JP5972682B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a multifunction machine, and a printer.

  This type of image forming apparatus includes a paper feeding device that accommodates paper, prints and forms an image on the paper supplied from the paper feeding device, and discharges the paper. As a paper feeding device, a paper bundle is loaded on a paper stacking table, air is sucked through each air hole of the paper transport belt, and the paper in the paper bundle is sucked and transported to the paper transport belt, or a pick-up roller is attached to the paper. There are things that pull out by pressing against a bundle of paper.

  In such a paper feeding device, when the adhesion between the sheets of the sheet bundle becomes high due to moisture absorption, the uppermost sheet of the sheet bundle and the next sheet are pulled out and the double sheet feeding occurs. There are things to do.

  For this reason, in Patent Document 1, a heater is provided inside the duct, and the air is blown from the opening of the duct to the front end surface of the sheet bundle while the air is heated by the heater as soon as the image forming apparatus is turned on. In addition, the duct is reciprocated in the vertical direction, and the heated air is blown over the entire front end surface of the sheet bundle to reduce the humidity of the sheet bundle.

  In Patent Document 2, a heater is provided inside the duct, air heated by the heater is blown from the opening of the duct to the side end surface of the sheet bundle, and the humidity of the atmosphere is detected by a sensor. The humidity of the sheet bundle is adjusted by changing the temperature and wind speed of the air blown to the side end face of the sheet bundle according to the detected humidity.

  Further, in Patent Document 3, the heater built in the image forming apparatus is turned on when the image forming apparatus is started, the heater temperature is set to a temperature suitable for standard paper, and a paper of a different type from the standard paper is printed. Sometimes, the temperature of the heater is increased according to the paper.

Japanese Patent Laid-Open No. 2004-352381 JP2011-63345A JP-A-6-19361

  By the way, if the adhesiveness between the sheets of the sheet bundle becomes high due to moisture absorption, double feeding of the paper may occur. However, with regard to plain paper, the frequency of occurrence of double feeding is not required even if heating by a heater is not performed. Low. In particular, in a paper feeding device that adsorbs and conveys sheets of a sheet bundle to a sheet conveying belt, air is blown to the end surface of the sheet bundle so that air enters between the sheets of the sheet bundle, and the sheet is conveyed by the sheet conveying belt. Therefore, with regard to plain paper, there is almost no occurrence of double feeding of paper. However, for glossy paper and thick paper, heating with a heater is effective because adhesion between paper sheets tends to be high due to moisture absorption and the frequency of occurrence of double feeding of paper is high.

  However, in Patent Documents 1 and 2, heating by a heater is performed without distinguishing between plain paper, glossy paper, and thick paper, and in Patent Document 3, heating by a heater is performed for standard paper (corresponding to plain paper). In the case of a different type of paper from the standard paper, the temperature of the heater is raised.

  Accordingly, in any of Patent Documents 1 to 3, heating is performed on the plain paper that is difficult to cause double feeding, and power is wasted.

  For this reason, for example, it is conceivable that heating of the paper by the heater is started after an instruction to start printing of the paper is given, thereby saving power and shortening the heating time of the paper. However, in this case, printing cannot be started from the instruction to start printing on the paper until the temperature of the heater has sufficiently increased, and the time for waiting for the user becomes long.

  In addition, when the heating time of the paper becomes long, the surface resistance of the paper becomes uneven, and the surface charge amount of the paper becomes uneven, which causes uneven transfer of the toner image on the paper, resulting in a reduction in image quality. In particular, in the case of glossy paper, such a problem is likely to occur. However, none of the cited documents 1 to 3 considers such a problem that occurs when the heating time of the sheet becomes long.

  Therefore, the present invention has been made in view of the above-described conventional problems, can save power, can shorten the time from the instruction to start printing until the temperature of the heater sufficiently rises, and the paper An object of the present invention is to provide an image forming apparatus in which the heating time is not prolonged.

In order to solve the above-described problems, an image forming apparatus according to the present invention prints an image on a sheet feeding unit that accommodates a sheet, a heater provided in the sheet feeding unit, and a sheet supplied from the sheet feeding unit. An image forming apparatus including a printing unit, a temperature detection unit that detects a temperature related to the paper feeding unit, and a paper input unit that inputs that the paper stored in the paper feeding unit is a predetermined paper And a print execution input unit that inputs start of printing by the printing unit, and when the predetermined paper is input by the paper input unit, the heater is controlled and detected by the temperature detection unit The temperature to be set is set to the first target temperature, and after the fact that the predetermined paper is input , when the execution start of the printing is input by the print execution input unit, the heater is controlled, The temperature detected by the temperature detector is set to the second target temperature. And a control unit for the constant to.

  In the present invention, the temperature related to the paper feed unit is set to the first target temperature only when the paper stored in the paper feed unit is a predetermined paper. For this reason, when the paper stored in the paper supply unit is plain paper, the heater is turned off to save power. When the start of printing is input, the heater is controlled to set the temperature related to the paper feed unit to the second target temperature. Therefore, only when printing is performed, the temperature related to the paper feed unit is raised, and the heating time of the paper in the paper feed unit is not prolonged. In addition, when printing start is input in a state where the temperature related to the paper feed unit is maintained at the first target temperature, the temperature related to the paper feed unit is set to the second target temperature. The time required for the temperature to reach the second target temperature is shortened.

  In the image forming apparatus according to the aspect of the invention, the temperature detection unit includes a first temperature detection unit that detects the temperature of the heater, and a second temperature detection unit that detects the temperature of the paper feed unit, The controller sets the temperature detected by the first temperature detection unit to a first target temperature when the paper input unit inputs that it is the predetermined sheet, and prints by the print execution input unit When the execution start is input, the temperature detected by the second temperature detector is set to the second target temperature.

  As described above, by providing the first temperature detection unit that detects the temperature of the heater and the second temperature detection unit that detects the temperature of the paper feeding unit as the temperature detection unit, temperature control related to the paper feeding unit is performed more accurately. It becomes possible.

  In the image forming apparatus according to the aspect of the invention, for example, the paper input unit is an input operation unit, and the input operation unit indicates that the predetermined operation sheet is stored in the paper supply unit. Is input to the control unit, the fact that it is the predetermined sheet.

  Alternatively, in the image forming apparatus of the present invention, for example, the paper input unit is an input operation unit, and the input operation unit is configured such that the paper supply unit in which the predetermined paper is stored is operated by the input operation unit. Is input to the control section, the fact that the sheet is the predetermined sheet.

  In the image forming apparatus according to the aspect of the invention, for example, the paper input unit is a paper sensor provided in the paper feeding unit, and the paper sensor receives the paper stored in the paper feeding unit as the predetermined value. The paper is detected and output to the control unit.

  Furthermore, in the image forming apparatus of the present invention, the predetermined paper is glossy paper or thick paper.

  Glossy paper and thick paper tend to have high adhesion between papers due to moisture absorption, and the frequency of paper multi-feeding increases. Therefore, when the paper stored in the paper supply unit is glossy paper or thick paper, the heater is controlled to set the temperature related to the paper supply unit to the first target temperature, and the start of printing is input. Sometimes, it is preferable to control the heater to set the temperature of the paper feed unit to the second target temperature, and to prevent the double feed by heating glossy paper or cardboard stored in the paper feed unit.

