JP2017037147A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image quality from deteriorating even in a case where heating units are used by switching.SOLUTION: An image formation apparatus 100 includes: a power supply switch 101; an image formation unit 78 which forms a toner image on a recording material P; a first heating unit 8 which heats the toner image formed on the recording material P by the image formation unit 78; a second heating unit 9 which is provided on the downstream side with respect to the first heating unit 8 in the conveyance direction of the recording material P and heats the toner image on the recording material P heated by the first heating unit 8; a first temperature detection unit 42a which detects the temperature of the first heating unit 8; a second temperature detection unit 43a which detects the temperature of the second heating unit 9; and a control unit 81 which controls the adjustment operation of the image formation unit 78 following turning-on of the power supply switch 101 on the basis of the first temperature detected by the first temperature detection unit 42a following turning-on of the power supply switch 101 and the second temperature detected by the second temperature detection unit 423a following turning-on of the power supply switch 101.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an electrophotographic image forming apparatus.

  In an electrophotographic image forming apparatus, various adjustment controls are performed in order to maintain the quality of an output image. In particular, in an image forming apparatus that has been turned on after a while since the power of the image forming apparatus was turned off, the density of an image that is output due to a decrease in the charge amount of toner or environmental fluctuations around the image forming apparatus. There is a risk of affecting. For this reason, after the power is turned on for a while after the image forming apparatus is turned off, a process of performing a calibration operation and stabilizing the image density is performed before the first printing is started.

  Further, the electrophotographic image forming apparatus is provided with a fixing device (heating unit) that heats an unfixed toner image formed on a recording material. In order to obtain a higher quality product, there is known a method in which a fixing device having a different purpose of use is exchanged depending on the size and type of a recording material to be fixed. Japanese Patent Application Laid-Open No. 2004-151858 proposes a method for identifying the type of fixing device and notifying a user when a fixing device that is inappropriate for a recording material used for a print job is recognized.

JP 2008-58365 A

  As one of means for determining whether or not the image forming apparatus is turned on for a while after the power of the image forming apparatus is turned off when the power is turned on, there is a method of judging based on the temperature information of the fixing device. However, in this method, when a system in which a plurality of fixing devices are replaced is used, there is a possibility that printing may be started without performing calibration that should be performed. As a result, the image quality of the output may be deteriorated.

  Therefore, an object of the present invention is to suppress deterioration in image quality even when the heating unit is replaced.

In order to achieve the above object, the first invention provides:
An image forming apparatus for forming an image,
A power switch for starting the image forming apparatus;
An image forming unit for forming a toner image on a recording material;
A first heating unit for heating the toner image formed on the recording material by the image forming unit;
A second heating unit that is provided downstream of the first heating unit in the conveyance direction of the recording material and that heats the toner image on the recording material heated by the first heating unit;
A first temperature detection unit for detecting a temperature of the first heating unit;
A second temperature detection unit for detecting the temperature of the second heating unit;
The power switch based on the first temperature detected by the first temperature detector when the power switch is turned on and the second temperature detected by the second temperature detector when the power switch is turned on. A control unit for controlling the adjustment operation of the image forming unit when the is turned on;
It is characterized by having.

The second invention is
An image forming apparatus for forming an image,
A power switch for starting the image forming apparatus;
An image forming unit for forming a toner image on a recording material;
A first heating unit for heating the toner image formed on the recording material by the image forming unit;
A second heating unit that is provided downstream of the first heating unit in the conveyance direction of the recording material and that heats the toner image on the recording material heated by the first heating unit;
A first temperature detection unit for detecting a temperature of the first heating unit;
A second temperature detection unit for detecting the temperature of the second heating unit;
The power switch based on the first temperature detected by the first temperature detector when the power switch is turned on and the second temperature detected by the second temperature detector when the power switch is turned on. A control unit that controls whether or not to perform the adjustment operation of the image forming unit when the is turned on,
It is characterized by having.

  According to the present invention, it is possible to suppress deterioration in image quality even when the heating unit is replaced and used.

1 is a cross-sectional view illustrating an example of a configuration of an image forming apparatus. FIG. 3 is a cross-sectional view illustrating an example of a configuration of a fixing device. 2 is a block diagram illustrating an example of a control system of the image forming apparatus. FIG. (A) is a diagram showing an example of a fixing device dedicated to the type of recording material, and (b) is a diagram showing an example of a fixing device dedicated to the width size of the recording material. It is a figure which shows an example of the control content of the adjustment operation for morning, and a simple adjustment operation. It is a figure explaining gradation correction. It is a figure which shows the example of the several image (pattern image) from which density differs. It is a figure which shows the example of the image (pattern image) for position adjustment. 6 is a flowchart from when the power switch is turned on until the standby mode is set. 6 is a flowchart from when the power switch is turned on until the standby mode is set.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the components described in this embodiment are merely examples, and the present invention is not limited to only those described in the embodiment.

[Example 1]
[Configuration of Image Forming Apparatus]
FIG. 1 is a cross-sectional view showing an example of the configuration of the image forming apparatus.

  Note that the image forming apparatus of the present embodiment can be applied to a copying machine, a printer, a facsimile machine, and a multifunction machine having a plurality of these functions.

  First, the image forming unit 78 will be described.

  An image forming apparatus 100 shown in FIG. 1 is a full-color image forming apparatus using an electrophotographic method. Four stations Pa (yellow), Pb (magenta), Pc (cyan), and Pd (black) that form toner images of four different colors are arranged. Adjacent to these stations, an endless intermediate transfer belt 130 is disposed as an intermediate transfer member to which the toner images of the respective colors formed at the stations are transferred. Since these four stations Pa, Pb, Pc, and Pd have the same configuration, the configuration of the yellow station Pa will be described below as a representative. For other stations, the same components as those in the station Pa are given the same numbers, and the subscripts (a, b, c, d) indicating the respective units are changed.

  The photosensitive drum 3a as an image carrier is a cylindrical electrophotographic photosensitive member whose surface layer is made of an organic optical semiconductor, for example, and is driven to rotate in the direction of an arrow.

  As a forming unit that forms a toner image on the photosensitive drum 3a (on the image carrier), a charging roller (charging unit) 2a, an exposure device (exposure unit) La, and a developing device (developing unit) 1a function. The charging roller 2a is a charging unit (charging unit) that uniformly charges the surface of the photosensitive drum 3a. The charging roller 2a, to which a predetermined bias is applied, is driven to rotate while being in contact with the photosensitive drum 3a, thereby charging the surface of the photosensitive drum 3a to a predetermined potential. The exposure device La as an exposure means (exposure unit) exposes the charged photosensitive drum 3a, thereby electrostatically corresponding to an image of a portion requiring yellow toner in image information input from a scanner or an external terminal. A latent image is formed. In this example, the exposure apparatus La emits laser light. A developing device 1a as a developing unit (developing unit) includes a developing container that contains a developer containing toner and a carrier, and a stirring screw (see FIG. 1) for supplying toner to the developing sleeve while stirring the developer in the developing container. 1 and 2) and a developing sleeve. The developing device 1a develops the electrostatic latent image on the photosensitive drum 3a using toner carried on the developing sleeve, and forms a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 3a.

