Irrigation signaling device

A device for signaling a predetermined soil moisture condition includes a switching tensiometer that closes a switch when the root water tension reaches a predetermined level; a power source connected to the switching tensiometer; and a signal connected to the switching tensiometer so that when the switching tensiometer closes the switch, power source is connected to the signal operate the signal to indicate that the predetermined soil moisture condition has been reached. The signal preferably includes a spring-loaded flag that operates between a retracted position and an extended signal position; a latch for releasably securing the flag in its retracted position, and an electrically operated release that releases the latch to allow the flag to operate to its extended signal position.

FIELD OF THE INVENTION 
This invention relates to an irrigation signaling device, and in particular 
to a device that signals when a switching tensiometer has reached its set 
point. 
BACKGROUND OF THE INVENTION 
Switching tensiometers, such as that disclosed in U.S. Pat. No. 3,559,062, 
are used to measure the root water tension and operate solenoids in 
irrigation systems to control the delivery of irrigation water. These 
devices, however, do not provide any visible signal when their 
predetermined set point is met, and therefore using such tensiometers to 
monitor soil moisture requires that each tensiometer be visually 
inspected. Traveling to the various tensiometers in a field for this 
visual inspection is tedious and time consuming, and is often sacrificed 
in favor of other tasks. Thus soil moisture is not optimally controlled. 
SUMMARY OF THE INVENTION 
The present invention relates to a signaling device which operates with a 
tensiometer to provide a signal of the soil moisture condition by 
signaling when the tensiometer's set point has been reached. The signal 
can be monitored remotely so the time and effort of the inspecting 
tensiometers can be significantly reduced. The signaling device provides a 
positive and stable proof that the set point has been reached. The 
signaling device is of simple, inexpensive, yet robust construction. It 
has minimal power requirements, so that it has a long and reliable service 
life. 
Generally, the signaling device of the present invention comprises a 
switching tensiometer that closes a switch when the root water tension 
reaches a predetermined level. A power source is connected to the 
switching tensiometer; as is a signal so that when the switching 
tensiometer closes the switch, the power source is connected to the signal 
to indicate that the predetermined soil moisture condition has been 
reached. The signal preferably includes a spring-loaded flag that operates 
between a retracted position and an extended signal position; a latch for 
releasably securing the flag in its retracted position, and an 
electrically operated release that releases the latch to allow the flag to 
operate to its extended signal position. The release preferably includes 
an electric motor for operating the latch. A switch may be provided for 
disconnecting the power source from the electric motor when the flag is in 
its extended signal position in order to conserve power. 
The device is of simple and inexpensive yet robust construction. The flag 
provides a positive signal above the crop canopy that can be remotely 
monitored, dramatically reducing the time required to monitor soil 
condition, and thereby improving the quality and frequency of the 
monitoring, allowing swifter intervention if irrigation is needed. The 
device has minimal power requirements, and thus operates reliably for 
extended periods. These and other features and advantages will be in part 
apparent, and in part pointed hereinafter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of an irrigation signaling device constructed according 
to the principles of this invention is indicated generally as 20 in FIGS. 
1-5. The signaling device 20 is adapted to indicate a predetermined soil 
moisture condition. The signaling device 20 comprises a switching 
tensiometer 22 of the type that closes a switch when the root water 
tension measured by the switching tensiometer reaches a predetermined 
level. The switching tensiometer 22 may be, for example a model R/SR 
tensiometer available from Irrometer Company, Riverside, Calif. The 
signalling device also includes a power supply 24. In this preferred 
embodiment the power supply is a pair of batteries 26 connected in series. 
The signaling device 20 also includes a signal 28. The power supply 24 and 
the signal 28 are connected to the switching tensiometer 22 so that when 
the root water tension measured by the tensiometer reaches a predetermined 
level, the switching tensiometer connects the power source 26 and the 
signal 28 operate the signal to indicate that predetermined soil moisture 
condition has occurred. 
