US 3588038 A
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United States Patent lnventor Tameo Tanaka  References Cited Aura-sun, J p UNITED STATES PATENTS P 7703 2,805,276 9/1957 Weitzel 174/110.44x F1led Oct. 24, 1968 3,314,081 4/1967 Atkms et a1.... 4/100 Patented June 28, 197 l Assi nee K ohm, Gikm Co ud 3,324,647 6/1967 .Iedynak 317/123? 8 max 'k 3,333,160 7/1967 Gorski 251/129x Prior" 25 1967 p 3,406,941 10/1968 lchimori et a1 251/129 y Jap'm 3,422,415 1/1969 lchimori 317/123P 42/68321 Primary ExaminerArnold Rosenthal Attorney-Waters, Roditi, Schwartz & Nissen ABSTRACT: An automatic cock device'comprises a tank circuit capable of oscillation at a frequency of around 40 Mc/S for operation of a cock for a water basin. An electrically cong g Q EP ductive member is positioned adjacent the water basin and is electrically insulated from ground and electrically coupled 11.8. CI 251/129, with the tank circuit. The member is adapted to be influenced 3 l 7/Digest 2, 3 17/ 146, 4/ 100 by the proximity of a hand of a human body thereto to cause a Int. Cl ..F16k 31/02, high frequency loss in the circuit including the member and HOlh 47/00 the hand, thereby causing a variation in the oscillating condi- Field of Search 317/123 tion of the tank circuit to operate a solenoid valve which con- (P); 251/129; 4/100, 166; 174/85, 1 10.44 trols the flow ofwater through the cock.
SHEET 1 [IF 3 PATENTEU JUN28 1971 SHEET 3 OF 3 AUTOMATIC COCK DEVICE The invention relates to an automatic cock device based on the high frequency loss principle, and more particularly to such device for use in a water basin or a wash basin.
When washing hands in a water basin such as is provided in a lavatory or the like, it is the usual practice to open the cock by hand, and the cock is again closed by hand after the released water has been used for washing the hands. While such procedure is very common, this spoils the very purpose of washing, since the cock may be contaminated by contact with unclean hands and subsequently contaminate the cleaned hand. In order to. overcome such difficulty, it has been proposed to open and close the cock by operation of a pedal or other mechanical means. A more convenient arrangement is known in which the cock opens automatically when a hand is placed thereto and closes automatically when the hand is withdrawn. The latter arrangement may comprise a photoelectric system, variable capacitance system, ultrasonic system or high frequency loss system. The photoelectric system has a disadvantage that water flow cannot be interrupted when windows in the light source or acceptor becomes shadowed by splashes of soap water or the like, and involves difficulty in mounting the optical system. The variable capacitance system is susceptible to the influence of water which may remain unremoved adjacent the electrode, because water has a high dielectric constant of nearly 80 and the water residue maintains a high capacitance to prevent or delay the returning operation of the system to stop the water on withdrawing the hand. The ultrasonic system requires a source of ultrasonic wave of large active area in order to have a sharp directivity, and reduction of the source size conditions a substantial increase in frequency, which in turn results in an increased attenuation of the wave in air. Also the system is difficult to mount and adjust.
The high frequency loss system depends for its automatic operation of the cock upon the fact that when an article approaches an electrode'to which high frequency voltage is applied, the apparent h.f. loss in the oscillator circuit increases owing to the influence of the article, thus resulting in an increase in the anode current of the oscillator circuit. This avoids the necessity of windows used in the photoelectric system which are liable to be contaminated. Also, because the system operates on the basis of dielectric loss rather than capacitance, water does not have a dielectric loss comparable to that of a human body, so that it is a simple matter to provide a clear distinction between water and the human body. As compared with the ultrasonic system, the loss system removes the necessity of considering attenuation in air. Thus the h.f. loss system would be most suitable for application as an automatic cock device.
