Light distribution control type Illuminator

#The present invention relates to a light distribution control type illuminator.

#Metal halide lamps, a type of discharge lamp, are light sources that seal a metal halide in an arc tube together with mercury and rare gas, and heat the metal halide at high temperature through electric discharge between electrodes of the arc tube to thereby separate the metal halide into metal atoms and halogen atoms and discharge electricity mainly composed of a spectrum that is obtained by exciting the metal atoms. Metal halide lamps have a well-balanced visible radiation spectrum distribution, which gives them excellent color rendering properties, and are fit for many illumination uses.

#A certain type of metal halide for metal halide lamps partially remains in a liquid state in the coldest spot of the arc tube while the lamp is lit. The temperature of the coldest spot is therefore changed by changing the posture in which the lamp is lit, and the vapor pressure of the metal halide is accordingly changed as well as the lamp voltage and temperature and light color. Similar changes in characteristics occur for metal halides that are completely evaporated while the lamp is lit since the density distribution in the arc tube changes in accordance with the posture of the lit lamp. This is why a lighting posture in which the optimum characteristics are obtained is specified for metal halide lamps. Low pressure sodium lamps, which have extremely high visible light emission efficiency, possess similar characteristics and therefore take a designated posture when lit (see, for example, Non-patent Document 1).

#FIG. 1 is an explanatory diagram of the configuration of a light distribution control device according to an embodiment of the present invention.

#FIG. 2 is an explanatory diagram of the operation of the light distribution control device shown in FIG. 1.

#FIG. 3 is an explanatory diagram of a light diffuser used in an embodiment of the present invention (part 1).

#FIG. 1 is an explanatory diagram of a light distribution control device according to an embodiment of the present invention. The light distribution control device according to this embodiment has, as shown in FIG. 1, a light source 1 for radiating light through electric discharge between opposing electrodes 2 and 4, a casing 3 which houses the light source 1, a reflecting mirror 5 disposed behind the light source 1 inside the casing 3 to reflect a flux of light radiated from the light source 1 and thereby control the angle of the flux of light, a path changing mirror 7 placed in front of the casing 3 to change the path of the flux of light controlled by the reflecting mirror 5, and a path changing mirror container 9 which houses the path changing mirror 7 to keep the path changing mirror 7 in a given posture.

#The components are described in more detail below.

#Employed as the light source 1 is a lamp for which a lighting posture is specified such as a metal halide lamp shown in FIG. 5 or a low pressure sodium lamp. The specified lighting posture is a posture specified, by a lamp maker or the like, for the lamp to take when lit in order to obtain the best possible characteristics of the lamp. A lamp posture is specified with the use of the “lamp axis”, or other reference lines of the lamp in some cases. In this case, a reference line that is employed replaces the “lamp axis”.