Patent GB-502560-A (GB)
Title: Improvements in and relating to calculating apparatus
IPC: G06E1/04
Filed: 1937-06-18
Abstract: 502,560. Photo - electric calculating apparatus. LANNERT, A. June 18, 1937, No. 16996. Convention date, July 20, 1936. [Class 40 (iii)] [Also in Group XIX] An electrical calculating machine comprises, for each denomination, a pair of electrical measuring instruments so arranged that the first instrument receives a current value corresponding to the numerical value set up and transmits a value depending thereon to the second instrument, the second instrument, in turn, transmitting its value back again to the first instrument, the said instruments being alternately held in the set position. In the form shown, the electrical transmission comprises photo-electric means and rotatable perforated plates for producing the light impulses. Each denomination, three of which are shown in Fig. 2, comprises a bank of keys a, b, sources of light i, o, r, rotatable perforated discs k, p, s and u photo-electric cells l, q, t and v, and measuring instruments such as ammeters c, d. The discs are rotated at a uniform speed and the perforations are arranged in circles, the number depending on the value of the digits as shown in Fig. 8. When a key is depressed, a ray of light is deflected through the appropriate circle of holes to the photoelectric cell l and the current impulses generated are transmitted to the instrument c. The instrument c is held in adjusted position and carries a screen with an aperture m through which light from the source o is deflected on to the disc p which influences the photo-electric cell q to transmit current impulses to the second instrument d. The instrument d is then hold in its adjusted position and the instrument c is released and restored to normal. The instrument d through an aperture in its screen transmits light impulses from the source r, through the disc s, to the photo-electric cell t which transmits the value back to the instrument c. Depression of a key subsequently in the same bank effects the addition of its value to the setting of the instrument c in the same manner. If a transfer to the next higher denomination is necessary, the units value will be retained in the instrument c and a perforation n in the screen will permit a light ray to pass through the disc u to the photo-electric cell v to add a unit to the instrument c<1>, of the next higher denomination. The holding means for the instruments c, d, as shown in Fig. 7, comprise notched discs 6, 7 on their spindles with which co-operate pawls 9, 10 rotatable on a common spindle and forced apart by a compression spring 11. A time relay 12, regulated in accordance with the setting period of the instruments, actuates a fork 13 which operates the pawls 9, 10. A form of screen to permit the transmission of values to the instrument d and to the instrument c<1> of next higher denomination is shown in Fig. 9. The screen comprises a cylinder 16 with a series of holes m and slits n; the holes m allow light to pass from the source o in accordance with the units value of the corresponding range of tens values while the slits n deflect light to the disc u, Fig. 2, in accordance with the tens value to be transferred. A screen 17 ensures the transmission of a narrow ray of light instead of a broad band. Subtraction may be carried out by reversing the direction of the current through the photo-electric cells l, l<1>, and l<2> and v, v<1> and v<2>. Multiplication may be carried out by deflecting the light through holes in the discs corresponding to one factor and amplifying the current passed on by the photo-electric cells in accordance with a digit of the other factor. If the electrical instruments are constituted as watt meters, the coils can be arranged to receive impulses in accordance with the factors. In another form, multiplication can be effected by repeated addition by impulses received from a rotatable contact drum. Division is carried out by repeated subtraction. When one digit of the quotient has been calculated, the next digit is sought for by a changeover arrangement comprising a system of mirrors 33<1> arranged on the instruments, a set of fixed mirrors 34<1> and a photo-electric cell 38. The cell 38 acts upon a relay to deflect the divisor to the next lower denomination. The Specification as open to inspection under Sect. 91 comprises also an arrangement wherein the electrical measuring instruments for the various denominations are arranged around a common axis. The Specification states that a single perforated disc and a single photo-electric cell will suffice for this arrangement. This subject-matter does not appear in the Specification as accepted.