When an article is moved into the vicinity of a conductor charged with a h.f. voltage, an electric charge varying at the same frequency appears by electrostatic induction at a part of the article adjacent the conductor. The charge comprises two components, one by polarization of the article and the other due to an electric current which results from a flow of charge carriers within or on the surface of the article. The human body is considered to be an aqueous electrolytic solution, and the principal factor of the polarization is an ionic polarization and the charge carriers are ions. At a high frequency, current flows very close to the surface owing to the skin effect. When a human body or part thereof is moved toward the h.f. electrode, the polarization causes an increase of capacitance and at the same time, losses are caused by retardation of polarization and mobility of the ions. The net effect of this is equivalent to the connection of a series circuit of a capacitor and a resistor between the electrode and the ground.
Obviously, water exhibits some moment of polarization and retardation of polarization causes a loss. According to the Smithonian Physical Table, pure water has a dielectric constant of7l.5 and tan 8 of 0.059 at 45 C. and at l Mc/S. When frequency is increased to 300 Mc/S, the dielectric constant decreases to 71.0, while tan 6 remains unchanged. As the temperature falls, the dissipation factor decreases and the dielectric constant increases slightly. Water usually available from the water supply contains certain electrolytes so that the dissipation factor will be higher than the values indicated above. In one example, the dissipation factor is of the order of 0.24 at 30 C. and at 40 Mc/S, and is minimum at 40 Mc/S i 5 Mc/S over the frequency range from 5 to 50 Mc/S. Although measurement of the effective value of dissipation factor of a human body involves various difficulties, it has been confirmed in a simple experiment that the human body exhibits a far greater value of dissipation factor at around 40 Mc/S than the supply water.
Then it will be understood that detection, in a manner not influencedby the variation of capacitance, of dielectric loss in an electrode circuit energized at a frequency of around 40 Mc/S will be most advantageous for the recognition of the proximity of a hand to the electrode without adverse influence by the presence of water around the electrode.
While it is not intended that the invention be limited to any particular theory, it is considered that when a hand is proximate an electrode connected with an oscillator circuit, there is added thereto a circuit to the ground through the human body, which causes a substantial dielectric loss. However, it is equally expected that a resistive loss may take part in the total loss, which results in a decreased Q-value of the oscillator circuit. Therefore, the term high frequency loss is intended herein to refer to an inclusive loss covering both dielectric and resistive losses.
The automatic cock device according to the invention comprises a tank circuit capable of oscillation at a frequency of around 40 Mc/S, a cock for a water basin, an electrically conductive member positioned adjacent the water basin, the member being electrically insulated from the ground, means for coupling the member electrically with the tank circuit, and a solenoid valve for allowing or interrupting a flow of water through the cock, said member being adapted to be influenced by the proximity of a hand thereto to cause a high frequency loss in the circuit including the member and the hand, thereby causing a variation in the oscillating condition of the tank circuit, the variation serving to operate the solenoid valve.
The invention will be described in detail with reference to the drawings, in which FIG. 1 is a circuit diagram of an embodiment of the invention,
FIGS. 2 and 3 are simplified circuit diagrams of the oscillator circuit used in FIG. 1,
FIG. 4 is a circuit diagram of another embodiment of the oscillator circuit, and
FIG. 5 is an elevational view of the cock and the solenoid valve; illustrating the connection therebetween.
Referring to FIG. 1, the embodiment shown includes an oscillator tube 1 which is shown to be a pentode having an anode and a cathode interconnected by a capacitor 2. Across the control grid and cathode of the tube are connected a fixed capacitor 3 and a variable capacitor 4 in parallel, and the cathode is connected through a choke coil 5 to the negative terminal of a DC supply which is simply indicated by plus and minus symbols. The negative terminal is grounded through a bypass capacitor 6. The suppressor grid is connected with the cathode as usual and the screen grid is connected to the negative supply terminal through a bypass capacitor 7 and is also connected to the positive supply terminal through a relay coil 20 having associated contacts 21. The anode of the tube 1 is connected through a coil 8, a choke coil 9 and the relay coil 20 in series to the positive supply terminal, and the junction between the coils 8, 9 is connected through an insulating capacitor l0 and a coil 11 in series to the control grid of the tube 1. The capacitor 10 provides a DC isolation. The junction between the capacitor 10 and the coil lll is connected to the negative supply terminal through a parallel circuit including a grid leakage resistor 12 and a bypass capacitor 13. The anode of the tube l is also connected through capacitors l4, 15 in series to a high frequency output terminal 16. The whole oscillator circuit is housed in a metal casing 18, which is grounded.
