JP2012141404A - Image forming apparatus and temperature control method for fixing device of the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fixing failure even if the power supplied to a fixing unit is reduced by performing a post process such as punching and stapling in an image forming apparatus with an upper limit of the power consumption specified.SOLUTION: When a print mode for a new print job is obtained (Yes for step S4), a target temperature of temperature control of the fixing unit necessary for performing the print job is determined (step S5). In this event, it is determined whether or not an additional process, such as punching and stapling, generating a load causing reduction in the power to be supplied to the fixing unit is included in the print job. A first temperature is determined as the target temperature if no additional process is included, and a second temperature higher than the first temperature is determined as the target temperature if an additional process is included in the print job. A control unit performs a warm-up control based on the determined target temperature (step S9)

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for controlling the temperature of a fixing member in a fixing device of the image forming apparatus.

  In an electrophotographic image forming apparatus, the surface of a photoreceptor is uniformly charged by a charger, and then the charged photoreceptor surface is scanned with a laser beam to form an electrostatic latent image. The image is visualized by supplying toner from the developing unit. The toner image carried on the surface of the photosensitive member in this way is transferred onto the recording sheet via the intermediate transfer member or directly, and then further heated and pressurized by the heating rotator in the fixing device, and then the toner. The image is thermally fixed on the recording sheet.

Such image forming apparatuses include an image reading apparatus provided with an automatic document conveying apparatus that reads an image while conveying originals one by one, and a recording sheet output from the image forming apparatus after punching or stapling. An optional device such as a post-processing device (finisher) that performs processing may be connected and used.
Normally, these optional devices, particularly post-processing devices, have a dedicated power supply unit connected to a commercial power outlet, but recently, in order to reduce manufacturing costs, the power supply unit has been omitted, and the connection destination image has been omitted. A configuration in which power is supplied from a power supply unit of the forming apparatus main body is considered.

On the other hand, the upper limit of power consumption in the image forming apparatus is voluntarily determined by each manufacturer from the viewpoint of energy saving. If the power unit is shared with the optional device as described above, the power, particularly the power supplied to the fixing device is reduced. Insufficient fixing may occur.
Therefore, for example, in Patent Document 1, when it is detected that the post-processing device is attached to the image forming apparatus main body, a temperature (hereinafter referred to as “target”) that is automatically a temperature control target at the time of fixing of the fixing device. The temperature is called “temperature”) by a predetermined amount higher than the normal fixing temperature.

  In this way, a sufficient amount of heat can be accumulated in the fixing roller and the pressure roller in the fixing device, so that the fixing failure does not occur even if power is temporarily insufficient for driving the post-processing device. Yes.

JP 2005-17737 A

However, in the above-described prior art, the temperature control of the fixing device is always performed at a high target temperature simply because the optional device is connected, and thus wasteful power is consumed, which is contrary to energy saving.
The present invention has been made in view of the above circumstances, and is a case where power supplied to the fixing device is reduced by performing additional processing such as post-processing while suppressing an increase in power consumption in the fixing device. The present invention relates to an image forming apparatus capable of preventing occurrence of fixing failure even if there is a fixing device temperature control method executed by the image reading apparatus.

  In order to achieve the above object, an image forming apparatus according to an aspect of the present invention uses a fixing member heated by a heating unit in a fixing device after transferring a toner image carried on an image carrier onto a recording sheet. An image forming apparatus for heat fixing, wherein a determining unit that determines a target temperature that the fixing member should reach when an image forming job is executed, and the heating unit is controlled so that the temperature of the fixing member becomes the determined target temperature And a temperature control unit that determines whether or not an additional process for generating a load that causes a reduction in power to be supplied to the heating unit is specified in the image forming job to be executed. When the additional process is not designated, the first temperature is set as the target temperature, and when the additional process is designated, the second temperature higher than the first temperature is set as the target temperature. Special It is set to.

  According to another aspect of the present invention, there is provided a temperature control method for a fixing device in an image forming apparatus, wherein a toner image carried on an image carrier is transferred onto a recording sheet and then heated by a heating unit in the fixing device. A method for controlling a temperature of a fixing device in an image forming apparatus that performs heat fixing with a fixed fixing member, the step of determining a target temperature that the fixing member should reach when an image forming job is executed, and the temperature of the fixing member being determined And a temperature control step for controlling the heating means so as to achieve a set target temperature, wherein the determining step generates a load that causes a reduction in power to be supplied to the heating means in an image forming job to be executed. It is determined whether or not the additional process to be specified is specified. If the additional process is not specified, the first temperature is set as the target temperature and the additional process is specified. Expediently, and determines the greater than the first temperature the second temperature as the target temperature.

As described above, in the image forming job, the heating unit in the fixing unit is used only when an additional process that causes a reduction in the power to the heating unit of the fixing device and may cause a fixing failure is specified. Since the control target temperature is set to a second temperature higher than the normal first temperature, it is possible to avoid fixing failure while avoiding unnecessary power consumption in the fixing device.
Here, a post-processing device connected to the image forming apparatus main body and sharing the power supply unit with the image forming apparatus main body may be provided, and the additional processing may be post-processing executed by the post-processing device.

