|European Case Law Identifier:||ECLI:EP:BA:1993:T014192.19930729|
|Date of decision:||29 July 1993|
|Case number:||T 0141/92|
|IPC class:||H05F 3/02|
|Language of proceedings:||EN|
|Download and more information:||
|Title of application:||Radiation and static electricity suppression device|
|Applicant name:||DACA International B.V.|
|Opponent name:||01) Coe, Adrian Brian
02) Savio Plastica S.r.l.
03) Systemdienst Gerd Nitzsche
04) VDU Products AB
05) Cominvest System AB
06) Focus Computer Products A/S
07) Swiss-Can Agencies Ltd.
|Relevant legal provisions:||
|Keywords:||Inventive step - no|
Summary of Facts and Submissions
I. European patent No. 0 092 308. was opposed by seven opponents on the grounds mentioned in Article 100(a)EPC. A full list of the documents cited in support of the opposition is set out in an annex to the Interlocutory Decision of the Opposition Division dated 27 January 1992, in which it was decided to maintain the patent in amended form in accordance with the main request of the patent proprietor, Claim 1 of which was filed on 31 October 1991, and reads as follows:
1. "A radiation and static electricity suppression device for a cathode ray tube, comprising a conductive mesh screen (14) held in a frame (16), positionable before the curved cathode ray tube viewing surface, with means for electrically connecting the screen to the ground of the cathode ray tube to hold the screen at ground potential, wherein the frame (16) is flexible;the screen (14) is a fine mesh conductive fabric of synthetic fibres, one quarter or more of the warp and/or weft synthetic fibres are electrically conductive and said conductive fibres (22) are substantially evenly distributed in the fabric, and the device is positionable on the cathode ray tube with the frame (16) flexing to conform thereto and the screen fabric (14) contacting over the viewing surface thereof and conforming thereto over said surface in use."
Claims 2 to 9 of such main request are dependent on Claim 1.
II. According to the description of the patent, the problem underlying the claimed device is to prevent the accumulation of dust on the viewing surface of a cathode ray tube which results from static electricity, as well as to reduce electro-magnetic radiation emanating from the cathode ray tube.
The Opposition Division decided that Claim 1 of the main request was novel, in particular with respect to document:
D21:US-A-4 253 737
which is considered in the description of the patent to be the closest prior art.
Furthermore, in connection with inventive step, the Opposition Division considered that a skilled person wishing to solve the above problem would start from document:
D5:JP-UM 3 625 434
because this document is concerned with preventing dust from accumulating on a viewing surface of a cathode ray tube, and discloses a fine wire mesh screen positioned to conform with the curved viewing surface. The Opposition Division recognised that synthetic electrically conductive mesh fabrics were already known from a number of the cited documents, some of which even mention that such fabrics can be used for shielding electro-magnetic radiation. However, the Opposition Division decided that Claim 1 involved an inventive step, in particular because none of the cited documents suggested the use of a synthetic electrically conductive mesh fabric in contact with the viewing surface of a cathode ray tube (CRT), both to suppress the electrostatic field and to prevent the accumulation of dust and dirt. The Opposition Division considered that a skilled person would not have considered these materials, because nothing is stated in the cited documents to the effect that meshes made of such synthetic conductive fibres have suitable properties in the sense that they would not unduly affect the visibility of the viewing surface.
III. Four of the opponents filed appeals against the above Decision, namely the first, third, fourth and fifth opponents. In reply, the patent proprietor maintained the main request and four auxiliary requests which had been filed during the opposition proceedings.
IV. A communication was issued on behalf of the Board, accompanying a summons to oral proceedings. The communication considered the question of inventive step starting primarily from document D5. The following documents (in addition to documents D5 and D21) were cited in the communication:
D16': EP-A-0 010 712
D26: JP-B-72 014078 (Derwent-Abstracts)
D125: Catalogue of Tetko Inc.: "Industrial Screening and Filtration Media", General Catalogue 200, 1978, pages 1 to 43
D126: "The Independent Journal", 9 September 1981, Artcle "Firm a big success in computer field" By Wat Takeshita.
