Web Sensing Apparatus

Abstract

For use in a xerographic copier/duplicator machine in which paper is fed from a continuous roll and cut to the desired length within the machine, an arrangement for monitoring the movement of the paper and also for providing a visual display of the width of the roll. The paper is caused to continuously move past a sensing station constituting a number of deflectable leaves. A suitable logic circuit coupled to the leaves determines the width of the paper, and provides a warning signal when the paper is exhausted or when it is not being properly fed. The warning signal may be used to halt the operation of the machine so as to prevent jamming or other malfunction of the machine.

Description

BACKGROUND OF THE INVENTION

This invention relates to a web sensing apparatus, and more particularly to an arrangement for providing a signal indicative of the width of an elongated web and a warning signal under certain abnormal operating conditions.

DESCRIPTION OF THE PRIOR ART

In many industrial and commercial applications, a web is fed from a continuous roll over a predetermined path. Stations may be disposed along the path to guide the web and to perform various operations thereon. For example, in a xerographic copier/duplicator machine employing a continuous paper roll, the paper is withdrawn from the roll at a predetermined rate, guided toward a cutting mechanism and cut into sheets of predetermined lengths. The cut sheets are then fed to the xerographic portion of the machine, where a toner pattern corresponding to a desired image is disposed on the sheets and subsequently fused thereto.

In such a copier/duplicator machine, and in many other applications involving the performance of mechanical or chemical processing steps upon a continuous web, it is important that the web be fed over a precisely determined path. For example, lateral misalignment of the paper web employed in a copier/duplicator machine of the aforementioned type will result in undesirable lateral displacement of the image on the paper sheets cut from the web.

In addition, when a copier/duplicator machine of the aforementioned type is employed, which machine is capable of receiving paper rolls of various widths, it is desirable to provide for the machine operator a visual display of the width of the paper roll within the machine at any particular time.

SUMMARY OF THE INVENTION

As herein described, there is provided web sensing apparatus comprising a web supporting plate having a web supporting surface. The web supporting surface is provided with a central aperture and a plurality of laterally spaced pairs of apertures. The apertures of each such pair are disposed on opposite sides of the central aperture.

Disposed in the central aperture is a central web sensing leaf. Disposed in the apertures of each pair are corresponding pairs of web sensing leaves. Each of the aforementioned leaves extends through a corresponding aperture and protrudes outwardly from the web supporting surface. Each leaf is resiliently mounted for inward deflection upon engagement by a web disposed on the web supporting surface.

The lateral distance between the outer pair of leaves most laterally displaced from the central aperture is greater than the width of the widest web to be accommodated by said apparatus.

A plurality of switching elements is also provided, each element being responsive to the position of a corresponding leaf with a respect to the web supporting surface.

A logic circuit is coupled to the switching elements to provide a web width signal indicative of the width of an elongated web longitudinally disposed between the outer leaves. The logic circuit also provides a warning signal when the central leaf is not inwardly deflected, when only one leaf of any pair is inwardly deflected, or when either of the outer leaves is inwardly deflected.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 shows a web sensing apparatus according to a preferred embodiment of the present invention;

FIG. 2 shows one of the sensing leaves and its associated switching element employed in the apparatus of FIG. 1; and

FIG. 3 is a functional block diagram of the control circuitry of the sensing apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, a web supporting plate 10 is provided with a number of rectangular apertures 11 therein. The plate 10, which may preferably comprise a relatively rigid material such as steel or aluminum, is provided with a web supporting surface 12.

An elongated paper web 13 is disposed adjacent to, and preferably in contact with, the web supporting surface 12 of the web supporting plate 10.

The paper web 13 may be maintained adjacent the web supporting surface 12 by suitable web supporting and guiding rollers (not shown) and if desired by a web guide plate (not shown) situated parallel to and spaced slightly apart from the web supporting plate 10, the guide plate being provided with apertures aligned with the apertures 11, and the paper web 13 being fed between the web supporting plate 10 and the web guide plate.

As seen in FIG. 1, the apertures 11 are arranged in pairs on opposite sides of a central aperture 14. The aperture 14 need not be exactly centrally located, but may in fact be offset by a considerable amount without adversely affecting the operation of the apparatus. By the term "central" as herein employed with respect to the aperture 14 and the various components associated therewith, is intended only to indicate a location somewhere between the various pairs of apertures 11.

