T 0675/93 (Water purification/TARN-PURE) 16-09-1997

1. Admissibility of the appeal

1.1. The written decision under appeal was posted on 12 May 1993 which means that it is deemed to be delivered ten days later on 22 May 1993 (Rule 78(3) EPC). The Statement of the Grounds of Appeal was received by the European Patent Office on 22 September 1993, i.e. within 4 months after the date of notification of the written decision as required by Article 108 EPC. The stamp dated 23 September 1993 indicates merely the date at which the telefax of 22 September 1993 arrived at the registry of the Boards of Appeal (General Directorate 3). Decisive for the filing date is, however, only the date at which the telefax was received by the Office. The telefax containing the Statement of Grounds was thus received in due time.

1.2. As no assignment has been registered with the EPO, the Appellant (Patentee) remains the registered company Tarn Pure Limited. The copy of the confirmatory assignment agreement of 25 March 1992 filed on 14. November 1994 in answer to a communication of the Board, and the earlier deed of assignment of 10. November 1989 referred to therein, indicate that Tarn Pure Limited are acting as bare trustee of the patent for Tarn Pure Technology Corporation, Inc. (TPTC). By clause 2.3 Tarn Pure Limited have inter alia undertaken to do all acts to vest in TPTC absolutely the full benefit of the inventions of the patents. This covers being a party to the appeal proceedings until such time as the assignment is recorded in the EPO. For an assignment to be recorded in the EPO, a request to that effect must be filed, and the administrative fee paid (see Rule 20 EPC). This is not the case here, so the Board can only treat Tarn Pure Limited as the patentee and appellant at the date the appeal was lodged. Tarn Pure Limited being the party who was adversely affected by the decision under appeal had the right to appeal (Article 107 EPC). Since further Andrew Birkby Crawford was appointed by Tarn Pure Limited as its representative in all proceedings before the EPO, which appointment was never withdrawn and in fact confirmed by the Liquidator of Tarn Pure Limited, the Board considers the appeal signed by Andrew B. Crawford in the name of Tarn Pure Limited, to be admissible.

2. Main request

2.1. Amendments

Amended claim 1 differs from claim 1 as granted in that it contains the additional feature that the circuitry is capable of supplying a current of 900 milliamps (mA). Because claim 1 also requires that the water purification apparatus comprises a circuitry for maintaining a stable current between the electrodes, the additional feature implies in the context of claim 1 that the circuitry should be capable of supplying a stable current of 900 mA.

According to the description as originally filed, the output is at 34 to 36 volts and results in an output current of between 100 and 500 mA with a peak of 900 mA (page 4, lines 16 to 18). There is no other reference in the description to the current. According to claim 1 as originally filed the apparatus comprises a circuitry for maintaining a stable current between the electrodes. There is thus support for "a stable current up to 500 mA". According to the Appellant the word "peak" means in this context "maximum constant current" or "maximum stable current". The Board, however, can see no clear and unambiguous support for this allegation. Since in the opinion of the Board a "peak current" is not the same as a "stable current", there is no support for "a stable current up to 900 mA". The main request, therefore, does not comply with Article 123(2) EPC and cannot be allowed.

3. Auxiliary request

3.1. Amendments

As indicated above, "a stable current of up to 500 mA" is based on the application as originally filed. The Board sees no objections under Article 123 EPC against the claims of the auxiliary request. Since such objections have in fact not been raised by the Respondent, the amendments can be accepted without further comment.

3.2. Novelty

3.2.1. The prior art before the Board does not reveal an apparatus having all the features of claim 1. The closest prior art is considered to be D1. This document is undated but by testimony of Mr Benjamin Riley in the affidavit dated 7 February 1992 filed on 17 February 1992, it is credible that it was in the public domain before the priority date of the patent in suit. Moreover, in the Statement of Grounds of Appeal the Appellant explicitly stated that it was not contested that this document and the device disclosed therein were available to the public without any conditions of confidentiality before the priority date of the patent in suit.