V. In response, the fourth and fifth opponents supported the ground of lack of inventive step starting from document D5, whereas the first opponent continued to support this ground starting from document D21, having regard also to the fact (admitted by the patent proprietor during the proceedings before the Opposition Division) that about half a million devices as disclosed in document D21 were sold before the priority date. The first opponent also filed letters from two companies (Precision Textiles Ltd. and N.V. Bedaert) in support of its submission that the ability of static electricity to attract dust and its elimination by earthing out was common general knowledge).
VI. Also in response, the patent proprietor maintained the main request, and filed eight new auxiliary requests, replacing the previous auxiliary requests, on 29 June 1993.
Claim 1 of the first auxiliary request adds to Claim 1 of the main request between "a conductive mesh screen (14) held in" and "a frame (16)" the words "and fixed to".
Claim 1 of the second auxiliary request substitutes the wording of Claim 1 of the main request "the device is position able on the cathode ray tube with the frame (16) flexing to conform thereto" by the wording "the device is positionable on the cathode ray tube with the frame flexing to conform to the display surface".
Claim 1 of the third auxiliary request adds to Claim 1 of the main request after "the screen is a fine mesh conductive fabric of synthetic fibres" the words "of anti-reflective colour"
Claim 1 of the fourth auxiliary request adds to Claim 1 of the main request between " and the screen fabric (14) contacting over the viewing surface thereof and conforming thereto" and "over said surface in use" the words "sufficiently closely to eliminate Newton's rings".
Claim 1 of the fifth auxiliary request adds to Claim 1 of the main request after "compromising a conductive mesh screen (14) the words " with 30 to 120 fibres per cm (75 to 300 fibres per inch)".
Claim 1 of the sixth auxiliary request substitutes the wording of Claim 1 of the main request after "the screen (14) is a fine mesh conductive fabric of synthetic fibres" by the wording: "one quarter or more of the warp and/or weft synthetic fibres being electrically conductive material because of an electrically conductive coat or impregnation with electrically conductive material, and said conductive fibres (22) are substantially evenly distributed in the fabric, and the device is positionable on the cathode ray tube with the screen fabric (14) contacting over the viewing surface thereof and conforming thereto sufficiently closely to eliminate Newton's rings over said surface in use."
Claim 1 of the seventh auxiliary request adds to Claim 1 of the main request after "comprising a conductive mesh screen (14)" the words "with 30 to 120 fibres per cm (75 to 300 fibres per inch)" and replaces the wording "one quarter or more of the warp and/or weft synthetic fibres are electrically conductive" by the wording "in which at least one third of the synthetic fibres are electrically conductive because of an electrically - conductive coat or impregnation with electrically conductive material".
Claim 1 of the eighth auxiliary request adds to Claim 1 of the main request after "one quarter or more of the warp and/or weft synthetic fibres are electrically conductive" the words "owing to an electrically - conductive plastic coat or impregnation with electrically-conductive material".
VII. Two days before the oral proceedings, the first opponent filed a report from the UK Patent Office Search and Advisory Service, and six further patent specifications referred to in such report, in support of its submission that it was common general knowledge in the field of cathode ray tubes that electrically conductive synthetic fibres were readily available and suitable for use in the elimination of static electricity. This report and the six accompanying patents had also been received by the patent proprietor's representatives two days before the oral proceedings, but was not received by the Board until after the oral proceedings had commenced, on 29 July 1993.
VIII. The patent proprietor and the first, third and fifth opponents were represented at the oral proceedings; the fourth opponent was not able to attend. During the oral proceedings the patent proprietor filed a chronological summary of the documents cited in the present proceedings and a diagram of an embodiment of the claimed device mounted on a CRT display surface and demonstrated inter alia an embodiment of the claimed device both on its own and mounted on a cathode ray tube.
