Digital Sundial

Hines Digital Sundial




US Patent 4,782,472


Recognized by the North American Sundial Society as

“The first true digital sundial”


     The world’s very first digital sundial was invented by Steve Hines in 1984, and patented in 1988, and shows the time with a true 7-segment digital display.  The sun shines through slits in the encoder, onto the ends of optical fibers, that route the light to the segments in the numerical display.


     So-called “shadow-mask sundials” appeared 10 yrs. later. and have a limited time range of 3-4 hrs., display in 20-minute increments, and do not use actual 7-segment numerals.  


What is a 7-Segment Display?


     A 7-segment display is made of seven lines to form a readable  number.   In the past, all 7-segment displays have been elegiacal.  Tjhi is the world’s first optical analog-to-igital display.

     In the digital sundial, optical fibers from the encoder are clear epoxied to the backs of the seven Plexiglas segments in the display.  The display segments are ieocy.con one optical fiber glued to the back.









      Optical fibers are shown epoxied in holes in the clear Plexiglas encoding cylinder (combining the functions of a rotary encoder and the gnomon of analog sundials). The opposite ends of the fibers are attached to segments, of 7-segment numerical, with clear epoxy.  Depending on the position of the sun, various optical fibers are illuminated to form readable numbers.  


End view of the cylinder:

      Sunlight shines through slits in the cylinder,  As the sun moves across the sky.  The opposite end of the fiber illuminates a segment of the display to form a readable number.  



The four categories of timekeeping devices:

     All timekeeping devices fall into four categories: analog or digital clocks, or analog or digital sundials.  The digital-sundial category has gone without an example until the Hines digital sundial, invented in 1984 and recognized by the North American Sundial Society as the “First True Digital Sundial”.  




     The sundial in an interactive museum:


      The digital sundial shown in a museum setting where a visitor can rotate a “sun” around a globe, to sequence the overhead “sunlight”.  Sunlight shines through slits in the encoder to illuminates various optical fibers which illuminate segments of the numerals in the display.





Advantages of the Hines digital sundial over other other sundials: 

  • It provides the time at a glance.
  • The display can be routed inside an air conditioned house, classroom or museum.
  • The display being at almost any distance from the encoding cylinder at the far end of a fiber-optic bundle.  
  • The 7-hour time range, from 9 AM to 4 PM, in 10-min. increments.
  • The educational value of being the world’s first optical A-to-D converter.  
  • Not having to position the encoding cylinder at eye level.  The ability to have the encoding cylinder in an out-of-the-way location, on a roof, etc. and less likely to encounter the shadows of trees or malicious damage.    



Advantage of the Hines digital sundial over other timekeeping devices of any type:

  • Being able to read the time on a 7-segment digital display without dependence on any electrical power. 



Sundial Resources:




How it works:

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









A single opening in the top of the cylindrical encoder allows light to illuminate 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 shining 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 (PDF format) to build one 4″-diameter cylinder digital sundial are available for $200.  Please send an email or text message if you send payment, to avoid a delay in our providing the drawings.

    • Steve Hines
    • HinesLab, LLC
    • email for the physical mailing address in Virginia, USA



YouTube video



  • Your work is fascinating, and the sundial is an intriguing combination of components and engineering”  Dr. Carlene Stephens, Curator, Smithsonian Museum, Dec. 19, 2023
  • Hines digital sundial, recognized by the North American Sundial Society as “The First True Digital Sundial“.  Oct. 2, 2014
  • U.S. Patent 4,782,472, issued to S. Hines, November 1, 1988



  • plans ordered by Rick Steenblik, September 18, 1985
  • U.S. Patent 4,782,472, issued to S. Hines, November 1, 1988
  • Solar Today Magazine, August 20, 1994 issue, p. 39
  • plans ordered bt Phillip Rogen, September 6, 1994
  • plans ordered by Robert McGrath, September 10, 1994
  • plans ordered by William Georgian, September 27, 1994
  • plans ordered by Robert Siebert, Nov. 1, 1994
  • plans ordered by William Georgian, September 23, 1994
  • plans ordered by James Luttrell, January 21, 1995
  • plans ordered by Hans Sassenburg, May 1, 1999
  • information requested by Sundials magazine, November 29, 2001
  • plans ordered by Till Liepmann, April 1, 2002
  • incorporated in paper presented by Bob Kellogg, at the North American Sundial Society conference in Banff, Alberta, Canada, August 21-24, 2003
  • plans ordered by Charles Ashcroft, Sept. 7, 2007
  • plans ordered by Punjab Engineering College, India, February 6, 2008
  • plans ordered by Bret Niemeyer, June 28, 2011
  • plans ordered by Pat O’Grady, Sept. 4, 2014
  • North American Sundial Society (NASS) declares it “The First True Digital Sundial“, October 2, 2014
  • plans ordered by Edgar Kogler, April 24, 2018
  • Great design“, Jean-Baptiste Rouquier, Dec. 27, 2022



Hines’ original lab notebook #1 entries for this invention.  

p. 38 p. 39





Virginia, USA





ph. 818-507-5812