Sheet-material associating – Associating or disassociating – Signature associating
Reexamination Certificate
1998-11-09
2001-02-20
Skaggs, H. Grant (Department: 3651)
Sheet-material associating
Associating or disassociating
Signature associating
C270S052060, C270S058030, C271S263000
Reexamination Certificate
active
06189879
ABSTRACT:
TECHNICAL FIELD
This invention relates to an apparatus for the measurement of the thickness of flat products such as sheets or signatures and is particularly directed to an apparatus for measuring the thickness of sheets or signatures being fed by a feeding mechanism from a pile of signatures to a transport device such as a pocket feeder, in order to detect a malfunction of the feeding mechanism.
BACKGROUND OF THE INVENTION
In the technology of building books including booklets, magazines, periodicals, and so on, the use of collating systems is well known. These systems typically have a transporting device on which individual signatures are gathered to build a book-block set, which then is finished and bound. Typically a number of hoppers is arranged along the transporting device where each of the hoppers comprises a feeding mechanism for feeding an individual signature from a pile of signatures onto the transporting device, in order to progressively build up the book-block set. Such feeding mechanisms typically employ callipering devices for detecting a malfunction of any of the feeding mechanisms on a given line. Such a malfunction may, for example, result in a delivery of more or less than the intended number of sheets onto the transporting device.
To alleviate these problems, some efforts have previously been made to design collating systems having callipering devices for measuring the thickness of sheets being delivered from a pile of signatures to a transporting device. These calipers typically employ a mechanical feeder gauge which is calibrated to measure the thickness of the sheets being fed from a hopper to a transporting device. Such a thickness measurement device is for example known from U.S. Pat. No. 4,471,954, the disclosure of which is hereby incorporated by reference. This document discloses a transporting device in the form of a pocket feeder having a plurality of sheet loading pockets. Each of the pockets is associated with a sheet ejector for ejecting single sheets into a common sheet conveyor path from the respective pocket. A photo-electric sheet passage detector is mounted between each pocket and the common sheet conveyor path which generates a transparency or reflectivity signal of the sheet and which is compared to a stored averaged signal representative for a single sheet.
Another apparatus for measuring the thickness of sheets being fed from a hopper to a pocket feeder is known from U.S. Pat. No. 5,213,318, the disclosure of which is hereby incorporated by reference. The apparatus of U.S. Pat. No. 5,213,318 comprises a plurality of hoppers for holding signatures where the plurality of pockets is movable past the plurality of hoppers. Each of the pockets has a first fixed roller and a second movable roller being in contact with each other when no sheet is fed between the two rollers. When a flat product passes between the two rollers the second roller is deflected, where the amount of the deflection corresponds to the thickness of the product passing. In order to measure the thickness, the deflection of the second roller is measured. The second roller therefore is mounted on a movable shaft which comprises a plate on one of its ends. The plate is rotatable and arranged within a gap between a light source and a light sensor. Depending on the degree of rotation of the shaft the plate has a corresponding angular position and depending on this angular position it interrupts more or less light from the light source where the amount of interrupted light corresponds to the deflection the rollers.
The accuracy of this method however is limited due to the shadow-effects and due to the limited resolution of the light sensor. Furthermore, every pocket has to be provided with a separate light source.
SUMMARY OF THE INVENTION
It is an object of the present invention to increase the accuracy of the thickness measurement and to provide an improved method of measuring the thickness of flat products.
In summary, according to one aspect of the present invention, an apparatus for measuring the thickness of flat products such as sheets or signatures is disclosed, when the flat products are fed by a feeder from a pile of signatures to a receiving location. The feeder includes a first and a second roller where the first roller is arranged against the second roller to form a nip therebetween for receiving the flat product, wherein the first roller is deflectable when a flat product enters the nip. The apparatus further includes a first reflecting element being arranged on the first roller for reflecting incident light, a light source for directing light to said first reflecting element, a first sensor element for sensing light being reflected from said reflecting element and producing a sensor signal and a calculating unit for calculating the thickness based on that sensor signal.
Solutions according to the present are advantageous, since the present invention can measure the thickness of the flat products with high accuracy. Furthermore, the present invention can magnify the very slight movement of the first roller, which corresponds to the thickness of the flat product. This magnification is achieved without the use of mechanical parts which would cause undesirable vibrations and mass spring settling times.
According to further details of the present invention, the first and second roller and the first reflecting element as well as the first sensor element can be arranged on a movable transporting device, including movable receiving units, so-called compilers, which are a pocket and a pocket feeder. The light source and a calculating unit can be arranged stationary, apart from said movable transporting device. This separation of the components leads to the additional advantage that only one light source is needed.
According to another detail of the present invention, a second reflecting element can be attached to the moving transporting device, for example, to the moving pocket. The first and second roller and the first and second reflecting elements are arranged on the movable transporting device. An additional second sensor element can be provided and both the first and the second sensor elements can be arranged stationary apart from the pocket at a location where they can sense the light reflected from the first and second reflecting elements. When light, reflected from the first reflecting element falls onto the first sensor element a microcomputer begins to count the pulses generated by an encoder. The microcomputer stops counting as soon as light, reflected from the second reflecting element falls onto the second sensor element. As the number of counts refers to the thickness of the flat product the thickness can be calculated from the number of counts.
According to a further aspect of the invention, the apparatus for measuring the thickness of flat products can be used within an apparatus for forming sheet material assemblages, having a plurality of hoppers for holding sheet material, a plurality of receiving units each having a receiving location and feeding means for performing sheet feeding operations to feed sheet material from said hoppers to said receiving locations. The apparatus for forming sheet material can include driving means for sequentially moving each of said receiving units past each of said hoppers in turn and comprises a plurality of first reflecting elements for reflecting incident light, where one of said first reflecting elements is attached to each of said feeding means. One of a plurality of sensor elements is arranged on each of said plurality of receiving units for sensing light reflected from one corresponding reflecting element. A light source for directing light to said first reflecting elements is arranged apart from the receiving units.
According to another aspect of the present invention the apparatus for measuring the thickness of the flat products includes a plurality of hoppers for holding sheet material, a plurality of receiving units each having a receiving location and feeding means for performing sheet feeding operations to f
Conner Charles Jeffrey
Farr Alan Scott
Schlough James Richard
Burns Doane , Swecker, Mathis LLP
Heidelberger Druckmaschinen AG
Mackey Patrick
Skaggs H. Grant
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