United. States Patent [191
`Sheriff
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,931,775
`Jun. 5, 1990
`
`[54] PLANT WATERING NEED MONITOR
`[76] Inventor:
`‘168:: wz'isslizlggl? GéSiZEHSZOM
`ym ’
`’
`'
`[21] Appl' No‘: 222’640
`[22] Filed:
`Jul. 21, 1988
`
`Related U.S. Apphcatmn Data
`[63] comm‘mlon'm'pm of Ser’ No‘ 53’7O6’ May 26’ 1987'
`[51] Int. Cl.5 ............................................ .. G088 21/ 00
`[52] US. Cl. .................................. .. 340/604; 340/693;
`73/3365; 324/696; ZOO/61.05
`[58] Field of Search .............. .. 340/604, 693; 343/825;
`324/65 P, 61 P; 73/ 335, 336, 336-1, 338-6, 333,
`304 R; ZOO/61.05
`
`[56]
`
`References Cited
`
`OTHER PUBLICATIONS
`“Water Warbler”, Electronics Australia vol. 37 No. 9 pp.
`42-43; D. Edwards.
`Primary Examiner-Josesph A. Orsino
`Assistant Examiner-J ill Jackson
`Attorney, Agent, or Firm—Henry J. A. Charmasson
`[57]
`ABSTRACI
`An alarm device for monitoring the watering needs of a
`plant which comprises a stick surmounted by a cylindri
`cal box containing the electrical elements. The stick is
`buried in the soil of a pot holding a plant. The alarm
`device is powered by a battery easily installable and
`consists of a conductive probe detector located at the
`buried end of the stick. It also comprises a ?rst inte
`grated circuit which is switched by a backwards con
`nected ampli?er acting as a very high impedance switch
`U.S. PATENT DOCUMENTS
`which minimizes power consumption. The circuit emits
`:1 series of pulses when a threshold resistance level is
`3,927,370 12/1975 De Bough ......................... .. 340/693
`3,961,247 6/1976 Toki ........ ..
`324/65 R reached. These pulses trigger a melody integrated cir
`3,968,428 7/ 1976 Numoto .......... ..
`324/65 P
`cuit which produces a pleasant singing melody destined
`4,020,417 4/1977 Brehob et a1
`324/65 R to draw the attention of the plant grower to the water
`gaff‘beck
`ing needs of a plant. The tune is repeatedly reproduced
`"73/304 c
`4’350’040 9/1932 F
`until the soil resistance detected by the probe detector
`73/3365
`43031707 3/1985 Rosa et al.
`has exceeded ‘1 threslmld resistance level
`4,s14,722 4/1985 Batcheler et al. ......... .. 340/604
`4,621,229 11/1986 Hirth ............................... .. 324/65 R
`
`14 Claims, 2 Drawing Sheets
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`FITBIT EXHIBIT 1020
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`US. Patent Ju1‘r1.5,1990
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`Sheet 1 of2
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`PLANT WATERING NEED MONITOR
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`PRIOR APPLICATION
`This is a continuation-in-part of application Ser. No.:
`07/053,706 ?led 5/26/87 which is now abandoned.
`
`FIELD OF THE INVENTION
`This invention relates to soil moisture detectors, more
`speci?cally to an alarm device for monitoring the wa
`tering needs of a plant.
`
`10
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`4,931,775
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`ble alarms of industrial grade equipment also may not be
`appropriate for the home environment.
`None of the prior art the applicant is aware of incor
`porates a monitoring circuit that draws less than 5 mi
`croamps or provides a pleasant indicator of watering
`needs. The prior art current drain results in the need for
`sophisticated sampling circuits or space consuming
`larger batteries in order to obtain a battery life in excess
`of one year.
