Patent Application
20210325797
A printer may apply print agents to a paper or another print substrate. One example of a printer is a liquid electro-photographic (“LEP”) printer, which may be used to print using a fluid print agent such as an electrostatic printing fluid. Such electrostatic printing fluid includes electrostatically charged or chargeable particles (for example, resin or toner particles which may be colorant particles) dispersed or suspended in a carrier fluid).
In an example of LEP printing, a printing device may form an image on a print substrate by placing an electrostatic charge on a photo imaging plate (“PIP”), and then utilizing a laser scanning unit to apply an electrostatic pattern of the desired image on the PIP to selectively discharge the PIP. The selective discharging forms a latent electrostatic image on the PIP. The printing device includes a developer system (sometimes referred to as a “developer unit” or a “BID”) to develop the latent image into a visible image by applying a thin layer of electrostatic print agent (which may be generally referred to as “LEP print agent”, “electronic print agent” or “electronic ink” in some examples) to the patterned PIP. Charged toner particles in the LEP print agent adhere to the electrostatic pattern on the PIP to form a developed image. The developed image, including colorant particles and carrier fluid, is transferred from the PIP to an intermediate transfer member (referred herein as a “blanket”). The blanket is heated until carrier fluid evaporates and colorant particles melt, and a resulting molten film representative of the image is then applied to the surface of the print substrate via pressure and tackiness. For printing with colored print agents, the printing device may include a separate developer system for each of the various colored print agents. There are typically two process methods for transferring a colored image from the PIP to the print substrate. One method is a multi-shot process method in which the process described in the preceding paragraph is repeated a distinct printing separation for each color, and each color is transferred sequentially in distinct passes from the blanket to the print substrate until a full image is achieved. With multi-shot printing, for each separation a molten film (with one color) is applied to the surface of the print substrate. A second method is a one-shot process in which multiple color separations are acquired on the blanket via multiple applications (each with one color) of liquid print agent in from the PIP to the blanket, and then the acquired color separations are transferred in one pass from the blanket to the print substrate.
The development station described above typically includes a set of electrodes to charge the electrostatic print agent, and a development roller to apply the charged print agent to the blanket. The proper electrical development of print agent particles within the developer system is dependent upon having and maintaining an expected gap between the electrodes and the surface of the developer roller. However, setting and maintaining a prescribed gap between the electrodes and the developer roller surface can be challenging as the gap distance can be influenced by variances in one or more of many components that make up the developer system. Any variation in the gap distance, both front to rear and/or back to head, may result in application of a non-uniform layer of print agent upon the blanket, therefore causing print defects on the print substrate.
To address these issues, various examples described in more detail below provide a system and a method that enables establishment of distances between developer roller surfaces and electrodes. In an example, a developer system for use in a LEP printer may include a housing and a developer roller that is to engage with a PIP to cause a transfer of the printing fluid to the PIP. The developer roller is rotatably connected to the housing, and includes a bearing to support and enable rotation of an axle attached to the developer roller, and includes a developer roller surface. The developer system includes first and second first electrodes disposed in the housing, the first and second electrodes to create an electrical charge, e.g., a potential bias, to cause transfer of printing fluid to the developer roller surface. In examples, the first and second electrodes are disposed in the housing such that the electrical charge causes transfer of the printing fluid to the developer roller surface along a neck between the first and second electrodes. The developer system includes a set of stop pins connected to the housing. The stop pins are to support the bearing and are to establish a first target distance between the developer roller surface and the first electrode and a second target distance between the developer roller surface and the second electrode.
In certain examples, the first target distance between the developer roller surface and the first electrode and the second target distance between the developer roller surface and the second electrode are a same distance.
In certain examples, the developer system includes a first bearing and a second bearing, and the set of stop pins includes a first set of stop pins connected to the housing to support the first bearing and to establish a first target distance between the first electrode and the developer roller surface, and includes a second set of stop pins connected to the housing to support the second bearing and to establish a second target distance between the second electrode and the developer roller surface.
In certain examples, the housing includes a first end cap and a second end cap, with each of the first and second electrodes attached to the first end cap, extending through the housing, and also attached to the second end cap. In such examples, the first bearing rests on the first endcap and the first set of stop pins are situated within the first endcap. The second bearing rests on the second endcap and the second set of stop pins are situated within the second endcap.
In certain examples, a set of stop pins includes an eccentric stop pin that is rotatable to a set of predefined positions, e.g., rotatable to a set of predefined positions according to mating holes in an end cap. In other examples, a set of stop pins includes a replaceable stop pin, e.g., a pin selected from a set of pins of different diameters.
