DE1497220A1 - Spray charge assembly - Google Patents

Description

Dr. Expl

RANK XEROX LIMITED

37/41 Mortimer Street, London, W. 1, England

S g rünl adung s ano r dnung

The connection lies on the SeM et of xerography and concerns in particular an improved Sprühladangsanordming "which it allowed to axif a carrier surface or on a xerographic Electrostatic plate. To apply charge.

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"For the reproduction of images using xerographic processes is put in a pail on a xerographic plate that made of one coated with a photoconductive insulating material electrically conductive carrier, uniformly electrostatic Charge applied. The plate thus charged νά.rd then exposed according to the object to be reproduced, which is usually done using conventional projection methods served. As a result of this exposure of the xerographic plate, the individual plate sections are corresponding to the respective Discharge radiation density to a greater or lesser extent. This creates an electrostatic coating on or in the plate coating latent image which can then be developed using an electroscopic material. That electroscopic material remains due to the electrostatic Forces adhere to the plate in a pattern corresponding to the latent electrostatic image. That on this Formed powder image is then normally transferred to a support surface in such a way that the support surface is placed on the powder image and on the one that remains free Area of the support surface an electrostatic charge is applied; the xerographic powder image becomes, so to speak, in the process Electrostatically attracted and sticks to the support surface. The support surface is then used by the xerographic Plate separated. The one located on the support surface The xerographic powder image can now be fixed there by any suitable method, such as by exposure to heat will.

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The one before the exposure and one before the one for the purpose of transfer an image to be carried out electrostatic charge electrostatic charge to be carried out on the support surface The xerographic plate is generally produced by a spray charge dispensing arrangement causes an electrostatic charge of the order of 800 Y in each lall up to 1100 T on the corresponding surfaces. One An embodiment of an arrangement which can be used for these purposes and which emits a spray charge is documented in TJS Pat. 2,836 (Yyverberg) stated. There is only one of one in a lot a small distance from the surface to be charged electrical shielding carried discharge wire ■ to a High voltage source connected. Appropriate means are placed between the surface to be charged and the one spray charge dispensing arrangement achieved a relative movement, whereby the "surface in question is evenly charged electrically will.

It is known that the discharge threshold voltage and the Bnt-. charge current of a charged wire so of its thickness from that the discharge threshold increases with any increase in the thickness of the wire and that "the discharge current for any given voltage decreases with any increase in the thickness of the wire. In addition, the discharge threshold voltage and the discharge current are immediately passed through on the wire deposited dust and influenced by changes in the movement and in the * ionization state of the air surrounding the wire.

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In continuously working automatic xerographic duplicating systems, where cut for the support surface Sheet material, such as paper, is used on which the When transferring the powder xerographic image formed to the drum, a sheet tab assembly is used as disclosed in US Pat U.S. Patent 3,062,536 (Butkus) is indicated to be the support surface more reproduced by the xerographic drum Separate transfer of the figure. With this type of arrangement, the front edge of the support surface on the drum is applied a negative air pressure is made effective, which leads to the detachment of the leading edge of the support surface from the drum. the The support surface then loosens due to its own weight further from the drum. Although against the drum surface and the front edge of the support surface only impulsively for a short time Periods of time compressed air is directed, small amounts of the pigment are periodically removed by this forced air Drum surface or removed from the front edge of the carrier material. This discharged powder settles on various Individual parts of the xerographic system, but especially on ■ the discharge wire and the shield of the spray charge assembly, if this is in the transfer position of the xerographic Plant. This is on the discharge wire and pigment color powder that accumulates heavily on the screen, which can now be regarded as dust affects the performance of the wire used to generate a discharge and leads to an uneven transmission during transmission electrostatic charging of the support surface. .

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The main object of the present invention is therefore to improve the structure of arrangements emitting a spray charge so that an electrostatic charge can be applied evenly to a xerographic plate or to another surface »

Another object of the present invention is « a spray charge dispensing arrangement of such a type create that is particularly suitable for uniform operation in / automatically operating systems.