In addition, an acquisition unit that acquires a power load index value that indicates a degree of load that causes a reduction in power to be supplied to the heating unit by executing the additional process, and the power load index value corresponds to the additional process. If the load amount is less than a preset load amount, the determining unit may include a prohibiting unit that prohibits the determining unit from determining the target temperature as the second temperature.
Here, the additional processing is punching processing for forming punch holes in a recording sheet on which image formation has been performed, and the power load index value is the number of images formed in an image forming job to be executed, and the prohibiting unit If the number of image formations is less than the predetermined number, the determination unit may prohibit the determination of the target temperature to the second temperature.

  Here, the addition process is a stapling process for stapling the image-formed recording sheet part by part, and the power load index value constitutes a part of each image forming job to be executed. The number of recording sheets and the number of copies thereof, and the prohibiting means determines the determination means, except for the case where the number of each part is not more than a first threshold and the number of copies is not less than a second threshold. However, it may be prohibited to determine the target temperature as the second temperature.

  Further, the additional processing is a composite post-processing for performing stapling for stapling the recording sheet one by one after executing punch processing for forming punch holes in the recording sheet on which image formation has been performed, and the power The load index value is the sum of the total number of images formed in the image forming job to be executed and the number of copies to be stapled, and the prohibiting unit determines that when the power load index value is less than a predetermined value, The determination unit may prohibit the determination of the target temperature as the second temperature.

Receiving means for receiving an image forming job from an external terminal via a network;
Data conversion means for converting image data in the accepted image forming job into data in a format capable of image formation, and prior to determination of the target temperature by the determination means, data conversion by the data conversion means is started. It may be.
Further, when the next second image forming job is received during execution of the preceding first image forming job, the temperature control unit determines that the target temperature for the second image forming job is the second in the determining unit. When the target temperature in the first image forming job currently being executed is the first temperature, the target temperature is set to the second target temperature during the execution of the first image forming job. The temperature may be controlled by switching.

1 is a schematic diagram illustrating an overall configuration of a multifunction peripheral according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a fixing unit in the multifunction machine. It is a block diagram which shows the structure of the control part of the said multifunctional device. It is a figure which shows the structure of the power supply part in the said multifunctional device. It is a flowchart which shows the content of the temperature control process of the fixing | fixed part by the said control part. It is a flowchart which shows the subroutine of the target temperature determination process in step S5 of the flowchart of FIG. It is a flowchart which shows the subroutine which concerns on the modification of the target temperature determination process in step S5 of the flowchart of FIG. It is a flowchart which shows the modification of the said temperature control process. It is a flowchart which shows another modification of the said temperature control process.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described by taking a multifunction peripheral (MFP) having a plurality of functions such as a copy function, a printer function, and a scanner function as an example.
(1) Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic diagram showing the overall configuration of a multifunction peripheral 100 according to the present embodiment.

  The multi-function machine 100 includes an image forming apparatus main body 110 connected to an image reading apparatus 120 and a post-processing apparatus 130 as optional apparatuses. Based on a document image read by the image reading apparatus 120, the image forming apparatus main body 110 records a recording sheet. In addition to a copy function for forming an image on the printer, a printer function for receiving a print job from an external terminal via a network such as a LAN and outputting (printing out) a recording sheet on which an image is formed by the image forming apparatus main body 110, an image reading apparatus It has a scanner function for storing the document image read at 120 in an internal memory or transmitting it to an external terminal designated in advance.

  The image reading device 120 includes an automatic document feeder (ADF) 121, and the documents placed on the document tray 121 a are not shown one by one by operating the operation panel 70 provided in the image forming apparatus main body 110. The document is transported to the document reading position, the document is read by the CCD sensor 122, image data is generated, and the image data is transmitted to the control unit 50 of the multifunction machine main body 110. These document reading operations are controlled by the document reading control unit 123.

  The image forming apparatus main body 110 forms an image on a recording sheet by a known electrophotographic method, and includes an image process unit 10, an intermediate transfer unit 20, a paper feeding unit 30, a fixing unit 40, and a control unit 50. And selectively execute color and monochrome printing based on image data of the document read by the image reading device 120 or a print job received from an external terminal device (not shown) via a network (for example, LAN) To do.

The image processing unit 10 includes image forming units 10Y to 10K corresponding to development colors of yellow (Y), magenta (M), cyan (C), and black (K).
For example, the image forming unit 10Y includes a photosensitive drum 11, a charger 12, an exposure unit 13, a developing unit 14, a primary transfer roller 15, a cleaner 16, and the like disposed around the photosensitive drum 11.
The charger 12 charges the peripheral surface of the photosensitive drum 11 that rotates in the direction indicated by the arrow A.

