NOTCH-FINDING MECHANISM AND METHOD OF USING THE SAME

Abstract

One embodiment of the invention is a notch finding mechanism that at least partially supports and drives a core carrying printer media. The notch finding mechanism includes a notch finding spring and a plurality of support posts that extend from a support disk. The notch finding spring includes a plurality of fingers constructed of a flexible sheet material, and the fingers are positioned circumferentially and adjacent each other to define a plurality of spaces between the fingers. In addition, the fingers are biased radially outwardly, and each of the fingers has a free end that has a width that is approximately matched to a width of a notch in an end of the core. The bias of one of the fingers urges the free end of the finger into the notch aligned with the finger when the core is placed over the fingers and is rotated a small amount.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No. 60/719,411, filed Sep. 21, 2005, which is hereby incorporated herein in its entirety by reference.

FIELD OF INVENTION

The present invention involves a notch finding mechanism for coupling a drive assembly to a hollow cylindrical core and, more particularly, the use of a notch finding mechanism to couple a printer media roll to a drive assembly.

BACKGROUND OF THE INVENTION

Hollow cylindrical cores are used in the printing industry to carry rolls of printer media, such as paper, labels, or ink ribbon. The cores can be driven to rotate in a forward or backward direction by coupling a drive assembly to the core. One method of coupling a drive assembly to a core includes engaging keys on a drive disk into notches in the end of the core. More specifically, in the example shown in FIG. 1, the drive disk 10 extends in a radially outward direction from the drive shaft 12, and extending past the periphery of the drive disk 10 in a radially outward direction are the one or more keys 14, or protrusions. In the example shown in FIGS. 2A and 2B, the hollow cylindrical core 20 includes one or more notches 22 at an end 23 of the core 20 that extend from an inner diameter 24 of the core 20 towards an outer diameter 25 of the core 20. To load the core 20 onto the keyed disk 10 described above, an operator rotates the core 20 until the notches 22 at the end 23 of the core 20 align with the keys 14. The keys 14 are then engaged into the notches 22 in the core 20, allowing the transfer of rotation of the shaft 12 to the core 20.

This loading operation can be cumbersome for the operator, especially when the core 20 is carrying a large printer media roll. In addition, the core 20 can slip away from the disk 10, causing the keys 14 to disengage from the notches 22 and the media to misfeed and jam the printer.

Therefore, a need in the art exists for a device that radially couples a core onto a drive shaft to transmit the rotational energy from the drive shaft to the core.

BRIEF SUMMARY OF THE INVENTION

According to various embodiments, a notch finding mechanism is provided for at least partially supporting and driving a core of a printer media supply. The core defines at least one notch at an end of the core, and the notch finding mechanism includes a drive shaft and a notch finding spring. The notch finding spring is driven by the drive shaft and includes a plurality of fingers positioned circumferentially about a central axis and adjacent to each other. Each finger is biased in a radially outward direction and has a free end. The bias of the fingers urges the free end of one of the fingers into the notch defined in the end of the core when the core is placed over the plurality of fingers and rotated.

In another embodiment, a notch finding spring is provided for at least partially supporting and driving a core of a printer media supply. The core defines at least one notch at an end of the core, and the notch finding spring includes a plurality of fingers. The fingers are positioned circumferentially about a central axis and adjacent each other, are biased in a radially outward direction, and each have a free end. The bias of the fingers urges the free end of one of the fingers into the notch defined in the end of the core when the core is placed over the plurality of fingers and rotated.

According to another embodiment, a method of supporting and driving a core of a printer media supply is provided. The method includes the steps of: (1) positioning the core over a notch finding spring that has a plurality of fingers with a radially outward bias, and (2) rotating the core and the notch finding spring relative to each other a small amount until one of the fingers biases into a notch defined in the core.

In yet another embodiment, a notch finding spring is provided for driving a core that defines at least one notch adjacent to an end of the core. The notch finding spring includes a plurality of fingers that are positioned circumferentially about a central axis and adjacent to each other, are biased in a radial direction, and have a free end. The free end includes an engaging portion, and the bias of the fingers urges the engaging portion of one of the fingers into the notch when the core is placed adjacent to the plurality of fingers and rotated.

In another embodiment, a notch finding spring is provided for driving a core. The notch finding spring is secured to the core and includes a plurality of fingers that are positioned circumferentially about a central axis and adjacent to each other. In addition, each finger is biased in a radial direction and includes a free end, and the free end includes an engaging portion that, because of the bias of each finger, is urged into a notch defined adjacent to an end of a drive shaft when the drive shaft is placed adjacent to the plurality of fingers and relatively rotated a small amount.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is an end view of a prior art coupling mechanism;

FIG. 2A is a side view of a hollow cylindrical core having a notched end;

FIG. 2B is an end view of the notched end of the hollow cylindrical core of FIG. 2A;

FIG. 3 is a plan view of a printer and a notch finding mechanism according to one embodiment of the invention;

FIG. 4A is a perspective view of a notch finding mechanism and clutch assembly according to one embodiment of the invention;

FIG. 4B is a side view of the notch finding mechanism and clutch assembly of FIG. 4A;

FIG. 5 is an exploded view of the notch finding mechanism and clutch assembly of FIG. 4A;

FIG. 6 is a perspective view of the notch finding mechanism and clutch assembly of FIG. 4A coupled to a hollow cylindrical core;

FIG. 7 is a side view of a finger of the notch finding spring of FIG. 4A;

