This paper describes a formulation by which one can obtain spectral power distributions of fluorescent lamps with any correlated color temperature T_c, and with any general color-rendering index R_a, provided that their chromaticity points lie on the daylight locus or the plankian locus.
The spectral power distribution J (λ) is constructed by a linear combination of the averaged spectral power distribution J₀ (λ) and three characteristic functions T₁ (λ), T₂ (λ) and T₃ (λ) as follows:
J(λ) =J₀(λ) +h₁T₁(λ)+h₂T₂ (λ) +pT₃ (λ)
In the equation, T₁ (λ) and T₂ (λ) are derived so that the first and the second coefficients h₁, h₂ are determined by correlated color temperature T_c, irrespective of R_a. The third coefficient p is related to both T_c and Ra. An approximated formula is derived which relates p with R_a including Tc as parameter.
The formulation is applied to derive the spectral power distributions of fluorescent lamps with T_c ranging from 3000 K to 7000 K and with R_a of 50 to 94. The computations reconstitute well the spectral power distributions of fiuorescent lamps having the pre-specified values of T_c and R_a. The mean error in R_a is 0.14.

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Conditions for precisely measurement of the spectral sensitivity of radiation detectors in the wavelength region of 230 to 760 nm are discussed and the desired characteristics of the measuring instruments are indicated. There are the response characteristics of the standard and reference detectors, the uniformity of monochromatic irradiance on the detector surface and the uniformity of sensitivity in the receiving surface of the detectors. Errors which occur due to the varying nonuniformities of the monochromatic irradiance and of detector sensitivities depend on the wavelengths are also estimated.
A PVF₂ pyroelectric radiation detector with receiving area of 10 mm diameter coated by gold-black, whose spectral absorptance is directly measured, can be used as a available practical standard having proper response characteristics with known spectral sensitivity. The uniformity of the monochromatic irradiance is improved by the use of a concave mirror incident system for the monochromator and an exit optical guide consist of an optical fiber bundle.

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At a crossing in a road, we have often found that the go-signal called as a “blue signal” does not appear blue, sometimes they are rather green. Such an inconsistency of the designation with the apparent hue of the signal light is an undesireble visual environment. The recommended color boundaries in the chromaticity diagram for the light signals of road traffic control in Japan are considerably different from the CIE recommendation especially as concerns the “blue signal”. The apparent hue of the lights in that “blue” region has never been evaluated quantitatively. We investigated the hue of those lights employing the color naming method for 3 subjects. The results showed that most of the lights are not blue, but greenish-blue or bluish-green. They are not psychophysically unique hues. The same method was used to evaluate the apparent hue of the “blue signal” s in the city road. Resulted responses pointed out that a variety of hues, from pure blue to yellowish-green, are existed. Because a blue light has some disadvantage for signal light considering the characteristics of our color visual systems, the green light and the term “green signal” should be most suitable for the traffic control signal.

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This paper is concerned with the development of a vehicle-borne optical sensor, which is useful for recognition of the moisture of various pavement surfaces as one of the parameters for vehicular antiskid control. The principle of this sensor is based on an increase in degree of polarization of the light flux reflected from the surface with an increase of its wetness.
The light flux reflected from a specular surface, e. g. completely wet surface, is horizontally polarized well, when the incident angle is the Brewster's one; whereas, the light flux reflected from a diffuse surface, e. g. completely dry surface, is almost unpolarized. By making a measurement of the degree of polarization of the reflected flux, we can completely discriminate between the dry-and wet-surfaces, when the success probability of the classification is perfect.
The increase in degree of polarization among the change from the dry-to wet-status results from the increase of the part of the specular reflection area occupied in the optical field-of-view to be tested.
The degree of polarization of both the frozen and snow-covered surfaces (in Hokkaido area) was slightly smaller than that of the dry surface; so that, both of them should seem to be diffuse surfaces. It is difficult, therefore, to distinguish the frozen and snow-covered surfaces against the dry one with the classification probability of more than 90%.

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The Calculation of luminous transfer in spaces bounded by surfaces that exhibit specular and/or diffuse reflections were extensively studied by O'Brien and associates in the middle of 1960's.
In the conventional calculation, the number of terms of the φ-function and consequently computation time increase as the number of surface elements increses.
This paper describes an approximate calculation of interreflections in rooms with both diffuse and specular surfaces. The approximation is based on the assumption that surfaces with both diffuse and specular reflections can be treated solely as uniform diffusers for any interreflection.
For evaluation, luminous exitance is calculated for luminous panels of different sizes in a room of any shape.
The results showed that approximation errors were less than one percent.

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In the preceding paper, a new formula for the estimation of the efficiency of daylighting through an optional rectangular duct was proposed. That formula was founded on the calculation of the total illumination at the end of a duct given by luminous emittance, from the incident opening itself and its innumerable multiple-reflections in the specular surfaces on every inside wall. Conseqently, the proposed formula depended necessarily on a computer for the calulation, then, its wide and easy application cannot be expected.
In this paper, the formula is simplified so as to be utilized without aid of computer, and an approximate formula by which the calulation for the estimation of daylighting efficiency of a dudt can be manually performed is introduced.
This formula is expressed by the summation of three terms, separately, composed of an exponential function, where, as variables, all kinds of factors necessary for the design of a duct, namely, the size of a section, the length of a duct, and the reflectance of inside surface are included. Furthermore, it is shown that this formula has only a slight error in the computation less than ±2% compared with the computed values in accordance with the original formula.

