Patent Grant
8805220
This application relates to commonly assigned, copending U.S. application Ser. No. 13/454,119, filed Apr. 24, 2012, entitled: “MULTI-TONER CHARGED AREA DEVELOPMENT METHOD”; U.S. application Ser. No. 13/454,117, filed Apr. 24, 2012, entitled: “MULTI-TONER DISCHARGED AREA DEVELOPMENT METHOD”, and U.S. application Ser. No. 13/454,119, filed Apr. 24, 2012, entitled: “PRINTER WITH MULTI-TONER CHARGED AREA DEVELOPMENT”, each of which is hereby incorporated by reference.
This invention pertains to the field of printing.
Color toner printers provide full color images by building up and sequentially transferring individual color separation toner images in registration onto a receiver and fusing the toner and receiver. Specific color outcomes are achieved in such printers because controlled ratios of differently colored toners are applied in combination to create the appearance of a desired color at specific locations on a receiver. Similarly, as is described in U.S. Patent Publication Number: US20090286177A1, entitled: “Adjustable Gloss Document Printing”, different toners such as high viscosity toners can be used in combination with lower viscosity toners to allow a user to obtain a desired gloss level at specific locations by controlling the ratio of two different types of toners at the locations. It will be appreciated that many other desirable printing outcomes can be achieved using ratio controlled combinations of toners.
In tandem type toner printers, separate toner images are generated in individual toner printing modules and the different toners to be applied at a specific location on a printer are combined when the separate toner images are transferred onto a common surface. Accordingly, variations in the way in which the individual toner printing modules generate toner images and variations in the registration of the individual toner images during transfer can create unintended combinations of toner.
It is a continuing objective in the toner printing arts to provide printing systems and methods that can reliably and controllably deliver precise combinations of two or more toners in very small controlled patterns on a receiver. This is driven among other things by requirements for increased image quality, security printing features such as authentication markings, and functional printing objectives. Accordingly, there is an ongoing desire in the printing industry to provide increasing smaller areas in which combinations of toners can reliably be formed in controlled patterns.
In toner printing, toner is developed on a surface having a charge pattern. In analog systems, a charge pattern is formed on the surface in response to an optical image. This form of image patterning can form any of a vast range of different image intensities and depending on the way in which the surface reacts to the image, the charge pattern can include an equally wide range of different charge patterns.
In digital printing systems, a digitally controlled writer generates a charge pattern. Such writers provide a fixed number of individually addressable areas which represent the smallest portions of the surface on which different charge levels can be defined by the writer. The writer also has a fixed number of writing levels that it can generate to form the charge pattern. For a given printing system, the size of the individually addressable areas is fixed as is the number of different charge levels that can be assigned to an individually addressable area.
What is needed in the art is a new approach to toner printing that enables the formation of controlled patterns of more than one toner at sizes that are smaller than the presently available addressable areas of such toner printers.
Printers are provided. In one aspect a printer has a print engine having a primary imaging member on which a charge pattern can be formed, and a writing system generating the charge pattern of a first polarity on a primary imaging member including a first area having a first imagewise modulated surface potential relative to ground and a second area having an imagewise modulated surface potential relative to ground that is at least about 30% greater than the first imagewise modulated surface potential so that an inter-area field forms having a component that extends from the second area into an edge proximate portion of the first area, a first development system and a second development system. The first development system partially develops the charge pattern with a first toner having a first polarity using a first development field to urge the first toner to develop in the first area in amounts that increase with increases in a first net development difference of potential between a first bias voltage at a first development station and a first imagewise modulated surface potential in the first area with the component of the inter-area field that extends into the first area further urging development of first toner in the edge proximate portion of the first area so that there is at least 15% more first toner per unit area in the edge proximate portion of the first area than in a remaining portion of the first area. The second development system further develops the charge pattern and a first toner image with a second toner having the first polarity using a second development field that urges the second toner to develop in the first area in amounts that increase with increases in a difference of potential between a second bias voltage and the first surface potential which is modulated by the charge of the first toner developed in the first area to urge the second toner to develop predominately in the remaining portion of the first area wherein the first toner and the second toner are different.
