JP6015121B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a laser printer provided with a fixing device that heats and fixes a toner image transferred onto a recording medium.

  Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, an image forming method for forming a visible image on recording paper through each process of charging → exposure (optical writing) → development → transfer → fixing Has been taken. Among such image forming apparatuses, in an image forming apparatus having a heat fixing roller, the fixing roller is always heated by a heater or the like even when printing processing is not being performed, and enters a standby state in preparation for printing. It is common to be.

  Therefore, there is a problem that the power consumption increases during the standby state in which the fixing roller is heated, and it is necessary to return from the standby fixing temperature to the fixing temperature at which image formation is possible after receiving a print order. There is a problem that the first copy time becomes long.

  With respect to these problems, Patent Document 1 relates to a fixing device and an image forming apparatus using the fixing device, and presets a paper feed tray, a paper thickness, and a paper type to be used preferentially by a user, and a standby temperature according to the preset. And a technique for recording a sheet passing history for each sheet feeding tray and for each fixing temperature and determining a fixing standby temperature based on the data.

  However, in the invention according to Patent Document 1, it takes time and effort for the user himself / herself to set the paper feed tray, paper type and paper thickness condition to be preferentially used in the standby temperature control. In a situation where the image forming apparatus is used, the image forming apparatus is not always used in accordance with the history data. Therefore, the set standby temperature is not necessarily appropriate and may become inefficient.

  Therefore, an object of the present invention is to provide an image forming apparatus including an efficient fixing device that can be set to a more appropriate standby temperature even when used by an unspecified number of users.

  In order to solve the above problems, the image forming apparatus of the present invention shifts 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 a plurality of paper feed trays and for an arbitrary time. Control means for performing standby temperature control; paper condition setting means for presetting paper type or paper thickness condition for transfer paper stored and fed into a plurality of paper feed trays; and paper type set by the paper condition setting means An image forming apparatus having a fixing unit that can have a plurality of fixing temperatures and standby temperatures corresponding to a paper thickness condition, and the control unit includes a plurality of transfer trays with different fixing temperatures in a plurality of paper feed trays, The standby temperature is controlled according to the transfer paper having a low fixing temperature.

  In order to solve the above problems, the image forming apparatus of the present invention shifts 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 a plurality of paper feed trays and for an arbitrary time. Control means for performing standby temperature control; paper condition setting means for presetting paper type or paper thickness condition for transfer paper stored and fed into a plurality of paper feed trays; and paper type set by the paper condition setting means An image forming apparatus having a fixing unit that can have a plurality of fixing temperatures and standby temperatures corresponding to a paper thickness condition, and the control unit includes a plurality of transfer trays with different fixing temperatures in a plurality of paper feed trays, The standby temperature is controlled based on the average value of the fixing temperature of the transfer paper.

  According to the present invention, it is possible to provide an image forming apparatus including an efficient fixing device that can be set to a more appropriate standby temperature even when used by an unspecified number of users.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a configuration of a fixing device provided in an image forming apparatus according to an exemplary embodiment of the present invention. It is a graph which shows the time which transfers to different fixed temperature from different standby temperature. FIG. 5 is a diagram illustrating an example of a fixing temperature and a standby temperature of each sheet with respect to standby temperature control according to the first embodiment of the present invention. FIG. 10 is a diagram illustrating an example of fixing temperatures and standby temperatures of each sheet and an average value of standby temperatures regarding standby temperature control according to the second embodiment of the present invention. It is a figure which shows the example of fixing temperature of each sheet | seat, standby temperature, and weight regarding control of the standby temperature of 3rd Embodiment of this invention. It is a figure which shows the example of the fixing temperature of each paper, standby temperature, weight, basic weight, paper size, and estimated number of sheets regarding control of the standby temperature of 4th Embodiment of this invention.