  In the image forming apparatus according to the aspect of the invention, the paper feeding unit sucks the paper in the paper bundle by sucking air, a paper stacking base on which the paper bundle is stacked, an elevating unit that lifts and lowers the paper stacking base. A sheet conveying member that conveys the air and an air duct that blows out air to the end face of the sheet bundle, and the heater is provided inside the air duct.

  In such a configuration, the air inside the air duct is heated by the heater, the heated air is blown onto the sheet bundle, and the sheet bundle is efficiently heated. Further, when air is blown onto the end face of the sheet bundle, air enters between the sheets, and this also makes it difficult for the sheets to be double fed.

  Furthermore, in the image forming apparatus of the present invention, the temperature detection unit detects the temperature of the heater and the temperature of the air blown from the exhaust port of the air duct to the end face of the sheet bundle, and the control unit The temperature of the heater and the temperature of the air detected by the temperature detection unit are set to a first target temperature and a second target temperature, respectively.

  As described above, since the air heated by the heater is blown onto the sheet bundle and the sheet bundle is heated, the heater temperature is set to the first target temperature, and the air temperature is set to the second target temperature. It is preferable to set.

  In the image forming apparatus of the present invention, for example, when the printing executed by the printing unit is completed, the control unit controls the heater to set the temperature detected by the temperature detection unit to a first target. Set the temperature again.

  Furthermore, the image forming apparatus of the present invention includes a humidity detection unit that detects the humidity of the paper feed unit, and the control unit determines whether the humidity detected by the humidity detection unit is greater than or less than a threshold value. The heater is turned off when the humidity is lower than the threshold, and the heater is controlled to set the first and second target temperatures when the humidity is equal to or higher than the threshold.

  When the humidity is low, even for glossy paper or thick paper, the adhesion between the papers is low, and it is difficult for paper to be double fed, so if the humidity is below the threshold, set the heater off, Heating of the paper feeder is stopped. Thereby, further power saving is possible.

  As described above, in the present invention, the temperature related to the paper feeding unit is set to the first target temperature only when the paper stored in the paper feeding unit is a predetermined paper. For this reason, when the paper stored in the paper supply unit is plain paper, the heater is turned off to save power. When the start of printing is input, the heater is controlled to set the temperature related to the paper feed unit to the second target temperature. Therefore, only when printing is performed, the temperature related to the paper feed unit is raised, and the heating time of the paper in the paper feed unit is not prolonged. In addition, when printing start is input in a state where the temperature related to the paper feed unit is maintained at the first target temperature, the temperature related to the paper feed unit is set to the second target temperature. The time required for the temperature to reach the second target temperature is shortened.

1 is a cross-sectional view showing an embodiment of an image forming apparatus of the present invention. FIG. 3 is a perspective view illustrating an appearance of the sheet feeding device as viewed obliquely from above. FIG. 3 is a plan view illustrating a main part of a paper feeding device. FIG. 3 is a front view illustrating a main part of a paper feeding device. FIG. 4 is a perspective view showing the sheet feeding device with the sheet drawer portion removed, as viewed obliquely from the rear. FIG. 3 is a perspective view showing a paper drawer portion of the paper feeding device as viewed obliquely from above and front. It is a perspective view which shows a paper drawer part seeing from back diagonally upward. It is a perspective view which shows a paper drawer part seeing from back diagonally downward. It is sectional drawing which shows a paper feeding apparatus roughly. 2 is a block diagram schematically showing a control system of the image forming apparatus. FIG. 3 is a plan view showing an operation panel of the image forming apparatus. FIG. (A), (b) is a figure which shows the procedure for registering the kind of paper accommodated in the paper feeder on the screen of the display part of the operation panel. FIG. 4 is a diagram conceptually illustrating a data table in which types of sheets stored in a sheet feeding device are registered. It is a figure which shows a reflection type optical sensor roughly. (A), (b) is a figure which shows the procedure for inputting which recording paper is supplied from which of each paper feed cassette and each paper feeder on the screen of the display part of an operation panel. It is a flowchart which shows the control procedure of the heater of the exhaust duct of a paper feeder. A characteristic curve j1 (t) indicating the temperature j1 of the heater detected by the first temperature sensor, a characteristic curve j2 (t) indicating the temperature j2 of the air blown from the exhaust duct detected by the second temperature sensor, It is a timing chart which shows the current characteristic i (t) to be sent.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of the image forming apparatus of the present invention. The image forming apparatus 1 is roughly composed of a printing unit 11, a sheet transport unit 12, a sheet supply unit 13, a large-capacity paper feed cassette (LCC) 14, a document reading device 15, and a document transport device 16. .

  In the printing unit 11, after the residual toner on the surface of the photosensitive drum 21 is removed and collected by the cleaning device 26, the surface of the photosensitive drum 21 is uniformly charged to a predetermined potential by the charging device 22, and then the laser exposure device 23. The surface of the photosensitive drum 21 is exposed to form an electrostatic latent image on the surface, and the developing device 24 develops the electrostatic latent image on the surface of the photosensitive drum 21 to form a toner image on the surface of the photosensitive drum 21. To do.

  The transfer roller 25 is pressed against the photosensitive drum 21 to form a nip area with the photosensitive drum 21, and the recording paper conveyed through the paper conveyance path 33 is sandwiched and conveyed in the nip area. At the same time, the toner image on the surface of the photosensitive drum 21 is transferred onto the recording paper. Then, the recording paper is sandwiched between the heating roller 28 and the pressure roller 29 of the fixing device 27 and heated and pressed to fix the toner image on the recording paper.

  On the other hand, the paper supply unit 13 includes a plurality of paper supply cassettes 38. Each paper feed cassette 38 includes a pickup roller 39 and the like for pulling out and feeding out recording sheets one by one, and sends out the pulled-out recording sheets to the sheet transport path 33 of the sheet transport section 12.

  The large-capacity paper feed cassette (LCC) 14 can store a large amount of recording paper, pulls out the recording paper one by one, and sends it out to the paper transport path 33 of the paper transport section 12.

  The recording sheet is conveyed through a sheet conveying path 33 and is discharged to a sheet discharge tray 37 via a transfer roller 25 and a fixing device 27 and a sheet discharge roller 36. In this paper conveyance path 33, the recording paper is temporarily stopped and the leading edges of the recording paper are aligned, and then the recording paper is fed in accordance with the transfer timing of the toner image in the nip area between the photosensitive drum 21 and the transfer roller 25. A registration roller 32 for starting conveyance, a conveyance roller 31 for urging conveyance of a recording sheet, a sheet discharge roller 36, and the like are arranged.

  Further, when printing not only on the front side of the recording paper but also on the back side, the position of the branch claw 35 is switched, and the recording paper is conveyed in the reverse direction from the paper discharge roller 36 to the reverse path 34, so that the recording paper The front and back sides are reversed, and the recording paper is again guided to the registration roller 32, and an image is recorded and fixed on the back surface of the recording paper in the same manner as the front surface of the recording paper, and the recording paper is discharged to the paper discharge tray 37.