Toner 24 is a material or mixture that contains toner particles and that can form an image, pattern, or indicia when electrostatically deposited on an imaging member including a photoreceptor, photoconductor, or electrostatically-charged surface. As used herein, “toner particles” are the particles that are electrostatically transferred by print engine 22 to form a pattern of material on a receiver 26 to convert an electrostatic latent image into a visible image or other pattern of toner 24 on receiver 26. Toner particles can also include clear particles that have the appearance of being transparent or that while being generally transparent impart a coloration or opacity. Such clear toner particles can provide for example a protective layer on an image or can be used to create other effects and properties on the image. The toner particles are fused or fixed to bind toner 24 to a receiver 26.
Toner particles can have a range of diameters, e.g. less than 4 μM, on the order of 5-15 μm, up to approximately 30 μm, or larger. When referring to particles of toner 24, the toner size or diameter is defined in terms of the mean volume weighted diameter as measured by conventional diameter measuring devices such as a Coulter Multisizer, sold by Coulter, Inc. The mean volume weighted diameter is the sum of the volume of each toner particle multiplied by the diameter of a spherical particle of equal volume, divided by the total particle volume. Toner 24 is also referred to in the art as marking particles or dry ink. In certain embodiments, toner 24 can also comprise particles that are entrained in a liquid carrier.
Typically, receiver 26 takes the form of paper, film, fabric, metalized or metallic sheets or webs. However, receiver 26 can take any number of forms and can comprise, in general, any article or structure that can be moved relative to print engine 22 and processed as described herein.
Print engine 22 has one or more printing modules, shown in
Print engine 22 and a receiver transport system 28 cooperate to deliver one or more toner image 25 in registration to form a composite toner image 27 such as the one shown formed in
In
Printer 20 is operated by a printer controller 82 that controls the operation of print engine 22 including but not limited to each of the respective printing modules 40, 42, 44, 46, and 48, receiver transport system 28, receiver supply 32, and transfer subsystem 50, to cooperate to form toner images 25 in registration on a receiver 26 or an intermediate in order to yield a composite toner image 27 on receiver 26 and to cause fuser 60 to fuse composite toner image 27 on receiver 26 to form a print 70 as described herein or otherwise known in the art. Receiver transport system 28 can also advance receiver 26 to an optional finishing system 74 that can perform any of a wide variety of finishing operations on the print 70.
Printer controller 82 operates printer 20 based upon input signals from a user input system 84, sensors 86, a memory 88 and a communication system 90. User input system 84 can comprise any form of transducer or other device capable of receiving an input from a user and converting this input into a form that can be used by printer controller 82. Sensors 86 can include contact, proximity, electromagnetic, magnetic, or optical sensors and other sensors known in the art that can be used to detect conditions in printer 20 or in the environment-surrounding printer 20 and to convert this information into a form that can be used by printer controller 82 in governing printing, fusing, finishing or other functions.
Memory 88 can comprise any form of conventionally known memory devices including but not limited to optical, magnetic or other movable media as well as semiconductor or other forms of electronic memory. Memory 88 can contain for example and without limitation image data, print order data, printing instructions, suitable tables and control software that can be used by printer controller 82.
Communication system 90 can comprise any form of circuit, system or transducer that can be used to send signals to or receive signals from memory 88 or external devices 92 that are separate from or separable from direct connection with printer controller 82. External devices 92 can comprise any type of electronic system that can generate signals bearing data that may be useful to printer controller 82 in operating printer 20.
Printer 20 further comprises an output system 94, such as a display, audio signal source or tactile signal generator or any other device that can be used to provide human perceptible signals by printer controller 82 to feedback, informational or other purposes.
Printer 20 prints images based upon print order information. Print order information can include image data for printing and printing instructions from a variety of sources. In the embodiment of
In the embodiment of printer 20 that is illustrated in
In the embodiment of
In the embodiment of
Charging subsystem 120 is configured as is known in the art, to apply charge to photoreceptor 114. The charge applied by charging subsystem 120 creates a generally uniform initial surface potential VI relative to ground on photoreceptor 114. For the purposes of this discussion ground is considered to be zero volts. The initial surface potential VI has a first polarity which can, for example, be a negative polarity. Here, charging subsystem 120 includes a grid 126 that is selected and driven by a power source (not shown) to control the charging of photoreceptor 114. Other charging systems can also be used.