FIG. 8 is a perspective view of a core mounted onto the notch finding mechanism of FIG. 4A;

FIG. 9 is a top view of the notch finding spring of FIG. 4A;

FIG. 10 is an exemplary dimensional specification for the notch finding spring of FIG. 4A;

FIG. 11 is a partial plan view of a cut detail for the notch finding spring of FIG. 10;

FIG. 12 is a cross sectional view of an exemplary dimensional specification for a finger of the notch finding spring of FIG. 4A;

FIG. 13 is a cross sectional view of the notch finding mechanism and clutch assembly of FIG. 4A;

FIG. 14 is a perspective view of a notch finding spring according to another embodiment of the invention;

FIG. 15 is a perspective view of the notch finding spring of FIG. 14 coupled with a hollow cylindrical core;

FIG. 16A is a plan view of an exemplary cut detail for the notch finding spring of FIG. 14;

FIG. 16B is a partial plan view of the cut detail of FIG. 16A;

FIG. 17A is a side view of a notch finding spring according to another embodiment of the present invention;

FIG. 17B is a plan view of the notch finding spring of FIG. 17A;

FIG. 18 is a side view of notch finding spring according to one embodiment of the invention;

FIG. 19 is a side view of a notch finding spring according to one embodiment of the invention;

FIG. 20 is a side view of a notch finding spring according to one embodiment of the invention;

FIG. 21 is a side view of a notch finding spring according to one embodiment of the invention;

FIG. 22 is a side view of a notch finding spring according to one embodiment of the invention;

FIG. 23 is a side view of a notch finding spring according to one embodiment of the invention;

FIG. 24 is a perspective view of a notch finding spring according to one embodiment of the invention; FIG. 25 is a side view of a finger of a notch finding spring according to one embodiment of the invention;

FIG. 26 is a side view of a finger of a notch finding spring according to one embodiment of the invention;

FIG. 27 is a side view of a finger of a notch finding spring according to one embodiment of the invention;

FIG. 28 is a side view of a finger of a notch finding spring according to one embodiment of the invention; and

FIG. 29 is a side view of a notch finding spring according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention address one or more of the above needs and achieve other advantages by providing a notch finding mechanism for radially coupling the rotation of a drive shaft to a hollow cylindrical core. For example, certain embodiments of the notch finding mechanism include a notch finding spring mounted to an end of the drive shaft and having a plurality of fingers that are radially outwardly biased so as to seat within a notch defined in the media supply core with a relatively small amount of rotation between the spring and the core. This is enabled by the large number of fingers, such as twelve fingers, that are circumferentially positioned and configured to insert as a group into the core. And, in various embodiments, the outward bias of the fingers allows them to automatically seat in the notch or notches of the core, enabling single-handed loading of the core without attention or regard to the relative rotational position between the drive shaft and the core.

In one embodiment, the present invention includes a notch finding spring for at least partially supporting and driving a core of a printer media supply. The core defines at least one notch at its end. Included in the notch finding spring are a plurality of fingers that are circumferentially positioned adjacent to each other. Further, the fingers are biased in a radially outward direction, and each of the fingers includes a free end that can move radially at least a small amount. The bias of at least one of the fingers urges its free end into the notch defined in the end of the core when the core is placed over the plurality of fingers and relatively rotated (i.e., the core is rotated, the spring is rotated, or both) a small amount, such as 45°, 30° or less.

In addition, each of the fingers is constructed of a flexible sheet material. For example, the sheet material fingers may extend from a fixed end in a first axial direction, allowing their insertion into the core. Each of the fingers may also have an arcuate shaped profile that is defined by the fingers extending in a first direction from the fixed end, bending in a radially outward direction through an arc portion and extending in a second axial direction generally opposite the first axial direction toward the free end.

In another aspect, each of the fingers has a width matched approximately to that of the notch for a firm fit. Also, a first diameter of around the free ends of the fingers is greater than an inside diameter of the supply core, and a second diameter around the arc portion is less than the inside diameter of the supply core. This allows easy placement of the second diameter into the core and urging of the free ends at the first diameter into the notch.

Each of the fingers may have a varying width, being tapered at the free end for insertion into the notch, thicker at a middle portion and tapered near the arc portion. The taper near the arc portion promotes the insertion of several rigid support posts supported by the drive shaft between the fingers. These support posts provide torsional stability for the spring and radial support for reasonable centering of the rotational axis of the core independently of the flexing of the spring fingers.

Various embodiments of the present invention provide several advantages. For example, the notch finding spring maybe easily manufactured by punching and drawing from a flexible sheet material, such as stainless steel or beryllium copper. As another example, the notch finding spring can be used with existing clutch and drive assemblies by sizing the width of the fingers to approximately match the width of the notches in existing cores. Further, the bias of the fingers and spacing of the fingers close together allows for single-handed loading of the core onto the notch finding spring without regard to relative rotational position. In addition, movement of the core in the axial direction is prevented or restricted as a result of the bias of the fingers in a radially outward direction against the inner diameter of the core.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

Printer and Drive Assembly

As shown in FIG. 3, the printer 30 includes a rectangular housing 31. The housing 31 includes a base 33 and a lid or cover (not shown). The base 33 has a rectangular shape with a wall structure that extends upwardly from the base 33 to support and contain various electronic and mechanical assemblies of the printer 30.

