JP2010097111A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that same image forming quality cannot be maintained before and after changing an image forming speed and a fixing temperature, when the image forming speed and the fixing temperature are changed during image formation for handling the temperature rise at an end part of a fixing device. <P>SOLUTION: The image formation is started after determining the image forming speed and the fixing temperature, based on a printing condition of a printing job, a paper sheet size, the number of sheets for the image formation and the temperature at the end part of a fixing roller. Stop of the image formation or the change of the image forming speed due to the temperature rise at the end part is prevented during the image formation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a print medium.

2. Description of the Related Art Conventionally, some image forming apparatuses that employ an electrophotographic system, an electrostatic recording system, and the like have a fixing unit for performing heat fixing.
The fixing unit introduces the toner image onto the paper by introducing the paper on which the unfixed toner image is formed into a fixing nip portion that is a pressure-contacting portion between the fixing roller and the pressure roller that are pressed against each other. Heat fixing.

  Such a fixing unit has one or more fixing temperature detecting means such as a thermistor in order to control the temperature at which the toner image is heated and fixed.

In the fixing unit as described above, when a sheet having a width smaller than the maximum width of the sheet that can be passed through the roller is continuously passed and thermal fixing of the toner image is performed, it is the center of the roller. While the sheet passing portion maintains a constant temperature, the non-sheet passing portion at the end portion has a phenomenon that the temperature rises due to the heat stored in the heat generating element (for example, a halogen lamp) of the roller.
Such a phenomenon is referred to as temperature rise at the end of the fixing unit.
If the temperature of the end of the roller of the fixing unit rises to a high temperature and exceeds the heat resistance temperature of the components of the fixing unit, these components are damaged by heat.

For this reason, in this type of image forming apparatus, even if the temperature at the end of the roller rises, temperature control is performed so as not to reach the heat resistant temperature.
That is, in order to keep the temperature rise at the end of the roller within a certain limit, a sub-thermistor for detecting the temperature at the end of the roller is arranged in addition to the main thermistor used for controlling the fixing temperature of the fixing unit. When the detected temperature of the sub-thermistor exceeds a predetermined value during formation, control is performed to increase the paper feed interval and lower the throughput, thereby suppressing the temperature rise of the non-sheet passing portion.

However, in recent years, the fixing control temperature has been set high in order to improve the throughput of the apparatus, and accordingly, the difference between the fixing control temperature and the set upper limit temperature of the roller end has become smaller.
For this reason, in the above-described control for increasing the paper feed interval, for example, in an image forming apparatus set to 24 ppm, there is a case where the paper feed interval is increased to about 2 ppm and the throughput is greatly reduced.

Therefore, recently, when the detected temperature of the sub-thermistor exceeds a certain value during image formation, the process parameters have been changed, such as resetting the image formation speed slower and resetting the fixing temperature lower during the image formation. By taking measures to increase the margin for the temperature rise at the end of the roller, a reduction in throughput during image formation of small-size paper has been suppressed to some extent.
JP 2004-212769 A

However, for example, when changing various process parameters such as the voltage value of the image forming means and the temperature of the fixing roller to switch the image forming speed to a low speed in order to cope with the temperature rise at the edge during printing of a small-sized pamphlet or the like. Requires time for the voltage value and temperature to reach the target set value and stabilize.
For this reason, there is a problem that the image quality cannot be kept constant until the voltage value and temperature are stabilized and also when the state before and after the change of the image forming speed is compared.

  In order to solve the above-described problems, the configuration of the image forming apparatus of the present invention includes a data storage unit that stores image formation data in units of print jobs, and an image that forms an image on a medium corresponding to the image formation data. In the image forming apparatus including the forming mechanism and the fixing unit that includes the fixing roller and thermally fixing the medium, the fixing unit further includes an end temperature detecting unit that detects the temperature of the end of the fixing roller. When the determination result of the job determination unit and the job determination unit are negative, whether the sheet passing width of the medium of the print job is the maximum width that can be passed to the apparatus is determined. The printing on the basis of the temperature of the end of the fixing roller detected by the end temperature detecting unit, the number of print jobs printed, the printing condition on the medium, and the printable upper limit temperature of the end of the fixing roller. Job image formation speed A main control unit for previously set before the image formation, with said image forming mechanism is characterized by starting the image formation of the print job in the image forming speed set.

According to the present invention, before image formation is started, an image formation process is performed based on the print job print conditions, the paper size, the maximum printable temperature at the end of the fixing roller, the number of prints, and the end temperature of the fixing roller. Since the image forming speed and the fixing temperature, which are parameters, are set, all the printing of the print job can be completed before the temperature of the roller end reaches the upper limit temperature.
Therefore, it is possible to efficiently perform printing with a certain quality for each job.

  A feature of the present invention is that the printing speed is determined by determining that the temperature during printing at the end portion, which is a non-sheet passing portion of the fixing roller of the fixing portion, does not exceed the printable upper limit temperature. The method for determining the printing speed will be described later.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings.

(Description of Configuration of Example 1)
FIG. 1 is a functional block diagram of Embodiment 1 of the present invention.

