Photointerrupter driving circuit capable of decreasing the number of parts
AssigneeMitsumi Electric Co., Ltd.
InventorsAkira Shibata, Yoshihito Otomo, Koichi Seno
Life of this patent
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Abstract
In a photointerrupter comprising a light emitting diode and a photo transistor which are opposed to each other, the photo transistor has an emitter which is grounded through a resistor while the light emitting diode has a cathode which is connected to an input terminal of a one IC chip for controlling a flexible disk drive. The one IC chip incorporates a constant current source which is connected to the input terminal through an npn-type bipolar transistor. The one IC chip incorporates a logic circuit having an output terminal which is connected to a base of the npn-type bipolar transistor.
Claims3
A photointerrupter driving circuit for use in a flexible disk drive for driving a flexible disk having a magnetic recording medium loaded therein, wherein said photointerrupter driving circuit is for driving a photointerrupter for use in detecting a position of the most end track of the magnetic recording medium of said flexible disk, said photointerrupter comprising a light emitting diode and a photo transistor which are opposed to each other, the light emitting diode having an anode connected to a power supply terminal while the photo transistor has a collector connected to the power supply terminal, said photointerrupter driving circuit comprising:
- a resistor coupled between an emitter of said photo transistor and a grounding terminal;
- and
- an integrated circuit having an input terminal connected to a cathode of said light emitting diode, said integrated circuit being for controlling said flexible disk drive, said integrated circuit incorporating a constant current source which is connected to the input terminal through switching device.
Dependencies are inferred from the claim text.