Davis Instruments Corporation

Richard C Anderson

Robert C Jameson

Cone and debris screen for a rain gauge

A sensor housing and cosine diffuser are provided for the detection and measurement of ultraviolet (UV) irradiance. The cosine diffuser has a tiered structure to efficiently receive and transmit incident light that passes over and/or through the sensor housing structure. The sensor housing structure can be configured to have an irregular, serrated, castellated, and or repeating prong and/or tooth sequence to form a cutoff comb, through which incident light is attenuated. The attenuation of light in turn reduces measurement error caused when too much or too little incident light, relative to the actual intensity and irradiance of ambient incident light, reaches and transmits through a cosine diffuser due to the variation of the zenith angle of incident light over the course of a day.

UV irradiance sensor with improved cosine response

A cylindrical housing is provided with outside protecting louvers and central cylindrical aspirated flow paths. First, the surrounding louvers are circular and slope downward at their cylindrical inner and outer edges so as to deflect radiation outwardly of the shield and permit cooling by ambient wind. Second, these surrounding louvers along the upper surface are each provided with vertical convection flow apertures to permit natural convection currents. Third, the housing and the louvers are given a small spatial separation to prevent heat conduction. Fourth, a motor driven fan is placed at the top of the central cylindrical flow path. Air is drawn from the bottom of the housing at a screen-guarded circular opening. Air then passes around an aerodynamically shaped radiation baffle into the sensor chamber of the shield. Fifth, air drawn between the walls of the protecting housing is drawn along at least two flow paths. A first flow path travels along the length of the inside surface of the outer wall of the housing. A second cylindrical-shaped stream of traveling air provides cooling to the wall immediately surrounding the measuring sensor. Finally, a solar powered fan motor and battery circuit is provided with a resistor in series with the battery. The fan motor powering circuit enables increased aspiration during direct sunlight hours, limits solar cell charging current to the during sunlight hours, and finally reduces discharge current during non sunlight hours to prolong battery driven fan operation. Maximum accuracy of temperature and humidity measurement is enabled.

Growing community of inventors

San Jose, CA, United States of America

Richard C Anderson