Adjustment of temperature in a hot roller

Provided is a printing device comprising a hot roller having an inside surface and an outside surface. A heating element is present within the hot roller. The inside surface has a first region, wherein the first region is coated with a first type of material. The inside surface has a second region, wherein the second region is coated with the first type of material, and wherein second region is of a different dimension than the first region. The inside surface has a third region, wherein the third region is coated with a second type of material.

BACKGROUND

The disclosure relates to a method and system for the adjustment of temperature in a hot roller.

In certain laser printers, a laser draws the printable image on a special light-sensitive optical photo conducting drum. The light sensitive drum collects powdered ink, also referred to as toner, using an electrostatic charge and allows the toner to be transferred to a page of paper. The dry, powdery toner has to be melted to become a permanent image on the page. To melt the toner, the page is rolled between a hot fuser roller, also referred to as a hot roller, and at least one unheated pressure roller, also referred to as a backup roller. One or more infrared lamps, such as halogen lamps, included inside the hot roller may heat the hot roller up to a temperature high enough to melt and fuse the toner to the page.

For example, the IBM* Infoprint* 4100 comprises a continuous forms printing system that has two electrophotographic printers, called engines, which allow printing on both sides of the paper. In the IBM Infoprint 4100, the toner is electrostatically deposited onto a photoconductive drum and then transmitted electrostatically to the paper. The paper then travels between two rollers, a hot roller and a backup roller, which apply heat and pressure respectively to fuse the toner to the paper. In the IBM Infoprint 4100, the page also flows over a preheated platen, where the preheated platen is used to preheat the paper before the paper reaches the hot roller, in order to aid in achieving the necessary paper temperature for the toner to fuse correctly. The hot roller may be an aluminum tube coated with a layer of silicon rubber. There are four internal tungsten quartz filament lamps of different length and position inside the hot roller, which collectively heat the hot roller. The backup roller is also an aluminum tube, but without heating elements. The backup roller applies pressure to fuse the toner to the paper. Due to the soft nature of the silicon rubber coating, when the hot roller and backup roller are in contact, they may form a nip area of approximately 10 mm. This allows for sufficient area and time to fuse the toner to the paper. To prevent the toner from adhering to the hot roller, the hot roller is coated with silicon oil. This is accomplished from a cloth material saturated in the oil. When the printer is running, the cloth is in contact with the hot roller. A smaller positioning roller may be used to optimize the paper direction before the paper proceeds between the hot roller and backup roller. * IBM and Infoprint are trademarks or registered trademarks of International Business Machines Corporation

SUMMARY OF THE DESCRIBED EMBODIMENTS

Provided is a printing device comprising a hot roller having an inside surface and an outside surface. A heating element is present within the hot roller. The inside surface has a first region, wherein the first region is coated with a first type of material. The inside surface has a second region, wherein the second region is coated with the first type of material, and wherein second region is of a different dimension than the first region. The inside surface has a third region, wherein the third region is coated with a second type of material.

In additional embodiments, the second type of material absorbs less heat from the heating element in comparison with the first type of material. In further embodiments, the first type of material is black paint, and the second type of material is aluminum.

In still further embodiments, the printing device is a first printing device, wherein in the first printing device the differences of temperature between different regions of the outside surface of the hot roller is decreased in comparison to a second printing device in which identical material is used to coat the inside surface of any hot roller in the second printing device.

In certain embodiments of the printing device, the dimensions of the first region, the second region, and the third region are determined based on temperatures profiles measured on the outside surface of the hot roller. In additional embodiments of the printing system, the entire inside surface is coated with the second type of material, and the first type of material is coated over the second type of material on the first and second regions of the inside surface. In further embodiments of the printing device the first region and the second region are located adjacent to two edges of the hot roller.

In yet additional embodiments, the printing device further comprises a toner, wherein the toner is fused to paper by the hot roller, wherein the printing device is a first printing device, and wherein in the hot roller in the first printing device fuses the toner more uniformly over the paper in comparison to a second printing device in which the inside surface of any hot roller in the second printing device is coated with identical material.