  The toner image on the photosensitive drum 3a is conveyed to the primary transfer portion (transfer portion) by the rotation of the photosensitive drum 3a, and a primary transfer bias is applied to the primary transfer roller 24a, whereby the toner image on the intermediate transfer belt 130 ( Primary transfer onto the intermediate transfer member).

  The primary transfer residual toner remaining on the photosensitive drum 3a without being subjected to the primary transfer is removed and collected by a cleaning device 4a provided with a blade or a brush. The photosensitive drum 3a from which the primary transfer residual toner has been removed is uniformly charged again by the charging roller 2a and repeatedly used for image formation.

  The intermediate transfer belt 130 is stretched around the drive roller 15, the support roller 13, and the backup roller 14. The intermediate transfer belt 130 is rotationally driven in the direction of arrow A by the rotation of the driving roller 15 while contacting the photosensitive drums 3a, 3b, 3c, and 3d of the four stations Pa, Pb, Pc, and Pd.

  When the full color mode (full color image formation) is selected, the image forming operation as described above is executed in each of the four stations Pa, Pb, Pc, and Pd. Then, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image respectively formed on the photosensitive drums 3a, 3b, 3c, and 3d are sequentially placed on the intermediate transfer belt 130 (on the intermediate transfer member). Multiple transcribed. Note that the color order is not limited to the above, and is arbitrary depending on the image forming apparatus.

  The four-color toner images transferred onto the intermediate transfer belt 130 are transferred to a secondary transfer portion (transfer portion) in which the backup roller 14 and the secondary transfer roller 11 are arranged to face each other via the intermediate transfer belt 130. Be transported. In the secondary transfer portion, a secondary transfer bias is applied to the secondary transfer roller 11, whereby the toner image on the intermediate transfer belt 130 is secondarily transferred to the recording material P. The recording material P is a sheet material such as paper or an OHP sheet. The storage cassette 10 is a storage unit that stores the recording material P. The single recording material P fed from the storage cassette 10 is fed to the timing at which the toner image on the intermediate transfer belt 130 is conveyed to the secondary transfer unit by the feeding device having the registration roller pair 12. Supplied to the secondary transfer unit.

  When viewed in the rotational direction A of the intermediate transfer belt 130, a cleaning device 22 for the intermediate transfer belt 130 is provided at a position between the secondary transfer portion and the primary transfer portion of the station Pa. The cleaning device 22 is provided with a blade, a brush, a web (nonwoven fabric) or the like, and removes and collects secondary transfer residual toner which is not after the secondary transfer and remains on the intermediate transfer belt 130. The cleaning device 22 in FIG. 1 is an example in which a web (nonwoven fabric) is disposed. The intermediate transfer belt 130 from which the secondary transfer residual toner has been removed is repeatedly used for image formation.

  A plurality of storage cassettes 10 may be provided so that the recording material P can be stored for each type and size. In this case, the CPU 81 (see FIG. 3) as the control unit records from the storage cassette in which the recording material P to be printed is stored according to the type of the recording material P specified by the user in the print job (printing command). The material P is conveyed by the feeding device. Further, the image forming apparatus 100 may be configured such that a user can select a storage cassette in a print job (print command).

  In the print job, in addition to the image data to be formed on the recording material P, various information such as color number information indicating whether the image is printed in color or monochrome, and the paper type of the recording material P are accepted.

  In this embodiment, the image forming unit 78 that forms an image on the recording material P (on the recording material) is configured as described above.

  Next, the fixing device will be described.

  The image (toner image) formed on the recording material P by the image forming unit 78 described above, that is, the toner image transferred to the recording material by the secondary transfer unit is conveyed to the fixing device. The fixing device 8 (first heating unit) and the fixing device 9 (second heating unit) apply heat and pressure to transfer the toner image transferred to the recording material P by the secondary transfer unit to the recording material P. Fix it on top. Here, the fixing device 8 and the fixing device 9 are detachably provided on the main body 100A of the image forming apparatus 100, respectively.

  In this embodiment, first, the recording material P to which the toner image has been transferred is introduced into the fixing device 8 provided upstream in the conveyance direction of the recording material P, and the unfixed toner image on the recording material P is pressurized and applied. Heated.

  After passing through the fixing device 8, the CPU 81 determines whether the recording material P is conveyed to the fixing device 9 (tandem fixing route) or the recording material P is conveyed around the fixing device 8 (bypass route). ) To switch.

  The fixing device 9 is arranged downstream of the fixing device 8 with respect to the conveyance direction of the recording material P. The fixing device 9 gives gloss to the toner image on the recording material P to which heat and pressure have been applied by the fixing device 8 or is used for the recording material P having a large basis weight that requires a large amount of heat for the fixing process. It is used for the purpose of compensating for the amount of heat that is insufficient with the fixing device 8 alone. Therefore, when the recording material P is thick paper or glossy paper, it is conveyed by a tandem fixing route.

  On the other hand, when fixing is possible only by the fixing device 8, the fixing device 9 does not have to be used. Therefore, the recording material P is conveyed through the conveying path 30 without going through the fixing device 9 for the purpose of reducing energy consumption. The For example, when the recording material P is plain paper, thin paper, or an envelope, the recording material P is conveyed by a bypass route.

  In the case of single-sided printing, the recording material P passes through the fixing device 9 or the conveyance path 30 and then passes through the conveyance path 31 and is discharged to a discharge tray installed outside the image forming apparatus 100.

  In the case of duplex printing, in order to form an image on the back side, the recording material P having a toner image fixed on one side is conveyed to the conveyance path 32 and reversed by the reversal path 33. Thereafter, the recording material P is conveyed again to the secondary transfer portion via the double-sided conveyance path 34, and a toner image is formed and fixed on the back side by the same process as described above.

  Next, a configuration example of the fixing device will be described. FIG. 2 is a cross-sectional view illustrating an example of the configuration of the fixing device. Here, the fixing device 8 will be described as an example.

  The image forming apparatus 100 employs a so-called oil-less fixing device by using a toner containing a release agent.

  The fixing device 8 includes a fixing roller 40 as a rotatable heating rotator that contacts the surface of the recording material P on which the toner image (unfixed) is formed and heats the toner image on the recording material P. Further, it has a pressure roller 41 as a rotatable nip forming member that forms a nip with the fixing roller 40.

