JP2012118463A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing transfer control of sheets by a simple system.SOLUTION: It is determined whether the previous job is completed or not (Step S2). When it is determined that the previous job is completed, lapsed time starts to be counted with the use of a timer (Step S4). Then it is determined whether a new job (current job) is input or not (Step S6). When it is determined that the new job (current job) is input (YES in Step S6), the counting timer is checked (Step S8). Then a paper-feed timing table is selected (Step S10). Then the paper size of the previous job is checked (Step S12). Then paper feed timing is set from the selected paper-feed timing table (Step S14). Then, when it is determined that the paper feed timing expires, paper feed is ordered (Step S18).

Description

  The present invention relates to an image forming apparatus that forms an image by an electrophotographic method, and particularly relates to sheet conveyance control.

  Conventionally, as a method for fixing toner on a recording paper, it is known to use a fixing device that applies heat and pressure to the recording paper on which the toner is adhered.

  The fixing device basically includes a fixing roller as a heating member that is heated by providing a heater lamp and the like, and a pressure roller as a pressure member that is in pressure contact with the fixing roller.

  The toner on the recording paper is fixed by rotating the pair of rollers to feed the recording paper to the nip portion to be nipped and conveyed.

  On the other hand, when recording paper of different sizes (paper widths) is passed, the temperature of the non-paper passing portion (end of the fixing roller) is gradually increased, and heat is not removed from the recording paper. A temperature difference will occur between these temperatures.

  Patent Document 1 proposes a thermistor for detecting the temperature difference between the central portion and the end portion, and temperature control based on the detection result of the thermistor.

  On the other hand, if there is a temperature difference between the center and the edge, it is necessary to wait for the temperature in the center to reach the specified temperature before feeding, transporting, imaging, and fixing. Time occurs.

  Patent Document 2 discloses a technique for adjusting the sheet feeding timing and the like based on a temperature difference between a central portion and an end portion using a thermistor.

JP 2008-216698 A JP 2007-298553 A

  However, for the form controlled based on the measured value of the thermistor, the measured value of the thermistor is very important, but from the state where the thermistor and the fixing roller are in normal contact according to the tolerance of the thermistor installation. There is a possibility of deviating from the true value obtained. In addition, there is a possibility of deviation from the true value due to changes in the shape of the fixing roller and thermistor due to changes over time. In addition, the thermistor itself also varies from individual to individual and may deviate from the true value.

  Therefore, when executing control based on the actual measurement value of the thermistor, it is necessary to make the material and parts expensive, and complicated control is costly. Further, until the printing is completed for each apparatus. There is a problem that variation occurs between the two.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of performing sheet conveyance control by a simple method.

  An image forming apparatus according to an aspect of the present invention includes: an image forming unit that forms an image on a sheet according to a job input; a fixing device that fixes an image formed on the sheet by the image forming unit; And a controller for controlling the whole. The fixing device includes a fixing roller having a heater lamp with a constant light distribution in the longitudinal direction. The controller uses a heater lamp to fix the fixing roller for the current job in accordance with the paper width in the longitudinal direction in contact with the fixing roller at the time of image formation of the previous job and the elapsed time from the completion of the previous job to the input of the current job. In order to warm the sheet to a predetermined temperature, the sheet feeding timing from the input of the current job to the sheet feeding using the transport unit is adjusted.

  Preferably, when the elapsed time from the completion of the previous job to the input of the current job is equal to or shorter than a predetermined time, the paper feed timing for feeding paper using the transport unit in the current job is advanced.

  Preferably, the sheet feeding timing for feeding the sheet is earlier when the width of the sheet in the longitudinal direction in contact with the fixing roller at the time of image formation of the previous job is short.

  Preferably, the apparatus further includes a storage unit that stores a plurality of paper feed timing tables in advance, and the plurality of paper feed timing tables are provided according to an elapsed time from the completion of the previous job to the input of the current job. The paper feed timing for feeding paper corresponding to the various paper widths in the longitudinal direction that contact the fixing roller at the time of image formation of the previous job is set, and the controller performs from the completion of the previous job to the input of the current job. One of a plurality of paper feed timing tables pre-stored in the storage unit according to the elapsed time of the transfer, and the transport unit based on the paper feed timing according to the paper width of the previous job in the selected paper feed timing table Is instructed to feed paper.

