MXPA98002447A - Tension control for a cleaning stage in a fuser sub-system of an electrofotograf printer - Google Patents

Abstract

The present invention relates to an architecture of a melter sub-system or merger in an electrophotographic printer or copier, which includes a web or web that cleans the fuser or merger roller. The frame is moved by a mechanism that allows a constant speed of the frame with respect to the surface of the fusing roller, without need for a separate motor or controller. The design can also compensate for changes in the friction coefficient between the fusing roller and the weft, as caused by large deposits of organic pigment collected in the cleaning frame.

Description

VOLTAGE CONTROL FOR A CLEANING FRAME IN ONE - • FUSER SUB-SYSTEM OF ONE AN ELECTROPHOTOGRAPHIC PRINTER Field of the Invention 5 The present invention relates to a melter or fusion sub-system as it would be in an electrophotographic copier or printer and specifically it relates to a roller structure by which an FT can be contacted. cleaning pattern with one of the rollers in the sub-system of fuser or merger. BACKGROUND OF THE INVENTION Fusing is an essential step in the well-known electrostatic printing or copying process. In the fusing stage, pigment powder is fixed Organic that has been imaged on a medium, such as a sheet of paper, typically by a combination of heat and pressure in the medium to form a permanent image. The basic architecture of a merger is well known: in essence, a pressure roller turns against a fuser roller, the sheet containing image passes through a point of contact between the rollers. The side of the medium having the image to be fixed typically faces the fuser roller, which is often supplied with a heat source, such as a heater by resistance, in its core. The heat combination of the REF: 26856 fuser roller and the pressure between the fuser roller and the pressure roller, fixes the organic pigment to form the permanent image. In most current fusing systems, a system is provided by which the fusing roller can be automatically cleaned and / or supplied with a lubricant or release agent. For high volume applications, the release agent typically is supplied from a open supply of liquid release agent, which is usually applied to the fusing roll through one or more donor rolls. In contrast, for medium to low volume applications, the cleaning and lubrication steps are provided to the surface of the fusing roll by a weft that moves against the surface of the fusing roll at a site generally away from the contact point. The weft provides a rough surface to remove excess organic pigment particles from the surface of the fuser roller, and also provides quantities of lubricant or release agent. As is well known, the function of the release agent is to prevent the sheets passing through the contact point from continuing to adhere to the surface of the fuser roller, which will cause a paper jam.

In general, in most systems that have a web or sheet to process the fuser roller or merger, the web is removed from a replaceable web and moves at a reasonably slow speed relative to the merging roller 5, such that the Movement of the fusing roll causes the surface of the fusing roll to rub against a small area of the weft. The relatively slow movement of the weave provides friction to the fuser roller and provides a supply of clean plot at a reasonable speed. A typical ratio of surface speeds for example in a 60 ppm printer is approximately 300 millimeters per second for the outer surface of the fusing roll, compared to a speed of 2 to 3 millimeters per minute for the movement of the plot. In most prior art designs of a weft feeder for a fusing sub-system, the weft is drawn from a supply roll and pulled by a pick-up roll. Typically, the roller The collection is moved slowly and the supply roller is at rest passively. Many structures have been proposed to provide the necessary slow but continuous motion of the frame: specialty techniques include supplying an engine Externally separated from the motor that displaces the fusing roller, or provide a solenoid or ratchet structure. Another key practical problem with the weft feed architecture is that, as more and more weft is taken up by the pickup roller, the circumference of the pickup roller is significantly increased, and if the rotational speed of the pickup roller remains constant, the increase in circumference will cause a significant increase in the frame rate over the course of the frame duration.

This variation of speed is a source of performance variation that is undesirable and excessive speed wastes the frame. Another consideration that is crucial to the overall performance of a splicing web is the normal force between the web and the length of the merging roller. the normal force must be sufficiently high to allow the weft to remove, substantially by friction, particles of organic pigment in excess of the surface of the fusing roll, but not so high as to cause tearing of the weft, excessive tension of the The weft leads to a noxiously elevated pulse torque in the pickup roller, or another failure of the weft at the point of contact between a contact point roller and the fuser roller.

