Water purifier

Abstract: A water purifier (1) comprises an electrically conductive filter (22), a first electrode (30) electrically connected to the filter (22), a second electrode (31) arranged in a water channel in the water purifier (1) and electrically connected to the filter (22) through the water, voltage application means (4A,4B) for applying a voltage between the first and second electrodes (30,31), switching means for controlling application of the voltage from the voltage application means (4A,4B) between the first and second electrodes, exchange time detection means operable to discriminate the magnitude of the voltage of the voltage application means (4A,4B) and having display means (3a,5a) operable on the basis of the result of discrimination to indicate the time for exchanging the voltage application means (4A,4B), and detection controlling means for controlling activation of the exchange time detection means. By the water purifier (1), breeding of microorganisms in the filter (22) can be suppressed, while maintaining a long lifetime of the voltage application means (4A,4B) and appropriateness of the voltage of the voltage application means (4A,4B) can be ascertained when water flows through the water purifier(1).

Description: In a conventionally known water purifiers having a filter for removing minute inorganic material, organic material, residual chlorine, etc. which exist in waterworks, in order to suppress breeding of microorganisms in the filter, an electrically conductive filter is used to act as one electrode, the other opposite electrode is disposed in a water flow channel in the water purifier, and a voltage is continuously applied between both electrodes by a battery. The inventors have studied carefully the breeding of microorganisms in the filter and have first found the fact that the breeding of microorganisms such as bacteria tends to occur when water stagnates in the filter. In other words, the breeding of microorganisms in the filter tends to occur when water stagnates in the filter, but it hardly occurs when water flows through the water purifier. A problem found by the inventors in connection with the conventional water purifier is that the constant application of a voltage of a battery between the electrodes causes consumption of the battery and makes it difficult to assure long-term use of the battery. Another problem found by the inventors in connection with the water purifier having a voltage applied between the electrodes therein is that, in spite of the fact that a decrease in the battery voltage to be applied reduces the effect of suppressing the breeding of microorganisms, consumption of the battery can not be checked externally and the user can not decide whether exchange of the battery due to consumption thereof is needed or not. From JP-A-02-207884 there was known a water purifier with a positive and a negative electrode. The electrodes are provided for cleaning water and are connected to batteries for a prescribed period of time, e. g. for one second, during the operation of the faucet connected to the water cleaner. The energy supply of the electrodes is stopped by means of a switching means about one second after operating the faucet. A counter electromotive force is then generated between the positive and the negative electrode. The propagation of microorganisms in a filter of the water purifier is suppressed by the counter electromotive force even if said electrodes are not supplied with energy while the water purifier is not in use. That known water purifier does not teach the use of a water flow detection means for detecting water flowing through a water channel and voltage application means for applying a voltage to electrodes when no waterflow is detected by the water flow detection means. Moreover, the known water purifier gives no teaching to use a means to inform the user of the state of the battery which supplies energy to the electrodes. A first object of the present invention is to provide a water purifier having electrodes between which a voltage is applied by using a battery, which water purifier eliminates the necessity of exchange of the battery over a long period of time and suppresses breeding of microorganisms over a long period of time. A second object of the present invention is to provide a water purifier which prevents an accelerated reduction in the lifetime of the battery, and, when the battery becomes exhausted, timely informs the user of the state of the battery. The water purifier of the present invention comprises a water flow detection means, an electrically conductive filter disposed in a water channel in the water purifier, which water channel is filled with water at least when the water flow therethrough is stopped, a first electrode, a second electrode electrically insulated from the filter and disposed in the water channel, and a battery for applying a voltage between the first and second electrodes. A first embodiment of this invention is featured by comprising: water flow detection means for detecting the fact that water is flowing through the water channel; and voltage application means for applying a voltage of the battery between the first and second electrodes when water flow is not detected by the water flow detection means. A second embodiment of this invention is featured by comprising: water flow detection means for detecting