Abstract: A video signal produced by picking up the light image of light projected upon a screen is quantized by a plurality of voltage comparators grouped in pairs and applied with different reference voltage levels. One of the outputs of comparators of respective pairs is inverted in an orderly manner and then synthesized with the rest of the outputs to produce a dark and bright stripe signal which is displayed on a video display device to form a radially discrete annular pattern representative of equibrightness curves.

Abstract: An ac type line concentrator for use in a data communication system, comprising a crosspoint switch circuit. The crosspoint switch circuit is constituted by a plurality of crosspoint switches capable of switching an analog signal (hereinafter referred to as an analog switch), so that a carrier signal modulated by a data signal may be transferred from one of m incoming lines connected with m terminal units to a selected one of n(n<m) outgoing lines connected with a central unit through the ac type line concentrator without being demodulated.

Abstract: A digital differential analyzer comprises an arithmetic unit for performing an integration operation, a control unit for controlling the arithmetic unit, a plurality of temporary storage means in the arithmetic unit for temporarily storing interim results of the arithmetic operation therein to relieve the influence of propagation delay time of the arithmetic unit.

Abstract: Recognition of the approximate shape of a given article is accomplished by rotating the article by an angle of 180.degree. for thereby producing a direct projection, moving this direct projection perpendicularly onto a reference line for thereby obtaining a perpendicular projection of the article, computing the average pattern-classification value and the range of variation of pattern-classification value from the maximum and minimum ratios of the product of the largest width of the perpendicular projection of that article multiplied by the largest height thereof to the area of the article, and comparing the average pattern-classification value and the variable range with those of the reference pattern.