In this embodiment, an optional meter 128 is provided that measures the surface potential on primary imaging member 112 after initial charging and that provides feedback to, in this example, printer controller 82, allowing printer controller 82 to send signals to adjust settings of the charging subsystem 120 to help charging subsystem 120 to operate in a manner that creates a desired initial surface potential VI on primary imaging member 112. In other embodiments, a local controller or analog feedback circuit or the like can be used for this purpose.
Writing system 130 is provided having a writer 132 that forms charge patterns on a primary imaging member 112. In this embodiment, this is done by exposing primary imaging member 112 to electromagnetic or other radiation that is modulated according to color separation image data to form a latent electrostatic image (e.g., of a color separation corresponding to the color or colors of toner deposited at printing module 48) and that causes primary imaging member 112 to have image modulated charge patterns thereon.
In the embodiment shown in
As used herein, an “engine pixel” is the smallest addressable unit of primary imaging member 112. As shown in this embodiment primary imaging member 112 has a photoreceptor 114 that writer 132 (e.g., a light source, laser or LED) can expose with a selected exposure different from the exposure of another engine pixel. Engine pixels can overlap, e.g. to increase addressability in the slow-scan direction. Each engine pixel has a corresponding engine pixel location on an image and the exposure applied to the engine pixel location is described by an engine pixel level. The imagewise surface potential pattern is determined based upon the density of the color separation image being printed by printing module 48.
In the embodiments described herein, writing system 130 uses a write-black or discharged-area development (DAD) writing model where imagewise exposure of the primary imaging member 112 assumes that toner will develop on the primary imaging member at engine pixel locations in proportion to the extent to which the initial surface potential VI is discharged during writing. In such a system the amount of toner that is developed at an engine pixel location is generally proportional to the exposure at the engine pixel location. In the embodiment of
It will be appreciated that the process for converting image data into exposure levels to be generated by writer 132 are made in accordance with this DAD model and that any or all of printer controller 82, color separation image processor 104 and half-tone image processor 106 can be used to process image data, machine settings and printing instructions in ways that cause imagewise modulated surface potentials VEPL at each engine pixel location to be generated so that the desired toner image is formed on the primary imaging member 112.
After writing, primary imaging member 112 has an imagewise modulated surface potential VEPL at each engine pixel location that varies based upon the exposure level at the engine pixel location. In this embodiment, the imagewise modulated surface potential VEPL will be described as being between a greater imagewise modulated surface potential VG and a lesser imagewise modulated surface potential VL. The greater imagewise modulated surface potential can be at the initial surface potential VI reflecting in this embodiment, an image modulated surface potential VEPL at an engine pixel location that has not been exposed, while the lesser image modulated surface potential VL can be at a lesser level reflecting in this embodiment a lower image modulated surface potential VEPL at an engine pixel location that has been exposed by an exposure at an upper range of available exposure settings. For the purposes of this discussion the terms greater, higher, less, and lower are used. As used in this discussion these terms refer to an absolute value of the surface potential and the bias voltage. Likewise the terms increase and decrease will be used in reference to absolute values.
Another meter 134 is optionally provided in this embodiment and measures the surface potential within a non-image test patch area of photoreceptor 114 after the photoreceptor 114 has been exposed to writer 132 to provide feedback related to differences of potential created using writer 132 and photoreceptor 114. Other meters and components (not shown) can be included to monitor and provide feedback regarding the operation of other systems described herein so that appropriate control can be provided.
As is shown in
The first net development difference of potential VNET1 varies based on the image modulated surface potential VEPL at each engine pixel location and first bias voltage VB1. In a conventional DAD system, bias voltage VB1 is less than the initial surface potential VI. By subtracting the absolute value of the imagewise modulated surface potential VEPL at an engine pixel location from the absolute value of first bias voltage VB1, a positive value of VNET1 is obtained for the lesser imagewise modulated surface potential VL and a negative value is obtained for the greater imagewise modulated surface potential VG. For positive values of VNET1, the magnitude of the difference of potential VNET1 at an engine pixel location inversely corresponds to the magnitude of image modulated surface potential VEPL at the engine pixel location. The negative value of VNET1 produced at engine pixel locations corresponding to the greater imagewise modulated surface potential VG retards the deposition of first toner 158.
