Patent Application
20070045270
The present invention relates to establishing temperatures in an image forming apparatus. The image forming apparatus may include printers, including laser or electrophotographic printers and inkjet printers, copiers, faxes, all-in-one devices, or multifunctional devices.
An imaging apparatus, such as a printer, copier, fax machine, all-in-one device or a multifunctional device may include an image fixing device to fix a developing agent, such as toner, to media. The image fixing device may include a heating device such as a fuser. The fuser may have a heat source and a number of rollers or a belt and a roller that may form a nip for the media to pass through. The heat source and the rollers and/or belt may provide heat and/or pressure to the toner that may soften the toner so that the toner may adhere to the media. Improper control of temperature may lead to print defects such as low grade fusing defects, hot offset defects or paper stalls.
The present invention is directed at managing the temperature in an image forming apparatus. For example, the present invention is directed to a method and apparatus relating to the thermal management of an image fixing device such as controlling the temperature of a component that engages with the image fixing device in the image forming apparatus.
Features and advantages of the present invention are set forth herein by description of embodiments consistent with the present invention, which description should be considered in conjunction with the accompanying drawings, wherein:
a and 3b provide a flow chart of an exemplary embodiment of the present invention.
The present invention relates to the management of temperature in an image fixing device. For example, the present invention provides an article and method for the thermal management of a heating device in an image forming apparatus. An exemplary embodiment of an image forming apparatus may include printers, including laser or electrophotographic printers and inkjet printers, copiers, faxes, all-in-one device, or multifunctional devices.
Covering the polymeric layer 118 may be an additional layer or sleeve 120. The additional layer 120 may incorporate low energy material such as polytetrafluoroethylene (PTFE), perfluoroalkoxytetrafluoroethylene, fluorinated ethylene propylene (FEP), fluoroelastomers and other fluoropolymers and combinations of fluoropolymers and other materials. The pressure roller 112 may be driven by a motor M in communication with the pressure roller 112.
The heating device 122 may include a number of components. For example, the heating device may include a heater substrate 124, which may include one or more segments. The substrate may be composed of ceramic material. Furthermore the substrate may be electrically insulative, have a high thermal conductivity, a high heat resistance and/or a low thermal capacity. The heating device may also include one or more heat-generating electrical resistors 126. The resistors may extend along the length of the substrate 124. A temperature detecting element 128 may be included in the heating device 122. The temperature detecting element 128 may include a thermistor or a thermostat. The temperature detecting element 128 may be mounted in contact with the substrate member 124 and in one embodiment may be mounted on a surface of the substrate member 124 opposite an electrical resistor 126.
The heating device may communicate with a processor C. The processor may be a microprocessor or other processor located within the printing device or within the fixing device 122. The heating device may be fixed to a holder 130. A thin layer of electrical insulation such as glass (not shown) may cover the electrical resistors 126. A belt or film 132 may surround the heating device 122.
In one embodiment, the belt 132 may be an idling belt as the belt may be rotated by the pressure roller 112. The belt 132 may be composed of a relatively high heat resistant and durable material such as polyimide. The belt 132 may also be an endless tube and may be between 40-100 microns in thickness. The belt 132 may also include an outer layer (not illustrated) incorporating a relatively low surface energy material such as polytetrafluoroethylene (PTFE), perfluoroalkoxytetrafluroethylene, fluorinated ethylene propylene (FEP), fluoroelastomers and other fluoropolymers and combinations of fluoropolymers and other materials.
As alluded to above, the media P may pass from the developer, where a developing agent such as toner may be deposited, to the fixing device. Prior to fixing, the toner Ta may be loose on the media P. The toner and media may enter the nip (N) between the heating device 122 and the pressure roller 112. The belt 132 may be an idling belt, driven by contact with the pressure roller 112 or alternatively may be driven by driving members, such as motor M. For example, the pressure roller 112 may contact the belt 132 with about 5-20 kilograms of force. Once the media enters the nip N, the toner may be heated and may fuse to the media P, exiting the nip N in a fused state Tc.
In one embodiment the processor C, may be capable of interacting with an image fixing device including a heating device and a pressure or back-up roller. The processor may include software, hardware or firmware. When a print job is generated, the processor may recognize that there may be a print job to be printed and may also recognize the type or properties of print job.
A print job as referred to herein may be considered information or images, such as text, characters or graphics that may be printed on at least one sheet of media. Individual pages of a print job may be referred to as a print page. Properties of a print job may relate to the types of media chosen for printing, the size of the media, the type of developing agent used in the print job, the number of sheets or pages, etc. For example, a print job or a print page in a print job may be a simplex or duplex print job. A simplex may be referred to herein where images may be printed on only one side of the media. A duplex may be referred to herein where images may be printed on both sides of the media.
