BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the controlling of the execution of a watering program by an irrigation controller.

2. Discussion of the Related Art

Rain sensors for use in the interruption of programmed watering schedules of an irrigation controller are generally known to include a material that is responsive to rain, and in the event a preset level of rain is exceeded, a switch is activated which outputs a signal to the irrigation controller that causes the controller to cease the execution of watering schedules.

U.S. Pat. No. 6,452,499 to Runge et al. (which is incorporated herein by reference) describes a wireless rain sensor that uses a hygroscopic material that expands when exposed to water. When the hygroscopic material expands beyond a specified point or threshold, an integrated transmitter wirelessly transmits a radio frequency signal to a receiver attached to the controller. The receiver receives the wireless signal and causes the controller to cease watering. Similarly, U.S. Pat. No. 6,977,351 to Woytowitz (which is incorporated herein by reference) describes a wireless rain sensor including a hygroscopic material that is not mechanically connected to the switch that triggers the transmission of the wireless signal that will cause the interruption of watering The threshold level may be adjusted by a user through the mechanical adjustment of the distance the hygroscopic material must expand before actuating the switch, such as described in U.S. Pat. No. 6,570,109 to Klinefelter et al (which is incorporated herein by reference). Thus, in order to exceed a selectable threshold, the hygroscopic material must expand a selectable distance, which corresponds to a selectable level of rain fall.

SUMMARY OF THE INVENTION

Several embodiments of the invention provide methods and apparatus for sensing rain fall for use in irrigation control.

In one embodiment, the invention may be characterized as a rain sensor comprising: a moisture absorptive material adapted to move in response to rain fall; a plunger adapted to move in response to and proportional to the movement of the moisture absorptive material; and a sensor element. The sensor element comprises a first element and a second element coupled to the plunger and adapted to move with the plunger relative to the first element causing a change in a variable corresponding to the amount of rain. The rain sensor also comprises a controller adapted to measure the variable and further adapted to generate a signal comprising an indication of the amount of rain fall based on the variable.

In another embodiment, a wireless rain sensor comprises a housing at least partially covering a first sensor, a controller and a wireless transmitter. The first sensor comprises a moisture absorptive material located to be contacted by rain fall and configured to expand in response to the contact with the rain fall and contract in response to an absence of the rain fall. The controller is coupled to the first sensor and configured to output signals corresponding to a variable amount of expansion and contraction of the moisture absorptive material. The wireless transmitter is configured to transmit wireless signals, at least one wireless signal comprising data corresponding to the variable amount of expansion and contraction of the moisture absorptive material.

In another embodiment, a method of sensing rain fall comprises: sensing, with a first sensor, a variable amount of expansion and contraction of a moisture absorptive material located to be contacted by rain fall, the moisture absorptive material configured to expand in response to contact with the rain fall and contract in response to an absence of the rain fall; outputting, with a controller, signaling corresponding to the variable amount of the expansion and contraction of the moisture absorptive material; and transmitting wireless signals with a wireless transmitter, at least one wireless signal comprising data corresponding to the variable amount of expansion and contraction of the moisture absorptive material, wherein the first sensor, the controller and the wireless transmitter are at least partially covered by a housing

In another embodiment, a wireless rain sensor comprises a housing at least partially covering a first sensor, a controller and a wireless transmitter. The first sensor comprises: a moisture absorptive material located to be contacted by rain fall and configured to expand in response to the contact with the rain fall and contract in response to an absence of the rain fall; and a component coupled to a first portion of the moisture absorptive material and configured to move with the expansion and contraction of the moisture absorptive material. The controller is coupled to the first sensor and configured to output signals corresponding to a variable amount of expansion and contraction of the moisture absorptive material. The wireless transmitter is configured to transmit wireless signals independent of a rain fall threshold, at least one wireless signal comprising data corresponding to the variable amount of expansion and contraction of the moisture absorptive material, wherein the rain fall threshold is not set at the wireless rain sensor.