The exposure unit 13 exposes and scans the charged photosensitive drum 11 with laser light to form an electrostatic latent image on the photosensitive drum 11.
The developing unit 14 contains a developer containing toner, and develops the electrostatic latent image on the photosensitive drum 11 with the toner, whereby a Y toner image is formed on the photosensitive drum 11.
The primary transfer roller 15 transfers the Y toner image on the photosensitive drum 11 onto the intermediate transfer belt 21 by electrostatic action. The cleaner 16 cleans residual toner remaining on the photosensitive drum 11Y after transfer.

The other image forming units 10M to 10K have the same configuration as the image forming unit 10Y except that the toner color is different, and the reference numerals are omitted in FIG.
The intermediate transfer unit 20 includes an intermediate transfer belt 21 that is stretched around a driving roller 24 and a driven roller 25 and circulates in an arrow direction.
When color printing (color mode) is executed, a corresponding color toner is formed on the photosensitive drum 11 for each of the image forming units 10Y to 10K, and each of the imaged toner images is intermediately transferred. Transferred onto the belt 21. The image forming operation for each of the colors Y to K is performed from the upstream side to the downstream side in the running direction of the intermediate transfer belt 21 so that the toner images of the respective colors are transferred in an overlapping manner at the same position of the running intermediate transfer belt 21. Are executed at different timings.

The paper feeding unit 30 feeds the recording sheets S from the paper feeding cassette one by one in accordance with the above image forming timing, and directs the fed recording sheets S toward the secondary transfer roller 22 via the conveyance path 31. Transport.
When the recording sheet S conveyed to the position of the secondary transfer roller 22 passes between the secondary transfer roller 22 and the intermediate transfer belt 21, each color toner image formed on the intermediate transfer belt 21 is secondary. Secondary transfer is collectively performed on the recording sheet S by the electrostatic action of the transfer roller 22.

The recording sheet S after each color toner image is secondarily transferred is conveyed to the fixing unit 40 and heated and pressed in the fixing unit 40, so that the toner image on the surface is fused to the surface of the recording sheet S. To be fixed.
When black only printing (monochrome mode) is executed, only the black image forming unit 10K is driven, and the process of charging, exposing, developing, and secondary transfer for black is performed by the same operation as described above. After that, the image is fixed by the fixing unit 40.

The recording sheet fixed by the fixing unit 40 is sent to the post-processing device 130 via the paper discharge roller 32 and the intermediate conveyance unit 33.
The post-processing device 130 includes a punch processing unit 131 that opens punch holes one by one in the recording sheet output from the image forming apparatus main body 110 by operating the operation panel 70 or an instruction from an external terminal, and a plurality of designated recordings. A staple processing unit 132 that staples a sheet as one copy and a post-processing control unit 133 that controls the operation of each unit in the post-processing apparatus 130 are provided.

These punch processing and stapling processing are performed as addition processing of a copy job or print job in response to an operation on the operation panel 70 or an instruction from an external terminal. Hereinafter, modes for punching or stapling at the time of print output are referred to as “punch mode” and “staple mode”, respectively.
An operation panel 70 is disposed at a position on the front side and the upper side of the image forming apparatus main body 110 that is easy for the user to operate. The operation panel 70 includes buttons for receiving various instructions from the user, a touch panel type liquid crystal display unit, and the like. The received instruction content is transmitted to the control unit 50, or information indicating the state of the MFP 100 is displayed. Display on the LCD.

  The control unit 50 of the image forming apparatus main body 110 performs temperature control of the fixing unit 40 based on the received image data of the job and also controls the operation of each part of the image forming apparatus main body 110 to execute a smooth image forming operation. As necessary, various print modes are executed in cooperation with the image reading device 120, the image reading control unit 123 in the post-processing device 130, and the post-processing control unit 133.

FIG. 2 is a schematic cross-sectional view illustrating the configuration of the fixing unit 40 of the multifunction peripheral 100.
In the present embodiment, a known electromagnetic induction type is used as the fixing unit 40, and an endless fixing belt 41 is stretched around the first roller 42 and the second roller 43, and an unillustrated attachment is provided. The nip portion N is formed by pressing the pressure roller 44 against the second roller 43 via the fixing belt 41 by the biasing mechanism.

An exciting coil 45 is held by a coil bobbin 46 along the upper peripheral surface of the first roller 42, and a high-frequency current is passed through the exciting coil 45 to generate a high-frequency magnetic field. The first roller 42 is configured to be induction-heated.
The temperature of the peripheral surface of the first roller 42 is detected by a temperature sensor 48 such as a thermistor, and the control unit 50 controls the power supply to the exciting coil 45 based on the detection result, and the first roller 42 and the fixing belt. 41 is controlled to reach a predetermined target temperature.

The second roller 43 (or pressure roller 44) is rotationally driven by a drive source (not shown), and the recording sheet S passes through the nip portion N and is thermally fixed.
(2) Configuration of Control Unit 50 FIG. 3 is a block diagram showing the configuration of the control unit 50.
As shown in the figure, the control unit 50 includes a CPU 51, a communication I / F (interface) unit 52, an image processing unit 53, an image memory 54, a laser diode driving unit 55, a ROM 56, a RAM 57, and an EEPROM 58.

