1. A lens arrangement, suitable for looking through pinholes comprising a converging eyepiece type lens apparatus used without a conventional objective lens and arranged such that the lens arrangement projects a "virtual" aperture to a point in object space beyond a first end of the lens arrangement, said first end being the end of the lens arrangement closest to the subject being viewed, such that the virtual aperture limits the pencil of rays passing into the lens arrangement, wherein the lens arrangement contains no integral physical lens stop.There are a number of obvious problems with this claim, one of which is clarity. Following rounds of correspondence with the examiner, the claim was amended to read:
1. A lens arrangement, adapted for looking through a remote pinhole comprising a plurality of lens elements designed and configured to operate without the presence of an integral physical lens stop, such that in use the lens arrangement defines a “virtual aperture” in a pre-determined plane in object space remote from a first end of the lens arrangement, said first end being the end of the lens arrangement closest to the subject being viewed, wherein the virtual aperture acts as a remote entrance pupil in object space beyond the first end of the lens arrangement and defines a pencil of rays that passes through the lens arrangement.The examiner considered that, even after amendment, there was too much free beer in the claims. He maintained objections that the claimed invention was unclear and was not supported by the description because the claims defined the invention in terms of the result to be achieved (i.e. a stopless lens) rather than the technical features of the lens arrangement that achieved the result, and the embodiments described did not support such a broad claim. The applicant did not manage to overcome the objections, and the matter went before a hearing officer at the IPO.
As a result, the apparatus claims did not define the invention sufficiently to avoid reading directly on to an already known telescope eyepiece. The fact that the claims indicated that the lens arrangement was adapted for looking through a remote pinhole only specified how the lens arrangement could be used in practice, but did not distinguish the arrangement over a conventional telescope eyepiece. Specifying that the arrangement was designed and configured to provide the desired effect would, following Kirin-Amgen, only be allowable if the product itself was novel and inventive. The claimed invention did not therefore meet the requirements of section 14(5)(a) and (b) in that it did not define the invention and was not clear.
Although the claims in the form discussed were not allowable, the hearing officer allowed the applicant another opportunity to submit further amendments by extending the compliance period. As of today, it looks (thanks to the IPO's Ipsum file inspection service) like the application is still not quite finished.
As far as I can see, the lesson to be learned is to be careful with relying on functional definitions unless you have plenty of backup definitions that are more grounded in technical features of the invention. It is probably not enough to have a myriad differently defined specific embodiments unless you have some overarching technical definitions to tie at least some of them together because the only option you might end up with could be a single narrow one. It is easy with hindsight to see this being a problem; the clever trick is to spot it in advance.