T 0867/06 23-03-2009

Reasons for the Decision

1. The appeal is admissible.

Main request - Inadmissible extension

2. Claim 1 of the main request differs inter alia from claim 1 of the application as originally filed by the additional feature "the output voltage of each of said first and second voltage sources (30, 31) can be set arbitrarily in order to set an input range of the AD converter" (emphasis added by the Board). This added feature covers setting the output voltage of the first source and the output voltage of the second source independently from each other and extends beyond the content of the originally filed application for the following reasons.

2.1 The ?? type AD converter according to claim 1 of the main request has to be understood as comprising one local D/A converter with one output because this claim specifies "means (28; 47) for varying the output of said local D/A converter". The first example of converter described in the original application with reference to figure 1 is the only one which comprises one local D/A converter with one output (the output of the switch 29) and can provide a support for claim 1. It appears from the passages of page 3, lines 5 to 8; page 8, lines 2 to 4, 15 to 18 and 20 to 23 of the original description, that the terms "input range" and "conversion range" refer in the context of the invention to the same range of signals, and that the input range, i.e. the conversion range, of the ?? AD converter can be set arbitrarily by arbitrarily setting the voltage(s) of the reference voltage sources 30 and 31. However, the part of the description relating to the first example of converter neither states, nor is it directly and unambiguously derivable from it, that an output voltage of the first source and an output voltage of the second source can be set independently from each other.

2.2 More specifically, even if the description specifies in general that the input range of the first example of converter can be set arbitrarily, there is no specific disclosure that the voltage of each source 30, 31 can be set arbitrarily. Furthermore, the original application does not mention what kind of signals are inputted to the converter so that it is not possible to derive from the "setting of an optimal conversion range depending upon the input signal" (page 8, lines 20 to 23) that the first and second source voltages can be set independently from each other. Therefore, the amendments made to claim 1 of the main request contravene Article 123(2) EPC.

Auxiliary request I - Lack of novelty

3. Document D4 discloses an ?? type AD converter which comprises all the features specified in claim 1 of the auxiliary request I:

3.1 D4 explicitly discloses (figure 2; column 4, line 58 to column 5, line 24):

- a local D/A converter 208 having at least a first output voltage level and a second output voltage level (reference voltages +V(t) and -V(t)); an integrator 203 integrating a difference (differential summer 202) of an input signal and an output of said local D/A converter 208;

- a comparator 206 comparing the outputs of said integrator 203 (a direct coupling of the comparator with the integrator output is not required by the claim);

- means (switch 208) for varying the output of said local D/A converter depending upon an output of said comparator 206; and

- switching means 208 for switching said first output voltage level +V(t) and said second output voltage level -V(t) of said local D/A converter 238.

3.2 A first voltage source for outputting the first output voltage level +V(t) and a second voltage source for outputting the second output voltage level -V(t) are necessarily provided in D4 for generating the reference voltages +V(t) and -V(t), even if said voltages have the same magnitude (absolute value).

3.3 In D4, the reference output voltages +V(t) and -V(t) are set in order to adapt an input range of the AD converter to the time-varying input signals. As the original application (see page 3, lines 5 to 8) specifies that the converter "can arbitrarily set conversion range to permit setting of an optimal conversion range depending upon the input signal", no difference can be seen between the arbitrary setting of the source voltages specified in claim 1 and the setting of the reference voltages of D4. Furthermore, the last feature of claim 1 cannot be understood as restricted to output voltages of first and second sources which are set independently from each other (see supra 2.1 and 2.2). The claimed output voltages are thus anticipated by the reference voltages V(t) and -V(t) disclosed in D4, even if these reference voltages have the same magnitude.

Accordingly, the subject-matter of claim 1 according to the auxiliary request I lacks novelty (Article 54 EPC).

Auxiliary request Ia

4. Claim 1 of the auxiliary request Ia differs from claim 1 of the auxiliary request I in that the term "conversion range" is amended to "an input range and a conversion range". The terms "input range" and "conversion range" have the same meaning in the context of the invention, as appears for instance from page 3, lines 5 to 8 (see supra 2.1 and 2.2). Thus, the amendment made to claim 1 of the auxiliary request Ia introduces in the claim redundant terms which render the scope of the claim unclear (Article 84 EPC). Moreover, the subject-matter of claim 1 of the auxiliary request Ia, which covers a converter identical to the one specified in claim 1 of the auxiliary request I, lacks novelty for the foregoing reasons (supra 3 to 3.3).

Auxiliary requests II and IIa

5. The ?? AD converters specified in the set of independent claims 1 to 4 as originally filed all comprise an integrator, which integrates a difference of an input signal and an output of a local D/A converter, and means for varying the output of said D/A converter. By contrast, claim 1 of the auxiliary request II relates to a ?? AD converter which comprises two integrators 38 which integrate a difference of an input signal and each output of the local D/A converter. Thus, claim 1 of the auxiliary request II seems to be based on the second and third embodiments described in the application with reference to figures 2 and 4 and to include at least a feature, i.e. a second integrator, which is not specified in the original claims. Moreover, the search report has not been drawn up for the original independent claims 2 to 4 which were considered lacking unity. In the circumstances, it is not clear to the Board whether claim 1 of the auxiliary request II relates to searched or unsearched subject-matter.

6. According to Rule 137(4) EPC 2000, amended claims may not relate to unsearched subject-matter which does not combine with the originally claimed invention or group of inventions to form a single general inventive concept. Moreover, an applicant who fails to pay the further search fees for a non unitary application cannot pursue that application for the subject-matter in respect of which no search fees have been paid (G 2/92, OJ 1993, 591). Accordingly, the Board is not in a position to decide whether the subject-matter specified in the auxiliary request II can be pursued in the present application. In any case, claim 1 of auxiliary request II includes substantial amendments which require further substantive examination. The same considerations apply to auxiliary request IIa. In such circumstances, the Board finds it appropriate to remit the case to the department of first instance for further prosecution (Article 111(1) EPC).

7. The Board notes that the examining division has not examined whether the objection of lack of unity raised by the search division was well founded. In order to avoid a possible misunderstanding, the Board wishes to make clear that it has not examined whether the original application does comply or not with the requirement of unity of Article 82 EPC, as objected by the search division. The Board has also not examined whether the claims of auxiliary requests II and IIa comply with the requirements of Article 123(2) EPC.