Patent Application
20130084115
This invention pertains to the field of printing.
In toner printing a pattern of toner particles is formed and transferred to a receiver. The transferred toner particles are then fused to create adhesive bonds between the toner particles and between the toner particles and the receiver. In most commercial applications, fusing is performed using a process known as contact fusing. In a contact fusing system, the pattern of toner particles and the receiver are passed through a nip between a heated roller and a pressure roller. The heated roller and the pressure roller are biased toward each other and press the pattern of toner particles and the receiver together while the heated roller heats the toner particles and the receiver. The pressure and heat applied during fusing creates the adhesive bonds that form a fused toner image that is bound to the receiver.
Adhesive bonds also arise between the toner particles and the heated roller during contact fusing. Where the adhesive bonds between the toner particles and the heated roller are weaker than the adhesive bonds between the toner particles within the toner image and the adhesive bonds between the toner particles and the receiver, the toner particles separate from contact with the heated roller, remain on the receiver, and cool to form the fused toner image. However, where the adhesive bonds between the heated roller and the toner particles are stronger than the adhesive bonds between the toner particles in the toner image or when the adhesive bonds between the heated roller and the toner particles are stronger than the adhesive bonds between the toner particles, and the receiver, toner particles can separate from the toner image and adhere to the heated roller. This is known as toner offset. Toner offset creates unwelcome artifacts in the toner image being fused by removing toner necessary for the toner image that is being fused. Further, the toner that remains on the heated roller creates unwelcome artifacts in subsequently fused images by transferring to later toner prints or by forming relief patterns in such later formed toner images.
In some toner printers, elongated belts are used for fusing that have the effect of reducing toner offset. One example of this is described in U.S. Pat. No. 5,256,507 (issued Oct. 26, 1993, in the name of Aslam et al). As is described in the '507 patent, an elongated web is heated to fuse the toner image and then cooled to facilitate ready separation of the receiver member with the toner image fixed thereto from the elongated web. The elongated web arrangement also serves to increase the glossiness of the toner image. As a result, this arrangement is particularly useful for multi-color toner image fusing.
Alternatively, other toner printers apply a fusing oil to the heated roller in order to reduce the adhesion between the heated roller and the toner. However, the use of such oil creates new press operating requirements by requiring additional handling of the oil and by requiring procedures and equipment to ensure that oil is applied in a consistent manner. Additionally, at least some of the fusing oil can transfer from the heated roller onto the print creating a print having image quality and handling problems.
In another alternative, toner printers have been developed that use toner particles that incorporate a wax. During fusing such toner particles are heated at least to a glass transition temperature of the toner and to an incorporated melting temperature of the incorporated wax. This causes the wax to liquefy and to separate from the pattern forming material to form a slip layer between the toner particles and a heated fuser roller. The slip layer reduces extent of adhesive bonds between the heated fuser roller and the toner particles and lowers the likelihood of toner offset. However, after fusing, the wax remains on the toner image and creates gloss and image density variations that can lower the perceived quality of toner images made using toners of this type. This is a particular problem with high gloss images that require high fusing temperatures.
One alternative approach is to remove wax from the toner image during fusing. For example, JP2005043532A entitled: “A fixing apparatus and an image forming device” describes a fixing apparatus having a heating roller wherein any surplus amount of wax is removed from the toner image by being drawn into pores in the heating roller. Similarly, JP2006091146A entitled: “An Image Forming Device and a Fixing Apparatus” describes toner image is formed using the toner containing a resin binder, a coloring material and the wax for improving the releasability. In these publications a wax bearing toner is transferred onto a recording sheet and the toner is fixed by a fixing device under heat and pressure. The fixing device has a heating roller in the form of a hollow cylindrical member made of a metal and has a large number of pores extending from the peripheral face of the heating roller and to the hollow part thereof.
According to the '532 publication, when toner is heated, the melting wax forms a layer and is drawn into the pores by capillary action and removed. The wax is absorbed by a glass fiber layer formed inside the heating roller and held. The '532 publication further suggests that since the excess of wax is removed from the surface of the toner image, the gloss unevenness is restrained without making the toner image remarkably highly glossy even when the toner image is suddenly cooled after fixing.
Another approach is shown in JP2005266079A entitled: “Image Forming Apparatus, Wax Removal Device and Image Forming Method”. The '079 publication describes the use of a wax removal part that allows a blade to contact the surface of a recording medium that is at a temperature range not lower than the melting point of the wax included in toner and lower than the melting point of the toner material. The blade removes the melted wax on the surface of the recording medium. A distance between the fixing device and the blade is determined so that the recording medium causes a temperature drop in accordance with the conveyance and the temperature of the surface falls into the temperature range.
