MXPA97001128A - Apparatus for eliminating negatively charged triboelectric particles of a surface and method for cleaning such particles - Google Patents

Abstract

The present invention relates to an apparatus and method for cleaning residual particles of negatively charged triboelectric organic pigment from the photoreceptor surface. A positive polarization is applied to two electrostatic brushes in the double cleaning system or to an individual electrostatic brush. The rotational speed of the individual positive brush is increased, on that of the individual brushes in a double brush cleaner, to clean the triboelectric organic pigment particles with negative charge.

Description

APPARATUS FOR ELIMINATING NEGATIVELY CHARGED TRIBOELECTRIC PARTICLES OF A SURFACE AND METHOD FOR CLEANING SUCH PARTICLES BACKGROUND OF THE INVENTION This invention relates to an electrostatic printer or copier and more particularly relates to a cleaning apparatus for removing negative triboelectric organic pigment from an image forming surface. With greater use of the negative triboelectric organic pigment and printing and copying machines, a more efficient way is needed to remove these organic pigment particles from the image forming surface. The following descriptions may be important for various aspects of the present invention and may be briefly summarized as follows: US-A-5, 257, 079 to Lange et al. describes an electrically polarized cleaning brush with an alternating current that removes particles discharged from an image forming surface. The particles on the image forming surface are discharged by a device that generates a corona. A second cleaning device includes an insulating brush, a brush conducting REF: 23735 a blade, located upwards of the first brush mentioned, in the direction of movement of the image forming surface, further eliminates the particles deposited therein. US-A-4, 545, 669 to Hays et al. describes an apparatus for charging, displaying image forming groups at low voltages, comprising a flexible, deflected, semi-transparent image forming member, an electronic image forming source means, a light beam deflecting member, a medium containing magnets thereon, a developing roller means containing the magnets therein, a voltage source means for sensitizing the roller means, a voltage source for the developer roller medium, a developer supply reservoir containing in the conductive developer particles, consisting of insulating organic pigment resin particles and conductive carrier particles, a sensitization fastening point located between the sensitizing roller image forming member, a developing fastening point located between the forming member Developing roll image, sensitizing roller medium and developing roller medium moves n in the same direction or movement as the image forming member, flexible, deflected, semitransparent, the voltage is generated by the voltage source with the sensitization holding point which is of an opposite polarity from the voltage generated by the source of voltage for the developing roller, wherein an electric field of a predetermined polarity is established between the flexible, flexed, semitransparent image forming member and the sensitizing roller means, which exerts a field on the roller medium sensitization, which field exerts at the sensitization point an electrostatic force on the charged organic pigment particles causing these particles to migrate uniformly towards the image forming member, subsequently subduing the flexible image forming member, diverted to the image forming source electronics, so that the electrostatic force exerted on the particles those of organic pigment adjacent to the light shock areas of the flexible image forming member are augmented, whereby they cause the organic pigment particles to be deposited on the flexible, deflected, image-forming member and in which the particles of pigments are removed from the flexible, image forming member, deflected in areas not exposed to light by the developing roller and developed in the areas exposed to light.

BRIEF DESCRIPTION OF THE INVENTION Briefly stated and in accordance with one aspect of the present invention, there is provided an apparatus for removing the negatively charged triboelectric particles from a surface, the surface is capable of movement, comprising: a pre-cleaning corotron having a first polarity; and a first means of cleaning the triboelectric particles with negative charge, from the surface, having a second polarity different from the first polarity of the pre-cleaning corotron. According to another aspect of the present invention, a method for cleaning negatively charged triboelectric particles from a surface comprises: transferring an image to a printing medium; pre-clean the particles that remain after the transfer on the surface, using a negatively charged corotron; loading a first brush positively to remove both the triboelectric particles, with negative charge, which have as the triboelectric particles, with negative charge having positive charge, which remain on the surface after the transfer as the first brush makes contact with the surface.