  The fixing device 8 heats the fixing roller 40 with a heater 40a as a first heat source provided therein. The fixing device 8 sandwiches and conveys the recording material P carrying the toner image at the nip, thereby heating and pressurizing the recording material P to melt and fix the toner image on the recording material P. The heater 40a is, for example, a halogen heater. More specifically, the heater 40a is electrically connected to a heater control unit 90 (see FIG. 3) of the fixing device 8 provided in the fixing device 8. The heater control unit 90 of the fixing device 8 is a control circuit that controls ON / OFF of the heater 40a. The thermistor 42 a is a temperature sensor that detects the temperature of the surface of the fixing roller 40. More specifically, the thermistor 42 a is electrically connected to a temperature detector 89 (see FIG. 3) of the fixing device 8 provided in the fixing device 8 and detects the temperature of the surface of the fixing roller 40. The heater control unit 90 of the fixing device 8 and the temperature detection unit 89 of the fixing device 8 are electrically connected to the CPU 81. The CPU 81 (see FIG. 3) as the control unit controls the operation of the heater control unit 90 of the fixing device 8 based on the temperature detected by the temperature detection unit 89 of the fixing device 8, so that the temperature of the fixing roller 40 is the target. Adjust so that the temperature becomes.

  In this embodiment, the heater 40a heats the fixing roller 40 so that the surface of the fixing roller 40 maintains a temperature at which the toner image can be fixed to the recording material P, for example, about 150 to 180 ° C. The CPU 81 causes the heater 40a to heat the fixing roller 40 so that the surface temperature of the fixing roller 40 becomes a target temperature corresponding to the type of the recording material P.

  In this embodiment, the heater 40a is provided in the fixing roller 40. However, the present invention is not limited to this. For example, the heater 40a may be configured to heat the fixing roller 40 from the outside.

  In this embodiment, the heater 40a is composed of a halogen heater. However, the present invention is not limited to this, and any heater that can heat the fixing roller 40 such as a structure that is heated by induction heating may be used.

  The fixing roller 40 is formed by providing an elastic layer 40c made of a rubber layer on a metal hollow core shaft 40b as a base layer, and further covering a release layer 40d as a surface layer thereon. The core shaft 40b is made of, for example, an aluminum member formed in a cylindrical shape with an outer diameter of 68 mm, and the heater 40a is disposed inside. The elastic layer 40c is made of, for example, a silicone rubber having a JIS-A hardness of 20 degrees molded with a thickness of 1.0 mm. The release layer 40d is made of a material that is excellent in release properties and softens when the temperature rises, such as a fluororesin molded to a thickness of 50 μm, for example, and covers the elastic layer 40c. For the release layer 40d, for example, PFA resin (tetrafluoroethylene resin, copolymer of perfluoroalkoxyethylene resin), PTFE (tetrafluoroethylene resin), or the like is used as the fluororesin. In this example, a PFA resin tube was used as the release layer 40d. The thickness of the release layer 40d, which is the surface layer of the fixing roller 40, is preferably configured to be 30 μm to 100 μm, for example. Here, the release layer 40d is not limited to the tube shape, and for example, the elastic layer 40c may be covered by coating the elastic layer 40c.

  The fixing roller 40 is rotatably supported by support members (not shown) provided at both ends in the longitudinal direction (rotation axis direction) of the core shaft 40b, and is indicated by an arrow in FIG. 2 by a motor 92 (see FIG. 3). Is driven to rotate. By being driven by the motor 92, the fixing roller 40 is rotationally driven at a surface moving speed of, for example, 100 mm / sec. The motor 92 is electrically connected to the motor control unit 91 of the fixing device 8 provided in the fixing device 8. The motor control unit 91 of the fixing device 8 is electrically connected to the CPU 81 and controls the rotation of the motor 92 in accordance with a command from the CPU 81. That is, the CPU 81 controls the rotation of the fixing roller 40 via the motor control unit 91 of the fixing device 8. In the following description, the surface moving speed of each rotating body is also referred to as a peripheral speed.

  The pressure roller 41 is formed by providing an elastic layer 41c made of a rubber layer on a metal hollow core shaft 41b as a base layer, and further covering a release layer 41d as a surface layer thereon. The core shaft 41b is made of, for example, an aluminum member formed in a cylindrical shape having an outer diameter of 48 mm. The elastic layer 41c is made of, for example, a silicone rubber having a JIS-A hardness of 20 degrees molded with a thickness of 2.0 mm. The release layer 41d is made of a material having excellent release properties such as a fluororesin molded to a thickness of 50 μm, for example, and covers the elastic layer 41c. Here, the release layer 41d is not limited to the configuration according to the present embodiment in the same manner as the release layer 40d of the fixing roller 40 with respect to the material and the configuration covering the elastic layer 41c.

  A heater 41 a such as a halogen heater is also arranged inside the pressure roller 41. The pressure roller 41 is a heating rotator that applies heat to the recording material P from the back side of the recording material P (the surface opposite to the surface on which the unfixed toner image of the recording material P is formed). The surface of the pressure roller 41 is provided with a thermistor 42 b that detects the temperature of the surface of the pressure roller 41. More specifically, the heater 41a is electrically connected to a heater control unit 90 (see FIG. 3) of the fixing device 8 provided in the fixing device 8. The heater control unit 90 of the fixing device 8 is a control circuit that controls ON / OFF of the heater 41a. The thermistor 42 b is electrically connected to a temperature detector 89 (see FIG. 3) of the fixing device 8 provided in the fixing device 8, and detects the temperature of the surface of the pressure roller 41. The heater control unit 90 of the fixing device 8 and the temperature detection unit 89 of the fixing device 8 are electrically connected to the CPU 81. The CPU 81 (see FIG. 3) serving as a control unit controls the operation of the heater control unit 90 of the fixing device 8 based on the temperature detected by the temperature detection unit 89 of the fixing device 8, thereby controlling the temperature of the pressure roller 41. Adjust to the target temperature. For example, the pressure roller 41 is adjusted so that the temperature becomes 100 ° C.

  The pressure roller 41 is rotatably supported by support members (not shown) provided at both ends in the longitudinal direction (rotation axis direction) of the core shaft 41b. Further, the supporting members at both ends in the longitudinal direction of the pressure roller 41 are urged by pressure springs (not shown) as urging means, so that the pressure roller 41 is connected to the fixing roller 40 and the recording material P. A nip having a predetermined width is formed in the conveying direction. Further, the pressure roller 41 is rotated by following the fixing roller 40 by contacting the fixing roller 40 in this way. In this embodiment, the pressure roller 41 is pressed against the fixing roller 40 with, for example, a total pressure of 400N.

