Digital Sundial

Digital Sundial



U.S. Pat. 4,782,472

“The first true digital sundial”,  North American Sundial Society


      The Digital Sundial was developed by Steve Hines as an optical analog-to-digital converter and uses no electrical power.  It makes use of the changing position of the sun, shining through slits, to illuminate optical fibers, that illuminate the display that can be placed in a house, office or museum.  



      Individual optical fibers are shown epoxied in holes in the clear Plexiglas encoding cylinder (analogous to the gnomon of other sundials).  The opposite ends of the fibers are attached to individual segments, of a 7-segment numerical display, with clear epoxy.  Depending on the position of the sun, various optical fibers illuminate segments to form the numbers.  

      An end view of the encoder shows the sunlight shining through slits, illuminating the ends of optical fibers as the sun moves across the sky.  When sunlight shines on an optical fiber, the opposite end illuminates a segment of the display to form a readable number.



The four categories of time-keeping devices:


How it works:

      As the sun moves across the sky, sunlight shines through slots in the top of the encoding cylinder and sweeps over the ends of optical fibers in the bottom of the cylinder.  Light travels through the fibers to illuminate the segments of the numerals.  The following animations are without any timing or phase relationship.




A single opening in the top of the cylindrical encoder illuminates two fibers in the bottom of the cylinder, from 10:00 AM to 12:59 PM, to form the “1” which is the tens-of-hours numeral.





In an interval of one hour, a single one-hour-wide band of sunlight sweeps across the ends of fibers to form the units-hours numeral between 9 AM and 4 PM. 







Each hour during the day, light through a different slit sweep over this cluster of optical fibers to repeat the 0-1-2-3-4-5 sequence necessary for the tens-of-minutes numeral.





The limit of accuracy of any sundial is ±2 minutes.  The Digital Sundial reads in the smallest available digital increment above 2 minutes: 10 minutes, with the units-minutes fixed at “0”.


Construction Drawings:

      Construction drawings, sent by email, are available for $200 with a license to manufacture one digital sundial with a 5-inch diameter encoding cylinder, for private non-commercial, non-institutional use.  Please contact HinesLab for a commercial or institutional license for a larger digital sundial.  


YouTube video



Hines’ original lab notebook entries for this invention.

p. 38 p. 39


HinesLab is actively seeking licensees.  To discuss licensing, please contact Steve Hines at:


Glendale, California, USA


ph. 818-507-5812