A deflectable web sensing leaf C extends through the central aperture 14 and protrudes outwardly from the web supporting surface 12 of the web supporting plate 10. Similarly, a pair of web sensing leaves L.sub.1 and R.sub.1 extend through corresponding apertures situated on opposite sides of the central aperture 14, and protrude outwardly from the web supporting surface 12. In the same manner, web sensing leaf pairs L.sub.2, R.sub.2, and L.sub.3, R.sub.3 are provided.

Each of the web sensing leaves is shaped in the form of a relatively thin, rigid sector, and is resiliently mounted so that a slight inward force applied to the leaf will deflect the leaf into the corresponding rectangular aperture. Preferably, the leaves are formed of a suitable rigid material such as steel.

As shown in FIG. 2, a typical one of the leaves such as, e.g., the central leaf C, comprises the end portion of a lever 15 pivotally mounted to a suitable support 16 by means of pivot pin or hinge 17.

Secured to the support 16, or to any other suitable support, is a sensitive switch 18 having an actuating button 19 protruding therefrom. An internal spring (not shown) within the body of the switch 18 resiliently biases the lever 15, and thus the sensing leaf C, in a position such that the sensing leaf protrudes outwardly from the web supporting surface 12 of the web supporting plate 10 through the corresponding aperture 14.

When the web sensing leaf C is inwardly deflected, as by engagement with a paper web disposed on the web supporting surface 12, the leaf is deflected into the aperture 14, thus depressing the actuating button 19 and thereby actuating the sensitive switch 18.

Due to the pivotal mounting of the lever of the sensing leaf, as illustrated in FIG. 2, the leaf may be inwardly deflected merely by frictional contact with the side edge of the web 13 when the web is caused to move across the web supporting surface 12 in a direction as indicated by the arrows 20 in FIG. 1 and 2. Such frictional contact between the side of, e.g., the sensing leaf C and a side edge of the paper web 13, results in generation of a torque about the pivot pin or hinge 17, causing the leaf to rotate about the pivot pin or hinge and depressing the actuating button 19 of the switch 18.

The web 13 is caused to move across the web supporting plate 12 in continuous or intermittent fashion, in a longitudinal direction as indicated by arrow 20, by means of a web drive system 21. If desired, a web skew control system 22, responsive to a suitable signal may be provided to move portions of the paper web 13 laterally so as to maintain the web position along a predetermined path.

The paper web 13 may, for example, be employed as the paper supply for a xerographic copier/duplicator machine, as previously described. In such a machine, paper rolls of varying width corresponding to one desired dimension of a copy may be provided, the paper web 13 being cut to a desired length to establish the other desired dimension by means of a suitable cutting mechanism situated in the machine. For example, a particular copier/duplicator model may be capable of accommodating paper roll widths of 81/2, 11 and 14 inches. For such a group of paper widths, the corresponding distances between the web sensing leaf pairs L.sub.1 /R.sub.1, L.sub.2 /R.sub.2 and L.sub.3 /R.sub.3 may preferably be on the order of 9, 111/2 and 141/2 inches respectively.

The copier/duplicator machine may be provided with a suitable mechanism for laterally centering the paper web 13 with respect to the web supporting plate 12, or alternatively, the web 13 may be manually centered.

When the web 13 centered with respect to the supporting plate 12, and utilizing the sample dimensions recited above, a paper roll having a width of 81/2 inches would depress only the central web sensing leaf C, a web having a width of 11 inches would depress the web sensing leaves L.sub.1, C and R.sub.1, while a web having a 14 inch width would depress the web sensing leaves L.sub.2, L.sub.1, C, R.sub.1 and R.sub.2. Therefore, a different group of web sensing leaves is depressed for each paper roll width accommodated, and a suitable logic circuit connected to the sensitive switches actuated by each of the corresponding leaves may be employed to provide a visual display of the width of the paper web 13. Such a logic circuit arrangement is shown in block diagram form in FIG. 3.

As shown in FIG. 3, a logic circuit 23 is coupled to the sensitive switches 18, 24, 25, 26, 27, 28 and 29 associated with each of the web sensing leaves C, L.sub.1, R.sub.1, L.sub.2, R.sub.2, L.sub.3 and R.sub.3 respectively.

The logic circuit 23 provides a web width signal to the web width visual indicator display 30 on line 31, and a warning signal on line 32. The warning signal is coupled to a "Call Key Operator" visual display 33, which indicated a malfunction within the copier/duplicator machine. The warning signal on line 32 is also coupled to the web drive system 21 or, if desired, the web skew control system 22, to provide automatic response to the detection of a malfunction by the logic circuit 23.

The logical functions provided by the logic circuit 23 for generation of the web width indication signal on line 31 are summarized in Table I, wherein standard Boolean algebraic notation is employed.