  The overall configuration of the image forming apparatus 1 according to the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal front view schematically showing the overall configuration of the image forming apparatus 1 of the present embodiment. An image forming apparatus 1 according to the present embodiment is a tandem (parallel type) full-color image forming apparatus using an electrophotographic method, and a printer engine (image forming unit) 2 serving as an image forming unit is provided at the center of the apparatus body. A sheet feeding unit 3 serving as a sheet feeding device is disposed immediately below.

  The paper feed unit 3 is provided with, for example, four stages of paper feed trays 3a to 3d each serving as a paper storage unit. These paper feed trays 3a to 3d are provided so as to be drawn out and housed in the front-rear direction (in the drawing, the front and back sides of the drawing) with respect to the main body of the image forming apparatus 1. A scanner 4 for reading a document image is disposed above the printer engine 2. Further, a paper discharge tray 8 for discharging paper on which images have been formed is provided downstream of the printer engine 2 in the paper conveyance direction (left side in the drawing).

  Note that a manual feed tray 6 that is a paper storage unit for manually feeding paper is provided on the upstream side (right side in the drawing) of the printer engine 2 in the paper conveyance direction. In the printer engine 2, four operations for yellow (Y), cyan (C), magenta (M), and black (K) are provided above an intermediate transfer belt 21 that is an endless belt constituting the paper transfer unit 20. Image units are juxtaposed.

  In each image forming unit, an electrophotographic process member (process unit) 30 such as a charging unit, an optical writing unit, a developing unit, and a cleaning unit is provided along the outer periphery of the drum-shaped photoreceptors 31Y to 31K provided for each color. Is arranged.

  Although detailed illustration is omitted, the charging unit performs a charging process on the surfaces of the photoconductors 31Y to 31K, and irradiates the image surface with laser light from the optical writing unit. The electrostatic latent image formed by exposure on the surface of the photoconductor is visualized by the developing unit, and the toner remaining on the surfaces of the photoconductors 31Y to 31K after transfer is removed and collected by the cleaning unit. Then, each color image is sequentially formed on the intermediate transfer belt 21, and the four color images are superimposed on the intermediate transfer belt 21 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 21. Next, the C toner is developed and transferred to the intermediate transfer belt 21 by the C image forming unit, then the M toner is finally developed and transferred, and the K toner is developed and transferred. An image is formed.

  The four-color toner image transferred onto the intermediate transfer belt 21 is transferred to the transfer paper fed from the paper feed unit 3 by the paper transfer unit 20, fixed by the fixing device 7, and then discharged from the paper discharge roller. 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 21 is removed and collected by the belt cleaning unit. Details of the fixing device 7 will be described later.

  The paper feed unit 3 includes the above-described four-stage paper feed trays 3a to 3d for storing transfer paper set by the user, and the user sets the paper size and paper type to be set in each of the paper feed trays 3a to 3d. be able to. It is also possible to have means for automatically determining the paper size from the side fence position where the transfer papers in the paper feed trays 3a to 3d are aligned and automatically setting the conditions for the paper feed trays 3a to 3d.

  Each of the paper feed trays 3 a to 3 d, the manual feed tray 6 and the registration roller 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 21 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.

  Next, although detailed illustration is omitted, in the scanner 4, a plurality of traveling bodies mounted with a document illumination light source and a mirror reciprocate in order to read and scan a document placed on the contact glass 40. . 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 9, and an electrostatic latent image is formed. The optical signal from the LD reaches the photoconductor via a polygon mirror and a lens. An automatic document feeder 5 that automatically feeds a document onto the contact glass 40 is mounted on the upper portion of the scanner 4.

  The configuration of the fixing device 7 according to the image forming apparatus 1 of the embodiment of the present invention will be described below with reference to FIG. The fixing device 7 includes a fixing roller 70 as a fixing member, a heating roller 80, a pressure roller 90, and a fixing belt 100 stretched over the fixing roller 70 and the heating roller 80.