Accordingly, in the embodiment of
First development system 140 also has a first supply system 146 for providing the charged first toner 158 to first toning shell 142 and a first power supply 150 for providing the first bias voltage VB1 at first toning shell 142. First supply system 146 can be of any design that maintains or that provides appropriate levels of charged first toner 158 at first toning shell 142 during development. Similarly, first power supply 150 can be of any design that can maintain a first bias voltage VB1 as described herein. In the embodiment illustrated here, first power supply 150 is shown optionally connected to printer controller 82 which can be used to control the operation of first power supply 150.
First toner 158 on first toning shell 142 develops on individual engine pixel locations of primary imaging member 112 in amounts according to the first net development difference of potential VNET1. These amounts can, for example, increase along with increases in first net development difference of potential VNET1 for each individual engine pixel location and such increases can occur monotonically with increases in the first net development difference of potential VNET1. Such development produces a first toner image 25 on primary imaging member 112 having first toner quantities associated with the engine pixel locations that correspond to the magnitude of the first net development difference of potential VNET1.
The electrostatic forces that cause first toner 158 to deposit onto primary imaging member 112 can include Coulombic forces between charged toner particles and the charged electrostatic latent image, and Lorentz forces on the charged toner particles due to the electric field produced by the bias voltages.
In one example embodiment, first development system 140 employs a two-component developer that includes toner particles and magnetic carrier particles. In this embodiment, first development system 140 includes a magnetic core 144 to cause the magnetic carrier particles near first toning shell 142 to form a “magnetic brush,” as known in the electrophotographic art. Magnetic core 144 can be stationary or rotating, and can rotate with a speed and direction the same as or different than the speed and direction of first toning shell 142. Magnetic core 144 can be cylindrical or non-cylindrical, and can include a single magnet or a plurality of magnets or magnetic poles disposed around the circumference of magnetic core 144. Alternatively, magnetic core 144 can include an array of solenoids driven to provide a magnetic field of alternating direction. Magnetic core 144 preferably provides a magnetic field of varying magnitude and direction around the outer circumference of first toning shell 142. Further details of magnetic core 144 can be found in U.S. Pat. No. 7,120,379 to Eck et al., issued Oct. 10, 2006, and in U.S. Publication No. 2002/0168200 to Stelter et al., published Nov. 14, 2002, the disclosures of which are incorporated herein by reference. In other embodiments, first development system 140 can also employ a mono-component developer comprising toner, either magnetic or non-magnetic, without separate magnetic carrier particles. In further embodiments, first development system 140 can take other known forms that can perform development in any manner that is consistent with what is described and claimed herein.
As is shown in
The toner image 25 is transferred from primary imaging member 112 to transfer member 162. However, in this embodiment, adhesion forces such as van der Waals forces resist separation of toner image 25 from primary imaging member 112. In the embodiment of
Returning to
Second Development System
In this embodiment, second development system 200 has a second development station 201 with a second toning shell 204 and a magnetic core 212 which may rotate that provides a second developer having a second toner 208 near primary imaging member 112. Second toner 208 is charged and has a charge of the same polarity as first toner 158, the initial surface potential VI on primary imaging member 112 and any image modulated surface potential VEPL of the engine pixel locations. Second development station 201 also has a second toner supply system 206 for providing charged second toner 208 of the first polarity to second toning shell 204 and a second power supply 210 that provides a second bias voltage VB2 at second toning shell 202. Second toner supply system 206 can be of any design that maintains or that provides appropriate levels of charged second toner 208 at a second toning shell 204 during development. Similarly, second power supply 210 can be of any design that can maintain second bias voltage VB2 on second toning shell 204 as described herein. In the embodiment illustrated here, second power supply 210 is shown optionally connected to printer controller 82 which can be used to control operation of second power supply 210.
In general, printing modules 40-48 having such a second development system 200 can be operated as described above to create a first toner image 25 on photoreceptor 114 of primary imaging member 112 as is shown in
As is also shown in
Second toner 208 from second toning shell 204 deposits on individual engine pixel locations on primary imaging member 112 in an amount according to the second net development difference of potential VNET2. This amount can, for example, reflect the value of the second development difference of potential VNET2 and for positive values of VNET2 monotonically increases as a function of magnitude of the second net development difference of potential VNET2.