  In the image forming apparatus according to an aspect of the present invention, the controller includes a heater according to a longitudinal paper width in contact with the fixing roller at the time of image formation of the previous job and an elapsed time from completion of the previous job to input of the current job. In order to heat the fixing roller to a predetermined temperature for the current job using the lamp, the paper feed timing from the input of the current job to the paper feeding using the transport unit is adjusted. Accordingly, the paper feed timing is adjusted based on the paper width and elapsed time of the previous job, not the control using a thermistor or the like, so that the paper transport control can be executed by a simple method.

1 is a diagram illustrating an overview of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a printer 14 of an image forming apparatus 1 according to an embodiment of the present invention. It is the schematic explaining the structure of the fixing roller 32a according to embodiment of this invention. It is a figure explaining the temperature change at the time of the printing of the fixing roller according to embodiment of this invention, and after completion | finish of printing. FIG. 6 is a diagram for explaining a paper feed start timing according to the temperature of a conventional fixing roller 32a. It is another figure explaining the paper feed start timing according to the temperature of the conventional fixing roller 32a. It is a flowchart explaining the setting of the paper feed timing according to the embodiment of the present invention. It is a figure explaining the paper feed timing table according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

(Overview of the image forming apparatus 1)
FIG. 1 is a diagram illustrating an overview of an image forming apparatus 1 according to an embodiment of the present invention.

  With reference to FIG. 1, an MFP (Mutli Function Peripheral), which is an example of an image forming apparatus, is described. The present invention can be similarly applied to a copying machine, a printer, a facsimile, or the like.

  The image forming apparatus 1 includes an operation unit 11 and an operation display 12 in an operation panel 10 located at the top of the main body. The operation unit 11 receives various instructions from the user input through the key 11a. The operation display 12 displays an instruction menu for the user.

  A scanner 13 and a feeder 17 are provided on the upper surface of the main body. The feeder 17 sends the document to the scanner 13. A printer 14 is provided on the side of the main body. A tray 19 and a paper feeding unit 18 are provided at the lower part of the main body.

  A sheet as a recording medium on which an image is printed by the printer 14 is discharged to the tray 19. The paper supply unit 18 supplies paper to the printer 14.

  Here, a case where a plurality of paper supply units 18 are provided is shown, and it is assumed that papers having different paper sizes are stored. For example, various papers such as A3 size, A4 size, A5 size, B4, B5 size and the like can be mentioned.

  A plurality of image forming units (printers) are provided inside the main body. An image pattern is formed by applying ink to the development pattern developed by the developing device, and the image pattern by the ink is printed on a recording medium.

  FIG. 2 is a diagram illustrating the configuration of the printer 14 of the image forming apparatus 1 according to the embodiment of the present invention.

  Referring to FIG. 2, the image forming apparatus 1 has a tandem transfer unit, and sequentially superimposes toners of four colors of yellow (Y), magenta (M), cyan (C), and black (K). To form a color image. In FIG. 2, the components corresponding to yellow (Y), magenta (M), cyan (C), and black (K) are identified by a, b, c, and d, respectively.

  As shown in FIG. 1, the image forming apparatus 1 develops an electrostatic latent image formed on the photoconductor 3 by exposure by the exposure device 6 by the developing device 4, and transfers the obtained toner image to a primary transfer roller ( (Not shown) is transferred to the intermediate transfer belt 2 and further transferred to a recording sheet.

  That is, in the image forming apparatus 1, four-color cartridges (imaging units) 28 of Y, M, C, and K are arranged in a tandem arrangement, and toner images (toner images) of the respective colors formed by these cartridges 28. Image) is superimposed on the intermediate transfer belt 2 and transferred and synthesized.

  Each cartridge 28 includes a developing device 4, a charging device 5, an exposure device 6, and the like arranged in the vicinity of the drum-shaped photoconductor 3. The surface of the photoreceptor 3 is charged to a predetermined voltage (charging potential) V0 by the charging device 5, and an electrostatic latent image is formed by exposure from the exposure device 6. This electrostatic latent image is obtained by supplying toner charged from the developing roller to a potential gap ΔV between the potential of the electrostatic latent image and the developing bias voltage Vdc by the developing roller to which the developing bias voltage Vdc is applied. And visualized.