  As shown in FIG. 1, a printer 1 as an image forming apparatus is transmitted from a main control unit 101 that controls the printer 1, a process parameter setting unit 102 that sets process parameters in printing, and a host device 123. Printable sheet number prediction that predicts the number of printable sheets by obtaining a job determination unit 103 that determines whether or not the sheet passing width of the print job is the maximum width and the detection value of the sub-thermistor 26 via the end temperature detection unit 113 Unit 104, printable sheet number prediction table storage unit 116 that stores the printable sheet number for each edge temperature, paper size, paper size, printing condition, and printing speed as data, and data reception for receiving a print job Unit 106, a data storage unit 105 having a FIFO function in which received print jobs are stored, each of rollers 6 to 8, 13 and a conveyor belt 37. The conveyance control unit 107 that controls the conveyance mechanism 114 configured by the discharge rollers 27 to 30 and the control of the image formation mechanism 115 configured by the image forming units 14 to 17, the exposure devices 18 to 21, and the transfer rollers 9 to 12. An image formation control unit 108 that performs the control, a drive control unit 111 that performs drive control of the fixing roller 23 and the pressure roller 24, and a temperature control unit 112 that performs on / off control of the halogen lamp 32 based on the detection value of the main thermistor 25. From the fixing control unit 110 that manages the drive control unit 111, the temperature control unit 112, and the end temperature detection unit 113, the display unit 121 for displaying to the user, the operation panel 122 for inputting the setting value from the user, and the like. Composed.

FIG. 2 is a cross-sectional view of a printer 1 as an image forming apparatus.
The printer 1 includes a paper cassette 2 in which a print medium 3 is set, a paper feed roller 5 for feeding the print medium 3, a retard roller 4 for separating stacked paper when the paper is fed, and a paper feed roller 5. To the registration roller 7 for conveying the printed paper, the pressure roller 6 that is pressed and driven by the roller 7, the image forming units 14-17 for forming a toner image, and the image forming units 14-17 Transfer rollers 9 to 12 that apply a transfer voltage, a conveyance belt 37 that conveys the print medium 3, a driving roller 8 that drives the conveyance belt 37, a belt idle roller 13, a fixing unit 22 that performs thermal fixing, and a fixing unit 22 The discharge rollers 27 to 30 convey the print medium 3 heated and fixed by the above, and the face down stacker 31 from which the print medium 3 is discharged.

FIG. 3 is a schematic diagram of the image forming unit 14.
The image forming unit 14 includes a photosensitive drum 33, an exposure device 18 that forms an electrostatic latent image by exposing the photosensitive drum 33 based on image formation data, a developing roller 34 that supplies toner to the photosensitive drum 33, and the like. The
Since the image forming units 15 to 17 have the same configuration as that of the image forming unit 14, the description thereof is omitted.

FIG. 4 is a schematic diagram of the fixing unit 22.
The fixing unit 22 applies heat to the print medium 3 to thermally fix the toner image on the print medium 3, a pressure roller 24 that applies pressure to the print medium 3, and a fixing roller 23 at the center of the sheet passing unit. A main thermistor 25 that detects the surface temperature, a sub-thermistor 26 that detects the surface temperature of the end portion of the fixing roller 23 that is a non-sheet passing portion, and the like. A halogen lamp 32 (see FIG. 1) is built in the fixing roller 23 in order to heat the fixing roller 23.

In the above configuration, the print medium 3 is fed from the paper cassette 2.
The print medium 3 fed by the paper feed roller 5 and separated by the retard roller 4 is transported and further transported onto the transport belt 37 by the pressure roller 6 driven by the registration roller 7.

An electrostatic latent image is formed by the exposure devices 18 to 21 on each photosensitive drum in the image forming units 14 to 17 configured for four colors of black, yellow, magenta, and cyan, and toner is further adhered. An image is formed.
The transfer rollers 9 to 12 transfer the toner image formed on the photosensitive drum 33 onto the print medium 3 that has been transported by the transport belt 37.

  In order to pass the center line of the print medium 3 through the center of the fixing roller 23 (on the line segment AA ′ in FIG. 4) (when the size of the print medium 3 is A5, the lengths of e1 and e2 in FIG. 4 are equal. The print medium 3 is positioned on the conveyance belt 37 so that the center line of the print medium 3 coincides with the center line of the conveyance belt 37.

  In the fixing unit 22, the positioned printing medium 3 is passed between the fixing roller 23 and the pressure roller 24 heated by the halogen lamp 32. As a result, the unfixed toner on the print medium 3 is heated and fixed to the print medium 3.

  The print medium 3 heated and fixed by the fixing unit 22 is discharged onto the face down stacker 31 by a discharge roller 28 driven by a discharge roller 27 for conveying the print medium and a discharge roller 30 driven by the discharge roller 29.

Here, an outline of the present invention, that is, an outline of a procedure for predicting the printing speed before starting printing will be described.
When the printing speed is determined, the fixing temperature is also determined according to the paper size and printing conditions.

