Adjustable paper jam responsive device for an electrostatic copier

Abstract

In an electrostatic copier of the type which includes a fuser having a heating element for bonding a developed graphic image formed on a sheet of paper to the paper, disabling apparatus including a switch for electrically connecting and disconnecting the heating elements to the copier's local source of supply of power and a grating pivoted to the fuser for operating the switch in response to a paper jam within the fuser to disable the heating elements, there is provided an adjustable weight, attached to the grating, which is constructed and arranged to be sufficiently adjustable to permit the grating to be pivoted both in and out contact with the switch. With this arrangement the weight of the grating on the switch may be easily adjusted to a predetermined weight level, of for example 20 grams or less, to ensure movement of the grating by a sheet of paper which comes into contact with the same while being heated, thereby ensuring that the switch will be opened by the paper to disable the heating elements.

Description

BACKGROUND OF THE INVENTION

Electrostatic copying machines or copiers, of the type which perform processes wherein an electrostatic latent image formed on a photoconductor is developed by contacting the same with a dry developer material, and wherein the developed image is subsequently transferred from the photoconductor to a suitable sheet of paper, generally utilize a dry developer material of the type which has a toner component including a thermally metable resin, mixed with a suitable toning pigment, to facilitate thermally bonding the otherwise easily movable and smudgeable, transferred, developed image to the paper. Accordingly, such copying machines generally include a suitably heatable enclosure, wherein the paper and thus the developed image thereon is typically heated to a temeprature level of from 100.degree. to 300.degree.C for bonding the developed image to the paper, before the paper is further processed and/or discharged from the machine.

In one known copier there has been provided image bonding apparatus of the aforesaid type, generally referred to as a fuser, which includes an enclosure having an electrically energizeable heating element mounted for heating the paper as it moves through the enclosure in a predetermined path of travel. To avoid fires resulting from paper moving out of its predetermined path of travel and remaining in the enclosure, the fuser has been provided with a switch, normally held closed, which is openable to prevent electrical energization of the heating element; and a grating pivoted to the enclosure, and normally disposed to hold the switch closed, which is movable in response to the paper becoming jammed against the same to open the switch, thereby deenergizing the heating element.

In the course of investigating a paper fire in a fuser of the type described, it was found that the fire probably occurred due to the paper contacting but not moving the grating, or due to the paper jamming against the grating but failing to move the same with sufficient rapidity to operate the switch before combustion of the paper. Accordingly:

An object of the present invention is to provide an electrostatic copier including improved apparatus for bonding a developed image to a sheet of paper; and

Another object is to provide improved apparatus for disabling energization of the heating means of a fuser in response to a sheet of paper becoming jammed within the fuser.

SUMMARY OF THE INVENTION

In an electrostatic copier of the type which includes a fuser having heating elements for bonding a developed graphic image formed on a sheet of paper to the paper, the invention resides in providing improved means for disabling operation of the heating elements in response to the sheet of paper becoming jammed within the fuser. The prior art disabling apparatus includes a switch for electrically connecting and disconnecting the heating elements to the copier's local source of supply of power. In addition, the prior art disabling means includes a grating pivoted to the fuser for operating the switch. The grating normally holds the switch closed, but in response to a paper jam within the fuser, the grating opens the switch to disable the heating elements. The improved disabling apparatus includes an adjustable weight, attached to the grating, which is constructed and arranged to be sufficiently adjustable to permit the grating to be pivoted by the weight out of contact with the switch, to facilitate thereafter adjusting the weight to pivot the grating into contact with the switch. With this arrangement the weight of the grating on the switch may be easily adjusted to a predetermined weight level, of, for example 20 grams or less, to ensure movement of the grating by a sheet of paper which comes into contact with the same while being heated, thereby ensuring that the switch will be opened by the paper to disable the heating elements.

