Filter for partially transmitting light

#This invention relates to a filter made of prisms and which partially transmits or shields light.

#Conventional transparent glass plates transmit light through the entire surface thereof. Therefore, when it is employed as a front window or a windshield of a car, the driver is often dazzled by the light of an oncoming car. Furthermore, when it is employed as a plate glass front of a display case which faces the sun-shining outside street, the sun beams are transmitted through the window and fade the articles on display resulting in the deterioration of the commercial value of the articles.

#It is an object of the present invention to provide a prism-made filter which can resolve the aforementioned problems which have afflicted conventional glass elements.

#FIG. 1 is a side view of a filter of this invention wherein the basic structure of the filter is shown.

#FIG. 2 is an explanatory view showing the filter of this invention applied to a glass front of a display case.

#FIG. 3A and FIG. 3B are explanatory views showing the filter in different inclined positions relative to the position of eye.

#The filter of this invention is described in detail in conjunction with the attached drawings.

#In FIG. 1, the principle construction of the filter of this invention is described wherein parts of right-angled prisms 1 have their inclined surfaces abutting with each other forming a filter unit 2 such that the incident light which has an angle of incidence of more than a critical angle is all reflected by the inclined abutting faces of the units 2. To obtain the desired reflection of the incoming light by the inclined surface, a thin air layer must be formed between the inclined surfaces of the prisms 1. Or a past which has very weak reflection rate may be provided between the inclined surfaces.

#These units 2 are stacked and secured with each other forming an elongated flat plate while a shield plate 3 which prevents the direct light from transmitting from one unit 2 to the next unit 2 is provided between each two units 2.