  Next, the document reading device 15 and the document conveying device 16 mounted on the upper part of the main body of the image forming apparatus 1 will be described. The document conveying device 16 is pivotally supported on the back side of the document reading device 15 by a hinge (not shown), and the document conveying device 16 is opened by moving the front portion up and down to open the document reading device. Documents can be placed on the 15 document placement glasses 44.

  In the document reading device 15, the first scanning unit 45 is moved in the sub-scanning direction, and the document on the document placement glass 44 is illuminated by the light source of the first scanning unit 45 while following the second scanning unit 46. The reflected light is reflected by the mirrors of the first and second scanning units 45, 46, and the reflected light is further condensed by the imaging lens 47 and led to a CCD (Charge Coupled Device) 48, and the original image of the original is captured by the CCD 48. Read the image.

  Further, when reading an image on the surface of the document being conveyed by the document conveying device 16, the first scanning unit 45 is moved to a reading position below the document reading glass 55, and the second scanning unit 45 is moved in accordance with the position of the first scanning unit 45. The scanning unit 46 is positioned. In the document transport device 16, the document is drawn from the document tray 57, transported to the document reading glass 55 through the document transport path 58, and the document on the document reading glass 55 is illuminated by the light source of the first scanning unit 45. The reflected light is reflected by the mirrors of the first and second scanning units 45 and 46, and the reflected light is condensed by the imaging lens 47 and guided to the CCD 48. The image of the original is read by the CCD 48, and the original is read. The document is discharged to the document discharge tray 62.

  The original image read by the CCD 48 in this manner is input to the laser exposure device 23 of the image forming apparatus 1, and the image is recorded on the recording paper in the image forming apparatus 1, and this recording paper is output as a copy original.

  Next, the configuration of the paper feeding device 71 built in the large capacity paper feeding cassette 14 will be described in detail. The large-capacity paper feed cassette 14 contains a plurality of paper feed devices 71, all of the paper feed devices 71 having the same configuration, storing a large amount of recording paper, and drawing out the recording paper one by one. Then, the sheet is sent to the sheet conveyance path 33 (shown in FIG. 1) of the image forming apparatus 1.

  FIG. 2 is a perspective view showing the external appearance of the sheet feeding device 71 as viewed obliquely from above. The paper feeding device 71 has a drawer housing 71a, and the main part of the paper feeding device 71 is provided inside the drawer housing 71a. The drawer housing 71a is supported by a well-known mechanism combining rollers and rails (not shown), for example, so as to be reciprocally movable in the arrow directions Ma and Mb within the main body of the large-capacity paper feed cassette 14, so The paper feeding device 71 can be taken in and out of the accommodation space inside the main body of the paper cassette 14. A sheet bundle is replenished and set in the sheet feeding device 71 in a state where the sheet feeding device 71 is pulled out from the accommodation space inside the main body of the large capacity sheet feeding cassette 14. In addition, in a state where the paper feeding device 71 is pushed into the housing space inside the main body of the large capacity paper feeding cassette 14, the paper bundle 71 sequentially draws out the sheets of the paper bundle to the paper transport path 33 of the image forming apparatus 1. And fed.

  3 and 4 are a plan view and a front view showing the sheet feeding device 71, respectively. As shown in FIGS. 3 and 4, the sheet feeding device 71 includes an outer frame 72 (the frame of the drawer housing 71 a shown in FIG. 2), a bottom plate 73, and a paper stacking base 74 disposed inside the outer frame 72. , And a paper drawer 75 disposed on one upper side of the outer frame 72.

  The sheet stacking table 74 is used for stacking a large amount of recording sheets (sheet bundle) and is provided inside the outer frame 72 so as to be moved up and down. The paper stacking base 74 is formed with an opening 74 a that is long in the recording paper drawing direction (paper transport direction) E. The paper trailing edge guide 76 is supported on the bottom plate 73 so as to be reciprocally movable along the recording paper drawing direction E, and protrudes upward through the opening 74 a of the paper stacking table 74. The recording paper drawing direction (paper conveyance direction) E is the front, and the direction opposite to the drawing direction E is the rear.

  Recesses 74b are formed on both sides of the sheet stacking table 74, and assist ducts 77 and 78 are disposed in the respective recesses 74b. The assist ducts 77 and 78 are supported on both sides of the outer frame 72 so as to be able to reciprocate in a direction orthogonal to the drawing direction E, and are moved in conjunction with each other so as to approach each other or to be separated from each other. The

  The paper drawing section 75 includes four endless paper conveyance belts 81, a set of rollers 82 and 83 around which each paper conveyance belt 81 is stretched, an intake / exhaust fan 84, an intake duct 85, an exhaust duct 86, and the like. ing. Each paper transport belt 81 is formed with a large number of air holes 81 a, and air is sucked from the air holes 81 a of each paper transport belt 81 to the intake / exhaust fan 84 through the intake duct 85. Further, the air exhausted from the intake / exhaust fan 84 is guided through the exhaust duct 86 and is blown out from the exhaust duct 86 to the inside of the outer frame body 72 in the direction opposite to the extraction direction E (rearward).

  FIG. 5 is a perspective view showing the outer frame body 72, the bottom plate 73, the paper stacking board 74, and the like viewed obliquely from the rear side with the paper drawer portion 75 removed. As shown in FIG. 5, two protruding pieces 74 c are formed on both sides of the paper stacking table 74, and each protruding piece 74 c protrudes from the opening 72 a on both sides of the outer frame body 72. On one side of the outer frame 72, two wires 87 are connected to the protruding pieces 74 c on one side of the paper stacking base 74, and each wire 87 is hooked around a plurality of driven pulleys 88 and drawn around a take-up pulley 89. It is connected. On the other side of the outer frame 72, the other two wires 87 are connected to the protruding pieces 74c on the other side of the sheet stacking table 74, and the other wires 87 are connected to a plurality of other driven pulleys 88. It is drawn around and connected to another take-up pulley 89. Each winding pulley 89 is fixed to both ends of a common shaft 91 that is rotatably supported. The shaft 91 is rotationally driven by a pulse motor 92 to rotate each winding pulley 89, and each wire 87 is wound to each winding 87. It is wound around the pulley 89 and is fed out from each winding pulley 89.

  When the shaft 91 is rotationally driven by the pulse motor 92 and each take-up pulley 89 is rotated in the clockwise direction, each wire 87 is taken up by each take-up pulley 89, the paper stacking table 74 is raised, and each take-up pulley 89 is also turned up. When the take-up pulley 89 is rotated in the counterclockwise direction, each wire 87 is fed out from each take-up pulley 89, and the sheet stacking table 74 is lowered. Further, the rotation angle of the take-up pulley 89 that is rotationally driven by the pulse motor 92 and the height of the paper stacking base 74 are in a corresponding relationship. Therefore, by controlling the rotation direction and rotation angle of the pulse motor 92, the height of the sheet stacking base 74 can be adjusted and set.

  Further, as shown in FIG. 5, assist fans 79 and 80 are provided outside the assist ducts 77 and 78, respectively. Each of the assist ducts 77 and 78 is a hollow body and has a ventilation path therein. Air sucked by each of the assist fans 79 and 80 is sent to the ventilation paths of the respective assist ducts 77 and 78. The air is blown out to the inside of the outer frame 72 from the blowout ports 77a and 78a of the assist ducts 77 and 78.