Description of the Prior Art The Patent of the U.S.A. No. 5,049,944, discloses an apparatus in which a cleaning web is displaced by a fuser roller control spring. A control system is used to vary the operation of the motor that moves the frame, such that there will be a relatively constant frame rate at the point of contact. The U.S. Patent No. 5,200,785 describes J fc. a sub-system merger in a replaceable cartridge. He The cartridge includes the fuser roller, a structure for oil application, a heating lamp, temperature detectors and an access opening. The electrical cartridge connector corresponds to an electrical receiver connector in the image forming apparatus. 15 The U.S. Patent. No. 5,212,529 discloses a fusing sub-system in which a frame is wrapped around a portion of the fusing roll. The frame contacts the merger on a relatively short wrapping angle, to reduce the torque required to move the fuser roller. A bypass mechanism increases the pressure applied to the frame in both the input and output areas of the merger. The U.S. Patent No. 5,495,276 describes a system for controlling the tension of a medium in which images are to be printed on a digital printer. A first roller moves the medium through the printer at a certain speed, while a second roller, placed after the first roller, moves the frame at a variable speed, whereby the variable speed has a maximum that is greater than the speed of the first roller. Energy is applied to the second roller through a clutch. When the maximum amount of jfjk. energy is applied to the second roller, the clutch limits the linear speed variable to that of the linear speed of the first roller. SUMMARY OF THE INVENTION In accordance with one aspect of the present invention, there is provided a fusion apparatus for an electrophotographic printer comprising a fusible roller or fusible merger, a contact point roller adjacent to a merging roller section, and a roller of collection. One end of a weft or web is connected to the pickup roller, with a portion of the web disposed between the first contact point roller and the fuser roll. A drive train causes rotation of the first contact point roller and pickup roller, the drive train includes a sliding clutch that limits a quantity of torque that the pickup roller can exert on the web.

According to another aspect of the present invention, there is provided a fusing apparatus for an electrostatic printer, comprising a rotatable fusing roller, and a contact point roller 5 adjacent to a stretch of fusing roller. of contact is placed in a mounting structure, the mounting structure is associated with a fulcrum and has an associated spring, such that the knitting roller of jH ^ contact is caused to exert a force of torque 10 against the melter roller or merger Brief Description of the Drawings Figure 1 is an elevation view showing the essential portions of a merger sub-system, as will be found in an electrostatic printer incorporating the present invention; simplified perspective view of a sliding clutch that may be employed in conjunction with the present invention, - Figure 3 is an elevation view showing the s essential portions of a merger sub-system, as would be found in an electrostatic printer showing another aspect of the present invention, and - Figure 4 is an elevation view showing the essential portions of a merger sub-system, as shown in FIG. would find in an electrostatographic printer that shows another embodiment of the present invention. Detailed Description of the Invention Figure 1 is an elevation view showing the essential portions of a fusion sub-system as it would be found in an electrostatic printer incorporating the present invention. A fuser roller 10 rotates in the indicated direction. The fuser roller 10 typically shares a contact point with a roller of pressure (not shown) through which passes a medium containing an image to be fused or fixed. At a point on the circumference of the fusion roller 10, a contact point roller 12 displaces a small area of a weft 14 against a length of the melting roller 10.

The segment of the weft 14 is extracted from a supply roll 16 and collected on a pickup roller 18. Further as illustrated in the Figure, what is referred to as a "wrapper" roller is provided.

