JP2007193109A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform consecutive printing of small-size recording paper so that unevenness in the temperature distribution of a fixing roller may be eliminated without reducing printing efficiency. <P>SOLUTION: A setting part for setting the number of consecutively printed sheets 11 sets the number of consecutively printed sheets according to the total number of sheets of small-size recording paper to be printed consecutively. A conveyance interval setting part 12 sets the conveyance interval of the small-size recording paper by referring to a conveyance interval determination table 151 and specifying ppm predetermined for the number of consecutively printed sheets set by the setting part for setting the number of consecutively printed sheets 11. The conveyance interval determination table 151 stores the maximum ppm out of ppm enabling the temperature distribution of the fixing roller to be made uniform. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a facsimile, a network printer, and a digital multifunction peripheral.

  2. Description of the Related Art Conventionally, an image forming apparatus that fixes a toner image by heating a recording paper on which a toner image is formed by a fixing roller is known. The fixing roller used in such an image forming apparatus absorbs heat by the recording paper when contacting the recording paper. Therefore, when printing a recording sheet having a large size in the width direction orthogonal to the conveyance direction of the recording sheet, the fixing roller temperature distribution is uniform because almost the entire area of the fixing roller is in contact with the recording sheet. .

  However, when printing a recording paper having a small size smaller than the large size in the width direction, the fixing roller has a region that does not come into contact with the recording paper, so the temperature distribution is not uniform. That is, the temperature of the area not in contact with the recording paper is higher than the temperature of the area in contact.

Therefore, in Patent Document 1, when continuously printing a small size recording paper, the printing speed (ppm: paper per minute) of recording paper per unit time is set to a normal value up to a certain specified number of sheets, and the specified number of sheets is set. As described above, a technique is disclosed in which the printing paper printing speed per unit time is decreased from a normal value and the recording paper transport interval is lengthened to eliminate the uneven temperature distribution of the fixing roller.
JP-A-10-142975

  However, in the method of Patent Document 1, when the total number of continuously printed recording papers is slightly larger than the specified number, the fixing roller can be used even if the recording paper printing speed per unit time is reduced. Although the degree of non-uniformity in the temperature distribution does not change much, the printing speed per unit time is reduced for the remaining small-sized recording paper after the specified number of sheets, so that the printing efficiency is improved. There is a problem of getting worse.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of continuously printing a small size recording paper so as to eliminate uneven temperature distribution of a fixing roller without reducing printing efficiency. .

  An image forming apparatus according to the present invention includes a large-sized recording sheet having a predetermined size in the width direction orthogonal to the conveyance direction of the recording sheet, and a small-sized recording sheet having a smaller size in the width direction than the large size. And a toner image formed on the recording paper transported by the transporting means, the transporting means transporting the recording paper in the transporting direction, and the width direction being the longitudinal direction. In order to make the temperature distribution of the fixing roller uniform, the fixing roller for fixing the fixing roller, the continuous printing number setting means for setting the continuous printing number of the small-size recording paper based on the operation command from the user, A conveyance interval setting means for setting a predetermined conveyance interval of the recording paper according to the continuous print number set by the continuous print number setting means, and a conveyance interval set by the conveyance interval setting means. Wherein by controlling the conveying means such small-sized recording sheet is conveyed, characterized in that it comprises a print control means for printing an image on a recording sheet of the small size.

  According to this configuration, the continuous print number setting means sets the continuous print number, which is the total number of small-sized recording papers to be continuously printed, and the temperature distribution of the fixing roller is set according to the set continuous print number. A uniform conveyance interval is set by the conveyance interval setting unit, and the conveyance unit is controlled so that a small size recording paper is conveyed at the set conveyance interval, and an image is recorded on the small size recording paper. Printed.

  That is, since the conveyance interval of the recording paper is set to a value that makes the temperature distribution of the fixing roller uniform, the fixing roller passes the recording paper, and the portion that does not come into contact with the recording paper This temperature difference becomes smaller before the next recording sheet is passed, and the temperature distribution of the fixing roller can be made uniform even when a small size recording sheet is continuously printed. Further, since the conveyance interval of the recording paper is a value determined according to the number of continuous prints, it is a case where the number of continuous prints is slightly larger than the specified number as in the method of Patent Document 1. However, the transport speed of the recording paper after the specified number of sheets is not lowered (the transport interval is not increased), and printing can be performed efficiently.