The electrostatic forces that cause second toner 208 to deposit onto primary imaging member 112 can include Coulombic forces between charged toner particles and the charged electrostatic latent image, and Lorentz forces on the charged toner particles due to the electric field produced between the bias voltage supplied to the second toning shell 204 and the surface potential at the engine pixel location modified by the charge of any first toner 158 developed at the engine pixel location. Second development station 201 can optionally employ a two-component developer or a one component developer and a magnetic core as described generally above with reference to first development station 141.
First development system 140 can be subject to development efficiency limitations. Theoretically, development of a charge pattern continues until VNET1 equals zero. However, it will be appreciated that under certain conditions, an amount of toner developed at an engine pixel location during development may be less than what is required to drive first net development difference of potential VNET1 to zero. The extent to which development of first toner 158 drives VNET1 to zero is known as development efficiency. A number of factors can influence development efficiency including charging conditions, toner concentration, toner delivery rate, development exposure times, environmental conditions and the like.
When there is a development efficiency of less than 100 percent at an engine pixel location and second development system 200 is active, a portion of the unused first net development difference of potential can be used to urge second toner 208 to develop at the engine pixel location. The amount of second toner 208 deposited at an engine pixel location therefore varies based upon the amount of first toner 158 at the engine pixel location.
Where the second bias potential VB2 is generally equal to the first bias voltage VB1, development of second toner 208 will continue until the second net development difference of potential VNET2 reaches or approaches a point where the second net development difference of potential VNET2 is zero. Because first development potential VB1 is equal to second bias voltage VB2 the second toner completes the development left uncompleted by the first toner.
Optionally, second bias potential VB2 can be greater than first bias potential VB1 and can also be greater that initial surface potential VI. When VB2 is greater than VI, a minimum controlled amount of second toner 208 is selectively applied to each of the engine pixel locations. This can be done to provide, for example, a coating of second toner for the image.
Second toner 208 is different than first toner 158. The difference can take many forms. In one embodiment first toner 158 can have first color characteristics while the second toner 208 has different second color characteristics. In one example of this type, first toner 158 can be a toner of a first color having a first hue and second toner 208 can be a toner having the first color and a second different hue.
First toner 158 and second toner 208 can have different material properties. For example, in one embodiment first toner 158 can have a first viscosity and the second toner 208 can have a second viscosity that is different from the first viscosity. In another embodiment, first toner 158 can have a different glass transition temperature than second toner 208. In one example of this type, the second toner 208 can have a lower glass transition temperature than first toner 158. In certain embodiments, second toner 208 can take the form of a toner that is clear, transparent or semi-transparent when fused. In other embodiments, second toner 208 can have finite transmission densities when fused.
First toner 158 and second toner 208 can be differently sized. For example, and without limitation, first toner 158 can comprise toner particles of a size between 4 microns and 9 microns while the second toner 208 can have toner particles of a size between 10 microns and 20 microns or more. First toner 158 and second toner 208 can also have other different properties such as different shapes, can be formed using different processes, or can be provided with additional additives, coatings or other materials known in the art that influence the development, transfer or fusing of toner.
As is shown in
In general a printer 20 having a printing module such as module 48 having a second development station 201 can be used to provide, a combination of a first toner 158 and a second toner 208 of a different type at an engine pixel location in a manner that automatically inversely adapts to an amount of first toner 158 on which the second toner 208 is applied and that automatically and precisely registers second toner 208 with first toner 158. This eliminates the risk that a first toner 158 to be applied at an engine pixel location will not be combined with a second toner 208 to be applied at the engine pixel location as a result of variations in the toner image as formed or as a result of misregistration during transfer.
A first bias voltage VB1 is established at first toning shell 142 using, in this example, first power supply 150. The first bias voltage VB1 is provided in a range between the higher surface potential VG and the lesser surface potential VL. This creates a first net development difference of potential VNET1 defined by the difference between the first bias voltage VB1 at first toning shell 142 and the image modulated surface potential VEPL at an individual one of the engine pixel locations on primary imaging member 112. The first net development difference of potential VNET1 for an engine pixel location is the first bias voltage VB1 less any image modulated surface potential VEPL at the engine pixel location (step 232).