. As illustrated, the wrapping roll 20 is configures with the contact point roller 12, such that an amount of the weft 14 is wrapped around a significant portion of the circumference of the contact point roller 12. In accordance with the preferred embodiments of the present invention, the The amount of wrapping of the weft 14 should be more than f 180 ° of the circumference of the wrapping roll 12, with a wrapping greater than 270 ° which is probably impractical from an architectural point of view. The significance of the wrapping roll 20 will be discussed in detail below. Also in the Figure is illustrated symbolically, by the dotted line marked with 24, is a "drive train", this is a structure such as a gearbox, pulley structure, or their combination, by the which the contact point roller 12, and the pickup roller 18 are commonly moved by a rotation source (not shown). This source of rotation can be a motor dedicated to displace the two rollers, or preferably it is the same motor that finally displaces the motor. fusion roller 10: the dotted line 25 symbolizes a common impulse structure, such as a gearbox, through which both the fusion roller 10 and a contact point roller 12 can be moved by a common motor. This structure of The displacement would have an approximate speed reduction of 3000-7000: 1 comparable with the speed reductions commonly employed in "clock motors". The pulse ratio between the contact point roller 12 and the pickup roller 18 of The preference is "rigid", constituted substantially by # gears and / or pulleys, with the significant exception of the presence of a sliding clutch here indicated, 26, the structure of which will be described in detail below. The presence of the pulse ratio 24 and 5 the sliding clutch 26 facilitates an important aspect of the present invention: The contact point roller 12 should move the weft against the surface of the fusion roller 10 at a constant speed, while maintaining the pickup roller 18 to a torque constant. This constant torque produces a predictably variable weft tension, as the diameter of the pickup roller 18 grows. While the maintenance of a constant speed on the contact point roller 12 is easily obtained by With an external motor, maintenance of a predictable variant tension of the web 14 is achieved by causing the pickup roller 18 to move to a constant torque. The constant torque on the pickup roller 18 and the ability to change its speed The rotational mechanism will prevent any problems from occurring by the gradually increasing circumference of the pickup roller 18. Figure 2 is a simplified view of a type of sliding clutch 26 that can be effectively placed. between the contact point roller 12 and the pickup roller 18. The sliding clutch 26 includes a helical spring 40 which is rigidly connected to the clutch output spindle 41, which in turn is rigidly anchored to the portion of the train pulse 24 towards the pickup roller 18. The connection of the coil spring 40, output clutch spindle 41 requires to be rigid only in the impulse direction of the weft. The coil spring 40 is displaced against, by virtue of the spring forces and the relative size of the coil spring 40. to the inner surface of a drum, illustrated in dotted lines as 42. The drum 42 is rigidly connected to the drive train portion 24 towards the contact point roller 12. Due to the various gears, pulleys, etc. (not shown) in the drive train 24, the rotation in the clutch 26 from the side of the contact point roller 12 is preferably at least 15% faster than what is required for an empty pickup roller ( minimum radius) 18 to move the frame 14 at the speed desired constant. As is generally known in the art of sliding clutches, when there is high demand for torque on the pickup roller 18, as will be explained below, the clutch output spindle 41 moves relative to the drum 42. Due to a winding Particular of the coil spring 40, when the coil spring 40 is rotated relative to the drum 42 in its winding direction, the total diameter of the coil spring 40 becomes smaller and thus substantially detaches from the inner surface of the drum 42. This lack of radial force between the coil spring 40 and the interior of the drum 42 limits the torque drive train 24 that can be exerted on the pickup roller 18, thus limiting the attention in the frame 14 to a range predictable: the torque divided by the minimum and maximum spokes of the pickup roller 18. Although a spring-type sliding clutch is illustrated here, other types of slip clutch such as magnetic are possible as equivalent for this purpose. The purpose of the wrapping roller 20, which maintains a relatively high proportion of the circumference of the contact point roller 12, wrapped in the frame 14, consists in maintaining a constant speed of the weft 14, deactivating the sliding between the weft 14 and the contact point roller 12. As illustrated in Figure 1, the tension t1 of the frame 14 at the indicated point is related to the voltage t2 at its point indicated by the equation: T2 = Txeaμ * where a is the wrapping angle of the weft 14 around the circumference of the wrapping roll 12, and μ is the coefficient of friction between the weft 14 and the surface of the contact point roll 12. A typical value of μ in this context is 0.3 to 0.55, depending on the different materials used. The frictional forces between the weft 14 and the fuser roller 10 caused by the loading of the roller Jff point of contact 12 against the fuser roller 10, the coefficient of friction of the weft 14 against the fusing roll 10, and the movement of the fusing roll 10, must be resisted by T2 or the framing 14 will move with the fusing roll 10. The friction coefficient of the framing 14 against the fusing roll 10 varies enormously (9.2-1.1) depending on the amount of organic pigment and grime in the weft 14. The strength of the knit roller F contact 14 against the fuser roll 10 may or may not change during use of the system, depending on the configuration. T1 varies predictably according to the pickup roller 18 changes radius and clutch 26 slides. In this way, when Tx is at a minimum (when the pickup roller 18 is full) and the frictional force of the fuser is a maximum, T2 must at least be as large as the frictional force or the weft 14 will already move with the fusion roller 10 or it will stop moving. Ensure that the wrapping angle a is above the threshold where T2 equal to the frictional force from the fusing roll, makes T2 large enough to ensure proper movement of the weft 14 against the fusing roller 10, giving the friction coefficient of the weft 14 against the contact point roller 12. Similarly, when T1 is at a maximum (minimum diameter of pickup roller 18) and the frictional force is at a minimum (very little pigment and grime and low load), the failure mode opposite may occur: the weft 14 will slide over the contact point roller 12. In this case, T2 is the sum of the frictional force between the weft 14 and the fuser roller 10 and the frictional force between the weft 14 and the roller of contact point 12 acting on the other side of the frame. (In the previous discussion T2 must resist the difference of these two frictional forces, but that detail can be omitted since the force on the side of the fuser roller dominates). In this fault mode T2 and? 1 are commuted in the equation, and the maximum tension is encountered which will not cause the frame 14 to slide on the contact point roller 12. Here again, more wrapping angle a is better . In this way, the wrapping roller 20 and the wrapping of the weft 14 around the contact point roller 12 increases the "latitude" of the system against variation in the diameter of the pickup roller 18, the friction coefficient of the weft 14 against the fuser roller 10, and the non-predictable load variation between the contact point roller 12 and the fuser roller 10. FIG. 3 is an elevation view showing another embodiment of the present invention. In Figure 1 and Figure 3, similar reference numbers indicate like elements, and the total function of the elements in Figure 1 is the same in the embodiment of Figure 3.