Another publication, JP 2002-091205A entitled: “Image forming apparatus” describes another printer with a wax removal system. In one embodiment the wax removal system has a rolling-up (continuous) type web cleaning device and a film anchorage device that positions the web for cleaning. According to the '205 publication, the wax on a recording medium can fully be cleaned by placing a web on a cleaning roller and rolling the cleaning roller in a direction that is the reverse of a direction of movement of a recording medium. The web can be a porous body material which comprises a natural or natural fibrous body or polyester, polypropylene, polyethylene, etc. However, other webs can be used.
The '205 publication also notes in order to acquire a picture without the further loss of density and gloss caused by wax, the cooling temperature in an exfoliation point is lower than the softening temperature of this recording-medium resin, and it is desirable that it is higher than the melting point of a wax. The '205 publication further notes that it will become granular (the wax which began to melt from a toner in this intermediate transfer body and this recording-medium interface) and will adhere on this recording medium after exfoliation if it exfoliates at a temperature lower than wax melting point temperature under the state where this intermediate transfer body and this recording medium touch.
In general then, the approaches of the '507, '146, '079 and '205 publications attempt to resolve the wax problem by cleaning wax from the surface of the toner image. However, it will be appreciated that attempting to fully clean wax from the surface of a toner image can create a risk of damaging the toner image as generally such cleaning processes involve cleaning structures that are held against the toner image while applying cleaning forces to remove the wax from the toner image. Such cleaning processes pose a particular risk of damaging portions of the toner image that have significant variations in toner stack heights such as regions of high density color where many different types of toner are applied or in regions where toner is applied to build toner stack heights that are high enough to create tactile effects.
The risks of damaging the toner image are particularly acute when such cleaning is performed when the toner is at an elevated temperature. Yet in each of the '536, '136, '079 and '205 publications wax removal is performed when the wax is heated to a temperature sufficient to liquefy the wax. As the wax is in intimate contact with the toner image, this necessarily involves removing wax when the toner image is at an elevated temperature and is more vulnerable to damage.
For example, in the '536 and '136 publications, wax is cleaned at the fusing nip while the wax is in a liquid form and the toner is at or above the glass transition temperature for the toner. These in-the-nip cleaning approaches can be compromised by the risk that the fusing process will interfere with the wax cleaning process, and by the risk that the wax cleaning process will reduce the effectiveness of the fusing process. These in-the-nip cleaning approaches further require the use of complex heating roller designs that are capable of removing such wax while also providing heat and pressure to the toner image in the nip.
Similarly, in the '079 publication and the '205 publication, the toner image is allowed to cool below a glass transition temperature for the toner but while the wax is heated above the melting temperature of the wax. As an initial matter, these approaches are only useful for toners that have wax components with wax melting temperatures that are below a glass transition temperature of the toner. Further, these approaches risk damaging the toner image because they require the application of cleaning forces to the toner image when the temperature of the wax is above a melting temperature of the wax and the temperature of the underlying toner is at or close to the same elevated temperature.
What is needed in the art therefore are new methods, fusing systems and printers that enable a toner image to be formed using a toner with a wax while also managing the presence of any such wax on the toner image to eliminate density and gloss variations that without creating damaging the toner image.
Wax management systems are provided. In one aspect a wax management system has print positioning system having an input to receive a fused toner print having a toner image with a viewing surface that has first portions with wax globules and second portions without wax globules and a print positioning apparatus that arranges the print for wiping by a wiping system having a wiping surface that wipes the viewing surface to move at least some of the wax from the wax globules in the first portion onto the second portion. A wax management device controller determine when the received toner image is at a temperature where the toner image is below a glass transition temperature of the toner and the wax is below a melting temperature for the wax and to position the received fused toner print for wiping. The controller causes the wiping system to wipe the fused toner print after the controller determines that the fused toner print is at a temperature where the toner image is below a glass transition temperature of the toner and the wax is below a melting temperature for the wax.
Toner 24 can include one or more polymeric binder resins (toner resins) which can be optionally colored by one or more colorants. Colorants which can be pigments, dyes, and other limited wavelength light absorbers suitable for use in the practice of the present invention are disclosed, for example, in U.S. Reissue Pat. No. 31,072, and in U.S. Pat. Nos. 4,160,644; 4,416,965; 4,414,152; and 4,229,513. As the colorants, known colorants can be used. The colorants include, for example, carbon black, Aniline Blue, Calcoil Blue, Chrome Yellow, Ultramarine Blue, Du Pont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, C.I. Pigment Red 48:1, C.I. Pigment Red 122, C.I. Pigment Red 57:1, C.I. Pigment Yellow 185, C.I. Pigment Yellow 155, C.I. Pigment Yellow 97, C.I. Pigment Yellow 12, C.I. Pigment Yellow 17, C.I. Pigment Blue 15:1, and C.I. Pigment Blue 15:3. Colorants can generally be employed in the range of from about 1 to about 90 weight percent on a total toner powder weight basis, and preferably in the range of about 2 to about 40 weight percent, more preferably from 4 to 30 weight percent, and most preferably 6 to 20 weight percent in the practice of this invention. When the colorant content is 4% or more and preferably 6% or more by weight, a sufficient coloring power can be obtained, and when it is 30% or less and more preferably 20% or less by weight, good transparency can be obtained. Mixtures of colorants can also be used. Colorants in any form such as dry powder, its aqueous or oil dispersions or wet cake can be used in the present invention. Colorant milled by any methods like media-mill or ball-mill can be used as well. The colorant may be incorporated, e.g., in the oil phase of limited coalescence process, or in the first aqueous phase of a multiple emulsion process as disclosed in U.S. Publication No. 2010/0021838.
