2. Description of Related Art Binder strips utilizing heat activated adhesives are commonly used to bind a stack of sheets using a desk top binding machine. A typical binder strip is disclosed in detail in U. S. P. No. 4,496,617, the contents of which are fully incorporated herein by reference. Referring to the drawings, Figure 1 shows an exemplary binder strip 10, with the adhesive side exposed. The strip includes an elongated substrate (not designated), typically made of paper. A central band 14 of heat activated adhesive is disposed along the length of the substrate. When activated by heat, band 14 becomes molten and has a low viscosity so as to wet the edges of the pages to be bound. A pair of outer adhesive bands 12A and 12B are provided which are made of a heat activated adhesive which is high tack and high viscosity. The outer bands function to secure the strip to the front and back cover sheets of the bound stack.

The actual binding of a stack is usually carried out by a desk top binding machine such as described in U. S. P. No. 5,052,873, the contents of which are fully incorporated herein by reference. Figure 2 is a simplified diagram of an exemplary binding machine 18. The binding machine supports the stack 20 of sheets to be bound. An operator inserts a single strip 10 into an opening 21 located in the side of the machine. A sensor detects the presence of the strip 10, causing a drive motor to be activated, which causes the strip to be drawn into the machine by of a pair of pinch rollers. Once the

strip is loaded into the machine, the strip is applied to the stack 20 using both pressure and heat so as to bind the stack.

Originally, the typical binding machine 18 operated with basically one type of elongated binder strip 10, with there being narrow, medium and wide strips to accommodate thin, medium and thick stacks of sheets, respectively, to be bound. A typical binding machine includes apparatus for automatically measuring the stack 20 of sheets to be bound and then indicating to an operator, by way of a display 24, the width of binder strip to be inserted into the machine. The machine is provided with various apparatus for either preventing an operator from inserting a binder strip of incorrect width into the machine or for detecting the width of the strip and then ejecting a strip if the width is incorrect.

More recently, various new types of binder strips have been developed, or are in the process of being developed, which incorporate different binding techniques. The binding machines are ideally configurable to operate differently depending upon the type of strip being used. By way of example, some strips inherently require less time to heat the heat activated adhesive than other strip types. In those cases where less time is required, the machine could complete a binding sequence more quickly as compared to other strip types. The machine must have the information as to the type of strip being used so that the binding sequence can be appropriately modified.

For other types of strips, the end of the strip first inserted into the machine is critical. If the wrong end is inserted first, a proper bind cannot be carried out.

One approach would be for the operator to communicate this information to the machine by some form of manual data entry such as a keyboard 22 (Figure 2) or the like. However, one very important objective of most desktop binding systems is to permit anyone having a minimal amount of training to operate the binding machine. If an operator is required inspect a binder strip and to then manually input the necessary information into the

machine, the operator must be well trained. In any event, it is preferable to minimize the need for such manual input since even a trained operator can make an error that may result in damaging the stack of sheets to be bound.

This problem will become more acute when numerous new types of strips are developed.

In addition, binder strips sometimes include gaps in the adhesive near both ends of the strip. As shown in Figure 1, the outer adhesive bands 12A and 12B extend to both ends of the strip, but the central adhesive band 14 does not. Thus, gaps 16A and 16B are formed in the adhesive. These gaps function to receive excess molten adhesive 14 during the binding sequence.

If the gap at the distal end of the strip, the end first inserted into the machine, is not present, the excess adhesive 14 at that end will have a tendency to flow away from the strip and on to components of the binding machine.

Since both ends of the strip 10 are provided with such gaps, the operator normally need not be concerned as to which end is first inserted into the machine. However, in some instances, an operator will cut a strip to accommodate a stack having a non-standard length. By way of example, a strip that is 11 inches long could be cut to 8 1/2 inches so that the top edge of an 8 1/2 by 11 inch stack can be bound rather than the normal 11 inch edge. In that event, the cut edge of the strip will not have a gap. This is not a problem if an operator knows or remembers to insert the cut strip with the end having a gap into the machine first. However, if the operator inserts the cut end first, the machine could be contaminated with adhesive.

The present invention overcomes the above-noted shortcoming of prior art strips by providing an efficient manner of encoding strips with information, typically relating to the strip type and strip direction of travel during insertion, which can be sensed by the binding machine without intervention by the operator. The binding sequence can then be automatically optimized for the strip type. The encoding also preferably indicates which strip end was

inserted first so, if incorrect, the machine can sense the error, eject the strip and display an error message instructing the operator to properly reinsert the strip. These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following Detailed Description of the Invention together with the drawings.

SUMMARY OF THE INVENTION An encoded binder strip which controls operation of a binding machine.