BRIEF DESCRIPTION OF THE DRAWINGS Other features of the present invention will become apparent as the following description proceeds and with reference to the drawings, in which: Figure 1 is a schematic illustration of the prior art; Figure 2 is a schematic illustration of another embodiment of the present invention; Figure 3 is a schematic illustration of one embodiment of the present invention using a single positively polarized brush; and Figure 4 is a schematic illustration of a printing apparatus incorporating the inventive features of the present invention. Although the present invention will be described in relation to its preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of a color electrostatic printing or copying machine, in which the present invention may be incorporated, reference is made to U.S. Patents 4,599,285 and 4,679,929, the contents of which are incorporated herein by reference, which describes the image in the process of forming the image that has revealed multiple steps with a single pass of transfer. Although the cleaning method and apparatus of the present invention is particularly well suited for use in a color electrostatic printing or copying machine, it should become apparent from the following discussion, which is equally well suited for use in a wide variety of applications. devices and is not necessarily limited to the particular embodiments shown herein. Now with reference to the drawings, where the drawings are for the purpose of describing a preferred embodiment of the invention and not to limit it, the various processing stations employed in the reproduction machine illustrated in Figure 14 will be briefly described. A reproduction machine, of which the present invention finds advantageous use, utilizes a load retaining member in the form of the photoconductive strip 10 consisting of a photoconductive surface and a light transmitting, electrically conductive substrate mounted for movement to pass through. the charging station A, and the exposure station B, the developer stations C, the transfer station D, the fusion station E and the cleaning station F. The band 10 moves in the direction of the arrow 16 to advance its successive portions sequentially through the various processing stations placed around the path of its movement. The band 10 is trapped around a plurality of rollers 18, 20 and 22, the first of which can be used to provide adequate tensioning of the photoreceptor band 10. The motor 23 rotates the roller 18 to advance the band 10 in the direction of arrow 16. Roller 20 is connected to motor 23 by suitable means such as a belt driver. As can be seen by further reference to Figure 14, the initially successive portions of the band 10 pass through the charging station A. At the charging station A, a corona device such as a scorotron, corotron or dicorotron indicated generally by the reference number 24, it charges the band 10 to a selectively very uniform positive or negative potential. Any suitable control, well known in the art, can be used to control the corona device 24. Next, the charged portions of the surface of the photoreceptor are advanced through the exposure station B. In the exposure station B, the uniformly charged photoreceptor or the charge retaining surface 10 is exposed to a laser based on an input scanning device 25 and / or departure, which causes the retainer surface of the load to be discharged according to the output of the scanning device (eg, a Two-Tier Trace Exit Scanner (ROS)). The photoreceptor, which is initially charged to a voltage, undergoes dark decrease at a voltage level. When exposed to exposure station B, it is discharged to near zero or ground potential for the image forming area in all colors. In the developing station C, a developing system, indicated generally by the reference number 30, advances the developing materials in contact with the electrostatic latent images. The development system 30 comprises the apparatuses first 42, second 40, third 34 and fourth 32 of developer. (However, this number may increase or decrease depending on the number of colors, ie four colors are mentioned here, so there are four revealing accommodations). The first developer apparatus 42 comprises a housing comprising a housing containing a donor roller 47, a magnetic roller 48 and a developer material 46. The second developer apparatus 40 comprises a housing containing a donor roller 43, a magnetic roller 44 and a developer material. The third developing apparatus 34 comprises a housing containing a donor roller 37, a magnetic roller 38 and a developer material 39. The fourth developer apparatus 32 comprises a housing containing a donor roller 35, a magnetic roller 36 and the developer material 33. The magnetic rollers 36, 38, 44 and 48 reveal the organic pigment in the donor rollers 35, 37, 43 and 47 respectively. The donor rollers 35, 37, 43 and 47 then reveal the organic pigment on the image forming surface 11. It is noted that the developing housings 32, 34, 40, 42 and any of the subsequent development elements must be less sequestering or debugging in order not to interrupt the image formed by the pre-development apparatus. All 4 accommodations contain developer material 33, 39, 45, 46 of selected colors. The electrical polarization is carried out by means of the power supply 41, electrically connected to the developer devices 32, 34, 40 and 42.