The toner resin can be selected from a wide variety of materials including both natural and synthetic resins and modified natural resins as disclosed, for example, in U.S. Pat. Nos. 4,076,857; 3,938,992; 3,941,898; 5,057,392; 5,089,547; 5,102,765; 5,112,715; 5,147,747; 5,780,195 and the like, all incorporated herein by reference. Preferred resin or binder materials include polyesters.
Known binder resins are useable as the polymeric binder. These binder resins include, e.g., homopolymers and copolymers such as polyesters, styrenes, e.g. styrene and chlorostyrene; monoolefins, e.g. ethylene, propylene, butylene and isoprene; vinyl esters, e.g. vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; alpha.-methylene aliphatic monocarboxylic acid esters, e.g. methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and dodecyl methacrylate; vinyl ethers, e.g. vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; and vinyl ketones, e.g. vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Particularly desirable binder polymers/resins include polystyrene resin, polyester resin, styrene/alkyl acrylate copolymers, styrene/alkyl methacrylate copolymers, styrene/acrylonitrile copolymer, styrene/butadiene copolymer, styrene/maleic anhydride copolymer, polyethylene resin and polypropylene resin. They further include polyurethane resin, epoxy resin, silicone resin, polyamide resin, modified rosin, paraffins and waxes. Also, especially useful are polyesters of aromatic or aliphatic dicarboxylic acids with one or more aliphatic diols, such as polyesters of isophthalic or terephthalic or fumaric acid with diols such as ethylene glycol, cyclohexane dimethanol and bisphenol adducts of ethylene or propylene oxides.
In a toner printer 20 that uses an electrophotographic print engine 22, toner 24 takes the form of toner particles that are charged and developed in the presence of an electrostatic latent image to convert the electrostatic latent image into a visible image. Toner particles without colorant can provide, for example, a protective layer on an image or that impart a tactile feel or other functionality to the printed image. Toner 24 has toner particles that include at least a polymeric binder resin and a wax at least some of which can separate from the toner particles to reduce adhesion between the toner particles and a heated fuser roller.
Toner particles can have any of a variety of ranges of median volume diameters, e.g. less than 8 μm, on the order of 10-15 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 median volume weighted diameter as measured by conventional diameter measuring devices such as a Coulter Multisizer, sold by Coulter, Inc. The volume weighted diameter is the sum of the mass of each toner particle multiplied by the diameter of a spherical particle of equal mass and density, divided by the total particle mass. Toner 24 is also referred to in the art as marking particles or dry ink.
Typically receiver 26 takes the form of paper, film, fabric, metal bearing films, metal bearing fabrics, or metallic sheets, fibers or webs, and can be made from naturally occurring materials or artificial materials. 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.
In the embodiment of
In the embodiment of
In the embodiment of
Each toner image 25 is transferred to a respective transfer subsystem 50 that presses toner image 25 against receiver 26 while subjecting toner image 25 to an electrostatic field that urges toner image 25 to transfer onto receiver 26. In other embodiments, printer 20 can use a print engine 22 that forms a toner image 25 on receiver 26 in any other manner consistent with what is claimed herein.
After toner image 25 is transferred to receiver 26, receiver 26 is moved by receiver transport system 28 to fuser 60.
In the embodiment of
Returning to
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. Communication system 90 can connect to external devices 92 by way of a wired or wireless connection. In certain embodiments, communication system 90 can comprise any circuit that can communicate with one of external devices 92 using a wired connection such as a local area network, a point-to-point connection, or an Ethernet connection. In certain embodiments, communication system 90 can alternatively or in combination provide wireless communication circuits for communication with separate or separable devices using, for example, wireless telecommunication or wireless protocols such as those found in the Institute of Electronics and Electrical Engineers Standard 802.11 or any other known wireless communication systems. Such systems can be networked or point to point communication.
