JP5077328B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a fixing device that thermally fixes a toner image on a sheet, and more particularly to power saving of a standby fixing device.

  In a conventional image forming apparatus such as a copying machine or a facsimile, an electrostatic latent image is formed by exposing a charged photoreceptor, and a toner image visualized by attaching toner to the electrostatic latent image is formed. After the transfer to the paper, the toner image transferred to the paper is heated and fixed by a fixing device. Heat fixing is performed by raising the fixing device to a predetermined temperature with a heater, but it takes a long time to raise the cooled fixing device to a fixable temperature. For this reason, even when copying is not performed in a normal copying machine, a current is supplied to the heater to keep the fixing device close to a usable temperature, thereby shortening the warm-up time after receiving a printing request. It is done. However, if this is done, there arises a problem that the amount of power consumption when the copying process is not performed becomes large. Accordingly, various techniques for reducing power consumption while shortening the warm-up time of the fixing device have been proposed.

  For example, the timing of starting the temperature reduction of the fixing device during standby based on the usage history data such as the time of image formation processing and the number of copies for each time zone, based on the usage history data of the time zone to which the current time belongs In addition, there is an image forming apparatus that controls the inclination of lowering the temperature or the like (see Patent Document 1).

  Also, focusing on the fact that the optimal standby temperature of the fixing device varies depending on the paper type (thickness, etc.), the number of sheets that have passed through the fixing roller for each paper type is collected as usage frequency data, and the temperature of the fixing device during standby is collected. Has been proposed (see, for example, Patent Document 2) that controls the temperature to a temperature suitable for the type of paper that is used most frequently.

  Incidentally, in an image forming apparatus corresponding to a plurality of types of paper sizes such as A4 and A3, a fixing device corresponding to the maximum width among the plurality of types of sheets is provided. However, if the entire fixing device is always heated in accordance with the maximum width of the sheet when heat fixing, the portion that is not passed through is heated when fixing a narrow sheet of paper, and power is wasted. Therefore, there is an image forming apparatus that uses a fixing device that can be heated for each divided region and controls the temperature at the time of heat fixing for each region in accordance with the size of the paper to be passed.

JP-A-8-241209 JP 2008-216705 A

  As described above, there are image forming apparatuses that control the temperature at the time of thermal fixing for each fixing region with respect to the fixing device that can be controlled by heating for each region. However, there is no one that performs temperature control during standby by taking advantage of the characteristics of a fixing device that can control heating by region.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of performing temperature control during standby by taking advantage of characteristics of a fixing device capable of heating control for each region. .

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] In an image forming apparatus having a fixing device for fixing a toner image by heating a recording paper on which an unfixed toner image is formed.
The fixing device includes:
A heating member for heating the recording paper;
Heating means capable of heating the first region and the second region of the heating member to different temperatures;
Have
A control unit that controls a heating unit to preheat the heating member during a standby period in which printing is not performed, and controls the temperature of the second region to be lower than that of the first region. have a control unit provided with a pattern,
Printing can be performed on a first recording paper having a first width and a second recording paper having a second width larger than the first width, and the first area is formed on the first recording paper and the second recording paper. A common paper passing area, and the second area is a paper passing area for only the second recording paper of the first recording paper and the second recording paper,
The control unit controls the temperature of the second region to be more greatly decreased with respect to the temperature of the first region in the control pattern as the frequency of printing on the recording paper of the second width is lower. An image forming apparatus.

  In the above invention, in the preliminary heating of the fixing device during the standby period in which printing is not performed, the second region is controlled to a temperature lower than that of the first region.

  In the above invention, the first area is a sheet passing area common to the first recording sheet and the second recording sheet wider than the first recording sheet, and the second area is a sheet passing area of the second recording sheet. This is an area that is not a recording paper passing area, that is, an area that protrudes from the first area of the second recording paper passing area. The temperature of the second region used for fixing only the wide second recording paper is lower in the preliminary heating during the standby period than the first region commonly used for the first and second recording papers. To be controlled.

In the above invention, the lower the printing frequency of the second recording paper, the lower the temperature of the second area is controlled with respect to the first area. The frequency of printing on the second recording paper is, for example, by counting the number of prints in the most recent predetermined period (for example, several hours, one day, or one week), the frequency of printing by day of the week, or time zone, Use the printing frequency of the time zone.

[ 2 ] When the frequency of printing on the recording paper of the second width is less than a predetermined value, the control unit controls the heating unit with the control pattern during the standby period, and the frequency is equal to or higher than the predetermined value. In this case, the image forming apparatus according to [1 ], wherein the heating unit is controlled so that the first region and the second region have the same temperature during the standby period.

  In the above invention, when the printing frequency of the second recording paper is less than the threshold value, preheating is performed with the control pattern that lowers the temperature of the second area compared to the first area, and the printing frequency of the second recording paper is When it is equal to or higher than the threshold value, the preheating is controlled so that the first region and the second region have the same temperature.

[ 4 ] Further, when the standby period continues for the first period , the control unit controls the preheating for the second region to be off or at a lower temperature than before, and the standby period is longer than the first period. The image forming apparatus according to any one of [1] to [3], wherein when the period of 2 continues, the preheating for the first region is turned off or off control is performed to control the temperature to a lower temperature than before. .

  In the above invention, in the preliminary heating of the fixing device during the standby period in which printing is not performed, the timing for lowering the temperature or turning off the heating is controlled to be earlier in the second region than in the first region.

