Method for fabricating a flexible belt with a puzzle-cut seam

FIELD OF THE INVENTION

This invention relates in general to a low profile seam preparation method and, more specifically, to a thin seam preparation method as well as a post seaming treatment process for flexible imaging member belts application.

BACKGROUND OF THE INVENTION

Flexible imaging member belts in electrostatographic imaging system are well known in the art. Typical flexible imaging member belt include, for example, electrophotographic imaging member belts or photoreceptors for electrophotographic imaging systems, ionographic imaging member belts or electroreceptors for electrographic imaging systems, and intermediate image transfer belts for transferring toner images used in an electrophotographic or an electrographic imaging system. These belts are usually formed by cutting a rectangular sheet from a web containing at least one layer of thermoplastic polymeric material, overlapping opposite ends of the sheet, and joining the overlapped ends together to form a welded seam. The seam extends from one edge of the belt to the opposite edge. Generally, these belts comprise at least a supporting substrate layer and at least one imaging layer comprising thermoplastic polymeric matrix material. The “imaging layer” as employed herein is defined as the charge transport layer of an electrophotographic imaging member belt, the dielectric imaging layer of an ionographic imaging member belt, and the transfer layer of an intermediate transfer belt. Thus, the thermoplastic polymeric matrix material in the imaging layer is located in the upper portion of a cross section of an electrostatographic imaging member belt whereas the substrate layer being in the lower portion of the cross section of the electrostatographic imaging member belt. Although the flexible electrostatographic imaging member belts of interest include the mentioned types, for simplicity reasons, the discussion hereinafter will be focused on the electrophotographic imaging member belts as the representation.

Flexible electrophotographic imaging member belts are usually multilayered photoreceptors that comprise a substrate, an electrically conductive layer, an optional hole blocking layer, an adhesive layer, a charge generating layer, and a charge transport layer and, in some embodiments, an anti-curl backing layer. One type of multilayered photoreceptor comprises a layer of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. A typical layered photoreceptor having separate charge generating (photogenerating) and charge transport layers is described in U.S. Pat. No. 4,265,990, the disclosure of the foregoing patent being hereby incorporated by reference verbatim, with the same effect as though such disclosure were fully and completely set forth herein. The charge generating layer is capable of photogenerating holes and injecting the photogenerated holes into the charge transport layer.

Although excellent toner images may be obtained with multilayered belt photoreceptors, it has been found that as more advanced, higher speed electrophotographic copiers, duplicators and printers were developed, fatigue induced cracking at the welded seam area is frequently encountered during photoreceptor belt cycling. Moreover, the onset of seam cracking has also been found to rapidly lead to seam delamination due to fatigue thereby shortening belt service life. Dynamic fatigue seam cracking and delamination may possibly happen in ionographic imaging member belts as well as in the intermediate image transfer belts.

The flexible electrophotographic imaging member belts are fabricated from a sheet cut from an imaging member web. The sheets are generally rectangular or parallelogram in shape. All edges may be of the same length or one pair of parallel edges may be longer than the other pair of parallel edges. The sheets are formed into a belt by joining overlapping opposite marginal end regions of the sheet. A seam is typically produced in the overlapping marginal end regions at the point of joining. Joining may be effected by any suitable means. Typical joining techniques include welding (including ultrasonic), gluing, taping, pressure heat fusing, and the like. Ultrasonic welding is generally the preferred method of joining because is rapid, clean (no solvents) and produces a thin and narrow seam. In addition, ultrasonic welding is preferred because the mechanical pounding of the welding horn causes generation of heat at the contiguous overlapping end marginal regions of the sheet to maximize melting of one or more layers therein. A typical ultrasonic welding process is carried out by holding down the overlapped ends of a flexible imaging member sheet with vacuum against a flat anvil surface and guiding the flat end of an ultrasonic vibrating horn transversely across the width of the sheet, over and along the length of the overlapped ends, to form a welded seam.

When ultrasonically welded into a belt, the seam of flexible multilayered electrophotographic imaging member belts may occasionally contain undesirable high protrusions such as peaks, ridges, spikes, and mounds. These seam protrusions present problems during image cycling of the belt machine because they interact with cleaning blades to cause blade wear and tear which ultimately affect cleaning blade efficiency and service life. Moreover, the protrusion high spots in the seam may also interfere with the operation of subsystems of copiers, printers and duplicators by damaging electrode wires used in development subsystems that position the wires parallel to and closely spaced from the outer imaging surface of belt photoreceptors. These closely spaced wires are employed to facilitate the formation of a toner powder cloud at a development zone adjacent to a toner donor roll and the imaging surface of the belt imaging member. Another frequently observed mechanical failure in the imaging belts during image cycling is that the ultrasonically welded seam of an electrophotographic imaging member belt can also cause initiation of cracks in the seam which then propagate and lead to delamination after being subjected to extended bending and flexing cycles over small diameter belt support rollers of an imaging machine or when due to lateral forces caused by mechanical rubbing contact against stationary web edge guides of a belt support module during cycling. Seam cracking and delamination has also been found to be further aggravated when the belt is employed in electrophotographic imaging systems utilizing blade cleaning devices and some operational imaging subsystems. Alteration of materials in the various photoreceptor belt layers such as the conductive layer, hole blocking layer, adhesive layer, charge generating layer, and/or charge transport layer to suppress cracking and delamination problems is not easily accomplished.

For example, when a flexible imaging member belt used in an electrophotographic machine is a photoreceptor belt fabricated by ultrasonic welding of overlapped opposite ends of a sheet, the ultrasonic energy transmitted to the overlapped ends melts the thermoplastic sheet components in the overlap region to form a seam. The joining techniques, particularly the welding process, can result in the formation of a splashing that projects out from either side of the seam in the overlap region of the belt. The overlap region and spashings on each side of the overlap region comprise a strip from one edge of the belt to the other that is referred herein as the “seam region”. Because of the splashing, a typical flexible imaging member belt is about 1.6 times thicker in the seam region than that of the remainder of the belt (e.g., in a typical example, 188 micrometers versus 116 micrometers).