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 toner printer 20. For example and without limitation, one example of such external devices 92 can comprise what is known in the art as a digital front end (DFE), which is a computing device that can be used to provide an external source of a print order that has image data and, optionally, production data including printing information from which the manner in which the images are to be printed can be determined. A print order that is generated by such external devices 92 is received at communication system 90 which in turn provides appropriate signals that are received by printer controller 82 for use in determining operation of printer 20.
Similarly, the print order or portions thereof including image and production data can be obtained from any other source that can provide such data to printer 20 in any other manner, including but not limited to memory 88. Further, in certain embodiments image data and/or production data or certain aspects thereof can be generated from a source at printer 20 such as by use of user input system 84 and an output system 94, such as a display, audio signal source or tactile signal generator or any other device that can be used by printer controller 82 to provide human perceptible signals for feedback, informational or other purposes.
To investigate the gloss and density variation problems that are associated with the use of toners having a wax component, the inventors have made test prints with a toner 24 having a polyester binder resin, wax, and colorant using a toner printer 20 of the electrophotographic type. Test prints were prepared for several different toners with test patches of a single toner type having 200% toner laydown and fused. The process speed was 10 ppm and the receiver on which the toner was provided was Utopia Gloss 270 gsm sold by Appleton Coated LLC, Combined Locks, Wis., USA.
Similarly, test prints have been made with a toner 24 having a wax and these test prints have been fused at a higher fusing temperature than the test prints shown in
As is shown in
To the extent that fused toner image 132 has one or more toners with a colorant therein such as a pigment or dye, certain wavelengths of light 138 and receiver reflected light 140 will be absorbed in part or in whole by these colorant(s). Toner combinations are selected for use in making a toner image such that when fused toner image 132 is exposed to light, fused toner image 132 absorbs particular wavelengths to cause light 142 that emerges from viewing surface 130 to have a desired color content.
As is also shown in
As is also shown in
Accordingly, when a light 160 confronts upper boundary 154 a first portion of light 160 is reflected by upper boundary 154 in a generally specular manner at an angle determined by a tangent of the curvature of upper boundary 154 to form a wax gloss reflection 162. Wax gloss reflection 162 is reflected in a direction that is different from the direction of toner gloss reflection 136. This creates a variation in the apparent gloss of fused toner image 132 in the region of . the wax globule 152.
A second portion 164 of light 160 passes into wax globule 152 at upper boundary 154 and travels through wax globule 152 at an angle that is determined by the index of refraction of air proximate and the index of refraction of wax globule 152 as well as the angle of incidence of light 160. To the extent that wax 150 is not colorless and to the extent that wax 150 may have non-uniform wax densities or porosity or other materials therein, a portion of light 164 will be absorbed by wax globule 152. Further, wax globule 152 can cause a portion of light 164 to be diffused within wax globule 152 such as by reflection, local illumination or absorption and reemission or other known optical effects. Such effects cause light 166 to appear to reflect or to be emitted from within wax globule 152. Light 166 can have the effect of reducing the apparent density of the portion of fused toner image 132 under wax globule 152.
The remaining portion of light 164 then crosses lower boundary 156 and travels as light 168 at an angle that is determined by the angle of incidence of light 168, the index of refraction of wax 150 and the index of refraction of the toner forming fused toner image 132. As is also illustrated here there can be a secondary toner gloss reflection 169 when light 164 reaches viewing surface 130. However, secondary gloss reflection 169 travels along a different path than toner gloss reflection 136.
Light 168 then travels through fused toner image 132, is partially absorbed by any colorants in fused toner image 132 and is then reflected by receiver 26. The reflection can occur in a more specular manner when receiver 26 is more reflective and in a more diffuse manner when receiver 26 is less reflective. Here a generally specular reflection is illustrated. A portion 170 of light 168 is then reflected by receiver 26 and passes through fused toner image 132 a second time. Again, to the extent that there is any colorant in fused toner image 132, a portion of light 170 is also absorbed so that a smaller portion of light 170 passes through viewing surface 130 of fused toner image 132 and back into wax globule 152 as light 172. Light 172 passes through wax globule 152 at an angle that is determined according to the angle of incidence of light 172 at the lower boundary 156, the index of refraction of wax 150, and the index of refraction of fused toner image 132.
To the extent that the material forming wax globule 152 absorbs light in a non-uniform manner and to the extent that wax globule 152 may have non-uniform wax densities or porosity or other materials therein, a portion of secondary gloss reflection 169 and light 172 will be absorbed by wax globule 152. Further, to the extent that wax globule 152 can cause a portion of secondary gloss reflection 169 and light 172 to be reflected or reemitted within wax globule 152 such as by reflection, local illumination, absorption and reemission, or other known optical effects a portion of secondary gloss reflection 169 will be reemitted as light 173 and a portion of light 172 as light 174 both apparently from within wax globule 152.