  The toner image visualized on the surface of the photoreceptor 3 is primarily transferred to the intermediate transfer belt 2 by the primary transfer roller. The toner image on the intermediate transfer belt 2 is secondarily transferred by the secondary transfer roller 41 to the recording paper conveyed by the cassette paper supply roller 8 from the paper supply unit 18 containing the recording medium. The recording paper conveyed by the cassette paper supply roller 8 is temporarily stopped by the timing roller 38 as necessary. Further, a manual paper feed roller 9 is provided for transporting the recording paper to the timing roller 38 when the recording paper is supplied manually. A paper detection sensor 29 is provided on the upstream side of the timing roller 38, and timing control is performed according to the detection output of the sensor. In addition, a paper material detection sensor 22 is also provided to determine whether thick paper, plain paper, or the like. A paper detection sensor 30 is also provided to determine whether or not the fixing device has passed.

  The toner image secondarily transferred onto the recording paper is fixed by the fixing roller 32a. A pressure roller 32b is provided so as to face and contact the fixing roller 32a. A temperature sensor 102 (thermistor) for detecting the surface temperature of the fixing roller 32a is provided in the vicinity of the fixing roller 32a, and a heater lamp 100 for heating the fixing roller 32a is provided inside the fixing roller 32a. ing. A fixing loop sensor 27 is provided upstream of the fixing roller 32a.

  The fixed recording paper is discharged onto a paper discharge tray by a paper discharge roller 33 or conveyed to a double-sided conveyance path 35. The double-sided conveyance path 35 is connected to a path leading to the timing roller 38 described above. The double-sided conveyance path 35 is provided with double-sided conveyance rollers 34 a and 34 b, and the double-sided conveyance motor 45 drives the double-sided conveyance rollers 34 a and 34 b so that the recording paper on the double-sided conveyance path 35 is fed to the timing roller 38. It is conveyed to.

  The toner (transfer residual toner) that is not completely transferred by the secondary transfer described above and remains on the intermediate transfer belt 2 is removed and collected by the intermediate transfer belt cleaner 7. That is, after the secondary transfer, the surface of the intermediate transfer belt 2 is cleaned by the intermediate transfer belt cleaner 7. In this embodiment, the intermediate transfer belt cleaner 7 is of a cleaning blade type that is movable between the press contact and the separation with respect to the intermediate transfer belt 2. It is possible to use various types or mechanisms such as a brush type in which the voltage applied to 2 is controlled on and off. The transfer residual toner is collected in a waste toner box 36.

  Above the cartridge 28 is provided a toner bottle 25 that replenishes toner by operating the stirring blade 26. In addition, toner replenishing motors 24a, 24b, 24c, and 24d are provided for operating the stirring blades 26a, 26b, 26c, and 26d, respectively.

  Further, a color PC motor 48, a main motor 44, a fixing motor 46, a color developing motor 40, and a developing motor 42 are provided.

  A controller 200 that controls the motor and the entire image forming apparatus 1 and a memory 202 that stores various programs for controlling the entire image forming apparatus 1 are provided. Although not shown, the controller 200 is provided with a timer for measuring time.

  In this example, the configuration of a printer capable of color development has been described, but the present invention can be similarly applied to a printer capable of only monochrome development.

FIG. 3 is a schematic diagram illustrating the configuration of the fixing roller 32a according to the embodiment of the present invention.
Referring to FIG. 3, a temperature sensor 102 (thermistor) is provided at the center of fixing roller 32a in this example.

  In addition, a heater lamp 100 that uniformly heats the fixing roller 32a, that is, the light distribution is constant in the longitudinal direction, is provided in the fixing roller 32a.

  In this example, the temperature change of the fixing roller 32a when small (A4) size (vertical) paper is passed through the fixing device is shown.

  When a small (A4) size (vertical) sheet is passed, the temperature at the center, which is the part where the fixing roller 32a and the sheet are in contact with each other, is low, and the temperature at the end that is not in contact is high.

  FIG. 4 is a diagram illustrating a temperature change at the time of printing by the fixing roller according to the embodiment of the present invention and after the completion of printing.

  Referring to FIG. 4, temperature changes during printing (thin line) and after printing (thick line) are shown.

  In this example, the case where the fixing setting temperature of the paper at the time of printing is set to 180 ° C. is shown.

  At the time of printing, when a small (A4) size (vertical) sheet is passed through the fixing device, the temperature at the portion where the fixing roller 32a contacts the sheet is deprived of heat, so that the temperature is maintained. The heater lamp 100 is turned on. In this case, since the end of the fixing roller 32a is not in contact with the paper, the heat supplied from the heater lamp 100 is not dissipated and the end temperature rises to 210 ° C.