That is, the width a second area used for fixing of only the second recording paper size, a reduction of the temperature in the first, early during the waiting period as compared to the first region to be used in common to the second recording paper Or heating is turned off.

[5] wherein, according to the based on the frequency of the printing on the recording paper of the second width, and sets the length of the first period in the control pattern [4] Image forming apparatus.

  In the above invention, the length of the period until the temperature of the second region through which only the second recording sheet passes is lowered according to the printing frequency of the second recording sheet. For example, as the frequency of printing on the second recording paper is lower, control is performed to shorten the length of the period from when the print standby state is reached until the temperature of the second region is lowered. The frequency of printing on the second recording paper is, for example, by counting the number of prints in the most recent predetermined period (for example, several hours, one day, or one week), the frequency of printing by day of the week, or time zone, Use the printing frequency of the time zone.

[ 6 ] The control unit performs the off control only when the frequency of printing on the recording paper of the second width is less than a predetermined value, and when the frequency is equal to or higher than the predetermined value, the waiting period is predetermined. The image forming apparatus according to [ 4] or [5] , wherein preheating for the first region and the second region is controlled to be OFF or lower than before when the period continues.

  In the above invention, when the printing frequency of the second recording paper is less than the threshold value, preheating is performed with the control pattern in which the temperature of the second area is lowered or turned off earlier than the first area, so that the second recording is performed. When the paper printing frequency is equal to or higher than the threshold, the length of the period until the temperature is lowered or the heating is turned off is the same in the first area and the second area.

[ 7 ] The heating means includes a heater that heats the first region and a heater that heats the second region. [ 7 ] According to any one of [1] to [ 6 ], Image forming apparatus.

  In the above invention, a dedicated heater is provided in the first region and a dedicated heater is provided in the second region.

[ 8 ] The heating means includes a heater that heats the first region and the second region, a heater that heats only the first region of the first region and the second region, and The image forming apparatus according to any one of [1] to [ 7 ], wherein the image forming apparatus includes:

  In the said invention, the heater which heats both a 1st area | region and a 2nd area | region, and the heater which heats only a 2nd area | region are provided.

  According to the image forming apparatus of the present invention, the temperature control for the standby fixing apparatus is performed for each of the divided areas, so that it is possible to more effectively reduce the warm-up time and power consumption of the fixing apparatus. .

1 is an explanatory diagram illustrating an outline of a mechanical configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing an electrical schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an explanatory diagram schematically showing the configuration of a heat fixing roller and a heater of the fixing device according to the first and second embodiments of the present invention and a connection with a heater control unit. It is a characteristic view which shows an example of the graph which shows the relationship between A3 frequency and the control temperature of a main heater and a sub heater. It is a flowchart which shows the heating control operation | movement which the heater control part which concerns on 1st Embodiment performs. 6 is a control condition table showing control conditions related to the preheating control of FIG. 5. FIG. 7 is an explanatory diagram showing changes in heater temperature when the A3 frequency is less than a threshold in the control based on FIGS. 5 and 6. It is a flowchart which shows the heating control operation | movement which the heater control part which concerns on 2nd Embodiment performs. It is a control condition table | surface which shows the control conditions regarding the preheating control of FIG. It is explanatory drawing which shows the change of heater temperature in case A3 frequency is less than a threshold value in control based on FIG. 8, FIG. FIG. 3 is an explanatory diagram illustrating an example of a fixing device in which the arrangement and connection of a main heater and a sub heater in a heat fixing roller are different. FIG. 10 is an explanatory diagram illustrating another example of a fixing device in which the arrangement and connection of a main heater and a sub heater in a heat fixing roller are different. FIG. 10 is an explanatory diagram showing still another example of a fixing device in which the arrangement and connection of the main heater and the sub heater in the heat fixing roller are different. FIG. 10 is an explanatory diagram illustrating a fixing device according to a third embodiment. It is a flowchart which shows the heating control operation | movement which the heater control part which concerns on 3rd Embodiment performs. It is a control condition table | surface which shows the control conditions regarding the preheating control of FIG. FIG. 17 is an explanatory diagram showing changes in heater temperature when the A3 frequency is equal to or higher than a threshold in the control based on FIGS. 15 and 16.

  Hereinafter, various embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 shows a mechanical schematic configuration of an image forming apparatus 10 according to a first embodiment of the present invention. The image forming apparatus 10 is configured as a so-called printer apparatus having a function of printing an image corresponding to print data received from an external terminal on a recording sheet and outputting it.

  The image forming apparatus 10 includes a paper feed tray 11 that stores recording paper to be used for printing, a transport unit 12 that feeds the recording paper from the paper feed tray 11 and transports it along a paper path W, a photoconductor 13, The apparatus includes a charging device 14, a laser unit 15, a developing device 16, a transfer device 17, a separating device 18, a cleaning device 19, a fixing device 30, and the like.

  A plurality of paper feed trays 11 are provided. Here, a first paper feed tray 11a and a second paper feed tray 11b are provided, and for example, recording papers having different sizes are stored therein. The photosensitive member 13 has a cylindrical shape and is rotated in a certain direction (the direction of arrow A in the drawing) by a driving unit (not shown). During rotation, the photosensitive member 13 is uniformly charged by corona discharge by the charging device 14, and then subjected to scanning of laser light that is turned on / off according to image data from the laser unit 15, and electrostatic latent image on the surface thereof. An image is formed. The developing device 16 visualizes the electrostatic latent image formed on the surface of the photoreceptor 13 as a toner image.