Light 174 travels at an angle that is determined by the angle of incidence of light 172, the index of refraction of wax 150 and the index of refraction of air or whatever medium surrounds wax globule 152. It will be noted that the angle of incidence is generally determined according to a tangent taken at the upper boundary 154 of wax globule 152. Similarly, any remaining portion of secondary gloss reflection 169 passes through upper boundary 154 to become light 171 that travels at an angle that is generally determined by the angle of incidence of secondary gloss reflection 169, the index of refraction of wax 150 and the index of refraction of air or whatever medium surrounds wax globule 152. Here too, the angle of incidence is determined according to a tangent taken at upper boundary 154 of wax globule 152.
It will be appreciated from this that the presence of wax globule 152 creates a number of effects on light that is incident on fused toner image 132 that can negatively impact the gloss of a fused toner image 132. These include at least providing specular reflection of light 160 as wax gloss reflection 162 that is directed along a path that is not parallel to toner gloss reflection 136, providing a secondary toner gloss reflection 169 that creates a light 171 that is also not parallel to toner gloss reflection 136. Additionally, the wax itself can have a different reflectance than toner 24 used to form fused toner image 132. These effects create variations in the gloss of viewing surface 130 of fused toner image 132 between the first portions 146 and second portions 148 of fused toner image 132 that generally reduce the apparent gloss of the fused toner print 120.
Additionally, it will be appreciated that the presence of wax globule 152 can also negatively impact image densities in fused toner print 120. In particular, wax globules 152 create uneven illumination of fused toner image 132. Wax globules 152 can also create image independent low density areas where there is light emission from the wax globules 152. Wax globules 152 also reduce the apparent sharpness of fused toner image 132 by causing localized variations in the path of travel of light through wax globule 152.
It will also be appreciated that these effects are exacerbated by the irregular, indistinct, or blob-like form of wax globules 152. In particular, the form of wax globules 152 significantly influences the direction of gloss producing reflections, and further alters a path of travel of light that passes through wax globule 152 to cause secondary gloss reflections to occur in directions that are inconsistent with a direction of toner gloss reflections. Further the form of wax globules 152 can provide areas within a single wax globule 152 where light that travels through wax globule 152 is reflected differently or has a greater opportunity for deflection, internal reflection or reemission than light that strikes other portions of wax globule 152. This can enhance the above described effects and therefore make the gloss and density variations caused by such effects more evident.
However, the fundamental challenges associated with efforts to fully remove wax 150 from a fused toner image 132 remain. Specifically, while improvements in gloss and in image density sought after by the prior art are desired, it is unacceptable to attempt to remove wax in a way that risks damaging viewing surface 130 of fused toner image 132.
Accordingly, toner printer 20 of
A useful consideration in selecting wax 150 is the melting temperature of wax 150. In certain embodiments, wax 150 can have a melting point above the glass transition temperature of toner 24. It is generally preferred to have the melting point of wax 150 above the toner glass transition temperature but below the fusing temperature since this will allow the toner to enter a glassy state before the wax melts. This allows wax 150 to melt upon contact with a heated contact surface such as heated roller 72 to form slip layer that reduces adhesion between toner 24 and the contact surface. The thermal characteristics of toner 24, such as a glass transition temperature of toner 24 and an incorporated wax melting point of a wax 150 that is incorporated into a toner 24, can be determined by conventional methods, e.g., differential scanning calorimetry (DSC). Here, the endothermic peak temperature is defined as a melting point of a wax. If a wax has multiple peaks, the melting point is the lower peak temperature.
A wax 150 with a very high melting point can require higher fusing temperatures and can hinder the speed at which toner image 25 will be fused. A wax 150 having a very low melting point can limit the durability of the post fused image, particularly where a toner 24 having such a low melting point wax is fused at a high fusing temperature. In one embodiment wax 150 has a melting point temperature that is 5 degrees Celsius greater than a glass transition temperature of toner 24. In other embodiments, wax 150 can have a melting point that is less than 100 degrees Celsius.
Examples of such waxes include polyolefins such as polyethylene wax and polypropylene wax, and long chain hydrocarbon waxes such as paraffin wax. Another class of waxes is carbonyl group containing waxes which can include long-chain ester waxes. The waxes WE-3 and WE-8 made by NOF Corporation of Japan are long-chain ester waxes made from long-chain fatty acids and alcohol. These waxes are preferred in certain embodiments because they have a narrow melting range and have melting points that are above typical toner glass transition temperatures of the binder resins in many conventional toners and further have melting points that are less than 100 degrees Celsius. For example, WE-3 has an unincorporated single melting point peak of 70.8 degrees Celsius while WE-8 has two endothermic peaks of 71.8 and 80.2 degrees Celsius for an unincorporated melting point of 71.8 degrees Celsius. In certain embodiments, the glass transition temperature of the binder polymer can be between about 40 degrees Celsius and 80 degrees Celsius. In other embodiments, the glass transition temperature of the binder resin more typically between about 45 degrees Celsius and 70 degrees Celsius. In still other embodiments, the glass transition temperature of the binder resin can be between about between 50 degrees Celsius and 65 degrees Celsius.