  Further, in the above configuration, the image forming apparatus further includes an idle time setting unit that sets an idle rotation time of the fixing roller according to the continuous print number set by the continuous print number setting unit, and the print control unit includes the idle rotation time setting unit. It is preferable that the fixing roller is idled by the idle rotation time set by the time setting unit.

  According to this configuration, since the fixing roller is idled after the end of continuous printing, the heat of one roller constituting the fixing roller is absorbed by the other roller, thereby preventing an excessive temperature rise of the fixing roller. Can do.

  Further, in the above configuration, the conveyance interval setting unit may calculate the remaining time of the idle rotation time when the start of continuous printing of the small size recording paper is instructed while the fixing roller is idle. It is preferable to correct the continuous print number set by the continuous print number setting means and set the recording paper conveyance interval based on the corrected continuous print number.

  According to this configuration, when continuous printing of a small size recording paper is newly started while the fixing roller is idling at the end of continuous printing of the small size recording paper, the remaining time of the idling time is reduced. Based on the corrected number of continuous prints based on the corrected number of continuous prints, the feeding interval of small-sized recording paper that is newly continuously printed is set. The recording paper can be conveyed so that the temperature of the fixing roller whose temperature has not been sufficiently lowered is lowered, and continuous printing of a small-size recording paper can be started promptly.

  Further, in the above configuration, when the print control unit is instructed to start printing of the large-size recording paper while the fixing roller is idling, the printing control unit sets the idling time setting unit. It is preferable that printing of the large-size recording paper is started after waiting for the idling time to elapse.

  According to this configuration, when a small size continuous printing is finished and a printing instruction for a large size recording sheet is made while the fixing roller is idle, the large size recording paper is passed after the idle rotation time has elapsed. Since printing of the recording paper is started, it is possible to print a large size recording paper after sufficiently reducing the temperature of the fixing roller and making the temperature distribution uniform, and a toner image of the large size recording paper can be printed. It can be fixed uniformly.

  Further, the image forming apparatus according to the present invention includes a large-sized recording sheet having a predetermined size in the width direction perpendicular to the conveyance direction of the recording sheet, and a small size having a smaller size in the width direction than the large size. An image forming apparatus that prints recording paper, a transport unit that transports the recording paper in the transport direction, a fixing roller that fixes the toner image formed on the recording paper with the width direction as a longitudinal direction, and a user The continuous print number setting means for setting the continuous print number of the small-size recording paper based on the operation command from and the continuous print number set by the continuous print number setting means The idle rotation time setting means for setting the idle rotation time of the fixing roller, and the continuous rotation time set by the idle rotation time setting means when the continuous printing of the small-size recording paper is completed. Characterized in that it comprises a print control means for idle roller.

  According to this configuration, the continuous print number setting means sets the continuous print number that is the total number of small-sized recording papers to be continuously printed, and the idle time corresponding to the set continuous print number is set to the idle rotation. The fixing roller is idled at the end of continuous printing according to the set idling time set by the time setting means, so the temperature distribution of the fixing roller can be maintained even when continuous printing of small size recording paper. In addition to being able to make it uniform, it is possible to prevent an excessive temperature rise of the fixing roller.

  According to the present invention, the temperature distribution of the fixing roller can be made uniform even when small-size recording paper is continuously printed.

  FIG. 1 is an overall schematic diagram of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 includes a network printer printer, a facsimile, and a digital multifunction peripheral having various functions such as a copy function, a printer function, a scanner function, and a facsimile function.

  The image forming apparatus 1 is disposed above the sheet feeding unit 100, a sheet conveying unit 200 disposed above the sheet feeding unit 100, and a sheet conveying unit 200 disposed below the sheet feeding unit 100. The image forming unit 300, the fixing unit 400 disposed above the image forming unit 300, and the image reading unit 500 disposed above the image forming unit 300 and the fixing unit 400 are provided.

  The sheet feeding unit 100 feeds a stack of sheets stacked and loaded in the sheet feeding cassette 101 one by one from the uppermost sheet to the sheet conveying unit 200 by the rotation operation of the sheet feeding roller 115. The paper transport unit 200 transports the paper fed from the paper feed unit 100 to the image forming unit 300 by various roller pairs 202. Further, the paper feeding unit 100 discharges the paper on which the image is formed in the image forming unit 300 and the fixing unit 400 to a paper discharge tray 204 provided on the side of the apparatus main body 2 by the discharge roller 205.