In this first preferred embodiment the signal 28 comprises a flag 30. The 
flag 30 is secured to a rotatable axle 32 so that the flag can operate 
between a retracted position (shown in FIG. 4) and an extended signal 
position (shown in FIGS. 1-3 and 5). The flag 30 is resiliently biased to 
its extended position by a coil spring 34 mounted on a vertically oriented 
panel 36. A wire loop 38 is connected to the axle 32 and the spring 34 
such that the loop rotates with the axle 32 and the flag 30 secured to the 
axle. The loop 38 moves from a cocked position (FIG. 4) when the flag 30 
is in its retracted position to a released position (FIG. 5) when the flag 
is in its extended signal position. A latch 40 is mounted on the panel 36 
to releasably engage the loop 38 in its cocked position and thereby retain 
the flag 30 in its retracted position. A trigger 42, biased with a spring 
43, releases the latch 40 when depressed. An electric motor 44 is mounted 
on the back of the panel 36 and is adapted to operate the trigger 42 to 
release the latch 40. A cord 46 extends from the armature of the motor 44 
through an opening in the panel 36 to the trigger 42, so that when the 
motor turns, the cord winds around the armature and actuates the trigger. 
The electric motor 44 is connected to the switching tensiometer 22 so that 
when the switch on the switching tensiometer closes, the electric motor is 
connected to the power supply 24 causing the electric motor to wind the 
cord 46 and actuate the trigger 42, releasing the latch 40 so that flag 30 
can move under the force of spring 34 to its extended signal position. 
There is preferably a normally open switch 48 on the panel 36 that is 
electrically connected in electric circuit of signaling device. The switch 
48 includes an actuator 50 which, when actuated, temporarily closes the 
switch. The switch 48 is positioned so that the loop 38 actuates the 
actuator 50 to close the switch when the loop is in its cocked position 
corresponding to the flag 30 being in its retracted position. The release 
of the flag 30 is accompanied by the movement of the loop 38, and when the 
loop moves, the actuator 50 of the switch 48 is released, allowing the 
switch to return to its normally open condition. This disconnects the 
motor 44 from the power supply 24 to protect the power supply. 
The signaling device is preferably enclosed in a protective case 54 
comprising a housing 56 with an access plate 58. The axle 32 extends 
through the back wall of the protective case 54 so that flag 30 remains 
outside the case so that it can be seen. 
A second embodiment of a signaling device constructed according to the 
principles of this invention is indicated generally as 100 in FIGS. 7 and 
8. The signaling device 100 is similar in construction to signaling device 
20, and corresponding parts are identified with corresponding reference 
numerals. Like signaling device 20, signaling device 100 is adapted to 
indicate a predetermined soil moisture condition. The signaling device 100 
comprises a switching tensiometer 22 of the type that closes a switch when 
the root water tension measured by the switching tensiometer reaches a 
predetermined level. The switching tensiometer 22 may be, for example a 
model R/SR tensiometer available from Irrometer Company, Riverside, Calif. 
The signaling device 100 also includes a power supply 24. In this 
preferred embodiment the power supply is a pair of batteries 26 connected 
in series. The signaling device 20 also includes a signal 102. The power 
supply 24 and the signal 102 are connected to the switching tensiometer 22 
so that when the root water tension measured by the tensiometer reaches a 
predetermined level, the switching tensiometer connects the power source 
26 and the signal 102 to operate the signal to indicate that the 
predetermined soil moisture condition has occurred. 
In this second preferred embodiment the signal 102 comprises a flag 104. 
The flag 104 is secured to a rotatable axle 106 so that the flag can 
operate between a retracted position (shown in FIG. 7) and an extended 
signal position (shown in FIG. 8). The flag 104 is biased to its extended 
position by a counterweight 108 on the end of the flag 104. There is a pin 
110 on the axle 106. A latch mechanism releasably engages the pin 110 to 
retain the signal flag 104 in its retracted position. This latch mechanism 
comprises a wire loop 112 pivotally mounted on a panel 114, and biased 
with a spring 116. The loop 112 moves from a cocked position (FIG. 7) when 
the flag 30 is in its retracted position to a released position (FIG. 8) 
when the flag is in its extended signal position. A latch 118 is mounted 
on the panel 114 to releasably engage the loop 112 in its cocked position. 
The loop 112 in turn engages the pin 110 on the axle 106 against the panel 
114, thereby retaining the flag 104 in its retracted position. A trigger 
120, biased with a spring 122, releases the latch 118 when depressed. An 
electric motor 124 is mounted on the back of the panel 114 and is adapted 
to operate the trigger 120 to release the latch 118. A cord 126 extends 
from the armature of the motor 124 through an opening in the panel 114 to 
the trigger 120, so that when the motor turns, the cord winds around the 
armature and actuates the trigger. The electric motor 124 is connected to 
the switching tensiometer 22 so that when the switch on the switching 
tensiometer closes, the electric motor 124 is connected to the power 
supply 24 causing the electric motor to wind the cord 126 and actuate the 
trigger 120, releasing the latch 118 so that loop snaps to its released 
position, releasing the pin 110, and allowing the flag 104 to swing to its 
extended signal position. 
