Patent GB-867049-A (GB)
Title: Improvements in or relating to data checking apparatus
Inventor: KEEN ALBERT JOHN
IPC: G06K5/00
Filed: 1958-10-16
Abstract: 867,049. Statistical apparatus; magnetic data-storage apparatus. INTERNATIONAL COMPUTERS & TABULATORS Ltd. Oct. 16, 1959 [Oct. 16, 1958], No. 33044/58. Class 106 (1). Apparatus for sensing record cards or the like upon which data is recorded by one hole (or mark) in each column has means for detecting the presence of blank columns or columns having more than one hole comprising for each column a magnetic core which is normally in the unset state, there being core resetting and core setting means made operative in sequence upon the sensing of a hole, a second hole in a column thereby causing the core to unset and generate an error signal. The core 8 for one column is shown dotted in four separate positions, linked with each of its four windings 9, 10, 11 and 12. The sensing brush 7 for each column is connected through a resistor 19 and winding 9 to a capacitor 20, the other side of which is connected by cam-contacts 21 at each index time to positive supply 50 and by cam-contact 22, diode 24 and resistor 23 back to winding 9. If a hole is sensed by brush 7 capacitor 20 is allowed to charge through winding 9. Immediately after sensing each index position contacts 21 open and contacts 22 close so that if there was a hole the capacitor discharges, the current now passing in reverse through the winding 9. The charging of the capacitor drives the core to the unset state and the discharging sets it. After all positions have been sensed the core is tested to determine whether a hole has been sensed. For this purpose a winding 10 is pulsed in both directions successively by the closing of camcontacts 25 and 27 to charge and then discharge capacitor 26. The first operation sets the core if it is not already set by the sensing of a hole by brush 7, and the second resets it. The output windings 11 and 12 provide error signals as follows. The winding 11 causes a positive pulse to pass through diode 29 when the core is reset from the set state, this pulse being applied through capacitor 30 and a gating diode 33 to the grid of valve 32. The connection between the diode 33 and capacitor 30 is raised by the closing of cam-contacts 28 during the whole of the sensing period, thereby enabling the gate. If a pulse is delivered from winding 11 at any time during this period the bias of the valve 32 is overcome and an error signal appears on lead 40. This circuit accordingly responds to the presence of a second hole in the column, the resetting of the core by the sensing of the second hole, causing winding 11 to give an output. Winding 12 is similarly connected but the controlling cam-contacts 41 close after the sensing operation, during the period of operation of contacts 25 and 27. If there is no hole in the column the core is not set during the sensing period but is set by closure of contacts 25 immediately after. This causes winding 12 to provide a positive pulse whose effect is identical to that of winding 11. In modifications the record may be a tape, the holes or marks may be sensed photoelectrically or magnetically if the record is magnetic (e.g. magnetic tape or disc). All positions of a record may be sensed simultaneously, the index positions being serialized by a commutator. Specification 555,995 is referred to.