The photoreceptor belt in an electrophotographic imaging apparatus undergoes bending strain as the belt is cycled over a plurality of support and drive rollers. The excessive thickness of the photoreceptor belt in the seam region due to the presence of the splashing results in a large induced bending strain as the seam travels over each roller. Generally, small diameter support rollers are highly desirable for simple, reliable copy paper stripping systems in electrophotographic imaging apparatus utilizing a photoreceptor belt system operating in a very confined space. Unfortunately, small diameter rollers, e.g., less than about 0.75 inch (19 millimeters) in diameter, raise the threshold of mechanical performance criteria to such a high level that photoreceptor belt seam failure can become unacceptable for multilayered belt photoreceptors. For example, when bending over a 19 millimeter diameter roller, a typical photoreceptor belt seam splashing may develop a 0.96 percent tensile strain due to bending. This is 1.63 times greater than a 0.59 percent induced bending strain that develops within the rest of the photoreceptor belt. Therefore, the 0.96 percent tensile strain in the seam splashing region of the belt represents a 63 percent increase in stress placed upon the seam splashing region of the belt.

Under dynamic fatiguing conditions, the seam provides a focal point for stress concentration and becomes the point of crack initiation which is further developed into seam delamination causing premature mechanical failure in the belt. Thus, the splashing tends to shorten the mechanical life of the seam and service life of the flexible member belts used in copiers, duplicators, and printers.

Since there is no effective way to prevent the generation of localized high protrusions at the seam, imaging member belts are inspected, right after seam welding belt production process, manually by hand wearing a cotton glove through passing the index finger over the entire seam length and belts found catching the glove by the protrusions are identified as production rejects. Both the time consuming procedure of manual inspection and the number of seamed belts rejected due to the presence of high seam protrusions constitute a substantial financial burden on the production cost of imaging member belts.

An advanced imaging member belt seaming technique has recently been successfully developed and demonstrated in recent years, by creating a puzzle-cut of male pattern at one end of an imaging member sheet and a matching puzzle-cut female pattern at the opposite end so that when butt joining them together by mating the puzzle-cut patterns and then secured the joint with application of an adhesive layer over it to form an endless flexible belt. Although this novel puzzle-cut seaming process represents a new breakthrough seaming technology and offers great promise, however the seam formed still has some physical, mechanical, and dimensional shortfalls yet remained to be overcome.

Therefore, there is an urgent need to provide seamed flexible imaging belts with an improved seam morphology which can withstand greater dynamic fatigue conditions thereby extending belt service life. It is also important, from the imaging member belt production point of view, that effective cutting of unit manufacturing cost of seamed imaging belts can be realized if an innovative post seaming treatment process can be developed for puzzle-cut seam joint improvement that overcomes the shortfalls and provides the triple benefits of seam region thickness reduction, seam surface morphological smoothing, and good mechanical seam strength.

U.S. Pat. No. 5,552,005 to Mammino et al., issued Sep. 3, 1996, discloses a flexible imaging sheet and a method of constructing a flexible imaging sheet. The method of constructing a flexible imaging sheet comprises a step of overlapping, a step of joining, and a step of shaping. In the step of overlapping, a first marginal end region and a second marginal end region of a sheet are overlapped to form an overlap region and a non-overlap region. In the step of joining, the first marginal end region and the second marginal end region of the sheet are joined to one another by a seam in the overlap region. In the step of shaping, the overlap region is shaped to form a generally planar surface co-planar with a surface of the non-overlap region. The flexible imaging sheet comprises a first marginal end region and a second marginal end region. The first marginal end region and the second marginal end region are secured by a seam to one another in the overlap region. The first marginal end region and the second marginal end region are substantially co-planar to minimize stress on the flexible imaging sheet. Minimization of stress concentration, resulting from dynamic bending of the flexible imaging sheet during cycling over a roller within an electrophotographic imaging apparatus, is particularly accomplished in the present invention.

U.S. Pat. No. 4,410,575 to Obayashi et al., issued Oct. 18, 1983, discloses that textile fabrics are firmly lap welded to each other by superposing two end portions of one or two fabrics on each other while interposing a piece of a synthetic polymeric bonding tape between the superposed two end portions and by applying a high frequency wave treatment and/or heat treatment to the interposed portion of the bonding tape through at least one of the superposed end portions while pressing them, to melt the interposed portion of the bonding tape thereby lap welding the end portions of the fabric or fabrics to each other.

U.S. Pat. No. 4,883,742 to Wallbillich et al., issued Nov. 28, 1989, discloses a process for seamless and firm joining of the end and/or lateral areas of thermoplastically processible photosensitive layers, by which the end and/or lateral areas of one or more solvent-free and unsupported thermoplastically processible photosensitive layers are overlapped avoiding bubbles and with displacement of the air between the end and/or lateral areas, the total layer material is then heated under pressure and with joining of the overlapping end and/or lateral areas, and the resulting continuously joined photosensitive layer is then after treated and smoothed with shaping to exact size.

U.S. Pat. No. 4,532,166 to Thomsen et al., issued Jul. 30, 1985, discloses a welded web which is prepared by overlapping a first edge over a second edge, then applying heat necessary to bond the first edge with the second edge. The heating techniques may include ultrasonic welding, radio frequency heating, and the like.

U.S. Pat. No. 3,988,399 to Evans, issued Oct. 26, 1996, discloses heat recoverable articles which have an elongate S-shaped configuration, which later can be wrapped about a substrate. The articles comprise a molecularly oriented unitary polymeric layer which has been differentially annealed while restrained against dimensional change and crosslinking.

The disclosures of the foregoing U.S. patents to Mammino, Obayashi, Wallbillich, Thomsen and Evans are hereby incorporated by reference verbatim, with the same effect as though such disclosures were fully and completely set forth herein.

Moreover, the above-identified commonly-assigned co-pending application Ser. No. 08/721,418 to Edward L. Schlueter, Jr. et al., the disclosure of which earlier co-pending application is herein incorporated by reference, discloses producing an endless flexible belt using a punch and die. The disclosed punch and die have patterned edges in the form of a puzzle-cut pattern with extremely small nodes and kerfs. Moreover, the cutting tolerances of the patterned edges make it necessary to fix the punch with respect to the die so that there is no misalignment of the punch and the die between cutting operations.