The communication I / F unit 52 is a LAN card or a LAN board for connecting a LAN with an external terminal. The communication I / F unit 52 receives image data in a print job received from the external terminal via the LAN and sends it to the CPU 51.
The image processing unit 53 converts the image data received from the external terminal into a format suitable for image formation (bitmap development), and converts the BGR image data into CMYK image data of the development color. Known image processing such as color conversion is performed and stored in the image memory 54 for each page.

Based on an instruction from the CPU 51, the laser diode driving unit 55 reads out image data of each development color, drives the laser diode in the exposure unit 13 in each of the image forming units 10Y to 10K, and exposes and scans the photosensitive drum 11. Then, an image is formed on the recording sheet by the above-described procedure.
The ROM 56 stores a program for controlling the operation of each unit in the multifunction peripheral 100, a temperature control program for the fixing unit 40 to be described later, and a threshold value used when each program is executed. .

The RAM 57 is a volatile memory and serves as a work area when the CPU 51 executes a program.
The EEPROM 58 is a recordable non-volatile memory, and stores an accumulated value of the number of printed sheets, a set target temperature, and the like.
The power supply unit 60 is connected to a commercial power supply of 100 V, and supplies necessary power to the image forming apparatus main body 110, the image reading apparatus 120, and the post-processing apparatus 130.

  FIG. 4 shows a schematic configuration of the power supply unit 60. As shown in the figure, the power supply unit 60 is connected to an AC 100V commercial power supply P, detects a current value of the AC current, and a fuse 61 that prevents the excessive current from flowing and protects the circuit. A current transformer 62; a voltmeter 63 for detecting an AC voltage; a rectifier circuit 64 for converting AC to DC; an excitation coil 45; a capacitor 65 constituting an LC resonance circuit; and an IGBT (insulated) as a switch element. A gate bipolar transistor) 66, an IGBT drive circuit 67 for applying a drive voltage to the gate thereof, and a commercial power supply P converted into a predetermined voltage so that each part of the image forming apparatus main body 110, the image reading apparatus 120, A transformer circuit 68 for supplying electric power necessary for driving the post-processing device 130 is provided.

  The CPU 51 monitors the power consumption based on the detection results of the current transformer 62 and the voltmeter 63. If the power consumption exceeds a predetermined value (for example, 1500 W), the CPU 51 instructs the IGBT drive circuit 67. Thus, the duty ratio of the current flowing through the exciting coil 45 is reduced, and the power consumption in the fixing unit 40 is reduced. Thus, even when post-processing in the post-processing device 130 is executed and a large amount of power is used, the maximum power consumption set for the image forming apparatus main body 110 is not exceeded.

  The CPU 51 reads a necessary program from the ROM 56 and controls each part of the image forming apparatus main body 110 to form an image, and at the same time, the image reading control part 123 of the image reading apparatus 120 and the image reading control part 123 of the post-processing apparatus 130. To control the timing of operations of the image reading device 120 and the post-processing device 130, respectively, and smoothly execute various print modes.

Here, the print mode is a generic term for a mode including a copy process and a print process, and including various additional processes that are executed in association with the copy process, and is output from the image forming apparatus main body 110, for example. This includes a punch mode for punching a recorded sheet, a staple mode for performing a staple process, and the like.
Further, the CPU 51 controls the power supplied from the power supply unit 60 to the exciting coil 45 based on the detection signal of the temperature sensor 48 that detects the surface temperature of the first roller 42 in the fixing unit 40, so that the first roller 42 is predetermined. Finally, the temperature of the fixing belt 41 is controlled to a fixable temperature by setting the target temperature to the target temperature, and the power consumption is monitored as described above, and the power consumption of the entire multifunction peripheral 100 is set to the maximum power consumption set in advance. Control not to exceed.

Hereinafter, controlling the fixing belt 41 to be maintained at a predetermined target temperature is referred to as “temperature control”.
(3) Temperature Control Process of Fixing Unit 40 FIG. 5 is a flowchart showing the contents of the temperature control process of the first roller 41 in the fixing unit 40 executed by the control unit 50, and controls the entire multifunction peripheral 100. It is executed as a subroutine of a flowchart (not shown).

  First, it is determined whether a warm-up start condition is satisfied (step S1). As the warm-up start conditions, in this embodiment, the image forming apparatus main body 110 is turned on, the input operation is performed from the operation panel 70 in the power saving mode (sleep mode), and the maintenance door of the image forming apparatus main body 110 is closed. When any one of the print job acceptances from the external terminal occurs, it is determined that the warm-up start condition is met, but if the event is likely to start the print job immediately Not limited to this.

The maintenance door is opened when jamming or replacement of consumables such as a toner bottle, and the opening / closing operation is detected by an opening / closing switch such as a limit switch.
If it is determined in step S1 that any one of the warm-up start conditions is satisfied (YES in step S1), the IGBT drive circuit 67 of the power supply unit 40 is controlled to maximize the ON duty ratio of the fixing unit 40. A high frequency current is supplied to the exciting coil 45 to start warm-up (step S2).