Particles of first toner 158 having the first polarity are positioned between first toning shell 142 and the engine pixel locations so that the first net development difference potential VNET1 electrostatically urges first toner 158 to deposit at individual engine pixel locations according to the first net development potential VNET1 for the individual picture element locations (step 234).
A second bias voltage VB2 of the first polarity is established at second toning shell 204 using for example, second power supply 210. This creates a second net development difference of potential VNET2 between the second toning shell 204 and the individual engine pixel locations on primary imaging member 112. The second net development difference of potential VNET2 for the individual image pixel locations is the second bias voltage VB2 less the image modulated surface potential VEPL at the individual engine pixel location. If VB2 equals VB1 the second net development difference of potential VNET2 is less than VNET1 at engine pixel locations where first toner 158 has been developed in amounts that can range, for example, and without limitation, between about 25 and 50 percent of VNET1 (step 236).
When second bias voltage VB2 is supplied to second toning shell 204 a second net development difference of potential VNET2 arises between second bias voltage VB2 and the image modulated surface potential VEPL at individual engine pixel locations on primary imaging member 112 modified by the charge of any first toner 158 developed at the engine pixel location. The second net development difference of potential VNET2 at an engine pixel location is the second bias voltage VB2 less any image modulated surface potential VEPL at the engine pixel location and less any surface potential arising from any first toner 158 or second toner 208 at the engine pixel location.
Second toner 208 having the first polarity is positioned so that the field created by second net development potential VNET2 electrostatically urges second toner 208 to deposit on the engine pixel locations to form a second toner image 25 having second toner 208 at each picture element location in amounts that are modulated by the second net development potential VNET2 (step 238).
When second toner 208 is presented, the second bias voltage VB2 may be generally equal to the first bias voltage VB1 and less than an initial surface potential VI on the primary imaging member 112. This causes an amount of second toner 208 to deposit on individual engine pixel locations having the first toner 158 according to the second net difference of potential VNET2 between second bias voltage VB2, the potential provided by the charge of any first toner 158 at an individual engine pixel location and the image modulated potential VEPL at the individual engine pixel locations. For positive values of VNET2, when second net development difference of potential VNET2 increases the amount of second toner 208 increases.
However, since second bias voltage VB2 is not greater than initial surface potential VI and generally equal to VB1, no second toner 208 deposits on portions of primary imaging member 112 that are unexposed during writing and that therefore have the initial surface potential VI. Thus, using the method and the bias levels of
When primary imaging member 112 is moved past first development station 141, first toner 158 deposits at engine pixel location 252 in an amount that is determined by the first net development difference of potential VNET1 between first bias voltage VB1 and an imagewise modulated surface potential VEPL at engine pixel location 252. The surface potential at engine pixel location 252 changes because of the deposition of first toner 158 and the surface potential after development of first toner 158, the first toner modulated surface potential VFT, is the imagewise modulated surface potential at engine pixel location 252 that has been modified by the charge associated with the deposited first toner 158. In theory, first toner 158 would deposit at engine pixel location 252 until VFT equals VB1, but a development shortfall 262 arises due to a development efficiency that is less than unity.
As is further shown in
In this embodiment, second bias voltage VB2 is set at a level that is generally equal to first bias voltage VB1 and not greater than initial surface potential VI. Accordingly, the amount of second toner 208 that deposits on an individual engine pixel location 252 during second development is modulated by the first toner modulated surface potential VFT that includes the charge associated with first toner 158 that is at engine pixel location 252. The second toner 208 is applied to each of the engine pixel locations in an amount that is modulated, at least in part based on first toner modulated surface potential VFT caused by a first toner 158 at the engine pixel location. This result is achieved without requiring the use of a separate printing module and the attendant need to generate an image to be printed by the separate printing module to apply second toner 208 in an imagewise fashion.
When primary imaging member 112 is moved past first development station 141, first toner 158 deposits at engine pixel location 254 until the first toner 158 at engine pixel location 254 produces a first toner modulated surface potential VFT that is generally the same as first bias voltage VB1 less a development shortfall 272 that arises due to development efficiency being less than 100 percent.