  The transport unit 12 feeds the recording paper from one of the paper feed trays 11 and feeds the recording paper between the photoconductor 13 and the transfer device 17 at an appropriate timing. The transfer device 17 electrostatically transfers the toner image formed on the surface of the photoreceptor 13 onto the recording paper conveyed by the conveyance unit 12. The separation device 18 performs charge removal to separate the recording paper from the photoreceptor 13. The cleaning device 19 cleans the toner remaining on the photosensitive member 13 after the transfer and separation by rubbing with a blade or the like. The recording sheet on which the toner image has been transferred and separated from the photosensitive member 13 is further conveyed by the conveying unit 12 and is pressed and heated when passing through the fixing device 30 to fix (fix) the toner image on the recording sheet. The paper is discharged.

  The fixing device 30 has a cylindrical shape, and a heat fixing roller 31 as a heating member that is supported and rotated at both ends of a central axis thereof, and a heating unit that heats the heat fixing roller 31 inside the heat fixing roller 31. And a pressing roller 34 that is disposed opposite to the heat fixing roller 31 and is urged and pressed toward the heat fixing roller 31. When the recording paper passes between the heat fixing roller 31 and the pressure roller 34, the recording paper is pressed from the front and back by the heat fixing roller 31 and the pressure roller 34 and is heated by the heat fixing roller 31.

  FIG. 2 shows an electrical schematic configuration of the image forming apparatus 10. The image forming apparatus 10 connects a communication unit 22, a storage unit 23, a nonvolatile memory 24, an operation display unit 25, and a printer unit 26 to a control unit 21 that performs overall control of the operation of the image forming apparatus 10. Composed.

  The control unit 21 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like that are not shown in the figure. Various programs are stored in the ROM, and the functions of the image forming apparatus 10 are realized by the CPU executing processes according to these programs. The RAM is used as a work memory for temporarily storing various data when the CPU executes a program.

  The communication unit 22 has a function of communicating with various devices on the network by connecting to a network such as a LAN (Local Area Network) or the Internet. For example, it is used when print data to be printed is received from an external terminal.

  The storage unit 23 is a large-capacity storage device used for storing print data and image data obtained by rasterizing the print data. Here, the storage unit 23 includes a hard disk device and its controller.

  The operation display unit 25 has a function of displaying various operation screens, setting screens, selection screens, guidance screens, and the like, and a function of receiving various operations from the user. Here, it is composed of a liquid crystal display (LCD ...) that assumes the display function, a touch panel that is formed on the surface of the liquid crystal display and detects the pressed coordinate position, a numeric keypad, a start button, and various operation switches. The

  The printer unit 26 has the mechanical configuration shown in FIG. 1 and executes a printing operation. The printer unit 26 includes a heater control unit 35 that controls the heating of the heater 32 of the fixing device 30. Operations of mechanisms such as the conveyance unit 12 and the photosensitive member 13 included in the printer unit 26 are controlled by the control unit 21.

  The nonvolatile memory 24 stores user information and various setting information that should be saved even when the power is turned off. Further, frequency data indicating the frequency of printing is stored for each size of the recording paper. Here, the size of the recording paper is distinguished based on the width of the recording paper passing through the fixing device 30, and the number of printed sheets for each size is stored as frequency data.

  FIG. 3 schematically shows the configuration of the heat fixing roller 31 and the heater 32 of the fixing device 30 and the electrical connection with the heater control unit 35. The heat fixing roller 31 is divided into a first region 36 and a second region 37 that can be heated to different temperatures by the heater 32. The first area 36 is a sheet passing area (common area) through which the recording paper having the first width and the second recording paper having the second width larger than the first width pass. Reference numeral 37 denotes a paper passing area (a protruding area) through which only the second recording paper of the first recording paper and the second recording paper passes.

  In the following example, the first width is the length of the short side of the A4 size recording paper, and the second width is the length of the short side of the A3 size recording paper. When A4 size recording paper (first recording paper) is conveyed and printed in the long side direction (hereinafter referred to as A4 portrait (A4 sef) printing), the recording paper passes through the second area 37. Without passing through the first region 36, the heat fixing is performed. That is, the first area 36 is a paper passing area when A4 vertical recording paper is thermally fixed. On the other hand, when A3 size recording paper (second recording paper) is conveyed and printed in the long side direction (hereinafter referred to as A3 printing), the recording paper includes the first area 36 and the second area. 37 is passed through both and fixed by heat. That is, the area including the first area 36 and the second area 37 adjacent thereto is a sheet passing area when the A3 recording sheet is thermally fixed.

  The size of the first area 36 does not need to coincide with the short side of A4 (the size of the first recording paper), and may be made somewhat larger or smaller than the short side of A4. Similarly, the width of the combined area of the first area 36 and the second area 37 may not coincide with the short side of A3 (the size of the second recording paper), and may be increased to some extent.

  Inside the heat fixing roller 31, a main heater 32 a that is disposed at a location corresponding to the first region 36 and heats the first region 36, and a second heater 37 a that is disposed at a location corresponding to the second region 37. A sub-heater 32b for heating 37 is provided. The sub-heater 32b includes a right sub-heater 32bR disposed on one side (right side in the figure) of the main heater 32a and a left sub-heater 32bL disposed on the other side (left side in the figure) of the main heater 32a. The main heater 32a, the right sub-heater 32bR, and the left sub-heater 32bL are individually connected to a heater drive circuit included in the heater control unit 35.

