T 0401/88 (Test piece) of 28.2.1989

Summary of Facts and Submissions

I. European patent application No. 84 116 226.6 (publication No. EP-A-0 154 033) was refused by the Examining Division.

II. The grounds for refusal were that on the basis of two documents cited in the European search report the subject-matter of the claims as now worded lacked the inventive step required under Article 52(1) and 56 EPC.

III. The appellants filed notice of appeal against this decision.

IV. In a communication the Board of Appeal advised the appellants in particular that, in its view, Claim 1 as now worded contravened Article 123(2) EPC because it no longer contained the feature whereby the value for the test piece's starting capacity and the value for its state of charge provided an indication of its physical condition, and that it therefore contained subject- matter which extended beyond the content of the application as filed.

V. In the course of oral proceedings the appellants requested that the contested decision be set aside and the patent granted on the basis of either Claims 1 to 12 (main request) or Claims 1 and 2 (alternative request), both of which requests had been submitted during the oral proceedings.

VI. Claim 1 according to the main request, which is identical to the Claim 1 with which the contested decision was concerned, is worded as follows:

1. A method for testing direct-current sources such as accumulators, batteries and the like by measuring the open- circuit voltage after heavy-current loading, and the internal resistance, of the direct-current source to be tested (test piece) and determining its instantaneous charge from those measurements, characterised in that, by comparing the measured direct-current internal resistance (RS) with the known direct- current internal resistance (RSN) of a new, fully charged direct- current source of a similar type to the test piece, a value is obtained for the instantaneous starting capacity of the test piece (10), whose direct-current internal resistance (RS) is determined by measuring its terminal voltage (UA) at a point in time (t1) during heavy-current loading and establishing the difference between the open-circuit voltage and the terminal voltage (UB, UA). Claims 2 to 7 according to the main request are dependent on Claim 1, while Claims 8 to 12 relate to a test apparatus. Claim 1 according to the alternative request reads as follows: Test apparatus for implementing a method for testing direct- current sources by measuring the open-circuit voltage after heavy-current loading, and the internal resistance, of the direct-current source to be tested (test piece) and determining its instantaneous charge from those measurements, having at least one input terminal (15) for connecting the test piece (10), a loading resistor (17), connected via a first switch (16) to the input terminal (15), for heavy-current loading of the test piece (10), a first operational amplifier (18) to whose inverting input a reference voltage is applied and whose non-inverting input is connected via a second switch (20) to the input terminal (15), a second operational amplifier (19) whose inverting input is connected via a second switch (20) to the input terminal (15), a second operational amplifier (19) whose inverting input is connected via a third switch (21) to the input terminal (15) and whose non-inverting input is connected to the non-inverting input of the first operational amplifier (18), a timer (28) connected to the control inputs of the switches (16, 20, 21) and designed to selectively apply staggered closing signals of differing duration to the switches (16, 20, 21) so that the first switch (16) is closed during heavy-current loading, the third switch (21) is closed briefly during heavy-current loading after the first switch (16) has closed and the second switch (20) is also closed briefly after a recovery phase once the first switch (16) has reopened, and also having an inverting amplifier (24) connected in series after the second operational amplifier (19) and equipped with a preferably adjustable input resistor (25), a storage element - preferably a capacitor (22, 23) - being connected in parallel with the inputs of the two operational amplifiers (18, 19) connected to the input terminal (15), while a display (12) for indicating the state of charge is connected to the output of the first operational amplifier (18) and a display (13) for indicating the starting capacity of the test piece (10) to the output of the inverting amplifier (24)." Claim 2 according to the alternative request is dependent on Claim 1.

VII. In response to the Board's communication objecting to an inadmissible extension of the application the appellants argued essentially as follows: In Claim 1 as originally filed, two operations were erroneously combined which could not, however, be regarded as connected with each other. First, the terminal voltage UA during heavy-current loading and the open-circuit voltage UB after heavy-current loading were established to give reliable separate indications of the test piece's instantaneous starting capacity and instantaneous charge. These criteria, thus separately determined, were then combined to produce a signal corresponding to the test piece's physical condition. To a skilled person it was immediately apparent from the documents as originally filed that the basic teaching of the application was to be seen in the first operation only and that the second was merely a subsidiary extension of that first innovative concept. After all, the details in the description explaining how the test piece's physical condition was established (see page 6, line 22 to page 7, line 8) made it clear that its state of charge and starting capacity served as a basis for further determining its physical condition. Nor was this assessment of the innovative concept proper affected by the fact that the test apparatus described in the application had a logic circuit (27) which controlled a display (14) for indicating the test piece's physical condition. That apparatus was presented merely as an embodiment and a skilled person could immediately see that that type of logic circuit plus display could if necessary be dispensed with. Furthermore, the amendment in Claim 1 to which the Board objected was only a correction of obvious errors in the application documents as allowed under Rule 88 EPC.