As is further shown in
In this embodiment, second bias voltage VB2 is set at a level that is generally equal to first bias voltage VB1 but not greater than initial surface potential VI. Accordingly as has been illustrated in
Similarly, for the purposes of
As is shown in
However, as is shown in
It will be appreciated from this that in this example of a printing module having a writing system 130 that writes according to a DAD model and that has the first development system 140 and second development system 200 as disclosed herein and that provides an initial surface potential of VI that is generally greater than first bias voltage VB1 and a second bias voltage VB2, second toner 208 will not be attracted to engine pixel locations such as engine pixel location 250 of
In this way, second toner 208 can be used to provide an uppermost layer of any engine pixel location having first toner 158 developed thereon. These layers can then be transferred to a receiver 26 using transfer subsystem 50 and fused. This can provide a toner image with controlled surface properties such as improved wear resistance, consistent gloss, and protection against ultraviolet radiation, chemical contamination and the like.
Further, precise registration of the second toner 208 with the first toner 158 at individual engine pixel location becomes possible without requiring imagewise placement of the second toner 208 because the electrostatic forces that urge transfer of an amount of the second toner 208 to an engine pixel location such as engine pixel locations 250, 252 or 254 automatically develop desired amounts of second toner 208 at these engine pixel locations as a function of the same difference of potential at the engine pixel location VEPL used to develop the first toner and as a function of first toner actually located on the primary imaging member 112.
As is also shown in the example of
In certain embodiments, it can be useful for a printer 20 to generate prints 70 that have, effectively, an overcoat of second toner 208 even in portions of receiver 26 that do not have first toner 158 developed thereon. This can be done, for example, where receiver 26 has a post fused gloss that is not consistent with the post fused gloss of a second toner 208. In such a case or for other reasons, adjustment of the second bias voltage VB2 above the initial surface potential VI allows coverage of the receiver 26 with second toner 208.
This is illustrated in
As can be seen from
As has been discussed elsewhere herein the second bias voltage VB2 exceeds the first bias voltage VB1. In one embodiment second bias voltage VB2 exceeds the first bias voltage VB1 by at least about 25 percent. This advantageously creates a relatively thick layer of second toner 208, and further allows additional second net development difference of potential VNET2 during the development of second toner 208 to enable higher efficiency development at least during a portion of the second development.
In the embodiments described above, second toner 208 has been described as being applied onto one or more first toners 158. First toner 158 is referred to in various places as a color toner, or has been described as providing differently colored toners or that form images according to color separation images. This has been done for convenience only and is not limiting. A first toner 158 can be applied according to any type of image or pattern and the color of the first toner 158 is not critical. Without limitation, a first toner 158 can be applied according to any first toner pattern such as a pattern that defines a structure that is to be formed on receiver 26 or an arrangement of toners that are of a type or that are applied in patterns that are intended to achieve functional outcomes such as forming structures, optical elements, electrical circuit components or circuits or desirable arrangements of biological material or components thereof.
Development of Inter-Area Fields
As is shown conceptually in
Accordingly, as is shown in
However, as is also illustrated in
It will be appreciated from this that in the early stages of development of a first toner 158 in first area 452 using a DAD model first toner 158 develops predominantly in edge proximate portion 492 where the development is influenced both by the development field 470 and the inter-area field 460.
However, as development of charge pattern 450 continues, first toner 158 in edge proximate portion 492 accumulates and an accumulated charge of first toner 158 begins to offset the influence of inter-area field 460. This reduces the strength of inter-area field 160 so that during a second stage of development there is more balanced development of first toner 158 between edge proximate portion 492 and remaining portion 490. As is shown in
Continuing development of first area 452 can form an accumulation of charged first toner 158 in edge adjacent portion 492 that can have the effect of further reducing or neutralizing the influence of inter-area field 460 and therefore reducing the strength of the field that urges first toner 158 to develop in edge adjacent portion 492. This can cause development of first toner 158 between edge proximate portion 492 and remaining portion 490 to cease favoring development in edge adjacent portion 492. First toner image 484 shown in
In accordance with the method of
There is a variety of ways in which development of first toner 158 can be made to provide partial development. For example, in one embodiment, at least one of a concentration of first toner 158, an amount of time allowed for development of a charge pattern 450 using first toner 158, a conductivity of a developer in which first toner 158 is prepared for development, or a rate of rotation of a rotating magnetic core used to induce development enhancing behavior in the developer (as is known in the art) are reduced to limit the extent to which first toner 158 develops. In one embodiment, printer controller 82 causes one or more of these conditions to occur.