IX. The Appellants (the first, third, fourth and fifth Opponents) all request that the decision under appeal be set aside and that the European patent No. 0 092 308 be revoked.
The Respondent (the Patent Proprietor) requests that the appeals be dismissed and that the patent be maintained as amended in accordance with the Main request as filed on 31 October 1991 or one of the Auxiliary Requests I to VIII filed on 29 June 1993.
X. In support of these requests, the first and third opponents argued in writing and orally essentially as follows:
(a) The closest prior art according to document D21 comprises all features, properties and dimensions of the device claimed in Claim 1 of the main request, except the feature that the mesh is "electrically conductive". As stated in the description of the patent in suit, column 2, lines 32 to 40, this single distinguishing feature solves the major problem of dust and dirt on the cathode ray tube due to static electricity. The reduction of electro-magnetic radiation occurs automatically and represents an advantage which is achieved simultaneously.
(b) As indicated in the patent in suit, column 1, lines 31 to 39, 43, 48 to 61, column 2, lines 5 to 10 and as established in evidence,it belongs to a skilled person's common general knowledge in the CRT-field that conductive meshes earth out static electricity for avoiding dust deposition. Thus, it is an obvious modification to replace the insulating anti-glare mesh of document D21 by a conductive one with the same optical qualities, in particular by a mesh which is available on the market and disclosed in detail in document D125.
(c) Document D125 draws to the skilled person's attention the fact that meshes of synthetic conductive fibres bleed off electrostatic charges (page 5, right column, lines 14 to 17) find a typical end use in the field of CRT display screens (page 9, right column, line 4) are elastic (page 20, left column, lines 15 to 19), have dimensions in the claimed region which are comparable with those of document D21 (table at the end of page 20) and also shield electromagnetic radiation (page 20, left column, lines 10-12). Hence, no new mesh material has been invented. A skilled person can be expected to select the appropriate stretchability for flexing, contacting and conforming to the CRT viewing surface in use. The lower limit of "one quarter" of the claimed portion of conductive fibres in the mesh is arbitrary and can moreover be found in routine treat and error experiments to give particularly desired stretchability and shielding effects.
(d) Since sales of desktop computers exploded only in 1983, there exists no longfelt need as an indication of inventive step. Comparing the Respondent's sales numbers with those of all top desk computers sold during the corresponding period, only less than 1% of all sold computers may be equipped with the claimed device.
(e) The main claims of auxiliary requests I to VI have the identical distinguishing feature over document D21 as Claim 1 of the main request. Realising a synthetic conductive fibre by an electrically conductive coating or impregnation according to Claim 1 of auxiliary request VI, or by an electrically-conductive plastic coat or impregnation as claimed in Claim 1 of auxiliary request VIII, is common general knowledge and standard practice; see in particular documents D125, page 20, D16', example 9, and D26.
Claim 1 of auxiliary request VII mainly combines features of preceding auxiliary requests.
XI. The fourth opponent supported its contention of lack of inventive step starting from document D5 in writing. The fifth opponent based its request additionally on the following main arguments presented both in writing and orally:
(a) With regard to solving the problems of glare, security, health and dust mentioned in the description of the patent under appeal, by earthing out electrostatic electricity via a fine metal mesh,the closest prior art is disclosed in document D5. Consequently, the problem underlying the patent in suit is to avoid Newton's rings and Moire patterns. This problem is solved by an improved conformity between mesh and screen. The patent discloses in column 3, lines 28-30 a metal mesh and a conductive nylon mesh as equivalent embodiments, and nowhere states that Newton's rings can be better avoided by a mesh of conductive synthetic fibres.