Reasons for the Decision

1. The appeal is admissible.

2. Re the main request:

2.1 Claim 1 under the main request differs from Claim 1 as originally filed mainly in no longer containing the feature originally claimed whereby "the value for the test piece's starting capacity and the value for its state of charge providedd an indication of its physical condition on the basis of a known functional relation between the starting capacity of a direct- current source of similar type to the test piece and its state of charge and physical condition." The protection sought under Claim 1 as now worded therefore covers a method which provides no indication at all of the test piece's physical condition. The Board considers, however, that such a method is neither expressly described in the documents as originally filed nor directly inferable from them. The introduction to the description as originally filed clearly states that the particular advantage of the invention over the method known from document DE-B-2 926 716 - which also provides information about the test piece's physical condition, although this information is not always guaranteed reliable (page 1, last paragraph to page 2, second paragraph) - is that it provides a more reliable indication of the test piece's operating condition (page 2, last sentence). The definition of the invention as now worded in Claim 1, according to which the test piece's physical condition is no longer indicated, is therefore manifestly at odds with what was originally described as the invention. Furthermore, the sole test apparatus described in the application documents with reference to Figure 1 incorporates a logic circuit (27) which has an associated display (14) for indicating the physical condition of the test piece and which was also one of the features of the independent apparatus Claim 8 as originally filed, so that the original disclosure of the test apparatus also provides no evidence of a method which does not give an indication of the test piece's physical condition. The Board cannot agree with the appellants' submission that, to a skilled person, the features in the original Claims 1 and 8 relating to an indication of the test piece's physical condition and to a logic circuit and display provided for that purpose are obviously inessential and subsidiary. The significance of a feature can only be assessed in the light of the application documents as a whole and in particular by taking into consideration the technical problem of the invention inferable from them. So if an application, for whatever reasons, originally clearly discloses an invention as a combination of features solving a particular problem, then one of those features, without which the problem can no longer be solved, cannot be regarded as obviously inessential to the original disclosure. The change to the protection sought under Claim 1 thus means that the present application is amended in such a way that it contains subject-matter which extends beyond the content of the application as filed. Such a change is not permissible under Article 123(2) EPC.

2.2 The Board does not share the appellants' view that the amendment to the claims can be allowed under Rule 88, second sentence, EPC, whereby a description, claims or drawings may be corrected on request, provided that the correction is obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction. As explained above when the admissibility of the amendments under Article 123(2) EPC was under consideration, a skilled person cannot infer the requested amendments from the original documents. Similarly, a correction cannot be allowed under Rule 88, second sentence, because it is not immediately evident that nothing else would have been intended than what is offered as the correction. A requested amendment which represents an inadmissible extension within the meaning of Article 123(2) EPC cannot be allowed as a correction under Rule 88, second sentence, EPC since the European Patent Office may not extend the original disclosure by means of a correction. This follows from Article 138(1)(c) EPC under which a European patent may be revoked if its subject-matter extends beyond the content of the application as filed. This ground for revocation also applies if the inadmissible extension is based on a correction under Rule 88, second sentence, EPC. Clearly, then, a correction may not result in an extension of the original disclosure. Indeed, an error may only be corrected if its requested correction would be regarded by the skilled person - for whom the patent application is intended - as necessarily implied by the contents of the original documents as a whole (see T 13/83, OJ EPO 1984, 428). However, such is not the case here. Moreover interpreting Rule 88, second sentence, EPC to mean that an inadmissible extension of the contents could be allowed as a correction would also conflict with Article 164(2) EPC, which stipulates that the provisions of the Convention take precedence over those of the Implementing Regulations. The request for correction cannot therefore be allowed.

2.3 For the above reasons the application as worded in the main request does not fulfil the requirements of the EPC. Accordingly, the appellants' main request cannot be granted.

3. Re the alternative request:

3.1 Claim 1 under the alternative request differs from the corresponding, independent apparatus Claim 8 as originally filed mainly in no longer containing the feature originally claimed whereby the test apparatus has a logic circuit which controls a display for indicating the test piece's physical condition. The protection sought under Claim 1 according to the alternative request therefore now covers a test apparatus with no such logic circuit plus associated display. For the reasons given above concerning the corresponding amendment to the originally independent process Claim 1, however, such a test apparatus is neither expressly described in the original application documents nor can it be clearly inferred from them. Since the amendment to Claim 1 according to the alternative request thus also contravenes Article 123(2) EPC, the appellants' alternative request must also be refused.

ORDER

For these reasons, it is decided that:

The appeal is dismissed.