Provided is a laser printer, comprising, a hot roller having an inside surface and an outside surface. The hot roller has a heating element within the hot roller. The inside surface of the hot roller is made from a first type of material. A second type of material absorbs heat generated by the heating element better in comparison to the first type of material. The hot roller further comprises a first region of the inside surface, wherein the second type of material coats the first type of material in the first region. The hot roller further comprises a second region of the inside surface, wherein the second type of material coats the first type of material in the second region.

In certain embodiments of the laser printer, a third region of the inner surface is left uncoated. In additional embodiments of the laser printer, dimensions of the first region, the second region, and the third region are determined based on temperature profiles measured on the outside surface of the hot roller. In further embodiments of the laser printer, the first type of material is aluminum and the second type of material is black paint.

In certain embodiments, the laser printer is a first laser printer, wherein in the first laser printer the differences of temperature between different regions of the outside surface of the hot roller is decreased in comparison to a second laser printer in which identical material is used to coat the inside surface of the hot roller.

In additional embodiments of the laser printer, the first region and the second region are located adjacent to two edges of the hot roller.

Provided is a method, wherein a determination is made of the temperature variation across a hot roller in a printing device. A plurality of regions of the hot roller is determined from the temperature variation, wherein temperature in the determined plurality of regions is relatively lower in comparison to other regions of the hot roller. The plurality of regions of the hot roller is coated with a material that allows the coated plurality of regions to absorb more heat in comparison to the other regions of the hot roller.

In certain embodiments of the method, the material is black paint, wherein the hot roller whose plurality of regions has been coated with black paint has more uniform temperature after being coated with black paint. In other embodiments of the method, at least two of the determined plurality of regions are located adjacent to two edges of the hot roller. In further embodiments of the method, areas adjacent to the edges of the hot roller have a lower temperature before the coating of the plurality of regions. In certain embodiments of the method, after the coating of the plurality of regions the differences of temperature between different regions of the hot roller is decreased in comparison to the differences of temperature between the different regions of the hot roller before the coating of the plurality of regions.

DETAILED DESCRIPTION

Electrophotographic printers, such as laser printers, may have non-uniform temperatures across hot rollers included in the printers. The non-uniform temperature may cause incomplete fusing of toner while printing. In certain implementations, the temperature is not uniform across the roller, and the temperature across the roller varies beyond a predetermined threshold. If the temperature of the hot roller is not large enough, the toner may not completely adhere to the paper. On the other hand, if the roller is too hot, the paper may wrinkle.

Poor fusing of toner to paper can occur when using a hot roller fusing system in a laser printer. The poor fusing can occur because the temperature at the edge of the hot roller may be lower than the temperature in the middle, and the lower temperature may not provide adequate heat to fuse the toner at the edges of paper. Certain embodiments allow the temperature at the edges of a hot roller to be made higher at the edges than in the middle. In certain other embodiments, the temperature profile across a hot roller may be made more uniform by painting certain regions of the hot roller with heat absorbent material.

In certain embodiments, the inside surface of the hot roller is painted black to promote radiation heat transfer to the hot roller. In certain embodiments the painting of the inside of the hot roller is varied to enhance radiation heat transfer at the edges of the hot roller, by using a pattern of black painted and unpainted regions.

FIG. 1illustrates a block diagram of a printing device, such as a laser printer100, in accordance with certain embodiments. The laser printer100includes a hot roller102that is also referred to as a hot roll, and a backup roller104that is also referred to as a backup roller. Toner106and paper108may be added to the laser printer100in a manner known in the art.

In certain embodiments, the paper108is guided (reference numeral110) between the hot roller102and the backup roller104. The toner106is transferred to the surface of the paper108via electrostatic fusion (reference numeral112).