  Further, as shown in FIGS. 2, 3, and 5, a contact member 101 is supported on the upper portion of the paper rear end guide 76 so as to be reciprocally rotatable in the arrow rotation directions Qa and Qb. When the paper feeding device 71 is pulled out from the housing space inside the main body of the large-capacity paper feeding cassette 14, the contact member 101 is retracted by rotating in the arrow rotation direction Qa until the contact member 101 becomes substantially vertical. Replenish and set on the loading table 74. When the paper feeding device 71 is pushed into the housing space inside the main body of the large-capacity paper feeding cassette 14, the contact member 101 is rotated in the arrow rotation direction Qb until it is substantially horizontal, and in this state the paper stacking base is moved. 74 is raised to bring the contact member 101 into contact with the rear end portion of the upper surface of the sheet bundle, and the contact member 101 prevents the rear end portion of the recording sheet of the sheet bundle from being lifted.

  Further, a height position sensor (not shown) is provided for detecting the rotational position of the contact member 101 when it is slightly pushed up by contacting the rear end of the upper surface of the sheet bundle. Then, the rotational position of the contact member 101 when it is brought into contact with the rear end of the upper surface of the sheet bundle and slightly pushed up is detected.

  Next, the configuration of the paper drawer 75 will be described in detail. FIG. 6 is a perspective view showing the paper drawer portion 75 as viewed obliquely from the upper front. FIG. 7 is a perspective view showing the paper drawer portion 75 as viewed obliquely from above and rearward, and FIG. 8 is a perspective view of the paper drawer portion 75 as seen from diagonally below and rear.

  As shown in FIGS. 6, 7, and 8, the paper drawing unit 75 includes four endless paper conveyance belts 81, a set of rollers 82 and 83 that bridge the paper conveyance belts 81, an intake / exhaust fan 84, An intake duct 85 and an exhaust duct 86 are provided.

  The intake duct 85 is a hollow body, and has an air suction path that is long in a direction orthogonal to the drawing direction (paper conveyance direction) E, and one end 85 a thereof is connected to the intake / exhaust fan 84. Then, as indicated by an arrow F, air is sucked from the air suction path of the intake duct 85 to the intake port (not shown) of the intake / exhaust fan 84 through the one side end 85a.

  In addition, air suction holes 94 (shown in FIG. 9) are formed on the lower surface 85 g of the air intake duct 85 so as to overlap the plurality of air holes 81 a of the paper transport belt 81 for each paper transport belt 81. Each air suction hole 94 is connected to the air suction path of the intake duct 85. When the air inside the intake duct 85 is sucked by the intake / exhaust fan 84, the outside air passes through the air holes 81a of the paper transport belts 81 and the air suction holes 94 of the lower surface 85g of the air intake duct 85, so Flows into.

  Furthermore, the front end portion 85c and the rear end portion 85d of the intake duct 85 are formed with respective recesses 85h, and the rollers 82 and 83 are disposed in these recesses 85h so as to be rotatably supported. The paper transport belt 81 is bridged between the rollers 82 and 83. Further, the output shaft of the transport motor 93 is connected to the shaft of the front roller 82. The front roller 82 is rotationally driven in the arrow direction D by the transport motor 93, the rear roller 83 is driven to rotate, and each paper transport belt 81 rotates in the arrow direction D.

  The exhaust duct 86 is also a hollow body and has a long ventilation path in a direction orthogonal to the drawing direction E. One end 86a of the exhaust duct 86 is connected to the intake / exhaust fan 84, as indicated by an arrow K. Air is sent from the exhaust port (not shown) of the intake / exhaust fan 84 to the ventilation path of the exhaust duct 86 through the one end 86a of the exhaust duct 86.

  A plurality of exhaust ports 96 communicating with the ventilation path of the exhaust duct 86 are formed on the inner wall surface 86 d of the exhaust duct 86. An inner wall surface 86 d of the exhaust duct 86 is provided so as to overlap with an outer surface of a contact plate 72 b (shown in FIG. 5) of the outer frame body 72, and each exhaust port 96 of the exhaust duct 86 is a contact plate of the outer frame body 72. It faces the inside of the outer frame 72 through the notch 72c of 72b. When air is sent from the intake / exhaust fan 84 to the exhaust duct 86, the air is blown out from the exhaust ports 96 toward the inside of the outer frame 72 (rearward).

  Further, a heater 97 is provided on the inner wall surface of the exhaust duct 86, a first temperature sensor (for example, a thermistor) 98 for detecting the temperature of the heater 97 is attached to the heater 97, and each of the other inner wall surfaces of the exhaust duct 86 is provided. A second temperature sensor 99 that detects the temperature of the air blown from each exhaust port 96 is provided in the vicinity of the exhaust port 96.

  In the sheet feeding device 71 having such a configuration, as shown in the schematic cross-sectional view of FIG. 9, the sheet bundle is placed on the sheet stacking table 74, and the sheet bundle is brought into contact with the sheet rear end guide 76 and the outer frame body 72. Positioning is performed by being sandwiched between the plates 72b, and the sheet bundle is positioned by being sandwiched between the assist ducts 77 and 78. In this state, each take-up pulley 89 is rotated clockwise by the pulse motor 92 to raise the paper stacking table 74 and come into contact with the rear end portion of the upper surface of the sheet bundle and slightly pushed up. When the rotation position is detected by the height position sensor, the pulse motor 92 is stopped, and the uppermost recording sheet of the sheet bundle is positioned at a predetermined suction position Bp.

  Then, air is sent from the assist fans 79 and 80 to the assist ducts 77 and 78, and air is blown from the exhaust ports 77a and 78a of the assist ducts 77 and 78 to both end surfaces of the sheet bundle on the sheet stacking board 74. Then, air is allowed to enter between the recording sheets, and the recording sheets are dispersed. In addition, air is sent from the intake / exhaust fan 84 to the exhaust duct 86, and air is blown from the exhaust ports 96 to the front end surface of the sheet bundle, so that the air enters between the recording sheets and the recording sheets are dispersed. . As a result, the adhesion of the recording sheets in the sheet bundle is reduced, the recording sheets can be easily pulled out from the sheet bundle, and the recording sheets can be pulled out one by one.

  At the same time, air is sucked from the intake duct 85 to the intake / exhaust fan 84, and air is sucked through the air holes 81 a of the paper transport belt 81 and the air suction holes 94 of the lower surface 85 g of the air intake duct 85. The recording paper is sucked and sucked on the surface.

  Further, the rollers 82 are rotated by the conveying motor 93 to rotate the respective paper conveying belts 81 so that the recording paper is drawn in the drawing direction E by the respective paper conveying belts 81 and conveyed to the conveying roller 31 of the image forming apparatus 1. . When the recording sheet is conveyed to the conveyance roller 31, the suction of air by the intake / exhaust fan 84 and the rotation of the rollers 82 and 83 by the conveyance motor 93 are temporarily stopped, and the conveyance roller 31 removes the sheet from the sheet conveyance belt 81. After completing the drawing of the recording paper, the suction of air by the intake / exhaust fan 84 and the rotation of the rollers 82 and 83 by the transport motor 93 are resumed, and the next recording paper is sucked onto the surface of each paper transport belt 81. Then, the recording paper is pulled out in the drawing direction E by each paper transport belt 81 and transported to the transport roller 31, and thereafter the recording paper is repeatedly attracted to the surface of each paper transport belt 81 and recorded by each paper transport belt 81. Pull out the paper and carry it.