  The image reading unit 500 irradiates a document placed on the contact glass with light from an exposure lamp, and guides the reflected light to a photoelectric conversion unit including a CCD line sensor or the like through a reflecting mirror. Read image information. The image forming unit 300 is disposed below the image reading unit 500 and forms a predetermined toner image on a sheet by an electrophotographic process. The image forming unit 300 includes a photoconductive drum 301 having photoconductivity that is rotatably supported. Around the photosensitive drum 301, a charging device 302, an exposure device 303, a developing device 304, a transfer device 305, a cleaning device 306, and a charge removal device (not shown) are disposed along the rotation direction.

  The fixing unit 400 is disposed downstream of the image forming unit 300 in the sheet conveyance direction, and heats the sheet on which the toner image has been transferred in the image forming unit 300 with a pair of fixing rollers 401 between them. Fix the image.

  The basic operation state of the image forming apparatus 1 will be briefly described. The photosensitive drum 301 that rotates clockwise in FIG. 1 by the charging device 302 is uniformly charged, and the image information read by the image reading unit 500 is read. Based on the above, an electrostatic latent image is formed on the photosensitive drum 301 by image exposure from an exposure device 303 (laser scanning device or the like), and a toner composed of a magnetic material is attached to the electrostatic latent image by the developing device 304. An image is formed.

  The sheet is conveyed from the sheet feeding unit 100 to the image forming unit 300 toward the photosensitive drum 301 on which the toner image is formed as described above, and is transferred from the transfer roller or the like in the image forming unit 300. The toner image on the surface of the photosensitive drum 301 is transferred onto a sheet by the transfer device 305. The sheet onto which the toner image has been transferred is separated from the photosensitive drum 301 and conveyed to the fixing unit 400 to fix the toner image. The sheet that has passed through the fixing unit 400 is discharged to the sheet discharge tray 204 via the discharge roller 205. After the transfer by the transfer device 305, the photosensitive drum 301 is removed by the cleaning device 306 and the charge removal device to remove residual toner and residual charge, and is charged again by the charging device 302 as necessary.

  FIG. 2 is a block diagram of the image forming apparatus 1. The image forming apparatus 1 includes a control unit 10, a conveyance unit 20, a printing unit 30, a fixing roller 40, an operation display unit 50, and a scanner unit 60. The control unit 10 includes a CPU, a ROM, a RAM, and the like, and controls the entire image forming apparatus 1. In the present embodiment, the control unit 10 includes a continuous print number setting unit 11, a conveyance interval setting unit 12, an idle rotation time setting unit 13, a print control unit 14, and a storage unit 15. These functions are realized by the CPU executing a control program stored in the ROM.

  The continuous print number setting unit 11 sets the continuous print number in accordance with an operation command received from the operation display unit 50 and specifying the total number of small-size recording sheets to be continuously printed.

  The conveyance interval setting unit 12 refers to the conveyance interval determination table 151, and the number of prints per unit time (ppm) of a small-size recording paper that is predetermined with respect to the continuous print number set by the continuous print number setting unit 11. ; Paper per minute)) is specified to set the conveyance interval of the small-size recording paper. Here, the conveyance interval refers to an interval between recording sheets continuously conveyed by the conveyance unit 20. Since the transport unit 20 transports the recording paper at a constant speed, the print control unit 14 adjusts ppm by changing the timing of picking up the recording paper. Therefore, the recording paper conveyance interval decreases as the ppm increases.

  Further, when the printing control unit 14 is notified of the remaining time to be described later, the conveyance interval setting unit 12 specifies the converted continuous print number for the notified remaining time with reference to the conversion table 153, and specifies the specified conversion continuous By adding the number of prints to the continuous print number set by the continuous print number setting unit 11, correcting the continuous print number, and specifying ppm relative to the corrected continuous print number, the conveyance interval of the small-size recording paper can be set. to correct.

  The idle rotation time setting unit 13 refers to the idle rotation time determination table 152, specifies a predetermined idle rotation time for the continuous print number set by the continuous print number setting unit 11, and specifies the specified idle rotation time. Is set as the idling time of the fixing roller 40. The idling of the fixing roller 40 refers to an operation of turning off the heater built in the fixing roller 40 and rotating the fixing roller 40 without passing the recording paper.