  Inside the heat fixing roller 31, a temperature sensor 38 for individually detecting the temperature of the first region 36 and the temperature of the second region 37 corresponds to each of the main heater 32a and the sub heaters 32bR and 32bL. Is provided. Each temperature sensor 38 is connected to the heater control unit 35.

  Frequency data read from the nonvolatile memory 24 is input to the heater control unit 35 at a predetermined timing. Further, the control unit 21 receives a print signal 41 indicating whether printing by the printer unit 26 is being executed and a size signal 42 indicating the size of the recording paper being printed.

  The heater control unit 35 recognizes based on the print signal 41 whether printing is in progress or a standby period in which printing is not being performed. During printing, the recording paper size is recognized based on the size signal 42, and the heating of the main heater 32a and the sub heater 32b is controlled in accordance with the size of the recording paper. When the heater control unit 35 enters a standby period in which printing is not performed, the heater control unit 35 performs a preheating operation for preheating the heat fixing roller 31 in preparation for the next printing.

  The preheating operation is performed with a first control pattern for controlling the first region 36 and the second region 37 at different temperatures, or a second control pattern for controlling the first region 36 and the second region 37 at the same temperature. Is called. Which control pattern is to be used is determined based on frequency data indicating the printing frequency (A3 frequency in this example) of recording paper in which both the first area 36 and the second area 37 pass through the paper area. ing. In the first embodiment, when the A3 frequency is low, the preheating operation is performed with the first control pattern for controlling the heating of the main heater 32a and the sub heater 32b so that the temperature of the second region 37 is lower than that of the first region 36. If the A3 frequency is high, the preheating operation is controlled by the second control pattern for controlling the heating of the main heater 32a and the sub heater 32b so that the first region 36 and the second region 37 have the same temperature. It has become.

  In the heater configuration shown in FIG. 3, that is, the main heater 32a only heats the first region 36 and the sub-heater 32b only heats the second region 37, the temperature of the first region 36 is the main heater. The temperature of the second region 37 corresponds to the temperature of the sub heater 32b. Therefore, in the following description, the temperature control related to the first region 36 will be described as the temperature control of the main heater 32a, and the temperature control related to the second region 37 will be described as the temperature control of the sub heater 32b.

  FIG. 4 shows an example of the relationship between the A3 frequency and the control temperatures of the main heater 32a and the sub heater 32b. In FIG. 4, the temperature Tm of the main heater 32a is controlled to a constant temperature in the preheating regardless of the A3 frequency. On the other hand, the temperature Ts of the sub-heater 32b is controlled to a temperature equivalent to the main heater 32a when the frequency of A3 is equal to or higher than the threshold F, and is controlled to a temperature lower than the main heater 32a when the frequency is less than the threshold F. In the example of FIG. 4, the temperature of the second region 37 is decreased more greatly with respect to the first region 36 as the frequency of A3 is lower.

  When the frequency of A3 is high, the heater control unit 35 has a high probability that A3 will be printed after the end of the standby period. Therefore, in the preheating operation, the sheet passing area (first area 36 + second area) corresponding to the A3 size is used. The preheating is controlled so that 37) is maintained at a temperature close to the printable temperature. On the other hand, when the frequency of A3 is low, the probability that A3 will be printed after the end of the standby period is low, so only the paper passing area (first area 36) corresponding to the A4 vertical size is held at a temperature near the printable temperature. Control the preheating so that it does. Thereby, the shortening of the warm-up time to the printable temperature and the power saving in the preheating are compatible with a balance according to the use frequency of A3.

  Next, heating control of the heater 32 by the heater control unit 35 will be described in more detail. FIG. 5 shows a flow of a heating control operation performed by the heater control unit 35 according to the first embodiment, and FIG. 6 shows a control condition table 50 showing control conditions related to the preheating control of FIG. In this example, when the A3 frequency is greater than or equal to the threshold value, the preheating operation is performed with the second control pattern, and when the A3 frequency is less than the threshold value, the preheating operation is controlled with the first control pattern. The threshold value is not limited to that shown in FIG. 4, and may be set to a value lower than threshold value F in FIG. 4, for example, or an appropriate value may be set as appropriate. FIG. 7 shows changes in the heater temperature during the standby period after the A4 portrait printing in the control based on FIGS. 5 and 6 when the A3 frequency is less than the threshold value.

  The heater control unit 35 determines whether printing (printing out) is being performed based on the print signal 41 input from the control unit 21 (FIG. 5: step S101). If printing is in progress (step S101; Yes), based on the size signal 42 input from the control unit 21, it is determined whether the printing is performed in A4 portrait (A4 sef) (step S102). In the case of A4 portrait (step S102; Yes), the main heater 32a is controlled to be heated to a temperature H5 which is a printable temperature, and the sub heater 32b is controlled to a temperature H4 slightly lower than the temperature H5 (step S103), and the process proceeds to step S105. On the other hand, when it is not A4 vertical (in the case of A3) (step S102; No), the main heater 32a and the sub heater 32b are controlled to be heated to a temperature H5 (step S104) and the process proceeds to step S105.

  In step S <b> 105, the frequency data stored in the nonvolatile memory 24 is updated through the control unit 21. That is, if printing is performed in A4 portrait, the frequency data for counting the number of A4 portrait printed is incremented by 1, and if printing is performed in A3 (if not A4 portrait), the number of A3 prints is counted. 1 is added to the frequency data.