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Using a new transistor inverter, fluorescent lamp ballast of light weight and high efficacy is achieved.
The inverter is composed of a power transistor, a semiconductor diode, two small inductors, two capacitors and trigger unit which drives the power transistor.
Switching the power transistor with LC circuit, a. c. power of 15-20 k Hz is generated to operate fluorescent lamp.
The inverter has features suitable for a ballast.
(1) Output voltage is much higher than the source voltage and decreases with decreasing value of load resistance. Hence it is possible to operate the lamp with source voltage lower than tube voltage.
(2) Output current is approximately constant at lower value of load resistance. The characteristics is favorable to regulating the lamp current.
(3) Output power depends on the trigger frequency. The characteristics is useful for dimming or lighting controls and also useful for regulating the lamp power against the fluctuation of source voltage.
Using the inverter, the 20 watt lamp ballast with 24 volts source and the 80 watt lamp ballast with 100 volts source are made.
The ballast is simple compared with other electronic ballasts. Single power transistor is employed and step-up transformer is not used.

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Even in the steady work, worker's line of sight is usually directed to various directions from time to time. When the difference in luminance of the visual field before (L₁) and after (L₂) is not small, his eyes are not in adapted condition to L₂ for a considerable time after the shift of viewing direction. In this transition period of time, there happens the deterioration in his visual sensitivity. There occurs serious drop in his visual acuity immediately after the change of visual direction, and gradually it is restored to the normal acuity corresponded to the adaptation luminance L₂. In the present stage of lighting evaluation and design, there is no regard to the fact mentioned above.
The purpose of our research is to introduce the dynamic concept in the present steady design of lighting considering the eye movement. In this paper, the results are reported which obtained by the visual acuity tests in the transition stage of adaptation for various combinations of L₁ and L₂ using uniform luminance field of view. General character can be revealed as to the recovering process of visual acuity.

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Visual evaluation for the luminous environment has been investigated customary the condition in which the subject's eyes are perfectly adapted to the given luminous environment. But in the actual conditions, worker's eyes are not always fi xed to his visual task. Usually his line of sight is directed to different directions from time to time, and in consequence, the luminance of his visual field changes abruptly from L₁ to L₂ together with his eye movement. When L₂ differs greatly from L₁, his eyes are in transition stage of adaptation for a considerable time after an abrupt change in luminance, andin this period his visual sensitivity is never the same as that in perfectly adapted condition to L₂.
Visual evaluation tests were performed in transition stage of adaptation for various combinations of L₁ and L₂. In this paper, the results of tests with regard to glare sensation in the case of L₂>L₁, and discomfort in the case of L₂<L₁ using visual field of uniform luminance are reported. The distinct difference of glare senration from that in steady state proves the necessity of introducing the dynamic concept in evaluation and design of luminous environment.

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Integration of daylight and electric light is one of the important lighting factors in the unilaterally lit office room in the daytime. The unilateral lighting brings some problems differ from ordinary artificial lighting, as the luminance of the wimdow is almost the same as that of the fluorescent lamp lighting fitting, but the area of the window is much larger, and as the direction of flow of daylight is nearly horizontal.
Among the lighting requirements, particularly those for visual tasks, especially papers on the desk and a human face are studied. Particularly requirements for the human face are important and as follows:
(1) Prevention of the silhouette effect of the human face in front of the lateral window.
(2) Improvement of the modelling of the human face near the window.
These are studied and combined requirements for the suitable integration of electric light and daylight are lead.
An example of measured illuminance distribution in the unilaterally lit office and the evaluation of this for the above requirements are shown.

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In order to ask the subjects to answer their preference among environmental stimuli, and to estimate the extent of their own sensitiveness to intense or weak sensory stimuli, the two checklists were compiled. Using these lists, the two researches conducted.
Research 1: By the Varimax method of the factor analysis, the 8 factors were obtained from the 36 items list with 100 male medical students. The following labeles were given to each of these 8 factors; A) General sensitivity, B) Temporal sensitivity, C) Orientation to the weak stimuli (the 2 factors were contained in this label), D) Orientation to the intense stimuli (the 2 factors were contained in this label), E) Activation level, and F) Abnormal temporal sensitivity. The label C) means the weakness in tolerance for intense stimuli, and the D) meansto to lerate intense stimuli.
Research 2: The 6 factors were obtaind from the 58 items list with 229 male engineering students. The 5 factors of the 6s were named the same as to each of the 5 labeles in the research 1 (A to E). The other one was labeled G) sensorymotor reactivity. There is no abnormal sensitivity F).
Discussion: The 4 properties, labeled A to D, were the sensory properties common to large samples of subjects. The other three were the depending properties on the individual differences in subjects. Since no factor correlations were in all factor combinations statistically, the common properties were inter independently. Thus we analogize that is not always necessary for the non-sensitive subjects to like the intense sensory stimuli, and not always necessary for the sensitive subjects to prefer the weak stimuli in environments.

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