While the above references disclose a variety of approaches to improve the seam of flexible belts, these disclosed approaches are either insufficient to meet the expectation, or often time introduce new set of undesirable outcomes. For example, puzzle-cut butt joined seam, based on intimate male-female puzzle pattern interlocking, though does provide a belt with a seam of nearly no additional thickness, however the seam is seen to pop open and separate when the butt joint puzzle-cut seam of the flexible imaging belt bends and flexes over small diameter belt support rollers, such as the 19 mm diameter roller, causing total seam separation. Attempts to apply a thin adhesive strip over the puzzle-cut seam joint to permanently secure the joint and resolve the seam bending induced popping problem has been successfully demonstrated, but the application of the adhesion does add significant thickness to the resulting puzzle-cut seam to thereby diminish the practical value of the seam.

Therefore, there is a need for an improved method for fabricating a flexible imaging member belt with a puzzle-cut seam having nil or reduced seam thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

shows a flexible belt

10

with a puzzle-cut seam

11

fabricated in accordance with the present invention.

FIG. 1A

shows the belt

10

and puzzle-cut seam

11

in greater detail.

FIG. 1B

is an enlarged view of the

FIG. 1

puzzle-cut seam

11

pattern used on both joining belt ends

103

and

105

of the belt material to provide interlocking fingers each having a neck portion

14

attached to a larger head portion

16

.

FIGS. 1C

,

1

D and

1

E are three possible representations of the

FIG. 1

puzzle-cut configuration.

FIG. 2

shows a cross-sectional profile of a narrow adhesive strip application over seam

11

of the belt

10

and apparatus

201

-

202

suitable for demonstrating one embodiment of the present invention.

FIG. 3

shows a cross-sectional profile of a narrow adhesive strip application over seam

11

of the belt

10

and apparatus

201

-

302

suitable for demonstrating a further embodiment of the present invention.

FIG. 4

shows a cross-sectional profile of seam

11

of belt

10

and apparatus

201

A-

302

A suitable for demonstrating a still further embodiment of the present invention.

FIG. 5

is a flow diagram of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Therefore, it is an object of the present invention to provide a method for fabricating an improved flexible electrostatographic imaging member belt which overcomes the above-noted deficiencies.

It is another object of the present invention to provide a process for flexible electrostatographic imaging member belt puzzle-cut seam joint treatment which yields a thinner seam morphology as well as improving its mechanical seam strength.

It is still another object of the present invention to provide a process for flexible electrostatographic imaging member belt puzzle-cut seam treatment which eliminates the need of an adhesion strip, yields a seam of nil thickness, and is free of fatigue belt bending induced seam popping/separation problem when the electrostatographic imaging member belt flexes over small diameter belt module support rollers during cycling belt function.

It is a further object of the present invention to provide a method for fabricating an improved flexible electrostatographic imaging member belt having a mechanically robust puzzle-cut seam and exhibiting good circumferential dimension tolerance as well as wrinkle free in the seam region.

It is a still further object of the present invention to provide a method for fabricating an improved flexible electrostatographic imaging member belt having a thin puzzle-cut seam and free of wrinkles in the region of the seam.

Referring now to

FIG. 1

, there is shown a flexible imaging member belt

10

with a first end

103

and a second end

105

, the two ends

103

and

105

being joined by a puzzle-cut seam

11

fabricated in accordance with the present invention. As shown, the length of flexible belt

10

extending between the two ends

103

and

105

is mounted on rollers

12

. A drawing similar to

FIG. 1

may be found in Lucille M. Sharf, Edward L. Schlueter, Jr., et al., “Puzzle cut seamed belt with bonding between adjacent surfaces by UV cured adhesive,” U.S. Pat. No. 5,487,707, issued Jan. 30, 1996, the disclosure of which U.S. patent is hereby incorporated by reference verbatim, with the same effect as though such disclosure were fully and completely set forth herein. It is noted that the same Edward L. Schlueter, Jr. is a named inventor both in the foregoing U.S. Pat. No. 5,487,707 and in the present application.

FIG. 1A

shows greater detail of a specific segment of the flexible belt

10

, particularly including the vicinity of the seam

11

. As shown therein, flexible belt

10

comprises parallel edges

1

-

2

and the seam

11

extending from one edge to the other edge, the belt seam

11

including a seam region including a puzzle-cut butt joint with an applied adhesive strip

109

over the seam joint, the adhesive strip comprising a thermoplastic polymer material having a fusing temperature.

Still referring to

FIG. 1A

, the flexible belt

10

has an outer belt surface

10

A, an inner belt surface

10

B, a first end

103

terminating in a first puzzle-cut pattern of fingers

113

, and a second end

105

terminating in a matching second puzzle-cut pattern of fingers

115

. As shown, the first and second puzzle-cut patterns of fingers

113

and

115

are arranged to mutually mate or join with each other.

It is noted that the present invention's fingers

113

and

115

correspond to the “nodes” of the earlier commonly-assigned co-pending application Ser. No. 08/721,418 to the present Edward L. Schlueter, Jr. et al, the disclosure of which earlier application is herein incorporated by reference.

Referring now to

FIG. 1B

, there is an enlarged view of the first puzzle-cut pattern of fingers

113

and the second puzzle-cut pattern of fingers

115

used to join the belt

10

material first end

103

and second end

105

. As shown, each of the first puzzle-cut pattern of fingers

113

and the second puzzle-cut pattern of fingers

115

comprises a series of necks

14

attached to corresponding heads

16

arranged to form male

13

and female

15

interlocking portions.

As discussed in greater detail below, in one embodiment, the first puzzle-cut pattern of fingers

113

comprises a series of alternating fingers, each finger forming a neck

14

and an attached head

16

, the head diameter greater than the neck width, the head diameter from 0.1012 mm to 1.0160 mm, and the second puzzle-cut pattern of fingers

115

comprises a series of alternating fingers, each finger forming a neck

14

and an attached head

16

, the head diameter greater than the neck width, the head diameter from 0.1012 mm to 1.0160 mm, such that the first and second puzzle-cut patterns of fingers are able to mate to form an endless belt

10

.