`
`20~
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`15
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`BACKGROUND OF THE INVENTION
`Moisture sensors are increasingly found in regulating
`devices, in particular in air moisteners. They have also
`been used in soil moisture regulation, more speci?cally
`in greenhouses where the air and the soil must be simul
`taneously maintained at fixed levels of moisture. Gener
`ally, the moisture sensors found in industrial green
`houses are sophisticated and expensive devices'moni
`tored by computers or full time operators in connection
`with watering devices or humidi?ers. These devices are
`activated when the moisture level falls below a prede
`termined level by means of appropriate alarms and/or
`software. Other types of industrial monitoring unrelated
`to plant watering needsare also sophisticated devices,
`such as U.S. Pat. No. 4,350,040.
`Some prior art also exists for monitoring the watering
`needs of house plants. These devices measure soil impe
`dance changes across probes placed proximate to the
`plant. As soil moisture changes, the impedance changes
`until a set point is reached and an indicator signals the
`need for watering, as shown in U.S. Pat. No. 4,020,417.
`Some of these monitors are related to or have been
`developed from the sophisticated devices used in indus
`trial applications. These sophisticated devices may pro
`vide a means to precisely and linearly calibrate the
`device (such as taught by U.S. Pat. No. 4,621,229) and
`/ or include precise temperature compensators (such as
`disclosed in U.S. Pat. No. 3,961,247). Also as a carry
`over from the industrial grade equipment, an audible
`alarm is also used an an indicator of watering needs.
`In contrast to the precision, availability of power,
`operators and automatic devices in an industrial applica
`tion, house plant monitoring devices are typically bat
`tery powered, precision and temperature compensation
`is unnecessary and full time operators are not present.
`Battery life is a key consideration in the in-home appli
`cation. Although, the majority of the time, the current
`drain on the battery is expected to be caused by the
`monitoring of the soil probes, the current draw of the
`watering need indicating means must also be limited to
`prolong battery life since the house may be empty for
`extended periods.
`The need for extended battery life in these in-home
`applications has lead to sophisticated sampling and
`monitoring circuits to minimize the monitoring drain on
`the battery, such as taught in U.S. Pat. No. 4,514,722.
`60
`‘LED indicators, piezoelectric ceramic beepers, and DC
`to DC converters are also employed to minimize cur
`rent draw (U.S. Pat. No. 4,514,722). These approaches
`have increased battery life, but have resulted in a so- ,
`phisticated device.
`65
`What is needed is a small, low cost, in-home monitor
`of 'soil moisture, not an adaptation of industrial grade
`equipment. The power requirements and irritating audi
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`SUMMARY OF THE INVENTION
`The principal and secondary objects of the invention
`are:
`to provide a simple long lasting in-home alarm device
`for monitoring the watering needs of a plant;
`to provide a compact stick like device to be buried in
`the soil; and
`to provide an alarm device which draws attention of
`the plant grower by producing a pleasant melody
`whenever the moisture of the soil containing plant
`has fallen below a predetermined threshold. These
`and other objects are achieved by an alarm device
`in the form of a stick surmounted by a cylindrical
`box containing the electrical elements. The stick is
`buried in the soil of a pot containing a plant. The
`alarm device is powered by a battery easily install
`able and consists of a conductive probe detector,
`located at the tip of the stick to be covered by the
`soil. It also comprises a ?rst integrated monitoring
`circuit which is fed by an ampli?er connected as a
`very high impedance switch, which drastically
`minimizes current drain on the battery. The inte
`grated circuit emits a series of pulses when a
`threshold resistance level is reached and the ampli
`?er allows signi?cant current to be drawn. These
`pulses trigger a melody designed to pleasantly
`draw the attention of the plant grower to the wa
`tering needs of a plant. The tune is repeatedly re
`produced until the soil resistance detected by the
`probe detector has exceeded a threshold resistance
`level.
`
`BRIEF DESCRIPTION OFTHE DRAWINGS
`FIG. 1 illustrates one preferred embodiment of the
`present invention;
`FIG. 2 shows a block diagram schematic of a circuit
`made in accordance with the preferred embodiment
`illustrated in FIG. 1;
`‘
`FIG. 3 shows exemplary circuitry for the preferred
`embodiment illustrated in FIG. 1; and
`FIG. 4 shows a typical current drain during a water
`ing cycle.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`FIG. 1 shows the preferred embodiment of the pres
`ent invention. The alarm device 1 consists of a stick 2,
`typically of length between 5.0 and 15.0 centimeters,
`terminated in a wire 3. The stick 2 typically takes the
`form of a metallic barrel surrounding the wire 3 on
`almost all its length. The stick 2 and the wire 3 insulated
`inside the stick 2 are electrical conductors, preferably
`made of stainless steel. They constitute the two elec
`trodes of a conductive moisture sensor or probe 7. A
`plastic cap 4 insulates the two electrodes at the extrem
`ity of the stick 2.