  The print control unit 14 controls the transport unit 20 so that the recording paper is transported according to the transport interval set by the transport interval setting unit 12. Further, when the print control unit 14 detects that the recording paper conveyed by the conveyance unit 20 has reached the printing unit 30 by a paper detection sensor (not shown), the print control unit 14 applies toner corresponding to the image data to the recording paper. The printing unit 30 is controlled so that an image is formed.

  The print control unit 14 controls the heater built in the fixing roller 40 and controls the rotation of the fixing roller 40 to fix the toner image formed by the printing unit 30 on the recording paper. Here, when it is detected by a paper detection sensor (not shown) that the recording paper has reached the fixing roller 40, the print control unit 14 turns on the heater built in the fixing roller 40, and the recording paper becomes the fixing roller 40. When it is detected by a paper detection sensor (not shown) that the paper has passed, the heater built in the fixing roller 40 is turned off.

  Further, when the continuous printing of the small-sized recording paper is finished, the print control unit 14 causes the fixing roller 40 to rotate idly for the idling time set by the idling time setting unit 13. Here, when the operation display unit 50 receives an operation command for continuously printing small-size recording paper while the fixing roller 40 is idling, the remaining time of idling time is left. And the calculated remaining time is notified to the conveyance interval setting unit 12.

  Further, when the operation display unit 50 receives an operation command for printing a large-size recording sheet while the fixing roller 40 is idling, the printing control unit 14 waits for the idling time to elapse. After waiting, a large-size recording sheet is conveyed by the conveyance unit 20. Here, the large size recording paper refers to a recording paper having a size in the width direction perpendicular to the conveyance direction of the recording paper and a length of almost the entire region in the longitudinal direction of the fixing roller 40. The small size recording paper refers to a recording paper whose size in the width direction is smaller than that of a large size recording paper.

  The storage unit 15 includes a nonvolatile memory such as an EEPROM, and stores a conveyance interval determination table 151, an idle rotation time determination table 152, and a conversion table 153. FIG. 3A shows an example of the conveyance interval determination table 151. As shown in FIG. 3A, the conveyance interval determination table 151 includes a column for continuous printing number and a column for ppm. In each field of the continuous print number, a range of the continuous print number is stored, such as “2 to 5” and “6 to 10”. The ppm column stores the number of printed sheets per unit time that is predetermined for each range of the number of continuously printed sheets. For example, when the number of continuously printed sheets is 3, ppm is set to 35.

  Note that the ppm value set for each range of the continuous printing number shown in FIG. 3A is set in advance by experiment, and the temperature distribution of the fixing roller 40 can be made uniform. The largest value is adopted. Here, ppm decreases as the number of continuous prints increases. That is, it can be seen that the recording paper conveyance interval increases as the number of continuous prints increases. Further, the transport interval determination table 151 shown in FIG. 3A is merely an example, and a table that defines ppm more finely or a table that defines ppm more roughly may be employed. .

  FIG. 3B is a diagram showing an example of the idling time determination table 152. As shown in FIG. 3B, the blanking time determination table 152 includes a column for the continuous printing number and a blanking time column. Similar to the transport interval determination table 151, each continuous print number field stores a value range of the continuous print number. In each idle rotation time field, an idle rotation time of the fixing roller 40 predetermined for the range of the number of continuously printed sheets is stored. For example, when the number of continuously printed sheets is 3, the idle rotation time of the fixing roller 40 is “5 minutes”.

  Note that the relationship between the value range of the continuous printing number shown in FIG. 3B and the idling time for each value range is set in advance by experiments or the like, and the temperature distribution of the fixing roller 40 can be made uniform. In addition, the minimum value among the values that can prevent excessive temperature rise of the fixing roller 40 is employed. Further, the idle time determination table 152 shown in FIG. 3B is merely an example, and a table that determines the idle time more finely may be adopted, or a table that roughly determines the idle time may be used. It may be adopted.

  FIG. 3C shows an example of the conversion table 153. As shown in FIG. 3C, the conversion table 153 includes a remaining time column and a converted continuous printing number column. In each field of the remaining time column, a range of remaining time such as “˜5” and “6-10” is stored. Here, the remaining time means that the small size continuous printing is completed while the fixing roller 40 is idling by the idling time set by the idling time setting unit 13 after the small size continuous printing is completed. When the start is instructed, it indicates the time from the instructed time to the end time of the idling time.