The binder strip includes an elongated substrate and an adhesive matrix disposed on a surface of the substrate. A predetermined encoded pattern is formed on the surface of the matrix, with the pattern including relatively low and relatively high reflectivity regions. The encoded pattern can be sensed when the machine is loaded into the binding machine so that the machine operation is optimized for the particluar type of binder strip.

BREIF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of a conventional binder strip, with the adhesive side showing.

Figure 2 is a simplified elevational view of a conventional desk top binding machine.

Figure 3 shows a portion of a binder strip in accordance with the present invention having an encoded surface.

Figures 4A, 4B and 4C are flow charts, illustrating the operation of a binding machine configured to read an encoded binder strip in accordance with the present invention.

Figure 5 is a simplified diagram of a sensor arrangement installed in a binding machine for reading an encoded binder strip.

Figure 6 is a block diagram of the binding machine apparatus for sensing the encoded strip, decoding the information and for controlling the action of the binding machine in response to decoded information.

Figure 7 is an alternative binder strip in accordance with the present invention with the encoded information being disposed only along one side of the strip to permit the feed direction of the strip to be ascertained.

Figure 8 is a schematic diagram of machinery for the manufacture of encoded binder strips, including a chill roller and an encoding roller.

Figure 9 is a side view showing an outer surface of the encoding roller of Figure 8.

DETAILED DESRIPTION OF THE INVENTION Referring again to the drawings, Figure 3 depicts part of the adhesive surface of an encoded binder strip 30 in accordance with the present invention. The encoding is preferably accomplished by varying the reflective characteristics of the adhesive surface of the binder strips. The light and dark bands on the adhesive strip of Figure 3 represent high and low reflectivity areas, respectively. The normal surface of the adhesive has a fairly high reflectivity. It has been found that selectively abrading the surface of the adhesive is one technique for reducing the reflectivity. Another technique is to pass the adhesive over a rough surface soon after the molten adhesive has been applied to the substrate during the manufacture of the binder strip, as will be explained in greater detail. In both cases, the adhesive surface is textured to reduce the reflectivity.

Figure 5 is a simplified schematic diagram of a portion of a modified strip loading mechanism of a binding machine. As previously noted in connection with Figure 2, an operator inserts one end of a binder strip into the machine. An outer optical sensor, which includes a light source 34A such as a LED and a light detector 34B such as a photodiode, senses that a strip has been inserted into the machine. A drive motor (not depicted) is then automatically activated which drives a drive roller 32. The strip 30 is drawn into the machine between the drive roller 32 and a pinch roller 28. A reflectivity sensor including a transmitter section 36A and receiver section 36B is disposed above the strip feed path so that the encoding on the strip can be read as the strip is loaded into the machine. The drive motor is a stepper motor so that the number of steps that the motor is driven corresponds to a given location on the strip. The number of steps can be stored in a memory for later reference.

As can be seen in Figure 6, the output of the reflectivity sensor is forwarded to a decoder 38. The decoded information typically relates to that

type of binder strip that was just loaded into the machine. That information is sent to the binding machine control circuitry as represented by block 40.

This information may, for example, modify the amount of time that an adhesive is heated or may simply cause the machine to eject the loaded tape and to display an error message such as"Strip Inserted Incorrectly-Reverse Strip and Reinsert".

In one embodiment, the strip type is determined by comparing that portion of the strip that has a relatively high reflectivity to that portion that has a relatively low reflectivity. A unique pattern is formed on the strip and is repeated several times to reduce the likelihood of errors. By way of example, Figure 3 shows an encoded surface of a portion of a binder strip 30, with dimension L2A, L2B, etc representing the common length of the repeating pattern. Thus, the region between points PA and PC encompasses one complete cycle of the pattern, with the region between points PC and PE encompass a second complete cycle of the same pattern. This common cycle length may be, for example, one inch for all strip types and includes a relatively low reflectivity portion represented by the dark sections of the drawing (the region between points PA and PB, for example) and a relatively high reflectivity portion represented by the light sections of the drawing (the region between points PB and PC, for example). The length L1A, LIB, etc. of the low reflectivity portion, corresponds to the binder strip type. To reduce error, the ratio of LI to L2 is actually used to identify the strip type. Thus, for example, ratios of 1/8,2/8,3/8,4/8,5/8,6/8 and 7/8 may represent seven different strip types.