`The stick 2 is surmounted by a cylindrical box 6
`which contains the electrical elements. The box 4, pref
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`erably made of plastic, includes a lid 5 which can be
`con?guration provides a great stability in the circuit
`removed for the installation of a new battery. In opera
`and create a very high input impedance. The backward
`tion, the stick 2 is planted into the soil contained in the
`wiring of the FET switch results in a very low current
`plant pot on all its length. The cylindrical box 5 rises
`draw. In the preferred embodiment of the present in
`above the surface of the soil and can be inconspicuously
`vention, the level ampli?er 9 is preferably a 2N5485.
`hidden in the foilage of the plant.
`The trigger 10 of FIG. 2 consists of the Reset func
`Referring now to FIG. 2, there is illustrated a block
`tion port or pin 12 of an integrated circuit 17. The resis
`diagram schematic of a circuit made in accordance with
`tance threshold detected by the variable resistor 8 and
`the preferred embodiment of the present invention. The
`the level ampli?er 9 activates the port P12 of the inte
`probe 7 serves as the invention’s input signal. The probe
`grated circuit 17, thereby activating the oscillator 11. If
`7 consists of a humidity sensor. Several humidity sen
`the resistance is less than the threshold resistance level,
`sors are already known. In the preferred embodiment, a
`the current ?ows back into the circuit through a resistor
`resistance sensor (2,3) is used. It typically consists of the
`R4, typically of 10 megohms. The intensity of the cur
`metallic barrel 2 and of the wire 3, as shown in FIG. 1.
`rent is typically of 2 microamperes. The entire system is
`The length and spacing of the electrodes determine the
`then in a dormant stage. If the resistance level is greater
`resistance threshold necessary to trigger a resistance
`than the threshold resistance level, the oscillator 11
`level. It should, however, be understood that any other
`starts to oscillate. It consists of two resistors R5 and R6,
`moisture sensor such as a capacitance moisture sensor,
`typically of respective values 120 kilohms and 1.5 me
`would. be suitablefor the present invention. The con
`gaohms, as well as of a capacitor C2. The resistors R5,
`ductivity of the soil between the two electrodes varies
`R6 and the capacitor C2, typically of capacitance 0.1
`with the degree of moisture as well as with other factors
`microfarad, are respectively connected to the ports P9,
`such as the mineral content of the soil. When the water
`P10 and P11 of the integrated circuit 17. The frequency
`is consumed or evaporates, the soil dries out, causing
`of the oscillator 11 is determined by the values R5, R6
`the conductivity of the material between the electrodes
`and C2. The input impedance of the reset pin P12 is
`to decrease. Since the amount of watering varies with
`lowered once the trigger 10 has been activated. In this
`each plant, the preferred embodiment of the invention is
`manner, a subsequent lower level signal does not affect
`provided with the variable resistor control 8. This vari
`the unit activation process and maintains the operation
`able resistor control 8 is accessible to the user and can
`in progress. The hysteresis circuit is built within the
`be calibrated in accordance with the amount of water
`trigger 10 so as to prevent false or multiple signals from
`required for a particular plant. The input signal mea
`interfering with a previous triggering threshold signal
`sured between the electrode of the probe 7 and con
`level.
`trolled by the variable resistor 8 is subsequently ampli
`A divider built within the integrated circuit 17 re
`?ed by a level ampli?er 9. The level ampli?er 9 is con
`duces by binary division the frequency of the oscillator
`nected and constructed so that the input and output
`pulses. Preferably, the frequency of the pulses amounts
`signal constantly remain in phase.