FIG. 7 is a graph showing printing efficiency with the left vertical axis representing the number of printed sheets, the right vertical axis representing the printing speed, and the horizontal axis representing time. (Paper size is A5, printing conditions are color printing)
When printing is initially performed at 30 ppm, and the printing speed is set again to 16 ppm due to a temperature rise in the non-sheet-passing portion and printing is continued, the number of prints is a line segment a1, and the printing speed is a line segment a2. The line number b1 and the printing speed are indicated by a line segment b2 when printing is performed at a printing speed of 24 ppm from the beginning to the end.
A section A in the figure is a transition section when the printing speed is reset.
As is apparent from this graph, the throughput is better when printing is performed at the same printing speed from the beginning to the end than when the printing speed is changed during printing.

FIG. 8 is a graph in which the vertical axis represents the number of printed sheets and the horizontal axis represents the roller end temperature.
FIG. 8 shows the relationship between the number of printed sheets at each printing speed and the end temperature based on the actual measurement value when the paper size is A5 and the printing condition is color printing.
In FIG. 8, the printable upper limit temperature of the end temperature is 200 ° C. Therefore, if the end temperature is 200 ° C. or higher, it is a non-printable region.

For example, when printing is performed at a printing speed of 30 ppm (fixing temperature of 180 ° C.) when the edge temperature is 180 ° C., as shown by the plot symbol ●, the edge temperature rises to 200 ° C., which is the maximum printable temperature. It can be seen that a maximum of 42 sheets can be printed.
Similarly, when printing is performed at a printing speed of 24 ppm (fixing temperature of 160 ° C.) when the edge temperature is 180 ° C., the edge temperature rises to 200 ° C., which is the maximum printable temperature, as indicated by the plot symbol ■. It can be seen that a maximum of 56 sheets can be printed.
Similarly, when printing is performed at a printing speed of 16 ppm (fixing temperature of 140 ° C.) when the edge temperature is 180 ° C., the edge temperature rises to 200 ° C., which is the maximum printable temperature, as indicated by the plot symbol Δ. It can be seen that printing of 115 sheets or more is possible.

  A printable sheet number prediction table for each printing speed when the paper size is A5 and the printing condition is color printing can be created from each plot code based on the actually measured values in FIG.

For example, in the case of a printing speed of 30 ppm (fixing temperature 180 ° C.), the number of printable sheets until the end temperature increases from 180 ° C. to 190 ° C. is the vertical axis corresponding to the horizontal axis 180 ° C. in the plot symbol ● in FIG. 17 sheets, which is the difference between the number of printed sheets of 8 and the number of printed sheets of 25 on the vertical axis corresponding to 190 ° C., are calculated, and the value is inserted into the corresponding cell of the printable sheet number prediction table.
Similarly, in order to obtain the number of printable sheets while the end temperature is increased from 190 ° C. to 200 ° C., the number of prints on the vertical axis corresponding to the horizontal axis 200 ° C. and the end temperature is 190 ° C. A difference of 25 sheets from the number of printed sheets of 25 is calculated and the value is inserted into the corresponding cell.

As described above, in the present invention, the printable sheet number prediction table is created by obtaining the number of printed sheets necessary to increase the 10 ° C. end temperature for every 10 ° C. end temperature from FIG.
That is, in the present invention, when the paper size is A5 and the printing condition is color printing, the printable sheet number prediction table with a printing speed of 30 ppm is referred to as Table A, and the printable sheet number prediction table with a printing speed of 24 ppm is referred to as Table B. The printable sheet number prediction table at a speed of 16 ppm is referred to as Table C.

9 shows a main part of the table A, FIG. 10 shows a main part of the table B, and FIG. 11 shows a main part of the table C.

例えば印刷開始前の端部温度が１８０℃だった場合、端部温度が印刷可能上限温度２００℃に達するまでの印刷可能最大枚数は印刷速度３０ｐｐｍの時、下式により、４２枚と算出される。

The maximum number of printable sheets is calculated as follows when the printing speed is 30 ppm.

For example, when the edge temperature before starting printing is 180 ° C., the maximum printable number of sheets until the edge temperature reaches the printable upper limit temperature 200 ° C. is calculated as 42 sheets according to the following formula when the printing speed is 30 ppm. .

(Description of operation of the first embodiment)
FIG. 5 is a flowchart of the first embodiment showing the flow of processing from the reception of print data to the end of printing.

Step S1-1
When receiving the print data, the data receiving unit 106 stores the print data in units of print jobs in the data storage unit 105, and then stores a “separated job” indicating a series of job separations in the data storage unit 105.
Here, the data storage unit 105 is a stack having a FIFO (first-in first-out) function. Therefore, the “separated job” is stored at the end of the data storage unit 105.

Step S1-2
The job determination unit 103 takes out and reads the first job stored in the data storage unit 105.

Step S1-3
The job determination unit 103 determines from the job data of the job whether the size of the medium to be printed is less than A4 width. If the medium size is A4 width, the process proceeds to S1-8. If the medium size is less than A4 width, the process proceeds to S1-4.

