based on the silicon photodiode self-calibration technique. In this method, the absolute responsivity at 253.7nm of the photodiode was determined by the absolute responsivity at 632.8nm calibrated by the self-calibration technique and the relative spectral responsivity measurement. The second method uses a thermal detector calibrated by standard lamps and optical filters. The third method is a comparison measurement with the blackbody using a monochromator. The scales of 253.7nm irradiance realized by the three methods agreed within 1.5% and it is confirmed that each method has sufficient accuracy for primary standards of the 253.7nm irradiance.
Ozone decomposition capacity under the radiation of ultraviolet rays from a low pressure mercury vapor quartz lamp was studied. The lamp was made from a convential quartz tube. A main spectral line was 253.7nm in cylinder shaped 8W lamp. Spectral lines of 200nm or under were cut. Two ways were applied in the measurement. In the first experiment, the change of the exposing length of the lamp was measured at eight levels (1-105mm), keeping the width of the annular space constant (31mm). When the gas flow rate was brought down to about 0.11 1/min or under, ozone began to decompose notably. In the cases of small flow rate and long exposing length, each decomposition ratio was big. Additionally, considerations were given to ozone concentration decomposed in each exposing length (ppm/mm), and the relation between the exposing length and the decomposition ratio (%/mm). In the second experiment, the annular space was varied at eight levels (18-35mm), keeping the exposing length constant (105mm). Similarly, when the gas flow rate was brought down to about 0.12 1/min or under, ozone began to decompose notably. In the cases of small flow rate and large width of the annular space, decomposition ratio was high. Considerations were also given to ozone concentration decomposed in each annular space (ppm/mm), and the relation between the annular space and the decomposition ratio (%/mm).
The characteristics of hot cathode fluorescent lamps in low current regions (10-40mA) were investigated by experiments and numerical analysis. A quantitative correlation between the cathode fall voltage and the lifetime was obtained. If the cathode fall voltage is less than or equal to 14 V, arc discharge can be maintained stably during the lifetime, and hence, the life reliability of lamps can be improved. In order to reduce the cathode fall voltage for a given lamp current, it is effective to increase Ar gas pressure, and to decrease the surface area of the coils. The cold spot temperature is not effective to reduce the cathode fall voltage in the range of 10 to 60°C. The relation between the lamp design parameters and the cathode fall voltage was analyzed numerically on the basis of a modified theoretical model. The calculated results support the experimental results.
The research relates to the way to improve the power factor of a lag type operating circuit for high pressure mercury arc lamp with nonsinusoidal supply voltage. The research has been conducted in the following sequence. Firstly, nonsinusoidal voltage is supplied at the input terminal. Fourier series are developed on voltage and current of distorted wave at each element of the operating circuit, and at the same time experiment is performed. The following are derived from the results of the research. (1) We have obtained a formula by which to calculated the value of a optimum condenser compensating the power factor on condition that the minimum apparent power is supplied. (2) It is proved that the higher power factor can be realized by applying a series reactor (inductance: L) and capacitor (capacitance: C) are connected in parallel with the input terminal in order to make the power factor of the fundamental wave at the power source 1, 0.
Influences of relative humidity on the formation and decomposition of ozone by ultraviolet radiation from a low pressure mercury vapor quartz lamp were studied. Main spectral lines of the lamp for formation were 184.9nm and 253.7nm, but it for decomposition was 253.7nm. The lamps were made in cylinder shaped, and were 8W. Two ways were applied in the measurement of the relation between gas flow rate and ozone produced. In the first experiment, the relative humidity of the feeding air was varied at eleven levels (0-100%), keeping the temperature constant. When the gas flow rate was 54/min or under, the produced ozone concentration decreased with enhancement of relative humidity. The decomposition ratio of ozone was maximum at the gas flow rate of 0.11l/min independently of the relative humidity. And, influence of relative humidity was not recognized over the gas flow rate of 5l/min or over. Additionally, considerations were also given to the relation between the relative humidity and maximum ozone concentration, and the relation between the relative humidity and decomposition ratio of ozone at each maximum concentration. In the second experiment, the relative humidity of the feeding air was varied at ten levels (0-80%), keeping the temperature constant. The decomposition ratio became high increasing relative humidity, and it was high at the gas flow rate of about 0.11l/min or under, and it decreased with increasing gas flow rate. And, influence of relative humidity was not almost recognized at the gas flow rate of about 3l/min or over. Equations between relative humidity and maximum ozone concentration, and decomposition ratio in each gas flow rate were obtained. Other considerations were also given to the ozone concentration produced only by the ultraviolet ray of 184.9nm radiated from the ozone formation lamp after the careful analysis of the relation between the inital ozone concentration in the formation reaction and the residual ozone concentration in the decomposition reaction.
The absolute responsivity of seven different types of silicon photodiodes manufactured in Japan and in the U. S. has been measured on 442nm, 488nm, 544nm, and 633nm by the self-calibration technique. The absolute accuracy obtained for each type of photodiode has been verified by a comparison with a standard detector calibrated against an ESR. Of the seven types of photodiodes, three types including p-n types manufactured in Japan and an n-p type manufactured in the U. S. have been proved to have an absolute accuracy of better than ±0.3% on all the four wavelengths. The differences of the structure and the various characteristics of each type of photodiode related to the self-calibration technique are discussed.