The sheets of substrate or support material 58 are advanced to transfer D from the supply tray, not shown. The sheets are fed from the tray by a sheet feeder, also not shown and fed to transfer D through a corona loading device 60. After the transfer, the sheet continues to move in the direction of arrow 62 to the fusion station E. The fusion station E includes a fuser assembly, indicated generally by reference number 64, which permanently fixes the powder images. of organic pigment transferred to the leaves. Preferably, the fuser assembly 64 includes a heated fuser roller 66 adapted to be press-fitted with a back-up roll 68 with the images of organic pigment powder in contact with the fuser roller 66. In this form, the organic pigment powder image is permanently fixed to the sheet. After fusion, the copy sheets are directed to a holding tray, not shown or finishing station for joining, stapling, aligning, etc. and removal of the machine by the operator. Alternatively, the sheet can be advanced to a duplex tray (not shown) from which it will be returned to the processor to receive a second side copy. At the leading edge to the trailing edge the inversion and a non-leaf reversal number is generally required for the presentation of the second side for copying, however, if the information is placed in the form of additional information or second color information, it is advantageous on the first side of the sheet, and no leading edge is required to the reverse back edge. Of course, the return of the sheets for duplex or override copying can also be done manually. The residual organic pigment and debris remaining in the photoreceptor band 10 after each copy is made can be removed at cleaning stations F with a brush or other type of cleaning system 70, after the particles are charged by the cleaner. corotrón 96 of pre-cleaning. The cleaning system is supported under the photoreceptor band by two supports 160 and 170. Reference is now made to Figure 1, which shows the polarization polarity of the conventional brush for a DESB cleaning (ie double electrostatic brush) to eliminate residual negative triboelectric organic pigment particles from an image forming surface. A negative pre-cleaning corotron 96 provides negative charge to the residual negative triboelectric organic pigment particles 95 remaining on the photoreceptor 10 (e.g., the image forming surface) after transfer. Sample G of residual organic pigment particles predominantly carries a high negative charge after pre-cleaning (although a small amount of low positive charge is present). Negative triboelectric organic pigment particles accept negative charge from negative pre-cleaning. This is an inherent characteristic of the organic pigment which allows the negative triboelectric organic pigment particles to have a high negative charge value in the organic pigment sample G. Thus, the first cleaning brush 100, in the direction of movement (shown by the arrow 16) of the photoreceptor 10, is positively polarized to attract the G particles of organic pigment charged predominantly in negative form of the photoreceptor 10. The first brush 100 positively polarized removes a substantial portion of the sample G of organic pigment which is finally organic pigment separated from the brush 100. However, a small portion of the sample G is frequently not cleaned by the first brush 100, (ie, a small portion passes under the brush 100 and a small amount can be deposited from the brush 100 on the photoreceptor 10) and remains on the photoreceptor 10, after the first light 100 is a sample of organic pigment H. The residual H sample of the triboelectric organic pigment 95 is positively charged predominantly after contact with the positively polarized brush 100.