the fact that water is flowing through the water channel; voltage discrimination means for checking whether the voltage of the battery exceeds a predetermined voltage value; and display means for indicating whether the battery voltage exceeds the predetermined voltage value when water flow is detected by the water flow detection means. In the first embodiment, the battery voltage is not applied between the first and second electrodes when water is flowing through the water channel, while the battery voltage is applied between the first and second electrodes only when water does not flow through the water channel and thus water stagnates in the water channel making the breeding of microorganisms tend to occur, thereby making it possible to suppress the breeding of microorganisms. Generally, in a water channel where a filter is disposed, when water is flowing through the water channel, such breeding of microorganisms hardly occurs, and therefore there arises no problem even if a voltage is not applied between the first and second electrodes during the water flow time period. In the second embodiment, a decision as to whether the battery voltage exceeds the predetermined voltage value necessary for suppressing the breeding of microorganisms and a display of the result of decision are effected only during the water flow time period. Generally, in a water supply equipment having a water purifier mounted on a faucet or the like in the water works, the time period during which water is made to flow is generally much shorter that the time period during which the water flow is stopped. Accordingly, if the decision on the magnitude of the battery voltage and the display of the result of that decision are effected each time when water flows through the water purifier, that is,only when the user has often the chance of looking at the display of the result of the decision on the magnitude of the battery voltage, it is possible to reduce the battery power consumption necessary for effecting the decision and display with respect to the battery voltage. The present invention provides the following meritorious effects. In accordance with the first embodiment, the voltage of the battery is not applied between the electrodes during the water flow time period, which is useful in reducing the battery consumption. Thus, the voltage application between the electrodes during the time period of stagnation of water, in which the breeding of microorganisms should be suppressed, can be continued over a long period of time. In accordance with the second embodiment, the discrimination of the magnitude of the battery voltage is effected and the result of discrimination is displayed when water flows through the water channel, whereby the necessity of exchange of the battery due to exhaustion thereof can be determined easily. In this case, the discrimination as to whether the battery is exhausted or not and the display of the result of discrimination are effected within a relatively short water flow time. Thus, the battery power consumption therefor can be reduced remarkably. Accordingly, the power supply battery can be used over a long period of time. The water purifier may also comprise sterilization means to generate an electric potential difference across the filter so as to sterilize said filter. The invention is further explained by the enclosed drawings. Fig. 1 is a circuit diagram showing the electric circuit of a control circuit board in one embodiment of the present invention; Fig. 2 is a sectional view showing a water purifier in one embodiment of the present invention; Fig. 3 is a schematic diagram showing the relation between respective electrodes and the water level in the filter unit in one embodiment of the present invention; and Fig. 4 is a time chart showing the operation of the water purifier of an embodiment of the present invention. An embodiment of the present invention will be described hereunder by making reference to the accompanying drawings. A water purifier 1 shown in Fig. 2 comprises a filter unit 2, a control circuit board 3, two batteries 4A and 4B, an outer cover 5 and a battery cover 6. The water purifier 1 is fixed to a faucet used in water works through an adapter 7. The filter unit 2 includes a filter case composed of a cylindrical main case 21 having one open end and a filter 22 arranged therewithin, an inner lid 23 so disposed as to block up the open end of the main case 21, and an outer lid 24 disposed to cover the inner lid 23. On the inner side surface of an upper wall 21a of the main case 21, six downwardly projecting filter supports 21b are disposed extending radially. The filter supports 21b are kept in contact with the filter 22 to support it, and the filter supports 21b define therebetween radial spaces acting as outflow paths 21c (indicated by dotted lines) through which water passing through the filter 22 can flow out. Respective lower open ends of the flowout paths 21c, which face the filter 22, are covered with a mesh 21d made of a synthetic fiber. This mesh 21d is fixed to each of the filter supports 21b at the time of formation of the main case 21. The filter 22 is made of an active carbon fiber layer which has been formed to be fully permeable to water and has a density of 0.17 g/cm³, for example. Formed in the upper wall 21a are funnel-shaped electrode insertion holes 25a, 25b and 25c in which