BRIEF DESCRIPTION OF THE DRAWINGS

As shown in the drawings, wherein like reference numerals designate like or corresponding parts throughout the several FIGURES:

FIG. 1 is a schematic view of an electrostatic copier including improved means for disabling operation of the fuser heating elements in response to a sheet of paper becoming jammed within fuser;

FIG. 2 is an eenlarged, fragmentary view of the copier of FIG. 1, showing the fuser and the improved fuser heating elements disabling mean in greater detail; and

FIG. 3 is a cross-sectional view of the fuser of FIG. 2, taken substantially along the line 3--3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, an electrostatic copier or copying machine 10, of the type which may be improved in accordance with the present invention, generally includes suitable framework 12 for supporting the various components of the copier 10, including a photoconductor 13. The photoconductor 13 is made of a suitable strip of material having an outer surface 14 treated to exhibit photoconductive characteristics, and an inner surface 16.

To movably support the photoconductor 13 within the copier 10, the copier 10 includes a plurality of elongated rotatable idler shafts 18 about which the photoconductor 13 is suitably endlessly looped with its inner surface 16 disposed in engagement with the respective shafts 18. The idler shafts 18 are disposed parallel to one another and suitably secured to the framework 12 so as to longitudinally extend transverse to a desired path of travel 20 of the photoconductor 13. In addition, the copier 10 includes an elongated rotatable driven shaft 22 and suitable electrically-energizeable means 19 for driving the shaft 22. The driven shaft 22 is suitably secured to the framework 12 so as to extend parallel to the respective shafts 18 and rotate in engagement with the outer surface 14 of the photoconductor 13, for moving the photoconductor 13 in the aforesaid path of travel 20 past a charging station 24, imaging station 26, developing station 28, and transferring station 30.

At the charging station 24 (FIG. 1) the copier 10 includes a suitable corona charging device 31 and suitable electrically-energizeable means 32 for driving the device 31. The charging device 31 includes, for example, a pair of elongated high-voltage, charging electrodes 33 suitably spaced from the moving photoconductor 13 and oriented relative to the same so as to longitudinally extend transverse to the photoconductor's path of the travel 20, for depositing a uniformly distributed array of electrostatic charges 34 of suitable polarity on the photoconductor's outer surface 14.

At the imaging station 26 (FIG. 1) the copier 10 includes suitable means for providing the photoconductor 13 with information in the form of a graphic image 36 carried by a document 37 placed by the operator (not shown) on a glass platen 38 secured to the copier framework 12. To that end, the copier 10 includes a suitable light source 39, a pair of reflectors 40, a lens 41 and electrically energizeable means 42 adapted by well-known means to cooperate with one another for illuminating the document 37 and flash exposing the photoconductor 13 with light 43 modulated by the graphic-image 36. The graphic-image modulated light 43 causes the photoconductor 13 to conduct the dissipate sufficient charge 34 from the photoconductor's outer surface 14 to provide the same with a developable electrostatic latent image 44.

At the developing station 28 (FIG. 1) the copier 10 includes a suitable container 46 for locally holding a reusable supply of developing material 48, a suitable developer material transporting device 50 and suitable electrically-energizeable means 51 for driving the device 50. The transporting device 50 comprises, for example, an elongated rotatable shaft 52 and an elongated magnet 54 magnetically coupled to one another. The magnet 54 and shaft 52 are located on opposite sides of the photoconductor 13 and suitably secured to the framework 12 so as to longitudinally extend parallel to one another, out of contact with the moving photoconductor 13 and transverse to the photoconductor's path of travel 20. The rotating shaft 52 carries developer material 48 from the container 46 into a suitably narrow space 56 between the shaft 52 and photoconductor surface 14, wherein the magnetic field 57 between the shaft 52 and magnet 54 brings carried developer material 48 into contact with the moving photoconductor 13. As a result, some of the toner material of the carried developer material 48 adheres to the latent image 44 so as to render the image 44 visible; thereby forming a transferable, developed image 58 on the outer surface 14 of the moving photoconductor 13.