Step S1-4
The printable sheet number prediction unit 104 reads the number of prints of the first job from the job data.

Step S1-5
The printable sheet number predicting unit 104 reads the end temperature of the fixing roller 23 from the sub-thermistor 26 via the end temperature detecting unit 113.

Step S1-6
The printable sheet number predicting unit 104 determines a printing speed and a fixing temperature that are not changed during printing from the number of printed sheets of the read first job and the end temperature of the fixing roller 23.
Details of step S1-6 will be described separately in steps S1-21 to S1-32.

Step S1-7
The main control unit 101 notifies the printing control unit 107, the image formation control unit 108, and the fixing control unit 110 of the printing speed determined by the printable sheet number prediction unit 104.
The main control unit 101 notifies the fixing control unit 110 of the fixing temperature determined by the printable sheet number predicting unit 104, and proceeds to step S1-9.

Step S1-8
The main control unit 101 notifies the conveyance control unit 107, the image formation control unit 108, and the fixing control unit 110 of a predetermined printing speed (for example, 30 ppm) according to the job.
The main control unit 101 notifies the fixing control unit 110 of a target value of a predetermined fixing temperature according to the job.

Step S1-9
Each control unit prepares to drive the motor in accordance with the notified printing speed (for example, 30 ppm).
The fixing control unit 110 starts temperature control so that the notified fixing temperature target value (for example, 180 ° C.) is reached.

The main control unit 101 notifies the conveyance control unit 107 of the start of paper feed, and the conveyance control unit 107 feeds paper.
When the paper feeding is completed, the main control unit 101 notifies the image forming control unit 108, the conveyance control unit 107, and the fixing control unit 110 of the conveyance start.

Step S1-10
When the print medium 3 is conveyed to a predetermined position, the main control unit 101 notifies the image formation control unit 108 of an image output start instruction.
When notified of an image output start instruction, the image forming control unit 108 starts exposure of the exposure devices 18 to 21, and attaches toner to the electrostatic latent images formed by the image forming units 14 to 17 to perform image forming processing. I do.

Step S1-11
The fixing control unit 110 fixes the print medium 3 and the fixed print medium 3 is discharged out of the apparatus.

Step S1-12
The job determination unit 103 confirms the presence or absence of the next print data stored in the data storage unit 105.
If the “separated job” described in step S1-1 appears as the first job, it is confirmed that there is no print data to be printed in the data storage unit 105 having the FIFO (first-in first-out) function.
If there is still print data, the process proceeds to step S1-2, and if not, the process proceeds to step S1-13.

Step S1-13
The main control unit 101 causes the conveyance control unit 107 to stop the conveyance operation, and the printing process ends.

Next, details of step S1-6 will be described.
FIG. 6 is a detailed flowchart of step S1-6 of the first embodiment showing a flow of processing for determining process parameters based on the edge temperature data and the number of printed sheets when printing a job having a width less than A4.
In the present embodiment, the details of step S1-6 will be described with a sheet having a width less than A4 as A5 size and a printing condition as color.
FIG. 8 is a graph in which the vertical axis is the number of printed sheets and the horizontal axis is the end temperature when the paper is A5 size and the printing condition is color, and is used in the description of the flowchart of FIG.
Hereinafter, the operation of step S1-6 will be described in detail in the order of steps from step S1-21 to step S1-32.

Step S1-21
The printable sheet number predicting unit 104 determines whether or not the end temperature acquired from the sub-thermistor 26 via the end temperature detecting unit 113 is within the printable range (for example, 200 ° C.).
If the end temperature is outside the printable range, the process proceeds to step S1-22. If the end temperature is within the printable range, the process proceeds to step S1-25.

Step S1-22
Wait for a certain time (for example, 10 seconds) until the end temperature cools down.

Step S1-23
The printable sheet number predicting unit 104 determines whether the end temperature acquired from the end temperature detecting unit 113 is within a printable range (for example, 200 ° C.).
If the end temperature is outside the printable range, the process proceeds to step S1-22. If the end temperature is within the printable range, the process proceeds to step S1-24.

Step S1-24
The main control unit 101 notifies the fixing control unit 110 that the fixing temperature at the start of printing is set to a temperature (for example, 140 ° C.) at which the end temperature does not easily rise outside the printable range during printing.
The main control unit 101 notifies the conveyance control unit 107, the image formation control unit 108, and the fixing control unit 110 of a printing speed (for example, 16 ppm) corresponding to the above-described temperature (for example, 140 ° C.).

Step S1-25
The printable sheet number prediction unit 104 refers to the printable sheet number prediction table storage unit 116 with reference to a printable sheet number prediction table (table A) with a printing speed of 30 ppm when the sheet is A5 size and the printing condition is color. The maximum number of printable items from the temperature to the printable upper limit temperature is calculated.

例えば端部温度が１８０℃だった場合は以下のように算出する。

The maximum number of printable sheets is calculated as follows using Table A in FIG.

For example, when the end temperature is 180 ° C., the calculation is performed as follows.

