Patent Publication Number: US-11378898-B2

Title: Magnetic carrier bead separation

Description:
BACKGROUND 
     A dual-component printer makes use of toner and carrier beads in electrophotographic printing systems. Toner particles are held to carrier beads through primarily electrostatic forces. Carrier beads tend to form chainlike bristles in the presence of magnetic fields. The carrier beads and any formed carrier bead chains can temporarily attach to a roller due to transporting magnets located within the roller. The roller may rotate in order to apply the carrier beads and toner against organic photo conductor before the carrier beads may be released for return to a developer sump. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Certain examples are described in the following detailed description and in reference to the drawings, in which: 
         FIG. 1A  is a block diagram of an example dual-component printing device that separates carrier beads with a magnetic separator by magnetic properties gained over the time-of-use of the carrier beads; 
         FIG. 1B  is a block diagram of another example dual-component printing device that separates carrier beads with a magnetic separator by magnetic properties gained over the time-of-use of the carrier beads; 
         FIG. 2  is a block diagram of an example dual-component printing device that separates carrier beads with a magnetic separator auger; 
         FIG. 3  is a block diagram of an example dual-component printing device that separates carrier beads with a magnetic separation and agitation auger; 
         FIG. 4  is a block diagram of an example dual-component printing system that separates carrier beads with a magnetic separator located between the release point of a roller and the developer sump; and 
         FIG. 5  is a flowchart of an example method for separating carrier beads by magnetic properties gained over time-of-use. 
     
    
    
     DETAILED DESCRIPTION 
     This present disclosure relates to a method, device, and system in dual-component printing that separates carrier beads with a magnetic separator by utilizing the magnetic properties that carrier beads gain over their time-of-use. As used herein, the term magnetic refers to items which are affected by magnetic fields. The term magnetic does not necessarily imply that permanent or semi-permanent magnetic fields are formed by an item described as magnetic. While a magnetic item may include items that produce magnetic fields, the use of the phrase ‘magnetic items’ in this disclosure also includes items that can be attracted to magnets or items to which magnets are attracted. In an example, an item made of iron would be considered magnetic even when it is not generating a magnetic field as the item of iron would attract magnets or other items acting as magnets. The magnetic separator referred to in this disclosure includes items made of materials that attract magnetized items. Magnetized items are items that produce magnetic fields. In an example, magnetized items are items exhibiting qualities of magnets and can include permanent magnets, induced magnets, and other items caused to take on the properties of magnets. In an example, a piece of iron may become magnetized through repeated rubbing of a magnet against the iron in order to align the magnetic domains of the iron to produce a larger field of magnetic effects coming from the now magnetized iron. 
       FIG. 1A  is a block diagram of an example  100  dual-component printing device that separates carrier beads with a magnetic separator by magnetic properties gained over the time-of-use of the carrier beads. The dual-component printing device  102  operates through use of the two components, carrier and toner. As used herein, carrier refers generally to the large number of microscopic carrier beads that are one of the two-components in the dual component printing device  102 . As used herein, toner refers generally to the large number of toner particles that attach to carrier beads as a result of electrostatic forces. In an example, carrier beads can be polymer coated and may also be magnetic. Carrier beads may be attracted to magnets or magnetic fields. In the presence of magnetic fields, carrier beads may form bristle like chains with one another. The toner may stay attached to the carrier bead until rubbed, applied, or attracted to the surface of organic photo conductor (OPC) or other non-organic photo conductive materials. Throughout this application, reference to OPC can also include other non-organic photo conductive materials, however OPC may be referenced for ease of reference. The carrier beads, collectively referred to as carrier, and the toner particles, collectively referred to as toner, may be stored or held in a developer sump  104 . The developer sump  104  may be a bin that has input holes, valves, or ports so that additional carrier and toner may be added. The developer sump  104  may be a tangible container including walls and the holding space enclosed or partially enclosed by walls. Carrier (including a plurality of carrier beads  108 ) and toner  124  inside the developer sump  104  may be pulled out by magnets held inside a roller  106 . In an example, the roller  106  may be a naturally non-magnetic material such as aluminum. The plurality of carrier beads  108  that make up the carrier may be stored in the developer sump  104 . The carrier may attach to the roller  106  at an attachment point  110 . The roller  106  may rotate in place so that the carrier beads are rotated to brush against an OPC where the toner transfers to the OPC while the carrier beads remain attracted to magnets located under the roller  106 . At the release point  112  located on the path of the roller  106 , the carrier beads are released as magnets are not located underneath the release point  112  of the roller. After carrier has been released at the release point, the released carrier beads (which are used carrier beads  126 ) and remaining toner returns to the developer sump  104 . The plurality of carrier beads  108  located in the developer sump  104  includes both unused carrier beads and used carrier beads that were applied to the OPC through the motion of the roller  106  moving the carrier and locating the carrier and toner adjacent to the OPC. The point of application may be referred to as an attachment point. In an alternative example, rather than wait for the carrier or toner to detach at a release point, a magnetic separator (shown as  120  in  FIG. 1B ) may be located after the application point and before the release point  112  in contrast to machines that allow magnetized carrier beads to return towards the development sump  104 . 