The developed image 58 (FIG. 1) is then transferred from the photoconductor surface 14 to a suitable supporting substratum, such as a sheet of paper 60 having an outer surface 62 and an inner surface 64. To feed the paper 60 to the transferring station 30 the copier 10 includes suitable means such as an elongated, rotatable, driven shaft 66 and electrically-energizeable means 67 for driving the shaft 66; and an elongated, rotatable, idler shaft 68. The shafts 66 and 68 are oriented so as to longitudinally extent parallel to one another and transverse to the path of travel 20 of the moving photoconductor 13. The shafts 66 and 68 are respectively suitably secured to the framework 12 for rotation in engagement with the sheet of paper 60, to move the paper 60 in a desired path of travel 70 to the transferring station 30.

At the transferring station 30 (FIG. 1) the copier 10 includes an elongated, rotatable, idler shaft 72, which is suitably secured to the framework 12 so as to longitudinally extend parallel to the shafts 66 and 68 and transverse to the respective paths of travel 20 and 70 of the moving photoconductor 13 and sheet of paper 60. The rotating shaft 72 is disposed in engagement with the inner surface 64 of the moving paper 60, and in sufficiently close proximity to the moving photoconductor 13 to forceably urge the outer surface 62 of the paper 64 into sufficiently intimate engagement with the image bearing outer surface 14 of the moving photoconductor 13 to transfer toner from the developed image 58 to the paper 60. As a result, a developed graphic image 74 is formed on the outer surface 62 of the paper 60. Preferably the shaft 72 is additionally electrically energized by suitable means to aid in the transfer of toner from the developed image 58 to the paper 60.

The graphic image 74 (FIG. 1) is thereafter fused to the paper 60 through the application of heat to the image 74. To that end, the copier 10 includes an image bonding device known in the art as a fuser 76. The fuser 76 is suitably secured to the framework 12 and includes an insulated enclosure 78 having a base portion 80, top portion 82 and oppositely disposed side walls 83 (FIG. 2) arranged to define a heatable space 84. The fuser 76 has as inlet 86 and an outlet 88, and, to heat the enclosure space 84, heating means such as a pair of elongated, electrically-energizeable, infrared heating elements 90 suitably secured to the top portion 82 and electrically connected in parallel to one another via conducting means 91. Further, the fuser 76 includes a movable belt 92, an elongated, rotatable idler shaft 94, an elongated, rotatable driven shaft 96 and suitable electrically-energizeable means 97 for driving the shaft 96. The shafts 94 and 96 are suitably secured to the fuser 76 so as to longitudinally extend parallel to one another and to a desired path of travel 98 of the sheet of paper 60 within the enclosure 78; and the belt 92 is endlessly looped about the shafts 94 and 96 for moving the paper 60 in the desired path of travel 98.

The copier 10 (FIG. 1) also includes a suitable internal source of supply of electrical power 100, adapted by well-known means to be energized from an external source of input power 112, and a control circuit 114 for controlling energization of the various electrically energizeable means, 19, 32, 42, 51, 67, 91 and 97, from the energized power source 100. The control circuit 114 generally includes switching means such as a master switch 116 for energizing and deenergizing the copier 10, and suitable printing logic circuitry 118 for controlling formation of the developed image 74 on the paper 60.

The master switch 116 is a two position manually-operable switching device including first, second, and third normally open switching contacts 120, 122 and 124.

The first switching contact 120 (FIG. 1) is electrically connected via conducting means 126 between the internal power supply and the printing logic circuitry 118 in a circuit arrangement such that in the closed and open positions of the master switch 116, the power supply 100 and logic circuitry 118 are respectively electrically connected to and disconnected from one another via switching contact 120 for respectively energizing and deenergizing the printing logic circuitry 118. The printing logic circuitry 118 includes a manually operable, normally open, two-position switch including switching contact 128. In the closed position switching contact 128 connects the remainder of the printing logic circuitry 118 via conducting means 129 to a suitable potential level such as ground level 130 for starting operation of the energized print logic circuitry 118, and in the open position the switching contact 128 disconnects the logic circuitry 118 from ground level 130 for stopping operation of the energized printing logic circuitry 118.