  The fixing roller 70 is rotationally driven by a motor 75, and the heating roller 80, the pressure roller 90, and the fixing belt 100 are driven by rotationally driving the fixing roller 70. Each roller 70, 80, 90 is provided with temperature sensors 73, 82, 93 for detecting the surface temperature thereof, and each of the rollers 70, 80, 90 has a heat source 74, 83, 84, 94. Is placed. Further, the outputs of the temperature sensors 73, 82, 93 are input to the control means 110, and the control means 110 controls the motor 75 and the heat sources 74, 83, 84, 94.

  The fixing roller 70 includes a cored bar 71 inside and is covered with a covering material 72. In this example, a heat source 74 is provided in the cored bar 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.

  The heating roller 80 includes a metal core 81 having heat generation sources 83 and 84 disposed therein. The fixing belt 100 spanned between the fixing roller 70 and the heating roller 80 has a silicon film disposed on a metal film (for example, Ni, SUS, etc.) or a resin film (for example, PI, PAI) substrate, and a surface layer. It is configured by providing a fluororesin.

  In addition, the pressure roller 90 that rotates in pressure contact with the fixing roller 70 with the fixing belt 100 interposed therebetween is configured by including a cored bar 91 inside and covering the periphery thereof with a covering material 92, similarly to the fixing roller 70. In this example, a heat source 94 is provided in the cored bar 91. The covering material 92 is made of an elastic body such as rubber having a fluororesin layer on the outermost layer.

  In the present embodiment, the temperature detected by the temperature sensor 73, 82, 93 by the heat sensor 74, 83, 84, 94 in the fixing roller 70, the heating roller 80, and the pressure roller 90 by the control unit 110 and the driving of the apparatus. Lighting control is performed based on timing.

  The sheet to which the toner is attached is pressed under the heating of the fixing roller 70 and the fixing belt 100 at a nip portion N formed by the contact of the covering materials 72 and 92 of the fixing roller 70 and the pressure roller 90 with pressure. It is fixed. In the above example, the heat source is provided on both the fixing roller 70 and the pressure roller 90. However, the heat source may be disposed only on either the fixing roller 70 or the pressure roller 90.

  In the present embodiment, a plurality of standby temperatures are prepared for the purpose of energy saving during the idle period (no print order). It has a timer function for monitoring the time from the end of the latest print order operation, and after all the image forming operations for a given print order have been completed, it shifts to a standby temperature after an arbitrarily set time. When a print order is received during the waiting time, the paper type or paper thickness is immediately transferred to the fixing temperature and the image forming operation is started.

  Next, image formation control according to the paper type or paper thickness will be described. In each of the paper feed cassettes 3a to 3d 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 on the operation display unit, which is not shown. Stored in the storage unit.

  This setting can also be confirmed on the operation display unit, and can also be confirmed on a monitor provided in a personal computer 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 cardboard, but is not limited thereto. Note that the user can also select the paper type.

  Regarding the fixing temperature (heating roller temperature) of the fixing device 7, set values according to the paper type and paper thickness are prepared. For example, in the fixing device 7, it is defined that an optimum image can be obtained with 105 ° C. for thin paper, 155 ° C. for plain paper, 175 ° C. for thick paper, 185 ° C. for OHP, etc., and corresponds to the paper type or paper thickness condition. There can be a plurality of standby temperatures corresponding to each of a plurality of fixing temperatures.

  In this embodiment, the standby temperature is set to −30 ° C. with respect to each of the above-described fixing temperature specified values, and the standby temperature is prepared corresponding to the fixing temperature corresponding to each paper type and paper thickness, but is particularly limited. It is not something.

[First Embodiment]
Next, standby temperature control in the image forming apparatus 1 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a graph showing the time required to shift from a different standby temperature to a fixed fixing temperature. Further, it is assumed that sheets of the type shown in FIG. 4 are stored in the sheet feed trays 3a to 3d of the image forming apparatus 1, for example.

