Browse Prior Art Database

Hand Fed Card Reader

IP.com Disclosure Number: IPCOM000078825D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 4 page(s) / 83K

Publishing Venue

IBM

Related People

Hobbs, JN: AUTHOR [+2]

Abstract

Fig. 1 illustrates the structure for a punched data card reader, utilizing optical sensors to detect holes and webs between holes. The reader is very Inexpensive in that it is simple and is a hand-fed device, in Which no transport mechanism is used to move the card past the sensor position. Since the speed with which the card will pass the sensors varies in a hand-feed operation, special circuitry has been included to overcome the effects of speed variations and to assure that accurate reading is accomplished.

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Hand Fed Card Reader

Fig. 1 illustrates the structure for a punched data card reader, utilizing optical sensors to detect holes and webs between holes. The reader is very Inexpensive in that it is simple and is a hand-fed device, in Which no transport mechanism is used to move the card past the sensor position. Since the speed with which the card will pass the sensors varies in a hand-feed operation, special circuitry has been included to overcome the effects of speed variations and to assure that accurate reading is accomplished.

A long-filament lamp 1 provides a source of illumination for the array of phototransistors 2 mounted on circuit card 3, which is positioned above the upper card guide 4. Card guide 4 has a number of holes 5, which are approximately a quarter of an inch deep and 0.035" in diameter. Holes 5 are countersunk to accept the lens for each phototransistor 2. Using holes of this size in this assembly makes additional shielding and focusing of light source 1 unnecessary, since the long-filament lamp provides even illumination across the width of a card to be read. A mechanical card stop 6 is, as shown, attached to the lower card guide 7 in a position which will stop a card with enough of a card left protruding from the reader to allow an operator to grasp a card.

Fig. 2 illustrates a block diagram for the electronic circuitry and logic control for the reader. Signals coming from individual phototransistors 2 are amplified in the photoamplifier 8, and detected as discrete levels by the Schmitt trigger 9. A positive output level from Schmitt trigger 9 is indicative that light is being sensed by the phototransistor 2, which indicates either that no card is in the reader or a hole is present under that position in which the phototransistor is located. The positive output is inverted in the inverter 10 for storage in data register flip-flop sections 11.

A sequence of operations which occurs during normal read operation is as follows: with no card in the reader, positive outputs will be produced by all Schmitt triggers 9, designated in this case in BCD code format as +1 bit, +2 bit, +4 bit, and +8 bit. These outputs are applied to AND gate 12 and decoded as the "card out" signal which, applied through latch 13, OR gate 14, and inverter 15, holds the cells in the data register 11 in a reset condition. When a card is inserted, the leading edge of the web of the card blocks light from all of the phototransistors 2, which causes the "card out" signal from AND gate 12 to be dropped. The "web decode" signal will then be produced by the negative outputs appearing from the inverters 10 which are applied to AND gate 16 which, in turn, reconditions latch 13 and removes the reset condition from data register 11. When the first column of punched positions in the card passes under the reader sensors, the bits that are sensed by the phototransistors are set into the data register 11.

Whenever any bit is set in any cell in the data re...