Figures 4A, 4B and 4C represent an exemplary decoding sequence used to read an encoded strip. One goal of the decoding sequence is to eliminate potential errors due to damaged or otherwise defective encoding on a binder strip. Thus, a substantial amount of redundancy is employed in the encoded strip itself and in the decoding sequence. Referring to Figure 4A, the sequence begins as indicated by element 42. At this point, an operator has

placed a stack 20 of sheets in binding machine 18 as shown in Figure 2. In most cases, the binding machine will then sense the thickness of the stack 20 and will indicate by way of display 24 the width of binder strip to be inserted into the machine (wide, medium or narrow). As indicated by block 44, the display will then instruct the operator to insert a strip 10 of appropriate width into opening 21 of the binding machine. The drive motor (not shown) will then be turned on and will proceed to cause the strip to be drawn into the machine. As indicated by element 46, the outer optical sensor (transmitter 34A and receiver 34B of Figure 5) determines whether a strip 10 is disposed within the sensor. At this point, if a strip is not sensed, it usually means the operator has, for some reason, withdrawn the strip from the machine. This will cause the drive motor to stop, as represented by block 48. If a strip 10 is sensed, the strip is driven into the machine, with the strip passing under the reflectivity sensor 36A/36B. The location of the strip with respect to sensor 36A/36B is always known since the number of step motor steps is counted and recorded.

A determination is first made as to whether the operator has inserted a cut edge of the strip into the machine. As previously noted, if the strip is cut to accommodate a non-standard length stack, the operator should insert the uncut edge first so that a gap 16A/16B (Figure 1) will be positioned properly so as to absorb any excess molten adhesive 14. Each end of the binder strip has a relatively high reflectivity segment having a length LS. Length LS is selected to be longer than any of the relatively high reflectivity segments on the strip so that if the strip is cut at any location, the worst case length of any leading relatively high reflectivity segment will be less than a minimum value Lsmin. Thus, as indicated by element 50, the drive motor is driven one step and a determination is made, as shown by element 52, if point PA is detected by sensor 36A/36B. Sensor 36A/36B senses the transition from a relatively high reflectivity region to a relatively low reflectivity region. Initially, the transition will not be detected so, as indicated by element 52, the sequence

will return to element 46 and the motor will be stepped a second time as indicated by element 50, with this loop continuing until point PA is detected.

If the location of what appears to be point PA exceeds a predetermined maximum value it is possible that the strip has been encoded only along one edge so that the encoding cannot be detected, as will be explained. In that case, the operator incorrectly inserted the strip in reverse.

As previously noted, some strip types must be inserted in the proper direction to ensure that the portion of the strip intended to be associated with the front cover of the stack 20 will, in fact, be applied to the front cover of the stack. As shown be element 56, the sequence jumps to element 82 of Figure 4C which indicates that the drive motor is reversed so that the strip will proceed to be ejected. An error message will also be displayed, indicating by way of example, that the strip should be reversed and reinserted.

Eventually, the outer sensor 34A/34B (Figure 5) will indicate that the strip has been ejected so that the sequence can return to the beginning at element 42 of Figure 4A where the machine waits to sense the reinserted strip.

Assuming that point PA has been detected, a value that corresponds to LS, the distance between the leading edge of the strip 30 and point PA, is stored. Assuming that the location of point PA does not exceed some maximum distance (element 56 of Figure 4A), a determination is then made as to whether the stored value for LS is less than a stored value minimum valued Lsmin, as indicated by element 58. If the value is less, the relatively high reflectivity region at the end of the strip must be all or part of an intermediate relatively high reflectivity region that was cut by the operator.

In that event, the strip was improperly inserted with the cut end first so that the strip needs to be reversed and reinserted. Thus, the sequence will proceed to element 82 of the Figure 4C flow chart where the strip is ejected and an error message displayed.

Assuming that the strip has been properly inserted, the strip will continue to be driven into the machine so that the next two points, points PB

and PC, can be ascertained, as indicated by element 60. Point PB is detected when the strip encoding changes from a relatively low reflectivity region to a relatively high reflectivity region. The distance between points PA and PB represents length L1A (Figure 3). Point PC is detected when the strip encoding changes from a relatively high reflectivity to a relatively low reflectivity. The distance between points PA and PC represents length L2A.

The measured value of L2A should correspond to one cycle L2 of the embedded coding, a value which is fixed for all strip types. If L2A exceeds a maximum value for L2, maximum value Lmax2, points PB and PC were not found. In that event, the strip will be ejected, as indicated by element 62, according to the flow chart of Figure 4C.

Assuming that the maximum value Lmax2 was not exceeded, a determination is then made as to whether the measured value L2A falls within a predetermined acceptable range for the nominal value for cycle length L2.

As indicated by element 64, if L2A falls outside the acceptable range, the values corresponding to points PA and PB are not used to determine the strip type. The sequence then returns to element 60 and an attempt is made to read the next two points (PC and PD) on the strip as the strip is fed into the binding machine.