  When the upper surface of the sheet bundle is lowered due to repeated drawing of the recording sheets, the pulse motor 92 is rotated until the upper surface of the sheet bundle is detected by the height position sensor, the sheet stacking table 74 is raised, and the sheet bundle is raised. The uppermost recording sheet is raised to a predetermined suction position Bp.

  By the way, in the paper feeding device 71, when the internal humidity becomes high, the adhesion between the recording papers of the paper bundle becomes high due to moisture absorption. In particular, glossy paper and thick paper tend to have high adhesion between recording sheets due to moisture absorption, and are adsorbed on the surface of each paper transport belt 81 while the uppermost recording paper in the paper bundle and the next recording paper are in close contact. , Double feeding of recording paper occurs.

  Therefore, as is well known, it is desirable to heat the sheet bundle to reduce the humidity of the sheet bundle and to reduce the adhesion between the recording sheets of the sheet bundle. However, air is blown to the end face of the sheet bundle so that the air enters between the recording sheets and the sheets are easily adsorbed by the sheet conveying belts 81. Even if it is not, double feeding does not occur.

  Therefore, if not only glossy paper and thick paper but also plain paper that is difficult to cause double feeding is heated, power is wasted. Also, if heating of glossy paper or cardboard is started by the heater after printing on glossy paper or cardboard is instructed, it will take a long time until the temperature of glossy paper or cardboard becomes sufficiently high, and the waiting time will be long. become longer. Further, when the heating time of the sheet bundle is lengthened, unevenness of the surface resistance of the recording sheet occurs, which causes uneven transfer of the toner image on the recording sheet, and the image quality is deteriorated.

  Therefore, in the image forming apparatus 1 of the present embodiment, as shown in FIG. 8, the heater 97 inside the exhaust duct 86 of the sheet feeding device 71, the first temperature sensor 98 that detects the temperature of the heater 97, and the exhaust ports 96. And a second temperature sensor 99 for detecting the temperature of the air blown from the air, and only when glossy paper or cardboard is stored in the paper feeding device 71, the temperature of the heater 97 inside the exhaust duct 86 is set to the first target temperature. After that, when the sheet feeding device 71 is selected and the start of printing is instructed, the temperature of the air blown out from each exhaust port 96 of the exhaust duct 86 to the sheet bundle becomes the second target temperature. Thus, the heater 97 is controlled. Therefore, if glossy paper or thick paper is not stored in the paper feeding device 71, the heater 97 is kept off, and power is not consumed wastefully. Further, when the temperature of the heater 97 is set to the first target temperature, that is, the heater 97 is appropriately heated, and when the paper feeding device 71 is selected and the execution start of printing is instructed, the air is blown out to the sheet bundle. Since the heater 97 is controlled so that the temperature of the air to be set becomes the second target temperature, the temperature of the air quickly rises to the second target temperature, and the waiting time is shortened. Further, since the air heated to the second target temperature is blown onto the sheet bundle only when the sheet is fed from the sheet feeding device 71, the heating time of the sheet bundle is short, and the surface resistance of the recording sheet is not uneven. The toner image is not unevenly transferred to the recording paper, and the image quality is not deteriorated.

  Next, the heating control of such glossy paper or cardboard will be described in detail. First, the configuration of the control system of the image forming apparatus 1 will be described. FIG. 10 is a block diagram schematically showing a control system of the image forming apparatus 1. In FIG. 10, the main control unit 111 integrates the image forming apparatus 1 (printing unit 11, paper transport unit 12, paper supply unit 13, document reading device 15, document transport device 16, large-capacity paper feed cassette 14, etc.). The system is controlled by a CPU, RAM, ROM, various interfaces, and the like.

  The memory 112 is, for example, a hard disk device (HDD), and stores various data and programs. The image processing unit 113 performs various image processes on the image data.

  The heater control unit 114 heats and drives the heater 97 inside the exhaust duct 86 of the paper feeding device 71. The humidity sensor 115 detects the humidity inside the large-capacity paper feed cassette 14. Further, as described above, the first temperature sensor 98 detects the temperature of the heater 97, and the second temperature sensor 99 detects the temperature of the air blown out from each exhaust port 96.

  The operation panel 116 includes a display unit 117 made up of a liquid crystal display device and the like, and an input operation unit 118 made up of a plurality of operation keys and a touch panel overlaid on the screen of the display unit 117. Are displayed on the screen of the display unit 117, and instructions, data, and the like input by the operation of the input operation unit 118 are output to the main control unit 111.

  FIG. 11 is a plan view showing the operation panel 116. As illustrated in FIG. 11, the operation panel 116 includes a display unit 117 and an input operation unit 118. The input operation unit 118 includes a user setting key 121, a start key 122, a numeric keypad 123, etc., a touch panel (not shown) superimposed on the screen of the display unit 117, and the like. When any one of the display buttons (display areas) on the screen of the display unit 117 is operated, the touch panel detects the operated display button. The input operation unit 118 notifies the main control unit 111 of an operated key or a display button (display area) detected by the touch panel. For example, by operating each key or each display button, the type of each recording sheet stored in each sheet feeding device 71 built in each sheet feeding cassette 38 and the large capacity sheet feeding cassette 14 can be input, It is possible to input which of the paper feed cassette 38 and each paper feed device 71 is to supply the recording paper. Alternatively, the start of printing by the printing unit 11 or the like of the image forming apparatus 1 can be input by operating the start key 122.

  In such a configuration, for example, the main control unit 111 causes the document reading device 15 to read an image of the document, stores image data indicating the image of the document in the memory 112, and causes the image processing unit 113 to store the image data in the memory 112. The image data is processed, and the image of the document indicated by the image data in the memory 112 is recorded on the recording paper by the printing unit 11.

  Further, when one of the paper feed cassettes 38 of the paper supply unit 13 is instructed as a recording paper supply source by the operation of the input operation unit 118 and the start of printing is instructed by the operation of the start key 122, a response is received. Then, the main control unit 111 controls the paper feed cassette 38 and supplies recording paper from the paper feed cassette 38 to the printing unit 11.

  Alternatively, when one of the sheet feeding devices 71 of the large-capacity sheet feeding cassette 14 is instructed as a recording paper supply source by the operation of the input operation unit 118 and the start of printing is instructed by the operation of the start key 122, The control unit 111 controls the paper feeding device 71 to supply recording paper from the paper feeding device 71 to the printing unit 11.

  The image forming apparatus 1 is connected to the personal computer PC through the network N, and can send and receive print jobs to and from the printer driver 131 of the personal computer PC. In the image forming apparatus 1, a print job from the personal computer PC is stored in the memory 112 and analyzed by the main control unit 111 or the image processing unit 113, and an image indicated by the image data of the print job is recorded on recording paper by the printing unit 11. Print.