The base 33 of the housing 31 supports a print head assembly 40, a drive assembly 50, and a clutch assembly 60. The print head assembly 40 includes a platen roller 41, a print head 42, and media guide surfaces 43. The print head assembly 40 urges a printer media 80 between the platen roller 41 and the print head 42 to allow the print head 42 to print on the printer media 80.

The drive assembly 50 includes a drive motor 51 that rotates a drive shaft 52. The drive motor can include, for example, a stepper motor. The drive shaft 52 has a driven end 53 adjacent to the drive motor 51 and a free end 54 opposite the driven end 53. The drive shaft 52 further includes a drive disk 55 that extends in a radially outward direction from the axis of rotation of the drive shaft 52 and is positioned on the drive shaft 52 near the free end 54. The drive assembly 50 further includes a support pin 56 that is positioned opposite the drive shaft 52. A non-driven end of the hollow cylindrical core is rotatably mounted on and vertically supported by the support pin 56, which may or may not be keyed.

The clutch assembly 60 engages to transmit the rotational energy from the drive shaft 52 and disengages when the torque on the drive shaft 52 at the clutch assembly 60 exceeds a particular amount. As shown in FIGS. 4A and 4B, the clutch assembly 60 includes the drive disk 55, a support disk 61, and a first, second, and third intermediate frictional disks 201, 202, 203, which are shown in FIG. 5. The drive disk 55 is integrally attached to the drive shaft 52 and extends in a radially outward direction from the drive shaft 52. The support disk 61 is separate from the drive shaft 52 and includes a central aperture 63 for receiving the end 54 of the drive shaft 52 and a mounting surface 64 for mounting adjacent to the drive disk 55. Between the support disk 61 and the drive disk 55 are the intermediate frictional disks 201, 202, 203 that have frictional material on both sides and frictionally engage each other to couple the support disk 61 to the drive disk 55 with a designed “torque versus rotational” slip behavior.

The first intermediate frictional disk 201 is coupled to the drive disk 55, and the second intermediate frictional disk 202 is coupled to the support disk 61. The third intermediate frictional disk 203 is positioned between the first 201 and second intermediate frictional disks 202 and frictionally engages the first 201 and second intermediate frictional disks 202. In one embodiment, the intermediate frictional disks 201, 202 are made of cartridge brass, the support disk 61 is made of an unfilled polycarbonate, and the drive disk 55 and drive shaft 52 are made of injection molded nylon 6/6.

To couple the intermediate frictional disks 201, 202 to the drive disk 55 and the support disk 61, the drive disk 55 and the support disk 61 include one or more keys 210 that protrude axially from the mating surfaces of each disk 55, 61 and extend lengthwise in a radially outward direction from the center of each disk 55, 61, as shown in FIG. 5. The keys are positioned towards the center of the drive disk 55 and the support disk 61. Each of the intermediate frictional disks 201, 202 include a central aperture 215 which is adapted for receiving the end of the drive shaft 52, and one or more notches 216 that extend in a radially outward direction from the central aperture 215. The notches 216 receive the keys 210 on the support disk 61 and drive disk 55, which couples the drive disk 55 to the first intermediate frictional disk 201 and the support disk 61 to the second intermediate frictional disk 202. The keys 210 and notches 216 are not limited to being positioned in the center of the disks 201, 202, 55, and 61 and could be positioned, for example, along the periphery of the disks 201, 202, 55, and 61.

When the torque on the drive shaft 52 at the clutch assembly 60 is below a particular amount, intermediate frictional disks 201, 202 engage the third intermediate frictional disk 203, and the rotational energy of the drive shaft 52 is transferred to the support disk 61. If the torque on the drive shaft 52 at the clutch assembly 60 exceeds the particular amount, the intermediate frictional disks 201, 202 disengage from the third intermediate frictional disk 203, allowing the drive disk 55 to rotate independently of the support disk 61.

The printer described above is for illustration purposes only. It is envisioned that one of skill in the art would understand that the present invention is suitable for use in a variety of types of printers, such as thermal head printers, portable printers, or thermal transfer printers, or even other driven media or core driven devices, such as film rolls or paper rolls.

Notch Finding Mechanism

A notch finding mechanism 100 of one embodiment of the present invention couples a hollow cylindrical core carrying printer media to the drive assembly of a printer. FIGS. 5 and 6 show the notch finding mechanism 100 according to one embodiment that includes a notch finding spring 101 and the support disk 61 having a plurality of support posts 230. The notch finding spring 101 includes a plurality of arcuate-shaped fingers 102 formed of a flexible sheet material and a base portion 104.

Advantageously, the large number of fingers 102 enables a relatively small rotation (e.g., 45°, 30° or less) between the notch finding spring 101 and the core of the media supply. For example, the amount of rotation will generally be the same or less than 360° divided by the number of fingers, such as 6, 8 or the illustrated twelve fingers 102.

The fingers 102 have a fixed end 110 and a free end 108, and the fixed ends 110 of the fingers 102 are integrally attached to and positioned circumferentially around the base portion 104 and adjacent to each other, as shown in FIG. 6. A plurality of spaces 106 are defined between the fingers 102, and the spaces 106 allow the free end 108 of each finger 102 to move in a radial direction independently of adjacent fingers 102. Furthermore, the free end 108 of each finger 102 has a reduced width w_f compared to the portion of the finger 102 adjacent to the free end 108. The width w_f of the free end 108 is approximately matched to the width w_n of a notch 22 on the end 23 of a cylindrical core 20, such as the core 20 shown in FIGS. 2A and 2B, allowing the free end 108 of a finger 102 to seat within the notch 22.