In the embodiment of
A contact surface is used to apply heat and pressure to heat toner 24 forming toner image 25 at least to a glass transition temperature of the toner 24 and to heat wax 150 at least to an incorporated melting temperature of incorporated wax 150 (step 202). This causes at least some of wax 150 to separate from toner 24 to reduce adhesion between heated roller 72 and toner 24. In toner printer 20, fusing is done can be done as is described above using fuser 60 where the contact surface comprises heated roller 72. However in other embodiments, such a contact surface can take the form of a heated belt or platen or any other heated surface that directly contacts a toner image 25 during fusing.
Toner image 25 is allowed to cool below a glass transition temperature of toner 24 to form a fused toner image 132 having a viewing surface 130 and wax 150 is allowed to cool below a melting point of the wax 150 to form wax globules 152 (step 204) so that after cooling viewing surface 130 has first portions 146 with wax globules 152 and second portions 148 without wax globules 152. As is also discussed above, the presence of wax globules 152 causes first portions 146 and second portions 148 to reflect and transmit incident light in different ways and to have a first gloss and a second gloss, respectively that are different. As is discussed above, wax globules 152 can also cause density variations. In certain embodiments, controller 82 operates fuser 60, transport 103, and wax management system 100 so that wax management is performed after the toner image and the wax have been allowed to cool below the glass transition temperature of the toner and the melting temperature for wax 150. This can be done in a variety of ways and the exact manner of cooling is not critical. In one embodiment, the distance between fuser 60 and wax management system 100 and the rate of transport between fuser 60 and wax management system 100 can be selected to allow cooling when controller 82 causes transport to occur. In other embodiments, controller 82 can drive cooling system 105 and transport system 103 in ways that allow the cooling to occur. Other embodiments are possible.
In
This is particularly true where, as shown for wax globules 152A and 152C in
Viewing surface 130 of fused toner image 132 is then wiped to move at least some of wax 150 from wax globules 152 in first portions 146 to second portions 148 (step 206). This can have the effect of reducing the extent to which wax 150 is organized into globules. This can also yield gloss and density improvements. Further, this can reduce the extent of differences between the gloss of first portions 146 and the gloss of second portions 148.
In this embodiment wiping system 250 comprises a wiping surface support 252 that supports a woven and compressible wiping surface 254 by way of an optional resilient intermediary 256 such as resiliently deformable foam. Wiping surface 254 can take any of a variety of forms and can comprise, for example, a paper, a fabric, a woven material, a polyester sheet or a fibrous surface or a polymeric or other form of material which itself can be compressible. Wiping surface 254 can be used repeatedly or cleaned or replaced as necessary. In the embodiment that is illustrated in
In the embodiment of
As performed here the wiping moves wax 150 from wax globules 1520 in first portions 146 onto second portions 148. This reduces the height or increases the radius of curvature of wax globules 152 in order to reduce the optical effects caused by wax globules 152. This improves the gloss of fused toner image 132 and makes the gloss response of first portions 146 and second portions 148 more consistent. Additionally, during wiping a portion of wax 150 moved from a wax globule may remain on wiping surface 254 and may be disposed in other ways. However, removal of all or substantially all of wax 150 sufficient to clean viewing surface 130 is not required. Accordingly, wiping system 250 need not apply sufficient force against viewing surface 130 to clean wax 150 from viewing surface 130. For example, wiping surface 254 can be supported by a resilient intermediary 256 that can be resiliently compressed so that wiping surface 254 will apply a limited amount of force during wiping that is insufficient to damage viewing surface 130. The resilient compressibility of the resilient intermediary 256 can be such that a wax globule 152 can cause wiping surface 254 to conform at least in part to the shape of wax globule 152. Where this occurs, the wiping force can be sufficient to remove only a part of wax 150 from a wax globule 152 and to reposition wax 150 from first portions 146 on which wax globule 152 rests to the second portions 148 of viewing surface 130.
The inventors have simulated the effects of a single pass multi direction wiping process manually. In this regard the test prints giving rise to the toner images shown in
In examples 1 and 2, a first type of binder designated as BR1 was used. BR 1 comprises linear polyesters of bisphenol A and terephthalic acid. In examples 3 and 4 a second type of binder designated BR2 was used that comprised a blend of linear, cross-linked and branched polyesters of bisphenol A and terephthalic acid. The 15:3 Phthalocyanine Blue colorant levels associated with the BR1 and BR2 were 3.9 and 4.4 weight percent respectively.