  In the above description, the fixing device 8 has been described as an example, but the same applies to the fixing device 9. The fixing device 9 also includes a fixing roller 46 as a rotatable heating rotator that heats the toner image on the recording material P, and a pressure roller (heated rotation) as a rotatable nip forming member that forms a nip with the fixing roller 46. Body) 47. The fixing roller 46 is heated by a heater provided therein, and the pressure roller 47 is heated by a heater provided therein. A heater 75 in FIG. 3 shows these heaters, and the heater 75 is electrically connected to a heater control unit 72 (see FIG. 3) of the fixing device 9 provided in the fixing device 9. The heater control unit 72 of the fixing device 9 is a control circuit that controls ON / OFF of the heater 75. The thermistor 43 a is a temperature sensor that detects the temperature of the surface of the fixing roller 46. More specifically, the thermistor 43 a is electrically connected to a temperature detector 71 (see FIG. 3) of the fixing device 9 provided in the fixing device 9 and detects the temperature of the surface of the fixing roller 46. The heater control unit 72 of the fixing device 9 and the temperature detection unit 71 of the fixing device 9 are electrically connected to the CPU 81. The CPU 81 (see FIG. 3) as a control unit controls the operation of the heater control unit 72 of the fixing device 9 based on the temperature detected by the temperature detection unit 71 of the fixing device 9, so that the temperature of the fixing roller 46 is the target. Adjust so that the temperature becomes. The surface of the pressure roller 47 is provided with a thermistor 43 b that detects the temperature of the surface of the pressure roller 47. More specifically, the thermistor 43 b is electrically connected to a temperature detector 71 (see FIG. 3) of the fixing device 9 provided in the fixing device 9 and detects the temperature of the surface of the pressure roller 47. . The CPU 81 (see FIG. 3) as the control unit controls the heater control unit 72 of the fixing device 9 based on the temperature detected by the temperature detection unit 71 of the fixing device 9, so that the temperature of the pressure roller 47 becomes the target temperature. Adjust so that Since other configurations are the same as those of the fixing device 8, the description thereof is omitted. The nip width, the pressure applied by the pressure roller 47 to the fixing roller 46, and the like may be different from those of the fixing device 8.

  The power switch 101 is a start switch (hard switch) for starting the image forming apparatus 100.

[Control unit]
FIG. 3 is a block diagram illustrating an example of a control system of the image forming apparatus.

  The image forming apparatus 100 includes a CPU 81, a RAM 82, a ROM 83, and the like for controlling the operation of the image forming apparatus 100.

  The CPU 81 functioning as a control unit performs basic control of the image forming apparatus 100 by executing a control program stored in the ROM 83. The operation of the flowchart described below is executed by the CPU 81 based on a control program stored in the ROM 83. The CPU 81 uses the RAM 82 as a work area for executing control program processing.

  The RAM 82 is a non-volatile memory and also functions as a memory (storage unit) that stores a gradation correction table and the like.

  The CPU 81 is electrically connected to each mechanism to be controlled in addition to the RAM 82 and ROM 83.

  In a state where the fixing device 8 is mounted on the image forming apparatus 100, the CPU 81 as a control unit controls each control unit of the fixing device 8 (temperature detection unit 89 of the fixing device 8, heater control unit 90 of the fixing device 8, fixing). The motor control unit 91) of the apparatus 8 is electrically connected. The CPU 81 controls each control unit of the fixing device 8 to control the conveyance speed of the recording material P in the fixing device 8 and the temperatures of the fixing roller 40 and the pressure roller 41. Thus, the CPU 81 can cause the fixing device 8 to execute processing for fixing the toner image on the recording material P. In a state where the fixing device 9 is mounted on the image forming apparatus 100, the CPU 81 as a control unit controls each control unit of the fixing device 9 (temperature detection unit 71 of the fixing device 9, heater control unit 72 of the fixing device 9, fixing). The motor control unit 73) of the apparatus 9 is electrically connected. Similar to the fixing device 8, the CPU 81 can execute processing for fixing the toner image on the recording material P by controlling each control unit of the fixing device 9.

  The CPU 81 is electrically connected to the transport unit 77 and controls the transport of the recording material P. The conveyance unit 77 includes a feeding unit that feeds the recording material P from the storage cassette 10, a feeding device having the registration roller pair 12, various flappers that switch the conveyance path, and the like.

  The CPU 81 is electrically connected to the image forming unit 78 and controls the image forming unit 78. As described above, the image forming unit 78 includes various mechanisms included in the stations Pa, Pb, Pc, and Pd, mechanisms such as a primary transfer unit and a secondary transfer unit, and the cleaning device 22.

  The CPU 81 is electrically connected to the operation unit 95. In this example, they are connected via the I / F unit 85. The operation unit 95 includes a display unit 94 (for example, a liquid crystal monitor) and a selection unit 93 (for example, a selection key). The display unit 94 may be a touch panel system that also serves as the selection unit 93. The operation unit 95 displays the operation state of the image forming apparatus 100 on the display unit 94 or receives an instruction from the user via the selection unit 93. The CPU 81 performs the control.

  The CPU 81 is connected to an input receiving unit 87 that functions as a receiving unit, and receives image information 88 that is a document of an image to be image-formed by the image forming apparatus 100 from the outside via the input receiving unit 87. The image information 88 is received via an input receiving unit 87 from an external PC connected via a network or the like. Note that the image forming apparatus 100 may be configured to receive a paper medium document as image data and the image information 88 may be received as the input receiving unit 87.

  The CPU 81 is connected to the image processing sensor 84. Here, the image processing sensor 84 indicates a density detection sensor 140 and a position adjustment sensor 141. The CPU 81 acquires output results of the density detection sensor 140 and the position adjustment sensor 141.

  The CPU 81 is electrically connected to the timer 86. The timer 86 measures the time for stirring the toner and the carrier in the developing container.

[Fixing device replacement system]
Next, a fixing device replacement system will be described. Hereinafter, the fixing device 8 will be described as an example.

  In recent years, the types of recording materials P on which images are formed are diversified according to the needs of various customers. For example, an envelope or a paper having a high basis weight. In order to obtain a higher quality product, a method has been proposed in which a plurality of fixing devices having different purposes of use are prepared, and the fixing devices are switched according to the type of recording material P to be printed and the user's preference. Yes. In this example, this method is referred to as a fixing device replacement system. By operating the image forming apparatus 100 by replacing the fixing device set corresponding to the recording material P to be used, a single image forming apparatus 100 can cope with more types of recording materials P. In this example, the fixing devices that can be replaced are both the fixing device 8 and the fixing device 9. When the type of the recording material P to be printed is a recording material conveyed by the bypass fixing route, the operator may replace only the fixing device 8 with a fixing device suitable for the purpose of use.