FIG. 7 illustrates the arcuate-profile of one of the fingers 102. Each finger 102 extends from its fixed end 110 in a first axial direction and then bends in a radially outward direction through an arc portion 112 and extends towards the free end 108 in a second axial direction, which is substantially opposite the first axial direction. The portion of the finger 102 between the arc portion 112 and the free end 108 is biased in a radially outward direction r from an axis of rotation R of the notch finding spring 101.

As shown in FIGS. 6 and 9, each arc portion 112 has a reduced width compared to the portions of the finger 102 adjacent to the arc portion 112. The reduced width defines a circular shaped space 120 between adjacent fingers 102 that can receive a support post 230. Retaining the increased width along the remaining portions of the finger 102 provides strength for the finger 102 and more surface area with which to frictionally engage the inner diameter 24 of the core 20.

In addition, the diameter of the notch finding spring 101 around the arc portion 112 of the fingers 102 is less than the inner diameter 24 of the core 20, and the diameter of the notch finding spring 101 around the free ends 108 of the fingers 102 is greater than the inner diameter 24 of the core 20. Because the diameter around the arc portion 112 is less than the inner diameter 24 of the core 20, placement of the core 20 over the notch finding spring 101 is facilitated. And, because the diameter of the notch finding spring 101 around the free ends 108 of the fingers 102 is greater than the inner diameter 24 of the core 20, the free ends 108 of the fingers 102 are urged against the inner diameter 24 of the core 20 or into notches 22 that align with the fingers 102. An illustration of the notch finding spring 101 positioned within the notched end 23 of the cylindrical core 20 is shown in FIG. 8.

The base portion 104 defines an annular collar 114 that extends in a radially outward direction r from the axis of rotation R of the notch finding spring 101 to the fixed end 110 of the fingers 102, as shown in FIGS. 6, 7, and 9. The annular collar 114 includes an inner diameter that approximately matches the outer diameter of the drive shaft 52, or a mounting shaft extending axially from the end of the drive shaft 52, allowing the annular collar 114 to be placed over the end of the drive shaft 52 or mounting shaft. Alternatively, the base portion 104 can be solid (not shown) or define an aperture through the center of the base portion 104, as shown in FIG. 17B, for receiving a fastener, such as, for example, a screw or bolt, to secure the base portion 104 adjacent to the end 54 of the drive shaft 52.

One method of manufacturing a notch finding spring 101 includes cutting into a flexible sheet of material, such as beryllium copper or full-hard 301 stainless steel. The annular collar 114 is cut into the sheet of material, and the fingers 102 are defined by cutting slots into the material that extend from the outer diameter of the annular collar 114 to the edge of the sheet of material. The slots are positioned adjacent to each other and circumferentially around the outer diameter of the annular collar 114. After the slots are cut, the portion of each finger 102 between the fixed end 110 and the arc portion 112 is bent in a first axial direction relative to the axis of rotation R of the notch finding spring 101, the arc portion 112 of each finger 102 is bent in a radially outward direction, and the portion between the arc portion 112 and the free end 110 is bent in a second axial direction that is substantially opposite the first axial direction. When the notch finding spring 101 is finished, the slots correspond to the spaces 106 defined between the fingers 102.

To bend the fingers 102 into the arcuate-shaped profile, a mandrel, a first hollow cylinder, and a second hollow cylinder can be utilized. At least a portion of the mandrel has an outer diameter that is substantially the same as the inner diameter of the annular collar 114, and the cut form of the notch finding spring 101 is mounted onto the mandrel by engaging the mandrel into the annular collar 114. The first hollow cylinder has an inner diameter that is approximately the same as the desired outer diameter of the notch finding spring 101 as measured around the portions of each finger 102 intermediate the fixed end 110 and the arc portion 112. And, the second hollow cylinder has an inner diameter approximately the same as the desired outer diameter of the notch finding spring 101 around the free ends 101. The mandrel is maneuvered to engage a portion of the cut form into the first hollow cylinder, bending the fixed ends 110 of the fingers 102 in the first axial direction. Then, the portions of each finger 102 between the free end 108 and the arc portion 112 are engaged into the second hollow cylinder, which bends the fingers 102 radially outward and downward in the second axial direction.

FIGS. 10 through 12 illustrate exemplary dimensional specifications for manufacturing the notch finding spring 101 from a sheet of a beryllium copper alloy having a yield strength of about 150,000 psi and a thickness Q of 0.005 inches. For example, as shown in FIG. 10, the inner diameter A of the annular collar 114 is approximately 0.185 inches and the distance B between the center of the annular collar 114 to the fixed end 110 of each finger 102 is approximately 0.135 inches. To define the twelve fingers 102 shown in FIG. 10, twelve slots corresponding to the twelve spaces 106 are cut into the material. In addition, the inner radius G of the transition from the fixed end 110 to the portion of the finger 102 intermediate the fixed end 110 and the arc portion 112 is about 0.050 inches, the diameter H of the notch finding spring 101 around the free ends 108 of the fingers 102 is about 0.558 inches, the diameter J of the notch finding spring 101 around the arc portions 112 is approximately 0.465 inches, the diameter W of the notch finding spring 101 around the fixed ends 110 is 0.214 inches, and the radius K of the portion of the slot that is adjacent the annular collar 114 is about 0.007 inches. The specifications further show the portion of the finger 102 extending from the arc portion 112 to the free end 108 as having a curvature having an angle L of about 190° and a radius P of about 0.4 inches, and the arc portion 112 has an angle M of about 25° and a radius N of about 0.025 inches. In addition, the length Y of the finger 102 from the arc portion 112 to the free end 108 is about 0.251 inches, and the length X that the free end 108 extends below a plane of the annular collar 114 is 0.046 inches.