The second switching contact 122 (FIGS. 1 and 2) is electrically connected via conducting means 132 between the power supply 100 and belt driving means 97 in a circuit arrangement such that in the closed and open positions of the switch master switch 116 the power supply 100 and belt driving means 97 are respectively electrically connected to and disconnected from one another via switching contact 122, for respectively energizing and deenergizing the belt driving means 97.

The third switching contact 124 (FIGS. 1 and 2) is electrically connected via conducting means 134 in a circuit arrangement such that in the closed and open positions of the master switch 116 the power supply 100 and conducting means 91 are respectively electrically connected to and disconnected from one another via switching contact 124 for respectively energizing and deenergizing the fuser heating elements 90.

In a prior art copier 10 including a fuser 76 of the type hereinbefore described, the fuser space 84 is typically heated to a temperature level of from 100.degree.to 30.degree.C for bonding the developed graphic image 74 to the paper transported 60 as the paper 60 is through the fuser 76 on the moving belt 92. To avoid fires resulting from a sheet of paper 60 moving out of its predetermined path of travel 98 within the fuser 76, the fuser has heretofore been provided with means for disabling energization of the heating elements 90 in response to a sheet of paper 60 becoming jammed within the enclosure 78.

In accordance with the prior art the aforesaid heating element disabling means includes a switch 140 (FIGS. 1 and 2) suitably fixedly secured to the fuser enclosure 78 and electrically connected via conducting means 142 between the heating elements 90 and power supply 100, and in series with the master switching contact 124, in a circuit arrangement such that in the closed and open positions of the switch 140 the power supply 100 and heating elements 90 are respectively electrically connected to and disconnected from one another via the switch 140; for respectively enabling and disabling energization of the heating elements 90 from the power supply 100 when the master switching contact 124 is closed. To open and close the switch 140, the switch 140 includes an externally operable button member 141. In addition, the heating element disabling means includes a grating 146 (FIG. 1) comprising a generally rectangularly-shaped lattice work of elongated rods extending in a plane above, and substantially parallel to, the path of travel 98 of the moving sheet of paper 60 to obstruct movement of the paper 60 out of the path of travel 98 and towards the heating elements 90. The grating 146 (FIGS. 2 and 3) includes a pair of parallel-spaced, front and rear end rods, 148 and 150, extending transverse to the path of travel 98 of the moving sheet of paper 60; and a plurality of non-parallel, spaced, mid-portion rods 152 extending in the direction of the path of travel 98 of the moving paper 60 and between the front and rear rods 148 and 150, to which they are suitably fixedly secured, as by welding. The rear grating rod 150 includes opposite end portions 154 (FIG. 3) extending through appropriately sized and shaped openings, 156 and 158, respectively formed in the fuser's top portion 82 and opposite side walls 83, to pivotally attach the grating 146 to the fuser enclosure 78 for movement in and out of contact with the switch 140. For switch contacting purposes the grating 146 preferably additionally includes a small rectangularly-shaped metal tab 156 normally disposed in contact with the switch operating member 141. With this arrangement the grating 146 (FIGS. 1 and 2) is intended to be normally held in contact with the switch 140 by gravity, to hold the switch 140 closed, and to be movable out of contact with the switch 140 by means of a sheet of paper 60, to open the switch 140. Accordingly, the switch 140 and grating 146 are provided to cooperate with one another for disabling energization of the heating elements in response to a sheet of paper 60 becoming jammed within the fuser enclosure 78.

Due to the dimensions of the various structural components and sub-assemblies of fusers 76 varying from fuser 76 to fuser 76 in the course of mass producing the same, the gravity weight of the grating 146 at the grating tab 156 (FIG. 3), and thus the weight of the grating 146 on the switch operating member 141, radically varies from fuser 76 to fuser 76. As a result, in the course of operating some prior art copiers 10, sheets of paper 60 (FIG. 1) can come into contact with the grating 146 but fail to pivot the grating 146 sufficiently rapidly away from the switch operating member 141 to open the switch 140 before the paper 60 combusts.