there are inserted respectively a positive electrode 30, a negative electrode 31, and a detection electrode 32, each thereof having a lead wire and being made of a carbon rod, for example, and being fixed with an epoxy adhesive 26. The positive electrode 30 penetrates the filter support 21b and is inserted in the filter 22 making electrical contact therewith, thereby causing the filter 22 to function as a part of the positive electrode 30. Under the electrode insertion hole 25b in which the negative electrode 31 is inserted and supported, an insulating sleeve 21e formed integrally with the upper wall 21a penetrates the filter 22 and is fitted in the inner lid 23, and the negative electrode 31 extends through the insulating sleeve 21e and the inner lid 23 to project from the inner lid 23 and to abut against the outer lid 24. The detection electrode 32 is disposed to detect whether the outflow paths 21c formed between the adjacent filter supports 21b are filled with water or not, and it projects slightly from the inner side surface of the upper wall 21a so that the length of its portion projecting downwardly from the upper wall 21a is shorter than the height of the filter supports 21b. A pipe member 27 having six legs 27a at one end thereof is bonded fixedly to the inner central portion of the upper wall 21a to extend downwardly, and the upper end portion of the pipe member 27 communicates with the outflow paths 21c through gaps between adjacent legs 27a. The upper surface of each of the legs 27a is so curved as to keep away from the detection electrode 32 slightly projecting from the upper wall 21a. This configuration ensures that, when the inflow of water into the water purifier 1 is stopped, water in the outflow paths 21c drops downward easily and does not remain bridging between the leg 27a and the detection electrode 32 due to the surface tension of water. The inner lid 23 having a form of a substantially circular disk corresponding to the main case 21, supports the filter 22 at its lower side and has a plurality of inflow holes 23a formed corresponding to the outflow paths 21c in the main case to act as open spaces through which water flows into the filter 22. The upper side of the opening of each inflow hole 23a facing the filter 22 is covered with a mesh 23b made of a synthetic fiber which is fixed to the inner lid 23 at the time of formation thereof. The central portion of the inner lid 23 is formed to be integral with a boss 23c, which is fitted into the pipe 27, and the central portion of the inner lid 23 is also formed to be integral with a pipe portion 23d which is positioned on the opposite side to the boss 23c and defines a drain pipe in conjunction with the pipe member 27. The outer lid 24 is fitted to an outer cylinder portion 21f of the main case 21 to confine the inner lid 23 therein, and it defines, between the outer and inner lids 24 and 23, an inflow path 24A which communicates with the inflow holes 23a. Disposed at the lower portion of the outer lid 24 is an inflow pipe 24a which is formed to confine therein the pipe portion 23d of the inner lid 23. Disposed in the inflow path 24A is a check valve 28 which is fixed to the pipe portion 23d and which prevents the counterflow of water within the inflow path 24A, the inflow holes 23a and the filter 22 into the inflow pipe 24a, when the inflow of water from the inflow pipe 24a is stopped. The filter 22 has holes through which the aforementioned insulating sleeve 21e and the pipe member 27 penetrate and in which the positive electrode 30 is inserted. In Fig. 2, denoted by 7a and 7b are O-ring for providing water-tightness between each of the outer lid 24 and the pipe portion 23d and the adapter 7 of a double-pipe structure. With the water purifier 1 having the above-described construction, when water is supplied into the inflow pipe 24a through the adapter 7, the inflow water opens the check valve 28, flows through the inflow path 24A, the inflow holes 23a and the mesh 23b, flows through the filter 22 where the inflow water is filtrated, then flows through the mesh 21d, the pipe member 27 and the pipe portion 23d, and finally flows out of the adapter 7. At that time, the filter unit 2 is filled with supplied water and mutual electrical conduction is established among the positive electrode 30, the negative electrode 31 and the detection electrode 32 through the supplied water. On the other hand, when water supply is stopped, the check valve 28 is closed and water in the filter 22, the inflow holes 23a and the inflow path 24A stagnates and is retained within the filter case. At that time, water in the pipe member 27 and the pipe portion 23d operating as the outflow pipe and in the outflow paths 21c drops spontaneously and flows out of the filter case. As a result, the electrical conduction between the positive electrode 30 and the negative electrode 31 can be continued by the presence of water, but the detection electrode 32 is electrically separated from both the positive and negative electrodes 30 and 31 to stop the electrical conduction therebetween. In the filter unit 2 having the above-described construction, the respective electrodes 30 to 32 are connected to the control circuit board 3 disposed between the main case 21 and the outer cover 5 so that predetermined operations may be carried out, and a light emitting diode 3a may be activated to