  At this time, the target temperature to be reached on the surface of the first roller 42 is set to the first temperature to be normally set in the temperature range necessary for fixing (when the post-processing is not included in the print mode). The target temperature is specifically set to 160 ° C. in this embodiment (step S3). This temporarily set value is read from the ROM 56 and stored in the RAM 57 or the like.

When a new print job or copy job is received during warm-up, it is determined whether or not the print mode has been acquired (step S4).
If a new print job is received from an external terminal, the information on the print mode specified in the print job can be acquired from the control information included in the header. If a new copy job is received, the print mode can be acquired based on the input information from the operation panel 70 (hereinafter, “print job” is an image in the image forming apparatus main body 110). (It is assumed that a job with a forming operation is a generic term and includes a copy job in addition to an original print job received from an external terminal.)

  If it is determined in step S4 that a new print mode has not been acquired, the determination of whether or not a new print mode has been acquired is repeated until the provisionally set first temperature is reached (NO in step S11). In step S4), if the first temperature is reached without acquiring a new print mode (NO in step S4, YES in step S11), temperature control is performed to maintain the target temperature, and a print job is received. The standby state is entered (step S9).

If it is determined that a new print mode has been acquired (YES in step S4), the target temperature that the first roller 42 should finally reach is determined based on the content of the acquired print mode. (Target temperature determination process) (step S5).
FIG. 6 is a flowchart showing a subroutine of the target temperature determination process.
First, it is determined whether or not a print job to be executed includes a punch designation (step S101).

If the print mode includes punch designation (YES in step S101), it is determined whether the number of prints in the print job is N or more (step S102).
Since the punch unit 131 of the post-processing device 130 is executed for each recording sheet, the greater the number of prints, the greater the number of punch processes, and the unit to be supplied to the fixing unit 40 by the power required to drive the punch unit 131. The power per hour is reduced and the heating capacity is reduced. For this reason, in the second half of continuous printing, the temperature of the fixing belt 41 is lowered due to heat absorption by the recording sheet and may become lower than the fixing possible temperature, resulting in fixing failure. In this case (YES in step S102), the target temperature is set in advance to a second temperature (165 ° C. in the present embodiment) that is within a temperature range in which good fixing can be performed and is higher than the first temperature by a predetermined temperature. (Step S103).

The threshold value “N” is specifically determined by the heating capacity of the fixing unit 40 of the applicable model, the power consumption per punching process in the punching unit 131 of the post-processing device 130, and the like. In the present embodiment, as an example, N = 10 is set.
Conversely, if the number of prints is less than N (NO in step S102), sufficient fixing can be achieved without increasing the target temperature, so the target temperature is determined as the first temperature (step S106).

In step S101, if the print job is not designated for punching (NO in step S101), it is determined whether the print job includes a staple designation (step S104).
In this stapling designation, the unit number of sheets of one copy (the number of sheets to be bound in one stapling process) and the number of copies are designated in advance, and the smaller the number of copies of one copy, the larger the number of copies, Since the frequency and frequency of processing increase, so much power is consumed within a unit time, and power supply to the fixing unit 40 is reduced.

Therefore, when stapling is designated as the print mode (YES in step S104), when the number of copies as a unit of the staple processing is M or less and the number of copies is K or more. (YES in step S105), the process proceeds to step S103, and the target temperature is determined to be the second temperature.
On the other hand, if it is determined in step S105 that “the number of copies of one copy as a unit of stapling processing is not more than M and the number of copies is not less than K”, that is, the number of copies of one copy exceeds M, or If the number of copies is less than K (NO in step S105), sufficient fixing can be achieved without previously increasing the target temperature, so the target temperature is determined as the first temperature (step S106).

It should be noted that the values for the M sheets and the K portion, which are threshold values, are also determined as appropriate depending on the heating capacity of the fixing unit 40 of the applicable model, the power consumption per staple processing in the staple unit 132 of the post-processing device 130, and the like. . In this embodiment, M = 5 and K = 5 are set as an example.
Thus, the target temperature determination process is terminated, and the process returns to the flowchart of FIG.

  In step S6 of FIG. 5, the content determined in the target temperature determination process of step S5 is confirmed. If the determined target temperature is the second temperature (YES in step S6), the first value is determined in step S3. The target temperature temporarily set as the temperature is changed to the second temperature (step S7). Conversely, if the determined target temperature is not the second temperature (NO in step S6), the target temperature for warm-up is set. The first temperature temporarily set in step S3 is set as the main setting (step S10). These target temperature set values are stored in the RAM 57 or the EEPROM 58.