  For example, since it is ideal to apply a certain amount of heat to the toner image on the recording material P, when the thickness of the recording material P changes greatly, it is desirable to change the fixing conditions as well.

  Also, for example, there is a fixing device dedicated to envelopes. In order to transport the recording material P under pressure at the nip, for example, when the recording material P with uneven thickness, such as an envelope, is transported at a high pressure, the transport speed of the front and back surfaces of the envelope, the overlapping portion, etc. There is a difference. As a result, wrinkles and uneven gloss of the toner image after fixing may occur. Therefore, when printing an envelope as the recording material P, as the fixing device 8, a fixing device dedicated to the envelope in which the pressure at the nip portion is adjusted to a pressure suitable for the envelope is used.

  As described above, there is a method in which a plurality of fixing devices each set according to the type of the recording material P are prepared, and the fixing device 8 is replaced and used in accordance with the type of the recording material P to be printed and the user's preference. Proposed. In this example, this is referred to as a fixing device replacement system. By operating the image forming apparatus 100 by replacing the fixing device set corresponding to the recording material P to be used, a single image forming apparatus 100 can cope with more types of recording materials P.

  FIG. 4 shows an example of proper use of the fixing device 8 in the fixing device replacement system. 4A is a diagram illustrating an example of a fixing device dedicated to the type of recording material, and FIG. 4B is a diagram illustrating an example of a fixing device dedicated to the width size of the recording material.

  An example will be described with reference to FIG. As an example of proper use of the fixing device 8, there is proper use according to the type of the recording material P.

The fixing device A is widely compatible with more general types of recording materials P. This fixing device A is for normal use. When passing a sheet that is 4 to 5 times as large as a sheet of about 64 to 80 g / m ² that is relatively frequently used in a normal office, if the fixing device A is used as the fixing device 8, the fixing temperature is several tens of degrees Celsius. Even if it raises, there is a possibility that the amount of heat is insufficient. Further, since the thick recording material P is subjected to a large pressure at the nip portion, and the pressure difference between the passing region and the non-passing region of the recording material P is large, the stress on the fixing roller 40 and the pressure roller 41 is also large. Become. For this reason, there exists a possibility that deterioration and consumption of a member surface may be accelerated.

  Therefore, in the fixing device B, the thick recording material P is emphasized, the nip width is widened, and the pressure is dispersed. This fixing device B is used for cardboard. However, in the case of this setting, wrinkles and gloss unevenness may occur on the thin recording material P.

  When it is desired to fix the envelope well, the fixing device C designed so that the pressure is about half that of the fixing device A is used. By reducing the pressure, stress on the envelope can be reduced, and wrinkles and uneven gloss can be suppressed. This is for envelopes. In this case, when a normal recording material P or particularly a thick recording material P that requires heat is passed, a cold offset in which the toner is offset to the fixing roller 40 side or the surface property becomes rough without sufficiently melting the toner. There is a possibility that bad effects such as a decrease in glossiness may occur.

  As another example of proper use of the fixing device 8, there is a proper use according to the size of the recording material in a direction perpendicular to the conveyance direction of the recording material P (this is referred to as a width size). An example will be described with reference to FIG.

  When the recording material P having the same width is repeatedly passed through the nip, the surface roughness in the longitudinal direction on the fixing roller 40 and the pressure roller 41 (direction perpendicular to the conveying direction of the recording material P) is nonuniform. Specifically, when the recording material P having the same width size is repeatedly passed through the nip, fixing is performed by contact with an end portion (hereinafter referred to as an edge portion) of the recording material P in a direction perpendicular to the conveyance direction of the recording material P. The surface of the roller 40 or the pressure roller 41 is damaged. Further, in the passage region of the recording material P, the surface of the fixing roller 40 and the pressure roller 41 is leveled by the recording material P coming into contact with the fixing roller 40 and the pressure roller 41. Further, in the non-passage area of the recording material P, the fixing roller 40 and the pressure roller 41 are in contact with each other and are driven, so that the recording material P is not affected. As a result, the surface roughness of the fixing roller 40 and the pressure roller 41 is different in the longitudinal direction. In this state, when the fixing process is performed on the recording material P having a larger width size than the recording material P that has been repeatedly passed, the toner image on the recording material P is caused by uneven surface properties of the fixing roller 40 and the pressure roller 41. There is a risk that it will be visually recognized as uneven gloss. Therefore, by preparing a fixing device for each width size of the recording material P and exchanging it according to the width size of the recording material to be printed, the above-described gloss unevenness can be suppressed.

  FIG. 4B shows an example in which the fixing device 8 is selectively used depending on the width size of the recording material. Usually, the fixing device A is used. When paying particular attention to the glossiness of the product, the operator replaces the fixing device A with a dedicated fixing device D or fixing device E. For example, when the user handles both printing on a two-sided postcard-sized recording material P and printing of an A3 nobi image, the fixing device D (here, for a small size) is used for a two-sided postcard having a width of 200 mm. In the case of A3 Nobi printing, the fixing device E (for large size) is used. As a result, the fixing roller 40 and the pressure roller 41 can be fixed without contacting portions of the surface having different surface properties with the toner image on the recording material P, so that a product with reduced gloss unevenness can be obtained.

[Adjustment operation when the power switch is turned on]
When the power switch 101 is turned on by the operator, the image forming apparatus 100 performs an operation to start up the image forming process so that the image forming process can be started. Hereinafter, the operation for starting up the image forming process so that it can be started will be referred to as a start-up operation. For example, temperature adjustment control (hereinafter referred to as temperature control) for adjusting the fixing rollers 40 and 46 and the pressure rollers 41 and 47 to a temperature at which the fixing process can be started is one of them. In this start-up operation, in addition to the temperature control of the fixing roller 40 and the like, an adjustment operation in the image forming unit 78 is performed in order to execute the image forming process in an appropriate state.

  In this example, the content of the adjustment operation to be executed is controlled according to the state of the image forming apparatus 100 when the power switch 101 is turned on by the operator.

  If the image forming apparatus 100 is in the morning state when the power switch 101 is turned on by the operator, an adjustment operation for the morning is performed.

  On the other hand, when the state of the image forming apparatus 100 when the power switch 101 is turned on by the operator is a non-morning state, a simple adjustment operation is performed. The simple adjustment operation is an adjustment operation performed simply by omitting a part of the control content (adjustment items) performed in the morning adjustment operation or shortening the control time of the adjustment operation for the morning adjustment. .