(b) Document D18 discloses a metal anti-glare mesh with the features of granted Claim 1. The present restriction of Claim 1 to conductive synthetic fibres was only a formal distinction in order to obtain novelty. The constructional modification of the mounting from the conventional one between two panels to the present claimed one - a mesh held in a flexing frame - does not give rise to any surprising effects and is moreover obvious in view of documents D21 and D3. Furthermore, document D126 teaches to mount a conductive plastic mesh in a flexible frame and to install it in the same way as an antiglare filter. A conductive synthetic mesh which avoids Newton's rings is also disclosed in document D16', page 4, paragraph 2.
(c) Documents D21, column 1, lines 42 to 44 and document D18, column 2, lines 60-66 give sufficient guidance about how to dimension a conductive antiglare mesh with good properties for looking through.
XII. These arguments were contested by the patent proprietor, who made essentially the following submissions:
(a) The numerous cited documents can be classified into three groups; (see the chronological summary identified in paragraph VIII above:
The first group (including document D21) discloses non-conductive synthetic meshes against a CRT- screen for anti-glare. The second group (including document D5) concerns grounded metal meshes for anti-static and anti-electromagnetic purposes. The third group is related to conductive synthetic meshes used in carpets and cloths. None of these documents discloses the use of a conductive synthetic mesh in front of a CRT-screen.
(b) Though the antiglare filter (also avoiding Newton rings) of document D21 differs from the device claimed in Claim 1 only in that its mesh is electrically conductive, there is no motive for a skilled person to vary this conventional device. A skilled person would certainly be aware, as part of his common general knowledge, of the possibility to earth out static electricity. However, it is highly speculative that the dust problem in the use of the conventional anti-glare filter would be recognised as being caused by static electricity.
(c) The list of typical end uses in document D125 mentions a CRT display screen (page 9, right column, line 4) among a large list of possible other applications, and page 36, left column, lines 22 to 24 explains that the fabrics themselves are presently serving as electronic display screens. Document D125 does not teach that any of the fabrics in this catalogue is a suitable material for placing in front of a CRT-screen, nor does it disclose that the Pe Cap-M fabric described on page 20 or any other fabric is a technical means for avoiding dust. In view of the 2% elongation of Pe Cap-M fabric in its elastic recovery (page 20, right column. line 21) and the low elasticity of its metal coating, a skilled person would doubt whether this material conforms to a CRT screen. None of the fabrics in document D125 are equivalent to the one disclosed in document D21. Such fabrics are not known either in the same field or in a neighbouring field to the antiglare screen of document D21.
(d) Documents D21 and D125 disclose incompatible subject-matter. There was nowhere in the prior art a hint to combine an antiglare means and an antistatic means in one device. An antiglare mesh before a CRT screen consisted of nylon and an antistatic mesh before a CRT screen of metal. The inventive idea is to use a fibre which is both synthetic and conductive, which produces conformity to the screen as an unexpected effect, and fits easily to the CRT screen as a further advantage. When starting from the antiglare device of document D21, there is no reason why a skilled person in real life would think of combining documents D21 and D125. The long period in which no use was made of conductive synthetic meshes as a combined antiglare and antistatic means, represents a time factor supporting the contention that such use was not obvious; (see Decision T 507/89 point 7.5, last paragraph).
(e) The antistatic metal device of document D5 cannot be realised, has no frame, is not pressed against the screen surface, stays in permanent form and has a mesh too coarse to prevent glare; the expression "fine" in document D5 being a relative term. The touch pen device of document D126 has 1cm intervals between fibres and thus represents a different technical means.
(f) Whichever document is considered to constitute the closest prior art, the opponents' require a combination of at least three documents to make out their case of lack of inventive step, which is not permissible.
(g) The subject-matter of Claim 1 of auxiliary request V combines the optimisation of the antiglare properties with an increased speed for removing electrostatic electricity. The mesh of synthetic fibres with an electrically-conductive plastic coat as claimed in Claim 1 of auxiliary request VIII is not obvious in view of the fibres disclosed in document D26, because this document discloses no advantageous fibre properties which would motivate their use.