  After the printing is completed, the heater lamp 100 is turned off, the temperature of the fixing roller 32a changes uniformly, and the temperature drops.

  In this example, it is assumed that the temperature of the fixing roller 32a is maintained at 150 ° C. before printing when a job is input. That is, the temperature of the fixing roller 32a is set to 150 ° C. as the pre-fixing temperature.

  When the job is input again, the temperature of the fixing roller 32a is set to the fixing set temperature 180 ° C.

  In this example, when the heater lamp 100 is turned off and the temperature at the center reaches 150 ° C., the end temperature of the fixing roller 32a immediately after printing is 170 ° C.

  Therefore, it can be seen that the end portion is hotter than the center portion of the fixing roller 32a for a certain predetermined time immediately after printing of the small (A4) size (vertical) paper.

  FIG. 5 is a diagram for explaining the sheet feeding start timing according to the temperature of the conventional fixing roller 32a.

  Referring to FIG. 5A, a case where the pre-fixing temperature T1 is 150 ° C. and the fixing set temperature T2 is 180 ° C. is shown. Conventionally, a time t3 (time required for temperature rise) required for raising the temperature from the pre-fixing temperature T1 to the fixing set temperature T2 when the heater lamp 100 is turned on is calculated.

  Then, since the temperature increase required time t3 is required from the pre-fixing temperature T1 to the fixing set temperature T2, the time from the cassette paper supply roller 8 to the fixing roller 32a is taken into consideration as shown in FIG. The feed timing has been adjusted.

  However, as described with reference to FIG. 4, after the printing of the small (A4) size (vertical) paper is completed, the temperature of the fixing roller 32a changes uniformly, but the small (A4) size (vertical) paper is fixed. When the paper is passed through the apparatus, the temperature at the end is 170 ° C. even when the temperature at the center of the fixing roller 32 a is lowered to 150 ° C. Therefore, when the heater lamp 100 is turned on without the temperature of the end portion being lowered, the temperature of the end portion is conducted to the central portion and raised.

  FIG. 6 is another diagram illustrating the sheet feeding start timing according to the temperature of the conventional fixing roller 32a.

  As described above, the temperature of the fixing roller 32a changes uniformly after the printing is completed, but when a small (A4) size (vertical) sheet is passed through the fixing device, the temperature at the center of the fixing roller 32a. Is 150 ° C., but the end temperature is 170 ° C.

  Therefore, as shown in FIG. 6A, when the next job is input and the heater lamp 100 is turned on before the temperature at the end of the fixing roller 32a is lowered to 150 ° C., the end of the fixing roller 32a is turned on. Therefore, the period until the fixing set temperature T2 of the fixing roller 32a reaches 180 ° C. is shortened. In other words, the time required for the temperature rise from the pre-fixing temperature T1 to the fixing set temperature T2 (time required for temperature rise) is t2.

  Therefore, according to the conventional method, as shown in FIG. 6B, if the paper feed timing is set with the temperature increase required time t3 fixed, a wasteful waiting time t3-t2 = t1 occurs. Will do.

  In the embodiment of the present invention, a paper conveyance control by a simple method, specifically, a method of adjusting the paper feed timing will be described.

  In this example, the paper feed timing is adjusted according to the paper size passed through the fixing device in the previous job and the elapsed time from the completion of the previous job to the current job input.

FIG. 7 is a flowchart illustrating setting of paper feed timing according to the embodiment of the present invention.
This flow is mainly executed when the controller 200 reads a program stored in the memory 202.

  Referring to FIG. 7, first, controller 200 determines whether the previous job has been completed (step S2).

  Next, if controller 200 determines that the previous job has been completed (YES in step S2), controller 200 then starts counting elapsed time using a timer (step S4). If it is determined that the previous job has not been completed (NO in step S2), the state of step S2 is maintained. Note that, as an example, the time when it is determined that the previous job has been completed can be the time when the paper is detected by the paper detection sensor 30.

  Next, the controller 200 determines whether or not a new job (current job) has been input (step S6). Specifically, it is possible to make a determination based on whether or not the user has input an instruction to execute a new job from the operation panel 10 or the like.

  If controller 200 determines in step S6 that a new job (current job) has been input (YES in step S6), it checks the counting timer (step S8).