3.2.2. D1 discloses all the features of present claim 1 except explicit information about the current that the described apparatus (WOCO-device) is able to supply. Disclosed therein is an experiment in which the apparatus turned to full supplied an electric current of 40 mA. This does not mean that the WOCO-device was not able to supply higher currents since the current is dependent upon the conductivity of the water. On the other hand, there is no evidence that the WOCO-device could supply a current of up to 500 mA. Even if the Respondent's allegation that, the output current of the WOCO-device is controlled by a 15 amp transistor, were accepted, this does not mean that the circuitry as a whole was able to supply a stable current of 500 mA. Moreover, in the tests with the WOCO-device under various loads (Affidavit of Jerry Minchey dated 6. February 1992) provided by the Respondent on 17. February 1992, the current in the highest switch position was never higher than 240 mA.

In the absence of conclusive evidence to the contrary the Board cannot accept that the WOCO-device is able to supply a stable current of 500 mA. The subject matter of claim 1 must, therefore, considered to be novel.

3.3. Inventive step

3.3.1. It is undisputed that D1 represents the closest prior art. The WOCO-device disclosed therein is used to purify swimming pools by releasing copper and silver ions which prevent bacteria and algae from growing in water. According to D1 these ions rid the water of all algae and bacteria making the water so pure you can drink it and the electronic circuitry controls the release of copper and silver ions such that the swimming pool water keeps sterile with no chlorine. According to the Appellant the WOCO-device does not operate satisfactorily over long periods of time under practical conditions because it does not supply sufficient energy to purify a substantial body of water and keep it purified (Appellant's letter filed 22 March 1996, page 5).

3.3.2. Starting from D1 the technical problem underlying the invention is considered to be to provide a more effective water purification apparatus which can purify a substantial body of water over long periods of time. According to claim 1 this problem is solved by providing an electrical circuitry capable of supplying a current of up to 500 mA. Although there are no comparative examples on file which unambiguously show that an apparatus according to claim 1 is more effective than the WOCO-device, it is credible that an apparatus according to claim 1, having more electrical power and providing more ions per time unit than the WOCO-device, is a more effective water purification apparatus. In fact, the Respondent never contested that an apparatus according to claim 1 would be able to purify a substantial body of water over a longer period. The Board is, therefore, satisfied that the said problem is actually solved by the claimed apparatus.

3.3.3. It remains to be decided whether, for solving the above stated problem, the claimed solution would have been obvious to a person skilled in the art.

The water purification effect obtained with electrical water purification devices such as the WOCO-device is based on the release of heavy metal ions such as copper and silver ions, which above a certain concentration kill algae and bacteria. On the evidence, ions are used up in killing bacteria and algae as these form clumps incorporating the ions, which clumps will be filtered out of the water system. The water purifying device must thus provide a sufficient current to initially build up the ion concentration to a sufficient level at which the concentration of bacteria and algae is very low, and then be able to maintain this ion level even in conditions which favour the growth of bacteria or algae. The larger the pool the greater must be the risk that even the maximum possible rate of ion production of a particular device is easily matched by the rate of removal of ions in clumps of filtered bacteria and algae, so that no sufficient ion level builds up in the pool serving to keep bacteria and/or algae at an acceptably low level.

It is thus the Board's opinion that, if the cleaning effect of such an apparatus for a specific body of water such as an outdoor swimming pool is unsatisfactory, even if used in its highest capacity mode, a skilled person would consider increasing its capacity. Since the release of ions is proportional to the electric current, an increase in capacity requires the use of higher currents and thus a device which is capable of supplying higher currents. To what extent the capacity should be increased depends of course on its intended use. A larger pool would require a higher rate of ions than a smaller pool. In order to determine to what extend the capacity can be easily increased, the skilled person would consider the circuitry of related water purification apparatus known in the art.

