JP2007079188A - Fixing device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make shortening of restoration time from a standby state and energy saving compatible for even a user highly frequently using paper sheets other than ordinary paper sheets, by providing standby temperature conditions corresponding to paper type and paper thickness. <P>SOLUTION: A wait timer is turned on after the end of an image forming operation to wait for a time arbitrarily determined by discriminating presence/no presence of a print order, and a fixing temperature target is changed to T0-X in accordance with an elapsed time to reduce the temperature. In the case of the presence of a print order, fixing mode data are acquired, and the fixing mode of the print order is changed in accordance with the data, and the fixing temperature target is set to T0, and the completion of preparations for fixing is determined when the detection value of a fixing temperature reaches T0. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus using the same.

<Standby temperature control>
Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a visible image is formed on a recording paper or the like through a process of charging-exposure (optical writing) -development-transfer-fixing. Among such image forming apparatuses, an image forming apparatus having a heat fixing roller has a problem that power consumption increases because the fixing roller is always heated by a heater or the like when the apparatus is turned on. . Therefore, in order to save energy, there is provided a control device for a copying machine in which a standby temperature is provided as a control value of the surface temperature of the heat fixing roller, and the transition control is performed to this standby temperature after a predetermined time from the end of the image forming process. Proposed.

  However, in the case of this technique, it is necessary to return from the standby temperature to the fixing temperature at which image formation is possible after receiving a print order, and the first copy time becomes long.

  To solve this problem, a plurality of setting values such as a first standby temperature slightly lower than the fixing temperature at the time of the image forming process and a second standby temperature that is significantly lower are provided, for example, a timer for monitoring the time from the latest print order. It has a function, and if there is no print order for a certain arbitrary time, it shifts to the first standby temperature, and if there is no print order longer than that, it shifts to the second standby temperature. A technology has been proposed that provides energy saving means in accordance with the use form while asking the frequency of use by the user so that the higher the is, the faster the transition to the fixing temperature at which image formation is possible.

  In addition, a calendar / clock function is provided that indicates the time and day of the week. Based on the day / time of the user's working hours and other day / time of day information provided in advance, Means such as changing the transition time have also been proposed.

<Fixing temperature variable control according to paper type and paper thickness information>
In the image forming apparatus, in addition to normal plain paper, thick paper, OHP paper, a second original drawing, or the like may be used as paper. Such a difference in paper type affects transferability, fixability, and the like. For example, in an electrophotographic image forming apparatus, the transfer bias and fixing temperature are changed depending on the paper thickness, and the corresponding means and image forming speed are changed. A means for changing (approximately the same as the paper conveyance speed) is provided so that more paper types can be accommodated.
Japanese Unexamined Patent Publication No. 60-169877

  Regarding the means for variably controlling the fixing temperature in accordance with the above-described paper type information, in a high-speed printing machine, lowering the image forming speed results in a decrease in printing performance. Therefore, generally, the transfer bias and the fixing temperature are changed. Means are used.

  In this case, in the return from the standby temperature to the fixing temperature at which image formation is possible and the fixing temperature change at the time of changing the paper type, the fixing temperature is changed instantaneously unlike the change of the bias value as in the transfer condition. However, the temperature adjustment (change) control is performed by the on / off operation control of the fixing heater and the motor, and a certain amount of time (waiting time) occurs.

  The recovery of the fixing temperature from the standby temperature state is triggered by receiving an instruction on the operation display (such as pressing the copy start button) or receiving print order data via the network. The difference from the possible temperature affects the recovery time.

  For example, for users who use extremely thin paper, the fixing temperature is lowered for each operation, and it can be said that excessive energy is constantly consumed.

  Therefore, the present invention provides a fixing device capable of changing and adjusting the standby temperature setting based on the user's setting conditions and usage conditions to eliminate waste of time and energy, and an image forming apparatus using the same. Objective.