In other embodiments, a distance between a source of first toner 158 such as toning shell 142 and primary imaging member 112 can be set to limit the extent to which first toner 158 develops the charge pattern. In still other embodiments, a conductivity of a carrier (not shown), or a delivery or a rate at which first toner 158 is supplied for development can be modified to provide controlled partial development of first toner 158. Here too, in one embodiment, printer controller 82 controls first development system 140 to cause such effects. Such approaches to allow first development system 140 to provide a partial development of first toner 158 can be implemented manually or automatically by way of control of appropriate sensors and actuators by printer controller 82.
Charge pattern 450 and the first toner image 480 are further developed with a second toner 208 having the first polarity. This development is done using a second development field that urges the second toner to develop in the first area in amounts that increase with increases in a difference of potential between a second bias voltage and the first imagewise modulated surface potential modified by the charge of the first toner developed in the first area to urge the second toner to develop predominately in the remaining portion of the first area that is not proximate the edge (step 406).
As is shown in this embodiment, during second development an amount of second toner 208 that is developed will reflect the second net development difference of potential VNET2 which in turn will reflect the image modulated surface potential VEPL(492) of first engine pixel location 452 less any surface potential provided by the charge of any first toner 158. Accordingly, second toner 208 will develop in first area 452 in quantities that are inversely proportional to the quantities of first toner 158 previously developed. This allows second toner 208 to develop to form a second toner image 25 having a size that is smaller than the size of first area 452 or having a shape that is different than a shape or a size of first area 452.
First toner 158 and second toner 208 are then fused to the receiver (step 408) and optionally finished (step 410). These steps can be performed in any conventional manner.
It will be appreciated that such inter-area fields can arise along any edge of an area on a primary imaging member 112 and can cause first toner 158 to show enhanced development along any edge. For example, as is shown in
As is shown in
As can also be seen in
Similarly,
The effects shown in these illustrations are visible effects that arise after partial development a first toner 158 which is illustrated as a dark toner and a further development using a second toner 208 which is illustrated as a white toner in first area 610.
As is shown in
Similarly, as is shown in
In
In the example that is shown in
It will be appreciated that by partially developing any of charge patterns 450A-450H using white first toner 158 followed with development of a dark second toner 208 and fusing, it is possible to reverse each of the effects illustrated in
There are a variety of other ways in which the method of
In the examples that are discussed above the first bias potential VB1 and the second bias potential VB2 have been described as being less than the initial surface charge VI. This prevents development of first toner 158 and second toner 208 in second area 454 or third area 459 if VNET1 and VNET2 have sufficiently negative values, however, this is optional.
In other embodiments the second bias voltage VD2 can be greater that the first bias potential VB1 and the greater imagewise modulated surface potential VG.
It will be appreciated that in the above described embodiments various charge patterns have been shown that enable the creation of various effects in the arrangement of a first toner and a second toner in a first area. In some cases, it may be that the image data to be printed includes image elements that induce such effects. In other cases, the process of determining a chart pattern can include a step of creating edges that are not incorporated in the image data to be printed with such edges being provided to create field gradients that form specific image effects in a printed image. Such created edges can be introduced automatically or manually. In one embodiment, printer controller 82 can detect areas of image data to be printed that include gradients and cause charge patterns to be developed that provide gradients within such areas that have improved smoothness by virtue of the use of field gradients such as those described so that smooth transitions can be made between density levels within a gradient forming area of an image.
In the embodiments described above, second toner 208 has been described as being applied onto one or more first toners 158. First toner 158 is referred to in various places as a color toner, or as a toner that provides differently colored toners or that form images according to color separation images. This has been done for convenience only and is not limiting. A first toner 158 can be applied according to any type of image or pattern and the color of the first toner 158 is not critical. Without limitation, a first toner 158 can be applied according to any first toner pattern such as a pattern that defines a structure that is to be formed on receiver 26 or an arrangement of toners that are of a type or that are applied in patterns that are intended to achieve functional outcomes such as forming structures, optical elements, electrical circuit components or circuits or desirable arrangements of biological material or components thereof.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
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| Number | Date | Country | |
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| 20130279949 A1 | Oct 2013 | US |