The embodiment of Figure 3 further includes an arrangement that at least the contact point roller 12 and preferably the other rollers 16, 18 and 20 are mounted on a structure, here indicated as plate 50, which in turn is assembled at least in a pivotal fulcrum here indicated as 52. Also connected to the structure 50 opposite the fulcrum 52 is a spring 54 which can be of any design, which has the effect of displacing the contact point roller 12 against the surface of the fusion roller 10, with a force Fg as seen from the own spring 54. The overall purpose of this structure is to allow compensation for frictional variations between the weft 14 and the fuser roller 10, by reducing the "normal" (radial) force between the contact point roller 12 and the fusion roller 10 according to your coefficient of friction increases. This variation in the frictional coefficient at this point is very common depending on how much organic waste pigment is caused to adhere on the surface of the fuser roller 10, when it is fixed to a particular image on the merging sub-system. In practical applications, the frictional coefficient can vary widely from 0.2 - to 1.1. Sudden changes in the friction coefficient will of course have a serious impact on the balance of the J jr system that tries to provide a constant speed in the frame 14. The operation of the fulcrum 52 and the spring 54 to compensate for the sudden changes in frictional coefficients in the fusing roller 10, is as follows. Figure 3 shows certain dimensions of which will be calculated at following various torques: rN represents the radius between the fulcrum 52 and the point of contact between the contact point roller 12 and the fusion roller 10 over the direction T, which is the direction of tension in the weft 14 , at the point of contact, - rs represents the effective radius between the fulcrum 52 and a select point from which the spring 54 exerts the force Fs; rt represents the radius between the fulcrum 52 and a line perpendicular to the point of contact formed by the fusion roller 10 and the contact point roller 12; and finally FN represents * the instantaneous normal force between the fuser roller 10 and the contact point roller 12. In a static case, where the rollers are not moving, the torque of the structure 50 (the force Fs by the radius with respect to a fulcrum 52) equal to the normal force exerted against the contact point roller 12 by the fusion roller 10 by its radius: Fsrs = FNrN # (The term that includes the effect of gravity on the mass 10 of the structure, has been omitted from this and all the subsequent equations, to simplify the concept). In the dynamic situation where the various rollers move and the friction of the fusing roller 10 is exerted against the weft 14 thus creating a tangential force in the weft, the torque equation is as follows: includes pulse torque feeding by pulse train 24, omitted here and subsequently subsequently for clarity, but would be less than 30% of the total load). The new tangential force Ft is equal to the normal force in FN in the frame by the instantaneous frictional coefficient μ (£ r, ran) between the surface of the fusing roll 10 and the frame 14, giving the equation: 25 Fs s = FNrN + FN (fr, tran) It will be noted in the above equation that the variable μ (fu ran) is the non-predictable variable that will depend on the amount of excess organic pigment in the fusing roll 10 at a particular time. Fs will change only 5 slightly, and in fact it will not change in fact, because usually there is only a small deformation of the spring 54. The various radio values are of course fixed. In this way, when the value μ (fr tcan) changes, the only * Variable that can compensate to maintain the equation is 10 FN. When rewriting the above equation, the value of FN varies as follows: N + (fr, tcan) rt In this way, the fulcrum 52 and the spring 54 of This embodiment of the present invention facilitates a weft feed system that can maintain a constant speed of the weft 14, independently of sudden changes in the frictional coefficient of the merger roller 10, over a wide range of conditions that are achieved with only the use of the wrapping roller 20. Figure 4 is an elevation view of the essential elements of an alternate embodiment of the present invention. In Figure 4, similar numbers represent similar elements as in Figure 1, with The difference is that instead of the web 14 being wound directly from a wrapping roller 20 to the pickup roller 18, the web 14 extends from the wrapping roller 20 around a roller 21 (or equivalent structure, such as a curved plate) to a second contact point roller indicated here as 60. After winding on the second contact point roller 60, the pattern 14 is picked up by the collection roller 16 as in the previously described modes. Typically, the second contact point roller 60 moves purely by the action of the frame 14 against it, but conceptually it can be moved by an impeller system equally. Roller 21 can alternatively be omitted altogether, allowing the weft 14 to slide on the picking spool 18 with a very slight speed mismatch or slightly stretched between the second contact point roller 60 and the pickup reel 18. In view of Figure 4, a point on the surface of the fusing roll 10, which moves in the indicated direction, first encounters the frame 14 in the second contact point roll 60, and then almost immediately thereafter, finds the frame 14 in the contact point roller 12. Several unique features are apparent in the configuration of Figure 4. First, the contact point roller 12 and the second contact point roller 60 have opposite sides, each side indicated respectively here as 14a and 14b (from the weft 14 to the surface of the fuser roll 10. This structure of course allows both sides 5 of a frame 14 to be used, which in turn can perm to perform a more effective cleaning of the fusing roller 10, or to allow the frame 14 to move at an even slower speed than in the previously described modes. In second, it is significant that in the first When the surface of the fusing roller 10 and the weft 14 meet, in the second contact point roller 60, the rotation of the two rollers is relative to each other, as opposed to the case with the contact point roller 12 rotating against the direction of rotation of the fuser roller 10.