  Next, a procedure for registering glossy paper or thick paper in the paper feeding device 71 will be described. First, the user presses the user setting key 121 on the operation panel 116 shown in FIG. In response to this, the main control unit 111 displays a system setting screen 141 as shown in FIG. 12A on the display unit 117 of the operation panel 116. When the user operates the “paper tray setting” display button 142 on the system setting screen 141, a paper tray setting screen 143 as shown in FIG. 12B is displayed under the control of the main control unit 111. When the user operates the “plain paper / A4” display button 144 corresponding to the paper feeding device 71 on the paper feeding tray setting screen 143, a pop-up screen 145 is displayed under the control of the main control unit 111. . Further, when the user operates the “glossy paper” display button 146 or the “thick paper” display button 147 on the pop-up screen 145, the main control unit 111 controls the glossy paper or thick paper to correspond to the paper feeding device 71. Then, it is registered in the registration data table in the memory 112, and “glossy paper” or “thick paper” is displayed on the display button 144 in the paper feed tray setting screen 143. FIG. 13 illustrates a registration data table. As shown in FIG. 13, in the registration data table DT, the types and sizes of the recording sheets accommodated in the respective paper feed cassettes 38 and the large capacity paper feed cassettes 14 are registered. Has been.

  Note that the size of the recording paper is detected by a sensor (not shown) built in each paper feed cassette 38 and each paper feed device 71 and is automatically registered in the registration data table DT. Alternatively, when the “paper feed tray setting” display button 142 in FIG. 12A is selected and the paper feed tray setting screen 143 or the pop-up screen 145 in FIG. A screen may also be displayed, and the size of the recording paper may be set on this other screen and registered in the registration data table DT. Also, the type of recording paper can be detected by the sensors of each paper feed cassette 38 and each paper feed device 71 and automatically registered in the registration data table DT. For example, a reflection type optical sensor 151 as shown in FIG. 14 is provided at each location Sp facing the surface (recording surface) of the recording paper in each paper feed cassette 38 and each paper feed device 71 in FIG. The reflective optical sensor 151 includes a light emitting element 152 that emits light to the surface of the recording paper P, and a light receiving element 153 that receives light regularly reflected by the surface of the recording paper P. When the recording paper P is glossy paper or thick paper, the light is regularly reflected on the surface of the recording paper P, and when the recording paper P is plain paper, the light is irregularly reflected on the surface of the recording paper P. The amount of light received by the light receiving element 153 varies depending on whether the paper is plain paper. Therefore, it can be determined whether the paper is glossy paper or plain paper based on the amount of light received by the light receiving element 153, and the type of recording paper can be automatically registered in the registration data table DT. Whether or not the recording paper is a thick paper can be detected by a known ultrasonic sensor and automatically registered in the registration data table DT.

  Next, a procedure for inputting which of the paper feeding devices 71 of the paper feeding cassettes 38 and the large capacity paper feeding cassettes 14 is to be supplied will be described. First, the user operates the display area 162 on the standby screen 161 displayed on the display unit 117 of the operation panel 116 as shown in FIG. In response to this, the main control unit 111 displays a paper selection screen 163 as shown in FIG. 15B on the display unit 117 of the operation panel 116. Each display area 165 in the paper selection screen 163 corresponds to each paper feed cassette 38 and each paper feed device 71, and each display area 165 is accommodated in each paper feed cassette 38 and each paper feed device 71. Each recording paper type is displayed. When the display area 165 in which the desired recording paper type is displayed is selected from the display areas 165 and the OK button 166 is designated, in response to this, the main control unit 111 selects the selected display area. The paper feed cassette 38 or the paper feed device 71 corresponding to 165 is selected. When the execution start of printing is input by operating the start key 122 on the operation panel 116, the main control unit 111 responds to this by controlling the selected paper feed cassette 38 or paper feed device 71 and selecting the selected one. The recording paper of the type displayed in the selected display area 165 is supplied from the paper supply cassette 38 or the paper supply device 71 to the printing unit 11, and the printing unit 11 is controlled to supply the image. Print on recording paper.

  Further, in the personal computer PC, when a print job is transferred to the image forming apparatus 1 using the printer driver 131, a desired type of recording paper is stored in the same operation procedure as the operation panel 116. The paper cassette 38 or the paper feeding device 71 can be selected and designated. Here, in addition to the printer driver 131, the personal computer PC is provided with a control unit 132, a display unit 133, an input operation unit (keyboard or mouse) 134, and the like. In such a personal computer PC, a registration data table DT is stored in a memory (not shown) by data communication with the image forming apparatus 1, and a paper selection screen 163 in FIG. Displayed on the section 133. When one of the display areas 165 on the paper selection screen 163 is selected by the operation of the input operation unit 134, the OK button 166 is instructed, and the start of printing is input by the operation of the input operation unit 134. In response to this, the printer driver 131 transfers the print job to the image forming apparatus 1 and instructs the image forming apparatus 1 to start execution of the selected paper feed cassette 38 or paper feed device 71. In response to this, the image forming apparatus 1 supplies the recording paper from the selected paper feeding cassette 38 or the paper feeding device 71 and prints the image indicated by the image data of the print job on the recording paper by the printing unit 11. To do.

  Next, a control procedure of the heater 97 of the exhaust duct 86 of the paper feeding device 71 will be described with reference to the flowchart of FIG. This control procedure is performed for each paper feeding device 71 of the large capacity paper feeding cassette 14.

  First, the main control unit 111 obtains the humidity H inside the large-capacity paper feed cassette 14 detected by the humidity sensor 115 built in the large-capacity paper feed cassette 14 (step S201). Then, the main control unit 111 determines whether or not the humidity H inside the large-capacity paper feed cassette 14 is equal to or higher than a preset threshold value h (for example, 50%) (step S202), and the humidity H is less than the threshold value h. If so ("No" in step S202), the heater 97 is kept off without controlling the heater 97 of the exhaust duct 86 of the paper feeder 71 (step S203). This is because, in an environment where the humidity H is less than the threshold value h, the moisture absorption level of the sheet bundle accommodated in the sheet feeding device 71 is low, and even with glossy paper or thick paper, the adhesion between the recording sheets is low, and recording is performed. This is because there is no paper double feed. Another reason for this is to save power by avoiding turning on the heater 97 wastefully.

  If the humidity H is equal to or higher than the threshold value h (“Yes” in step S202), the main control unit 111 refers to the registered data table DT to determine whether glossy paper or thick paper is stored in the paper feeding device 71. If glossy paper or thick paper is not stored in the paper feeder 71 (“No” in step S204), the heater 97 of the exhaust duct 86 of the paper feeder 71 is not controlled. The heater 97 is kept off (step S203). This also realizes power saving.

  If glossy paper or thick paper is stored in the paper feeding device 71 (“Yes” in step S204), the main control unit 111 controls the heater 97 of the paper feeding device 71 through the heater control unit 114, and the heater 97 Turn on. Then, the main control unit 111 performs on / off control of the heater 97 through the heater control unit 114 so that the temperature j1 of the heater 97 detected by the first temperature sensor 98 becomes the first target temperature (for example, 110 ° C.) J1 (Step S1). S205).