     Over time and through repeated use, carrier beads can become magnetized. In an example, the repeated and durational exposure of the carrier beads to the magnets located inside the roller  106 , can result in magnetized carrier beads. The effects of this magnetization on the carrier beads increase the strength of carrier bead magnetization over time and the frequency of carrier bead use. Accordingly, the older and more frequently a carrier bead is used, the more it becomes magnetized. Older, more frequently used carrier beads may exhibit properties of induced magnets. Using this induced magnet property is useful in separating older carrier beads from fresher carrier beads. As older carrier beads may have toner impacted on their surface, these carrier beads may be poorer in their function of carrying toner to the OPC along the path of the roller  106 . Accordingly, separation of older carrier beads enables disposal and replacement of these older beads rather than disposal of both old and fresh carrier beads. 
     One technique for separating out older carrier beads disclosed herein is through the use of a magnetic separator  114  (or  120 ). As discussed and distinguished above, the magnetic separator may or may not be magnetized. The term magnetic in magnetic separator refers to a property that the separator possesses, that it interacts with magnetic fields. In an example, this can mean that the magnetic separator  114  is attracted to magnetized items. Likewise, magnetized items, such as a magnetized carrier bead may be attracted to the magnetic separator  114 . 
     In an example, the magnetic separator  114  may take the form of an inverted ramp located above the development sump  104  that is holding the plurality of carrier beads  108 . The magnetic separator  114  is located in propinquity to the development sump  104  such that a magnetized carrier bead is attracted to the magnetic separator  114  such that it leaves the mixture of the plurality of carrier beads  108  in order to attach to the magnetic separator  114 . 
     The magnetic separator  114  may be made of iron, nickel, cobalt, a magnetic alloy, and other magnetic materials. In an example the magnetic separator may be not be magnetized, but instead merely a material to which magnetized items are attracted. The magnetic separator  114  can include a ramp which is stationary that magnetized carrier beads slide along until they reach an end for removal into a waste area by either a removal mechanism or by falling due to gravity and reduced strength of their own magnetizing or forced distance from the magnetic material of the magnetic separator. In an example, the magnetic separator can include a moving surface such that once the magnetized carrier beads are attached, they are moved by the movement of the magnetic separator away from the developer sump  104 . The magnetic separator  114  may include a moving flexible belt or a moving series of rigid panels arrange to approximate a flexible belt. The magnetic separator  114  may be completely magnetic or may be partially magnetic in that portions of the magnetic separator  114  may be magnetic while others are non-magnetic. In an example, the magnetic separator  114  may have magnetic metal underneath a non-magnetic covering. This covered magnetic metal may include a belt made of magnetic metal that is rubberized such that non-magnetic rubber is covering the surface of the magnetic separator  114 . In an example, another non-magnetic material other than rubber may be used. This non-magnetic covering may function similarly to the roller  106  in that it moves the magnetized carrier beads to a position where the magnetic material is no longer present and the carrier beads may be released from the magnetic separator into a bead waste  122  ( FIG. 1A ). 
     The magnetic separator  114  may be inverted at a variety of angles. In an example, the magnetic separator  114  may be located such that it is approximately parallel to a fill line of settled carrier. In an example, the magnetic separator  114  may be angled so that it is a ramp and not an inverted ramp. In each of these examples, the magnetic separator may be moving or stationary to correspond to the sufficient attachment of magnetized carrier beads. 