  The fixing device according to claim 1 of the present invention includes a control unit that performs standby temperature control for shifting the fixing temperature to a value lower than the temperature at the time of normal image formation when a print order is not given for an arbitrary period of time. Paper condition setting means for presetting the paper type or paper thickness condition for the transfer paper to be stored and fed in the paper stage, and fixing temperature corresponding to the paper type or paper thickness condition set by the paper condition setting means is provided. In the fixing device which can have a plurality, the control unit can set a plurality of standby temperatures corresponding to a plurality of fixing temperatures corresponding to a paper type or a paper thickness condition set by the paper condition setting unit. To do.

  According to a second aspect of the present invention, in the fixing device according to the first aspect of the present invention, the fixing device includes a paper feed stage designating unit that preliminarily designates a paper feed stage to be used preferentially among the paper feed stages. When there is a designation by the stage designation means, the control means sets the standby temperature to a standby temperature corresponding to the paper type or paper thickness of the paper feed stage designated by priority.

  According to the third aspect of the present invention, in the fixing device according to the first or second aspect, the paper condition setting means can preliminarily designate a paper type or a paper thickness to be used, and the paper condition When designated by the setting means, the control means sets the standby temperature to a standby temperature corresponding to the designated paper type or paper thickness.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the sheet passing number history storage unit stores a sheet passing number history for each of the paper feed stages, The control means selects the standby temperature based on the sheet passing history stored in the sheet passing history storage.

  According to the fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the sheet feeding history storage unit for each temperature for storing the sheet passing history for each fixing temperature is provided, and the control unit Is characterized in that the standby temperature is selected based on the history stored in the temperature-specific paper passing history storage means.

  An image forming apparatus according to a sixth aspect of the present invention uses the fixing device according to any one of the first to fifth aspects.

  The present invention makes it possible to achieve both a reduction in the return time from the standby state and energy saving even for a user who frequently uses paper other than plain paper by giving the standby temperature condition to the paper type and paper thickness. To do.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal front view schematically showing an overall configuration of a full-color image forming apparatus to be an object of the present invention. The image forming apparatus 100 of this example is a tandem (parallel type) full-color image forming apparatus using an electrophotographic method, and an image forming unit (printer engine) 300 serving as an image forming unit is arranged at the center of the apparatus body. A paper feeding unit 200 serving as a paper feeding device is disposed immediately below. The paper feed unit 200 is provided with, for example, four stages of paper feed cassettes 21a to 21d each serving as a paper storage unit. These paper feed cassettes 21 a to 21 d are provided so as to be able to be drawn out and stored in the front-rear direction (in the drawing, the front and back sides of the drawing) with respect to the apparatus main body of the image forming apparatus 100. A reading unit (scanner) 400 for reading a document image is disposed above the printer engine 300. Further, a paper discharge tray 8 for discharging paper on which images have been formed is provided on the downstream side (left side in the drawing) of the printer engine 300 in the paper conveyance direction. A manual feed tray 6 serving as a paper storage unit for manually feeding paper is provided on the upstream side (on the right side in the drawing) of the printer engine 300 in the paper conveyance direction.

  In the printer engine 300, four operations for yellow (Y), cyan (C), magenta (M), and black (K) are provided above the intermediate transfer belt 30 that is an endless belt constituting the paper transfer unit 5. Image units are juxtaposed. In each image forming unit, an electrophotographic process member or unit such as a charging unit, an optical writing unit, a developing unit, or a cleaning unit is disposed along the outer periphery of the drum-shaped photoreceptors 1Y to 1K provided for each color. ing.

  Although detailed illustration is omitted, the charging unit performs a charging process on the surfaces of the photoconductors 1Y to 1K, and irradiates the photoconductor surface with laser light from the optical writing unit. The electrostatic latent image formed by exposure on the surface of the photosensitive member is visualized by the developing unit, and toner remaining on the surface of the photosensitive members 1Y to 1K is removed and collected after transfer by the cleaning unit. Then, each color image is sequentially formed on the intermediate transfer belt 30 and the four color images are superimposed on the intermediate transfer belt 30 to form one color image. At that time, first, Y toner is developed by the Y image forming unit and transferred to the intermediate transfer belt 30. Next, in the C image forming unit, C toner is developed and transferred to the intermediate transfer belt 30, then M toner is finally developed and transferred, and K toner is developed and transferred. An image is formed. The four-color toner image transferred onto the intermediate transfer belt 30 is transferred to the transfer paper fed from the paper feed unit 200 by the paper transfer unit 5, fixed by the fixing unit, and then discharged by the paper discharge roller. The paper is discharged to the paper discharge tray 8. On the other hand, after the full-color toner image is transferred, the toner remaining on the surface of the intermediate transfer belt 30 is removed and collected by the belt cleaning unit.