  FIG. 5 is a diagram illustrating an example of control contents of the morning adjustment operation and the simple adjustment operation.

  Here, the morning one state refers to a state in which it is determined that the power switch 101 is turned on after a long time has passed since the power switch 101 was turned off. The non-morning state indicates a state in which it is determined that the power switch 101 has been turned on before a long time has passed since the power switch 101 was turned off. In addition, since the specific determination method of a morning one state and a non-morning one state is mentioned later, it abbreviate | omits here.

  While the power switch 101 is off, the mechanisms such as the image forming unit 78 and the fixing devices 8 and 9 do not operate. Therefore, when the power switch 101 is turned off for a long time, the charge amount per unit weight of toner (hereinafter simply referred to as the charge amount) decreases. When the image forming process is performed using the toner whose charge amount is still reduced, there is a risk that the density of the image formed on the recording material P is reduced or density unevenness occurs.

  Further, when the power switch 101 is turned off for a long time, it is more likely that the environment around the image forming apparatus 100 has changed than when the power switch 101 is off for a short time. For example, when used in an office, a situation is assumed in which the power switch 101 is turned off at night and the use of the image forming apparatus 100 is resumed in the morning when the power switch 101 is turned on at the start of business. The In daytime offices, the temperature and humidity of the room are often kept almost constant by an air conditioner or the like, but the air conditioner or the like is often turned off outside business hours. Therefore, immediately after the start of work in the morning, it is close to the state of temperature and humidity at night. And for the first few hours after the start of work, the temperature and relative humidity in an environment such as an air conditioner from a state close to nighttime temperature and humidity (hereinafter referred to simply as humidity unless otherwise specified) It is a time zone that changes rapidly. If the humidity / temperature environment fluctuates, the toner charge amount may be affected. As a result, the density stability of the toner image formed on the recording material P may be lowered.

  In order to suppress the influence on the image quality due to the power switch 101 being turned off, the adjustment operation for the morning is performed in the morning.

  On the other hand, even when the power switch 101 is turned on, if the time has not passed since the power switch 101 was turned off, the influence on the image quality is relatively small. Therefore, in the non-morning state, an adjustment operation in which a part of the morning adjustment operation is omitted or simplified, that is, a simple adjustment operation simpler than that in the morning is performed. For example, when the adjustment operation for one morning is performed over 2 to 3 minutes, the simple adjustment operation is an adjustment operation in which a part of the adjustment operation is omitted or simplified, so that it can be performed in a relatively short time (for example, 1 to 2 minutes). it can.

  In particular, when the power switch 101 is turned on immediately after it is turned off, the temperature of the members of the fixing devices 8 and 9 (such as the fixing roller 40) hardly decreases. It may be completed in a short time. In such a case, when the adjustment operation for the morning is executed as the adjustment operation, it takes about 1 to 2 minutes to complete the start-up operation, compared to the case where the simple adjustment operation is executed. Therefore, in the non-morning state, the simple adjustment operation that is simpler than that in the morning is performed, so that the time required for the adjustment operation in the start-up operation is shortened. As a result, it is possible to suppress an increase in the waiting time of the operator from when the power switch 101 is turned on by the adjustment operation until the image forming apparatus 100 becomes ready to start the image forming process.

  The CPU 81 controls whether the adjustment operation for the morning is executed or the simple adjustment operation is executed in the startup operation when the power switch 101 is turned on.

  The period in which the image forming apparatus 100 is ready to start image forming processing and is waiting for a print command (print job) from the operator is referred to as a standby mode. The CPU 81 shifts to the standby mode when the startup operation is completed. In the standby mode, the CPU 81 displays a message such as “printing is possible” on the operation unit (notification unit) 95 to notify the operator that the image forming process can be started. In the standby mode, the fixing device 8 and the fixing device 9 are controlled by the CPU 81 so that the temperature of the fixing roller 40 and the like is kept constant. This is because printing can be started immediately after receiving a print job. When a print reservation is made during the start-up operation, the CPU 81 executes the reserved print job without shifting to the standby mode when the start-up operation is completed. In this case, during execution of the print job, the CPU 81 displays a message such as “Printing in progress” on the operation unit (notification unit) 95 to notify the operator that the image forming process can be executed.

  Hereinafter, the adjustment operation of the image forming unit of the image forming apparatus 100 will be described specifically for each adjustment item. The morning adjustment operation and the simple adjustment operation will be described respectively. FIG. 5 shows an example of the control contents of the adjustment operation for the morning and the simple adjustment operation, in which the differences in the control contents described below are arranged.

[Adjustment Operation 1 of Image Forming Unit]
In electrophotographic image formation, the amount of toner on the image developed on the photosensitive drum 3a varies greatly depending on the charge amount of the toner. Therefore, stabilizing the toner charge amount is important for stabilizing the density of the image developed on the photosensitive drum 3a. Since the image on the photosensitive drum 3a is finally transferred to the recording material P, the density of the image on the recording material P that is output is affected by the charge amount of the toner. For example, if the other conditions are the same, if the charge amount of the toner is reduced, the amount of toner developed with a certain developing bias is increased, so that the density of the toner on the image on the recording material P is increased. The same applies to the photosensitive drums 3b, 3c, and 3d.

  In the image forming apparatus 100 of the present embodiment, a two-component development method using a developer containing toner (nonmagnetic) and carrier (magnetic) as the developer is employed. In the two-component developing method, the toner and the carrier are agitated by a screw provided in the developing container of the developing device 1a, so that the toner is triboelectrically charged. In the state where the power switch 101 is turned off, the toner and the carrier are not agitated in the developing device 1a, so that the charge amount decreases with the passage of time.

  Therefore, in the morning state, as one of the adjustment operations for the morning, the screw of the developing device 1a is rotationally driven. As a result, the toner and the carrier in the developing container are agitated to restore the charge amount. This is called idling. The stirring time is preset in the ROM 83 (for example, 10 seconds), and is measured by the timer 86.

  On the other hand, in the non-morning state, there is less decrease in the charge amount with the passage of time than in the morning state. Therefore, in the non-morning state, a simple idling is performed in which the stirring time is shorter than the idling process described above. That is, it is simplified. The stirring time is preset in the ROM 83 (for example, 3 seconds), and is measured by the timer 86.

  In this example, the simple idling is executed in the non-morning state. However, in the non-morning state, the screw of the developing device 1a is not driven to rotate (that is, the idling is omitted). Also good.

[Adjustment operation 2 of image forming unit]
The image forming apparatus 100 adjusts the image forming conditions of the image forming unit 78 in order to suppress the influence on the quality of the product due to the power switch 101 being turned off for a long time, and forms an image based on the adjusted image forming conditions. It is desirable to cause the portion 78 to perform image formation.

