Patent GB-425474-A (GB)
Title: An improved apparatus for investigating, correcting and developing the power of human vision
IPC: A61B3/00
Filed: 1933-09-06
Abstract: 425,474. Sight - testing apparatus. SIMPKINS, R. B., 13, Holly Road, Edgbaston, Birmingham. Sept. 6, 1933, No. 24646. [Class 97 (i)] [See also Group VI] Apparatus for testing vision and exercising the eyes comprises a rod or bar c, Fig. 1, of rectangular or, (as shown), of circular crosssection having adjustably clamped at one end face-locating means comprising a graduated strip b bent to the shape of the nose and forehead and carrying a cross-strip a engaging the forehead ; alternatively, the strip may be bent upon itself and be shaped as a chin-rest, the cross strip engaging the face beneath the lower lip. The bar c carries a handle e or means for mounting it telescopically on a stand, and has mounted upon it a slidable carrier f, which, for a rectangular bar, is clampable by a set-screw engaging a flat-spring contacting with the bar, or, as shown, incorporates a ball-race f the balls f<2> of which engages longitudinal grooves c<1> in the bar. The carrier f has a handle f<3> and circular and rectangular sockets f<4>, f<5> to receive testing and exercising apparatus ; the bar c may have equidistant holes c<2> to receive such apparatus independently of the carrier. Extension pieces may be fitted to the bar. Fig. 6 shows a carrier i permitting arcuate and lateral movements of exercising apparatus and comprising a bar slidable in a clamp i<1> having a pin i<2> rotatably engaged by the socket f<4>, the bar carrying sockets i<4> which may be slidably mounted in undercut grooves. The following exercising or testing apparatus may be inserted into the sockets f<4>, f<5> or i<4>. (i) A focusing disc comprises a central black spot surrounded by a white ring itself surrounded by a black annulus. (ii) Such a disc may also be mounted on a screw for longitudinal adjustment on a bracket fitting behind an annulus also carried by the bracket. (iii) A curved bar mounted on a central spindle carried by a rod support, to rotate in a vertical plane, has attached to it two focusing discs carried on clampable sliders on the bar. (iv) A ball carrying focusing spots is suspended as a pendulum from an upstanding bracket arm which according to its position on the bar permits longitudinal or lateral swinging of the pendulum. (v) For astigmatic tests and exercises a domed disc p, Fig. 10, with a stem p<1> fitting the socket f<5>, has rotatably mounted on it a smaller disc p<2>. The disc p is marked with symmetrically arranged groups of radial lines p<6> and the disc p<2> with a pair of such groups p', mutually at right angles, and a single line p<8> symmetrical therewith. Finer graduations surround the disc p<2>. (vi) A focusing disc is mounted on a clampable slider, on a bar secured diametrically to a disc rotatable on a rod fitting ; the focusing disc carries a handle by which it can be caused to revolve in a circle of any chosen radius. (vii) A focusing disc is so mounted in a tube as to be withdrawable to any given distance within the tube to vary the illumination of the disc. (viii) A test chart, Fig. 14, comprises a domed disc t having a rod support t<1> and provided with a black surface marked in white with letters or numerals arranged at the points of intersection of broken circular and radial lines. (ix) A rectangular plate supported vertically on a rod fitting has inturned flanges on three edges for holding test or exercise cards, or a mirror ; the plate may be made inclinable on its support. Colours may be employed instead of black and white for marking the appliances. Specifications 425,521 and 425,574 are referred to.