     As discussed above, as carrier beads are used and repeatedly cycled through the roller  106  and developer sump  104 , they become magnetized. Thus, by using a magnetic separator  114 , the magnetized, older carrier beads are separated from fresher carrier beads. This can improve the function of the machine because over time, carrier beads can become impacted with toner particles which are stuck to the carrier beads not by electrostatic forces but through compressive and friction forces. Carrier beads with impacted toner particles are less able to triboelectrically charge the toner particles or to carry toner particles while on the roller  106  and can be less able to attach to the roller at all. Rather than having to dump out a mixture of old less usable carrier beads and fresher less used carrier beads, the use of a magnetic separator  114  enables more efficient removal of older carrier beads. Through more efficient separation techniques, replacement of fresher carrier is less frequent with fewer carrier beads used overall. This reduction in replacement frequency reduces the number of times a person has to service the printing machine. Further, the reduced use of carrier beads results in a cost savings from reduced demand for fresh carrier beads to be input. 
       FIG. 2  is a block diagram of an example dual-component printing device  102  that separates carrier beads with a magnetic separator auger  200 . Like numbered items are as described with respect to  FIG. 1A . 
     The older carrier beads may be separated by a magnetic separator auger  202 . As the beads collect in the developer sump  104 , attachment of toner and an appropriate ratio of toner to carrier involves mixing and agitating the collection of toner and carrier in the development sump  104 . The use of at least one agitation auger  204  may be used in the development sump  104  in order to appropriately mix the toner and carrier. In an example, as fresh toner and carrier is added, the agitation auger  204  ensures an appropriate mix and composition of the fresh and old carrier and toner. The term auger can refer to an elongated screw shaped component that rotates in order to mix the carrier and toner. In an example, the auger may be approximately screw shaped such that a spiraling protrusion wraps around the lengthwise side of the auger (e.g., the magnetic separator auger  202  is approximately screw shaped such that a spiraling protrusion wraps around the length  220  of the magnetic separator auger  202 ). In an example, other variation of auger shapes can be used including non-continuous spiral wrapping, protrusions at random intervals, or other non-rotationally symmetrical shapes capable of mixing components while the auger is active. 
     The dual-component printing device  102  may include a number of agitation augers like the agitation auger  204  spaced at various intervals in the developer sump  104 . In an example, the agitation auger  204  may be made of non-magnetic material. The magnetic separator auger  202  is made of magnetic material. As the magnetic separator auger  202  may be located in the development sump  104 , it may be partially or completely submerged under carrier, toner, or a mix of both. As the magnetic separator auger  202  is magnetic, older carrier beads may be attracted to the magnetic separator auger  202 . As the magnetic separator auger  202  may additionally have a screw shape that may rotate around the lengthwise axis. This rotational movement can move carrier beads that have been attracted to the magnetic separation auger  202  towards an end of the magnetic separation auger  202  based on the direction of the spiraling and the direction of rotation of the magnetic separation auger  202  and in some cases the agitation auger  204 . 
     In an example, the magnetic separation auger  202  may extend outside of the developer sump  104  and attached carrier beads may be brushed off through physical means at the end of the magnetic separation auger  202 . In an example, the magnetic separation auger  202  may have portions that are non-magnetic, in some cases the non-magnetic portions of the magnetic separation auger  202  may be at the ends. With these non-magnetic portions located at the end, the attached carrier beads may detach once they have reached the end of the magnetic separation auger  202 . A separation point along the end of the magnetic separation auger  202  may be aligned with a bead waste. The bead waste may be a holding location or disposal mechanism for older carrier beads to be stored until they can be manually retrieved. 
     While the magnetic separation auger  202  may also move non-magnetized carrier beads, these beads will not be attracted to the magnetic separation auger  202  and as such, are unlikely to travel the full length of the magnetic separation auger  202 . In an example, the magnetic separation auger  202  may be angled to travel upwards in order to further aid in separation between magnetized and non-magnetized carrier beads. Similarly to an inverted ramp, a magnetic separation auger  202  angled to travel upwards may push magnetized carrier beads upwards while fresher, non-magnetized carrier beads can fall back towards the developer sump  104 . 