According to FIG. 11, the angle C from the center of one of the fingers 102 to the edge of the finger is about 12°, the angle D from the center of one finger 102 to the center of an adjacent finger 102 is about 42°, and the angle E of each space between the fingers 102 is about 6°. In addition, the diameter F of the space 106 between two adjacent arc portions 112 is about 0.055 inches.

FIG. 12 shows another exemplary dimensional specification for manufacturing the arcuate-shaped fingers 102. For example, the inner diameter A of the annular collar 114 is about 0.125 inches, the radius G of the transition from the fixed end 110 to the portion of the finger 102 intermediate the fixed end 110 and the arc portion 112 is about 0.010 inches, the outer radius V of the transition from the fixed end 110 to the portion of the finger 102 intermediate the fixed end 110 and the arc portion 112 is about 0.020 inches, and the arc portion 112 has an angle M of about 25° and a radius N of about 0.025 inches. In addition, the specifications show the portion of the finger 102 extending from the arc portion 112 to the free end 108 as having a curvature having an angle L of about 170° and a radius P of about 0.4 inches. Furthermore, the flexible sheet material out of which the finger 102 is cut is shown as having a thickness Q of approximately 0.010 inches. The dimensions described above in relation to FIGS. 10 through 12 are exemplary and are one of skill in the art would understand that variations are within the scope of the invention.

The notch finding spring 101 is not limited to the specific embodiment described above in relation to FIGS. 4A through 12. For example, in one alternative embodiment, which is shown in FIGS. 14 through 16B, the fingers 102 do not have a reduced width at the free end 108 or a reduced width at the arc portion 112. Instead, the width of the fingers 102 gradually tapers from the free end 108 towards the arc portion 112, and the free end 108 has a width that is approximately matched with the width of a notch 22 in the core 20. In addition, the spaces 106 between the fingers 102 have a width approximately the same as the diameter of one of the support posts 230 that extend from the support disk 61. The exemplary cut detail of a notch finding spring 101 according to this embodiment is shown in FIGS. 16A and 16B. For example, the angle of each space 106 between the fingers 102 is about 6°, and the distance from the center of the annular collar 114 to the fixed end 110 outeach finger 102 is about 0.1 inches. In another embodiment, which is not shown, the width of each finger 102 is uniform along the length of the finger 102.

In addition, another embodiment of the notch finding spring 101, which is shown in FIGS. 17A and 17B, includes non arcuate-shaped fingers 102. Instead, the fingers 102 extend outwardly and downwardly from the base portion 104 without bending through an arc portion 112.

As mentioned above, the notch finding mechanism 100 further includes a support disk 61. According to the embodiment shown in FIGS. 4A through 6, the support disk 61 includes a plurality of support posts 230 that extend in an axial direction from the outer surface 221 of the support disk 61. The support posts 230 are positioned circumferentially around the central aperture of the support disk 61. When the annular collar 114 of the notch finding spring 101 is positioned over the drive shaft 52 and adjacent the support disk 61, each of the spaces 106 between the fingers 102 aligns with and receives one of the support posts 230. By extending through the each of the spaces 106 between the fingers 102, the support posts 230 prevent the fingers 102 from excessive torsional deflection. In another embodiment in which a clutch assembly 60 is not used, the support posts 230 extend axially from the drive disk 55.

In the embodiment shown in FIG. 13, the support disk 61 includes an annular groove 220 on the outer surface 221 of the support disk 61, which is the surface opposite the mounting surface 64. The annular groove 220 is adapted for seating the free ends 108 of the fingers 102 of the notch finding spring 101. By seating the free ends 108 in the annular groove 220, the free ends 108 are prevented from being forced in a radially inward direction past the inner diameter of the annular groove 220, thereby protecting the fingers 102 from excessive radial deflection.

Assembly of Notch Finding Mechanism to Drive Assembly The rotational energy of the drive motor 51 is transferred to the core 20 by securing the notch finding spring 101 to the support disk 61 and placing the core 20 over the notch finding spring 101. To secure the notch finding spring 101 adjacent to the support disk 61 and to hold the support disk 61 in frictional contact with the drive disk 55, one embodiment of the notch finding mechanism 100 further includes a compression spring 250, a washer 255, and a threaded bolt 256. As shown in FIGS. 5 and 13, the support disk 61 and the intermediate frictional disks 201, 202, 203 are placed over the end 54 of the drive shaft 52 and stacked adjacent the drive disk 55, as described above in relation to FIG. 5. Then, the annular collar 114 of the notch finding spring 101 is placed over the end 54 of the drive shaft 52 and seated adjacent the support disk 61.

Next, a helical compression spring 250 is placed over the end 54 of the drive shaft 55 and seated adjacent the annular collar 114 of the notch finding spring 101. A washer 255 is then placed intermediate the helical compression spring 250 and a head portion of a threaded bolt 256, and a threaded portion of the threaded bolt 256 is engaged through the center of the compression spring 250 and into a threaded aperture 260 that extends axially from the end 54 of the drive shaft 52 or mounting shaft towards the driven end 53 of the drive shaft 52. When the bolt 256 is fully engaged in the threaded aperture 260, the bolt 256 urges the washer 255 towards the helical compression spring 250, which forces the compression spring 250 to push the annular collar 114 of the notch finding spring 101 into frictional engagement with the support disk 61 and the support disk 61 into frictional engagement with the drive disk 55 via the intermediate disks 201, 202, 203. FIG. 13 illustrates a cross-sectional view of the notch finding spring 101 described above in relation to FIG. 4A engaged into the notched end of the core 20 and coupled to the drive assembly 50 via the clutch assembly 60 described above in relation to FIG. 5.