A practical advantage of this structure is that, as the web 14 moves toward the pickup roller 18, the web material "downstream" of the point of contact between the second contact point roller 60 and the fuser roller 10, it will have already been used, and therefore will be dirty with organic pigment that has previously been removed from the fusion roller. Any excess organic pigment (more than that which can be maintained in the "pore" structure or roughness of the weft) removed frictionally from the fuser roll 10 tends to advance by rotating or otherwise moving through the point of contact when moving the merger roller 10. In the case of the rotation direction "with" the second contact point roller 60, this excess organic pigment encounters the organic pigment previously withdrawn in the dirty portion of the web 14. In other words, the pigment in the merger roller 10 passing through the contact point in the second contact point roller 60, will be pushed over the dirty organic pigment * that is already in the plot 14. As the organic pigment is always in some proportion electrostatically, attracts another organic pigment and the hot organic pigment is sticky and preferably adheres with another hot organic pigment, this structure increases the efficiency of total cleaning at the point of contact formed by the point of contact roll 60. While the invention has been described with reference to the structure described, it is not confined to the details set, but is intended to cover these modifications or changes that fall within the scope of the invention. scope of the following claims. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, the content of the following is claimed as property: ^ P F

Claims (8)

1. * CLAIMS 1. - A fuser apparatus for an electrostatic printer, characterized in that it comprises: a meltable roller or rotatable merger; a first point roller 5 contact, a length of the contact point roll is adjacent to a length of the fusing roll; a pickup roller; a weft, an end side of the weft is connected to the pickup roller, and a portion of the weft is disposed between the first weft roll 10 contact and the fuser roller; a drive train for causing rotation of the first contact point roller and pickup roller, the drive train includes a slipper clutch associated with the pickup roller, the slipper clutch limits an amount of torque of 15 twisting that the pickup roller can exert on the weft.
2. 2. - The apparatus according to claim 1, characterized in that the frame contacts the first contact point roller over an angle of 20 wrap at least 180 °.
3. 3. The apparatus according to claim 1, characterized in that the drive train, when associated with a source of constant rotational speed, causes the first point roller of 25 contact rotate at a constant rotational speed.
4. 4. - The apparatus according to claim 1, characterized in that the drive train also causes rotation of the fusing roll.
5. 5. - The apparatus according to claim 5, characterized in that the contact point roller is placed in a mounting structure, the mounting structure is associated with a fulcrum and has an associated spring, such that the roller knit * contact is caused to exert a torque force 10 against the fusion roller.
6. 6. A fusion device for an electrostatic printer, characterized in that it comprises: a rotatable fusible roller; a contact point roller, a section of the contact point roller is adjacent to a section of the fusion roller; the contact point roller is placed in a mounting structure, the mounting structure is associated with a fulcrum and has an associated spring, such that the contact point roller is caused to exert a torsional torque force 20 against the fuser roller.
7. 7. - The apparatus according to claim 6, characterized in that it also comprises a frame, a portion of the frame is arranged between the first contact point roller and the fusing roller; The frame contacts the first contact point of the contact point on a wrapping angle of at least 180 °.
8. 8. - The apparatus according to claim 6, characterized in that it further comprises: a frame, a portion of the frame is arranged between the first contact point roller and the fusing roller; a pickup roller, one end of the weft is connected to the pickup roller, - and a pulse train, to cause rotation of the pick roller. 10 contact and the pickup roller, the drive train includes a slip clutch associated with the pickup roller, the slip clutch limits a quantity of torque that the pickup roller can exert on the web. fifteen