       FIG. 3  is a block diagram  300  of an example dual-component printing device  102  that separates carrier beads with a magnetic separation and agitation auger  302 . Like numbered items are as described with respect to  FIG. 1A . 
     The magnetic separation and agitation auger  302  may combine the roles of a magnetic separator with that of the agitation auger. In an example, there may be a single auger that both serves to agitate the mixture of carrier and toner as well as separate out magnetized carrier. 
     In an example, the magnetic separation and agitation auger  302  can be the sole auger in the developer sump  104 . The magnetic separation and agitation auger  302  may be partially or completely below a target fill line for a carrier bead and toner particle mixture in the developer sump  104 . 
     The term magnetic separation and agitation auger  302  refers to a screw shaped auger system that can attract magnetized carrier beads due to the materials that make up the magnetic separation and agitation auger  302 . The agitation is primarily to ensure an appropriate mixture and triboelectric charging of the toner and carrier in the developer sump  104 . In an example, the magnetic separation and agitation auger  302  can take a number of auger-like shapes that shunt, funnel, or otherwise push magnetized carrier beads away from the developer sump  104 . 
     In an example, other shapes other than an auger could be used as a magnetic separator within the developer sump  104 . This includes the number of variations as described above with respect to the magnetic separator  114 . Further, a magnetic separator within the developer sump could include a separator arm that has a magnetic end that is retractably placed into the developer sump  104 . The magnetic separator in a retractable arm shape could be used to both mix and separate old carrier beads from fresher carrier beads by attracting the older magnetized carrier beads as the arm moved through, into, and out of the developer sump  104 . In an example, a magnetic separator in a retractable arm shape could be a single shaft rod, a multi-prong mixer, a sphere, a plurality of spheres, a rectangular prism, or any other shape or plurality of shapes smaller than the developer sump  104 . In an example, a retractable arm could make use of a separate wiping element to remove magnetized carrier beads that are gripping the magnetic separator. In an example, a wiping element could be located separately near a bead waste so that as the carrier beads are wiped from the magnetic separator they fall or are guided towards the bead waste. In another possible example, the magnetic arm itself could resemble the roller  106  in that an outer non-magnetic casing could surround an inner core could be magnetic on one portion of the magnetic arm and not magnetic on the remaining portions. In this example, the non-magnetic casing could rotate around the partially magnetic inner core to move attracted carrier beads to a side of the magnetic separator they would no longer be attached. In this example, the magnetic separator arm could be inserted into the developer sump  0104  where magnetized carrier beads could attach. The magnetic separator arm could then be removed from the developer sump or at least above the mixture of carrier beads and toner so that non-magnetized carrier beads and toner could fall back into the developer sump  104 . The magnetic separator arm could then be moved towards a bead waste or bead waste path where the non-magnetic outer casing could rotate so that magnetized carrier beads would no longer be near the magnetic inner core and could fall into the bead waste. 
       FIG. 4  is a block diagram of an example dual-component printing system  400  that separates carrier beads with a magnetic separator located between the release point of a roller and the developer sump. Like numbered items are as described with respect to  FIG. 1 . 
     As part of the dual-component printing system  400 , a roller  106  in a developer unit  402  draws carrier beads from the developer sump  104  and can provide the toner to organic photographic carrier (OPC). The carrier beads on roller  106  are brought into contact (at an application point  422 ) with a rotating OPC drum  404  located in a drum unit  406  that applies the toner to the print medium in the dual-component printing system  400 . In an example, as the roller of the developer  106  has provided the toner to the OPC, the carrier beads and some toner may return toward the development sump  104 . At a release point from the roller  106 , the carrier beads may be released. Of these released carrier beads, some may be magnetized through their repeated use on the roller  106 . In an example, the magnets of the roller  106  may induce the carrier beads to become magnetized over time. 
     A magnetic separator  408  may be located between a release point and the developer sump  104 . As discussed above, as carrier beads age and are used more frequently, they become magnetized. As they are released from the release point of the roller  106 , any magnetized carrier beads would attach to the magnetic separator  408  located between the release point of the roller  106  and the developer sump. This magnetic separator  408  could be structurally similar to the magnetic separator of  FIG. 1A , and the magnetic augers  202  and  302 . The location of the magnetic separator  408  between the release point of the roller  106  and the development sump  104  could allow increase ease of movement of the magnetic separator  106  as it turns, retracts, or advances carrier beads towards a bead waste. 