Thereafter, the control waits until the temperature of the first roller 42 reaches the target temperature (NO in step S8). If it reaches (YES in step S8), temperature control is performed to maintain the target temperature (step S9). ).
Then, the process returns to the main flowchart (not shown), and each unit is controlled to execute the received print job. However, when there is a possibility that fixing failure may occur due to the load due to punching or stapling as described above. Is set in advance to a second temperature higher than the first temperature, which is a normal fixing temperature, and the heat is stored in the first roller 42, the second roller 43, the pressure roller 44, etc. in the fixing unit 40. Therefore, there is no possibility that the fixing belt 41 becomes below the fixing temperature even if a certain number of sheets are continuously printed while executing predetermined post-processing.

Moreover, since the target temperature is set high only in a specific case where there is a possibility that fixing failure may actually occur, when the target temperature is always set high when the post-processing device is connected as in the conventional case. Compared to energy saving.
Regardless of whether or not the target temperature is determined to be the second temperature in step S5, after the target print job is completed, temperature control is performed using the first temperature as the target temperature (standby state). . This is because there is no point in maintaining the second temperature for the purpose of preventing a fixing failure as long as the print job is completed.

If a new print job is received while in the standby state, steps S4 to S10 are executed, and the print job is executed after controlling the temperature to the newly determined target temperature. What should I do?
In a standby state, when the MFP 100 does not accept a print job from an external terminal or the operation panel 70 is not operated at all for a predetermined time, the control unit 50 causes the fixing unit 40 to The mode is switched to a sleep mode that minimizes power consumption including the power to be supplied, and then warm-up is started when the warm-up start condition in step S1 is satisfied.

<Modification>
As described above, the present invention has been described based on the embodiments. However, the technical scope of the present invention is not limited to the above-described embodiments, and various modifications may be considered as follows. it can.
(1) In the above embodiment, the case where the punching process and the stapling process are alternatively executed as a process for generating a load that causes a fixing failure has been described in the flowchart of the target temperature determination process in FIG. In the present modification, a case will be described in which punching is performed and a stapling mode (punch / staple mode) can be specified.

  In this modification, the value indicating the amount of load on power when the punch / staple mode is executed (hereinafter referred to as “power load index value”) is the number of prints in one job and the number of copies in one job. Is defined as the sum of In the above embodiment, the power load index value in the punch mode is “number of prints”, and the power load index value in the staple mode is evaluated by “the number of copies and the number of copies”. The power load index value can also be the sum of them, but since the load amount of punch processing executed for each page occupies a large weight of the power load index value, in this modification, the number of prints is mainly used. The power load index value is obtained by adding the number of copies (the number of staples in one job) to this.

FIG. 7 is a flowchart showing the contents of the target temperature determination process in the present modification.
First, in step S201, it is determined whether or not a print job to be executed includes designation of a punch / staple mode.
If the print mode includes the designation of punch / staple mode (YES in step S201), the power load index value L in the punch / staple mode is calculated as described above (step S202). If the value of the power load index value L is equal to or greater than the predetermined value H (YES in step S203), the target temperature is determined to be the second temperature, assuming that there is a possibility of causing a fixing failure ( Step S204).

If the power load index value L is less than the predetermined value H in step S203 (NO in step S203), there is no possibility of fixing failure, so the target temperature is determined as the first temperature (step S205). ).
If no punch / staple mode is specified in the print job in step S201 (NO in step S201), whether or not the punch mode and the staple mode are specified in steps S206 to S211 and the power load in each process. The target temperature determination process based on the index value is performed. Since the processing contents themselves are substantially the same as steps S101 to S106 in FIG. 6, the description thereof is omitted.

When the target temperature is determined for each case (steps S204, S205, S208, S211), the target temperature determination process is terminated and the process returns to the flowchart of FIG.
Note that the value of the predetermined value H is also the heating capacity in the fixing unit 40 of the model to be applied, the power consumption per punch process in the punch unit 131 of the post-processing device 130, and the consumption per staple process in the staple unit 132. It is specifically determined by electric power. In this modification, for example, H = 9 is set.

(2) Print job data received from an external terminal includes a header including image information and control information such as a print mode and other image forming conditions, and an image data body. Therefore, it is necessary to develop (data convert) the bitmap data into printable bitmap data.
However, when the amount of image data is large and the double-sided printing mode or the aggregated image mode such as 2in1 is designated as the print mode (image forming condition), the image data for a plurality of pages is collected. If the data has not been converted, it may not be possible to proceed to the printing operation, and it may take time to start printing.

Therefore, in this modification, by instructing the data conversion of the image data to the bitmap data at the start of warm-up, and then executing the target temperature determination process, the waiting time until the start of printout is minimized. There is a feature in that.
FIG. 8 shows an example of a temperature control flowchart in this case in which a new print job is received from an external terminal and warmed up in the sleep mode.

First, in step S301, it is determined whether a new print job has been received from the external terminal. If a new print job has been received (YES in step S301), warm-up is started immediately (step S302), and the warm The target temperature for up is temporarily set to the first temperature (step S303).
At almost the same time, a data conversion instruction is issued to the image processing unit 53 to start conversion of the received image data into bitmap data (step S304).