The relay contacts 21 are connected in circuit with the energizing coil of a solenoid valve 22 which is connected in a water supply pipe 23. An insulator pipe 24 is connected to the free end of the supply pipe and a metal cock or faucet 25 is fitted to the insulator pipe 24. The cock 25 is electrically connected with the terminal 16.
The coils 8, 1 1 are tuning coils which cooperate with tuning capacitors 2, 3, 4 to form a tank circuit, which can be shown in a simplified form as illustrated in FIG. 2. In this FIG., numeral 30 denotes an inclusive capacitance across the anode and the cathode, including capacitor 2 and stray capacitances across these electrodes and those between connecting wires. Numerals 31, 32 similarly denote inclusive capacitances across the grid and cathode and across the grid and anode, respectively, and numeral 33 denotes an inclusive tuning coil. The equivalent circuit shown in FIG. 2 is known as a Colpitts circuit. When the capacitive reactance of the capacitor 32 is considered as included in the inductive reactance of the coil 33 and when the high frequency effective resistance of the coil 33 is included in the circuit by a resistor 34, the circuit takes the form shown in FIG. 3.
Considering the operation of the circuit shown in FIG. 1, it is assumed that the tank circuit comprising capacitors 2, 3, 4 and coils 8, 1 l is constructed to have a high Q-value. Then the loss caused by a grid current represents a substantial part of the high frequency effective resistor 34. Such grid current causes a high negative bias to be produced across the grid leakage resistor 12, so that the sum, I,, of anode and screen grid currents which flow through the relay coil 20 when the circuit is in oscillation will be very small. Thus in stationary condition, the current flow through the relay coil 20 is insufficient to energize it, so that the contacts 21 remain open.
If a hand is now reached toward the cock 25, this increases the high frequency loss or the effective resistance of the oscillator circuit, thereby decreasing the amplitude of the oscillation, with resulting decrease of the grid current and increase of the sum current I,. Ultimately a condition will be reached in which the oscillation is almost interrupted and the grid bias is removed so that the sum current I, assumes its maximum value, whereupon the relay coil 20 is energized to close the contacts 21, which operate the solenoid valve 22 for automatic delivery of water through the cock 25.
It is essential to ensure a high ratio of the sum current I, as between the time when the hand is extended toward the cock and the time when it is not, by achieving as high a Q-value as possible in the tank circuit. When the magnitude of the maximum sum current I, is sufficient to operate directly a solenoid valve such as is shown at 22, the relay may be eliminated.
In FIG. 1, the insulating capacitor and bypass capacitors 7, 13 are chosen to have a capacitance whose reactance is negligibly small at the frequency of oscillation. Thus no high frequency voltage is applied across the grid leakage resistor 12 to cause h.f. loss therein. When the inductances and mutual coupling of the coils 8, 11 are chosen such that the insulating capacitor 10 assumes a position which divides the voltage across the tuning coil 33 in a proportion determined by the capacitors 30, 31, the cathode potential becomes near the ground, thereby reducing the loss in the choke coi1'5 connected in the cathode circuit. There are varying stray capacitances from tube to tube across the anode and cathode and across the control grid and cathode so that adjustable capacitors may be connected thereacross to set the operating condition of the tube at optimum. Alternatively, a variable capacitor 17 may be used as shown in FIG. 4, this capacitor being constructed such that an increase (or decrease) of anode-cathode capacitance results in a decrease (or increase) of grid-cathode capacitance.