The following is a discussion of the interrelationship among the various belt

10

and material parameters involved in the mechanical integrity of the seam

11

. The mechanical integrity of the seam

11

was examined and analyzed for a number of configurations and in particular for the preferred configuration which involves finger heads forming parts of a circle and interconnecting via a neck on the opposite side. To determine the deflection under loading conditions, each such finger is treated as a beam fixed at the narrowest part of the neck joining the finger to the base and the deflection of each finger (head and attached neck) is calculated in terms of the orientation of the load relative to the beam. To assure that the seam

11

will not come apart under load, it is imposed that the maximum deflection of each finger, when the load, under worse conditions, is normal to the beam, would not exceed the thickness of the belt itself. Clearly, if the deflection of the finger is in excess of the thickness of the belt

10

, then the seam will come apart. Under the above brief analysis, a master relationship connecting a material parameter M typical of the configuration with a geometric parameter G such that the belt

10

will not come apart under loading is expressed by the following Equation (1):

M = \frac{1 - G}{{(1 + \sqrt{4 - \frac{1}{G^{2}}})}^{3}}

In this relationship M is a dimensionless quantity given by the following Equation (2):

\begin{matrix} M = \frac{4 {NR}^{3}}{{Et}^{4}} & (2) \end{matrix}

and G represents the ratio as expressed by the following Equation (3):

G=

2

R/W

(3)

where N is the total load per unit width (i.e., lbs./in.) acting on the belt, E is the modulus of elasticity of the belt material t, the thickness of the belt, R the radius of the circular head forming the seam, and W is the wave length of one whole period between two adjacent fingers. Equation (1) is a one-to-one relationship between the material parameter M and the geometric parameter G. Thus, given one of them we can find the other parameter. Furthermore, because of the dimensionless nature of these two parameters, a multitude of configurations are embodied in each pair of values satisfying Equation (1), by virtue of the fact that there is an infinite number of combinations of the variables involved in that particular pair of values of M and G. Inspection of the geometry of the finger shows that the structure is characterized by two main features: the shoulder, or that portion where there is interference between adjacent fingers, which supports the seam, and the neck of each finger which represents its strength under loading. The size of the shoulder should be sufficient to insure mechanical integrity of the seam without making the neck too small as to weaken its strength.

In this regard attention is directed to

FIGS. 1C

,

1

D and

1

E wherein it can be visually observed that the size of the neck in

FIG. 1C

is too small and the size of the shoulder in

FIG. 1E

does not provide sufficient interference contact while the geometry in

FIG. 1D

appears to be optimum. Table 1 below lists the various parameters for the identified belt characteristics. While all samples will function as noted above, a value of G of 0.6 is a good compromise. Many of the samples of course are impractical to implement relative to factors such as manufacturing ease, costs, stress tolerance, etc. Equation (3) shows that G can only vary between ½ and 1, the first value refers to the case when the shoulder is zero, and the second value pertains to the case when the neck of the finger is zero and the finger has no strength. Once either M or G is known the entire configuration becomes determinate with the help of the above Equations (1), (2) and (3) and other standard geometric relationships. Measurements on actual belts have generally confirmed the above analysis.

To illustrate the solution methodology, suppose a belt material of Young's modulus E=500,000 p.s.i. and thickness t=0.004 inch is subjected to a tension N=2.0 lb./in. of belt width. H is the perpendicular height between centers of one finger on one side of the seam and an adjacent finger on the opposite side of the seam. The solution possibilities are given in Table 1 below such that the seam will not come apart. If a value G=0.6 is chosen as a compromise between seam integrity and finger strength, we find