  For example, the environment (temperature / humidity) around the image forming apparatus 100 may affect the quality of the product. When the environment surrounding the toner (relative humidity or absolute humidity determined by the relative humidity and temperature) fluctuates, the charge amount of the toner changes. As a result, the density of the image to be developed changes, and there is a risk that the stability of the density of the image is lowered. As described above, for example, when the image forming apparatus 100 is used in an office, the temperature / humidity at night immediately after the start of work in the morning when the air conditioner is turned on (during work) / off (out of work hours). Close to the environment. For this reason, the charge amount of the toner is different from that in the daytime temperature and humidity environment on the previous day, and the density of the image to be developed changes.

  In view of this, the image forming apparatus 100 performs density adjustment control for adjusting the output image density as one of the adjustment operations for the morning when in the morning in order to perform image formation under a more appropriate image forming condition. I do. Thus, the image forming apparatus 100 determines the image forming conditions in the image forming process after the start-up operation is completed. The image forming unit 78 performs image formation under the determined image forming conditions. That is, the image information 88 input after the morning adjustment operation or the simple adjustment operation is subjected to image formation processing under the image formation conditions determined by the adjustment operation.

  The image forming apparatus 100 performs gradation correction in order to form an image with an appropriate density on the input document image. FIG. 6 is a diagram for explaining gradation correction, and shows the correspondence between signal values and density values. It is assumed that the gradation characteristic of an image formed by the image forming apparatus 100 is a broken line (a curve indicated by a broken line in FIG. 6) with respect to the ideal gradation characteristic (a straight line in FIG. 6). The gradation correction table (curve indicated by a solid line in FIG. 6) corrects the broken-line gradation characteristic (dashed curve in FIG. 6) to an ideal gradation characteristic (straight line in FIG. 6). This gradation correction table is stored in the RAM 82. Image information 88 input to the image forming apparatus 100 is converted by a CPU (conversion unit) 81 based on this gradation correction table. The image forming unit 78 forms an image based on the output value (output data) converted based on the gradation correction table.

  The density adjustment control is control for determining a gradation correction table used for image formation based on a plurality of images (referred to as patch images or pattern images) having different densities formed by the image forming unit 78.

  Specifically, the CPU 81 causes the image forming unit 78 to form a plurality of pattern images having different densities, and measures the density of the pattern image based on the output of the density detection sensor 140 that functions as a density detection unit. Image data for forming a pattern image is stored in the RAM 82 in advance. The pattern image may be measured on each of the photosensitive drums 3a, 3b, 3c, and 3d, or may be formed on the intermediate transfer belt 130 or the recording material P and measured. The CPU 81 as a determining unit determines a gradation correction table used for image formation based on the density. Here, the gradation correction table may be configured to be created by the CPU 81 based on a plurality of different pattern images, or by correcting (correcting) the provisional gradation correction table that has already been created, image formation is possible. It is good also as a structure used as the gradation correction table to be used. In the latter case, the CPU 81 as the determination unit also functions as a correction unit. A provisional gradation correction table is stored in the RAM 82. The determined gradation correction table is stored in the RAM 82. In the image forming process, the CPU 81 controls the image forming unit 78 based on the output value converted based on the gradation correction table. For example, the exposure time of the exposure apparatuses La, Lb, Lc, and Ld is controlled.

  In this example, the CPU 81 controls the stations Pa, Pb, Pc, and Pd, and a plurality of pattern images having different densities on each of the photosensitive drums 3a, 3b, 3c, and 3d (five levels with five densities for each color). Image) is formed and transferred to the intermediate transfer belt 130. A density detection sensor 140 provided at a position facing the outer peripheral surface of the intermediate transfer belt 130 detects the density of the pattern image. The CPU 81 determines a gradation correction table to be used for image formation based on the density.

  FIG. 7 is a diagram illustrating an example of a plurality of images (pattern images) having different densities. FIG. 7 shows an example in which pattern images (X in the figure) having different densities are formed on the intermediate transfer belt 130 for one color toner (for example, magenta).

  On the other hand, in the non-morning state, since the time elapsed after the power switch 101 is turned off is shorter than in the morning state, the environment (particularly humidity (absolute humidity)) surrounding the toner is smaller than in the morning state. The fluctuation is assumed to be small. As a result, the change in the toner charge amount is assumed to be smaller than that in the morning. Therefore, simple density adjustment control that is simpler than density adjustment control in the morning state is performed.

  Specifically, the number of pattern images to be formed is reduced by density adjustment control, and simple image forming conditions are corrected based on the density of a small pattern image (a gradation correction table is determined by a simple adjustment operation). . Details will be described below. For example, by correcting (correcting) a provisional gradation correction table that has already been created, a gradation correction table used for image formation is obtained. At this time, the provisional gradation correction table is stored in the RAM 82. For example, in the density adjustment control, five pattern images having different densities per color are formed, but in the simple density adjustment control, three pattern images having different densities are used per color. The pattern image data used in the simple density adjustment control is stored in the RAM 82 in advance. By reducing the number of pattern images formed, the time required for pattern image formation can be shortened.

  In this example, the simple density adjustment control is executed in the non-morning state. However, in the non-morning state, a pattern image may not be formed (that is, the density adjustment control is omitted). . In this case, image forming processing is performed based on the most recently used gradation correction table.

[Adjustment Operation 3 of Image Forming Unit]
As another example of the control for adjusting the image forming conditions of the image forming unit 78, there is a position adjustment control for suppressing the positional deviation of the toner image between four colors (yellow, magenta, cyan, black). A yellow toner image, a magenta toner image, a cyan toner image, and a black toner image respectively formed on the photosensitive drums 3 a, 3 b, 3 c, and 3 d are sequentially transferred onto the intermediate transfer belt 130 in a multiple transfer manner. Form an image. If the position of the image transferred onto the intermediate transfer belt 130 is deviated between the four colors, the product image is disturbed, leading to a reduction in quality.

  Therefore, in the case of the morning one state, the position adjustment is controlled as one of the morning adjustment operations. Specifically, the CPU 81 controls the image forming unit 78 to form a pattern image for alignment on the intermediate transfer belt 130, and is used for position adjustment provided at a position facing the outer peripheral surface of the intermediate transfer belt 130. The position of the pattern image is detected based on the output of the sensor 141. The CPU 81 corrects the image forming conditions of the image forming unit based on the detection result. For example, the exposure timing in the exposure apparatuses La, Lb, Lc, and Ld is corrected and adjusted so that an image can be formed at a desired position.