All gloss measurements shown in Table I are G-60 gloss measurements determined using a Gardener Micro-TRI-Gloss 20-60-85 Glossmeter available from BYK, Gardner River Park, Maryland, USA. Toner glass transition temperature and incorporated wax melting point temperature were determined from a second heating cycle of an 8 to 12 mg. toner sample using a differential scanning calorimeter (Q100 manufactured by IA Instruments of New Castle Delaware). The toner sample was treated by raising its temperature to 150 degrees Celsius at a heating rate of 10 degrees Celsius/min. cooling the sample at a cooling rate of 20 degrees Celsius/min. to 25 degrees Celsius and thereafter heating the sample at a heating rate of 10 degrees Celsius/min. to 150 degrees Celsius.
These results show that there has been a substantial increase in gloss performance using these wiping techniques. Further, it will be noted that, although not measured, a density increase in the wiped patches was also observed.
The effects of such wiping are further illustrated in
Although it is difficult to see any wax 150 in the form of wax globules 152 in
In this regard,
These conditions improve the gloss of fused toner image caused by wax globules 152 at least in part by reducing the extent of any relief patterns caused by wax globules 152 and optionally can be established so that that after cooling the fused toner image 132 has a viewing surface 130 with heights that vary within a range of viewing surface heights and wherein after wiping viewing surface 130 and wax 150 on viewing surface 130 have a range of total heights that is within the range of variations of viewing surface heights so that any additional height provided by the wax 150 on viewing surface 130 does not increase the extent of any gloss variations beyond the variations caused by variations in the height of viewing surface 130.
This reduces gloss variations by diminishing the scattering of light caused by different angles of specular reflection created by upper boundaries 154A, 154B and 154C of wax globules 152A, 152B and 152C and further reduces the extent to which a beam of light must travel through wax in a wax globule thereby reducing the opportunity for the light to be reflected or deflected by materials in the wax thus improving gloss. Further to the extent that such gloss variations caused by wax 150 on viewing surface 130 continue to exist after wiping, these effects are more evenly distributed across the viewing surface 130 and therefore create less of a variation. For similar reasons, density variations cause by wax 150 and in particular by wax globules 152 will be reduced.
Further it will be appreciated that the overall extent of height variations along viewing surface 130 can be reduced in this manner in some instances. As is shown in
In other embodiments wax management system 100 can take other forms. For example, as is shown in
In other embodiments, wiping surface 254 can be a web such as is described above that is supported by roller 280.
In one embodiment the surface of roller 280 is elastomeric and is sufficiently resiliently compressible such that a wax globule 152 can cause a wiping surface 254 to conform at least in part to the shape of wax globule 152. Where this occurs, the force applied by the roller 280 can be sufficient to move only a part of any wax 150 forming wax globules152 from first portions 146 to second portions 148 of viewing surface 130.
Wax management system 100 can be integrated into a printer 20 or can act as a standalone device that receives toner prints from printer 20 and that manages the wax thereon in line with printer 20 as a standalone device that can be used as needed. In this regard, printer 20 can have a wax management system 100 that is integral to toner printer 20 or wax management system 100 can be separable from toner printer 20 such as a modular attachment. In still another embodiment, printer 20 can be use with a stand alone wax management system 100 that can be used to manage wax 150 on fused toner prints made by toner printer 20 but that can be used in cooperation with printer 20 or without any connection with toner printer 20.
It will be appreciated that such a standalone embodiment can be used to perform wax management on fused toner prints 120 on an as needed basis and on fused toner prints 120 that have been printed hours, days or months before being submitted for wax management. Further, it will be appreciated that such stand alone embodiments of wax management system 100 can manage wax 150 on a viewing surface 130 of a fused toner image 132 without requiring that wax 150 be in a liquefied state. This allows such stand alone embodiments to be used without requiring that fused toner image 132 be at an elevated temperature required to heat wax 150 above a melting temperature for wax 150.
In this embodiment, print positioning system 300 also has a print positioning apparatus 310 that is used to position fused toner print 120 for wiping by a wiping system 250. Here, print positioning apparatus 310 comprises a carrier surface 312 that carries fused toner print 120 from input 302 past an arrangement of guides 314 and 316 that contact sides of fused toner print 120 to position fused toner print 120 for wiping. In the embodiment illustrated carrier surface 312 comprises a slide surface that uses gravity to draw fused toner print 120 from input 302 to a wiping surface 318 where fused toner print 120 is positioned for wiping by a wiping system 250. However, in other embodiments, carrier surface 312 can be, for example, an endless belt, a powered arrangement of rollers, or any other known conveyance systems that can cause a fused toner print 120 to move from one position to another.