     In an example, the magnetic separator  408  can be located in a free fall area for the carrier beads located between the release point of the roller  106  and the developer sump  104 . In an example, the magnetic separator  408  could be located along a guided track, path, or moving belt that guides carrier beads towards a bead waste and away from the developer sump  104 . 
     The dual-component printing system  400  may also include a carrier bead input port  420 . The carrier bead input port  420  may be the same opening in the device as a toner input. As discussed above, old carrier beads that may have lost their efficacy due to impacted toner that blocks ability of carrier bead to effectively triboelectrically charge the attached toner and for toner to be removably attached to the carrier beads. Previously no means for separating these older carrier beads was possible and older, ineffective carrier beads were removed along with mixed in functional carrier beads and unused toner, resulting in wasted carrier and toner. By being able to selectively remove older, more magnetized beads, there is less ancillary disposal of still functional carrier beads, and thus less waste, and less need for refilling the carrier beads and toner. 
     In an example, the composition or mixture of carrier beads and toner can be measured on an ongoing basis so that as older carrier beads are filtered out or toner is used, the levels and mixture ratios can signal for additional carrier beads or toner to be added. In an example, a specific amount of carrier beads or toner may be added in a corresponding amount to how many carrier beads or toner has been removed from the developer sump. In an example, the amount of carrier beads or toner to add may correspond to a measurement made of the ratio of toner and carrier beads in the developer sump. In an example, the amount of carrier beads or toner to add may correspond to a measurement made of how full the development sump is along with the ratio of toner and carrier beads in the developer sump. For carrier beads, the amount of carrier beads to add may correspond to a measurement made of the how many magnetized carrier beads are removed from the developer sump or removed to the bead waste. These measurements may be made electronically, conductively, digitally, through weight or volume measurements, or other suitable measuring sensor mechanisms. 
       FIG. 5  is a flowchart of an example method  500  for separating carrier beads by magnetic properties gained over time-of-use. At block  502 , a developer sump of a dual-component printing device stores a plurality of carrier beads. At block  504 , a roller moves a subset of the plurality of carrier beads from an attachment point on the roller to a release point through the rotation of the roller, wherein the subset of the plurality of carrier beads return towards the developer sump after they are released at the release point. 
     At block  506 , a magnetic separator separates a magnetized carrier bead from the plurality of carrier beads with a magnetic separator located between the release point and the attachment point to guide the magnetized bead away from the developer sump and the roller. In an example, the magnetic separator is an inverted magnetic ramp located above the developer sump relative to the ground or a surface the dual-component printing device is resting upon such that the magnetized carrier bead of the plurality of carrier beads is attracted to the inverted magnetic ramp that guides attracted carrier beads away from the developer sump and towards a bead waste. The magnetic separator may also be a moving magnetic separator to attract the magnetized carrier beads between the release point and the attachment point. In an example, the magnetic separator is located above the developer sump relative to the ground or a surface the dual-component printing device is resting upon. The magnetic separator may also be located to pass through the developer sump. In an example, the magnetic separator is located between the release point and the developer sump. The magnetic separator may also be a magnetic auger located in the developer sump that spins around the longest or longer dimension of the magnetic auger, the magnetic auger to attract the magnetized carrier bead of the plurality of carrier beads and move the carrier bead towards a bead waste. In this example, the magnetic separator may instead be a mixing auger in the developer sump. As far as location, the magnetic separator can be located between the release point and the developer sump. 
     The method  500  may further include delivering magnetized carrier beads to a bead waste where the dual-component printing device includes a fresh carrier bead input port (e.g.,  420  in  FIG. 4 ). In this example, the fresh carrier bead input port opens to allow fresh carrier beads to enter the developer sump in response to a detected amount of the plurality of carrier beads moved to the bead waste as a result of the magnetic separator. 
     While the present techniques may be susceptible to various modifications and alternative forms, the techniques discussed above have been shown by way of example. It is to be understood that the technique is not intended to be limited to the particular examples disclosed herein. Indeed, the present techniques include all alternatives, modifications, and equivalents falling within the scope of the following claims.