CAMERON, LARRY;WEINTRAUB, MARVIN H.;BERNIER, DONALD R.
发明人:
CAMERON, LARRY
申请号：
EP19870307749
公开号：
EP0305614(A1)
申请日:
1987.09.02
申请国别(地区):
欧洲专利局
年份:
1989
代理人:
摘要：
An automatic control apparatus (58) and method for sprinkling water over a predetermined area includes a control apparatus (18) having first and second sensors (22, 24) disposed underground within the predetermined area, with the first sensor being disposed in a horizontal orientation immediately below the plant root level and the second sensor being disposed in a horizontal position a predetermined distance between the first and second sensors is selected to provide a measurement of the wilt-point moisture content of the type of soil found within the predetermined area. The first and second sensors are provided to measure the impedance of the soil therebetween, with the impedance being proportional to the moisture content of the soil. The output of the first and second sensors is compared with a predetermined electrical reference value established for the wilt-point moisture content of the type of soil found within the predetermined area. When the moisture content detected by the sensor means is below the wilt-point, a comparator (38) energizes a water control valve (10) connected to a source of water to disperse water over the area until the desired wilt-point moisture content is achieved. In an alternate embodiment, the control apparatus is adapted for use in a multi-zone sprinkler system and includes a timer (66) providing first and second predetermined time periods. During the first time period, the sensors are operative to control the application of water to the predetermined area; while during the second time period, the outputs of the sensors are inhibited to enable water control valve to index to the next zone.