`to approximately 5-6 minutes over a wide spectrum of
`If the output level of the level ampli?er 9 falls below
`temperatures. The integrated circuit 17 is typically a ‘
`a threshold value, the trigger 10 is activated causing the
`4060 IC chip.
`oscillator 11 to oscillate. A divider 12 reduces the fre
`The positive pulse generated by the integrated circuit
`quency of the oscillator pulses. The rising edge of a
`17 and the divider 12 every 5-6 minutes flows from the
`positive pulse originating from the divider 12 activates
`port P3 of the integrated circuit 17 into a triggering port
`another trigger 13, allowing a melody chip 14 to cycle
`13 of the melody chip 14, typically on integrated circuit,
`once through a predetermined tune. After one pulse has
`via a capacitor C3, typically of value 1 microfarad.
`activated a trigger 13 and thereby the melody chip 14,
`When the trigger 13 is activated by the rising edge of a
`the tune is repeatedly reproduced until the probe signal
`positive pulse, the melody portion of the same inte
`changes and exceeds the threshold level. Such change
`normally occurs when the plant is being watered again.
`grated circuit 14 is caused to cycle once through the
`predetermined tune. The melody integrated circuit 14
`In order for the melody chip signal to be audible in
`consists of etched semi-conductors which repeatedly
`normal conditions, a low power audio ampli?er 15 am
`pli?es the audio signal originating from the memory
`produce the same tune once the pulse originating from
`chip 14 and transmits it to a speaker 16.
`the divider 12 has activated the trigger 13. The tune
`50
`selected in the preferred embodiment of the present
`Referring now to FIG. 3, there is shown exemplary
`circuitry of all the elements shown in FIG. 2. The cur
`invention was the following tune: “Love Me Tender”.
`rent flowing through the electrodes of the probe 7 is
`It should be understood that any other appropriated
`tune would be suitable.
`passed across a resistance R1 and directed to the vari
`able resistor 8. The resistance value of R1 is typically
`The integrated circuit 14 is preferably a melody IC
`100 Kilohms. The variable resistor is grounded via a
`chip, such as UM 3166-11 H. The integrated circuit 14
`resistor R2, typically of value of l megaohm. The vari
`is further connected to a speaker 16, as previously de
`able resistor 8 can vary between 0 ohm and 1 megohm.
`scribed, via an audio ampli?er not represented in FIG.
`The current then flows into a level ampli?er 9 across
`3. the device is electrically supplied by a battery 18. In
`a resistor R3, of 1 megohm in the preferred embodiment
`the preferred embodiment, no more than three 1.5 volt,
`60
`of the present invention. The level ampli?er 9 is typi
`100 microampere-hour calculator type battery cells are
`cally an FET switch. Preferably, the level ampli?er is
`used for the battery power 18. If reduced battery life (or
`realized in the following con?guration. The gate termi
`less frequent watering signals) is assumed, two 1.5 volt,
`nal G is grounded, the drain terminal D is connected to
`100 microampere-hour calculator battery mercury or
`the voltage source through a load resistor R4 whereas
`silver oxide type cells are acceptable in the preferred
`source terminal S is connected to the signal input resis
`embodiment. In the preferred embodiment, the unit is
`tor R3 and to a ?ltering capacitor C1 of capacitance 0.1
`self testing as soon as the battery is installed, since in?
`microfarad. The capacitor C1 is also grounded. Such a
`nite or air gap resistance will trigger melody.
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`An alternate con?guration to allow shipment with
`a ?rst semi-conductor switch having a drain terminal,
`the battery installed would include a non-conductive
`a gate terminal and a source terminal, said drain
`disposable plastic insulator placed at the battery contact
`terminal being connected to a voltage source
`through a load resistor, said gate terminal being
`points preventing power from activating the electrical
`connected to a signal reference ground, and said
`circuits. Removal of plastic tab insert provides a simple
`source terminal being connected to said electrical
`method of activating and testing (in air) the unit without
`signal through a high value series resistor;
`the need for added switches or circuitry.