Step S1-26
The maximum number of printable sheets is compared with the number of printed sheets of the job. If the maximum number of printable sheets is larger than the number of printed sheets of the job, the process proceeds to S1-27. If the maximum number of printable sheets is smaller than the number of printed sheets of the job, the process proceeds to S1-28.

Step S1-27
The main control unit 101 notifies the conveyance control unit 107, the image formation control unit 108, and the fixing control unit 110 of the printing speed (for example, 30 ppm).
In addition, the fixing control unit 110 is notified of a fixing temperature (for example, 180 ° C.) corresponding to the printing speed.

Step S1-28
From the printable sheet number prediction table storage unit 116, the printable sheet number prediction table 104 stores a printable sheet number prediction table (printing speed 24 ppm slower than 30 ppm when the sheet is A5 size, the printing condition is color, and the printing speed is step S1-25). Referring to the above-mentioned table B), the maximum printable number from the current end temperature to the printable upper limit temperature is calculated.

Step S1-29
The maximum number of printable sheets is compared with the number of printed sheets of the job. If the maximum number of printable sheets is larger than the number of printed sheets of the job, the process proceeds to S1-30. If the maximum number of printable sheets is smaller than the number of printed sheets of the job, the process proceeds to S1-31.

Step S1-30
The main control unit 101 notifies the conveyance control unit 107, the image formation control unit 108, and the fixing control unit 110 of the printing speed (for example, 24 ppm).
In addition, the fixing control unit 110 is notified of a fixing temperature (for example, 160 ° C.) corresponding to the printing speed.

Step S1-31
From the printable sheet number prediction table storage unit 116, the printable sheet number prediction table 104 stores a printable sheet number prediction table (printing speed 16 ppm slower than 24 ppm when the sheet is A5 size, the printing condition is color, and the printing speed is step S1-28). Referring to the above-mentioned table C), the maximum printable number from the current end temperature to the printable upper limit temperature is calculated.

Step S1-32
The maximum number of printable sheets is compared with the number of printed sheets of the job. If the maximum number of printable sheets is larger than the number of printed sheets of the job, the process proceeds to S1-24. If the maximum number of printable sheets is smaller than the number of printed sheets of the job, the process proceeds to S1-22.

  In this embodiment, as a representative example when the size of the medium to be printed is less than A4 width, the case where the size is A5 in color printing has been described. Naturally, the number of printed sheets and the edge temperature in monochrome printing or other sizes are described. Various tables created on the basis of the relation graph are also stored in the printable sheet number prediction table storage unit 116 described above, and the number of printed sheets obtained from the print job and the temperature sensor are obtained as in the present embodiment. Based on the edge temperature, it is possible to set a printing speed and a fixing temperature corresponding to the printing speed before starting printing on the medium using the table.

  In the present embodiment, when the size of the medium is less than the A4 width, the temperature of the end of the roller that increases in temperature corresponding to the number of sheets to be printed is always predicted before the start of printing, and can be changed during printing. The printing speed is set so that the user can select either the “narrow control mode” or the “normal control mode” on the operation panel 122, and the roller is set only when the “narrow control mode” is selected. The printing speed and the fixing temperature may be set in consideration of the temperature at which the edge of the ink increases.

(Description of the effect of Example 1)
According to this embodiment, the printing speed and fixing temperature at which the end temperature does not exceed the printable upper limit temperature during printing are set in advance before starting the printing of the job, so the printing speed can be changed during the printing of the job. It can be completed by printing at a constant speed.
That is, since the process parameters are not changed in the middle of the job, the effect of keeping the print quality constant while printing one print job can be obtained.

In this embodiment, when a plurality of jobs having the same printing conditions and the same paper size are mixed in a continuous job, these jobs are extracted and continuously printed, and the end temperature is printed during printing. Since the printing speed and the fixing temperature are set in advance at the start of printing so as not to exceed the upper limit temperature, the object is to keep the printing quality of the job constant without changing the printing speed during printing. In order to achieve such an object, the image forming apparatus according to the present embodiment is configured as follows.
(Description of Configuration of Example 2)
The configuration of this embodiment will be described with reference to FIGS. 2, 3, 4, and 12.
2, 3, and 4 are the same as those in the first embodiment, and a description thereof is omitted.