These and other objects of the invention are achieved through application a single discharge wire or a single discharge electrode that reaches a high voltage source. connected; the discharge wire used or the The discharge electrode used is covered by a conductive discharge * shielding which is of such a construction that the accumulation of Dust is confined to, carried and isolated from the discharge wire. The discharge wire is inside this conductive shielding of insulating blocks in such a way that he worn from tremors that lead to his damage would lead is protected. By this arrangement it is j It is possible to apply a voltage to the discharge wire which largely exceeds the charge surge voltage of the wire. Since the shielding is kept at ground potential, most of the discharged discharge current overflows directly the shielding is down and only a small part of the current effective in charging the plate or support surface.

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"'. ·. This arrangement further comprises" inen dust of similar. Type as the conductive shield in order to prevent the accumulation _s of dust on the discharging wire or the conductive shield additionally..' -

Further objects and features of the present invention emerge from the description below, in which on in Reference is made to the details shown in the drawings. Of the devices shown in the drawings shows Pig. 1 schematically shows the transfer position of an automatically operating xerographic very multiplication system, including a constructed according to the present invention, a Spray charge outgoing arrangement used to apply an electrostatic charge to one while moving the support surface coming into contact with the xerographic plate serves,

Fig. 2 is a plan view of the constructed according to the invention SprühladuK. ^ s ano r dnung,

Pig. 5 is a side view of the FIG. ^{5 1 Ig.} 2 sprayer arrangement shown,

Pig. 4 a cream of the crop in Pig. 2 from the line 4-4 shown there, KLg .. 5 is a sectional view of the in Pig. 2 from the line 5-5 shown there, Pig. 6 is a side view of another embodiment of a discharge wire attachment arrangement, I ¹ Ig. 7 is a top plan view of the in Pig. 6, the discharge wire mounting arrangement shown, and /

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S ¹ Ig. Figure 8 is a side view of yet another discharge wire attachment assembly. . . ■■ - ■■■,

In the following - Fig. 1 considered in more detail. As already mentioned" is in this Ügur schematically an automatically working one xerographic duplicating system in the image transmission position shown in the BildÜbertragungsstellB / i that before xerographic powder image formed on the xerographic plate electrostatically from this plate onto a support surface which> ■ formed by a suitably cut sheet of paper can be transferred.

As shown, there is a at the image transfer point Sheet feeding arrangement through which the sheets of the carrier material are processed according to the presence of a developed one Image on the plate surface of the xerographic Plates are fed one after the other »*

A xerographic plate 1 contains on one-electrically conductive Carrying a photoconductive layer or a light-receiving surface? in the present case, the xdrographic Plate the ITornr of a drum which rotates in the corresponding direction indicated by the arrow drawn is arranged. The drum surface thus takes successively a variety of procedural classifications, of which only the ■ Transfer position is shown.

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Sheets 2 are made of a suitable carrier material one after the other by means of 'feed rollers 3 and 4 of the xerographic . • fed into and in contact with a previously on the drum Drum formed xerographic powder image brought.

The transfer of the xerographic powder image from the drum surface on the 'consisting of the carrier material sheets happens under the influence of a spray charge arrangement 5, the is constructed according to the present invention and at / or immediately below the contact line between the carrier material and the rotating drum is arranged. During operation, that generated by the spray charge assembly leads electrostatic! field to the fact that the carrier material on the ground the electrostatic forces stick to the drum surface. As a result, the carrier material moves synchronously with the Drum and is in contact with this, live the attraction the substrate attached to the drum are electrostatic Forces also that form the xerographic powder image Pigment color particles are transferred from the drum surface to the surface of the carrier material, where they ultimately adhere stay.

Immediately behind the image transmission point there is one Stripping assembly or a paper discharge assembly 6 through which the sheets of carrier material are stripped or removed from the drum surface. This arrangement, which is of the kind like it is set out in U.S. Patent 3,062,536 (Rutkus), contains a variety of small diameter

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Openings made by a suitable pulsator or a other device a pressurized air-shaped liquid is supplied. The purpose of the pulsator "consists . in it, from the pressurized aeriform liquid Rays emanate through the exit openings and with the Surface of the xerographic drum to come into contact leave, slightly in the forward direction of the carrier material sheet, around. its leading edge from the drum surface strip off and she one with an endless belt or the like. Working transport device.