  After the frequency data is updated, while the printing continues (Step S106; No), the heating control at the temperature set in Step S103 or Step S104 is continued and the printing is finished (Step S106; Yes). Returning to step S101, the processing is continued.

  When the printing is not in progress (standby period) (step S101; No), the heater control unit 35 performs a preheating operation. Specifically, when the standby period starts, the frequency data (A3 frequency data) stored in the nonvolatile memory 24 is read and acquired through the control unit 21 (step S107), and the A3 frequency is determined in advance from the frequency data. It is determined whether or not the threshold value is exceeded (step S108).

  When the A3 frequency is equal to or higher than the threshold value, the preheating is controlled by the second control pattern. That is, (step S108; Yes), both the main heater 32a and the sub heater 32b are controlled to be heated to the temperature H5 (step S109). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T2 (step S111), and before T2 elapses (step S111; No), the next printing is started ( If the print signal 41 indicating that printing is in progress is input from the control unit 21 (step S110; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the standby period has elapsed for T2 hours without starting the next printing (step S111; Yes), the heating control is performed by changing the target temperature to the temperature H4 for both the main heater 32a and the sub heater 32b (step S112). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T3 (T3> T2) (step S114), and before T3 elapses (step S114; No), the next printing is performed. Is started (step S113; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the waiting period has elapsed for T3 hours without starting the next printing (step S114; Yes), both the main heater 32a and the sub heater 32b are turned off (temperature H1 corresponds to heater OFF) (step S121). As a result, the standby preheating operation is completed. Thereafter, the next printing start is waited in a state without preheating, and when the next printing is started (a print signal 41 indicating printing is input from the control unit 21) (step S122; Yes), step S102 is performed. If the next printing is not started (step S122; No), the process is terminated.

  When the A3 frequency is less than the threshold value (step S108; No), the preheating is controlled with the first control pattern. That is, the main heater 32a is controlled to be heated to a temperature H5, and the sub heater 32b is controlled to be a temperature H3 that is lower than the temperature H4 (step S115). In a state where the heating control is maintained, the process waits for the elapsed time after entering the standby period to pass T2 (step S117), and the next printing is started before T2 has passed (step S117; No). (Step S116; Yes), the process proceeds to Step S102 and the above-described processing is performed.

  When the standby period has elapsed for T2 hours without starting the next printing (step S117; Yes), the main heater 32a is heated to a temperature H4, and the sub heater 32b is heated to a temperature H2 lower than the temperature H3. (Step S118). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T3 (T3> T2) (step S120), and before T3 has passed (step S120; No), the next printing is performed. Is started (step S119; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the waiting period has elapsed for T3 hours without starting the next printing (step S120; Yes), both the main heater 32a and the sub heater 32b are turned off (temperature H1) (step S121). Thereafter, the next printing start is waited without preheating, and when the next printing is started (step S122; Yes), the process proceeds to step S102, and if the next printing is not started (step S122; No). This process ends.

  With the above control, when the A3 frequency is less than the threshold, the temperature change Tm of the main heater 32a and the temperature change Ts of the sub heater 32b during the standby period are as shown in FIG. That is, when the A3 frequency is less than the threshold, the temperature Ts of the sub heater 32b is controlled to be lower than the temperature Tm of the main heater 32a. Note that the temperature change of the main heater 32a and the sub heater 32b when the A3 frequency is equal to or higher than the threshold is the same as the temperature Tm of the main heater 32a in FIG.

<Second Embodiment>
In the first embodiment, when the A3 frequency is low, the temperature of the second region in which only A3 passes through the first region 36 in which A4 length and A3 pass in common in the preliminary heating during the standby period in which printing is not executed. Was controlled to be a low temperature. In contrast, in the second embodiment, in the standby period when the frequency of A3 is low, the heating temperature is lowered or the heating is turned off earlier in the second region 37 than in the first region 36. So that it is controlled. The image forming apparatus 10 according to the second embodiment is the same as the first embodiment shown in FIGS. 1, 2, and 3 except that the above control is different, and the description thereof is omitted. To do.

  FIG. 8 shows the flow of the heating control operation performed by the heater control unit 35 according to the second embodiment, and FIG. 9 is a control condition table 52 showing the control conditions related to the preheating control of FIG. In this example, as in the first embodiment, the control pattern of the preheating operation is switched between the case where the A3 frequency is greater than or equal to the threshold value and the case where the A3 frequency is less than the threshold value. FIG. 10 shows changes in the heater temperature during the standby period after A4 vertical printing when the A3 frequency is less than the threshold in the control based on FIGS. 8 and 9.

  In FIG. 8, the operation when printing (printout) and the operation during the standby period when the A3 frequency is greater than or equal to the threshold value are the same as those in FIG. 5, and these are the same step numbers as in FIG. S114) will be added and description thereof will be omitted. Step S224 is the same operation as S121 in FIG. 5, and step S225 is the same operation as S122 in FIG. Hereinafter, the operation when the A3 frequency is less than the threshold will be described.