  The paper feed unit 200 includes the above-described four-stage paper feed cassettes 21a to 21d that stack and hold transfer paper set by the user. The paper size and paper type set in each of the paper feed cassettes 21a to 21d is the user himself / herself. Can be set. Further, the conditions of the paper feed cassettes 21a to 21d are determined by automatically judging the paper size, paper type or paper thickness from the side fence position where the transfer papers in the paper feed cassettes 21a to 21d are aligned and the resistance measurement device for the loaded paper. You can also have a means to set automatically. The paper feed cassettes 21 a to 21 d, the manual feed tray 6 and the registration rollers 11 are connected by a conveyance path 12, and transfer paper fed from an arbitrary paper supply location passes through the conveyance path 12 to register rollers. 11 is conveyed. The transfer of the transfer paper is temporarily stopped by the registration roller 11, and the transfer paper is sent to the paper transfer section at a timing so that the positional relationship between the toner image on the intermediate transfer belt 30 and the leading edge of the transfer paper becomes a predetermined positional relationship. . The registration roller 11 functions in the same manner for the transfer paper conveyed from the manual feed tray 6.

  Although detailed illustration is also omitted, in the scanner 400, a plurality of traveling bodies mounted with a light source for illuminating a document and a mirror reciprocate in order to read and scan the document placed on the contact glass 401. The image information scanned by this traveling body is condensed on the imaging surface of the CCD installed behind by the lens and is read as an image signal by the CCD. The read image signal is digitized and subjected to image processing. Then, based on the image-processed signal, optical writing is performed on the surface of the photosensitive member by light emission of the laser diode LD in the optical writing unit, and an electrostatic latent image is formed. The optical signal from the LD reaches the photoconductor via a polygon mirror and a lens. In addition, an automatic document feeder that automatically conveys the document onto the contact glass is mounted on the upper portion of the scanner.

  FIG. 2 is a diagram showing the configuration of the fixing device according to the embodiment of the present invention. The fixing device 7 includes a fixing roller 50 as a fixing member, a heating roller 60, a pressure roller 70, and a fixing belt 40 stretched over the fixing roller 50 and the heating roller 60.

  The fixing roller 50 is rotationally driven by a motor 90, and the heating roller 60, the pressure roller 70, and the fixing belt 40 are driven by rotationally driving the fixing roller 50. Each roller 50, 60, 70 is provided with temperature sensors 53, 63, 73 for detecting the surface temperature thereof, and each of the rollers 50, 60, 70 has a heat source 55, 65, 66, 75. Is placed. Further, the outputs of the temperature sensors 53, 63 and 73 are input to the control means 80, and the control means 80 controls the motor 90 and the heat sources 55, 65, 66 and 75.

  The fixing roller 50 includes a cored bar 51 inside and is covered with a covering material 52. In this example, a heat source (heater) 55 is provided in the metal core 51. The covering material 52 is made of an elastic body such as rubber having a fluororesin layer on the outermost layer. On the other hand, the heating roller 60 includes a metal core 61 having heaters 65 and 66 disposed therein. The fixing belt 40 stretched between the fixing roller 50 and the heating roller 60 has a silicon film disposed on a metal film (for example, Ni, SUS, etc.) or a resin film (for example, PI, PAI) base material, and a surface layer. It is configured by providing a fluororesin.

  In addition, the pressure roller 70 that rotates in pressure contact with the fixing roller 50 with the fixing belt 40 interposed therebetween is configured such that a cored bar 71 is provided inside and a periphery thereof is covered with a covering material 72, similarly to the fixing roller. In this example, a heat source (heater) 75 is provided in the metal core 71. Moreover, the coating | covering material 72 is comprised with elastic bodies, such as rubber | gum which provided the fluororesin layer in the outermost layer.