With this arrangement, pigment color particles can and will be either from the drum surface or from the surface the carrier material discharged. These loose pigment particles, that are still electrically charged are attracted to various internal elements of the assembly, including the an arrangement belonging to the wire which emits a spray charge and the shield.

The actual subject matter of the invention is considered below, as embodied in particular by the preferred embodiment of the invention shown in ligures 2 to 4 . will. According to this embodiment of the invention, the spray charge assembly 5 has a grounded conductive shield, preferably made of aluminum or stainless steel, the shield, designated as a whole by 10, generally has one

J-shaped cross section and includes a bottom wall 11 and seiik- _(right standing to the side walls 12 and 13. FIG.

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In the iä I ¹ Ig. 1 shown Ausführungsungsf ο in the invention, the side wall 13 is the standing in the next trouble to the Ab stripping device wall; thus the wall closest to the dust source is higher than the wall 12 provided for the purpose still to be "described.

Inside the shield is a high-voltage wire or a of any suitable corrosion-free material such as stainless Steel, "existing discharge wire 15, which is a uniform Outside and a diameter of a suitable size 'has, arranged and that at a considerably smaller distance from the bottom wall 11 than from either of the side walls 12 and 13. The discharge wire 15 may, for example, be about 9 »5 mm from the bottom wall 11 and at least 12 mm from each side wall be arranged remotely.

The discharge wire 15 extends between two of suitable Insulating material "existing blocks 16 and 20 and is attached to these; the "two blocks are at opposite one another." Ends arranged between the side walls 12 and 13 and there screwed on by means of screws 25. One end of the discharge wire is around the wacky part of a "Viß rkantes one Metal washer 26 wrapped around or clamped to it. This arrangement is, as the figure shows, by means of a through the metal washer Screw held in place in a preferably in the block the threaded hole is screwed in.

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At the other end the discharge wire 15 is attached in a similar manner "As shown in Figures 2 and 5, the see end of the wire is wrapped around or" attached to "a second metal washer 26, and in this position by one through it Metal washer series of through-running screw 25. The threaded part of the viewing hood 25 sits in a borehole located in the inclusion plate 28 and is very tight into a suitable threaded hole located in the outer end of the block 20 ". The protruding part of the connecting terminal bolt is designed accordingly for connection to a suitable conductor rail or to a source carrying high voltage. To prevent the wire from bending, it is preferably clamped between the washer and the associated block "in the embodiment described above".

As can be seen from Figures 2 and 4, the center line runs the twisted metal washers "ben 26 and the associated Screws 25 close to the center line of the blocks 16 and that is why the wire to be tensioned is largely in to keep the same distance from the side walls 12 and 15.

Each of the blocks 16 and 20 is longitudinally slotted and 21 strand, in which together with these blocks "formed bent pins 18 and 22" are located. This allows The discharge wire 15 made of a suitable material ends over the carcass ciiluß dielectric material "existing arc shells 29" attached will.

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Those made of a dielectric material and one J-shaped cross-section with Mehtbogenenscheraiungen have a wall provided with a suitable hole, in whose hole the pin located in the block, 16 "or 20

engages * The opposite wall of the relevant arch shield is * as shown in Figures 4 and 5, in the other slot of the associated block.

The spray charge assembly is supported at a suitable distance from the drum by a bracket 35 (not shown) which is suitably earthed to other elements of the xdrographic system. are screwed onto the nuts 31 for fastening the bracket. ■■,. '■ ·

Although the spray charge assembly described above is still dust ajreceive if they · in an area containing dust is operated, their differ from the previously known spray charge arrangements Operating characteristics with moderate dust accumulation only insignificantly. «This is due to the Shape of the shield 10 and the arrangement of the discharge wire in the shield. With this arrangement, the upper surfaces that absorb the most dirt are not critical. This means that the endangerment of the respective part of the shielding surface is inversely proportional to the distance from the wire, or, in other words, that the shielding shape whose in the closest surface to the wire is in /

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sololi one position "is that little congestion was added is relatively exposed to a Sohmuta accumulation f .. So that the bottom wall 11 of the shield 1G is the critical . tischste surface and on the side wall and the inner corner the. Shielding can collect dust without the ■ -. " Change the operating characteristics of the arrangement ·. It should be noted that the dust penetrating into an electrostatic suffering first is charged and then attracted to the nearest grounded surface. That side wall of the shield that the Sheet scraper 6 shields, i.e. the side wall 13 » is higher than the side wall .12 ^ To dust or moved by air To keep I-carb pigments and, in addition, uncritical surface areas to create for dust pick-up.