FIG. 12 is a functional block diagram of Embodiment 2 of the present invention.
As shown in FIG. 12, a printer 301 as an image forming apparatus includes a main control unit 201 that controls the printer 301, a process parameter setting unit 202 that sets process parameters in printing,
A data receiving unit 206 that receives a print job from the host device 123; a data storage unit 205 having a FIFO function in which the received print job is stored;
A job determination unit 203 that extracts and summarizes jobs having the same paper size and printing conditions from a plurality of jobs stored in the data storage unit 205 and confirms whether the paper size is less than A4;
A printable sheet number predicting unit 204 that obtains a detection value of the sub-thermistor 26 via the edge temperature detecting unit 213 and predicts a printable sheet number, an edge temperature at the start of printing, a sheet size, a printing condition, and a printing speed. A printable sheet number prediction table storage unit 216 that stores the number of printable sheets for each time and is used for prediction by the printable sheet number prediction unit 204;
When the received print job is a continuous job, it is used to retrieve from the data storage unit 205 a print job having the same paper size and printing conditions as the first job in the data storage unit 205 and re-store the print job. The same job storage unit 217;
A conveyance control unit 207 that controls a conveyance mechanism 214 including a conveyance belt 37, rollers 6 to 8 and 13, and discharge rollers 27 to 30, an image forming unit 14 to 17, exposure devices 18 to 21, and a transfer roller 9. The image forming control unit 208 that controls the image forming mechanism 215 configured by ˜12, the drive control unit 211 that controls the driving of the fixing roller 23 and the pressure roller 24, and the halogen lamp 32 based on the detection value of the main thermistor 25. A temperature control unit 212 that performs on / off control of the sensor, an end temperature detection unit 213 that performs detection of the sub-thermistor 26,
A fixing controller 210 that manages the drive controller 211, the temperature controller 212, and the end temperature detector 213;
A display unit 221 that is an LCD for displaying to the user, an operation panel 222 for inputting a setting value from the user, and the like.

(Description of operation of the second embodiment)
FIG. 13 is a flowchart showing a processing flow from the reception of the continuous job to the end of printing.
FIG. 14 is a diagram showing the contents of continuous jobs transmitted from the host apparatus in this embodiment in the order in which the apparatus inputs them.
FIG. 15 shows the job printing order based on the operation procedure of this embodiment, and FIG. 16 shows the contents of the same job storage unit 217 as the data storage unit 205 at the time of step S2-14 in FIG.
Hereinafter, steps S2-1 to S2-20 will be described in the order of steps while using FIG. 14 and FIG. 16 together.

Step S2-1
When the data receiving unit 206 receives the print data, the data receiving unit 206 stores the print data in the data storage unit 205, and then stores a “separated job” indicating a series of job separations in the data storage unit 205.
Here, the data storage unit 205 is a stack having a FIFO (first-in first-out) function. Therefore, the “separated job” is stored at the end of the data storage unit 205.

Step S2-2
The job determination unit 203 takes out the first job (color, A4 size, 10 sheets) stored in the data storage unit 205 and stores it in the same job storage unit 217.
Therefore, the first job stored in the data storage unit 205 having the FIFO function has been replaced with the second job input by the data receiving unit 206 (monochrome, A4 size, 5 sheets in input order 2 in FIG. 14). Become. Also, the job stored at the end of the data storage unit 205 is the “separated job”.
The job contents stored in the same job storage unit 217 include a job input order number, a printing condition (color or monochrome), a paper size, and the number of printed sheets.

Step S2-3
The job determination unit 203 checks whether a print job is still stored in the data storage unit 205. If it is stored, the process proceeds to step S2-4. If the “separated job” is in the first job, it is determined that there is no job to be printed, and the process proceeds to step S2-8.

Step S2-4
The job determination unit 203 checks whether or not the first job stored in the data storage unit 205 has the same printing conditions and paper size as the job stored in the same job storage unit 217. If they are the same, the process proceeds to step S2-5, and if not, the process proceeds to step S2-7.

Step S2-5
The job determination unit 203 is a specified value (for example, 40 sheets) in which the total number of prints of the job stored in the same job storage unit 217 as the print number of the first job stored in the data storage unit 205 is separately determined. ) Is reached. If not reached, the process proceeds to step S2-6, and if reached, the process proceeds to step S2-9.
This specified value can be freely set by the user from the operation panel 222, and when a plurality of jobs are present in the data storage unit, the number of prints to be continuously printed is stopped and divided into a plurality of groups for each group. Is used to maintain a constant print quality.

Step S2-6
The job determination unit 203 takes out the first job stored in the data storage unit 205, additionally stores it in the same job storage unit 217, and proceeds to step S2-3.

Step S2-7
The job determination unit 203 extracts the first job stored in the data storage unit 205, stores the job again in the data storage unit 205, and proceeds to step S2-3.

Step S2-8
The job determination unit 203 takes out the “separated job” stored in the data storage unit 205 and stores it again in the data storage unit 205.

Step S2-9
The job determination unit 203 determines whether the size of the printing medium stored in the same job storage unit 217 is less than A4 width. When the medium size is A4 width, the process proceeds to step S2-13. When the medium size is less than A4 width, the process proceeds to step S2-10.

Step S2-10
The printable sheet number predicting unit 204 reads the total print number of the job from the same job storage unit 217.

Step S2-11
The printable sheet number predicting unit 204 reads the end temperature of the fixing roller 23 detected by the sub-thermistor 26 via the end temperature detecting unit 113.

Step S2-12
The printable sheet number predicting unit 204 determines the target values of the printing speed and the fixing temperature from the total number of printed sheets of the job and the end temperature of the fixing roller 23, and then proceeds to step S2-14.
The details of step S2-12 are the same as steps S1-21 to S1-32 of the first embodiment shown in FIG.