`oscillating means for sending electrical pulses at a
`FIG. 4 shows the values of the various electrical
`?rst frequency, said oscillating means being con
`current draws the preferred embodiment units have
`nected to said drain terminal and being triggered
`been set so as to meet the following technical speci?ca
`when the voltage differential between said signal
`tions. When the probe 7 (see FIG. 1) is directly shorted
`and said voltage source causes a certain current
`(regardless of the position of the‘ sensitivity control
`?ow across said ?rst semi-conductor switch and
`setting variable resistor 8 shown in FIG. 2) or threshold
`said load resistor; and
`resistance is not present, the current ?owing in the
`audio~means responsive to said oscillating means for
`alarm circuit is typically less than 2 microamperes (dor
`generating an audio-signal.
`mant condition). When the unit has been activated and
`2. The device of claim 1, wherein said supporting
`before the melody is being played, the current is typi
`means has the form of a stick.
`cally less than 30 microamperes (activated). While the
`3. The device of claim 1, wherein said semi-conduc
`melody is‘playing, the current rate is typically less than
`tor switch is a ?eld effect transistor.
`1000 microamperes. Watering returns the unit to the
`4. The device of claim 1, wherein said means for
`dormant state.
`sensing comprises a ?rst and second electrode, said ?rst
`Considering that the melody is playing for an average
`electrode surrounding said second electrode almost
`of two hours after the unit has been activated and that
`entirely and serving as said supporting means.
`the alarm unit of the preferred invention is normally
`5. The device of claim 4, wherein said electrical si
`triggered twice a week, it is expected that the battery
`ganl is a function of the resistance between said elec
`lifetime is generally eighteen months.
`trodes.
`6. The device of claim 4, wherein said electrical sig
`The probe resistance levels are determined by the
`various resistors and capacitors of the alarm circuit of
`nal is a function of the capacitance between said elec
`trodes.
`30
`the preferred embodiment in order to meet the follow
`7. The device of claim 1, wherein said electrical de
`ing requirements. The threshold resistance level above
`vice is powered by a battery.
`which the unit is activated is typically set to 200 to 300
`8. The device of claim 7, wherein said battery com
`kilohms when the center arm of the variable resistor 8 is
`prises no more than three 15 volt, 100 microampere
`adjacent to the resistor R2. When the center arm of
`hour cells.
`variable resistor 8 is adjacent to the resistor R1, the
`9. The device of claim 7, wherein said battery com
`threshold level is typically 2 to 3 megohms.
`prises no more than two 1.5 volt, 100 microampere-hour
`Although the previous values have been found to be
`cells.
`particularly suited for the objective hereabove men
`10. The device of claim 1 further comprising:
`tioned, it should be noted that other values can be se
`dividing means for reducing said ?rst frequency of
`lected.
`said electrical pulses and for yielding electrical
`While the preferred embodiment of the invention has
`pulses at a second frequency; and
`been shown and described, changes and modi?cations
`said audio-means being activated by said electrical
`may be made therein within the scope of the appended
`pulses at said second frequency.
`claims without departing from the spirit and scope of
`11. The device of claim 10, wherein said oscillating
`45
`this invention.
`means and said dividing means are built into an inte
`What is claimed is:
`grated chip.
`1. An electrical device operating at low currents for
`12. The device of claim 10, wherein said calibrating
`signaling the watering needs of a plant by monitoring
`means, said ?rst semi-conductor switch, said oscillating
`the moisture level of the soil around said plant compris
`means, said dividing means and said audio-means are
`housed in a cylindrical container surmounting said sup
`mg:
`'
`means for sensing said moisture level by generating
`porting means.
`an electrical signal generally proportional to said
`13. The device of claim 10, wherein said audio-means
`moisture level;
`comprises:
`means for supporting said sensing means, shaped and
`a music synthesizer generating said audio-signal; and
`dimensioned to be planted in said soil;
`second means for amplifying said audio-signal.
`means for calibrating said device in accordance with
`14. The device of claim 13, wherein said music syn
`the amount of water ordinarily needed by said
`thesizer is programmed to generate a popular melody.
`plant;
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