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A "NO STRIPE" OPTICAL PAPER PATH SENSOR FOR TRANSPARENCIES AND PAPER

IP.com Disclosure Number: IPCOM000025663D
Original Publication Date: 1987-Feb-28
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 107K

Publishing Venue

Xerox Disclosure Journal

Abstract

Some copiedprinters use optical interrup sensors to detect the presence or absence of a sheet or transparency. Ordinarily, in the case of a transparency, a white stripe along a side of the transparency is sensed. This stripe is known to be an inconvenience to machine operators. Therefore, a device as shown in the Figure is disclosed which allows detection of transparencies which have no white stripe by the use of a reflective optocoupler type detector. The device consists of a light emitting diode (LED) and a Darlington photo detector (PD) mounted side-by-side in an injection molded package. Operation of the device is shown schematically in the Figure where light emitted from the LED is directed out away from the PD detector and in the absence of any refletive surface in front of the optocoupler gives no signal. As a reflecting surface is moved in front of the optocoupler, light from the LED is reflected into the PD and results in a photocurrent which is converted into a voltage by dropping across a resistor.

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XEROX DISCLOSURE JOURNAL

A "NO STRIPE" OPTICAL PAPER PATH SENSOR FOR TRANSPARENCIES U.S. C1.355/3SH AND PAPER
John R. Andrews

Proposed Classification

Int. C1. G03g 15/00

REFLECTIVE

ELECTRICAL LEADS

Some copiedprinters use optical interrup sensors to detect the presence or absence of a sheet or transparency. Ordinarily, in the case of a transparency, a white stripe along a side of the transparency is sensed. This stripe is known to be an inconvenience to machine operators. Therefore, a device as shown in the Figure is disclosed which allows detection of transparencies which have no white stripe by the use of a reflective optocoupler type detector. The device consists of a light emitting diode (LED) and a Darlington photo detector (PD) mounted side-by-side in an injection molded package. Operation of the device is shown schematically in the Figure where light emitted from the LED is directed out away from the PD detector and in the absence of any refletive surface in front of the optocoupler gives no signal. As a reflecting surface is moved in front of the optocoupler, light from the LED is reflected into the PD and results in a photocurrent which is converted into a voltage by dropping across a resistor.

Volume 12 Number 1 January/February 1987 39

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A "NO STRIPE" OPTICAL PAPER PATH SENSOR FOR

TRANSPARENCIES AND PAPER (Cont'd)

The standard operation of this device is for use with diffuse reflectors, such as paper, which can reflect about 80% of light incident on it. The new concept that is applied here to allow detection of transparencies with the same device is that the transparency gives a substantial specular reflection. A transparency which has a nominal refraction index of 1.5 rovides two

light...