PRODUCTION OF TELEVISION SIGNALS 



567 



this series of articles. At the receiving station this current shape is re- 

 ampHfied, impressed on a direct current, and finally produces an 

 image in the receiving apparatus. 



Fig. 6 — Illustrative receiving apparatus. A neon lamp operated from the picture 

 current illuminates a series of small apertures as they pass across the field of view; 

 the observer sees an image reproduced in the frame. 



A photograph, Fig. 6, shows an illustrative arrangement of the 

 parts in one type of television receiver. An essential part of this 

 type of receiver is a disk similar to the one at the transmitting station 

 and also provided with fifty small apertures arranged in the form 

 of a spiral. The driving motor rotates the disk in exact synchronism 

 with the one at the transmitting station. The observer looks at a 

 small rectangular opening or frame in front of the disk. This frame 

 is of such dimensions that only one aperture can appear in the field 

 of view at a time. As the disk rotates, the apertures pass across the 

 frame one after the other in a series of parallel lines, each displaced 

 a little from the preceding one until in one revolution of the disk the 

 entire field has been covered. Beyond the disk is a special form of 

 neon glow lamp shown in detail by Fig. 7. In this lamp, the cathode 

 is a flat metal plate of a shape and area sufficient to entirely fill the 

 field defined by the frame in front of the disk. The anode of the 

 2,7 