provide a predetermined display through a transparent window 5a disposed in the outer cover 5. The control circuit board 3 will be described with reference to the accompanying drawing. Fig. 1 is an electric circuit diagram of the control circuit board 3, in which reference numerals 30, 31 and 32 denote the aforementioned positive, negative and detection electrodes, respectively, and reference numerals 4A and 4B represent the batteries. A transistor TR1 acts as means for deciding whether water is supplied into the filter unit 2 or not by checking whether electrical conduction is established between the detection electrode 32 and the negative electrode 31, and, when electrical conduction is established between the detection electrode 32 and the negative electrode 31, the base current path is established through resistors R1 and R2, so that the transistor TR1 becomes conductive. When the transistor TR1 is turned conductive, transistors TR2 and TR3 turn conductive and permit power supply to a transistor TR4 operating to light up the light emitting diode 3a. An electric circuit including a transistor TR5 constitutes voltage discrimination means for deciding whether the voltage of the battery 4B is equal to or higher than a predetermined voltage value of 0.7 V which is sufficient to suppress breeding of microorganisms within the filter 22. Display of the result of decision is made by controlling the conduction of the transistor TR4 when a voltage is applied between the collector and the emitter of the transistor TR4. For this purpose, the transistor TR5 operates to vary a base current of the transistor TR4 in accordance with the result of discrimination of the magnitude of the battery voltage to control conduction of the transistor TR4. More specifically, when the voltage of the battery 4B exceeds the predetermined voltage value, the transistor TR5 is turned conductive by the base current determined by resistors R3 and R4 to drive the transistor TR4 to become conductive, which in turn lights up the light emitting diode 3a. On the contrary, when the voltage of the battery 4B is lower than the predetermined voltage value, the transistor TR4 is not rendered conductive, so that the light emitting diode 3a is not lit up. On the other hand, a transistor TR6 is disposed to control conduction of a transistor TR7 which operates to apply the voltage of the battery 4B to the positive electrode 30. When the transistor TR1 is turned conductive, the transistor TR6 turns conductive and the base of a transistor TR7 is grounded, with the result that the transistor TR7 is made nonconductive, thus preventing the voltage of the battery 4B from being applied to the positive electrode 30. Conversely, with the transistor TR1 turned nonconductive, the transistor TR6 turns nonconductive and a bias voltage is applied to the base of the transistor TR7 through a resistor R6 to make the transistor TR7 conductive, thereby causing the voltage of the battery 4B to be applied to the positive electrode 30. In Fig. 1, reference numeral 3A represents a connector terminal through which the control circuit board 3 is connected to the respective electrodes and the batteries 4A and 4B. With the water purifier 1 of the embodiment of the present invention having the above-described construction, when water is supplied by manipulating a faucet not shown, the filter unit 2 is filled with water up to a water level shown by an arrow M in Fig. 3. In this state, electrical conduction is established between the detection electrode 32 and the negative electrode 31 through the supplied water, and thus water flow is detected. At this time, the transistor TR7 is made nonconductive, as described above, and the application of the voltage of the battery 4B between the positive electrode 30 including the filter 22 and the negative electrode 31 is interrupted. On the other hand, during the period of interruption of the application of the voltage of the battery 4B, the voltage of the battery 4B is checked as to whether it exceeds the predetermined voltage value, and, if the battery voltage is determined to be equal to or higher than the predetermined voltage value, the light emitting diode 3a is lit up, indicating that the battery 4B still retains a sufficient lifetime. Conversely, when the voltage of the battery 4B is lower than the predetermined voltage value, the light emitting diode 3a is not lit up, indicating that the battery 4B does not retain a voltage necessary for suppressing breeding of microorganisms. This permits the user to determine easily that exchange of the battery is needed. When the faucet is manipulated to stop water supply, the check valve 28 is closed, and water remains within the filter unit 2. At this time, water in the flowout paths 21c, the pipe member 27 and the pipe portion 23d is drained, and the water level is lowered as shown by an arrow N in Fig. 3, and hence electrical conduction between the detection electrode 32 and the negative electrode 31 is turned off. At this time, the transistor TR7 is made conductive as described previously, and the voltage of the battery 4B is applied between the positive electrode 30 including the filter 22 and the negative electrode 31 to suppress breeding of microorganisms. The above relation is shown schematically in the time chart of Fig. 4. In the Figure, the ON-state in the water flow detection curve corresponds to