  In this example, the control unit 80 determines the temperature detected by the temperature sensors 53, 63, 73 and the drive timing of the apparatus for the heaters 55, 65, 66, 75 in the fixing roller 50, the heating roller 60, and the pressure roller 70. Based on the lighting control.

  The sheet to which the toner is attached is pressed under heating of the fixing roller 50 and the fixing belt 40 at a nip portion N formed by the contact between the fixing materials 50 and 72 of the fixing roller 50 and the pressure roller 70 and being deformed. It is fixed. In the above example, the heater is provided in both the fixing roller 50 and the pressure roller 70, but the heater may be disposed only in either the fixing roller 50 or the pressure roller 70.

  Note that the full-color image forming apparatus of the present embodiment is not limited to the function as a so-called digital full-color copier, which scans an original by optical scanning and digitizes and copies it onto a sheet as described above. This is a multifunction device (MFP = multifunction printer) having a function. An image formed by any function is formed by the same image forming process as described above.

  Although not shown, the control system of the apparatus according to the present embodiment mainly includes a system control unit, an image input unit, an image processing unit, a storage unit, a paper feeding unit, a writing unit, a printer engine, a fixing unit, and an operation display unit. Has been. The system control unit has a microcomputer configuration including at least a CPU, a ROM, and a RAM. The CPU controls the above-described units and the whole while using the RAM as a work area in accordance with a program stored in the ROM. The RAM also stores various data used by the CPU during the processing.

  Image data for instructing image formation is input to the image input unit via the scanner 400 or a network. The image data input from the scanner 400 is subjected to image processing by the printer engine 300 and then stored in the storage unit or directly subjected to optical writing exposure from the optical writing unit. As described above, the printer engine 300 performs an image forming process of optical writing, development, transfer, and fixing, and outputs an image.

  The operation display unit has a function of allowing a user to input desired image conditions, number of copies, paper processing, paper type, and the like, and is provided on the main body of the color image forming apparatus, for example, the upper part of the casing of the printer engine 300. In addition to the key input device, the operation display unit is equipped with a touch panel type input device, and various displays including a display of setting conditions input by the liquid crystal display device behind the touch panel and a warning display when the setting conditions are not met. Is done.

  In this embodiment, two stages of setting of the first standby temperature and the second standby temperature are prepared as standby temperature control means for the purpose of energy saving during the idle period (when there is no print order). It has a timer function to monitor the time from the end of the latest print order operation, and the last print in preparation for the next print order that may continue for 1 minute after all image forming operations of the given print order are completed Continue to wait at the same fixing temperature as the order (continuous standby period). 5 minutes after the end, the first standby temperature is transferred (first standby period), and 30 minutes after the end, the second standby temperature is transferred (second standby period). When a print order is received during each waiting period, the apparatus first waits without changing the temperature during the continuous waiting period or the first waiting period, and shifts to the previous first waiting temperature during the second waiting period. As soon as the paper type or paper thickness information, which is a condition related to the fixing temperature setting, is obtained from this print order, the paper type or paper thickness is transferred to the fixing temperature and the image forming operation is started. For example, in the case where a print order is given on the operation display unit as in the case of the copier function, and the paper type or paper thickness condition is also obtained, there is almost no above-mentioned first waiting period, and the instructed fixing immediately. It will shift to temperature.

  Next, image formation control according to the paper type or paper thickness will be described. In each of the paper feed cassettes 21 a to 21 d and the manual feed tray 6, the paper size is automatically recognized from the setting of the side fence for aligning the transfer paper to be stored, and each paper type setting is performed by the user in the operation display unit and stored in the storage unit. Stored. This setting can also be displayed and confirmed on the operation display unit, and can also be confirmed on a PC via a network. As for the paper type, it is assumed that OHP is used in addition to plain paper, and the paper thickness is thin paper (including the second original drawing), plain paper, and thick paper, and the user selects each of them.

