APPARATUS AND METHOD FOR DETECTING THICKNESS OF PAPER PRODUCT

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority on U.S. Ser. No. 61/173,761, filed Apr. 29, 2009, which is incorporated by reference herein.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

None.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to detecting the sheet quantity of paper products, and more particularly to detecting the sheet quantity of insert material in an insert machine for inserting the insert material into newspapers and other paper products.

2. Description of the Related Art

In paper handling systems, it is often necessary or desirable to detect the sheet quantity of paper products to determine whether the correct number of sheets of paper are being handled or transported.

One particular system in which it is useful to detect the thickness of paper products is in insert machines which insert product such as advertisements, promotional materials, booklets, or other material into host-product, such as magazines or newspapers, particularly Sunday newspapers.

In many cases, the insert product has intrinsic value, such as a promotional or discount coupon. In such a case, it is important that the insert machine insert only one such insert into the host-product. Even in cases where such insert product is not of such intrinsic value, it is important to insert only one of such product to each subscriber, because the quantity of insert product supplied for an insert operation is typically only 1% over the host-product, and it is important that the supply of insert product not be depleted before the host-product is fully-inserted.

Insert machines and other paper-handling systems have used sheet quantity detectors to detect the sheet quantity of the inserts or other paper. The individual inserts may be single sheet or multiple sheets. If more than the desired thickness (or number of inserts) is detected, corrective action usually needs to be taken to remove the excess inserts. Such corrective action is usually done by hand and is time-consuming and costly, and holds up an insert operation which has deadlines in getting the fully-inserted product to its ultimate destination, such as a subscriber's home or newsstand.

Attempts to detect sheet quantity of inserts have included contact sensors, radiation sources and detectors, fiber optic light sensors, Hall sensor devices, and measuring the capacitance of the document. However, those attempts have met varying degrees of success, and some of them are affected by the temperature and humidity of the environment, as well as other process variables.

SUMMARY OF THE INVENTION

The invention provides a system for detecting the sheet quantity of moving sheet product, comprising a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the rollers increases; and a detector to detect the amount of de-concentricity and for providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity.

The invention provides a system for detecting the sheet quantity of moving sheet product, comprising a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the rollers increases; and a detector to detect the amount of de-concentricity of the outer ring component relative to the rotation axis and for providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity, wherein the detection roller comprises a central core and a web material between the central core and outer ring component.

The invention provides a system for detecting the sheet quantity of moving sheet product, comprising a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the detection roller and drive element increases; and a detector to detect the amount of de-concentricity of the outer ring component relative to the rotation axis and for providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity, wherein the detection roller comprises a central core and a web material between the central core and outer ring component, and wherein the detector comprises a detector which detects the position of the outer ring relative to the rotation axis.

The invention provides a system for detecting the sheet quantity of moving sheet product, comprising a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the detection roller and drive element increases; and a detector to detect the amount of de-concentricity and for providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity, wherein the detector comprises a detector which outputs an electrical signal having a component which varies linearly with the amount of de-concentricity.

The invention provides an insert machine having a system for detecting the sheet quantity of moving sheet product, comprising a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the rollers increases; and a detector to detect the amount of de-concentricity and for providing an output corresponding to the thickness of sheet product in dependence on the degree of de-concentricity.

The invention provides a method for detecting the sheet quantity of moving sheet product in a sheet handling machine, comprising providing a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the rollers increases, detecting the amount of de-concentricity, and providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity.

The invention provides a method for detecting the sheet quantity of moving sheet product in an insert machine, comprising providing a detection roller adapted for engagement with a drive element for accepting sheet product between the detection roller and drive element, the detection roller having a rotation axis, and an outer ring component which becomes more de-concentric relative to the rotation axis as the sheet quantity of sheet product between the rollers increases, detecting the amount of de-concentricity, and providing an output corresponding to the sheet quantity of sheet product in dependence on the degree of de-concentricity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a system for detecting the sheet quantity of moving sheet product according to the invention, showing the case where the system is in a no-load condition with the detection roller out of engagement with the high-speed driving disk, with a close-up view of the detection roller;

FIG. 2 is a plan view similar to FIG. 1, but showing a pre-load condition where the detection roller is engaged with the high-speed driving disk and no sheet product there between, with a close-up view of the detection roller;

FIG. 3 is a plan view similar to FIGS. 1 and 2, but showing a load condition of a single sheet product between the detection roller and high-speed driving disk, with a close-up view of the detection roller;

FIG. 4 is a plan view similar to FIGS. 1, 2, and 3, but showing a load condition of two sheets of product between the detection roller and high-speed driving disk, with a close-up view of the detection roller; and

FIG. 5 is a perspective view of the system according to FIGS. 1-4, mounted in an assembly in an insert machine, and with a tire outside the detection roller.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A preferred embodiment of the invention will now be described with reference to use in an insert machine, but the invention is not limited to use in insert machines or the preferred embodiment.