Step S2-13
The main control unit 201 notifies the conveyance control unit 207, the image formation control unit 208, and the fixing control unit 210 of a predetermined printing speed (for example, 30 ppm) according to the A4 size printing paper.
The main control unit 201 notifies the fixing control unit 210 of the target value of the fixing temperature corresponding to the printing speed.

Step S2-14
Each control unit prepares to drive the motor in accordance with the notified printing speed (for example, 30 ppm).
The fixing control unit 210 starts temperature control so that the notified fixing temperature target value (for example, 180 ° C.) is reached.
Note that the contents of the data stored in the same job storage unit 217 as the data storage unit 205 when passing through this step are described in FIG.

The main control unit 201 notifies the conveyance control unit 207 of the start of paper feed, and the conveyance control unit 207 feeds paper.
When the paper feeding is completed, the main control unit 201 notifies the image forming control unit 208, the conveyance control unit 207, and the fixing control unit 210 of the start of conveyance.

Step S2-15
When the print medium 3 is conveyed to a predetermined position, the main control unit 201 notifies the image formation control unit 208 of an image output start instruction.
When notified of an image output start instruction, the image formation control unit 208 starts exposure of the exposure devices 18 to 21, and performs image formation processing by attaching toner to the electrostatic latent images formed on the image formation units 14 to 17. Do.

Step S2-16
The fixing control unit 210 fixes the print medium 3 and the fixed print medium 3 is discharged out of the apparatus.

Step S2-17
The job determination unit 203 deletes the job stored in the same job storage unit 217.

Step S2-18
The job determination unit 203 confirms whether a job is still stored in the data storage unit 205. If it is stored, the process proceeds to step S2-2. If the “separated job” is in the head job of the data storage unit 205, the process proceeds to step S2-19.

Step S2-19
The job determination unit 203 retrieves the “separated job” from the data storage unit 205 and stores it again in the data storage unit 205 having the FIFO function, and then proceeds to step S2-20.

Step S2-20
The job determination unit 203 confirms whether a job is still stored in the data storage unit 205.
If the job is still stored, the process proceeds to step S2-2. If the “separated job” is in the head job of the data storage unit 205, it is determined that all the received jobs are taken out from the data storage unit 205 and printed. The main control unit 201 causes the conveyance control unit 207 to stop the conveyance operation, and the printing process ends.
The reason why the same operation is performed in step S2-18 and step S2-20 is that when the step S2-9 is directly followed from step S2-5, a print job still exists at the end of the “separation job”. It is a measure to confirm because there is a possibility.

(Description of the effect of Example 2)
As described above, according to the present embodiment, in addition to the effects of the first embodiment, a plurality of jobs having the same printing conditions (the same printing conditions and the same medium size) are mixed in a continuous job. These jobs are extracted and collectively printed at the same printing speed, and the printing speed and fixing temperature are set in advance at the start of printing so that the end temperature does not exceed the upper printing limit temperature during printing. Therefore, printing can be performed at a constant speed without changing the printing speed during printing. That is, since the process parameters are not changed in the middle of printing, it is possible to obtain an effect that the print quality of jobs having the same printing conditions can be kept constant.

In the second embodiment, when there are a plurality of jobs with the same printing conditions in a continuous job, the print quality of the jobs with the same printing conditions is kept constant by extracting and collectively printing these jobs. Although the operation has been described, the purpose of this embodiment is to exclude a print job for A4 size paper from the extracted job target.
This is because printing on A4 size paper does not contribute to an increase in the temperature at the end of the roller. Therefore, it is possible to input a print job on A4 size paper as a sort target. This is because there is a high probability that printing will be performed with an unnecessarily disturbed order.
In order to achieve such an object, the image reading apparatus according to the present embodiment is configured as follows.

(Description of Configuration of Example 3)
The configuration of this embodiment will be described with reference to FIGS. 2, 3, 4, and 12.
The configuration of FIGS. 2, 3, 4 and 12 is the same as that of the second embodiment, and the description thereof is omitted.

(Description of operation of the third embodiment)
FIG. 14 is a diagram showing the contents of the continuous job transmitted from the host device in the order of input by this device, which is used in the second embodiment, but is also used in this embodiment.
FIG. 17 is a flowchart showing a processing flow from the reception of the continuous job to the end of printing.
Only the differences from FIG. 13 will be described below from step S2-1 to step S2-20 in FIG.

Since step S2-9 in FIG. 13 of the second embodiment has disappeared, the flow from step S2-5 and step S2-8 that should proceed to step S2-9 directly proceeds to step S2-10 in FIG. .
Further, in FIG. 17, step S3-1 is newly inserted between step S2-2 and step S2-3. The operation of step S3-1 is described below.

Step S3-1
The job determination unit 203 determines whether the medium size of the print job extracted from the data storage unit 205 and stored in the same job storage unit 217 is less than the A4 width. When the medium size is A4 width, the process proceeds to step S2-13, and when it is less than the A4 width, the process proceeds to step S2-3.