  That is, as shown in FIG. 4, plain paper having a fixing temperature of 155 ° C. and a standby temperature of 125 ° C. is stored in the paper feed trays 3a and 3b, and the fixing temperature is 175 ° C. in the standby temperature of the paper feed tray 3c. Is stored at 145 ° C., and thin paper with a fixing temperature of 105 ° C. and a standby temperature of 75 ° C. is stored in the paper feed tray 3d.

  In the prior art, the standby temperature of the fixing device is often determined based on plain paper that is often used. Therefore, no matter what paper is stored in the paper feed tray, the standby temperature is often set to 125 ° C. obtained by subtracting 30 ° C. from the normal paper fixing temperature of 155 ° C.

  However, when a print order for thin paper is entered when the standby temperature is set to 125 ° C., it is necessary to lower the temperature from the standby temperature of 125 ° C. to 105 ° C., which is the fixing temperature of the thin paper. In this case, energy consumed during standby is wasted and it takes time until the fixing temperature of the thin paper is lowered.

  As shown in FIG. 3, when the standby temperature that is −30 ° C. with respect to the fixing temperature K0 is K1, and the standby temperature that is + 30 ° C. with respect to the fixing temperature K0 is K2, the transition from K1 to K0 due to heating of the heating element is performed. It can be seen that the transition time t2 from K2 to K0 until the fixing roller 70 cools is longer than the time t1.

  Therefore, when the standby temperature is equal to or higher than the fixing temperature, the waiting time of the user until printing is started increases. In the present embodiment, when a type of paper as shown in the example of FIG. 4 is stored in each paper feed tray, control is performed so as to set a low standby temperature (75 ° C. in the example of FIG. 4). To do. Thereby, wasteful energy consumption during standby and user waiting time can be reduced.

[Second Embodiment]
Next, standby temperature control in the image forming apparatus 1 according to the second embodiment of the present invention will be described with reference to FIG. For example, it is assumed that sheets of the type shown in FIG. 5 are stored in the sheet feeding trays 3a to 3d of the image forming apparatus 1, respectively.

  That is, as shown in FIG. 5, the type of paper stored in each paper feed tray is the same as that in FIG. 4, but here the standby temperature corresponds to the paper type stored in each paper feed tray. Control is performed so as to set the average value of the standby temperature (117.5 ° C. in the example of FIG. 5). As a result, the paper temperature in each paper feed tray can be set to a standby temperature that takes into account the frequency of use, and the transition time from the standby temperature to the fixing temperature of each paper can be minimized. Can do.

[Third Embodiment]
Next, standby temperature control in the image forming apparatus 1 according to the third embodiment of the present invention will be described with reference to FIG. For example, it is assumed that the paper trays 3a to 3d of the image forming apparatus 1 store the respective types of sheets as shown in FIG.

  That is, as shown in FIG. 6, the type of paper stored in each paper feed tray is the same as that in FIG. 4, but here the weight of the paper stored in each paper feed tray is the same as that in each paper tray. It is detected by a detecting means such as a weight detection sensor (not shown) provided in FIG.

  For example, the weight of plain paper stored in the paper feed tray 3a is 500 g, the weight of plain paper stored in the paper feed tray 3b is 1200 g, the weight of thick paper stored in the paper feed tray 3c is 1300 g, and the paper feed tray 3d Assume that the weight of the thin paper stored in is detected as 1000 g.

  At this time, control is performed so that the standby temperature of the fixing device 7 is set to a heavy paper (thick paper 145 ° C. in the example of FIG. 6). In other words, it is presumed that a sheet having a large sheet weight has a large number of sheets, and if the number of sheets stored in the sheet feeding tray is large, it is determined that the use frequency is high. Therefore, the standby temperature is controlled based on the sheet weight. That is.

  In addition, when there are a plurality of heavy sheets among the sheets in the sheet feed tray, control is performed to set the standby temperature to the lowest setting among them. Thereby, it can be set as the standby temperature which considered the usage frequency with respect to the paper type in each paper feed tray.