the electrical conduction state between the detection electrode 32 and the negative electrode 31, and the ON-state in the curve of the application of voltage corresponds to the application of the voltage of the battery 4B between the positive electrode 30 including the filter 22 and the negative electrode 31. As described above, according to the present invention, a voltage sufficient for suppressing breeding of microorganisms can be applied between the individual electrodes only when water flow is stopped, and therefore consumption of the battery can be reduced to insure long-term use thereof. When water flows through the filter unit 2, since the voltage of the battery is discriminated as to whether it exceeds the predetermined voltage value necessary for suppressing breeding of microorganisms and the result of discrimination is displayed, necessity or non-necessity of exchange of the battery can be determined readily. In this case, the discrimination and display with respect to the battery voltage is effected only during the water flow time period which is much shorter than the water flow stop time period, and hence only a small amount of battery power is consumed for this purpose. Accordingly, the lifetime of the battery is not shortened and long-term use of the battery can be ensured. Further, in the embodiment of the present invention, the application of a voltage between the positive and negative electrodes and the discrimination and display with respect to the magnitude of the battery voltage are effected alternately. Thus, at the time of effecting the discrimination and display with respect to the magnitude of the battery voltage, no voltage is applied between the positive and negative electrodes, and thus it can be assured that the battery voltage can be determined correctly, and further the light emitting diode requiring an amount of power more than that consumed at the time of application of the battery voltage between the positive and negative electrodes can be lit up assuredly.

Claims: A water purifier, characterized by: a water flow detection means; a water channel for making a water flow to a drain port; an electrically conductive filter (22) disposed in said water channel and operable to purify the water flowing through said water channel by the filtration thereof; a first electrode (30) electrically connected to said filter (22); a second electrode (31) arranged in the water in said water channel and electrically connected to said filter (22) through the water; voltage application means (4A, 4B) for applying a voltage between said first and second electrodes (30, 31); and switching means for switching conduction or nonconduction between said voltage application means (4A, 4B) and said first and second electrodes (30, 31). A water purifier according to claim 1, wherein said switching means has a water flow detection unit for detecting that water flows through said water channel and makes said voltage application means (4A, 4B) conduct to said first and second electrodes (30, 31) only when a water flow is not detected by said water flow detection unit. A water purifier according to claim 1, wherein there are provided an exchange time detection means operable to detect the voltage of said voltage application means (4A, 4B) and having display means (3a, 5a) for informing the user of the time of exchanging said voltage application means (4A, 4B) when the voltage of said voltage application means (4A, 4B) is lower than a predetermined voltage value; and detection controlling means operable to actuate or stop said exchange time detection means. A water purifier according to claim 3, wherein said detection controlling means operates to actuate said exchange time detection means only when the water flows through said water channel. A water purifier according to any of claims 1 to 4, wherein said voltage application means (4A, 4B) comprises a battery. A water purifier according to claim 1 or 3, wherein said switching means has a water flow detection unit for detecting that water flows through said water channel and makes said voltage application means (4A, 4B) conduct to said first and second electrodes (30, 31) only when a water flow is not detected by said water flow detection unit. A water purifier according to claim 3 or 6, wherein said detection controlling means operates to actuate said exchange time detection means only when the water flows through said water channel. A water purifier according to any of claims 3 to 7, wherein said display means in said exchange time detection means comprises at least one of a lamp, a buzzer, a chime and a display unit. A water purifier according to claim 1, wherein there are provided sterilization means operable to generate an electric potential difference across said filter so as to sterilize said filter (22); and switching means for switching the operation or non-operation of said sterilization means. A water purifier according to claim 9, wherein said switching means has a water flow detection unit for detecting that water flows through said water channel and activates said sterilization means only when water flow is not detected by said water flow detection unit.

Inventors: OIKAWA YUKIO, SAITO SHIRO, SHIGETA ISAMU, OIKAWA, YUKIO, SAITO, SHIRO, SHIGETA, ISAMU
Applicants: INAX CORP, INAX CORPORATION
Application year: 1991
Main classification: C02F1
IPC codes: C02F1