While a laser printer has been illustrated inFIG. 1, alternative embodiments may be implemented on other printing devices, such as, fax machines, photocopiers, etc. Furthermore, whileFIG. 1shows the paper108being guided (reference numeral110) between the hot roller102and the backup roller104, in alternative embodiments the paper108may be guided under or over the hot roller, with or without any backup roller104being present.

FIG. 2illustrates a block diagram of a hot roller102inside the laser printer100, in accordance with certain embodiments.

The hot roller102may be shaped in the form of a cylinder. The hot roller102may include an infrared source200, where in certain embodiments the infrared source100includes one or more lamps, such as tungsten quartz filament lamps. The one or more lamps that comprise the infrared source200are located in one or more hollow cavities inside the hot roller. The infrared source200can heat up the hot roller102.

During the printing process, the paper108is guided under the hot roller102and the heat applied by the hot roller102in association with the pressure applied by the backup roller104transfers the toner106to the paper108. The guidance of the paper108under the hot roller102is indicated inFIG. 2by the three arcs202a,202b, and202c. As the paper108is guided under the hot roller202, the process of printing takes paces through the transfer of the toner106to the paper108.FIG. 2shows the region of the paper108on which printing has taken place, and this region of the paper108on which printing has taken place may be referred to as the printed part204of the paper108.FIG. 2also shows the region of the paper108on which no printing has taken place, and this region of the paper on which no printing has taken place may be referred to as the unprinted part206of the paper108.

The hot roller102has two edges, referred to as a first edge208and a second edge210. The two edges208,210may form the two circular ends of the cylinder that comprises the hot roller102. In certain embodiments, the two edges208,210may be referred to as left and right edges of the hot roller. The length212of the hot roller102is also shown inFIG. 2, where the maximum width of the paper108cannot exceed the length212of the hot roller102. In alternative embodiments, paper that has a width less than the length212of the hot roller102may be used for printing. In such alternative embodiments one end of the paper108may be aligned with the first edge208of the hot roller102, and the other end of the paper may not reach the second edge210of the hot roller102.

FIG. 3illustrates a diagram of temperature profile in the exemplary hot roller102before the hot roller102has been painted, and painted regions on the inside surface of the hot roller102, in accordance with certain embodiments.

InFIG. 3, the graph300shows the temperature profile along the longitudinal axis of the hot roller102, wherein the longitudinal axis of the hot roller102is the longitudinal axis of the cylinder that comprises the hot roller102.

The X-axis302of the graph300indicates the distance304from the first edge208of the hot roller102, and the Y-axis306of the graph300indicates the temperature308that has been measured on the surface of the hot roller102at various distances from the first edge208of the hot roller. The maximum distance shown along the X-axis202is the length212of the hot roller102.

FIG. 3shows that the temperature profile310along the longitudinal axis of the hot roller102as measured by measuring devices that measure temperatures on outside surface of the hot roller102. The temperature profile310may be determined experimentally by operating the laser printer100under a variety of experimental conditions. The temperature profile310shown inFIG. 3is an exemplary temperature profile and other embodiments may cause other temperature profiles to be generated.

In the temperature profile310the temperature is shown to vary along different distances from the first edge308of the hot roller204. For example, temperatures next to the first edge208and the second edge210are relatively lower than in certain other regions along the longitudinal axis of the hot roller102. The maximum temperature difference312shown in the graph300is the difference between the maximum and minimum temperature along the longitudinal axis on the outside surface of the hot roller102.

The graph300has been drawn for a hot roller102in which the inside surface of the hot roller102is either not coated or coated with the same type of material. For example, in certain embodiments the inside surface of the hot roller102is made of aluminum and is not coated. In other embodiments, the inside surface of the hot roller102is made of steel and is coated with aluminum.