  In addition, the converted continuous printing number refers to the temperature distribution in which the fixing roller 40 is prevented from being excessively heated due to the fact that the idling of the fixing roller 40 is interrupted and the idling cannot be sufficiently performed. Is an offset value for correcting the number of continuous prints set for a small-sized recording paper that is newly continuously printed. As shown in FIG. 3C, as the remaining time increases, the converted continuous print number increases. Therefore, the continuous print number set for a small-sized recording sheet to be newly continuously printed is actually It is set to be larger than the total number of recording sheets to be printed. For this reason, the conveyance interval of the newly-recorded small-sized recording paper is longer than the conveyance interval in the total number of recording papers to be actually printed. As a result, excessive temperature rise and temperature distribution of the fixing roller 40 are caused. Unevenness can be prevented.

  The transport unit 20 includes a paper feed roller 115, a paper transport unit 200, and a discharge roller 205 shown in FIG. 1, and transports recording paper under the control of the print control unit 14. The printing unit 30 includes a photosensitive drum 301, a charging device 302, an exposure device 303, a developing device 304, a transfer device 305, a cleaning device 306, and the like shown in FIG. 1, and a toner image corresponding to image data is recorded on recording paper. Form.

  The fixing roller 40 includes the fixing roller 401 shown in FIG. In the fixing roller 401 shown in FIG. 1, the roller disposed on the right side has a built-in heater, and a motor that rotationally drives the roller is attached, and the recording paper is heated and conveyed under the control of the print control unit 14. Then, the toner image is fixed. Further, in the fixing roller 401 shown in FIG. 1, the roller disposed on the left side is a driven roller, and rotates following the right side roller.

  The operation display unit 50 includes a touch panel, a start button for instructing the user to start printing, and a numeric keypad for inputting the number of prints for continuous printing. An operation screen for designating the size of the recording paper used for printing is displayed on the touch panel. The scanner unit 60 includes the image reading unit 500 illustrated in FIG. 1, reads a document, and acquires image data of the document under the control of the print control unit 14.

  Next, an operation when the image forming apparatus 1 prints a small size recording sheet will be described with reference to a flowchart shown in FIG. First, in step S1, when the operation display unit 50 receives an operation command for designating a small size recording sheet from the user (YES in S1), the process proceeds to step S2, and a large size recording is performed instead of a small size. If an operation command for designating paper is received (NO in S1), the process is terminated. For example, if A4 is a large size and B5 is a small size, the user presses a button for designating the B5 recording paper displayed on the touch panel, and the user can select a recording paper to be used for printing. Specify as size.

  In step S2, when the operation display unit 50 receives an operation command for designating the total number of recording sheets to be continuously printed in order to continuously print small size recording sheets from the user (YES in S2), the process is performed. When the process proceeds to step S3 and an operation command for specifying the total number of sheets has not been received (NO in S2), the process ends. Here, the user designates the total number of recording sheets by inputting a numerical value of 2 or more using the numeric keypad. If the user inputs 1 as the total number or does not input the total number, the process is terminated as continuous printing is not performed.

  In step S3, the continuous printing number setting unit 11 sets the total number of sheets designated in step S1 as the continuous printing number. In step S4, when the operation display unit 50 receives an operation command instructing the start of printing from the user (YES in S4), the process proceeds to step S5 and does not receive an operation command instructing the start of printing (S4). NO), the process returns to step S4. When the operation display unit 50 receives an operation command for instructing the start of printing, the print control unit 14 causes the scanner unit 60 to start a document reading operation, and acquires document image data.

  In step S5, the print control unit 14 determines whether or not the fixing roller 40 is currently in the idle state. If it is determined that the fixing roller 40 is not in the idle state (NO in S5), the fixing roller 40 is in the idle state. The conveyance interval setting unit 12 refers to the conveyance interval determination table 151, specifies ppm for the continuous print number set in step S3, and sets the conveyance interval of the recording paper. (S6). Here, in the case of the idling state, the user gives an instruction to continuously print small-sized recording paper before the flowchart is started, and the flowchart is executed according to the instruction, and the fixing roller 40 is turned on. It corresponds to the state where it is idle.

  On the other hand, if it is determined in step S5 that the fixing roller 40 is currently in the idle state (YES in S5), the remaining time of the idle time is calculated (S7), and the calculated remaining time is calculated. Is conveyed to the conveyance interval setting unit 12 and the idle rotation of the fixing roller 40 is stopped.