  Next, the controller 200 selects a paper feed timing table (step S10). Specifically, a paper feed timing table corresponding to the elapsed time is selected from a plurality of paper feed timing tables stored in the memory 202.

FIG. 8 is a diagram illustrating a paper feed timing table according to the embodiment of the present invention.
Referring to FIG. 8, here, a plurality of paper feed timing tables corresponding to the elapsed time are shown. Specifically, tables A to D are shown. Assume that the tables A to D are stored in the memory 202 in advance.

FIG. 8A is a table A whose elapsed time is less than 30 seconds.
Specifically, when the paper size is “A3”, the paper feed timing is “25 s”, the paper size is “A4 portrait”, the paper feed timing is “23 s”, and the paper size is “A4 landscape”. When the paper feed timing is “25 s”, the paper size is “A5 portrait”, the paper feed timing is “20 s”, the paper size is “A5 landscape”, and the paper feed timing is set to “23 s”. Has been.

  Note that the width of the fixing roller 32a varies in the longitudinal direction between the sheet sizes of “A4 portrait” and “A4 landscape”, and the sheet size of “A4 landscape” is larger than the sheet size of “A4 portrait”. The width according to the longitudinal direction is large. The same applies to other paper sizes.

  When the elapsed time is less than 30 seconds, the temperature at the end of the fixing roller 32a is high, and the heat at the end is used for heating the center. The time set at 180 ° C. is shortened and the paper feed timing is shortened.

FIG. 8B is a table B whose elapsed time is 30 seconds or more and less than 1 minute.
Specifically, when the paper size is “A3”, the paper feed timing is “26 s”, the paper size is “A4 portrait”, the paper feed timing is “24 s”, and the paper size is “A4 landscape”. When the paper feed timing is “26 s”, the paper size is “A5 portrait”, the paper feed timing is “21 s”, the paper size is “A5 landscape”, and the paper feed timing is set to “24 s”. Has been.

FIG. 8C is a table C whose elapsed time is 1 minute or more and less than 2 minutes.
Specifically, when the paper size is “A3”, the paper feed timing is “29 s”, when the paper size is “A4 portrait”, the paper feed timing is “27 s”, and when the paper size is “A4 landscape”, When the paper feed timing is “29 s”, the paper size is “A5 portrait”, the paper feed timing is “24 s”, the paper size is “A5 landscape”, and the paper feed timing is set to “27 s”. Has been.

FIG. 8D is a table D with an elapsed time of 2 minutes or more.
Specifically, in the case where the paper size is “A3”, “A4 portrait”, “A4 landscape”, “A5 portrait”, “A5 landscape”, the sheet feeding timing is all set to “30 s”. ing.

  When the elapsed time is 2 minutes or more, there is almost no temperature difference between the central portion and the end portion of the fixing roller 32a, and the pre-fixing temperature is set to 150 ° C. uniformly.

  Note that the table D may be used to set the paper feed timing immediately after the image forming apparatus is started, that is, when there is no previous job.

  Here, the sheet feeding timing table corresponding to the elapsed time listed is that the heater lamp 100 is turned on and the fixing roller 32a is set to the fixing set temperature T2 when a next job is input according to the elapsed time by an experiment in advance. The time until reaching (180 ° C.) is determined by measuring according to the paper size of the previous job. Note that the time may have a certain margin.

  For example, the controller selects Table A when the timer count is less than 30 seconds. The same method applies to other cases.

  Then, the controller 200 confirms the paper size of the previous job (step S12).

  Next, paper feed timing is set (step S14). Specifically, the paper feed timing corresponding to the paper size of the previous job is set according to the selected paper feed timing table.

  As an example, if the table A is selected and the paper size of the previous job is “A4 portrait”, the paper feed timing is set to “23 s”.

  Then, the controller 200 determines whether the paper feed timing has elapsed (step S16).

  If controller 200 determines in step S16 that the paper feed timing has elapsed (YES in step S16), it instructs paper feed (step S18).

  Specifically, the controller 200 instructs the motor as a transport unit to drive the cassette paper feed roller 8.

Then, the process ends (END).
With this method, fixing for the current job using the heater lamp according to the paper width in the longitudinal direction that contacts the fixing roller at the time of image formation of the previous job and the elapsed time from the completion of the previous job to the input of the current job In order to heat the roller to the fixing set temperature, it is possible to adjust the paper feed timing from the current job input until the paper is fed using the roller.

