A new continuous-feed facsimile scanner

Abstract

typical s c a n n e r used in facsimile transmission h a s b e e n of w h a t m a y b e called t h e " l a t h e " t y p e . I n s u c h scanners t h e subject c o p y , whose g r a p h i c c o n t e n t is g e n erally to b e delivered elec trically to a d i s t a n t r e c o r d i n g p o i n t , is w r a p p e d a r o u n d a n d s o m e h o w fastened to t h e surface of a c y l i n d r i c a l d r u m .T h e c o p y -c a r r y i n g d r u m t h e n is r o t a t e d a n d , b y m e a n s of a track a n d lead-screw, a p h o t o e l e c t r i c " t o o l " is m o v e d axially a l o n g t h e r o t a t i n g c y l i n d e r so as to t r a c e a h e l i c a l p a t h over t h e w h o l e c o p y surface. Successive t u r n s of t h e helix so t r a c e d c o n s t i t u t e t h e successive s c a n n e d lines of t h e i m a g e to b e t r a n s m i t t e d . T h e m e c h a n i c a l o p e r a t i o n is a n a l o g o u s to t h a t of a s c r e w -c u t t i n g l a t h e , a n d t h e design p r o b l e m s a n d limitations a r e q u i t e similar. S u c h a design h a s c e r t a i n i n h e r e n t o p e r a t i n g l i m i t a t i o n s , in t h a t (a) after e a c h transmission (except for " r e p e a t s " ) t h e old subject c o p y m u s t b e r e m o v e d from t h e d r u m a n d n e w c o p y w r a p p e d a r o u n d a n d fastened to it, a n d (b) t h e subject m a t e r i a l m u s t b e in t h e form of t h i n flexible single sheets, so t h a t t h e p a g e s of a b o u n d b o o k or m a g a z i n e a r e diflicult to h a n d l e unless t h e b i n d i n g is d e s t r o y e d . M o r e recently t h e r e h a v e b e e n a n u m b e r of a t t e m p t s , b y t h e a u t h o r s ' l a b o r a t o r i e s as well as b y o t h e r s , to design facsimile s c a n n e r s t h a t w o u l d b e m o r e versatile for v a r i o u s a p p l i c a t i o n s , a n d w o u l d n o t h a v e t h e o p e r a t i n g l i m i t a t i o n s j u s t e n u m e r a t e d . N o t a b l e a m o n g these n e w e r designs a r e t h e s c a n n e r s devised b y C h a r l e s J. Y o u n g a n d his associates erf R a d i o C o r p o r a t i o n of A m e r i c a L a b o r a t o r i e s , I n c . , in w h i c h a b r i g h t spot of light is d e v e l o p e d u p o n t h e screen of a c a t h o d e -r a y t u b e , s w e p t in a s t r a i g h t line across t h e screen, a n d p r o j e c t e d u p o n t h e subject c o p y to p r o v i d e fast or side-to-side s c a n n i n g . Slow, or e n d -t oe n d , s c a n n i n g is o b t a i n e d b y c o n t i n u o u s l y a n d progressively m o v i n g t h e c o p y itself. T h u s t h e old d r u m a n d l e a d -s c r e w a r e e l i m i n a t e d a n d t h e e q u i p m e n t is e n a b l e d to h a n d l e c o p y t h a t is in b o u n d form or w h i c h is l o n g e r t h a n w o u l d be feasible for d r u m -m o u n t i n g . O t h e r suggestions h a v e involved t h e p r o d u c t i o n of a m o v i n g light spot b y i l l u m i n a t i n g or o b s e r v ...

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“…Limitations imposed by the necessity for wrapping and attaching the material to the drum have led to recent developments i n flat scanners. Western Union's Intrafax equipment, (10) the new Hogan Labs scanner, (11) and, in Europe, the Philips high-speed facsimile system, (12) carry the material to be scanned past a slot, the length of which is scanned repeatedly by the photocell. (Figure 3.…”