Fault detector for paper webs

Claim 2

Fault detector apparatus for a web of paper or like material, comprising a light source consisting of a plurality of lightemitting devices and an array of photoelectric devices spaced therefrom and aligned therewith for receiving light emitted thereby, said photoelectric devices responsive to rapid fluctuations in the light transmitted by said web passing between said photoelectric devices and said light source, each said photoelectric device having associated therewith an amplification circuit comprising a diode junction series connected with said photoelectric device between terminal means adapted for connection across a first d.c. potential supply source and an amplification transistor connected between terminal means adapted for connection across a second d.c. potential supply source, said amplification transistor having a control electrode and further having diode junction characteristics substantially the same as those of the first-named said diode junction, and means connecting said control electrode to the junction of said photoelectric device and the first named said diode junction.

Claim 3

Fault detector apparatus for a web of plastic or like material, comprising a light source consisting of a plurality of light-emitting devices and an array of photoelectric devices spaced therefrom and aligned therewith for receiving light emitted thereby, said photoelectric devices responsive to rapid fluctuations in the light transmitted by said web passing between said photoelectric devices and said light source, each said photoelectric device having associated therewith an amplification circuit comprising: a transistor connected across first and second terminal means adapted for connection across a first d.c. potential supply source, said transistor having a control electrode and further having first and second current-passing electrodes connected via connection means to said first and second terminal means respectively; a first load means comprising a diode junction; said load means connected in series with said photoelectric device across third and fourth terminal means adapted for connection across a second d.c. potential supplY source; said photoelectric device connected to said third terminal means and said first load means connected to said fourth terminal means; means connecting said control electrode of said transistor to the junction between said load means and said photoelectric device; output terminal means connected to said first current-passing electrode of said transistor for deriving an output potential therefrom, said transistor having diode junction characteristics substantially the same as those of the first-named said diode jucntion; second load means connected between said first current-passing electrode of said transistor and said first terminal means; third load means connected between said current-passing electrode of said transistor and said second terminal means; and capacitance means interconnecting said second current-passing electrode of said transistor and said fourth terminal means.

Claim 4

Fault detector apparatus for a web of plastic or like material, comprising a light source consisting of a plurality of light-emitting devices and an array of photoelectric devices spaced therefrom and aligned therewith for receiving light emitted thereby, said photoelectric devices responsive to rapid fluctuations in the light transmitted by said web passing between said photoelectric devices and said light source, each said photoelectric device having associated therewith an amplification circuit comprising: a transistor connected across first and second terminal means adapted for connection across a first d.c. potential supply source, said transistor having a control electrode and further having first and second current-passing electrodes connected via connection means to said first and second terminal means respectively; a first load means comprising a diode junction; said load means connected in series with said photoelectric device across third and fourth terminal means adapted for connection across a second d.c. potential supplY source; said photoelectric device connected to said third terminal means and said first load means connected to said fourth terminal means; means connecting said control electrode of said transistor to the junction between said load means and said photoelectric device; output terminal means connected to said first current-passing electrode of said transistor for deriving an output potential therefrom, said transistor having diode junction characteristics substantially the same as those of the first-named said diode jucntion; second load means connected between said first current-passing electrode of said transistor and said first terminal means; third load means connected between said current-passing electrode of said transistor and said second terminal means; and capacitance means interconnecting said second current-passing electrode of said transistor and said fourth terminal means.

Claim 5

The fault detector apparatus of claim 2, wherein said light-emitting devices are infra-red lamps.

Claim 6

The fault detector apparatus of claim 2, wherein said photoelectric devices are arranged in a substantially linear array.

Claim 7

The fault detector apparatus of claim 4, wherein said photoelectric devices are grouped in units, the sensitivity of said apparatus being proportional to the number and spacing between said devices in each said unit and the length of each said unit in the direction of said array.

Claim 8

The fault detector apparatus of claim 5, wherein each said unit includes a circuit board having mounted thereon the amplification circuits for the photoelectric devices in the said unit associated therewith, said circuit board of each said unit being of substantially the same configuration and construction as corresponding circuit boards of the remaining said units.

Claim 9

The fault detector apparatus of claim 2, wherein said photoelectric devices are grouped into symmetrical elongated units, said photoelectric devices in each unit forming a substantially linear array and said units arranged end-to-end, each said unit containing a circuit board for said amplification circuits and each said circuit board being of similar configuration and construction to the remaining said circuit boards, the resolution of said apparatus in the direction of said array being proportional to the spacing of the photoelectric devices and the length of each said unit in the direction of said array.

Claim 10

The fault detector apparatus of claim 2, wherein said photoelectric devices are grouped in a series of units, the totality of said photoelectric devices forming a substantially straight line, each said unit having a slitted member positioned with the slit thereof in the path of light rays from said light source and incident upon said photoelectric devices.

Claim 11

The fault detector apparatus of claim 8, wherein the slitted members of said units define in combination, a continuous slit, extending over substantially the entire length of said array.

Claim 12

The fault detector apparatus of claim 2, wherein said photoelectric devices are grouped into a plurality of elongated units, said photoelectric devices in each said unit forming a substantially linear array, and stop means provided in the path of light from said light source and incident upon said photoelectric devices for defining the area of web material monitored by the devices in said unit.

Claim 13

The fault detector apparatus of claim 2, further comprising a signal processing station and means connecting the amplification output circuits of said devices to input means of said station.

Claim 14

The fault detector apparatus of claim 5, further comprising a signal processing station and means interconnecting the amplification output circuits of the individual devices in each said unit to give a common output for each unit, and means connecting said common outputs to individual input means of said signal processing station.

Claim 15

The fault detector apparatus of claim 2, wherein said photoelectric devices are phototransistors.