[Fourth Embodiment]
Next, standby temperature control of the image forming apparatus 1 according to the fourth embodiment of the present invention will be described with reference to FIG. For example, it is assumed that papers of the types shown in FIG. 7 are stored in the paper feed trays 3a to 3d of the image forming apparatus 1, and the basis weight of each paper is input by the user. .

  That is, as shown in FIG. 7, the types of paper stored in each paper feed tray are the same as those in FIG. 4, but here, the basis weight (thickness) and paper size are further included as information on each paper. In addition, the weight of each sheet will be described using an example different from FIG.

For example, plain paper having a basis weight of 80 g / m ² , a paper size of A4 and a weight of 3000 g is stored in the paper feed tray 3a, and a basis weight of 90 g / m ² and a paper size of A3, plain paper with a weight of 4000 g is stored, a paper tray 3c with a basis weight of 156 g / m ² , a paper size with a paper size of A3 and a weight of 12000 g, and a paper tray 3d with a basis weight. There 60 g / m ^2, the paper size is A3, the weight is assumed that thin paper 4000g are stored.

Here, the control means 110 calculates the estimated number of sheets from information on the weight and basis weight of the paper stored in each paper feed tray. The estimated number can be calculated by the following equation.
Estimated number of sheets = paper weight (g) ÷ {basis weight (g / m ² ) × paper area (m ² )} (1)

  From the above equation (1), the estimated number of sheets stored in the sheet feed tray 3a is 601 sheets, the estimated number of sheets stored in the sheet feed tray 3b is 356 sheets, and is stored in the sheet feed tray 3c. The estimated number of sheets is 617, and the estimated number of sheets stored in the sheet feed tray 3d is 588.

  In this embodiment, the standby temperature of the fixing device 7 is set to a sheet with a large estimated number of sheets. However, when sheets with the same standby temperature are set in a plurality of paper feed trays, The estimated number may be calculated by summing up.

  For example, in the example of FIG. 7, the estimated number of thick sheets stored in the sheet feed tray 3c is the largest, 617 sheets, but both sheets stored in the sheet feed trays 3a and 3b have the same fixing temperature and standby temperature. Since it is plain paper, the total number of plain papers is calculated as the total number of plain papers of 957, which is the total of 601 plain papers stored in the paper feed tray 3a and 356 plain papers stored in the paper feed tray 3b. Will be the most common.

  Therefore, in this embodiment, the standby temperature of the fixing device 7 is controlled to plain paper (125 ° C.). Thereby, it can be set as the standby temperature which considered the usage frequency with respect to the paper type in each paper feed tray. In addition, when there are a plurality of sheets having the same estimated number of sheets among the sheets in the sheet feeding tray, the control may be performed so that the standby temperature is set low.

  As described above, the image forming apparatus according to the present embodiment described above shifts 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 a plurality of paper feed trays and for an arbitrary time. Control means for performing standby temperature control; paper condition setting means for presetting paper type or paper thickness condition for transfer paper stored and fed into a plurality of paper feed trays; and paper type set by the paper condition setting means An image forming apparatus having a fixing unit that can have a plurality of fixing temperatures and standby temperatures corresponding to a paper thickness condition, and the control unit includes a plurality of transfer trays with different fixing temperatures in a plurality of paper feed trays, The standby temperature is controlled according to the transfer paper having a low fixing temperature.

  Thereby, the standby temperature can be made lower than the fixing temperature, and the fixing temperature can be prevented from becoming lower than the standby temperature. In other words, the fixing roller generally has a large heat capacity, and the process of lowering the temperature takes more time than the process of raising the temperature, so the waiting time for the user is shortened by setting the standby temperature below the fixing temperature. be able to. Further, excessive energy used during standby can be reduced. In general, it is possible to provide an efficient image forming apparatus that can be set to a more appropriate standby temperature even when used by an unspecified number of users.