XIII. At the conclusion of the oral proceedings, the decision was announced that the decision of the Opposition Division is set aside and that European patent No. 0 092 308 is revoked.
Reasons for the Decision
1. Admissibility of late-filed evidence from the first opponent
Although these oppositions commenced in 1989, further evidence as identified in paragraph VII above was filed two days before the oral proceedings on 29 July 1993. The filing of such evidence at such a late stage in the proceedings is contrary to procedural principles and unfair to an opposing party. The evidence does not add anything relevant to what is already in the case, and is accordingly held inadmissible.
2. Inventive Step Claim 1 main request
2.1. In view of the desired properties of the device claimed in Claim 1, in the Board's opinion, the non-conductive anti-glare device disclosed in document D21 forms a relevant starting point and can thus be considered as the closest prior art. From document D21 there is known in the wording of Claim 1 of the main request:
"A ..... device for a cathode ray tube (see D21, 12 in Fig 1) comprising a .... mesh screen (18) held in a frame (20; col. 2, lines 17 and 18), positionable before the curved cathode ray tube viewing surface, .... wherein the frame is flexible (abstract, lines 5 to 7); the screen is a fine mesh...... fabric of synthetic fibres (column 2, line 15), .... and the device is positionable on the cathode ray tube with the frame flexing to conform thereto and the screen fabric contacting over the viewing surface thereof and conforming thereto over said surface in use (column 2 lines 24 to 27),"
2.2. The closest prior art already avoids Newtons's rings: see D21, column 2, lines 27 to 31. Therefore, starting from document D21, the objective problem underlying the claimed invention is to decrease the accumulation of dust and dirt on the cathode ray tube as recognised in the patent in suit. Dust and dirt diminish the optical quality of the images produced on the CRT-screen, and this disadvantage can easily be noticed in practice. Whenever a problem consists solely of eliminating deficiencies in an object which come readily to light when it is in use, the posing of such new a problem does not represent a contribution to the inventive merits of its solution; e.g. Decision T 109/82, OJ EPO 1984, 473.
2.3. Reducing electro-magnetic radiation which emanates from the CRT-screen, and which is disclosed as a further aim in the patent in suit column 2, lines 37 to 40, is known from document D16. Health hazards caused by static electricity (referred to the patent in suit column 1,lines 48 to 61), represent a well-known problem which is within the knowledge of the relevant skilled person.
2.4. The above problem is solved according to the wording of Claim 1 in that:
(a) the "fine mesh..... fabric of synthetic fibres" in the device disclosed in document D21 is replaced by a "conductive" one, wherein "one quarter or more of the warp and/or weft synthetic fibres are electrically conductive and said conductive fibres (22) are substantially evenly distributed in the fabric," and
(b) "means for electrically connecting the screen to the ground of the cathode ray tube "are provided" to hold the screen at ground potential".
Measures (a) and (b) automatically change the conventional antiglare device into the claimed anti-glare and anti-static electricity device,"
3. When assessing inventive step in accordance with the problem-and-solution approach, the question to be considered is whether it would have been obvious to the relevant skilled person, at the priority date of the patent in suit, when seeking to solve the objective problem underlying the claimed invention, to progress from the closest prior art to the claimed invention. With reference to the patent proprietor's submission in paragraph XII above, in any particular case it may be permissible to add the disclosures of one or more documents to that of the closest prior art document in order to solve the objective problem, if it would have been obvious for the relevant skilled person to make such a combination: in particular if the teaching of such documents contributes technically to the solution of the objective problem. This may be dependent, for example, upon the nature of the documents under consideration.
