10.3. Age of documents – time factor

The age of documents known long before the filing date might only be an indication of an inventive step if a need for the solution of an unsolved problem had existed for the entire period between the date of the documents and that of the invention (T 79/82, T 295/94). Nevertheless, the long period of time to be considered was not the period that had elapsed between the publication of a document and the filing of the European patent application disclosing the teaching of that document, but that between the time the problem became apparent and the date of filing of the European patent application providing a solution (T 478/91).

In T 273/92 the board held that a period of 23 years between the publication date of the document deemed to be the closest prior art and the priority date of the contested patent in an economically significant and frequently studied field could normally be viewed as an indication of the presence of inventive step. In T 203/93 and T 795/93 a period of 11 years was considered to be an indication in support of inventive step, in T 986/92 a period of 70 years, in T 478/91 80 years and in T 626/96 60 years. See also T 774/89, T 540/92, T 957/92, T 697/94, T 322/95, T 255/97, T 970/97, T 6/02, T 2271/08.

In T 330/92 the documents reflecting the general knowledge available to experts in the field of the application (injection mould technology for cashcard holders) had been published at least 17 years before the filing date of the contested patent. The board of appeal pointed out that the elements which could have led to the feature combination of claim 1 had thus long been known in the prior art for some time. Nevertheless the experts had for all this time been "blind" to these findings. Nor had other applicants in the same field made use of the knowledge in question.

In T 1077/92 the board faced the unusual situation of a problem and its ready solution having co-existed for 100 years in general, and more recently in a field of intensive research, and still the seemingly obvious step had not been taken. The board concluded that, as no other explanation could be found, this must have been because inventive insight was needed. In T 617/91 the board compared the 100 year interval in T 1077/92 to the seven year interval between D1 and the priority date of the alleged invention in the case in hand. The board noted that despite there being a strong incentive amongst SG iron makers throughout that time interval to look for better methods which would be safer, and more economical, throughout that interval the teaching of D1 was ignored. Consequently, although D1 seen in hindsight seemed to suggest a solution, the board drew the inference that the generality of its teaching was such that it remained unnoticed, and would have remained so but for the inventive insight of the appellant.

In T 123/97 the board found the failure to adopt an obvious solution to the technical problem underlying the patent in suit may have resulted from a variety of causes; for example, there may have been a commercial reason for not adopting this new technique, because the old technique was found satisfactory by the clients and could also be improved, thus avoiding considerable investment costs involved in the adoption of a new technique on an industrial scale. Therefore in the board's judgement, the claimed use according to claim 1 did not involve an inventive step.

The board in T 833/99 found that, in addition to the other factors it had mentioned in examining whether a method of producing a grooved-rail frog for tramlines was inventive, it also had to be taken into account that citation D1 dated from 1930 and that, in the 60 years between it and the invention at issue, no skilled person had had the idea of taking up what it suggested and applying the method described to a single-piece frog. That was a serious indication of non-obviousness which could not be ignored.

The board in T 1192/09, having found that there was an inventive step, added that the actual developments in the relevant technical field, as evidenced by the documents on file, provided additional support in favour of an inventive step. The board noted in this respect that D8 (closest prior art) had been published about 12 years before the filing date of the patent in suit. The fact that the very inventors of D8 had not proposed the claimed structure, with its uncontested advantages, until 12 years after the publication of D8, and that this structure had later been praised in D10 (European patent, same inventors as D8, underlying application filed two months after the patent in suit) and made the subject of a granted European patent was considered by the board to be an additional indication of the non-obviousness of the concept which formed the basis of the claimed invention.