FIG. 1 shows an assembly 10 used to detect the sheet quantity of paper product. The assembly comprises a detection roller 12 (sometimes called roller ring 12 or simply roller 12) and a high-speed driven disk 14. The detection roller 12 comprises a central core 16 having a central rotation axis, an outer metallic ring component 18, and a hub 20 formed of a resilient web material. The assembly also includes a bearing plate 30 on which the detection roller 12 is mounted for rotation, and on which a detector 32 is mounted.

The detector 32 detects the relative position of the roller ring 12, which is metallic, and outputs an electrical signal generally proportional to the distance between the detector 32 and roller 12, even if the roller 12 is rotating and regardless of whether there is paper product between roller 12 and high-speed disk 14. As sheets of paper stock are fed between roller 12 and disk 14, the hub will deform and become de-concentric relative to the central axis of the roller. The amount of deformation and de-concentricity can be detected by the position of the roller ring 18 relative to the detector, even as the roller rotates. The detector output signal will indicate the amount of material (e.g., zero sheets, one sheet, two sheets, etc.) between the roller 12 and disk 14, thereby indicating whether no sheet, one sheet, two sheets, etc., have passed through the roller 12 and disk 14.

FIG. 1 shows the detection roller 12 in a no-load condition, with no deflection or de-concentricity in the roller. In other words, the outer ring component 18 is generally concentric with the central axis of rotation of the roller. The right side of FIG. 1 shows a close-up of the roller in this no-load position.

FIG. 2 shows the detection roller 12 in a pre-load condition, wherein the roller 12 is engaged with the high-speed disk 14, but wherein no sheet material is between the roller 12 and high-speed disk 14. In this condition, as shown in more detail on the close-up in the right of FIG. 2, the roller ring is slightly non-concentric or de-concentric with the central rotation axis. The hub is compressed slightly due to biased engagement of the roller with the high-speed disk 14. The amount of deflection or de-concentricity is about 0.5 mm. The detector signal output correlates this with a pre-load but no-paper or no-insert material condition.

FIG. 3 shows a loaded condition with a single sheet of paper or insert material condition of 3 mm thickness of paper. The amount of deflection is about 3.0 mm, indicating a single insert. There is no motion in the bearing plate 30. The close-up on the right of FIG. 3 shows the roller ring shifted de-concentrically to the left relative to the central rotation axis of the roller 12, due to the compression of the hub on the right side only of the roller 12, from engagement of the roller 12 with the disk 14 and one sheet or insert there-between.

FIG. 4 shows an overloaded or double-loaded condition, where maximum deflection of the roller ring 12 is achieved and bearing plate 30 pivots away from the high-speed disk 14. In this condition, the sensor detects a double-loaded condition of about 6 mm thickness of paper, or two inserts of 3 mm each. In this condition, maximum deflection of the roller ring 12 is achieved (with this design of roller) and bearing plate pivots away from the high-speed disk. In this case, the sensor does not detect additional changes in thickness because the sensor is mounted on the bearing plate 30 which is moving. This condition can be seen in the roller close-up on the right of FIG. 4.

According to the invention, rollers can be arranged to detect more than two sheets of inserts, if desired. In the preferred embodiment in connection with an insert machine, detection of a single insert and double-insert is usually sufficient, as there is very little, if any, possibility of more than two inserts passing through. Even so, the system will detect whether more than one (and thus, two or more) passes through, which indicates excess insert material feeding, whether it is one extra insert or more than one extra insert. In an insert machine operation, the number of extra inserts may not be as important as simply detecting whether there is an excess insert condition.

FIG. 5 shows the assembly of FIGS. 1-4 in part of an insert machine. The roller 12 can be seen having a hub or web with a finned-design with cutouts or less material between the webs, contributing to the resiliency of the hub or web. In FIG. 5, an outer tire is shown surrounding the metallic ring 18.

