concurring.
I am afflicted with a gnawing distrust of the application of the optical theories in this case by appellant and by the majority. I concur in the result because I believe an adequate practical disclosure has been made of an operative projection system having the advantages claimed for it.
It is not customary in patent cases to require an applicant either to know and disclose the underlying theory of his invention or to hold him to an expressed erroneous theory. Eames v. Andrews, 122 U.S. 40; Robinson on Patents, § 485; In re Modine, 19 CCPA 1058, 57 F. 2d 355, 13 USPQ. 88. In principle the same would generally be true of an erroneous application of theory, I think.
This case involves a sort of chicken-and-egg situation. The acknowledged prior art set-up utilizing a wide screen with curved ends entailed, appellant says in his specification, putting the side projectors at the sides of the theater so they could shoot axially at the curved screen end sections. This put them closer to the screen than the center projector in the booth and if the end section pictures were to be the same size as the center section picture the focal length of the side projection lenses would obviously have to be shorter than that of *1082the center projector lens.1 The shorter throw of the side projectors gave their projected images a shorter depth of focus (relative to that of the center projector). But due to the screen curvature, a greater depth of focus was desirable. (Whether necessary would depend on theater size and screen curvature.) This could be achieved only by moving the projectors further from the screen and, of necessity, using longer focal length lenses, so as to retain the same picture size while doing so.
Appellant increased the distance by projecting along a dog-leg,, using a mirror at the bend. While some references show the use of mirrors and dog-leg projection, the purposes were different. The main reason why appellant did this seems to have been to get all of the projectors in the projection booth at the back of the theater and simultaneously to eliminate projectors at the side so as not to cut down the size of .the audience, without losing axial projection to the ends of the screen. The application says:
Attainment of this object automatically permits the use of long-focus lenses providing a relatively deep field of focus at the screen, whereby to provide sharpness: on the concave screen portions. [My emphasis.]
As to using “long focus” lenses, all claims state that the side projectors use long focus lens system. This does not impress me as anything remarkable. In picture projection the focal length of the lens used is determined by two factors: (1) the size of the picture desired on the screen and (2) the distance of the projector from the screen.. Appellant’s specification states, with respect to the center projector, which shoots straight at the center of the screen in a conventional manner, “The longest possible focus projection lens may be used by this projector.” A little thought will show the statement to be meaningless. Once the picture size is determined, the focal length of this, lens will be fixed by the size of the theater and the distance from its screen to the projection booth, so there is only one possible focal length. Whatever it is, if the side projectors are shooting along doglegs of greater total length than the throw of the center projector, the focal lengths of their lenses will necessarily be longer than that of the center projector. As the application says, “so the focal length, of the projection lens for the [side] projector 6 is even greater than in the case of the [center] projector 7.”
*1083“Long,” with respect to the focal length of lenses, is, in any event,, a relative term. The specification gives us no focal length of any lens. About all we know in this case is that the applicant says his center projector will have the “longest possible” focal length and that the focal length of the side projector lenses will be longer. And all of the focal lengths will be determined by theater size.
The novelty here, it seems to me, is the dog-leg-with-mirror projection from the booth into curved screen ends, preferably axially thereof, for the purpose of getting clear end pictures, or at least dearer pictures than when the side projectors shoot straight from the theater side walls axially of the the curved screen ends.
Claim 23 defines an arrangement where there is not likely to be much of an advantage, a sort of de minimis application of the appel-, lant’s scheme. How much longer the throw of the side projectors will be through the use of the mirrors will depend entirely on how big the projection booth is. (The booth is in the claim and the mirrors are in the booth.) As shown in the drawing, the optical distance for the side projectors is about 7% greater than that for the-center projector, as compared with an .increase.of about 50% in the other embodiment where the mirrors are on the theater walls. Slight though the advantage may be, I do not see any reason to deny appellant this claim.
I agree to the reversal of the rejection.
At a given distance from a screen, the shorter the focal length of the lens the larger the picture will be. Also, with a le¡ns of given focal length, the closer to the screen; the projector Is the smaller the picture will be. A picture gets larger as the projector Is moved away from the screen and If the picture Is to be kept the same size the lens must be of longer focal length as the projector is moved away and shorter focal length as the projector Is moved closer. These are some of the simple optical facts Involved In. this case.