As is also shown in
As is also shown in
A first temperature sensor system 308 and a second temperature sensor system 322 are shown in
In the embodiment of
Wax management system controller 330 then determines when the fused toner image 120 is at a temperature where fused toner image 132 is below a glass transition temperature of the toner 24 forming fused toner image 132 and wax 150 is below a melting temperature for wax 150. In this embodiment, this is done using first temperature sensing system 308 positioned in input 302. When wax management system controller 330 determines that fused toner print 120 is not at an appropriate temperature, wiping of the fused toner print 120 can be delayed to allow cooling. Additionally, optional cooling system 320 can be activated to accelerate such cooling.
After it is determined that a fused toner print 120 is at a temperature where fused toner image 132 is below a glass transition temperature of the toner 24 and the wax 150 is below a melting temperature for wax 150, wax management system controller 330 can cause print positioning apparatus 310 to position fused toner print 120 for wiping. Wax management system controller 330 then causes print positioning apparatus 310 to move cooled fused toner print 120 to wiping system 250. Once fused toner print 120 is positioned relative to wiping system 250, wax management system controller 330 causes wiping system 250 to cause wiping surface 254 to wipe viewing surface 130 to move at least some of wax 150 from wax globules 1.52 in first portion 146 onto second portion 148.
Alternatively, wax management system controller 330 can cause print positioning apparatus 310 to move fused toner print 120 to wiping system 250 and can cause wiping system 250 to delay wiping until second temperature sensor system 322 sends signals to wax management system controller 330 from which wax management system controller 330 can determine that fused toner image 132 is below a glass transition temperature of toner 24 and wax 150 is below a melting temperature for wax 150. In this alternative embodiment, second temperature sensing system 322 can be used to monitor the temperature of any fused toner print 120 at wiping system 250.
It will be appreciated by those of skill in the art that first temperature sensor system 308 and second temperature sensor system 322 can be used in various combinations to provide signals to wax management controller 332 to allow wax management system controller 330 to ensure that wax management is not performed until the toner forming toner image 24 is below a glass transition temperature of toner 24 and wax 150 is below a melting temperature for wax 150.
In other embodiments, other methods can be used to ensure that wiping is performed when fused toner image 132 is below a glass transition temperature of the toner 24 and the wax 150 is below a melting temperature for wax 150, such as by providing a cooling system 320 that is capable of cooling any fused toner print to the desired conditions for wiping, or by transporting the fused toner print 120 such that sufficient time has been allowed for the fused toner print 120 to reach a condition where fused toner image 132 is below a glass transition temperature of the toner 24 and the wax 150 is below a melting temperature for wax 150.
It will also be understood that wax management system controller 330 can determine that fused toner image 132 is below a glass transition temperature of toner 24 and wax 150 is below a melting temperature for wax 150 in ways that do not require temperature sensing. For example, wax management system controller 330 can receive information from which wax management system controller 330 can determine that conditions indicate that cooling is sufficient. Examples of such information include but are not limited to data from which an amount of time since fusing can be determined, data from which an elapsed travel distance since fusing, can be determined or data that indicates that cooling has been performed by toner printer 20 before transfer to wax management system 100.
In the embodiment of
As is further shown in this embodiment, wax management system 100 has an optional gloss sensor system 340 with one or more light emitters 342 that apply a light 344 to viewing surface 130 and that has one or more light sensors 346 that are positioned to detect the extent to which viewing surface 130 reflects light 344 as a specular reflection 348. The amount of light sensed by light sensors 346 is then used by wax management system controller 330 or by a local gloss sensor controller (not shown) to determine an extent of the gloss of portions of viewing surface 130. It will be appreciated that gloss sensor system 340 can take the form of any other device that can be used to measure the gloss of a surface.
In one embodiment, a wax management system controller 330 can cooperate with cooling system 320, second temperature sensor system 322, gloss sensor system 340 and wiping system 250 so that wax management system controller 330 can control the wiping process based upon signals from the gloss sensor system 340, such as by determining a number of times that wiping is performed or determining a combination of different directions of the wiping based upon signals from gloss sensor system 340.
It will be appreciated that any other embodiment of wax management system 100 including those that are incorporated into a toner printer 20 or those that are incorporated into modules that are intended for use with but that are separable from toner printer 20 can also incorporate a cooling system 320, a wax management system controller 330 or a gloss sensor system 340 and/or any other features, methods or aspects of the embodiment of
It will also be appreciated that where wax management system 100 is part of, is joined to or is otherwise in communication with a toner printer 20 any functions ascribed herein as being performed by wax management system controller 330 can be performed by printer controller 82.
This application relates to commonly assigned, copending U.S. application Ser. No. ______ (Docket No. K000631RRS), filed ______, entitled: “PRINTER WITH WAX MANAGEMENT SYSTEM”; U.S. application Ser. No. ______ (Docket 96670RRS), filed ______, entitled: “METHOD FOR MANAGING WAX ON A PRINT” each of which is hereby incorporated by reference.