TABLE 1

Head Diameter,

D = 0.448 mm

Period,

W = 0.747 mm

Neck Width,

g = 0.299 mm

Finger Height,

H = 0.69696

G

1/M

D

W

g

H

.5000

2.000

1.0160

2.0320

1.0160

1.0160

.5100

5.5296

.7239

1.4194

.6955

.8665

.5200

7.7482

.6469

1.2440

.5971

.8246

.5300

9.7913

.5984

1.1290

.5306

.7968

.5400

11.7592

.5629

1.0424

.4795

.7755

.5500

13.6903

.5351

.9729

.4378

.7580

.5600

15.6054

.5122

.9147

.4025

.7429

.5700

17.5179

.4929

.8647

.3718

.7295

.5800

19.4383

.4761

.8208

.3448

.7174

.5900

21.3751

.4612

.7818

.3205

.7061

.6000

23.3363

.4479

.7466

.2986

.6956

.6100

25.3292

.4359

.7146

.2787

.6856

.6200

27.3614

.4248

.6852

.2604

.6760

.6300

29.4406

.4146

.6580

.2435

.6668

.6400

31.5747

.4050

.6328

.2278

.6578

.6500

33.7722

.3960

.6093

.2132

.6491

.6600

36.0424

.3875

.5872

.1996

.6405

.6700

38.3950

.3794

.5663

.1869

.6320

.6800

40.8411

.3717

.5466

.1749

.6236

.6900

43.3927

.3643

.5279

.1637

.6153

.7000

46.0632

.3571

.5101

.1530

.6070

.7100

48.8678

.3501

.4931

.1430

.5987

.7200

51.8235

.3433

.4769

.1335

.5904

.7300

54.9497

.3367

.4612

.1245

.5820

.7400

58.2687

.3302

.4462

.1160

.5736

.7500

61.8060

.3238

.4317

.1079

.5651

.7600

65.5913

.3174

.4176

.1002

.5565

.7700

69.6594

.3111

.4040

.0929

.5477

.7800

74.0510

.3048

.3908

.0860

.5388

.7900

78.8149

.2986

.3779

.0794

.5297

.8000

84.0090

.2923

.3653

.0731

.5204

.8100

89.7035

.2860

.3530

.0671

.5109

.8200

95.9840

.2796

.3410

.0614

.5012

.8300

102.9563

.2731

.3291

.0559

.4911

.8400

110.7522

.2666

.3173

.0508

.4807

.8500

119.5388

.2599

.3057

.0459

.4700

.8600

129.5306

.2530

.2942

.0412

.4588

.8700

141.0081

.2459

.2827

.0367

.4472

.8800

154.3451

.2386

.2712

.0325

.4350

.8900

170.0512

.2311

.2596

.0286

.4222

.9000

188.8397

.2231

.2479

.0248

.4086

.9100

211.7410

.2148

.2360

.0212

.3942

.9200

240.2999

.2059

.2238

.0179

.3787

.9300

276.9445

.1964

.2112

.0148

.3620

.9400

325.7211

.1860

.1979

.0119

.3436

.9500

393.9129

.1746

.1838

.0092

.3231

.9600

496.0860

.1617

.1684

.0067

.2997

.9700

666.2290

.1466

.1511

.0045

.2722

.9800

1006.3020

.1277

.1303

.0026

.2376

.9900

2026.1140

.1012

.1022

.0010

.1885

N, lb./in. = 2.0

E, p.s.i. = 500,000

t, in. = 0.004

To minimize any time out or nonfunctional area of the belt it is desirable to have the seam width be as narrow as possible. Further, this enables the seam to be indexed so that it does not participate in belt functionality such as the formation and transfer of a toner or developer image. Typically, the seam is from about 1 mm to about 3 mm wide.

With reference to the embodiment illustrated in

FIG. 1B

, the seam may be typically of the order of one inch wide on a belt which is 16 to 18 inches long depending on roll diameter, material modulus or other parameters and the post and head pattern may be formed from a male/female punch cut with each end being cut separately and subsequently being joined to form the seam with a roller similar to that used as a wall paper seamer rolled over the seam by hand to complete the interlocking nature of the puzzle cut pattern.

The two ends of the belt material are joined by physically placing them together in interlocking relationship. This may require the application of pressure to properly seat or mate the interlocking elements.

Thus, referring generally to

FIGS. 1A and 1B

, the belt

10

ends

103

and

105

are joined by means of mating puzzle-cut patterns of fingers

113

and

115

together. As a result of this joining, the now-mated first and second patterns of fingers

113

and

115

form a juncture

108

, which provides strong mechanical interlocking after mating to form an endless belt

10

.

Next, in accordance with the invention, an adhesive strip

109

is applied over the juncture

108

.

Subsequent steps of the invention are depicted in

FIGS. 2-3

.

Referring now to

FIG. 2

, there is shown a cross-sectional profile of the belt

10

together with apparatus

201

-

202

suitable for demonstrating one embodiment of the present invention. As shown, the adhesive strip

109

(a thermally activated material) is applied onto the outer belt surface

10

A to only sufficiently enough cover the juncture

108

. The adhesive strip

109

comprises an adhesive surface

109

A. There is also shown two elements

201

-

202

, the first element

201

comprising a compressing and heating element, and the second element

202

comprising a compressing element.

In accordance with the invention, the compressing and heating element

201

applies a first force to the adhesive surface

109

A while, simultaneously, the compressing element

202

applies an equal but opposing second force to the inner belt surface

10

B of the belt

10

at an area proximate to the juncture

108

. As a result of the foregoing opposing first and second forces, adhesive surface

109

A and part of inner belt surface

10

B near the juncture

108

are compressed together. While elements

201

and

202

continue to actively apply the foregoing compressing forces, the following events occur, in sequence:

First, compression and heating element

201

applies heat directly to the adhesive surface

109

A to heat up and soften or melt the adhesive strip

109

for a fixed heating period causing the adhesive material to flow into and fill the crevice between the mating first and second puzzle-cut patterns of fingers

113

and

115

and bond the interfaces of these fingers

113

and

115

, as well as promoting the adhesive to stick to the outer belt surface

10

A at the juncture

108

.

Second, after the above heating period, compressing and heating element

201

cools the adhesive strip

109

for a fixed cooling period.

Third, after the above fixed cooling period, a processor (not shown) determines when a puzzle-cut seam

11

resulting from the foregoing compressing, heating, and cooling applied to adhesive strip

109

is satisfactory.

If the puzzle-cut seam

11

is determined to be satisfactory, then elements

201

and

202

cease to apply the foregoing compressing forces, and the process of fabricating a flexible belt with a puzzle-cut seam is done.

Otherwise, if the puzzle-cut seam

11

is determined to be not satisfactory, then elements

201

and

202

will continue the processing cycle again, to apply the foregoing compressing forces, while the above heating, cooling, and determining steps repeat until the determining step determines that the puzzle-cut seam

11

is satisfactory. As above, once the puzzle-cut seam

11

is determined to be satisfactory, then elements

201

and

202

cease to apply the foregoing compressing forces, and the process of fabricating a flexible belt with a puzzle-cut seam is done. When the puzzle-cut seam treatment process needs multiple heat/cooling cycles to reach a satisfactory result, the cumulative treatment time is required, from effective belt production cost consideration, not to exceed 30 seconds.

In one embodiment, the above determining step includes a step of determining the total heating period during which the adhesive strip

109

has been heated.

In one embodiment of

FIG. 2

, the compressing pressure applied to adhesive strip

109

is between about 40 pounds per square inch and about 80 pounds per square inch.

In one embodiment of

FIG. 2

, the heat applied to adhesive strip

109

is at a temperature of between about 70 degrees Celsius, which is equivalent to 158 degrees Fahrenheit, and about 100 degrees Celsius, which is equivalent to 212 degrees Fahrenheit.

In one embodiment of

FIG. 2

, the total heating period during which adhesive strip

109

is heated is at the desired temperature of between about 5 seconds and 25 seconds.

In one embodiment of

FIG. 2

, the adhesive strip

109

has a width that is sized to only sufficiently enough cover the juncture

108

. In one embodiment, the width is approximately ranging from about 1 millimeter to about 10 millimeters.

In one embodiment, the cooling step is accomplished by cooling the compressing and heating element

201

with a cooling fluid.

In one embodiment, the cooling fluid is water.

In one embodiment, the flexible belt

10

comprises a photoreceptor belt.

In another embodiment, the flexible belt

10

comprises an electroreceptor belt.