  Further, the image forming apparatus according to the present embodiment described above has a plurality of paper feed trays and standby temperature control that shifts 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 time. Control means for performing, paper condition setting means for presetting paper type or paper thickness condition for transfer paper stored and fed in a plurality of paper feed trays, and paper type or paper thickness condition set by the paper condition setting means And a fixing unit capable of having a plurality of fixing temperatures and standby temperatures corresponding to the control unit, and the control unit is configured to transfer transfer sheets having different fixing temperatures in a plurality of paper feed trays. The standby temperature is controlled based on the average fixing temperature.

  As a result, the standby temperature can be set in consideration of the frequency of use for the paper types in each paper feed tray, and the transition time from the standby temperature to the fixing temperature of each paper can be minimized. it can. In addition, excessive energy consumption during standby can be reduced. In general, it is possible to provide an efficient image forming apparatus that can be set to a more appropriate standby temperature even when used by an unspecified number of users.

  The image forming apparatus of the present embodiment described above further includes detection means for detecting the amount of transfer paper stored in the plurality of paper feed trays, and the control means is stored in the plurality of paper feed trays. The standby temperature is controlled in accordance with the largest amount of the transfer paper detected by the detecting means among the transfer paper being detected. The detecting means detects the weight of the transfer paper stored in the plurality of paper feed trays. Thereby, it can be set as the standby temperature according to a user's use frequency with respect to the paper type in each paper feed tray.

  In the image forming apparatus according to the present embodiment described above, the detection unit detects the number of transfer sheets in each sheet feed tray from the information on the weight and thickness of the transfer sheets stored in the plurality of sheet feed trays. . Thereby, it can be set as the standby temperature according to a user's use frequency with respect to the paper type in each paper feed tray.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 7 Fixing apparatus 70 Fixing roller 80 Heating roller 90 Pressure roller 73, 82, 93 Temperature sensor 74, 83, 84, 94 Heat source 75 Motor 110 Control means

Japanese Patent No. 4666294

Claims (5)

Multiple paper trays,
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 when a print order is not given for an arbitrary time;
Paper condition setting means for presetting a paper type or a paper thickness condition for transfer paper stored and fed into the plurality of paper feed trays;
An image forming apparatus having fixing means capable of having a plurality of fixing temperatures and standby temperatures corresponding to the paper type or paper thickness condition set by the paper condition setting means,
The control means controls the standby temperature in accordance with a transfer paper having a low fixing temperature among the transfer papers when transfer papers having different fixing temperatures are contained in the plurality of paper feed trays, respectively. Forming equipment. Multiple paper trays,
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 when a print order is not given for an arbitrary time;
Paper condition setting means for presetting a paper type or a paper thickness condition for transfer paper stored and fed into the plurality of paper feed trays;
An image forming apparatus having fixing means capable of having a plurality of fixing temperatures and standby temperatures corresponding to the paper type or paper thickness condition set by the paper condition setting means,
The control unit controls the standby temperature based on an average value of the fixing temperatures of the transfer sheets when transfer sheets having different fixing temperatures are contained in the plurality of paper feed trays, respectively. apparatus. Detecting means for detecting the amount of transfer paper stored in the plurality of paper feed trays;
When there are a plurality of transfer sheets detected by the detection unit among the transfer sheets stored in the plurality of paper feed trays, the control unit determines the amount of the transfer sheets present. The image forming apparatus according to claim 1, wherein the standby temperature is controlled in accordance with a low fixing temperature among a large number of papers or based on an average value of the fixing temperatures of the transfer paper .   The image forming apparatus according to claim 3, wherein the detection unit detects a weight of the transfer paper stored in the plurality of paper feed trays.   The detection unit detects the number of transfer sheets in the plurality of sheet feed trays from information on the weight and thickness of the transfer sheets stored in the plurality of sheet feed trays. 5. The image forming apparatus according to 4.

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