  As for the paper transfer bias, since the application method to the bias roller is constant voltage control, one specified value is given without depending on the paper type (paper thickness, correctly the volume resistance of the paper). However, the configuration of the paper transfer unit having a correction coefficient for correcting the environmental dependency of the transfer capability and applying a value obtained by multiplying the specified value by the correction coefficient based on the environment is the same as that of the intermediate transfer belt 50. A bias is applied to the counter roller disposed on the inner side of the belt, and repulsive constant current control is performed in which a current value flowing to the paper transfer conveyance roller via the belt + transfer paper is constant.

Regarding the fixing temperature (heating roller temperature) of the fixing device 7, set values according to the paper type and paper thickness are prepared.
Thin paper: 105 ° C
Plain paper: 155 ° C
Cardboard: 175 ° C
OHP: 185 ° C
A control example in which a plurality of standby temperatures are provided corresponding to each of a plurality of fixing temperatures corresponding to a paper type or a paper thickness condition will be described. In this case, the first standby temperature is set to −30 ° C. with respect to each of the fixing temperature prescribed values described above, and the second standby temperature is set to −60 ° C. with respect to each of the above-described fixed fixing temperature prescribed values. A standby temperature is prepared corresponding to the fixing temperature.

  As shown in FIG. 3, first, after completion of the image forming operation, the standby timer is turned on (standby time t) (step 1), the presence / absence of a print order is determined, and an arbitrarily determined time (in this case 5). Minutes) (steps 2 and 3), after a predetermined time has elapsed, the fixing temperature target is changed to “T0-X” (step 4: FIG. 4 is a diagram showing a list of fixing modes), and further a print order. (Steps 5 and 6), the fixing temperature target is changed to “T0-Y” after a predetermined time (Step 7), and further, It is determined whether there is a print order (step 8). If it is determined that there is a print order in each of the determination steps 2, 5, and 8, the standby time t of the standby timer is reset (step 9), and it is determined whether or not the fixing mode data is set (step 10). If the fixing mode is not set, the fixing temperature target is set to “T0-X” (step 11), and it waits until the fixing mode is set (steps 10 and 11). If the fixing mode is set, the fixing of the print order is performed. The mode is changed accordingly, and the fixing temperature target is set to “T0” (step 12). When the detection value of the fixing temperature becomes “T0”, the control 80 (or image formation) is completed. Control system).

  FIG. 5 is a diagram illustrating an example of the return operation from the standby temperature after passing the thick paper to the thick paper mode. A line EX1 in the figure is an example of the present invention having a standby temperature for each fixing temperature, and a line EX2 in the figure shows an operation example in the prior art having only one standby temperature.

  FIG. 6 is a diagram illustrating an example of the return operation from the standby temperature after passing the thin paper to the thin paper mode. A line EX3 in the figure is an example of the present invention having a standby temperature for each fixing temperature, and a line EX4 in the figure shows an operation example in the prior art having only one standby temperature.

  FIG. 7 shows that a paper tray to be preferentially used is prepared as a condition that can be set in advance on the operation display unit by the user. When this priority paper tray is set, the paper size of a given print order is set. The flow of the operation of the embodiment when there are a plurality of paper feed trays that match is shown. In this example, the float of FIG. 3 is different from the float of FIG. 3 only in that it is changed to the fixing mode of the priority paper feed tray in Step 4, and there are a plurality of paper feed trays that match the paper size of the print order. If there is a priority paper feed tray, the paper is fed from that paper feed tray. Then, standby fixing temperature control corresponding to the fixing temperature at the paper type or paper thickness of the priority paper feeding tray is performed.

  In addition, as a condition that can be set in advance on the operation display unit by the user, a paper type and a paper thickness to be preferentially used are prepared. When the priority paper type and the paper thickness are set, a given print order is set. The operation of the embodiment in the case where there are a plurality of paper feed trays that match the paper size of the paper is different in that it is changed to the priority paper type or paper thickness fixing mode in step 4 of FIG. If there is a priority paper type or paper thickness in a plurality of paper feed trays, paper is fed from that paper feed tray. Then, standby fixing temperature control corresponding to the fixing temperature for this priority paper type or paper thickness is performed.

  In addition, there is a sheet count counter for each paper feed tray, and when performing standby fixing temperature control corresponding to the fixing temperature at the paper type or paper thickness of the paper feed tray with the maximum counter value, However, the only difference is that in step 4 of FIG. 7, the counter value is changed to the fixing mode with the paper type or paper thickness of the maximum paper feed tray.