In still another embodiment, the flexible belt

10

comprises an intermediate image transfer belt.

Referring now to

FIG. 3

, there is shown a profile of the belt

10

together with apparatus

201

and

302

suitable for demonstrating a further embodiment of the present invention.

Similar to the prior embodiment described immediately above, the adhesive strip

109

is applied onto the outer belt surface

10

A to only sufficiently enough cover the juncture

108

, the adhesive strip

109

comprising an adhesive surface

109

A. Element

201

comprises a first compressing and heating element. As well, element

302

comprises a second compressing and heating element.

After the adhesive strip

109

has been applied to the outer belt surface

10

A, the first compressing and heating element

201

applies a first force to the adhesive surface

109

A while, simultaneously, the second compressing and heating element

302

applies a second force to the inner belt surface

10

B at a point proximate to the juncture

108

. As a result of the foregoing first and second forces, adhesive surface

109

A and part of inner belt surface

10

B near the juncture

108

are compressed together. Simultaneously while elements

201

and

302

continue to actively maintain the foregoing compressing forces, the following events occur in sequence:

The first compressing and heating element

201

applies heat directly to the adhesive surface

109

A while, simultaneously, the second compressing and heating element

302

applies heat directly to the junction

108

and, in turn, to the bottom surface

109

B of the adhesive strip

109

, the combined heating provided by elements

201

and

302

thus heating the adhesive strip

109

for a fixed heating period.

After the above heating period, the first compressing and heating element

201

directly cools the adhesive surface

109

A while, simultaneously, the second compressing and heating element

302

directly cools the junction

108

and, in turn, the bottom surface

109

B of the adhesive strip

109

, the combined cooling provided by elements

201

and

302

thus cooling the adhesive strip

109

for a fixed cooling period.

After the above fixed cooling period, a processor (not shown) determines when a puzzle-cut seam

11

resulting from the foregoing compressing, heating, and cooling applied to adhesive strip

109

is satisfactory.

If the puzzle-cut seam

11

is determined to be satisfactory, then elements

201

and

302

cease to apply the foregoing compressing forces, and the process of fabricating a flexible belt with a puzzle-cut seam is done.

Otherwise, if the puzzle-cut seam

11

is not determined to be satisfactory, then elements

201

and

202

will continue the processing cycle to apply the foregoing compressing forces, while the above heating, cooling, and determining steps repeat until the determining step determines that the puzzle-cut seam

11

is satisfactory. As above, once the puzzle-cut seam

11

is determined to be satisfactory, then elements

201

and

202

cease to apply the foregoing compressing forces, and the process of fabricating a flexible belt with a puzzle-cut seam is done.

In the

FIG. 3

embodiment, compression and heating by elements

201

and

302

result in heating and softening or melting the adhesive strip

109

for a fixed heating period causing the adhesive material to flow into and fill the crevice between the mating fingers and bond the interfaces of these fingers, as well as promoting the adhesive to stick to the outer belt surface

10

A at the juncture

108

.

In one embodiment, the above determining step includes a step of determining the total heating period during which the adhesive strip

109

has been heated by the compressing and heating element

201

.

In one embodiment of

FIG. 3

, the compressing pressure applied to adhesive strip

109

is between about 40 pounds per square inch and about 80 pounds per square inch.

In one embodiment of

FIG. 3

, the heat applied to adhesive strip

109

is at a temperature of between about 70 degrees Celsius, which is equivalent to 158 degrees Fahrenheit, and about 100 degrees Celsius, which is equivalent to 212 degrees Fahrenheit.

In one embodiment of

FIG. 3

, the total heating period during which adhesive strip

109

is heated at a selected temperature is between about 5 seconds and about 25 seconds.

In one embodiment of

FIG. 3

, the adhesive strip

109

has a width that is sized to only sufficiently enough cover the juncture

108

. In one embodiment, the width is approximately in a range of from about 1 millimeter to about 10 millimeters.

In one embodiment, the cooling step is accomplished by cooling the compressing and heating elements

201

and

302

with a cooling fluid.

In one embodiment, the cooling fluid is water.

In one embodiment, the flexible belt

10

comprises a photoreceptor belt.

In another embodiment, the flexible belt

10

comprises an electroreceptor belt.

In still another embodiment, the flexible belt

10

comprises an intermediate image transfer belt.

After performing the process based on

FIG. 2

or

FIG. 3

, in one embodiment, a mechanical polishing step is performed to remove the adhesive from the outer belt surface

10

A and smooth out the seam profile, thus achieving nil differential seam thickness in the treated puzzle-cut seam. In this embodiment, it will be understood that, while adhesive material is removed from the outer belt surface

10

A to achieve the nil differential seam thickness, there substantially remains that portion of the adhesive material that has previously flowed into and filled the crevice between the mating first and second puzzle-cut patterns of fingers

113

and

115

and bonded to the interfaces of these fingers

113

and

115

.

Referring now to

FIG. 4

, there is shown a still further embodiment of the present invention. As shown, the puzzle-cut seam

11

is subjected to the compression/heating treatment process of elements of

201

A and

302

A in the same manners as that described in

FIG. 3

, with the exception that the adhesive strip

109

is not required and both the compression/heating elements

201

A and

302

A are reduced in cross-sectional area to have a width only sufficiently enough to cover juncture

108

. For good understanding, the basic difference between elements

201

A and

302

A in FIG.

4

and the corresponding elements

201

and

302

in

FIG. 3

is their respective shapes.

In the

FIG. 4

embodiment, compression and heating by elements

201

A and

302

A result in heating and softening the belt

10

thermoplastic material to cause contacting surface areas of the first and second puzzle-cut patterns of fingers

113

and

115

to fuse together to form the puzzle-cut seam

11

.

In one embodiment of

FIG. 4

, the compressing pressure applied to form seam

11

is between about 70 pounds per square inch and about 120 pounds per square inch. In one embodiment of

FIG. 4

, the heat applied to form seam

11

is at a temperature of between about 160 degrees Celsius, which is equivalent to 320 degrees Fahrenheit, and about 240 degrees Celsius, which is equivalent to 464 degrees Fahrenheit.