  Here, it is determined at any time whether glossy paper or thick paper is accommodated in the paper feeding device 71 in step S204. For example, when the glossy paper or thick paper is registered in the registration data table DT in association with the paper feeding device 71 in the procedure of FIGS. 12A and 12B during the operation of the image forming apparatus 1, the main control unit. 111, referring to the registration data table DT, determines that glossy paper or thick paper is stored in the paper feeding device 71, and uses the temperature j1 of the heater 97 detected by the first temperature sensor 98 as the first target temperature J1. Set to. Alternatively, when the reflection type optical sensor 151 in FIG. 14 or a known ultrasonic sensor detects that the recording paper of the paper feeding device 71 is glossy paper or thick paper, the main control unit 111 performs reflection at this detection time. Based on the detection output of the mold optical sensor 151 or a known ultrasonic sensor, it is determined that glossy paper or thick paper is stored in the paper feeding device 71, and the temperature j1 of the heater 97 detected by the first temperature sensor 98 is set to the first temperature sensor 98. 1 Set to target temperature J1.

  Even when the image forming apparatus 1 is activated, the main control unit 11 refers to the registration data table DT and determines that glossy paper or thick paper is stored in the paper feeding device 71 by the first temperature sensor 98. The detected temperature j1 of the heater 97 is set to the first target temperature J1. Alternatively, when the image forming apparatus 1 is activated, if the reflective optical sensor 151 of FIG. 14 or a known ultrasonic sensor detects that the recording paper of the paper feeding device 71 is glossy paper or thick paper, the main control unit 111. Determines that glossy paper or thick paper is accommodated in the paper feeding device 71 and sets the temperature j1 of the heater 97 detected by the first temperature sensor 98 to the first target temperature J1.

  Of course, when the glossy paper or cardboard registered in the registration data table DT is changed or deleted, or when the glossy paper or cardboard is no longer detected by the reflective optical sensor 151 or a known ultrasonic sensor, the heater 97 is turned off. Switch.

  In this way, with the temperature j1 of the heater 97 maintained at the first target temperature J1, the paper feeding device 71 containing glossy paper or cardboard in the procedure of FIGS. 15A and 15B is the recording paper supply source. The start of printing is input by operating the start key 122 of the operation panel 116, or a print job is transferred from the personal computer PC, and the paper feeding device 71 containing glossy paper or cardboard is accommodated. When the start of printing is instructed (“Yes” in step S206), the main control unit 111 first responds to the second temperature sensor provided in the vicinity of each exhaust port 96 of the exhaust duct 86. The temperature j2 detected at 99 is taken in and stored in the memory 112 as the temperature j20 (step S207). Since the second temperature sensor 99 is provided in the vicinity of each exhaust port 96 on the inner wall surface of the exhaust duct 86, the sheet is fed by the second temperature sensor 99 when air is not blown out from each exhaust port 96. The temperature (atmosphere temperature) inside the device 71 is detected. Accordingly, the temperature j20 in the memory 112 is the ambient temperature inside the sheet feeding device 71.

  Subsequently, the main control unit 111 drives the assist fans 79 and 80 and the exhaust fan 84 of the sheet feeding device 71 as described above to send air from the exhaust ports 77a and 78a of the assist ducts 77 and 78, respectively. Air is blown to both end faces of the sheet bundle, and air is blown from the exhaust ports 96 of the exhaust duct 86 to the front end face of the sheet bundle. In addition, air is sucked from the intake duct 85 to the intake / exhaust fan 84 to adsorb the uppermost recording sheet of the sheet bundle to the surface of each sheet conveying belt 81.

  At the same time, the main control unit 111 adds a preset temperature (for example, 25 ° C.) to the ambient temperature j20 in the memory 112 to obtain the second target temperature J2, and controls the heater 97 on and off through the heater control unit 114. Then, the temperature j2 detected by the second temperature sensor 99 is adjusted and set to the second target temperature J2 (step S208). As a result, air heated to the second target temperature J2 is blown from each exhaust port 96 of the exhaust duct 86 to the leading end surface of the sheet bundle.

  Then, when the temperature j2 detected by the second temperature sensor 99 reaches the second target temperature J2, the main control unit 111 drives and controls the transport motor 93 to move each paper transport belt 81 around and move each paper. The drawing and conveyance of the recording paper by the conveyance belt 81 are started.

  Here, when the air heated to the second target temperature J2 is blown onto the front end surface of the sheet bundle, each recording sheet of the sheet bundle is heated, and the adhesion between the recording sheets is effectively reduced, Air reliably enters between the recording sheets, and the recording sheets vary well. For this reason, even if the recording paper is pulled out and conveyed by each paper conveying belt 81, the recording paper is not double-fed.

  The second target temperature J2 is maintained as long as the recording paper supply from the paper feeding device 71 continues ("No" in step S209). When the supply of the recording paper from the paper feeding device 71 is completed (“Yes” in step S209), the main control unit 111 stops the assist fans 79 and 80 and the exhaust fan 84, and each paper transport belt 81 is also turned on. The heater 97 is stopped, the heater 97 is turned on / off through the heater control unit 114, and the temperature j1 of the heater 97 is returned to the first target temperature J1 and set again (step S205).

  Accordingly, glossy paper or thick paper is stored in the paper feeding device 71, and glossy paper or thick paper is registered in the registration data table DT in association with the paper feeding device 71, or the reflective optical sensor 151 of the paper feeding device 71 or the like. When glossy paper or thick paper is detected by a known ultrasonic sensor, on / off control of the heater 97 of the paper feeding device 71 is started, and the temperature j1 of the heater 97 detected by the first temperature sensor 98 is the first target. The temperature is adjusted and maintained at J1 (for example, 110 ° C.). After that, when the paper feeding device 71 is selected as the recording paper supply source and the start of printing is instructed, the second temperature sensor is detected at the time of this instruction. 99 is obtained as the ambient temperature j20 inside the sheet feeding device 71, and the second target temperature J2 (for example, ambient temperature j20 + 25 ° C.) is obtained based on the ambient temperature j20. It is set. Then, the blowing of air from each exhaust port 96 of the exhaust duct 86 to the front end surface of the sheet bundle is started, the heater 97 is controlled to be turned on / off, and the temperature j2 of the air blown from each exhaust port 96 is set to the second target. When the temperature J2 is adjusted to be equal to the temperature J2 and the air temperature j2 reaches the second target temperature J2, the drawing and conveyance of the recording sheet by each sheet conveyance belt 81 are started.

  FIG. 17 shows a characteristic curve j1 (t) indicating the temperature j1 of the heater 97 detected by the first temperature sensor 98, a characteristic curve j2 (t) indicating the temperature j2 of the air detected by the second temperature sensor 99, and the heater 97 is a timing chart showing a current characteristic i (t) that flows through 97.