  Therefore, it is possible to efficiently form an image by reducing the waiting time as compared with the case where the sheet feeding timing is fixed as in the conventional method.

  In this method, a paper feed timing table is read according to the elapsed time using a timer, and the paper feed timing according to the paper size of the previous job is set from the paper feed timing table. Therefore, there is an advantage that the control is simple and the cost is low, instead of using a thermistor to set the paper feed timing.

  In addition, by using the same sheet feeding timing table under the same conditions in a plurality of image forming apparatuses, there is no variation in the timing of printing completion among the apparatuses, resulting from tolerances of measured values of the thermistor, errors according to changes over time, and the like. This also avoids the problem of variations in printing completion between apparatuses, and is convenient for the user.

  In this example, the four tables have been described as examples in FIG. 8, but the present invention is not limited to this, and a plurality of paper feed timing tables according to the elapsed time are provided to finely adjust the paper feed timing. You may do it. Also, the paper size is not limited to this example, and a paper feed timing table according to a plurality of paper sizes can be used.

  The image forming apparatus according to the present invention is not limited to the MFP. It is also possible to provide a program that causes a computer (CPU) to function and execute control as described in the above flow. Such a program can be read by a non-transitory computer such as a flexible disk attached to a computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), and a memory card. It can also be recorded on a recording medium and provided as a program product. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.

  The program may be a program module that is provided as a part of a computer operation system (OS) and that calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program according to the present invention.

  The program according to the present invention may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program according to the present invention.

  The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 Intermediate transfer belt, 3 Photoconductor, 4 Developing apparatus, 5 Charging apparatus, 6 Exposure apparatus, 7 Intermediate transfer belt cleaner, 8 Cassette feed roller, 9 Manual feed roller, 10 Operation panel, 11 Operation Part, 11a key, 12 operation display, 13 scanner, 14 printer, 17 feeder, 18 paper feeding part, 19 tray, 22 paper material detection sensor, 24a, 24b, 24c, 24d toner supply motor, 25 toner bottle, 26 stirring blade , 27 Fixing loop sensor, 28 Cartridge, 29, 30 Paper detection sensor, 31 Secondary transfer roller, 32a Fixing roller, 32b Pressure roller, 33 Paper discharge roller, 34a Double-sided conveyance roller, 35 Double-sided conveyance path, 36 Waste toner box , 38 Timing roller, 40 color development mode , 42 developing motor, 44 a main motor, 45 sided conveyance motor, 46 fixing motor, 200 controller, 202 memory.

Claims (4)

An image forming unit that forms an image on a sheet according to a job input;
A fixing device for fixing an image formed on a sheet in the image forming unit;
A transport unit for feeding paper to the image forming unit and the fixing device;
With a controller that controls the whole,
The fixing device includes a fixing roller having a heater lamp with a constant light distribution in the longitudinal direction,
The controller uses the heater lamp to change the length of the sheet in the longitudinal direction in contact with the fixing roller at the time of image formation of the previous job and the elapsed time from the completion of the previous job to the input of the current job. In order to warm the fixing roller to a predetermined temperature, an image forming apparatus that adjusts a paper feed timing from the input of the current job to paper feeding using the transport unit.   2. The image according to claim 1, wherein when the elapsed time from the completion of the previous job to the input of the current job is equal to or shorter than a predetermined time, the paper feed timing for feeding paper using the transport unit in the current job is advanced. Forming equipment.   3. The image forming apparatus according to claim 1, wherein a sheet feeding timing for feeding the sheet is earlier when a width of a sheet in a longitudinal direction in contact with the fixing roller at the time of image formation of the previous job is shorter. A storage unit for storing a plurality of paper feed timing tables in advance;
The plurality of paper feed timing tables are provided according to an elapsed time from the completion of the previous job to the input of the current job,
In each of the paper feed timing tables, paper feed timings for feeding paper corresponding to various paper widths in the longitudinal direction in contact with the fixing roller at the time of image formation of the previous job are set.
The controller selects one of the plurality of paper feed timing tables stored in the storage unit in advance according to the elapsed time from the completion of the previous job to the input of the current job, and the selected paper feed timing table The image forming apparatus according to any one of claims 1 to 3, wherein the image forming apparatus instructs the conveyance unit to feed paper based on a paper feed timing according to a paper width of the previous job.