In one embodiment of

FIG. 4

, the total heating period required to form seam

11

, at the selected temperature, is between about 1 second and about 7 seconds.

Referring now to

FIG. 5

, there is shown a flow diagram of the present invention and the seam treatment process is carried out according to the steps below.

The steps of

FIG. 5

will vary somewhat depending on which embodiment of the invention is being practiced.

The following first description is based on

FIGS. 2 and 3

.

After starting, step

501

, the process goes to step

503

.

In step

503

, the first puzzle-cut pattern of fingers

113

and second puzzle-cut pattern of fingers

115

of belt

10

are joined to form the juncture

108

. The process then goes to step

505

.

In step

505

, an adhesive strip

109

is applied on the outer belt surface

10

A to substantially cover the juncture

108

, the adhesive

109

layer comprising an adhesive surface

109

A. The process next goes to step

507

.

In step

507

, the adhesive surface

109

A and the inner belt surface

10

B are compressed together at a point proximate to the juncture

108

. In one embodiment, the step

507

compressing forces of are applied by the compressing and heating element

201

and the compressing element

202

. In another embodiment, the step

507

compressing forces are applied by a first compressing and heating element

201

and a second compressing and heating element

302

.

While the step

507

compressing forces continue to be applied, the process goes to step

509

.

In step

509

, the adhesive strip

109

is heated for a fixed heating period. In one embodiment, the step

509

heat is applied by means of compressing and heating element

201

applying heat to the adhesive surface

109

A. In another embodiment, the step

509

heat is applied by means of compressing and heating element

201

applying heat to the adhesive surface

109

A and, simultaneously, compressing and heating element

302

applying heat to the junction

108

and, in turn, to the bottom

109

B of the adhesive strip

109

. In either embodiment, the adhesive strip

109

becomes heated. While the step

507

compressing forces continue to be applied, the process goes to step

511

.

In step

511

, the adhesive strip

109

is cooled for a fixed cooling period. In one embodiment, the step

511

cooling is applied by means of compressing and heating element

201

cooling the adhesive surface

109

A. In another embodiment, the step

511

cooling is applied by means of compressing and heating element

201

cooling the adhesive surface

109

A and, simultaneously, compressing and heating element

302

cooling the junction

108

and, in turn, the bottom

109

B of the adhesive strip

109

. In either embodiment, the adhesive strip

109

becomes cooled. While the step

507

compressing forces continue to be applied, the process goes to step

513

.

In step

513

, it is determined when the puzzle-cut seam

11

formed as a result of the foregoing adhesive strip

109

applying step

505

, compressing step

507

, heating step

509

and cooling step

511

is satisfactory.

When determining step

513

determines that the puzzle-cut seam

11

is not satisfactory, the process returns to step

509

, whereupon the heating step

509

, cooling step

511

, and determining step

513

are repeated.

Otherwise, when determining step

513

determines that the puzzle-cut seam

11

is satisfactory, the process goes to step

515

.

In step

515

, the compressing initially begun in the prior step

507

now ceases. The puzzle-cut seam

11

is now complete, and the process ends, step

517

.

In one embodiment, the determining step

513

includes a step of determining a total (cumulative) period during which the adhesive strip

109

has been heated.

In accordance with the present invention, the physically interlocked butt joined puzzle-cut end

103

comprising the first puzzle-cut pattern of fingers

113

and the end

105

comprising the second puzzle-cut pattern of fingers

115

are processed into a boned seamed flexible imaging member belt

10

, with puzzle-cut seamed joint

11

.

In practice, the heating step

509

raises the temperature of the adhesive strip

109

in the joint region

108

to a temperature of from about 2-20 degrees Celsius, which is equivalent to 3.6-36 degrees Fahrenheit, above the fusing temperature of the thermoplastic polymer material that comprises the adhesive strip

109

.

Also, the compressing step

507

combines with heating step

509

to flatten-out the adhesive strip

109

, to eliminate protrusion spots in the adhesive strip

109

, to reduce joint region thickness of the adhesive strip

109

, as well as fusing the adhesive strip

109

to the juncture

108

, thus resulting in a seamed flexible belt

10

.

The meaning of fusing temperature of thermoplastic polymer material is defined here as an elevated temperature at which the thermoplastic polymer material at the belt juncture

108

is adequately softened to fuse into one continuous material matrix when subjected to the specific compressing force applied by step

507

.

The following second description is based on FIG.

4

.

After starting, step

501

, the process goes to step

503

.

In step

503

, the first puzzle-cut pattern of fingers

113

and second puzzle-cut pattern of fingers

115

of belt

10

are joined to form the juncture

108

. The process then omits step

505

and goes directly to step

507

.

In step

507

, the outer belt surface

10

A and the inner belt surface

10

B in the vicinity of the juncture

108

are compressed together.

Next, while the step

507

compressing forces continue, the process goes in sequence to steps

409

,

411

and

413

.

In step

509

, the belt in the vicinity of the juncture

108

is heated for a fixed heating period.

In step

511

, the belt in the vicinity of the juncture

108

is cooled for a fixed cooling period.

In step

513

, it is determined when the puzzle-cut seam

11

formed as a result of the foregoing compressing step

507

, heating step

509

and cooling step

511

is satisfactory.

When determining step

513

determines that the puzzle-cut seam

11

is not satisfactory, the process returns to step

509

, whereupon the heating step

509

, cooling step

511

, and determining step

513

are repeated.

Otherwise, when determining step

513

determines that the puzzle-cut seam

11

is satisfactory, the process goes to step

515

.

In step

515

, the compressing initially begun in the prior step

507

now ceases. The puzzle-cut seam

11

is now complete, and the process ends, step

517

.

In one embodiment, the determining step

513

includes a step of determining a total (cumulative) period during which the juncture

108

has been heated.