4. As set out in paragraphs X(b) and X(d) above, the patent proprietor submitted that it was speculative whether a skilled person would recognise the connection between the accumulation of dust and the presence of an electrostatic field, and that there was no logical reason why such skilled person would think of avoiding the accumulation of dust by using a conductive screen to earth out the static electricity. However, in the Board's view the association of dust with static electricity is part of everyday knowledge and part of the common general knowledge of the relevant skilled person, as is established by the cited documents which refer to this association (see for example, the patent in suit, column 1,line 62 to column 2, line 4, and D18). When using a device as disclosed in document D21, both the accumulation of dust and the presence of static electricity would be readily noticeable, and a skilled person could be expected as a matter of logical development to attribute the accumulation of dust at least in part to the presence of static electricity, and consequently would proceed to the consideration of appropriate means for earthing out the static electricity.
4.1. The essential modification of the closest prior art, in order to arrive at the claimed invention, is measure 1.4(a), i.e. replacing the insulating synthetic fine mesh by a conductive one. Although, as submitted by the Respondent, it is true that the prior art documents do not suggest that an anti-glare means and an anti-static means should be combined into one device, nevertheless in the Board's view a skilled person seeking to solve the above objective problem would not be limited to the consideration of how to add anti-static means to the anti-glare means disclosed in document D21. He would not wish to use two separate devices if it is foreseeable that the properties which he is seeking can be achieved in one device. The relevant skilled person is expected to have basic general knowledge in electrical engineering. Therefore, without inventiveness and merely by using his normal level of skill and knowledge, the skilled person would arrive at the idea that the simplest way to solve the above problem would be to make the mesh of document D21 electrically conductive, so as to earth out the static electricity. The Board cannot see any technical incompatibility in replacing an insulating synthetic mesh screen by a conductive synthetic one. Thus the skilled person would be interested in seeking a suitable conductive mesh material.
In this context document D125 can be considered as a very relevant guide to the various conductive mesh materials that were available to the skilled person at the priority date.
4.2. When selecting the appropriate fabric in document D125, the competent person is guided by the mesh dimensions disclosed in document D21 for maintaining the existing antiglare and transparency properties of the device which he intends to improve. In the Board's view, it is not particularly difficult to verify that the preferred mesh data disclosed in document D21, column 1, lines 42 to 44 (i.e. 67 microns fibre diameter and 50 fibres per cm) are best met by the approximately same values of the PeCap-M fabric disclosed in document D125, page 20. Contrary to the submissions in paragraphs III and X (c) above, the Board regards a skilled person as able to conclude from the comparable dimensions of both meshes that the synthetic conductive meshes of document D125 are transparent so that a skilled person will at least be motivated to test this fabric. The provision of a ground connection for the mesh screen as in measure 1.4(b) above is only a self-evident implementation of the known effect of the fabric dissipating static charges as stated in document D125, page 20, left column, line 12.
4.3. The claimed effect of conformity of screen and frame to the viewing surface is already achieved in the antiglare device of document D21 and would be maintained in a device provided with a fabric of document D125. Document D21 was published only one year before the priority date of the patent in suit. A period of one year for a further technical development of an antiglare filter appears to the Board as normal and cannot be considered as a time factor evidencing a non-obvious use of the fabrics of D125; see paragraph X-d above.
4.4. The alternatives in measure 1.4(a) of Claim 1 wherein only a certain part of the insulating synthetic fibres of the mesh in either the warp, the weft or both is replaced by conductive synthetic fibres, are known from document D125, page 25, left column, lines 12 to 19, The original documents of the patent in suit contain no information that within the claimed region of "one quarter or more of the warp and/or weft synthetic fibres being electrically conductive" any particular unexpected effects occur, so that the particular values of the lower limit of the conductive fibre content can only be considered as the result of an obvious arbitrary selection;see also Decision T 198/84, OJ OEB 1985, 209.