  When the A3 frequency is less than the threshold value (step S108; No), the main heater 32a is controlled to be heated to the temperature H5, and the sub heater 32b is controlled to be heated to the temperature H4 (step S215). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T1 (T1 <T2) (step S217), and before T1 elapses (step S217; No), the next printing Is started (step S216; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the waiting period has passed T1 without starting the next printing (step S217; Yes), the main heater 32a continues the temperature H5, and the sub-heater 32b is controlled to be at a temperature H2 lower than the temperature H4. (Step S218). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T2 (T2> T1) (step S220), and before T2 elapses (step S220; No), the next printing is performed. Is started (step S219; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the standby period has passed T2 without starting the next printing (step S220; Yes), the main heater 32a is changed to the temperature H4, and the sub-heater 32b is controlled to be kept at the temperature H2 (step S220). S221). While maintaining this heating control, it waits for the elapsed time from entering the standby period to pass T3 (T3> T2) (step S223), and before T3 has passed (step S223; No), the next printing Is started (step S222; Yes), the process proceeds to step S102 and the above-described processing is performed.

  When the waiting period has elapsed for T3 hours without starting the next printing (step S223; Yes), both the main heater 32a and the sub heater 32b are turned off (temperature H1) (step S224). Thereafter, the next printing start is waited without preheating, and when the next printing is started (step S225; Yes), the process proceeds to step S102, and if the next printing is not started (step S225; No). This process ends.

  With the above control, when the A3 frequency is less than the threshold, the change in the temperature Tm of the main heater 32a and the change in the temperature Ts of the sub heater 32b during the standby period are as shown in FIG. That is, when the A3 frequency is less than the threshold, the temperature Ts of the sub-heater 32b is decreased from H4 to H2 when T1 elapses after the start of the standby period, and thereafter when T2 longer than T1 elapses after the start of the standby period. Thus, the temperature of the main heater 32a is lowered from H5 to H4. That is, the control for lowering the temperature is performed earlier for the sub heater 32 b for heating the second region 37 than for the main heater 32 a for heating the first region 36. Note that the temperature change of the main heater 32a and the sub heater 32b when the A3 frequency is equal to or higher than the threshold is the same as the change of the temperature Tm of the main heater 32a in FIG.

  In the second embodiment, when the frequency of A3 is high, there is a high probability that A3 will be printed after the end of the waiting period. Therefore, during the waiting period, the sheet passing area corresponding to the A3 size (the first area 36 + the first area). The preheating is controlled so as to keep the second region 37) at a temperature close to the printable temperature. On the other hand, when the frequency of A3 is low, the probability that A3 will be printed after the end of the standby period is low, so that only the paper passing area (first area 36) corresponding to the A4 vertical size is set to a temperature near the printable temperature. The second region 37 that is held and through which only A3 passes is controlled to lower the temperature earlier than the first region 36. Thereby, the shortening of the warm-up time to the printable temperature and the power saving in the preheating are compatible with a balance according to the use frequency of A3.

  11 to 13 show various arrangement examples and connection examples of the main heater 32 a and the sub heater 32 b in the heat fixing roller 31 of the fixing device 30. The temperature sensor 38 is not shown. In FIG. 11, the first region 36 is on one end side of the first region 36, and the second region 37 is disposed adjacent to the other end side of the first region 36.

  In FIG. 12, the arrangement of the first region 36 and the second region 37 is the same as in FIG. 3, but the right sub-heater 32bR for heating the right region of the first region 36 in the second region 37 and the left region. The left sub-heater 32bL for heating the heater is connected in series, and these are driven by one heater drive circuit.

  FIG. 13 shows a configuration in which the main heater 32a and the sub heater 32b are arranged outside the heat fixing roller 31, and the heat fixing roller 31 is heated from the outside.

<Third Embodiment>
In the third embodiment, the arrangement of the main heater 32a and the sub heater 32b in the heat fixing roller 31 of the fixing device 30 is as shown in FIG. 14, and accordingly, the heating control performed by the heater control unit 35 is performed. The flow of operation is different from that of the first and second embodiments. The difference in configuration from the image forming apparatus 10 of the first embodiment is a fixing device 30 shown in FIG. 14, and the configurations shown in FIGS. 1 and 2 are the same as those of the first embodiment. Description of is omitted.

  As shown in FIG. 14, in the fixing device 30 </ b> C according to the third embodiment, the main heater 32 a heats the first region 36 in the central portion of the heat fixing roller 31 and through which A4 length and A3 pass in common. To do. The sub-heater 32b corresponds to the entire sheet passing area A3 and heats almost the entire length of the heat fixing roller 31. A region where the main heater 32 a and the sub heater 32 b overlap is the first region 36, and a region where only the sub heater 32 b exists is the second region 37. The sub-heater 32b is configured to heat both the first region 36 and the second region 37. One temperature sensor 38 is provided in the first region 36 and one temperature sensor 38 is provided in the second region 37 (only in the second region 37 on the right side of the first region 36 in the example of FIG. 14).

  FIG. 15 shows the flow of the heating control operation performed by the heater control unit 35 according to the third embodiment, and FIG. 16 is a control condition table 54 showing the control conditions related to the preheating control of FIG. In the third embodiment, at the time of A3 printing, only the sub-heater 32b is heated and thermally fixed. Further, during the standby period, the operation when the A3 frequency is less than the threshold is the same as that in FIG. 5 of the first embodiment. FIG. 17 shows changes in the heater temperature during the standby period after the A4 portrait printing in the control based on FIGS. 15 and 16 when the A3 frequency is equal to or higher than the threshold value. In the case where the A3 frequency is less than the threshold, the change in the heater temperature during the standby period after the A4 portrait printing is the same as that shown in FIG.