When an instruction regarding the print mode is acquired from the header of the new print job (YES in step S305), target temperature determination processing for determining a target temperature in the temperature control is executed based on the print mode (step S306). The contents of the subroutine for the target temperature determination process are the same as those in FIGS.
In step S307, the content determined in the target temperature determination process is confirmed. If the determined target temperature is the second temperature (YES in step S307), the warm-up first temperature is temporarily set. If the determined target temperature is not the second temperature (NO in step S307), the target temperature for warm-up is changed in step S303. The temporarily set first temperature is set as the main setting (step S309).

Thereafter, the control waits until the temperature of the first roller 42 reaches the target temperature (NO in step S310). If it reaches (YES in step S310), temperature control is performed to maintain the target temperature (step S311). ).
If the image data conversion is not completed at that time, the process waits until it is completed (NO in step S312). If completed (YES in step S312), the process returns to a main flowchart (not shown). In the main flowchart, each unit is controlled to execute the received print job.

Thus, by starting the conversion of the image data prior to the determination of the target temperature by the acquired print mode, the conversion of the image data can be executed in parallel with the warm-up control, and the conversion of the image data is performed as soon as possible. The processing can be completed, and the user's convenience can be increased by shortening the waiting time until the start of the print job.
(3) Although the temperature control process in the above embodiment has been described with respect to the process of determining the target temperature and controlling the temperature when the warm-up start condition is satisfied and the warm-up is started, the present invention is not limited to this. For example, even when the next print job is received during execution of the print job, the target temperature may be determined by analyzing the mode of the next print job.

FIG. 9 is a flowchart showing the contents of the temperature control process executed by the control unit 50 in this case.
First, it is determined whether a print job is currently being executed (step S401).
If the print job is being executed (YES in step S401), the temperature control is continued to the target temperature set for the print job (step S402).

Then, it is determined whether or not the print mode of the next print job has been acquired (step S403).
If the print mode of the next print job has been acquired (YES in step S403), a target temperature determination process for executing the next print job is executed (step S404). The contents of the target temperature determination process are the same as those described in FIG. 6 and FIG.

Next, it is determined whether or not the target temperature determined by the target temperature determination process in step S404 is the second temperature (step S405). If the target temperature is the second temperature (YES in step S405), it is determined whether or not the currently set target temperature is the second temperature (step S406).
If the current target temperature is not the second temperature (NO in step S406), the target temperature is changed to the second temperature (step S407), and when the second temperature is reached (YES in step S408). ), Temperature control for maintaining the target temperature (second temperature) is performed (step S409).

If it is determined in step S405 that the target temperature in the next print job is the first temperature (NO in step S405), the target temperature in the current print job execution may be the first or second temperature. Therefore, since it is not necessary to change at this time, temperature control is continued with the target temperature set as it is (step S409).
Even when the current target temperature is set to the second temperature in step S406 (YES in step S406), there is no need to change the temperature in the same manner, so the temperature control is performed at the set target temperature. Continue (step S409).

Then, the process returns to the main flowchart (not shown).
As described above, when the next print job is received during execution of the print job and the target temperature of the next print job is determined to be the second temperature, the second target is started from the execution of the current print job. By controlling the temperature based on the temperature, the next print job can be executed immediately after the end of the current print job, so that the user does not have to wait and the convenience is improved.

(4) In the above embodiment, the punching process and the stapling process executed by the post-processing device 130 are described as an example of the load that should reduce the power to be supplied to the fixing unit 40. However, the present invention is not limited to this. For example, when the post-processing apparatus 130 has a bending function, the bending process can be added.
Also, in the ADF 121 in the image reading apparatus 120, when the reading speed is further increased or when double-sided reading is performed, the power consumption increases and the power supplied to the fixing unit 40 is also increased. It is also possible to bring a decline.

In these cases, an appropriate power load index value corresponding to the process and its threshold value are set, and when the power load index value exceeds the threshold value, the second temperature is determined as the target temperature and the temperature Control is executed.
Further, in some cases, when an additional process that causes a decrease in power supplied to the fixing unit 40 and may cause fixing failure is designated, the second load value is set regardless of the magnitude of the power load index value. You may make it change into temperature. This is because energy saving can be achieved at least as compared with the prior art.

  (5) The fixing unit according to the present invention has been described with respect to the induction heating type, but is not limited thereto, and a configuration using a halogen heater or a resistance heating element as a heating source may be used. However, from the viewpoint of enabling continuous printing due to power shortage when performing other additional processing in parallel by increasing the amount of heat storage at the second temperature, the structure having a certain amount of heat capacity is better. The heat storage effect is high, and the effect of the present invention can be exhibited more.

(6) In the above embodiment, the post-processing device 130 is an optional device and is configured to be detachable from the image forming apparatus main body 110. However, the image forming apparatus main body 110 and the post-processing apparatus 130 are It may be an integrated image forming apparatus.
(7) In the above embodiment, the temperature control in the multifunction machine having the tandem color digital printer as the main body of the image forming apparatus has been described. However, the scope of application of the present invention is not limited to this. The present invention can be generally applied to an image forming apparatus such as an apparatus, a printer, and the like, which has a function of executing additional processing that causes a decrease in power to a fixing unit in parallel during an image forming operation.

