Magnetoresistive head for reading magnetic ink characters

Claim 1

A reader for reading MICR characters on a document comprising: a substrate having first and second magnetoresistive elements thereon, with said first and second magnetoresistive elements having a width W and a gap G therebetween, with said W and G bearing a relationship to a font of the MICR characters to be read; a first resistor and said first magnetoresistive element being series connected and having a first node therebetween, with a remaining end of said first resistor being coupled to a source of potential and with a remaining end of said first magnetoresistive element being connected to a ground; a second resistor and said second magnetoresistive element being series connected and having a second node therebetween, with a remaining end of said second resistor being coupled to said ground and with a remaining end of said second magnetoresistive element being connected to said source of potential; a differential amplifier having first and second inputs and an output therefrom; first coupling means coupling said first node to said first input of said differential amplifier; and second coupling means coupling said second node to said second input of said differential amplifier.

Claim 6

A method of sensing MICR characters on a carrier which is independent of the speed at which the carrier is moved relative to a reader, comprising the steps of: (a) positioning first and second magnetoresistive sensors on a substrate, with said first and second magnetoresistive sensors having a width W and a gap G therebetween, and with said W and G bearing a relationship to a font of MICR characters to be read, said first and second magnetoresistive sensors and said substrate comprising said reader; (b) providing relative movement between said reader and said carrier; and (c) coupling said first and second magnetoresistive sensors to a full bridge circuit whose output provides a magnetic waveform of the MICR character read; said coupling step being effected through; (c-1) coupling said first magnetoresistive sensor and a first resistor in series with a first node therebetween; (c-2) coupling said second magnetoresistive sensor and a second resistor in series with a second node therebetween; (c3) coupling one end of said first resistor and one end of said second magnetoresistive sensor to a source of potential; (c-4) coupling one end of said second resistor and one end of said first magnetoresistive sensor to a ground; and (c-5) coupling said first and second nodes to a differential amplifier to provide said output.

Claim 7

A method of sensing MICR characters on a carrier which is independent of the speed at which the carrier is moved relative to a reader, comprising the steps of: (a) positioning first and second magnetoresistive sensors on a substrate, with said first and second magnetoresistive sensors having a width W and a gap G therebetween, and with said W and G bearing a relationship to a font of MICR characters to be read, said first and second magnetoresistive sensors and said substrate comprising said reader; (b) providing relative movement between said reader and said carrier; and (c) coupling said first and second magnetoresistive sensors to a full bridge circuit whose output provides a magnetic waveform of the MICR character read; said coupling step being effected through; (c-1) coupling said first magnetoresistive sensor and a first resistor in series with a first node therebetween; (c-2) coupling said second magnetoresistive sensor and a second resistor in series with a second node therebetween; (c3) coupling one end of said first resistor and one end of said second magnetoresistive sensor to a source of potential; (c-4) coupling one end of said second resistor and one end of said first magnetoresistive sensor to a ground; and (c-5) coupling said first and second nodes to a differential amplifier to provide said output.