  The heater control unit 35 according to the third embodiment determines whether printing (printing out) is being performed based on the print signal 41 input from the control unit 21 (FIG. 15: step S301). If printing is in progress (step S301; Yes), it is determined whether the printing is performed in A4 portrait (A4 sef) (step S302). In the case of A4 portrait (step S302; Yes), the main heater 32a is heated to a temperature H5 that is a printable temperature, and the sub heater 32b is controlled to a temperature H4 that is slightly lower than the temperature H5 (step S303). On the other hand, when it is not A4 vertical (in the case of A3) (step S302; No), the main heater 32a is turned off (temperature H1), and the sub-heater 32b is controlled to be heated to a temperature H5 (step S304).

  After the heating control in step S303 or S304 is started, the frequency data stored in the nonvolatile memory 24 is updated so that the printing number of A4 portrait is incremented by 1 when printing is performed in A4 portrait, and printing is performed in A3. If it is performed at step A3 (if it is not A4 portrait), the number of printed sheets of A3 is updated by 1 (step S305). Thereafter, while the printing is continued (step S306; No), the heating control started in step S303 or step S304 is continued, and when printing is completed (step S306; Yes), the process returns to step S301.

  When the printing is not in progress (standby period) (step S301; No), the heater control unit 35 performs the preheating operation with the first or second control pattern. Specifically, when the standby period starts, the frequency data stored in the nonvolatile memory 24 is read and acquired through the control unit 21 (step S307), and it is determined from the frequency data whether the A3 frequency is equal to or higher than a threshold value (step S307). Step S308).

  When the A3 frequency is equal to or higher than the threshold (step S308; Yes), the preheating control is performed with the second control pattern. That is, the main heater 32a is turned off (temperature H1), and the sub-heater 32b is controlled to be heated to the temperature H5 (step S309). In a state where the heating control is maintained, waiting for the elapsed time after entering the standby period to pass T2 (step S311), and before the next printing is started before T2 has passed (step S311; No) (Step S310; Yes), the process proceeds to Step S302 to perform the above-described processing.

  When the waiting period T2 has elapsed without starting the next printing (step S311; Yes), the main heater 32a is kept off and the target temperature of the sub heater 32b is changed to the temperature H4 to perform the heating control. This is performed (step S312). While maintaining this heating control, the system waits for the elapsed time after entering the standby period to pass T3 (T3> T2) (step S314), and before T3 elapses (step S314; No), the next printing Is started (step S313; Yes), the process proceeds to step S302 and the above-described processing is performed.

  When the waiting period T3 has elapsed without starting the next printing (step S314; Yes), both the main heater 32a and the sub heater 32b are turned off (step S321). As a result, the standby preheating is completed. Thereafter, the next printing start is waited without preheating, and when the next printing is started (step S322; Yes), the process proceeds to step S302, and if the next printing is not started (step S322; No). This process ends.

  The operation when the A3 frequency is less than the threshold (step S308; No) is the same as the operation in the first embodiment. That is, the processes from step S315 to S322 correspond to steps S115 to S122 in FIG.

  With the above control, when the A3 frequency is less than the threshold, the change in the temperature Tm of the main heater 32a and the change in the temperature Ts of the sub heater 32b during the standby period are as shown in FIG. That is, when the A3 frequency is less than the threshold, the temperature Ts of the sub heater 32b is controlled to be lower than the temperature Tm of the main heater 32a.

  When the A3 frequency is equal to or higher than the threshold, the change in the temperature Tm of the main heater 32a and the change in the temperature Ts of the sub heater 32b during the standby period are as shown in FIG. The temperature Ts of the sub-heater 32b is maintained at the temperature H5 until T2, is lowered to the temperature H4 when T2 is passed, and is turned OFF when T3 has elapsed. On the other hand, the temperature Tm of the main heater 32a is always maintained at the temperature H1 during the standby period, that is, the main heater 32a is maintained in the OFF state.

  In the standby period, when the A3 frequency is equal to or higher than the threshold, the first region 36 and the second region 37 are controlled to the same temperature during the standby period. When the A3 frequency is lower than the threshold, the second region 37 is controlled. Is controlled to a temperature lower than that of the first region 36. Thereby, the shortening of the warm-up time to the printable temperature and the power saving in the preheating are compatible with a balance according to the use frequency of A3.

  The timing of temperature drop may be controlled as shown in the second embodiment using the fixing device 30C shown in FIG. That is, in the case where the frequency of A3 is low, in the standby period, when controlling the heating temperature to be lowered or the heating OFF timing to be earlier than the first region 36 relative to the second region 37, A part of the flowchart shown in FIG. Specifically, steps S315 to S322 may be replaced with steps S215 to S225 in FIG.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  In the embodiment, the A4 portrait is described as the recording sheet having the first area 36 as the sheet area, and the recording sheet having the area including the first area 36 and the second area 37 as the sheet area is described as A3. However, it is not limited to these. That is, in the embodiment, the control pattern is switched based on the frequency of A3, but only the first area 36 is included in the paper area and the recording area that does not pass through the second area 37, for example, A4 portrait, B5 portrait, etc. Control the preheating based on the printing frequency of the second recording paper, which is the recording paper, and the recording paper including the first area 36 and the second area 37 in the paper area, for example, A3, B4, etc. It may be configured to switch patterns.

  The first area 36 is an area wider than the width of the narrow recording paper (A4 length in the embodiment) and narrower than the width of the wide recording paper (A3 in the embodiment). The area including the second area 37 may be set wider than the wide recording sheet.