FIG. 18 shows a print order of jobs executed based on the operation procedure of this embodiment.
Compared with FIG. 15 showing the printing order of the second embodiment, in FIG. 18, it can be seen that A4 size paper jobs are extracted and excluded from the target of continuous printing, and are printed in the order received from the host device.
It should be noted that the user can also use the operation panel 222 to select and specify which of the second and third embodiments the apparatus performs.

(Description of the effect of Example 3)
As described above, when multiple jobs with the same printing conditions are mixed in a continuous job, the print quality of jobs with the same printing conditions is kept constant by extracting these jobs and printing them continuously at the same printing speed. In addition to the effect of the second embodiment that the image can be held, according to the present embodiment, it is possible to add the print job to be printed on the A4 size paper to the A4 size paper by excluding the print job to be printed on the A4 size paper. There is an effect that it is possible to prevent the printing job from being unduly delayed compared to a job that prints on a sheet of another size.

In the description of the above embodiment, a printer having the maximum width capable of passing paper as an A4 size has been described as an example. However, the present invention is also applicable to image forming apparatuses having a maximum width of other sizes such as A3, B4, and A5.
In the description of the above embodiment, a job in which a target print job is received from a higher-level device has been described as an example. However, the present invention can also be applied to a job obtained by copying as one of the functions of this device. .

1 is a functional block diagram of an image forming apparatus of the present invention (Example 1). Sectional drawing of a printer. Schematic of an image forming unit. Schematic of the fixing unit. FIG. 3 is a flowchart showing the flow of processing according to the first embodiment. The flowchart figure of step S1-6 of Example 1. FIG. 6 is a graph showing printing efficiency with the left vertical axis representing the number of printed sheets, the right vertical axis representing the printing speed, and the horizontal axis representing time. A graph in which the vertical axis represents the number of printed sheets and the horizontal axis represents the roller end temperature. Table A (End temperature prediction table with printing speed of 30 ppm) Table B (End temperature prediction table for 24 ppm printing speed) Table C (edge temperature prediction table with a printing speed of 16 ppm) FIG. 3 is a functional block diagram of an image forming apparatus according to the present invention (Example 2). The flowchart figure which shows the flow of a process of Example 2. FIG. The contents of the job sent from the host device. The print order of jobs after sorting in the second embodiment. The figure which shows the content stored in each memory | storage part at the time of step S2-14 of Example 2. FIG. FIG. 9 is a flowchart showing the flow of processing according to the third embodiment. Printing order of jobs after sorting in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 23 Fixing roller 24 Pressure roller 25 Main thermistor 26 Sub thermistor 101 Main control part 102 Process parameter setting part 103 Job determination part 104 Printable sheet number estimation part 105 Data storage part (FIFO)
DESCRIPTION OF SYMBOLS 106 Data reception part 107 Conveyance control part 108 Image formation control part 110 Fixing control part 111 Drive control part 112 Temperature control part 113 End part temperature detection part 114 Conveyance mechanism 115 Image formation mechanism 116 Printable sheet number prediction table storage part 121 Operation panel 122 Input unit 123 Host device

Claims (6)

A data storage unit for storing image formation data in units of print jobs;
An image forming mechanism for forming an image on a medium corresponding to the image forming data;
A fixing unit having a fixing roller and thermally fixing the medium;
In an image forming apparatus comprising:
The fixing unit further includes an end temperature detecting unit that detects the temperature of the end of the fixing roller,
A job determination unit that determines from the image formation data whether or not the sheet passing width of the medium of the print job is the maximum width that can be passed through the apparatus;
When the determination result of the job determination unit is NO, the temperature of the end of the fixing roller detected by the end temperature detecting unit, the number of prints of the print job, the printing condition on the medium, and the fixing roller A main control unit that presets the image forming speed of the print job based on the printable upper limit temperature at the end;
And the image forming mechanism starts image formation of the print job at a set image forming speed.   The image forming apparatus according to claim 1, wherein a fixing temperature of the fixing unit is also set in advance before image formation according to the set image forming speed, the size of the medium, and a printing condition on the medium.   The set image forming speed is a combination of a plurality of combinations in which the temperature at the end of the fixing roller reaches the maximum printable upper limit temperature before completion of image formation for a predetermined number of images of the print job. It is the fastest image forming speed after judging from the combination of image forming speed and fixing temperature based on the temperature at the end of the fixing roller at the start of image forming and the predetermined number of image forming. The image forming apparatus according to claim 1, wherein the image forming apparatus is selected on the condition.   When the image formation data is a continuous job and a plurality of print jobs having the same printing conditions and the same size are mixed, the corresponding print job can be continuously processed by sorting before image formation. The combination of the image forming speed and the fixing temperature is set for the print job based on the total number of images formed for the print job, and the image is formed with the set combination of the image forming speed and the fixing temperature. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The print job is divided into a plurality of groups so that the sum of the number of image formation sheets of the same size print job under the same print condition does not exceed a certain number, and the image formation speed is set for each group. 5. The image forming apparatus according to claim 4, wherein the image is formed.   The image forming apparatus according to claim 4, wherein the print job to be sorted is limited to a print job in which a sheet passing width of the print job is less than a maximum width that can be passed to the apparatus.

Images