  In step S8, the conveyance interval setting unit 12 refers to the conversion table 153, specifies the converted continuous print number for the remaining time, and adds the specified converted continuous print number to the continuous print number set in step S3. Correct the number of continuous prints. Then, the ppm for the continuous print number corrected with reference to the conveyance interval determination table 151 is specified, and the specified ppm is set as the conveyance interval of the recording paper.

  Here, the print control unit 14 includes an idle time timer for measuring the idle rotation time of the fixing roller 40, and an operation for instructing the start of printing by the operation display unit 50 during the measurement of the idle time timer. When the command is received, it is determined that the fixing roller 40 is in the idling state. On the other hand, the print control unit 14 determines that the fixing roller 40 is not in the idling state when the idling time counting timer is not performing the timing operation when the print start operation command is received.

  In addition, the print control unit 14 leaves the time from the time measured by the idle time counting timer when the print start operation command is received to the end time of the idle time set by the idle time setting unit 13. Calculate as time.

  In step S9, the print control unit 14 controls the transport unit 20 to transport the recording paper so that the recording paper is transported at the transport interval set in step S6 or step S8. In step S <b> 10, when the recording paper conveyed by the conveyance unit 20 reaches the printing unit 30, the printing control unit 14 drives the printing unit 30 to generate a toner image corresponding to the image data acquired by the scanner unit 60. Form on recording paper.

  In step S11, the print control unit 14 determines whether or not the number of print sheets of the recording paper has reached the continuous print number set in step S3, and determines that it has reached the continuous print number (YES in S11). ), The process proceeds to step S12, and if it is determined that the number of continuous prints has not been reached (NO in S11), the process returns to step S9.

  In step S12, the idle time setting unit 13 refers to the idle time determination table 152, identifies the idle time for the continuous print number set in step S3, and uses the identified idle time for the fixing roller 40. Set as turning time.

  In step S <b> 13, the printing control unit 14 starts the time counting operation of the idle time counting timer, and idles the fixing roller 40 until the idle time counting timer runs to the idle time set by the time setting unit 13. Let it turn. However, if the start of continuous printing of small size recording paper is instructed while the idle rotation time is being measured, the print control unit 14 stops the idle rotation of the fixing roller 40 and the instructed small size recording. Start continuous printing of paper.

  Next, an operation when the image forming apparatus 1 prints a large size recording sheet will be described with reference to the flowchart of FIG. First, in step S21, when the operation display unit 50 receives an operation command for designating a large size recording paper as the size of the recording paper used for printing (YES in S21), the process proceeds to step S22. When an operation command is received that designates not a small size but a small size recording paper as the size of the recording paper to be used for printing (NO in S21), the process ends. For example, if A4 is a large size and B5 is a small size, the user presses a button for designating the A4 recording paper displayed on the touch panel, so that the recording paper used for printing is printed on the large size recording paper. Specify as size.

  In step S22, when the operation display unit 50 receives an operation command instructing the start of printing from the user (YES in S22), the process proceeds to step S23 and does not receive an operation command instructing the start of printing (S22). NO), the process returns to step S22. When the operation display unit 50 receives an operation command for instructing the start of printing, the print control unit 14 causes the scanner unit 60 to start a document reading operation, and acquires document image data.

  In step S23, the printing control unit 14 determines whether or not the fixing roller 40 is currently idle, and if it is determined that the fixing roller 40 is not idle (NO in S23), controls the conveyance unit 20. Then, the conveyance of the large size recording paper is started, and the printing process is performed on the large size recording paper. On the other hand, if it is determined in step S23 that the fixing roller 40 is idle (NO in S23), the process returns to step S23. That is, when the start of printing on a large size recording sheet is instructed while the fixing roller 40 is idling, after waiting for the idling time set by the idling time setting unit 13 to pass, A printing process is performed on the recording paper of the size. Here, in the case of the idling state, before starting this flowchart, the user gives an instruction to continuously print small-sized recording paper, and the flowchart shown in FIG. The state where the roller 40 is idling corresponds.

  As described above, according to the image forming apparatus 1, the continuous print number setting unit 11 sets the continuous print number that is the total number of small-sized recording sheets to be continuously printed, and the set continuous print number. Accordingly, a conveyance interval that makes the temperature distribution of the fixing roller 40 uniform is set by the conveyance interval setting unit 12, and printing control is performed so that a small-sized recording sheet is conveyed at the set conveyance interval. The conveyance unit 20 is controlled by the unit 14.