With the arrangement of the shield and the Wire, a simply constructed spray charge arrangement is created which is less sensitive to dust characterized by a high degree of efficiency this by appropriate shaping of the shield, according to the the dust is deposited on special surfaces. A surface, namely the bottom surface of the shield, can thus be relatively clean held and as the determining variable for the discharge wire 15 be used. ·

Although the arrangement described above for continuous operation in a dust-laden atmosphere 'is suitable without being' If there are significant changes in the operating properties, an And partially surrounding the conductive shielding can result

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• Additional surface area used to collect dust creating additional shielding can be provided. This increases the operating life of the spray charge dispensing arrangement extended before their operating characteristics change.

The above properties are enhanced by a second Shield 40 reached, which is placed around the shield 10 imt and one which largely corresponds to the porm of the shielding 10 Po rm has · Me shield 40 includes a bottom wall 41 and side walls 42 and 43 standing perpendicularly thereon. The land made of a suitable conductive material are coated with a thin layer of dielectric material such as Teflon PEP, one sold by DuPont Corporation Product made of fluorinated ethylene / propylene coated. Satisfactory results are about 0.012 to 0.025 mm thick coatings of this material have been achieved. These insulated shield is after it is around the conductive shield 10 is arranged around by the discharge crystalite charged. From the freestanding and now charged Surface areas of the insulated shield are also

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Dust particles - attracted even before they hit the surface the shield 10 can be tightened. The isolated shield therefore cannot be viewed as an extension of the side and bottom walls of the conductive shield.

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The enclosure 40 is "fastened and" in a suitable manner studs directed away from the bottom wall 11 of the shield 10 14 movably arranged. Here are on the Crewinde- ' parts of the suitable one located in the bottom wall 41 ' Openings extending through the pin bosses 14 nuts 31 unscrewed, by means of which the shield 40 can be raised or lowered with respect to the shield 10 * Between 'the Bottom wall 11 of the shield 10 and the bottom wall 41 of the Shield 40 are screwed on the pin 14 coil springs 44 »which press the shield 40 against the nuts 31 and thus determine the height of this shield.

To prevent the Eat an electric arc from standing between the Clamping the discharge wire 15 and the xerographic plate or the carrier material are in the spray charge arrangement according to the invention appropriate shields provided. With the previously known devices it has now been shown; that an arc is formed even when the discharge wire is jolted, i.e. if there is a through on the wire the voltage applied to these forms the vibration generated.

As the arcing · determining functional quantities the wire tension, the amplitude and the frequency of the wire oscillation viewed. JPerner is believed that the an electrostatic field generated by the discharge wire Self-excitement takes place. This view is thereby sub- * supports that the excitation with the natural frequency of the wire and fundamentally takes place at any time.

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The exact course of the excitation of the wire Forces can only be guessed. Due to this fact, if the deflection of the discharge wire from the The rest position can be kept small »the light / double-voltage ohmic wave be increased, or conversely it could prevent arcing for a "certain operating voltage level will.

The following are the three shown in Figures 2, 6, 7 and 8 different, embodiments .the serving to reduce wire vibrations and thus an arc formation Wire "fastening arrangements considered in more detail. The wire vibrations can be done by offsetting the wire attachment point at one end on the surface of the insulator. girderbloekes and be reduced by point fastening of the other end of the wire. As FIG. 2 shows, this can thereby can be achieved that the right end of the wire 15 in one sufficient distance from the inner edge or from the left edge of the block 20 is attached »on the opposite end the wire is attached near the inner edge or the right edge of the block 16, as indicated above.