In summary, there is provided a method in accordance with

FIG. 5

for fabricating a flexible belt

10

with a puzzle-cut seam

11

, the flexible belt having an outer belt surface

10

A, an inner belt surface

10

B, a first end

103

terminating in a first puzzle-cut pattern of fingers

113

, a second end

105

terminating in a matching second puzzle-cut pattern of fingers

115

, a length therebetween, the first

113

and second

115

puzzle-cut patterns of fingers arranged to be joined together, the method comprising the steps of:

in step

503

, joining the first and second puzzle-cut patterns of fingers to form a juncture

108

;

in step

505

, applying an adhesive strip

109

on the outer belt surface to cover the juncture, the adhesive strip comprising an adhesive surface

109

A;

in step

507

, compressing the adhesive surface

109

A and the inner belt surface

10

B together at a point proximate to the juncture

108

and, while compressing:

in step

509

, heating the adhesive strip

109

for a fixed heating period;

in step

511

, cooling the adhesive strip

109

for a fixed cooling period; and

in step

513

, determining when the puzzle-cut seam

11

formed by the foregoing joining, applying, compressing, heating and cooling steps is satisfactory.

Also, there is provided method in accordance with

FIG. 5

for fabricating a flexible belt

10

with a puzzle-cut seam

11

, the flexible belt having an outer belt surface

10

A, an inner belt surface

10

B, a first end

103

terminating in a first puzzle-cut pattern of fingers

113

, a second end

105

terminating in a matching second puzzle-cut pattern of fingers

115

, a length therebetween, the first

113

and second

115

puzzle-cut patterns of fingers arranged to be joined together, the method comprising the steps of:

in step

503

, joining the first and second puzzle-cut patterns of fingers to form a juncture

108

;

in step

507

, compressing the outer belt surface

10

A and the inner belt surface

10

B together in the vicinity of the juncture

108

and, while compressing:

in step

509

, heating the belt

10

in the vicinity of the juncture

108

for a fixed heating period;

in step

511

, cooling the belt

10

in the vicinity of the juncture

108

for a fixed cooling period; and

in step

513

, determining when the puzzle-cut seam

11

formed by the foregoing joining, compressing, heating and cooling steps is satisfactory.

In one embodiment, the equipment used to practice the present invention comprises an impulse heat sealing machine.

In one embodiment, the resulting puzzle-cut seam

11

is mechanically polished to remove the excess adhesive from the seam region surface to yield a resulting puzzle-cut seam joint having no added thickness. In one embodiment, polishing is done by applying abrasives to the joint surface.

The

FIG. 5

process results in a seamed flexible belt of nil seam thickness and free of belt ripples at the vicinity of the puzzle-cut seam joint. It will be understood that the

FIG. 5

adhesive applying step

505

is performed when the invention is practiced based on

FIGS. 2

or

3

, but omitted when the invention is practiced based on FIG.

4

.

In all embodiments of the invention, the compression, heating, and cooling cycles should be completed in less than 30 seconds based on effective belt production cost consideration as well as to yield good physical/mechanical and seam morphological results.

Further, there is provided a process for flexible electrostatographic imaging member belt puzzle-cut seam joint treatment which yields a thinner seam morphology as well as improving its mechanical seam strength.

Also, there is provided a process for flexible electrostatographic imaging member belt puzzle-cut seam treatment which eliminates the need of an adhesion strip, yields a seam of nil thickness, and is free of fatigue belt bending induced seam popping and separation problem when the electrostatographic imaging member belt flexes over small diameter belt module support rollers during cycling belt function.

Moreover, there is provided a method for fabricating an improved flexible electrostatographic imaging member belt having a mechanically robust welded seam and exhibiting good circumferential dimension tolerance as well as wrinkle free in the seam region.

Also, there is provided a method for fabricating an improved electrostatographic imaging member belt having a thin puzzle-cut seam and no wrinkles in the region of the seam.

Referring again to

FIGS. 2-3

, with cross-reference to

FIG. 5

, there is depicted in

FIGS. 2-3

the flexible belt

10

wherein the first belt end

103

and the second belt end

105

have been joined to form a juncture

108

, such belt-end joining being depicted in

FIG. 5

as step

503

and described in the originally-filed specification at page 10, lines 29-31; page 16, lines 7-8; and page 19, lines 5-6.

Still referring to

FIGS. 2-3

, with cross-reference to

FIG. 5

, there is depicted in

FIGS. 2-3

only a single (1) adhesive strip

109

that has been applied directly to the outer belt surface

10

A of the first and second belt ends

103

-

105

to cover the juncture

108

, such adhesive strip

109

applying being depicted in

FIG. 5

as step

505

and described in the originally-filed specification at page 11, lines 1-2; page 16, lines 9-11; and page 19, lines 7-8.

Still referring to

FIGS. 2-3

, there is no depiction therein of any adhesive strip being applied to the inner belt surface

10

B.

Also, referring generally to the disclosure of the originally-filed specification, including the drawing thereof, there likewise is no disclosure of any adhesive strip being applied to the inner belt surface

10

B.

As a result of the foregoing, therefore, those of ordinary skill in the art will understand that, at a time prior to both the following A-B:

A. The above step

503

of joining the first belt end

103

and the second belt end

105

(the first and second belt ends

103

-

105

comprising the first and second puzzle-cut patterns of fingers

113

-

115

) to thereby form the juncture

108

; and

B. The above step

505

of applying such adhesive strip

109

directly to the outer belt surface

10

A;

then, at such time, both the outer belt surface

10

A and the inner belt surface

10

B are devoid of any adhesive material.

While various embodiments of a method for fabricating a flexible belt with a puzzle-cut seam, in accordance with the present invention, have been disclosed hereinbove, the scope of the invention is defined by the following claims.

Number	Name	Date	Kind
3988399	Evans	Oct 1976	A
4050322	Moring	Sep 1977	A
4265990	Stolka et al.	May 1981	A
4410575	Obayashi et al.	Oct 1983	A
4430146	Johnson	Feb 1984	A
4532166	Thomsen et al.	Jul 1985	A
4883742	Wallbillich et al.	Nov 1989	A
5487707	Sharf et al.	Jan 1996	A
5552005	Mammino et al.	Sep 1996	A
5690769	Daigle et al.	Nov 1997	A

Method for fabricating a flexible belt with a puzzle-cut seam

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

CROSS-REFERENCE TO RELATED APPLICATIONS

US Referenced Citations (10)