In certain examples, the disclosed developer system may include a gap measurement component. The gap measurement component is to receive predicted distance data indicative of a predicted distance between the developer roller surface and the first electrode and a second predicted distance between the developer roller surface and the second electrode. The gap measurement component is to determine an attribute for each of the set of stop pins based upon the first and second predicted distances. In examples, the attribute may be position to which the stop pin has been rotated to influence or set a gap between a developer roller and an electrode. In certain examples, the attribute may be a predefined position for a stop pin according to mating elements in an end cap. In certain examples, the attribute may be a diameter of a stop pin, where the diameter is determined to be advantageous to setting a desired gap between a developer roller surface and an electrode. In certain examples, the gap measurement component is to receive predicted distance data indicative of a set of predicted distances between the developer roller surface and each of the first electrode and second electrode along the length of the developer roller surface, and is to determine the attribute for each of the set of stop pins based upon the set of predicted distances.
In this manner the disclosed developer system and method enables correction of manufacturing and assembly tolerances drift, and enables delivery of developer systems with accurate developer roller surfaces to electrodes gaps. Users of LEP printing systems will appreciate the high print quality made possible by the disclosed system and method for establishing distances between developer roller surfaces and electrodes. Manufacturers of LEP printing systems will enjoy that customer satisfaction is increased and reworking of developer systems is reduced, such that installations and utilization of LEP printers that utilize the disclosed system and method will be enhanced.
In the example of
In a particular example, a first eccentric first stop pin 118c and a second eccentric stop pin 118d are each rotatable to a plurality of predefined positions. In a particular example, the predetermined positions may be defined by mating elements 140 (e.g., holes or knobs) included in housing 102 (e.g. an end cap of housing 102). In yet another example, a first stop pin of developer system 100 may be an eccentric stop pin, wherein a second stop pin a non-eccentric or fixed gap stop pin. In yet another example, a first stop pin may be a non-eccentric or fixed gap pin, while a second stop pin is an eccentric stop pin. In yet another example, none of the stop pins is an eccentric stop pin.
A first set of stop pins, including first stop pin 118a and second stop pin 118b, is situated within the first endcap 202 and first bearing 114a rests on the first set of stop pins. The second set of stop pins, e.g., a third stop pin and a fourth stop pin, is situated within the second endcap (not visible in
In an example, the positioning and/or size of the first set of stop pins 118a 188b and of the second set of stop pins collectively establishes a first target distance (see 120
In the example of
In certain examples, a print agent capture tray 312 for catching unused print agent is formed near the bottom of the housing 102. Print agent may travel from a print agent reservoir, which may be located outside the developer system 100, between the first and second electrodes 110112 towards the developer roller 106. The developer roller 106 is to rotate in a first direction 306 shown in
In certain examples, developer system 100 may include, in addition to the developer roller 106, a squeegee roller 302. Squeegee roller 302 is to rotate in a second direction 308 opposite to the first direction of rotation of the developer roller 106, and is to be urged towards the developer roller 106 to compact and remove excess liquid from the print agent that coats developer roller surface 108. An electric charge may be applied, e.g., at the squeegee roller, to create an electric field between developer roller 106 and squeegee roller 302. The electric field is to further cause the print agent to be attracted to the developer roller surface 108, and to compact the print agent film formed thereon. The mechanical and electric forces applied from the squeegee roller 302 to the developer roller surface 108 are to cause the film of print agent on the developer roller surface to be of substantially uniform thickness.
Print agent that is not transferred from the developer roller 106 to the PIP 314 is referred to as unused print agent. In certain examples a cleaner roller 304 is disposed within the developer system 100 adjacent to the developer roller 106, and is to rotate in the second direction 308 opposite to the first direction rotation of the developer roller 106. Cleaner roller 304 is electrically charged and attracts electrically-charged print agent, cleaning unused print agent from the developer roller 106.
In certain examples, developer system 100 may also include a sponge roller 310, which includes an absorbent material, such as an open cell polyurethane foam sponge, mounted around a core. The sponge roller 310 is to rotate in the same direction as cleaner roller 304. In examples, sponge roller 310 is mounted adjacent to cleaner roller 304, such that, as the sponge roller 310 rotates, the absorbent material absorbs the unused print agent from the surface of the cleaner roller. In an example, unused print agent, including print agent caused to be removed from the developer roller by the collective operation of squeegee roller 302, cleaner roller 304, and/or sponge roller 310, may be drained from the print agent capture tray 312 and returned to the print agent reservoir.
In an example, distance data receipt engine 402 represents generally a combination of hardware and programming to receive distance data indicative of a predicted distance between a developer roller surface and a first electrode and a second predicted distance between the developer roller surface and a second electrode. The first and second electrodes are disposed in a housing and are for creating an electrical charge to cause transfer of printing fluid to the developer roller surface during a printing operation. The developer roller surface is a surface of a developer roller rotatably connected to the housing.
Determination engine 404 represents generally a combination of hardware and programming to determine an attribute for each of a plurality of stop pins based upon the first and second predicted distances. In an example where fixed-diameter stop pins are being utilized, the attribute may a diameter or size for a stop pin. In an example where eccentric stop pins are being utilized, the attribute may a predefined position or other setting for an eccentric stop pin. In a particular example, the attribute may be a predefined position according to a mating element (e.g., a mating hole) utilized to adjust diameter of an eccentric stop pin.