As can be observed from the graph300, the hot roller102may exhibit non-uniform temperature on the surface of the hot roller102. The non-uniform temperature may cause incomplete fusing of toner while printing. For example, if the temperature of the hot roller102is not high enough, the toner may not completely adhere to the paper. On the other hand, if the roller is too hot, the paper may wrinkle. The poor fusing can occur because the temperature at the edge of the hot roller may be lower than the temperature in the middle, and the lower temperature may not provide adequate heat to fuse the toner at the edges of the paper108. A more uniform hot roller temperature may improve the fusing of the toner while printing. Furthermore, the coating on a hot roller may be thermally stressed in the higher temperature regions such that a failure of the coating may limit the useful life of the hot roller. In certain embodiments, a more uniform temperature for the hot roller can also lead to a longer component life for the hot roller.

Certain embodiments allow the temperature at the edges of a hot roller to be made higher at the edges than in the middle. In certain other embodiments, the temperature profile across a hot roller may be made more uniform by painting certain regions of the hot roller with heat absorbent material. For example, certain regions of the inside surface of the hot roller102may be painted with black paint, and an exemplary hot roller314whose regions in the inside surface have been painted with black paint is shown inFIG. 3. The regions that have been painted with black paint may be the relatively cooler regions as determined from the temperature profile310.

In the painted hot roller314, the inside surfaces close to the first edge208and the second edge210are painted with relatively wide black regions314,316in comparison to relatively narrower black regions, such as black regions318,320,322, that are painted on insides surfaces away from the edges208,210of the hot roller102. The black paint on the inside surface of the hot roller102may allow relatively better absorption of heat radiation from the infrared source200and may cause the temperature profile along the longitudinal axis of the hot roller102to become more uniform in comparison to the temperature profile310. For example, if the temperature profile along the longitudinal axis of the hot roller102is measured for the painted hot roller314, the maximum temperature difference between the highest and the lowest temperature along the longitudinal axis of the painted hot roller314may be less than the maximum temperature difference312before painting the hot roller.

Therefore,FIG. 3illustrates certain embodiments in which the inside surface of the hot roller102is painted black to promote radiation heat transfer to the hot roller102. In certain embodiments, the painting of the inside of the hot roller102is varied to enhance heat transfer at the edges using a pattern of black painted and unpainted regions. InFIG. 3reference numeral324indicates how regions are painted black on the inside surface of the hot roller on the basis of the temperature profile310.

FIG. 4illustrates painted regions on the inside surface of an exemplary painted hot roller400, in accordance with certain embodiments. InFIG. 4the inside surface402of the hot roller400is painted with strips of black paint. For example, in certain embodiments, the black painted regions are the regions indicated by reference numerals404,406,408,410,412,414: The black painted regions404,406,408,410,412,414may absorb relatively more heat from the infrared source200than the unpainted regions416,418,420,422,424,426.

In alternative embodiments, the regions404,406,408,410,412,414may be coated with or made of a first type of material and the regions416,418,420,422,424,426may be coated with or made of a second type of material, where the first type of material absorbs more heat from the infrared source200in comparison to the second type of material. In certain embodiments, the material that absorbs relatively more heat may be coated over the material that absorbs relatively less heat.

In certain embodiments, the differences of temperature between different regions of the outside surface of the hot roller400are decreased in comparison to the situation in which identical material is used to coat the inside surface of the hot roller400.

FIG. 5illustrates temperature profiles in an exemplary hot roller102before and after painting different regions of the exemplary hot roller102, in accordance with certain embodiments.

The graph500shown inFIG. 5, indicates the temperature profile310before painting the different regions of the hot roller102, and the temperature profile504after painting the different regions of the hot roller102. It can be seen that the temperature difference504after painting the different regions of the hot roller102is less than the temperature difference312before painting the different regions of the hot roller102.

Therefore,FIG. 5illustrates certain embodiments in which after coating with black paint a plurality of regions on the inside surface of the hot roller102, the differences of temperature between different regions of the hot roller102are decreased in comparison to the differences of temperature between the different regions of the hot roller102before the coating of the plurality of regions.

FIG. 6illustrates a flowchart for determining which regions of the hot roller102to paint, in accordance with certain embodiments.