Continuing with reference to Figure 1, the second brush 105, in the direction of movement (shown by arrow 16) of the photoreceptor 10, is negatively polarized. Some of the sample H is removed by the second brush 105 due to the positive charge on the negative triboelectric particles. However, sample I of residual organic pigment remains after the second cleaning brush 105, due to the inherent negativity of the triboelectric particles, which accept the negative charge of the negatively polarized brush. This creates highly charged negative particles, which the second negative polarization brush can not clean. Therefore, this conventional cleaning system does not clean the image forming surface of residual particles that are triboelectrically negative. The present invention provides for the efficient cleaning of triboelectrically negative organic pigment particles, which are being used with increasing frequency in printer and copier applications. Reference is now made to Figure 2, which shows the preferred embodiment of the present invention, using electrostatic, double cleaning brushes. Sample K of residual organic pigment of negative, triboelectric organic pigment particles 95 is negatively charged by negative pre-cleaning 96. The first brush 100, in the direction of movement, shown by arrow 16 of photoreceptor 10, is deflected positively to remove the negatively charged residual sample K from the photoreceptor 10. The sample K of organic pigment is separated from the brush 100 by an organic pimento separation roller 101. (Other means for removing the organic pigment not shown, include the separation of organic pigment with air and rods). The organic pigment particles not removed by the first positively polarized cleaning brush 100, on the photoreceptor 10, are shown by the sample L of organic pigment. The first positively polarized brush 100 cleans the particles of negative triboelectric organic pigment 95, positively charged in the organic pigment sample L. The second brush 106 in the direction of movement of the photoreceptor 10, shown by the arrow 16, is also positively polarized . The second brush 106 positively polarized removes the sample L of organic pigment from the photoreceptor 10. The sample L of organic pigment is then removed from the second brush 106 by an organic pigment removing roller 107. The sample L of positively charged organic pigment is removed from the photoreceptor 10 by the second brush 106 positively charged, due to the following reasons: 1) the organic pigment particles 95 are triboelectrically negative and the positive brush has an affinity for the organic pigment, even when the particles have some positive charge; and 2) sufficient brush strokes of the brush are sufficient to remove the organic pigment from the photoreceptor. For example, it has been shown through experimentation, that a single brush with 18 fiber strokes, cleans the residual organic pigment from the receiver, after the transfer in a printer or copier. In this way with two brushes, each brush needs only to have nine strokes of fiber to clean the organic pigment of the photoreceptor. The mass density of the organic pigment of the residual particles that in the second brush is required to clean is very light, while the mass of this organic pigment can not be measured, the particles can be counted. Typically, the number of particles in sample L is in the range of 100 to 1000 particles per mm2. The second brush 106 easily cleans this density of light organic pigment. These particles have to be cleaned because the requirement for the cleaner is less than 30 particles per mm2. In the present invention, the + / + polarization (that is, positive, positive) of the double brush cleaner avoids the cleaning faults associated with the charge injection phenomenon (polarized cleaners +/-). The present invention is based on the affinity that the triboelectric organic pigments have positively polarized conductive brushes and also in providing sufficient fiber strokes for the second brush to clean the sample L of residual organic pigment. In the present invention, it was determined experimentally that the correct polarity of the brush for the neutral triboelectric pigment 95 and a corotron 96 of negative pre-cleaning, for a double ESB (ie electrostatic brush) or the conductive cleaner, is + / +, that is, both brushes are positively polarized. The reason that the correct polarity for using a double cleaning system is + / + (ie, both positively polarized) is due to a +/- cleaning system (ie, the first cleaner, in the direction of movement, is positively polarized and the second cleaner in the direction of movement, is negatively polarized) will not clean when the first positive cleaner does not clean all of the organic pigment from photoreceptor 10. (See Figure 1). Referring again to Figure 1, the reason that a second brush 125 negatively polarized does not clean the organic pigment particles 95 that are not removed by the first positive brush 100, is due to the phenomenon of charge injection (the injection phenomenon). of charge is explained in the application No. co-pending (not yet assigned) - File of Attorney No. D / 96038Q), deposited together with the present, the description of which is fully incorporated herein for reference). The brush 105 negatively polarized, injects or transfers negative charge to the negative triboelectric organic pigment. To establish this in another way, due to charge injection, a negatively polarized brush 100 injects negative charge into the triboelectric, negative pigment 95 and a positively polarized brush 100 does not inject charge into the triboelectric, negative pigment 95. In this way, any negative triboelectric organic pigment 95, which reaches the second brush 105 negatively polarized is charged more negative (see sample I) and is repelled instead of being attracted (ie cleaned by) brush 105 negatively polarized. However, a positively polarized brush can clean positively charged triboelectric organic pigment. Laboratory experimentation showed that brushes 100, 106, positive, double cleaners as shown in Figure 2, clean the organic pigment loads in the Q / D range of approximately -1.7 to +0.45 fc / micron (where Q is the charge of the particle, D is the diameter of a particle and the height of a distribution represents the number of particles that have a charge Q / D), and, additionally, after the transfer, the organic pigment Q / D positive does not exceed approximately +0.5 fc / micron. The reason that positive QD values greater than 0.5 fc / micron are not found is due to the fact that the negative organic pigment does not readily accept positive charge. The negative triboelectric organic pigment prefers to remain negative or to become even more negative. Therefore, the positive charge in the negative triboelectric organic pigment does not have a high positive value and the cleaning of this organic pigment is feasible with a positive brush with sufficient fiber strokes. In addition, note that after pre-cleaning, the charge distribution of the transfer organic pigment is displaced more negatively, making the organic pigment charge more ideal for attracting positive, double-charged cleaning brushes (ie +, + ). After the pre-cleaning treatment, the positive Q / D value is approximately 0.2 fc / micron (for comparison, a high negative charge value, after a negative pre-cleaning, has a Q / D of approximately -1.5 fc / micra). Reference is now made to Figure 3, which shows an alternate embodiment of the present invention, using a single positively polarized cleaning brush. A single brush 100 positively biased, instead of double ESB, can be used to clean the triboelectric, negative pigment particles 95 shown in sample J, which remain on the surface of photoreceptor 10 after transfer. However, it takes more than 8 strokes of brush fiber to clean the photoreceptor 10. Approximately 18 strokes of fiber are required with a single brush 100 positively polarized to clean efficiently. In a double brush cleaning system as shown in Figure 2, only about 9 fiber strokes per brush are required. The blows of the fibers are proportional to the brush's rpm and the brush's wave density. These parameters are selected from. according to the cleaning application. The use of a single brush 100 positively polarized, in this way, also eliminates the complicated cam mechanisms, normally required for double brush cleaners in multi-pass color printing operations. Continuing with reference to Figure 3, the sample of organic pigment particles J are negatively charged by the negatively polarized pre-cleaning corotron 96. The cleaning brush 100 positively polarized, efficiently clean sample J of organic pigment from the surface, because the brush rotates at 100 rpm or the wave density is increased in such a way that the number of fiber strokes for a single brush is approximately equal to the strokes of the fiber for the double brush cleaner. A roller 101 for removing organic pigment (or other device for removing organic pigments) removes the organic pigment from the sample J of the brush 100. Probed or directed towards a waste container (not shown). In recapitulation, the present invention in the preferred embodiment of the double brush cleaner uses several inherent properties of the negative triboelectric organic pigments. First, the negative triboelectric organic pigment has a strong affinity for accepting negative charge. In this way, the residual organic pigment after the transfer is negatively charged with a negative pre-cleaning corotron, this creates a negative organic pigment charge distribution that is essentially all negative and makes the cleaning efficiency of the first brush almost 100% Second, the negative triboelectric organic pigment does not accept positive charge. In this way, the Q / D value for the positive organic pigment is low. Since the cleaning efficiency of the first brush is high and the mass density of the organic pigment after the first brush is low, the Q / D for this organic pigment is low. Therefore, the fiber strokes required for the second brush are selected to clean this organic pigment after the first brush.