TABLE I ______________________________________ C .sup.. L.sub.1 .sup.. R.sub.1 81/2 inch width reading L.sub.1 .sup.. R.sub.1 .sup.. L.sub.2 .sup.. R.sub.2 11 inch width reading L.sub.2 .sup.. R.sub.2 .sup.. L.sub.3 .sup.. R.sub.3 14 inch width reading ______________________________________

Referring back to FIG. 1, it is apparent that regardless of the width of the paper web 13, the central web sensing leaf C should at all times be depressed. Therefore, the failure of the web sensing leaf C to be depressed, as indicated by the electrical output of the corresponding sensitive switch 18, indicates that the web drive system is not functioning properly, in that either (i) the supply of paper has been exhausted, (ii) the web 13 is not being fed across the web supporting surface 12, or (iii) the web 13 is being fed across the web supporting surface 12 in a severely skewed manner.

It is also evident that under proper operation conditions, either both leaves of a particular pair of web sensing leaves L.sub.1 /R.sub.1 or L.sub.2 /R.sub.2 should be depressed, or neither leaf of the pair should be depressed. Any situation in which only one leaf of such a pair is depressed indicates that the paper web 13 is skewed with respect to the desired longitudinal direction of travel, as indicated by the arrow 20, or is laterally displaced from its desired centered position with respect to the web supporting plate 10.

Since the distance between the outermost web sensing leaves L.sub.3, and R.sub.3, is slightly greater than the widest web 13 to be accommodated, the depression of either of these outer leaves indicates that the web 13 is not properly positioned.

The logic circuit 23 determines the presence of the aforementioned malfunction conditions as set forth in Boolean algebraic form in Table II, and provides the aforementioned warning signal on line 32.

TABLE II ______________________________________ C Stop print-"Call Key Operator" Light L.sub.1 .sup.. R.sub.1 + L.sub.1 .sup.. R.sub.1 Stop print-"Call Key Operator" Light L.sub.2 .sup.. R.sub.2 + L.sub.2 .sup.. R.sub.2 Stop print-"Call Key Operator" Light L.sub.3 + R.sub.3 Stop print-"Call Key Operator" Light ______________________________________

In the event that a web skew control system 22 is provided, a suitable skew correction signal may be provided by additional circuitry within the logic circuit 23 to operate the web skew control 22 to cause the web drive system 21 to laterally displace the web 13 toward its desired central position. The particular logic equations required for performance of such a skew correction function are not shown in Table II, but could be readily determined.

Thus, the relatively simple mechanism illustrated in FIG. 1 operates to (i) provide a visual readout of the width of the web 13, (ii) hald operation of the web drive system 21 automatically when mistracking of the paper web 13 occurs, and (iii) prevent operation of the web drive system 21 in the event the paper web 13 has not been properly loaded into the machine of which the apparatus shown in FIG. 1 forms a part.

Claims

I claim:

1. Web sensing apparatus, comprising:

a web supporting plate having a web supporting surface with a central aperture and a plurality of laterally displaced pairs of apertures therein, the apertures of each pair being disposed on opposite sides of said central aperture;

a central web sensing leaf and a plurality of pairs of web sensing leaves, each leaf extending through a corresponding one of said apertures and protruding outwardly from said web supporting surface, each leaf being resiliently mounted for inward deflection upon engagement by a web disposed on said web supporting surface;

the lateral distance between the outer pair of leaves most laterally displaced from said central aperture being greater than the width of the widest web to be accommodated by said apparatus;

a plurality of switching elements, each element being responsive to the position of a corresponding one of said leaves with respect to said web supporting surface; and

a logic circuit coupled to said switching elements for providing a web width signal indicative of the width of an elongated web longitudinally disposed on said plate between said outer leaves, and for providing a warning signal (i) when said central leaf is not inwardly deflected, (ii) when only one leaf of any pair is inwardly deflected, and (iii) when either of said outer leaves is inwardly deflected.

2. Apparatus according to claim 1, further including web drive means for causing an elongated web to progress longitudinally across said web supporting surface, and control means responsive to said warning signal for modifying the operation of said web drive means.

3. Apparatus according to claim 2, wherein said control means responds to said warning signal to cause said web drive means to halt the movement of said web across said web supporting surface.

4. Apparatus according to claim 1, wherein each leaf is pivotally mounted adjacent a corresponding one of said switching elements, so that a corresponding element is actuated by pivotal movement of a leaf upon engagement of said leaf by said web.

5. Apparatus according to claim 1, further including a web width display responsive to said web width signal.