3.3.4. D2 discloses a closely related apparatus, whereby the electrolytic cell differs from the cell in the WOCO-device only in the form and arrangement of the electrodes. The circuitry of the apparatus disclosed therein is capable of supplying a constant current at 1.80. A (column 4, lines 64 to 71). Since a circuitry with an output capacity of more than 1 A belongs to the state of the art and has been used, or at least has been proposed for use in an electrical water purifier, it is obvious to increase the capacity of the WOCO device by replacing its circuitry by an upgraded circuitry which is capable of supplying at least 1 A.

3.3.5. The main argument against obviousness put forward by the Appellant was that the skilled person did not know why the WOCO-device failed so that he would not know what measure to take in order to solve the problem. This was allegedly demonstrated by the fact that Mr Minchey, an expert in the field of water purification, who has been involved in the treatment of swimming pool water since 1982 (Affidavit dated 6. February 1992) was allegedly not able to overcome the insufficiency of the WOCO-device (see FTC News dated 10. June 1992).

The Board cannot accept this argumentation for the following reasons.

There is no evidence before the Board that the WOCO-device would not work adequately to purify pools of a sufficiently small size. As on the evidence it was marketed for many years it seems inherently implausible that it did not work on some scale. The Board is unable to see any qualitative difference between what can be achieved by the WOCO-device and what can be achieved by the now claimed device. There seems only a quantitative effect relating to the maximum size of pool or other body of water that can be kept purified. Even assuming that the brochure relating to the WOCO-device promised more than it actually could perform, and that the WOCO device is insufficient for large pools, this does not mean that the skilled person was not aware that the deficiency of the WOCO device was related to the insufficient capacity of the WOCO-device. The charges of the Federal Trade Commission in the United States of America against Caribbean Clear, Inc. took place many years later than the priority date of the patent in suit. The fact that the said company tried to sell the WOCO-device with methods which were objected to by the said commission has no bearing on the question whether, at the priority date of the patent in suit, the skilled person was able to detect the ground for the failure of the WOCO-device when applied to outdoor pools of considerable size.

3.3.6. The Board also cannot accept the Appellant's argument that, since even a sixfold increase of the maximum current of 40 mA to 240 mA did not solve the problem the skilled person would not consider currents of up to 500 mA as now claimed, which are more than 10 times higher.

Although D1 does indeed disclose a test whereby the apparatus turned to the full gave an electric current of only 40 mA, this does not mean that the WOCO-device could not supply higher currents. The current is not only dependent upon the applied voltage but also on the conductivity of the water. Chemical analyses in the said test showed that after one hour 28 mg copper was released. D1 further discloses that it can be assumed that release of copper from the electrode is proportional to the electric current, so that a more rapid release of copper is obtained for water with high conductivity and that if the apparatus uses the maximum current recommended, 210 mg copper will be released per hour. The maximum current is not explicitly disclosed, but because of the indicated relationship between electrical current and release of copper, the maximum current can be calculated to be 210/28 times 40 mA = 300 mA. If 300 mA is still insufficient for killing the algae, it is in the opinion of the Board obvious to increase the current, whereby a twofold increase to about 600 mA will reasonably be taken into consideration by the skilled person.

3.3.7. The Appellant's further argument that the problem is not linked with the size of the pool but only with the reproduction rate of the organisms and that the basis of the invention was the finding that the production rate of the ions had to be higher than the reproduction rate of the algae and bacteria, is not convincing either.

The reproduction rate of the organisms is reduced by the presence of the ions and thus dependent upon the concentration of the ions. The concentration of the ions is however directly related to the size of the pool. It is thus highly unlikely that the performance of electrical water purifiers is independent of the size of the pool. If the skilled person detects that the algae and bacteria are still reproducing at an undesirable rate despite the introduction of copper and silver ions in the pool he will try to increase the production rate of these ions because he knows that at a sufficiently high concentration of these ions those organisms will no longer reproduce but are killed. The only way of increasing the production rate of ions is to increase the current.

Claim 1 of the auxiliary request, therefore, lacks an inventive step in the meaning of Article 56 EPC.

3.3.8. The Board observes that the reasons above for lack of inventive step also had applied to claim 1 of the main request, had this claim satisfied Article 123 EPC.