Patent US3827809A successfully refreshed from Google Patents.
US3827809A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuits for deriving a common output signal from a plurality of amplifiers in apparatus for detecting blemishes in sheet material
Assignee: Individual
•
Filing: 1973-05-11
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Granted: 1974-08-06
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Expires: 1993-05-11
Abstract
Abstract A circuit for combining the outputs of several amplifiers, through an array of diodes, so that the combined output has a noise content whose amplitude is less than that of the individual amplifier outputs. The circuit is described as part of an inspection system for detecting blemishes in sheet material flowing past a series of photo-sensitive devices, the amplifiers receiving the outputs of the photo-sensitive devices.
Inventors
- 👤 P Nash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:55
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/01; H03K5/02; G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/89; G01N21/8901; G01N21/8903; G01N21/892; G01N21/896; G01N2201/00; G01N2201/08; G01N2201/0813
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
236 words
Apparatus for detecting blemishes in sheet material arranged to flow past an inspection head of the apparatus, the apparatus comprising light source means arranged to direct light onto the sheet material, a plurality of photosensitive devices arranged in the inspection head in a line transverse to the direction of flow of the sheet material so that the photo-sensitive devices receive light transmitted through or reflected from respective adjacent portions of the sheet material as it passes the photo-sensitive devices, each device being adapted to generate an electrical signal dependent on the intensity of light received by the device, and a circuit for deriving a common output signal from a plurality of amplifiers each adapted to generate in response to an input signal individual to the amplifier an electrical output signal including a random noise signal, the circuit comprising a plurality of rectifiers each having one terminal adapted to be connected to the output terminal of one of the amplifiers and its other terminal connected to a common output terminal, and means for biasing the rectifiers so that, in use, the random noise signals from the amplifiers are combined at the common output terminal to produce a resultant noise signal having an amplitude less than those of the individual noise signals, each of the amplifiers of the circuit being arranged to receive as an input the electrical signal generated by one or more of the photosensitive devices.
Claim 2
Dependent Claim
236 words
Apparatus for detecting blemishes in sheet material arranged to flow past an inspection head of the apparatus, the apparatus comprising light source means arranged to direct light onto the sheet material, a plurality of photosensitive devices arranged in the inspection head in a line transverse to the direction of flow of the sheet material so that the photo-sensitive devices receive light transmitted through or reflected from respective adjacent portions of the sheet material as it passes the photo-sensitive devices, each device being adapted to generate an electrical signal dependent on the intensity of light received by the device, and a circuit for deriving a common output signal from a plurality of amplifiers each adapted to generate in response to an input signal individual to the amplifier an electrical output signal including a random noise signal, the circuit comprising a plurality of rectifiers each having one terminal adapted to be connected to the output terminal of one of the amplifiers and its other terminal connected to a common output terminal, and means for biasing the rectifiers so that, in use, the random noise signals from the amplifiers are combined at the common output terminal to produce a resultant noise signal having an amplitude less than those of the individual noise signals, each of the amplifiers of the circuit being arranged to receive as an input the electrical signal generated by one or more of the photosensitive devices.
Claim 3
Dependent Claim
62 words
Apparatus as claimed in claim 1, in which the inspection head comprises a housing on which are mounted a plurality of the photo-sensitive devices and a separately formed, replaceable collimating member having an aperture through which, in operation, light transmitted through or reflected from the sheet passes, to fall onto the photo-sensitive devices, the collimating member being detachably fixed to the housing.
Claim 4
Dependent Claim
49 words
Apparatus as claimed in claim 2, in which the inspection head comprises a plurality of housings formed by a corresponding number of separate head sections, each head section being detachably mounted on a common support member extending transversely of the direction of flow of sheet material through the apparatus.
Claim 5
Dependent Claim
50 words
Apparatus as claimed in claim 3, in which the support member is hinged to a main frame of the apparatus, to enable the inspection head to be moved from an operative position in which the aperture of each collimating member is close to the path of travel of sheet material.
Claim 6
Dependent Claim
45 words
Apparatus as claimed in claim 2, in which the or each housing is in the form of an airtight case, and means are provided for supplying dust-free air under pressure to the housing, the air leaving the housing through the apertures in the collimating members.
Claim 7
Dependent Claim
32 words
Apparatus as claimed in claim 1, in which adjustment means are provided for adjusting the distance between the apertures of the collimating members and the path of travel of the sheet material.
Claim 8
Dependent Claim
45 words
Apparatus as claimed in claim 1, in which there are provided support means providing a support surface for supporting sheet material as it passes the inspection head, the support means being adjustable to enable the support surface to be made selectively convex, flat or concave.
Claim 9
Dependent Claim
51 words
Apparatus as claimed in claim 2, in which the or each collimating member comprises two side walls converging towards the path of the sheet material, the aperture being defined beTween flat faces formed at adjacent ends of the side walls and parallel to the plane of symmetry of the collimating member.
Claim 10
Dependent Claim
32 words
Apparatus as claimed in claim 8, in which the or each collimating member is divided by ribs extending between the side walls into sections each corresponding to one of the photo-sensitive devices.
Claim 11
Dependent Claim
66 words
Apparatus as claimed in claim 2, in which the or each collimating member comprises two side walls converging towards the path of the sheet material, the adjacent ends of the side walls being cut off in a plane parallel to the plane of movement of the sheet past the members, the aperture being defined by the adjacent edges of the inner surfaces of the side walls.
Claim 12
Dependent Claim
82 words
Apparatus as claimed in claim 2, in which the or each collimating member comprises a slit of adjustable width positioned between the photo-sensitive devices and the path of sheet material, and the light source means comprises lamps positioned at a comparatively large distance from the path of the sheet at the side of the path remote from the photo-sensitive devices, so that substantially parallel beams of light transmitted through sheet material in the path pass through the slit onto the photo-sensitive devices.
Claim 13
Dependent Claim
31 words
Apparatus as claimed in claim 2, in which the or each collimating member includes fibre-optics means arranged to conduct light reflected or transmitted from the sheet material to the photo-sensitive devices.
Claim 14
Dependent Claim
24 words
Apparatus as claimed in claim 12, in which fibre-optics means is provided to conduct light from the light source means to the sheet material.
Claim 15
Dependent Claim
32 words
Apparatus as claimed in claim 1, in which the photo-sensitive devices are adapted to respond to infrared radiation, and infrared filters are disposed between the light source means and the sheet material.
Claim 16
Dependent Claim
59 words
Apparatus as claimed in claim 1, in which the or each collimating member includes an aperture adapted to be oscillated in a direction transverse to the path of sheet material and parallel to the plane of the sheet as it passes the apertures, to detect line defects of the sheet extending in the direction of flow of the sheet.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-05 | 1978-02-04 | 1978-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-05 | 1982-02-04 | 1982-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-05 | 1986-02-04 | 1986-08-06 | $7700.00 | Window Closed / Lapsed |