In the embodiment shown in Figures 6 and 7 is the Wire 15 is attached to blocks 16a and 20a, which fulfill the same function as blocks 16 and 20, by means of clamping plates ^ 50, which are screwed to these blocks by screws 51

are. ■

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To achieve a complete fastening of the wire to it one end is this between a clamping plate 50 and the

clamped. Deökflache of the block I6a / and with its end around the Ansohluß-

. screw 52 put here. The inside or right edge the .Klemmplatte 50 is to the inside or reohten edge of the block 16a aligned. On the opposite side is the wire between a clamp plate 50 and the block 20a largely clamped behind the inner edge of this block. For the sake of simplicity, the one forming on the wire is Oscillation wave as full oscillation through dashed lines Lines indicated. These lines "are intended to make it clear that the Wire 15 out of its .represented by the strongly drawn line Rest position is deflected, longitudinal vibrations of the Wire 15 are eliminated by mechanical damping.

This is done by changing the moment of wire contact point on the surface of the block 20a achieved what that A phase and frequency change occurs in successive Results in semi-oscillations. If "for example

'the wire moves in the upward direction, then the be * - points of contact of the wire formed by points A and 0, while in the pail that the wire moves in the downward direction

- move away, change the points of contact and through the points BundC are formed.

A reduction of the wire oscillation amplitude can also? be achieved successfully by that on the one hand a block 20b having a curved surface and on

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"".. a point fastening is used on the other side, like this in fig. 8 is shown. The left end of the wire 15. is attached in the same way as "shown in the embodiment according to FIGS. 6 and 7". The right one Block 2Qb "has a curved surface on which the wire is fastened by a clamping plate 50 and screws 51 in such a way that it ends at the terminal screw 52. The mode of operation the embodiment is similar to that described earlier in "FIG ligures 6 and 7 shown embodiment, if you look at the last embodiment considered the borderline case that the radius of the curved "surface of the block 20b in its Size a ^ n approaches infinity. In the lobes of the curved surface of block 20 b is the change in point contact of the wire infinitely large at this end. This means that the frequency change and the phase change of the oscillation is also infinite are large, what a partial but sufficient elimination the self-excitation of the wire 15 is important, and that in this respect only a slight change occurs when the wire becomes dirty with dust.

The invention has been explained above on the basis of a few exemplary embodiments, but it is, should be noted here, not limited to the details explained or to the particular conditions specified in detail. Although the structure has been explained using terms such as bottom and side wall and a special mounting arrangement, it should be noted that the spraying arrangement can be in any position on the front surface of the xerographic drum. _{g Q g ft} , _{g / ag} " _{2 ßAD}

For example, if ^ the spray charge arrangement is not in the
If the lowest position shown but were arranged in the uppermost position, then the bottom wall of the conductive shield could be viewed as a top wall * This application possibility is, that is to say here, as well as further modifications or changes within the scope of the present invention.

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Claims (1)

Claims OK 'h Spray charge arrangement, characterized by one of a Eodenwand (11) and side walls (12,13) standing perpendicular to it . Existing conductive shield (10), one side wall (13) of which is significantly higher than the other, due to opposite Ends of this shield (10) between the side walls (12,13) delegated insulating support blocks (16,2O), by one to the two insulating support blocks (16.2O) attached and in substantial arranged insulated from the bottom wall (11) than from the side walls (12, 13) of the conductive shield (10) Discharge wire (15), and through at one end of the discharge wire (15) arranged devices (28,52), which a_ji a high voltage source can be connected. . Spray charge arrangement according to claim 1, characterized by an arc shields connected to the insulating support blocks (16,2O) (29). Spray charge arrangement according to Claim 1 or 2, characterized in that that the discharge wire (15) on the one insulating block (20,20a, 20b) by means of an offset point attachment , and on the other insulating block (16, 16a) by means of a point attachment is attached » Spray charge arrangement according to one of claims 1 to 3, characterized by one. A second shield (40) comprising a surface coating of a dielectric material surrounding the first conductive shield (1O) is arranged around. 909819/0 992