  Further, in the case of having a sheet passing number counter for each paper type or paper thickness and performing standby fixing temperature control corresponding to the fixing temperature at the paper type or paper thickness with the maximum counter value, step 4 in FIG. However, the only difference is that the fixing mode is changed to the paper type or paper thickness of the paper feed tray having the maximum counter value.

  In each of the embodiments described above, the above counter can be reset by the user at a timing when the individual user, user group, usage pattern, etc. will change. In addition, for example, when the power is turned off / on, when the tray setting is changed, the calendar function can be used to automatically reset every month.

  In other words, in the present invention, by providing a standby temperature for each of a plurality of fixing temperatures, it is possible to achieve both a reduction in the recovery time from the standby temperature and energy saving, and the paper type of the priority paper feed stage set by the user. By setting the standby temperature based on the conditions, it is possible to realize energy saving optimized for the user's preference.Furthermore, the standby temperature is set based on the paper passing history for each paper feed stage and the paper passing history for each paper type. In order to make a selection, it is possible to provide a standby temperature tailored to the usage pattern of the user.

1 is a longitudinal front view schematically showing the overall configuration of a full-color image forming apparatus that is an object of the present invention. 1 is a diagram illustrating a configuration of a fixing device according to an embodiment of the present invention. FIG. 3 is a flowchart showing an example of fixing control according to the embodiment of the present invention. Figure showing a list of fixing modes The figure which shows the return operation example to the thick paper mode from the standby temperature after the thick paper passing The figure which shows the return operation example from the standby temperature after thin paper passing to thin paper mode FIG. 6 is a flowchart showing fixing control examples according to Embodiments 2 to 5 of the present invention.

Explanation of symbols

1Y to 1K photoconductor 5 paper transfer unit 6 manual feed tray 7 fixing device 8 paper discharge tray 11 registration roller 12 transport path 21a to 21d paper feed cassette 30 intermediate transfer belt 40 fixing belt 50 fixing roller 53, 63, 73 temperature sensor 55, 65, 66, 75 Heat source 60 Heating roller 70 Pressure roller 80 Control means 90 Motor 100 Image forming apparatus 200 Paper feed unit 300 Image forming unit (printer engine)
400 Reading unit (scanner)
401 Contact glass

Claims (6)

When a print order is not given for an arbitrary period of time, control means for performing standby temperature control for shifting the fixing temperature to a value lower than the temperature at the time of normal image formation, and transfer paper stored and fed in each paper feed stage In a fixing device that has paper condition setting means for presetting paper type or paper thickness condition, and can have a plurality of fixing temperatures corresponding to the paper type or paper thickness condition set by the paper condition setting means, the control means includes: A fixing device, wherein a plurality of standby temperatures can be set corresponding to each of a plurality of fixing temperatures corresponding to a paper type or a paper thickness condition set by the paper condition setting means. The fixing device according to claim 1, further comprising: a paper feed stage designating unit that preliminarily designates a paper feed stage to be used preferentially among the paper feed stages, and when there is a designation by the paper feed stage designation unit, The control means sets the standby temperature to a standby temperature corresponding to the paper type or paper thickness of the paper feed tray designated with priority. 3. The fixing device according to claim 1, wherein the paper condition setting unit can preliminarily specify a paper type or a paper thickness to be used preferentially, and the control is performed when there is a designation by the paper condition setting unit. The fixing device sets the standby temperature to a standby temperature corresponding to the designated paper type or paper thickness. 4. The fixing device according to claim 1, further comprising a sheet passing number history storing unit that stores a sheet passing number history for each of the paper feed stages, and the control unit includes the sheet passing number history. A fixing device, wherein a standby temperature is selected based on a sheet passing number history stored in a storage unit. 5. The fixing device according to claim 1, further comprising: a sheet passing history storage unit for each temperature for storing a sheet passing history for each fixing temperature, wherein the control unit stores the sheet passing history for each temperature. A fixing device that selects a standby temperature based on a history stored in the means. An image forming apparatus using the fixing device according to claim 1.