Usually, about nine strokes of fibers are sufficient to clean the residual organic pigment after the first brush. Finally, the negative triboelectric organic pigment, even though this organic pigment can be positively charged, has an affinity for the positive brush. Hence, in the alternative embodiment of this invention (i.e. the individual positive brush cleaner), effective cleaning is obtained by providing sufficient strokes of fiber for cleaning. Approximately 18 fiber strokes are required to clean the bulk densities of typical organic pigment after transfer with a single positive brush. Therefore, it is apparent that the positive polarization of dual electrostatic brushes with a negative pre-cleaning corotron for negatively charged triboelectric organic pigment, which fully satisfies the purposes and advantages established hitherto, has been provided in accordance with the present invention. Although this invention has been described in conjunction with its specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. Having described the invention as above, the following are claimed as property:

Claims (16)

CLAIMS;

1. An apparatus for removing triboelectric particles with negative charge from a surface, the surface is capable of movement, characterized in that it comprises: a pre-cleaning corotron having a first polarity; and a first cleaning means for triboelectric particles with a negative charge on the surface having a second polarity different from the first polarity of the pre-cleaning corotron.

2. The apparatus according to claim 1, characterized in that the first cleaning means comprises a first brush.

3. The apparatus according to claim 2, characterized in that the first brush is conductive.

4. The apparatus according to claim 3, characterized in that the first polarization comprises a negative charge.

5. The apparatus according to claim 4, characterized in that the first brush comprises a rotational speed that allows about 18 strokes of fiber to remove the particles from the surface.

6. The apparatus according to claim 4, further characterized in that it comprises: a second means for cleaning the triboelectric particles with negative charge, from the surface having the second polarization, the second cleaning means is located downstream of the first cleaning means , in the direction of the movement of the surface; and a housing, the first cleaning means and the second cleaning means are partially contained therein.

7. The apparatus in accordance with the claim 6, characterized in that the second cleaning means comprises a second brush.

8. The apparatus in accordance with the claim 7, characterized by the second brush is conductive.

9. The apparatus in accordance with the claim 8, characterized in that the second polarization comprises a positive charge.

10. The apparatus in accordance with the claim 9, characterized in that the first brush and the second brush, both are positively polarized, in contact with the surface, to remove the particles from it.

11. The apparatus in accordance with the claim 10, characterized in that the first brush is positively charged, eliminates the triboelectric particles with negative charge, which have predominantly negative charge of the surface.

12. The apparatus in accordance with the claim 11, characterized in that the second brush is positively charged, eliminates the triboelectric particles with negative charge, which have predominantly positive charge of the surface.

13. The apparatus in accordance with the claim 12, characterized in that the first brush comprises a first rotational speed that allows about 9 strokes of fibers to remove the particles from the surface.

14. The apparatus according to claim 13, characterized in that the second brush comprises a second rotational speed that allows approximately 9 strokes of fibers to remove the particles from the surface.

15. A method for cleaning triboelectric particles with positive charge from a movement surface, characterized in that it comprises: transferring an image to a printing medium; pre-clean the particles that remain after the transfer, on the surface, using a negatively charged corotron; load a first brush positively to remove both of the negatively charged triboelectric particles, which have a negative charge, and the negatively charged triboelectric particles, which have a positive charge that remain on the surface after the transfer, as the first brush makes contact with the surface.

16. The method according to claim 15, further characterized in that it comprises: the step of loading a second brush positively located downstream of the first brush in a direction of movement of the surface, to remove both of the triboelectric particles with negative charge, which they have negative charge and triboelectric particles with negative charge, which have a positive charge that remain on the surface, after the transfer as the second brush makes contact with the surface.