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Electronic sundial apparatus

  • US 4,387,999 A
  • Filed: 08/25/1981
  • Issued: 06/14/1983
  • Est. Priority Date: 08/25/1981
  • Status: Expired due to Fees
First Claim
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1. An electronic sundial apparatus responsive to changes in the position of the sun in the sky for signaling, on an hourly basis, the passage of time, comprising:

  • a first hemisphere having an elongated, vertically-disposed aperture and a plurality of elongated generally vertically extending diverging apertures disposed in the surface of said hemisphere at predetermined locations thereon, said diverging apertures being configured so as to diverge at the uppermost ends thereof in opposite directions away from said vertically-disposed aperture, said vertically-disposed and diverging apertures having a predetermined location and a predetermined length and shape corresponding to the azimuths and the distance between the maximum and minimum altitudes of the sun in the sky at each hour throughout the year for a predetermined, selected latitude;

    a second hemisphere disposed concentrically within said first hemisphere, said second hemisphere also including an elongated vertically-disposed aperture and a plurality of elongated, generally vertically extending diverging apertures disposed in the surface of said hemisphere at predetermined locations thereon, said diverging apertures being configured so as to diverge at the uppermost ends thereof in opposite directions away from said vertically-disposed aperture, said vertically-disposed and diverging apertures having a predetermined location and a predetermined length and shape corresponding to the azimuths and the distance between the maximum and minimum altitudes of the sun in the sky at each hour throughout the year for a predetermined, selected latitude, said apertures functioning in conjunction with said apertures in said first hemisphere to collimate, once each hour, sunlight and cause said collimated sunlight to pass through the concentric radial center of said hemispheres;

    detector means, disposed at said concentric center of said hemispheres, for detecting the presence of said sunlight collimated by said hemispheres; and

    means, coupled to said detector means, for signaling the detection of collimated sunlight by said detector means.

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