  In the embodiment, the control pattern in the preheating is switched based on the frequency data. However, the control pattern may be switched according to a separate reference or user setting. For example, whether the heating during the standby period is performed with the second control pattern when the A3 frequency in the embodiment is greater than or equal to the threshold value, or with the first control pattern when the A3 frequency in the embodiment is less than the threshold value, It may be configured to be able to set in advance, and may be configured to control preheating during the standby period according to the setting. For example, the administrator or the like sets the first control pattern when the image forming apparatus 10 is installed in an office or the like where A3 is frequently used, and sets the second control pattern when the frequency of A3 or the like is low. Then, preheating control is performed according to the usage situation at the installation location.

  The frequency that serves as a reference for control pattern switching, such as A3 frequency data, may be the printing frequency in the latest predetermined period, or may be the printing frequency in another counting period. For example, several hours, a day, or a week may be set as the predetermined period recently. Further, the printing frequency may be totaled by day of the week or time zone, and the control pattern in the preheating operation may be selected by referring to the printing frequency corresponding to the day of the week or time zone when entering the preheating operation. Good.

  The preheating control in the first embodiment and the preheating control in the second embodiment may be combined. That is, when the A3 frequency is less than a threshold value, the temperature of the second region 37 is controlled to be lower than that of the first region 36, and the timing of lowering the temperature of the second region 37 is earlier than that of the first region 36. May be.

  In the embodiment, the fixing device 30 is a type in which the recording paper is nipped and pressed between the heat fixing roller 31 and the pressure roller 34. Different methods may be used. For example, one or both of the circulating belt and the roller may be heated, and the recording paper may be nipped between them and pressed. Any structure may be used as long as one heating member is heated by a plurality of heaters.

  As long as the first region 36 and the second region 37 can be controlled in temperature separately, the heater arrangement / configuration and the connection method to the drive circuit are not limited to those exemplified in the embodiment.

  In the embodiment, the printer apparatus has been described as an example. However, the printer apparatus may be configured as a copying machine having a copying function, or a multifunction machine having a copying function, a printer function, a facsimile function, or the like. Other types of image forming apparatuses may be used as long as the toner image is thermally fixed on the recording paper.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 11 ... Paper feed tray 11a ... 1st paper feed tray 11b ... 2nd paper feed tray 12 ... Conveyance part 13 ... Photoconductor 14 ... Charging device 15 ... Laser unit 16 ... Developing device 17 ... Transfer device 18 ... Separating device 19 ... Cleaning device 21 ... Control unit 22 ... Communication unit 23 ... Storage unit 24 ... Non-volatile memory 25 ... Operation display unit 26 ... Printer unit 30, 30C ... Fixing device 31 ... Thermal fixing roller 32 ... Heater 32a ... Main heater 32b ... Sub heater 32bL ... Left sub heater 32bR ... Right sub heater 34 ... Pressing roller 35 ... Heater controller 36 ... First area 37 ... Second area 38 ... Temperature sensor 41 ... Print signal 42 ... Size signal 50, 52, 54 ... Control condition table W: Paper path A: Direction of rotation Tm: Temperature of main heater Ts: Temperature of sub heater F: Threshold value

Claims (8)

In an image forming apparatus having a fixing device for fixing a toner image by heating a recording paper on which an unfixed toner image is formed,
The fixing device includes:
A heating member for heating the recording paper;
Heating means capable of heating the first region and the second region of the heating member to different temperatures;
Have
A control unit that controls a heating unit to preheat the heating member during a standby period in which printing is not performed, and controls the temperature of the second region to be lower than that of the first region. have a control unit provided with a pattern,
Printing can be performed on a first recording paper having a first width and a second recording paper having a second width larger than the first width, and the first area is formed on the first recording paper and the second recording paper. A common paper passing area, and the second area is a paper passing area for only the second recording paper of the first recording paper and the second recording paper,
The control unit controls the temperature of the second region to be more greatly decreased with respect to the temperature of the first region in the control pattern as the frequency of printing on the recording paper of the second width is lower. An image forming apparatus. The control unit controls the heating unit with the control pattern during the standby period when the frequency of printing on the recording paper of the second width is less than a predetermined value, and when the frequency is equal to or higher than the predetermined value. The image forming apparatus according to claim 1, wherein the heating unit is controlled so that the first region and the second region have the same temperature during the standby period.   The temperature of the first area during the waiting period is set to be equal to or lower than the temperature of the first area when printing is performed.
  The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The controller further controls the preheating for the second region to be off or lower than before the standby period when the standby period continues for the first period, and the standby period is a second period longer than the first period. 4. The image forming apparatus according to claim 1, wherein when the operation is continued, the preheating for the first region is turned off or off control is performed to control the temperature to a lower temperature than before. 5. The image forming apparatus according to claim 4 , wherein the control unit sets the length of the first period based on a frequency of printing on the recording paper having the second width. The control unit performs the off control only when the frequency of printing on the recording paper having the second width is less than a predetermined value, and when the frequency is equal to or higher than the predetermined value, the standby period continues for a predetermined period. 6. The image forming apparatus according to claim 4, wherein preheating for the first region and the second region is controlled to be OFF or lower than before. Said heating means, said heater for heating the first region, the image forming apparatus according to any one of claims 1 to 6; and a heater for heating the second region. The heating means includes a heater that heats the first region and the second region, and a heater that heats only the first region of the first region and the second region. the image forming apparatus according to any one of claims 1 to 7, characterized in.

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