Control starts at block600, wherein the temperature profile310on the surface of a hot roller102is determined along the longitudinal axis of the hot roller102. Subsequently, a determination (at block602) is made as to whether the difference between the highest and the lowest temperature exceeds a threshold. For example, in certain exemplary embodiments the threshold may be a predetermined number of degrees of Celsius and a determination is made as to whether the maximum temperature difference312exceeds the predetermined number of degrees of Celsius.

If at block602, it is determined that the difference between the highest and the lowest temperature exceeds the threshold, then control proceeds to block604, where repeated determinations are made of the regions of the hot roller102in which the temperatures are relatively lower in comparison to other regions and the determined regions are modified to absorb a greater amount of heat from the infrared source200. The determined regions may be modified by painting the determined regions with black paint. The temperature profile across the surface of the modified hot roller is determined (at block606) and control returns to block602.

If at block602, it is determined that the difference between the highest and the lowest temperature in the temperature profile on the surface of the hot roller does not exceed the threshold, then the process exits (at block608) because the hot roller that is under consideration in block602has a relatively uniform temperature profile whose maximum temperature difference does not exceed the threshold.

FIG. 7illustrates an exemplary hot roller700having a first edge702and a second edge704, where the inside surface of the hot roller700has a first region706, a second region708, and a third region710, in accordance with certain embodiments. In certain embodiments, the hot roller700in additional to the inside surface has an outside surface, and there is a heating element, also referred to as an infrared source, within the hot roller700. The first region706of the inside surface is coated with a first type of material, the second region708of the inside surface is also coated with the first type of material, wherein second region is of a different dimension than the first region. The third region of the inside surface is coated with a second type of material, wherein the second type of material absorbs less heat from the heating element in comparison to the first type of material. In certain embodiments, the first type of material is black paint, and the second type of material is aluminum.

In certain embodiments, the dimensions of the first region706, the second region708, and the third region710are determined based on temperatures profiles measured on the outside surface of the hot roller700. In further embodiments, the entire inside surface is coated with the second type of material, and the first type of material is coated over the second type of material on the first region706and second region708of the inside surface. In additional embodiments, the first region706and the second region708are located adjacent to the two edges702,704of the hot roller700.

In certain embodiments, the hot roller700is included in a first laser printer, wherein in the first laser printer the differences of temperature between different regions of the outside surface of the hot roller700is decreased in comparison to a second laser printer in which identical material is used to coat the inside surface of the hot roller.

Certain embodiments do not use heating elements which can be distributed across the roller to increase the heat delivered to the edge of the roller. Certain embodiments may be used in printing system having an existing lamp design or standard lamps where it is not possible to distribute the heating elements. In addition certain embodiments may be used in situations where it may not be possible to locate and distribute heating filaments within a hot roller to produce proper temperature for fusing toner to hot roller. Furthermore, in certain printing systems the paper width may be narrower than the hot roller and the associated heating elements. In such printing systems, the temperature can be too high at one end of the hot roller, and a coating pattern as described in certain embodiments can cause the temperature to become more uniform.

It has been observed experimentally the two edges706,708of the hot roller102have a lower temperature in comparison to other regions of the hot roller102, and one of the reasons may be exposure to air along the two edges706,708of the hot roller102.

At least certain of the operations illustrated inFIG. 6may be performed in parallel as well as sequentially. In alternative embodiments, certain of the operations may be performed in a different order, modified or removed.

Furthermore, many of the components have been described in separate modules for purposes of illustration. Such components may be integrated into a fewer number of components or divided into a larger number of components. Additionally, certain operations described as performed by a specific component may be performed by other components.

The structures and components shown or referred to inFIGS. 1-7are described as having specific types of information and function. In alternative embodiments, the data structures and components may be structured differently and have fewer, more or different fields or different functions than those shown or referred to in the figures.

Therefore, the foregoing description of the embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Many modifications and variations are possible in light of the above teaching.