When the core 20 is placed over the notch finding spring 101, a finger 102 may or may not be aligned with a notch 22. If a finger 102 is aligned with a notch 22, the bias of the finger 102 causes it to seat into the notch 22 automatically. If a finger 102 is not aligned with a notch 22, the drive assembly 50 rotates the notch finding spring 101 until a finger 102 aligns with the notch 22. Because a finger 102 automatically seats within a notch 22 when the finger 102 is aligned with the notch 22, the operator does not have to adjust the core 20 once the core 20 is placed over the notch finding spring 101.

In another embodiment, which is not shown, the notch finding spring 101 is coupled to the drive shaft 52 without a clutch assembly 60. Support posts 230 extend axially from the drive disk 55 and are positioned circumferentially around the axis of rotation of the drive shaft 52. The annular collar 114 of the notch finding spring 101 is placed over the end 53 of the drive shaft 52 and positioned to seat adjacent to the surface of the drive disk 55 such that the spaces 106 between the fingers 102 are aligned with and receive the support posts 230. The use of a compression spring 250, washer 255, and threaded bolt 256, such as described above in relation to FIG. 13, can be utilized to secure the notch finding spring 101 into frictional contact with the drive disk 55.

Another embodiment of the invention is a radially biased spring for axially coupling a drive shaft to a hollow cylindrical shaft. The radially biased spring includes a base portion and a plurality of fingers. Each of the fingers includes a fixed end and a free end, and the fixed end of each finger is integrally attached to the base portion. The fingers are positioned circumferentially around the base portion so as to define a plurality of spaces between the fingers. The base portion of the radially biased spring is securely mounted to the end of the drive shaft so that the fixed ends of the fingers are adjacent the end of the drive shaft and the free ends are positioned adjacent the body of the drive shaft. When a hollow cylindrical shaft is placed over the fingers, the fingers are biased in a radial outward direction against the inside diameter of the cylindrical shaft to couple the drive shaft to the cylindrical shaft.

In an alternative embodiment, shown in FIG. 18, a radially biased spring includes a base portion 104 and a plurality of fingers 302 that extend in an axial direction from the base portion 104 away from the end of the drive shaft 52 towards a cylindrical shaft 320. The fingers 302 are biased in a radially outward direction, and each finger 302 includes a protrusion 303 that extends in a radially outward direction from the finger 302. The cylindrical shaft 320 includes a driven end 321, and notches 322 are positioned along an inner diameter of the cylindrical shaft 320 adjacent to the driven end 321. The notches 322 are positioned such that they will align with the protrusions 303 on the fingers 302 when the fingers 302 are engaged into the cylindrical shaft 320. The radially outward bias of the fingers 302 urges the protrusions 303 on the fingers 302 into engagement with the notches 322 in the cylindrical shaft 320, coupling the cylindrical shaft 320 to the drive shaft 52.

The protrusions 303 in the embodiment shown in FIG. 18 are rectangular shaped. However, the protrusions 303 can take on alternative shapes, such as spherical, triangular, or trapezoidal, depending on the shape of the notches 322 in the cylindrical shaft 320. For example, in FIG. 19, the protrusions 303 are circular shaped and the notches 322 are dimple shaped. This embodiment advantageously provides a self-clutching assembly by allowing the protrusions 303 to disengage the dimple shaped notches 322 when the torque at the end of the drive shaft 52 exceeds a predetermined amount.

In another embodiment, shown in FIG. 20, the protrusions 303 on the fingers 302 extend in a radially inward direction and the fingers 302 are biased in a radially inward direction. In addition, the cylindrical shaft 320 includes notches 322 positioned along its outer diameter adjacent to the driven end 321 of the cylindrical shaft 320. To couple the drive shaft 52 to the driven end 321 of the cylindrical shaft 320, the fingers 302 are engaged into the driven end 321 of the cylindrical shaft 320, and the bias of the fingers 302 urges the protrusions 303 on the fingers 302 into engagement with the notches 322 on the outer diameter of the cylindrical shaft 320.

In yet another embodiment, shown in FIG. 21, the fingers 302 are biased in a radially inward direction, and each finger 302 includes two arcs that define an S-shape. A first arc 304 is positioned adjacent to the free end of the finger 302 and is convex relative to the axis of rotation of the drive shaft 52, and a second arc 305 is positioned adjacent to the first arc 304 and is concave relative to the axis of rotation of the drive shaft 52. The cylindrical shaft 320 includes a toroidal shaped collar 325 extending in a radially outward direction from the outer diameter of the cylindrical shaft 320 adjacent to the driven end 321 of the cylindrical shaft 320. The collar 325 has a diameter that is greater than the outer diameter of the cylindrical shaft 320 and slightly less than the inner diameter defined by the second arcs 305 of the fingers 302. The cylindrical shaft 320 further includes a plurality of notches 322 positioned along the outer diameter of the cylindrical shaft 320 between the toroidal collar 325 and the non-driven end of the cylindrical shaft 320. To couple the drive shaft 52 to the driven end 321 of the cylindrical shaft 320, the fingers 302 are engaged over the driven end 321 of the cylindrical shaft 320 and the bias of the fingers 302 urges the second arcs 305 of the fingers 302 into engagement with the toroidal collar 325 and the first arcs 304 into engagement with the notches 322 on the outer diameter of the cylindrical shaft 320. The engagement of the second arcs 305 with the toroidal collar 325 prevents axial movement of the cylindrical shaft 320 relative to the drive shaft 52, and the rotational energy from the drive shaft 52 is transferred to the cylindrical shaft 320 through the engagement of the first arcs 304 into the notches 322 adjacent to the toroidal collar 325.