In certain examples, gap measurement component 400 may include an instruction engine 406. Instruction engine 406 represents generally a combination of hardware and programming to cause provision of a user instruction as to installing the plurality of stop pins according to the determined attributes. In an example where the user has access to a set of fixed diameter stop pins, the user instruction may be an instruction to select a specific-diameter stop pin from among the set and install such stop pin in the developer system 100 to establish a target distance between a developer roller surface and a first and/or second electrode of the developer system, In an example where the user has access to eccentric stop pins, the user instruction may be an instruction to set an eccentric stop pin to a specified setting, thereby adjusting the diameter of the eccentric stop pin to establish a target distance between a developer roller surface and a first and/or second electrodes of the developer system. In certain examples the user instruction may be communicated via an email or a system message (e.g. a text box, graphic, or other communication associated with an application). In other examples, the user instruction may be communicated via any other type of visual, auditory, or tactile communication.
Moving to
In a particular example, the predicted distance data received by distance data receipt engine 402 may be data generated utilizing a measuring device manufactured to a specification such that the measuring device can be temporarily installed at the developer system 100 such that the measuring device rests on end caps (e.g., upon the stop pins mounted to the end caps) in the same manner that the developer roller would rest on the end caps after assembly. In examples, the measuring device has circumference dimensions that are substantially the same as the development roller to be installed, and the measuring device is inserted into a position to be later occupied by the development roller. In certain examples the measuring device may be a laser measuring device with multiple lasers to measure distances between the developer roller surface 108 and the first and second electrodes.
In the foregoing discussion of
Memory resource 630 represents generally any number of memory components capable of storing instructions that can be executed by processing resource 640. Memory resource 630 is non-transitory in the sense that it does not encompass a transitory signal but instead is made up of a memory component or memory components to store the relevant instructions. Memory resource 630 may be implemented in a single device or distributed across devices. Likewise, processing resource 640 represents any number of processors capable of executing instructions stored by memory resource 630. Processing resource 640 may be integrated in a single device or distributed across devices. Further, memory resource 630 may be fully or partially integrated in the same device as processing resource 640, or it may be separate but accessible to that device and processing resource 640.
In one example, the program instructions can be part of an installation package that when installed can be executed by processing resource 640 to implement system 100 and gap measurement component 400. In this case, memory resource 630 may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory resource 630 can include integrated memory such as a hard drive, solid state drive, or the like.
In
According to the example of
Charging element 704 may include a charging device, such as corona wire, a charge roller, scorotron, or any other charging device. A uniform static charge is deposited on the PIP 702 by the charging element 704. As the PIP 702 continues to rotate, it passes an imaging unit 706 where one or more laser beams dissipate localized charge in selected portions of the PIP 702 to leave an invisible electrostatic charge pattern (“latent image”) that corresponds to the image to be printed. In some examples, the charging element 704 applies a negative charge to the surface of the PIP 702. In other implementations, the charge is a positive charge. The imaging unit 706 then selectively discharges portions of the PIP 702, resulting in local neutralized regions on the PIP 702.
Continuing with the example of
The print agent may be a liquid toner, comprising ink particles and a carrier liquid. The carrier liquid may be an imaging oil. The ink particles may be electrically charged such that they move when subjected to an electric field. Typically, the ink particles are charged such that they are repelled from the similarly charged portions of PIP 702, and are attracted to the discharged portions of the PIP 702.
The print agent is transferred from the PIP 702 to an intermediate transfer member blanket 708. The blanket may be in the form of a rotatable drum, belt or other transfer system. In a particular example, the PIP 702 and blanket 708 are drums that rotate relative to one another, such that the color separations are transferred during the relative rotation. In the example of
Once the layer of liquid toner has been transferred to the blanket 708, it is next transferred to a print substrate 716. This transfer from the blanket 708 to the print substrate may be deemed the “second transfer”, which takes place at a point of engage between the blanket 708 and the print substrate 716. The impression cylinder 710 can both mechanically compress the print substrate 716 in to contact with the blanket 708 and also help feed the print substrate 716. In examples, the print substrate 716 may be a conductive or a non-conductive print substrate, including, but not limited to, paper, cardboard, sheets of metal, metal-coated paper, or metal-coated cardboard.
Controller 718, discussed in more detail below, controls part, or all, of the print process. In examples, the controller 718 can control the voltage level applied by a voltage source, e.g., a power supply, to one or more of the imaging unit 706, the blanket 708, a drying unit, and other components of LEP printer 700.
An attribute for each of a plurality of stop pins is determined based upon the first and second predicted distances (block 804). Referring back to
A user instruction as to installing the plurality of stop pins according to the determined attributes is provided. The installed stop pins are to support bearings of the development roller and to establish target distances between the developer roller surface and the first and second electrodes (block 806). Referring back to
Although the flow diagram of
It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the blocks or stages of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features, blocks and/or stages are mutually exclusive. The terms “first”, “second”, “third” and so on in the claims merely distinguish different elements and, unless otherwise stated, are not to be specifically associated with a particular order or particular numbering of elements in the disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/018193 | 2/14/2018 | WO | 00 |