According to the present invention, the above described problem is remedied by attaching an adjustable weight 160 (FIGS. 2 and 3) to the grating 146 so as to counterbalance most of the weight of the grating 146 about the pivot axis of the grating 146. The adjustable weight 160 includes an L-shaped metal member 162, preferably a metal rod, having one leg 164 thereof fixedly attached to one of the end portions 154 of the rear rod 150 of the grating 146, externally of the fuser 76, by means of a fastener 167 fixedly secured to the grating end portion 154 and member 162. The other leg 166 of the L-shaped member 162 extends rearwardly from the grating 146 and in a plane extending substantially parallel to that of the grating midportion rods 152, thereby tending to counterbalance the weight of the grating 146, on the switch operating member 141, about the pivot axis of the grating 146. In addition, the adjustable weight 160 includes a circularly, annularly-shaped, member 168, preferably made of metal, which is removably slidably mounted on the aforesaid other leg 166 of the L-shaped member 162 and fixedly positionable thereon by means of an adjustable fastener such as a set screw 170. Members 162 and 168 of the adjustable weight 160 are dimensioned such that when the weight 160 is attached to the grating 146, for example as hereinbefore described, it is possible to move the annularly-shaped member 168 sufficiently rearwardly on the L-shaped member's leg 166 to pivot the grating 146 out of contact with the switch 140, to open the switch 146, thereby disabling energization of the heating elements 90 from the power supply 100 via the main switching contact 124. This is done to facilitate thereafter adjusting the weight of the grating 146 on the switch 140 to a predetermined weight level, preferably of 20 grams or less, by moving the annularly-shaped member 168 forwardly on leg 166; to thereby ensure pivotal movement of the grating 146 by a sheet of paper 60 in the event that the paper 60 moves out of its predetermined path of travel 98 and into slight contact with the grating 146. With this arrangement, the gravity weight of the grating 146 on the switch 140 can be easily adjusted in the field by unskilled personnel.

In accordance with the objects of the invention there has been described an electrostatic copying machine including a heatable fuser including improved means for disabling operation of the heating means of the fuser in response to a sheet of paper becoming jammed within the fuser.

Inasmuch as certain changes may be made in the above described invention without departing from the spirit and scope of the same, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative rather than limiting sense. And, it is intended that the following claims be interpreted to cover all the generic and specific features of the invention herein described.

Claims

What is claimed is:

1. An electrostatic copier including means for forming a developed image on a sheet of paper, an enclosure within which the developed image is heatable for bonding to the sheet of paper, electrically energizable means for heating the developed image, a source of supply of electrical power from which the heating means is energizable, means for moving the sheet of paper in a predetermined path of travel within the enclosure, and means for disabling energization of the heating means in response to the sheet of paper becoming jammed within the enclosure, said disabling means comprising:

a. switching means for electrically connecting the heating means to the source and disconnecting the heating means therefrom;

b. a grating disposed to obstruct the passage of the sheet of paper out of said predetermined path of travel, the grating pivotally attached to the enclosure for movement in and out of contact with the switching means to respectively connect the heating means to the source and disconnect the heating means from the source, the grating being normally held in contact with the switching means by gravity and being movable out of contact with the switching means by the sheet of paper, and

c. an adjustable weight attached to the grating for balancing the weight of the grating about the pivot axis of the grating, and said adjustable weight adapted to be sufficiently adjustable to permit adjustment thereof for pivoting the grating both into and out of contact with the switching means to facilitate adjusting the weight of the grating on the switching means to a predetermined level ensuring pivotal movement of the grating by the sheet of paper in the event that the paper moves out of said predetermined path of travel and into contact with the grating.

2. The electrostatic copier according to claim 1 wherein the adjustable weight includes a member movably attached to the grating, said member being fixedly positionable relative to the grating for balancing the grating weight to said predetermined level on said switching means.

3. The electrostatic copier according to claim 1 wherein the adjustable weight includes an L-shaped member having one leg thereof fixedly attached to the grating and includes an annularly-shaped member fixedly positionable on the other leg for balancing the grating weight to said predetermined level on said switching means.

4. The electrostatic copier according to claim 1 wherein the predetermined level of grating weight on said switching means is not more than 20 grams.