In FIG. 1, the capacitor represents an adjustable capacitor which may be adjusted to vary the degree of coupling. Where this capacitor 15 has good insulation, the insulating capacitor 14 may be eliminated. Proper adjustment of the coupling degree by the capacitor 15 prevents any poor insulation between the cock 25 and the supply pipe 23 from influencing the oscillator in a manner to cause an increased degraded, and thus an attempt must be made to find a suitable setting for the capacitor 15.
It is found that connection of the choke coil 5 in the cathode circuit from being useful in avoiding the oscillation condition is influenced by variation of the capacitance across the anode and the ground. The casing 18 is electrically connected with the drain and supply pipes 25 which are grounded, and thus the high frequency voltage is applied onlyto a localized area of the cock so that radio interference is substantially eliminated. However, it should be understood that the terminal 16 may be connected to an electrically conductive member placed in or adjacent the water basin to substitute for the cock 25, which then may be of insulating material.
FIG. 5 shows a preferred construction of the supply pipe and cock assembly in which the cock 25 is electrically insulated from the supply pipe 23 and the parts of a water basin adjacent the cock. The supply pipe 23 is connected with the inlet of a solenoid valve 22 whose outlet is connected with one end of the insulator pipe 24. The faucet or cock 25 is connected with the other end of the insulator pipe, and for the purpose of supporting the assembly, the faucet extends through an opening in a water basin 35 of conventional ceramic material and is clamped thereto by a nut 36, there being provided insulator bushings 37, 38 for preventing the faucet from being wetted by water. Preferably, water repellent materials having symmetrical molecular structure and minimum high frequency loss at the involved frequency, such as, for example, polyethylene, polystyrol, ethylene tetrachloride or the like, are used for the parts 24, 37, 38 in order to prevent the degradation of the sensitivity which may be caused by the presence of water and the resulting increased equivalent loss of the oscillator circuit. Because of the high frequency used, skin effect avoids any deleterious stimulus or influence upon the hand or any other part of the human body which may come into contact with the faucet 25. It should be understood that the oscillation power is sufficiently low to prevent any significant radiation of an electromagnetic wave, and with such power, the automatic cock device according to the invention is fully operative without danger to the human body.
1. Automatic cock device comprising a tank circuit having a high Q-value and including resistance and capacitance values, said tank circuit being constituted for oscillation at a frequency of around 40 Mc/S, a cock for a water basin, an electrically conductive member positioned adjacent the water basin, the member being electrically insulated from the ground, means for coupling the member electrically with the tank circuit, and a solenoid valve for allowing or. interrupting a flow of water through said cock, said member being adapted to be influenced by the proximity of a hand thereto to vary the resistance of the tank circuit and influence the Q-value to cause a high frequency loss in the circuit including the member and the hand, thereby causing a variation in the oscillating condition of the tank circuit substantially independently of capacitance change, the variation serving to operate the solenoid valve.
2. Automatic cock device according to claim 1, in which the tank circuit is coupled ina vacuum tube oscillator of Colpitts type, interelectrode capacitances of the tube across the anode and cathode and across the control grid and cathode constituting a part of the tank circuit.
3. Automatic cock device according to claim 1, in which the tank circuit is coupled in a vacuum tube oscillator of Colpitts type, the tank circuit including a tuning coil across the anode and control grid of the tube, said coil being divided, at a position having a high frequency potential substantially near the cathode potential, by a series DC isolation capacitor having a sufficiently low impedance to the oscillation frequency, one
said variable capacitor is in series with an insulating capacitor of high insulation. 7
6. Automatic cock device according to claim 1, in which the member is insulated from a water supply pipe and/or the water basin by material having symmetrical molecular structure and minimum high frequency loss at the frequency involved.
7. Automatic cock device according to claim 6, in which said material is polyethylene, polystyrol or ethylene tetrachloride. I v