If the value of L2A is within the acceptable range, the ratio of values L1A to L2A can then be used to determine the strip type. However, in order to further reduce possible errors, a second measurement is taken while the strip continues to be drawn into the binding machine. The sequence will proceed to element 66 of Figure 4B. As indicated, the location of the next two points on the strip, points PD and PE, is then determined. The distance between points PC and PE corresponds to a second measurement L2B of cycle length L2. If the measured value L2B exceeds the maximum value Lmax2, points PD and PE were not found. In that event, the strip will be ejected according to the flow chart of Figure 4C, as indicated by element 68.

Assuming that L2B has not exceeded the maximum value, a determination is

made as to whether the measured value of L2B falls within the acceptable range for the nominal value of cycle length L2, as indicated by element 70. If the value of L2B does not fall within the range, a further measurement is attempted as indicated by element 70 of Figure 4B and element 60 of Figure 4A. If the value of L2B is acceptable, the two ratios of L1A/L2A and LlB/L2B are then calculated, as indicated by element 72. Next, the two ratios are compared with one another as indicated by element 74. If the two ratios differ from one another more than a predetermined amount, at least one of the measurements was in error. As indicated by element 74 and 60, a further pair of measurements is made.

Assuming that the ratios agree within the acceptable tolerance, the ratios are used in connection with a look up table stored in the binding machine 18, as indicated by element 76. The look up table produces one of seven selected strip type identifiers based upon an input that corresponds to a measured range of L1/L2 ratios. The comparison indicated by element 74 confirms that the two measurements fall within one of the ranges, so that a selected one of the seven strip type identifiers will be produced from the look up table. The binding machine then displays the strip type and proceeds to automatically adjust the operation of the binding sequence to correspond to the strip type as shown by element 78.

As previously noted, one technique for determining if a binder strip has been correctly inserted into the binding machine is to encode the strip only along one edge of the strip as shown in Figure 7. The optical sensor 36A/36B (Figure 5) is offset from the binder strip feed path so that the encoded information 84 on binder strip 30 can be detected only when the strip is fed into the binder machine in one direction. If the strip is fed in the opposite direction, the encoded information cannot be read, the machine ejects the strip and causes an error message to be displayed instructing the operator to reinsert the strip in the proper direction as previously described in connection with element 56 of Figure 4A and Figure 4C. As is the case with the encoded

pattern of Figure 7, the encoded pattern is preferably arranged asymmetrically on the adhesive surface with respect to the central longitudinal axis of the strip.

Figure 8 shows one exemplary technique for encoding the subject binder strips. The binder strips are typically manufactured in a continuous process. Adhesives strips 12A/12B and 14 (Figure 1) are deposited on a single web 86 of substrate material by way of adhesive extruder 84 which ejects molten heat activated adhesive stripes as the substrate material passes under the extruder. Typically, the web 86 is sufficiently wide to allow several binder strips to be made in parallel. Extruder 84 deposits adhesive stripes for six or more binder strips so that multiple binder strips are formed at the same time. The extruders for the central adhesive band 14 are periodically turned off and on so that the gaps 16A and 16B are formed at what will be the ends of the strip.

After the heated adhesive is deposited on the substrate 86, the substrate is passes over a chill roller 88 that cools the adhesive sufficiently so as to prevent the adhesive from flowing off of the substrate. The substrate web 86 and adhesive are passed over an encoding roller 90 having a patterned outer surface (Figure 9) that corresponds to the encoded information to be imbedded onto the strips. The pattern is formed on the outer roller surface by etching or other suitable means so as to produce a roughened surface in preselected regions. When the adhesive is passed over the outer surface of roller 90, a textured surface is selectively formed on the surface of the adhesive since the adhesive is still soft at this point. The textured surface has a reflectivity that is low relative to the reflectivity of the non-textured surface. Idler roller 92 maintains tension on the substrate to assist in the formation of the textured surfaces. The substrate 86 is then passed through a cutter (not shown) that operates to cut the substrate into individual binder strips.

Thus, a novel encoded binder strip and related method have been disclosed. Although one embodiment has been described in some detail, it is to be understood that certain changes can be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims. By way of example, other coding schemes than disclosed herein could be readily adapted which can be used to distinguish binder strip types and binder strip feed directions. Further, other techniques can be employed for altering the reflectivity of the adhesive other than the use of a textured wheel. An advantage of the use of a roughened wheel surface is that very little modification of the binder strip manufacturing process is required so that the encoding process adds essentially nothing to the cost of manufacturing the strip. Typically, encoding roller 90 does not even need to be added to the manufacturing equipment since the roller is usually present, functioning as a chill roller.