FIG. 22 shows a variation of the embodiment described in relation in FIG. 21 wherein the cylindrical shaft 320 has a toroidal collar 325 that extends from the outer diameter of the cylindrical shaft 320 in a radially outward direction, and the notches 322 are positioned along a crest 326 of the toroidal collar 325 on the inner diameter of the cylindrical shaft 320. The fingers 302 include at least one arc 306 that is concave relative to the axis of rotation of the drive shaft 52, and upon engaging the fingers 302 into the cylindrical shaft 320, the arcs 306 on the fingers 302 engage into the toroidal collar 325 and the notches 322 therein. The engagement of the arcs 306 with the toroidal collar 325 prevents axial movement of the cylindrical shaft 320 relative to the drive shaft 52, and the rotational energy from the drive shaft 52 is transferred to the cylindrical shaft 320 through the engagement of the arcs 306 into the notches 322 on the toroidal collar 325.

In yet another alternative embodiment, fingers 302 extend axially from the circumference of a cylinder 310 having a threaded exterior portion 311, as shown in FIG. 23. The threaded exterior portion 311 engages a threaded inner diameter 340 of a drive shaft 52. The fingers 302 include protrusions 303 that extend in a radially inward direction, and these protrusions 303 engage notches 322 positioned within a trough of an annular collar 330 that extends in a radially inward direction from the outer diameter of the cylindrical shaft 320 when the fingers 302 are engaged over the cylindrical shaft 320. If the torque on the drive shaft 52 exceeds a particular amount at the end of the drive shaft 52, the protrusions 303 on the fingers 302 disengage from the notches 322 or the threaded portion 311 of the cylinder 310 disengages from the threaded inner diameter 340 of the drive shaft 52.

FIG. 24 illustrates another embodiment in which the end of the drive shaft 52 includes a first face 345 that includes a plurality of protrusions 341 extending from the first face 345 in an axial direction away from the drive shaft 52. The cylindrical shaft 320 includes a driven end 321 that has a second face 350, and the second face 350 of the driven end 321 includes a plurality of notches 352 that align with the protrusions 341 on the drive shaft 52 and are configured for receiving the protrusions 341 when the driven end 321 of the cylindrical shaft 320 and the end of the drive shaft 52 are place adjacent to each other. When the protrusions 341 of the drive shaft 52 are engaged into the notches 352 on the cylindrical shaft 320, the rotational energy of the drive shaft 52 can be transferred to the cylindrical shaft 320. In addition, a plurality of fingers 302 extend from the end of the drive shaft 52 in an axial direction towards a cylindrical shaft 320. To prevent the axial movement of the cylindrical shaft 320 relative to the drive shaft 52, the fingers 302 further include a protrusion 303 that extends in a radially inward direction, and the protrusion 303 engages a groove 330 in the outer diameter of the cylindrical shaft 320.

FIGS. 25 through 28 illustrate exemplary alternative embodiments of finger shapes. For example, FIGS. 25 and 26 illustrate fingers 302 that have a free end 108, a fixed end 110, and an elongated body extending between the free end 108 and the fixed end 110. A protrusion 303 extends from the elongated body between the fixed end 110 of the finger 302 and a middle portion of the elongated body. The protrusion 303 may extend in a radially inward direction as shown in FIG. 25 or in a radially outward direction as shown in FIG. 26.

FIG. 27 illustrates another embodiment of a finger 302 that has a free end 108, a fixed end 110, and an elongated body extending between the free end 108 and the fixed end 110. A protrusion 303 extends from a middle portion of the elongated body, and the free end 108 of the finger 302 defines a hook shape. The hook-shaped free end 108 can bend radially inward or radially outward to facilitate the insertion of the finger 302 into the inner diameter of the cylindrical shaft or onto the outer diameter of the cylindrical shaft, respectively.

FIG. 28 illustrates a finger 302 having a fixed end 110, a free end 108, and a U-shaped body that extends between the free end 108 and the fixed end 110 and includes an arcuate portion 401. The finger 302 extends from a base portion 104 in a first axial direction, bends in a radially outward direction through the arc portion 401, and extends in a second axial direction to the free end 108, wherein the first axial direction is substantially opposite the second axial direction. In addition, the finger 302 includes a protrusion 303 that extends in a radially outward direction and is positioned between the arc portion 401 and the free end 108 of the finger 302. The finger 302 is suited for engaging notches located along the inner diameter of a cylindrical shaft. In an alternative embodiment, which is not shown, the finger extends from the base portion in the first axial direction, but bends in a radially inward direction through the arc portion before extending in the second axial direction to the free end. The finger also includes a protrusion positioned between the arc portion and the free end of the finger, but unlike the finger shown in FIG. 28, the protrusion extends in a radially inward direction. This finger is adapted for engaging notches located along the outer diameter of the cylindrical shaft.