There is a latch 130 for engaging the pin 110 when the flag 104 reaches its 
extended signal position so that the flag does not continue to swing. A 
small spring 132 may be secured on the axle 106 to bias the axle to turn 
in the correct direction. 
There is preferably a normally open switch 48 on the panel 114 that is 
electrically connected in electric circuit of signaling device. The switch 
48 includes an actuator 50 which, when actuated, temporarily closes the 
switch. The switch 48 is positioned so that the loop 112 actuates the 
actuator 50 to close the switch when the loop is in its cocked position 
corresponding to the flag 104 being in its retracted position. The release 
of the flag 104 is accompanied by the movement of the loop 112, and when 
the loop moves, the actuator 50 of the switch 48 is released, allowing the 
switch to return to its normally open condition. This disconnects the 
motor 124 from the power supply 24 to protect the power supply. 
The signaling device 100, like signaling device 20, is preferably enclosed 
in a protective case 54 comprising a housing 56 with an access plate 58. 
The axle 106 extends through the back wall of the protective case 54 so 
that flag 104 remains outside the case so that it can be seen. 
OPERATION 
The signal device 20 is installed at a height so that the flag 30 is 
visible above the plant canopy when the flag is in its extended signal 
position. In operation, the signal device is set by moving the flag to its 
retracted position (shown in FIG. 4) and securing it in this position by 
engaging the loop 38 with the latch 40. In this position the loop 38 
engages the actuator 50 on the switch 48, holding the switch in its closed 
position. The access plate 58 is placed on the housing 56 to protect the 
mechanism. When the switching tensiometer 22 measures a root water tension 
corresponding to a predetermined set point, the switching tensiometer 
closes its switch, which closes the electric circuit (which is shown in 
FIG. 6) in the signaling device 20. This electrically connects the power 
supply 24 and the electric motor 44. The armature 45 of the motor 44 
turns, winding the cord 46, which pulls on the trigger 42 to release the 
latch 40. When the latch 40 is released, flag 30 swings under the force of 
the spring 34 to its extended signal position. The loop 38 which moves 
with the flag 30, releases the actuator 50 of the switch 48 opening the 
circuit between the power supply 24 and the motor 44. 
The signal device is easily reset by removing the access plate 58, moving 
the loop 38 back to its cocked position and securing it with the latch 40. 
The access plate 58 is then replaced on the case 56, and the signal device 
20 is again ready to indicate when the root water tension reaches the 
predetermined set point on the switching tensiometer 22. 
The signal device 100 is installed at a height so that the flag 104 is 
visible above the plant canopy when the flag is in its extended signal 
position. In operation, the signal device is set by moving the flag to its 
retracted position (shown in FIG. 7 and securing it in this position by 
securing the pin 110 between the loop and the panel 114, and engaging the 
loop 112 with the latch 130. In this position the loop 112 engages the 
actuator 50 on the switch 48, holding the switch in its closed position. 
The access plate 58 is placed on the housing 56 to protect the mechanism. 
When the switching tensiometer 22 measures a root water tension 
corresponding to a predetermined set point, the switching tensiometer 
closes its switch, which closes the electric circuit (which is shown in 
FIG. 6) in the signaling device 100. This electrically connects the power 
supply 24 and the electric motor 124. The armature 128 of the motor 124 
turns, winding the cord 126, which pulls on the trigger 120 to release the 
latch 118. When the latch 118 is released, the loop 112 snaps to its 
released position, freeing the pin 110, and allowing the flag 104 to swing 
under the force of the counterweight 108 to its extended signal position. 
The loop 112 also releases the actuator 50 of the switch 48 opening the 
circuit between the power supply 24 and the motor 124. 
The signal device is easily reset by removing the access plate 58, moving 
the loop 112 back to its cocked position, securing the pin 110 against the 
panel 114, and securing the loop with the latch 118. The access plate 58 
is then replaced on the case 56, and the signal device 100 is again ready 
to indicate when the root water tension reaches the predetermined set 
point on the switching tensiometer 22.