It has been found that the hardness of a hub or web material of about 65-70 durometer on Shore A scale works well, giving sufficient durability through large numbers of cycles while still providing reliable deflection characteristics.

In insert applications, an acceptable extra insert rate is about 1%, because inserts are normally supplied at a 101% rate of a host material. Above 101%, the insert material would run out before the host material, in addition to a disadvantage of having some customers or subscribers receiving extra promotional material or coupons, which for some promotions is not desired.

Although, in the described embodiment the high-speed disk is not fully-round, it could be fully-round throughout its entire circumference. Also, the detection roller 12 could be a driven roller.

The detector may be an inductive proximity (linear scale) sensor which provides an electrical output generally linearly-related to the amount of deflection (de-concentricity) of the roller ring, and thus, product sheet quantity or thickness.

One way to process the output of the detector is to first process the output signal during a load condition with no sheet material passing there through. A photo detector can be used to confirm that no sheet material is passing there through to get a calibration or baseline reference for an empty or “no paper” condition. The reference signal can be obtained by obtaining a plurality of sample points (e.g., 20) throughout one revolution of the roller and averaged to get a single output value. This process may be repeated a plurality of times (e.g., nine) to get more output values. The values are then averaged, and the average value is taken to be the “empty reference” value, to which a reference of “0” is assigned to indicate zero sheets of paper product.

The next step is to feed single sheets of paper product through the rollers, taking the same samples and values as above. The average value is then taken to be the “product reference” value indicating a single insert. It should be understood that the single insert could be a plurality of sheets which comprise the single insert, comprising a unit sheet quantity, or unit thickness. That average value may be assigned a “product reference” value of 100.

The system is ready to detect sheet quantity. When the detected value is about 100, the product being fed is determined to be a single unit of sheet quantity. When the detected value is about 200, the product being fed is determined to be a double unit of sheet quantity, and so on. A value of about 140-150, is a useful threshold value, below which it is determined to be a single unit of sheet quantity, and above which, a double-sheet quantity, (or more). Higher threshold values for higher numbers of multiple sheets could be 250, 350, etc. Accordingly, any reading between 50 and 150 will be determined to be a single-sheet quantity, and between 150 and 250, a double-sheet quantity, and so on.

A drift compensation can be employed so that the values of 100, 200, 300, etc., and the threshold values of 150, 250, 350, etc., will be adjusted upward or downward, depending on the average values detected within each category of single, double, etc., drift from 100, 200, etc. For example, if after running the machine for awhile, the average value for a single insert is about 102, the threshold values may be adjusted upward by 2% to 153, 255, 357, etc.

When obtaining detector output values, it is desirable to sample the detector output signal during the period of time when sheet product (if there is any) actually would be between the rollers, not taking any samples for the time points when the sheet product enters the rollers or exits the rollers, because at these time points, the rollers jump up at the front edge of the sheet product and jump down at the trailing edge of the street product.

Because the roller may be slightly de-concentric to start, it is advantageous to obtain a plurality of sample points and sample values during a wide, circumferential extent of the roller, to thereby “average out” de-concentricities.

A typical high-speed disk would be about 7 inches in diameter, or about 22 inches in circumference. This disk rotates 360° per revolution. Since a typical roller diameter would be 2.75 inches, or about 8 inches in circumference, the roller would rotate over 3 times per complete revolution of the high speed disk. Since it is expected to have some de-concentricity's in both the roller and high speed disk due to manufacturing tolerances, this could affect the accuracy of the detection system. The sampling of values is controlled to begin at the same point in the cycle (therefore at a specific angle on the high speed disk), it is advantageous to use a sampling window of 1 revolution of the roller so that de-concentricity's will be averaged. For the diameters of the high speed disk and roller mentioned above, this window would be approximately 150°. Handling the sampling window this way allows for less tolerances but still has the ability to be very accurate. Of course, other arrangements can be used. Other detectors, such as a laser, could be used.

Once excess insert material is detected, excess inserts could be removed downstream at the insert operation, if desired. The excess-inserted host material could be tagged and associated with the detector output, so that the excess-inserted host material could be located downstream and corrected by removing the excess insert material.

It should be understood that the present invention has application to different types of machines, and can be located at different locations within a certain type of machine.

One preferred embodiment of the invention is described, but the invention is not limited to this preferred embodiment. The scope of the invention is defined only by way of the following claims.