In other alternative embodiments, the fingers 302 described above are positioned on the driven end 321 of the cylindrical shaft 320, and the structure for engaging the fingers 302 is positioned on the drive end of the drive shaft 52. For example, as shown in FIG. 29, fingers 302 extend from the driven end 321 of the cylindrical shaft 320 towards the drive shaft 52. The drive shaft 52 includes a hollow cylindrical portion at the drive end that includes a plurality of notches 441. The fingers 302, which are biased in a radially outward direction, engage the notches 441 and transfer rotational energy from the drive shaft 52 to the cylindrical shaft 320.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended concepts. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A notch finding mechanism for at least partially supporting and driving a core of a printer media supply, said core defining at least one notch at an end of the core, the notch finding mechanism comprising:

a drive shaft; and

a notch finding spring driven by the drive shaft, said notch finding spring comprising: a plurality of fingers positioned circumferentially about a central axis and adjacent to each other; each of said fingers being biased in a radially outward direction; each of said fingers having a free end;

wherein the bias of one of the fingers urges the free end of said finger into the notch defined in the end of the core when the core is placed over the plurality of fingers and rotated.

2. A notch finding mechanism of claim 1, wherein each of the plurality of fingers is constructed of a flexible sheet material.

3. A notch finding mechanism of claim 2, wherein the fingers define a plurality of spaces therebetween.

4. A notch finding mechanism of claim 3, wherein said free end of each of the fingers has a width approximately matched to a width of the notch defined at the end of the supply core.

5. A notch finding mechanism of claim 4, further comprising a support disk supporting the plurality of fingers.

6. A notch finding mechanism of claim 5, further comprising a plurality of support posts extending in the axial direction from a surface of the support disk, each of said plurality of support posts extending into a respective one of said plurality of spaces defined between said fingers.

7. A notch finding mechanism of claim 6, further comprising a frictional clutch positioned between the support disk and a drive disk connected to the drive shaft.

8. A method of supporting and driving a core of a printer media supply, the method comprising:

positioning the core over a notch finding spring having a plurality of fingers with a radially outward bias; and

rotating the core and the notch finding spring relative to each other a small amount until one of the fingers biases into a notch defined in the core.

9. A method of claim 8, wherein the small amount is 30° or less.

10. A notch finding spring for driving a core, said core defining at least one notch adjacent to an end of the core, the notch finding spring comprising:

a plurality of fingers;

said fingers positioned circumferentially about a central axis and adjacent to each other;

each of said fingers being biased in a radial direction;

each of said fingers having a free end, said free end comprising an engaging portion;

wherein the bias of one of the fingers urges the engaging portion into the notch when the core is placed adjacent to the plurality of fingers and rotated.

11. A notch finding spring of claim 10 wherein the fingers are biased in a radially inward direction.

12. A notch finding spring of claim 10 wherein the engaging portion is at an end of the free end of each finger.

13. A notch finding spring of claim 10 wherein the engaging portion is adjacent an end of the free end of each finger.

14. A notch finding spring of claim 10 wherein the engaging portion is a protrusion extending in a radial direction from each finger, said protrusion adapted for engaging the notch in the core.

15. A notch finding spring of claim 10 wherein the engaging portion comprises a first arcuate shape having a first diameter and the notch comprises a second arcuate shape having a second diameter, the first diameter being slightly smaller than the second diameter, and wherein the engaging portion is adapted to disengage the notch when a torque at the engaging portion exceeds a predetermined amount.

16. A notch finding spring of claim 10 wherein the fingers are biased in a radially outward direction.

17. A notch finding spring of claim 16, wherein each of the plurality of fingers is constructed of a flexible sheet material.

18. A notch finding spring of claim 17, wherein each of the plurality of fingers extends from a fixed end in a first axial direction.

19. A notch finding spring of claim 18, wherein each of said fingers has an arcuate-shaped profile, said arcuate-shaped profile defined by each of said fingers extending in the first direction from the fixed end and bending in a radially outward direction through an arc portion to extend in a second axial direction generally opposite the first axial direction and toward said free end.

20. A notch finding spring of claim 19, wherein the fingers define a plurality of spaces therebetween.

21. A notch finding spring of claim 20, wherein said free end of each of the fingers has a width approximately matched to a width of the notch defined at the end of the supply core.

22. A notch finding spring of claim 21, wherein a first diameter around the free ends of the plurality of fingers is greater than an inside diameter of the supply core and a second diameter around the arc portions of the plurality of fingers is less than the inside diameter of the supply core.

23. A notch finding spring of claim 22, wherein each of said fingers includes a middle portion between said arc portion and said free end, said middle portion having a width greater than a width of said free end.

24. A notch finding spring of claim 23, wherein said arc portion of each of said fingers has a reduced cross section.

25. A notch finding spring of claim 24, wherein said plurality of spaces at locations between the arc portions are adapted for aligning with and receiving a plurality of rigid support posts.

26. A notch finding spring for driving a core, said notch finding spring being secured to the core, the notch finding spring comprising:

a plurality of fingers;

said fingers positioned circumferentially about a central axis and adjacent to each other;

each of said fingers being biased in a radial direction;

each of said fingers having a free end, said free end comprising an engaging portion;

wherein the bias of one of the fingers urges the engaging portion into a notch defined adjacent to an end of a drive shaft when the drive shaft is placed adjacent to the plurality of fingers and relatively rotated a small amount.