  Further, the contents of the above-described embodiment and modification examples may be combined as much as possible.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a technique for preventing a fixing failure while realizing energy saving in an image forming apparatus having a function of executing an additional process that causes a decrease in power supply to a fixing unit when executing a print job. It is.

DESCRIPTION OF SYMBOLS 10 Image process part 20 Intermediate transfer part 30 Paper feed part 40 Fixing part 45 Excitation coil 48 Temperature sensor
50 control unit 51 CPU
52 Communication I / F Unit 53 Image Processing Unit 54 Image Memory 55 Laser Diode Drive Unit 56 ROM
57 RAM
60 Power Supply Unit 100 Multifunction Machine 110 Image Forming Apparatus Main Body 120 Image Reading Device 121 Automatic Document Feeding Device 123 Image Reading Control Unit 130 Post-Processing Device 131 Punching Unit 132 Stapling Unit 133

Claims (10)

An image forming apparatus in which a toner image carried on an image carrier is transferred onto a recording sheet and then thermally fixed by a fixing member heated by a heating unit in a fixing device,
Determining means for determining a target temperature that the fixing member should reach when an image forming job is executed;
Temperature control means for controlling the heating means so that the temperature of the fixing member becomes the determined target temperature;
With
The determination unit determines whether or not an additional process that generates a load that causes a reduction in power to be supplied to the heating unit is specified in the image forming job to be executed, and the additional process is not specified In the image forming apparatus, the first temperature is set as the target temperature, and when the additional processing is designated, the second temperature higher than the first temperature is set as the target temperature. The post-processing device connected to the image forming apparatus main body and sharing a power supply unit with the image forming apparatus main body, and the additional processing is post-processing executed by the post-processing device. The image forming apparatus described in 1. An acquisition unit that acquires a power load index value that indicates a degree of load that causes a decrease in power to be supplied to the heating unit by performing the additional process;
And a prohibiting unit that prohibits the determining unit from determining the target temperature to the second temperature when the power load index value is less than a preset load amount for the additional processing. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The additional processing is punch processing for forming punch holes in a recording sheet on which image formation has been performed, and the power load index value is the number of images formed in an image forming job to be executed,
4. The image according to claim 3, wherein the prohibiting unit prohibits the determining unit from determining a target temperature to be the second temperature when the number of formed images is less than a predetermined number. 5. Forming equipment. The additional process is a staple process for stapling the image-formed recording sheet part by part, and the power load index value is the number of recording sheets constituting each part in the image forming job to be executed. The number of copies
The prohibiting means is configured such that the determining means sets the target temperature to the second temperature, except when the number of each part is equal to or less than the first threshold and the number of copies is equal to or greater than the second threshold. The image forming apparatus according to claim 3, wherein the determination is prohibited. The additional processing is a composite post-processing for performing stapling for stapling a portion of the recording sheet after performing punch processing for forming punch holes in the recording sheet on which image formation has been performed, and the power load index The value is the sum of the total number of images formed in the image forming job to be executed and the number of copies to be stapled,
The said prohibiting means prohibits that the said determination means determines a target temperature to a said 2nd temperature when the said electric power load index value is less than predetermined value. Image forming apparatus. Accepting means for accepting an image forming job from an external terminal via a network;
Data conversion means for converting the image data in the accepted image forming job into data in a format capable of image formation, so as to start data conversion by the data conversion means prior to determination of the target temperature by the determination means The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. When the next second image forming job is received during the execution of the preceding first image forming job,
In the temperature control unit, the determination unit determines that the target temperature for the second image forming job is the second temperature, and the target temperature in the first image forming job currently being executed is the first temperature. The image forming apparatus according to claim 1, wherein the temperature is controlled by switching the target temperature to the second target temperature during execution of the first image forming job. A method for controlling the temperature of a fixing device in an image forming apparatus in which a toner image carried on an image carrier is transferred onto a recording sheet and then thermally fixed by a fixing member heated by a heating unit in the fixing device.
A determination step for determining a target temperature to be reached by the fixing member when the image forming job is executed;
A temperature control step for controlling the heating means so that the temperature of the fixing member becomes the determined target temperature;
Including
In the image forming job to be executed, the determining step determines whether or not an additional process for generating a load that causes a reduction in power to be supplied to the heating unit is specified. When the additional process is not specified The temperature control of the fixing device is characterized in that the first temperature is set as the target temperature, and when the additional processing is designated, the second temperature higher than the first temperature is determined as the target temperature. Method. An acquisition step of acquiring a power load index value indicating the degree of load that causes a decrease in power to be supplied to the heating means by performing the additional process;
A step of prohibiting the determination of the target temperature to the second temperature in the determination step when the power load index value is less than a load amount set in advance for the additional processing. The temperature control method for a fixing device according to claim 9, wherein:

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