4.5. In the Board's view, because of the necessary vacuum in a cathode ray tube it is improbable that a skilled person would interpret the teaching of document D125, page 36, left column, lines 22 to 24: ".... fabrics are presently serving as electronic display screens" in combination with the use stated on page 9, right column, line 4: "CRT display screens" as suggesting that the mesh fabrics of document D125 themselves shall be used as CRT-screens. In the Board's view it is generally known that electrostatic charges are located on the screen surface. Therefore it would be natural for a skilled person to bring the conductive mesh fabric in contact with the screen surface. The incomplete elastic recovery put forward by the Respondent in paragraph XII(c) would only be a disadvantage after a first removal of the device from the screen. However, the patent in suit does not suggest how to overcome such a disadvantage.
4.6. In the Board's judgment, for the reasons indicated in detail in paragraphs 1.1 to 1.6 above, the subject- matter of Claim 1 of the main request is an obvious use of the known properties of a known fabric for a known technical purpose accompanied by an adaptation measure and a dimensioning rule which both fall within the normal ability of the skilled person. Therefore, in the Board's judgement Claim 1 of the main request lacks an inventive step within the meaning of Article 56 EPC.
4.7. Having regard to this finding, it would be superfluous for the Board to consider whether the subject-matter of Claim 1 of the main report also lacks an inventive step if document D5 is considered as the closest prior art.
5. Claims 2 to 9 of the main request fall because of their dependence on Claim 1.
6. Inventive Step: Claims 1 of auxiliary requests I to VIII
6.1. The supplementary feature in Claim 1 of the first auxiliary request, i.e. that the screen "is fixed" to the frame, is disclosed in document D21, Fig 3 and col 2, lines 16 to 19.
6.2. The specification in Claim 1 of the second auxiliary request, i.e. that the frame is flexing to conform "to the display surface" is disclosed in document D21, col 2, lines 24 to 27.
6.3. The feature added in Claim 1 of the third auxiliary request, i.e. that the fibres are of "anti-reflective colour" is disclosed in document D21, col. 2, lines 14 to 16.
6.4. The functional feature additionally claimed in Claim 1 of the fourth auxiliary request, ie. that the fabric conforms to the viewing surface "sufficiently closely to eliminate Newton's rings " is disclosed in document D21, col. 2, lines 24 to 31.
6.5. The mesh dimensions added in Claim 1 of the fifth auxiliary request, i.e. 30-120 fibres per cm (75 to 300 fibres per inch), are obvious in view of the disclosure, namely 75-150 fibres per inch, in document D21, col.2, lines 22 and 23. An increased speed for removing static electricity due to the claimed range of dimensions (paragraph XII-g) is not disclosed in the patent under appeal.
6.6. The realisation of the conductivity of the synthetic fibres by "an electrically conductive coat or impregnation" according to Claim 1 of the sixth auxiliary request is disclosed in document D125, page 20, left column, lines 2 to 4 or in document D16, page 20, lines 6 to 20 respectively.
6.7. Claim 1 of the seventh auxiliary request combines the features added in Claims 1 of the fifth and sixth auxiliary request and modifies the lower limit of the conductive fibre content to "one third" as a result of an arbitrary selection; see also paragraph 1.6.1 above.
6.8. The realisation of the conductivity of the synthetic fibres by "an electrically-conductive plastic coat" "according to Claim 1 of the eighth auxiliary request is disclosed in document D26, which -contrary to the Respondent's view in (paragraph XII-g) - belongs to the field of the competent specialist for the reasons stated in paragraph 4.1 above. Due to the fact that the patent under appeal does not disclose any particular advantages of such fabric, its use as an alternative to the ones disclosed in document D125 represents an obvious exchange of equivalents.
6.9. The additional features of Claims 1 of the auxiliary requests, as discussed in paragraphs 6.1 to 6.8 above, are thus known or are obvious, and their incorporation in the claimed subject-matters does not go beyond the normal activities of a person skilled in the art. Hence, Claims 1 of auxiliary requests I to VIII are considered to lack an inventive step within the meaning of Article 56 EPC.
For these reasons, it is decided that:
1. The Decision of the Opposition Division is set aside.
2. European patent No. 0 092 308 is revoked.