  As shown in the timing chart of FIG. 17, glossy paper or thick paper is stored in the paper feeding device 71, and glossy paper or thick paper is registered in the registration data table DT in association with the paper feeding device 71, or the paper feeding device 71. On / off control of the heater 97 is started at time t0 when glossy paper or thick paper is detected by the reflective optical sensor 151 or a known ultrasonic sensor, and the temperature j1 of the heater 97 detected by the first temperature sensor 98 at time t1. Reaches the first target temperature J1 and is maintained. When the paper feeding device 71 is selected as a recording paper supply source and an instruction to start printing is instructed, the temperature j2 of the air detected by the second temperature sensor 99 at the time point t2 of this instruction is the paper feeding device. 71, the second target temperature J2 is set based on the ambient temperature j20, the heater 97 is turned on / off, and the temperature j2 of the air blown out from each exhaust port 96 is set to the second target temperature. The supply of glossy paper or thick paper from the paper feeding device 71 is started at time t3 when the temperature of the air j2 reaches the second target temperature J2.

  As described above, in the present embodiment, glossy paper or thick paper is stored in the paper feeding device 71, and glossy paper or thick paper is registered in the registration data table DT in association with the paper feeding device 71 or in the paper feeding device 71. When glossy paper or thick paper is detected by the reflective optical sensor 151 or a known ultrasonic sensor, the temperature j1 of the heater 97 is adjusted and set to the first target temperature J1, and the paper feeding device 71 supplies the recording paper. When the start of printing is selected and the heater 97 is controlled so that the temperature j2 of the air blown out to the sheet bundle becomes the second target temperature J2, when the start of printing is input, The temperature j2 quickly rises to the second target temperature J2, and the waiting time after the start of printing is input is shortened. In addition, air heated to the second target temperature J2 is blown onto the sheet bundle only when glossy paper or thick paper is supplied from the sheet feeding device 71, so the heating time of the sheet bundle is short and the surface resistance of the recording sheet is reduced. No unevenness occurs, toner image transfer unevenness with respect to the recording paper does not occur, and image quality does not deteriorate. If glossy paper or thick paper is not stored in the paper feeding device 71, the heater 97 is kept off, so that power is not wasted.

  In the above embodiment, when glossy paper or thick paper is registered in the registration data table DT in association with the paper feeding device 71, or by using the reflective optical sensor 151 in FIG. 14 or a known ultrasonic sensor. When it is detected that the recording paper 71 is glossy paper or thick paper, the temperature j1 of the heater 97 detected by the first temperature sensor 98 is set to the first target temperature J1, but instead, The temperature j1 of the heater 97 detected by the first temperature sensor 98 is selected as the first target temperature J1 when the paper feeding device 71 containing glossy paper or thick paper is selected before the start of printing is instructed. May be set. Also in this case, the heater 97 is controlled so that the temperature j2 of the air blown out to the sheet bundle becomes the second target temperature J2 when the start of printing is input.

  Further, although the paper feeding device 71 is illustrated as an application target of the present invention, the present invention can also be applied to the paper feeding cassette 38.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Printing part 12 Paper conveyance part 13 Paper supply part 14 Large capacity paper feed cassette (LCC)
15 Document reader 16 Document transport device 33 Paper transport path 71 Paper feed device 72 Outer frame 73 Bottom plate 74 Paper stacking base 75 Paper drawer portion 76 Paper rear end guide 77, 78 Assist duct 79, 80 Assist fan 81 Paper transport belt 82 83 Roller 84 Intake / exhaust fan 85 Intake duct 86 Exhaust duct (air duct)
92 Pulse motor 93 Conveyance motor 94 Air suction hole 96 Exhaust port 97 Heater 98 First temperature sensor (first temperature detector)
99 Second temperature sensor (second temperature detector)
111 Main control unit (control unit)
114 Heater control unit 115 Humidity sensor (humidity detection unit)
116 Operation panel 117 Display unit 118 Input operation unit (paper input unit, print execution input unit)
151 Reflective optical sensor (paper input unit, paper sensor)

Claims (11)

An image forming apparatus comprising: a paper feeding unit that stores paper; a heater provided in the paper feeding unit; and a printing unit that prints an image on the paper supplied from the paper feeding unit.
A temperature detecting unit for detecting a temperature related to the paper feeding unit;
A paper input unit for inputting that the paper stored in the paper supply unit is a predetermined paper;
A print execution input unit for inputting start of printing by the printing unit;
When the predetermined paper is input by the paper input unit, the heater is controlled to set the temperature detected by the temperature detection unit to the first target temperature, and the predetermined paper is When the start of printing is input by the print execution input unit after the input is input, a control unit that controls the heater and sets the temperature detected by the temperature detection unit to a second target temperature; An image forming apparatus comprising: The image forming apparatus according to claim 1,
The second target temperature is higher than the first target temperature
An image forming apparatus. The image forming apparatus according to claim 1 , wherein:
The temperature detection unit includes a first temperature detection unit that detects the temperature of the heater, and a second temperature detection unit that detects the temperature of the paper feed unit,
The controller sets the temperature detected by the first temperature detection unit to a first target temperature when the paper input unit inputs that it is the predetermined sheet, and prints by the print execution input unit When the execution start is input, the temperature detected by the second temperature detection unit is set to a second target temperature. An image forming apparatus according to any one of claims 1 to 3 , wherein
The paper input unit is an input operation unit,
The input operation unit outputs, to the control unit, the predetermined sheet when the input operation unit inputs that the predetermined sheet is stored in the sheet feeding unit. An image forming apparatus. An image forming apparatus according to any one of claims 1 to 3 , wherein
The paper input unit is an input operation unit,
The input operation unit is configured to output to the control unit that the predetermined sheet is received when the sheet feeding unit that stores the predetermined sheet is input by an operation of the input operation unit. Image forming apparatus. An image forming apparatus according to any one of claims 1 to 3 , wherein
The paper input unit is a paper sensor provided in the paper feeding unit,
The image forming apparatus, wherein the sheet sensor detects that a sheet stored in the sheet feeding unit is the predetermined sheet and outputs the detected sheet to the control unit. An image forming apparatus according to any one of claims 1 to 6 , wherein
The image forming apparatus, wherein the predetermined sheet is glossy paper or thick paper. An image forming apparatus according to any one of claims 1 to 7 ,
The sheet feeding unit includes a sheet stacking table for stacking a sheet bundle, an elevating unit for moving the sheet stacking table up and down, a sheet conveying member that adsorbs and conveys the sheets of the sheet bundle by suction of air, and air An air duct that blows out to the end face of the stack of paper,
The image forming apparatus, wherein the heater is provided inside the air duct. The image forming apparatus according to claim 8 , wherein
The temperature detection unit detects the temperature of the heater and the temperature of air blown from the exhaust port of the air duct to the end face of the sheet bundle,
The image forming apparatus, wherein the control unit sets the temperature of the heater and the temperature of the air detected by the temperature detection unit to a first target temperature and a second target temperature, respectively. An image forming apparatus according to any one of claims 1 to 9 , wherein
When the printing executed by the printing unit is completed, the control unit controls the heater to reset the temperature detected by the temperature detection unit to a first target temperature again. . An image forming apparatus according to any one of claims 1 to 10 , wherein
A humidity detector for detecting the humidity of the paper feed unit;
The control unit determines whether the humidity detected by the humidity detection unit is equal to or higher than a threshold value, and sets the heater to off when the humidity is lower than the threshold value, and the humidity is equal to or higher than the threshold value. In this case, the image forming apparatus controls the heater for setting the first and second target temperatures.

Images