  That is, since the conveyance interval of the recording paper is set to a value that makes the temperature distribution of the fixing roller uniform, the fixing roller passes the recording paper, and the portion that does not come into contact with the recording paper The temperature difference between the fixing roller is reduced until the next recording paper is passed, and the temperature distribution of the fixing roller can be made uniform until the next recording paper is passed. Even when the recording paper is continuously printed, the temperature distribution of the fixing roller can be made uniform.

  Further, since the conveyance interval of the recording paper is a value determined according to the number of continuous prints, it is a case where the number of continuous prints is slightly larger than the specified number as in the method of Patent Document 1. However, the transport speed of the recording paper after the specified number of sheets is not lowered (the transport interval is not increased), and printing can be performed efficiently.

  In addition, the idle rotation time in which the temperature distribution of the fixing roller is made uniform according to the set continuous printing number is set by the idle rotation time setting unit 13, and the fixing roller 40 is set according to the set idle rotation time. Is idled at the end of continuous printing of small-size recording paper, so uniform non-uniform temperature distribution of the fixing roller caused by passing small-size recording paper and preventing excessive temperature rise can do.

1 is an overall schematic diagram of an image forming apparatus according to an embodiment of the present invention. 1 shows a block diagram of an image forming apparatus. (A) is a figure which showed an example of the conveyance space | interval determination table, (b) is a figure which showed an example of the idle time determination table, (c) is a figure which showed an example of the conversion table 153. . 6 is a flowchart illustrating an operation when the image forming apparatus prints a small-sized recording sheet. 6 is a flowchart illustrating an operation when the image forming apparatus prints a large-size recording sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control part 11 Continuous printing sheet number setting part 12 Conveyance interval setting part 13 Empty rotation time setting part 14 Print control part 15 Storage part 151 Conveyance interval determination table 152 Conversion table 153 Empty rotation time determination table 20 Conveyance part 30 Printing Unit 40 fixing roller 50 operation display unit 60 scanner unit

Claims (5)

An image that can be printed on a large-size recording paper having a predetermined size in the width direction perpendicular to the conveyance direction of the recording paper and a small-size recording paper having a smaller size in the width direction than the large size A forming device,
Conveying means for conveying the recording paper in the conveying direction;
A fixing roller that fixes the toner image formed on the recording paper conveyed by the conveying means, the width direction being the longitudinal direction;
Based on an operation command from a user, continuous printing number setting means for setting the continuous printing number of the small size recording paper,
A conveyance interval setting unit that sets a predetermined conveyance interval of the recording paper according to the continuous print number set by the continuous print number setting unit in order to make the temperature distribution of the fixing roller uniform;
Printing means for printing the image on the small-sized recording paper by controlling the conveying means so that the small-sized recording paper is conveyed by the conveyance interval set by the conveyance interval setting means. An image forming apparatus. An idle time setting means for setting an idle rotation time of the fixing roller after completion of continuous printing according to the continuous print number set by the continuous print number setting means;
The image forming apparatus according to claim 1, wherein the printing control unit causes the fixing roller to rotate idle by an idle rotation time set by the idle rotation time setting unit at the end of continuous printing.   The conveyance interval setting means, when the start of continuous printing of the small size recording paper is instructed while the fixing roller is idling, based on the remaining time of the idling time, 3. The image according to claim 2, wherein the continuous printing number set by the number setting means is corrected, and the conveyance interval of the small-sized recording paper to be continuously printed is set based on the corrected continuous printing number. Forming equipment.   When the printing control unit is instructed to start printing of the large-sized recording paper while the fixing roller is idling, the idling time set by the idling time setting unit elapses. 4. The image forming apparatus according to claim 2, wherein printing of the large-sized recording sheet is started after waiting. An image forming apparatus that prints a large size recording sheet having a predetermined size in the width direction perpendicular to the conveyance direction of the recording sheet and a small size recording sheet having a smaller size in the width direction than the large size. There,
Conveying means for conveying the recording paper in the conveying direction;
A fixing roller for fixing the toner image formed on the recording paper, the width direction being the longitudinal direction;
Based on an operation command from a user, continuous printing number setting means for setting the continuous printing number of the small size recording paper,
An idle time setting means for setting an idle time of the fixing roller after completion of continuous printing according to the continuous print number set by the continuous print number setting means;
An image forming apparatus, comprising: a print control unit that causes the fixing roller to rotate idle by an idle rotation time set by the idle rotation time setting unit when continuous printing of the small size recording paper is completed.

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