The processor may also communicate with a temperature detecting element 128, illustrated in
Furthermore, the processor may be capable of interacting with the heating device 122 to set or adjust the heating device temperature. The heating device temperature may be set or adjusted according to another source of information, such as the type of media chosen, the image forming substance used, the speed at which the media may pass through the heating device, the pressure that may be applied to the media during heating, etc. As the heating device, which may be a fuser, and which may include a belt, may be in proximity to the pressure roller, and may contact the pressure roller directly or indirectly (such as when media passes through the nip), adjusting the heating device temperature may directly affect the pressure roller temperature.
It should be appreciated that as the pressure roller may be composed of a polymeric material, such as an elastomeric or rubber material, the pressure roller may retain a portion of the heat energy transferred to the pressure roller from the heating device. This may be the case when one employs polymeric material which may have a relatively low thermal conductivity. Once media begins to feed through the nip, the media may begin to absorb some of the heat otherwise retained in the pressure roller and the pressure roller temperature may partially decrease. However, the pressure roller may retain an excess amount of heat in certain printing situations. The excess heat may cause, e.g., hot offset defects or papers stalls that may result from the generation of steam caused by vaporization of water (e.g., steam) out of the media.
For example purposes only, if a user were to print several short print jobs with relatively small pauses between jobs, the heating device may turn off and cool during the pause and may be forced to ramp back to the printing temperature (without media in the nip) for the next job. Each time the heating device ramps more energy is put into the pressure roller and there may be less opportunity to transfer that energy to the media and there may be a build-up in energy (heat) in the pressure roller. Such repeated ramping to higher printing temperature may cause the temperature in the pressure roller to rise to some undesirable level.
By way another non-limiting example, in the case of duplex printing, a time gap may exist between heating the front and back side of the media. The heating device may be turned off during such gap, which then may require that the heating device must ramp to a printing temperature for heating the back side. As a consequence, when the heating device ramps more energy may then be put into the pressure roller and again there may be less opportunity to transfer that energy to the media. This then may provide another exemplary case of build-up of energy (heat) in the pressure roller and the ramping of the heating device may again cause the temperature in the pressure roller to rise to detrimental levels.
Returning then to the description of the processor, it should be noted that the processor is capable of maintaining a page count. The page count may be referred to herein as the number of print pages that may have been printed in a print job, or the number of print pages that may have been printed in a number of print jobs printed in succession (i.e. a running total). At the start of a print job, the processor may clear the page count and increment the page count for every page printed. However, there may be cases where a number of print jobs have been printed in succession and the page count may not be cleared between the print jobs.
The processor may be further capable of determining whether the motors communicating with the media feeding device M were running when a print job was received. If the motor was still running, it may be possible to skip the step of determining the heating device temperature as one assumption may be made that the heating device is warm.
In one exemplary of the present invention heating device temperature may be regulated and/or the pressure roller temperature may be established based on one or a combination of factors. Such factors may include the heating device temperature prior to printing or at the beginning of a print job, the count of pages that have been printed already, whether the page to be printed may be simplex or duplex or whether the motors for feeding and/or transferring are still running.
The processor may therefore utilize a number of look up tables. The look-up tables may also correlate to the above described factors as well as the aspects of the printing device, such as media throughput. For example, where it is determined that the heating device is beginning from a cold start, the heating device may use temperatures from a first table, e.g., a cold-start look up table, that may be relatively high and allow for the pressure roller to heat up. Alternatively, where it is determined that the heating device is beginning from a cold start but more than a predetermined number of pages have already been printed, cooler heating device temperatures may be used as the pressure roller may already be relatively warm.
When it is determined that the heating device is beginning from a warm start, the heating device may use temperatures from a second table, e.g., a warm-start look up table that may then keep the pressure roller from overheating. Furthermore, if it is determined that the heating device is beginning from a warm start but there is a low page count, the heating device may be set to warmer temperatures.
It should be appreciated therefore, that as referred to herein, the cold-start look up table may include relatively warmer temperatures than the warm-start look up table under comparative conditions of printing. Furthermore, it should be appreciated that there may be more than two look up tables. For example, where a number of heating device states may be identified and printing may start from a number of modes such as cold start, warm start, hot start, etc. or cold start, warm up start, hot start, standby start or power save start.
Illustrated in
The processor may then increment the page count by 1 at 220; however, it should be appreciated that the page count may be incremented at any point in the process. Furthermore, if it has been determined at 211 that the motor have not been turned off, then the process of determining heating device temperature may be skipped and the page count may be incremented directly at 220. A determination whether the page print is a simplex or a duplex may be made at 222. If the page is a duplex, then path A may be followed continuing on
For a duplex, illustrated in
For a simplex page, referring to
The foregoing description is provided to illustrate and explain the present invention. However, the description hereinabove should not be considered to limit the scope of the invention set forth in the claims appended here to.
