PICTURES BY TELEPHONE

Auckland Star, Volume LV, Issue 170, 19 July 1924, Page 17

PICTURES BY TELEPHONE

Tbe process demonstrated above is best" described by the company in its statement announcing that the perfected invention is ready, should demand develop, for installation at their long distance stations for public use. The statement ■ "The film upon which a picture has been transferred is inserted in the transmitter simply by rolling; it up in a cylindrical form. During operation a very small and intense beam of light shines through the film on to a photoelectric cell within. The film is rotated at a uniform speed, and by means of a screw mechanism is caused to advance parallel to the axis of the cylinder. The motion of:the light relative to the cylinder ii therefor*

the same as-that of a phonograph needle relative to a cylindrical record. In this way each minute portion', of the picture in turn affects the intensity of the- light' reaching the photoelectric cell. This variation in the amount of light striking the sensitive,*' surface: of the cell gives rise to a current which, through the agency of a vacuum tube amplifier and modulator, controls the current flowing through the telephone line. At the receiving end an unexposed photographic film is rotated under a beam of light in a manner similar to that at the transmitting end. The two films are caused. to rotate at exactly the same speed, and tbe impulses starting from the photoelectric cell at the sending end control, by means of a new device known as a light valve, the amount of light ... reaching the film at the receiving end,"