  A plurality of pattern images are formed so as to be spaced apart from each other in the circumferential direction of the intermediate transfer belt 130, for example, as indicated by Y in FIG. FIG. 8 is a diagram illustrating an example of a position adjustment image (pattern image). The pattern image data to be formed is stored in the RAM 82 in advance. The CPU 81 measures whether the intermediate transfer belt 130 is misaligned in the transport direction by measuring whether the pattern image passes the position adjustment sensor 141 at a predetermined timing based on the output of the position adjustment sensor 141. Detect. Further, a line sensor that covers the width of the pattern image in the main scanning direction (direction corresponding to the longitudinal direction of the photosensitive drum) is used as the position adjustment sensor 141. The CPU 81 detects the position of the pattern image in the main scanning direction based on the output of the position adjustment sensor 141 in the main scanning direction of the pattern image.

  On the other hand, in the non-morning state, a pattern image is not formed (that is, position control is omitted). This eliminates the time required for pattern image formation, position detection, correction, and the like.

[Other adjustment operations]
In this example, three examples of the adjustment operation of the image forming unit are given, but the adjustment operation of the image forming unit is not limited to the above. That is, another adjustment may be performed as an adjustment operation for the morning. For example, the adjustment operation for the morning may be configured to adjust the transfer voltage or the toner supply amount to the developing container. In this case, similarly to the above-described example, in the case of a non-morning state, a part of the morning adjustment operation may be omitted or simplified as the simple adjustment operation.

  In addition, in this example, in the non-morning state, a simple adjustment operation is performed by omitting or simplifying part of the adjustment operation for the morning. The configuration may be such that the adjustment operation for the morning is not executed. That is, in the case of a non-morning state, all of the adjustment operations for the morning may be omitted. For example, assume that two adjustment items of idling and patch image formation for density adjustment are executed as the adjustment operation for the morning in the start-up operation in the morning one state. In this case, in the start-up operation in the non-morning state, the standby mode is entered without executing either idling or patch image formation for density adjustment. Since the time required for the adjustment operation in the start-up operation in the non-morning state is eliminated, the operator's operation from when the power switch 101 is turned on by the adjustment operation until the image forming apparatus 100 can start the image forming process. It can suppress that waiting time becomes long.

[Morning method in the morning and issues in the re-loading system]
The image forming apparatus 100 of this example determines whether it is in the morning state or in the non-morning state based on the temperatures of the fixing device 8 and the fixing device 9 mounted on the main body 100A of the image forming apparatus 100. Specifically, when at least one of the temperature of the fixing device 8 and the temperature of the fixing device 9 is equal to or lower than a predetermined temperature (50 ° C. in this example), the CPU 81 determines that the image forming apparatus 100 is in the morning. When both the temperature of the fixing device 8 and the temperature of the fixing device 9 exceed a predetermined temperature (50 ° C. in this example), the CPU 81 determines that the image forming apparatus 100 is in a non-morning state.

  In a state where the power switch 101 is turned on, the temperature of the fixing roller 40 and the pressure roller 41 of the fixing device 8 is constant even in the standby mode so that the CPU 81 can start printing immediately after receiving a print job. The temperature is controlled to be maintained. For example, the temperature in the standby mode is controlled so that the fixing roller 40 is 150 ° C. and the pressure roller 41 is 100 ° C. On the other hand, when the power switch 101 is turned off, the temperature of the fixing device 8 is not controlled, and the heaters 40a and 41a included in the fixing device 8 are turned off. Thereafter, while the power switch 101 is turned off, the heaters 40a and 41a of the fixing device 8 are turned off.

  Accordingly, when the power switch 101 is turned off, the temperature of the fixing roller 40 and the pressure roller 41 of the fixing device 8 gradually decreases as time passes, and after several hours, the temperature around the image forming apparatus 100 ( For example, about 20 ° C.). As described above, when a long time elapses after the power switch 101 is turned off, the charge amount of the toner is decreased, or the density stability is decreased due to a change in the humidity and temperature environment around the image forming apparatus 100. There is a risk of doing so.

  On the other hand, when the power switch 101 is turned on within a short time after the power switch 101 is turned off (for example, immediately after the power switch 101 is turned off), the fixing roller 40 and the pressure roller 41 of the fixing device 8 are turned on. The temperature does not drop relatively.

  The same applies to the fixing device 9.

  Therefore, when either the temperature of the fixing device 8 or the temperature of the fixing device 9 is equal to or lower than a predetermined temperature, the CPU 81 assumes that a certain time has passed since the power switch 101 is turned off and the image forming apparatus 100 is in the morning state. Judge that there is. When both the temperature of the fixing device 8 and the temperature of the fixing device 9 exceed a predetermined temperature, the CPU 81 assumes that the time has not passed since the power switch 101 is turned off, and the CPU 81 is in the non-morning state. Judge that there is. In this example, the predetermined temperature is 50 ° C. That is, when either the temperature of the fixing device 8 or the temperature of the fixing device 9 is 50 ° C. or less, the CPU 81 determines that the image forming apparatus 100 is in the morning state and causes the morning adjustment operation to be executed. When both the temperature of the fixing device 8 and the temperature of the fixing device 9 exceed 50 ° C., the CPU 81 determines that the image forming apparatus 100 is in a non-morning state, and executes a simple adjustment operation.

  Note that information on a predetermined temperature for determining whether or not it is in the morning is stored in the ROM 83 in advance. Further, this temperature is not limited to 50 ° C., and is set as appropriate according to the configuration of the image forming apparatus 100. In this example, the surface temperature of the fixing roller (heating rotator) 40 is used as the temperature of the fixing device 8 (first heating unit). The temperature of the fixing roller 40 is detected by the temperature detector 89 of the fixing device 8 based on the output of the thermistor 42a. The CPU 81 acquires the temperature of the fixing roller 40 from the temperature detection unit 89 of the fixing device 8. Further, the temperature of the surface of the fixing roller (heating rotator) 46 is used as the temperature of the fixing device 9 (second heating unit). The temperature of the fixing roller 46 is detected by the temperature detector 71 of the fixing device 9 based on the output of the thermistor 43a. The CPU 81 acquires the temperature of the fixing roller 46 from the temperature detection unit 71 of the fixing device 9.

  Here, the reason why the CPU 81 uses both the temperature of the fixing device 8 and the temperature of the fixing device 9 as information for determining whether it is in the morning or non-morning state is as follows. This is to solve the problem.

  As described above, in the fixing device replacement system, the fixing devices used as the fixing devices 8 and 9 are replaced and used by the operator according to the type of the recording material P for image formation and the user's preference. There is a case. Therefore, depending on the timing at which the operator carries out the replacement, there is a possibility that the determination as to whether or not the image forming apparatus 100 is in the morning is not properly performed when the power switch 101 is turned on. Below, the detail is demonstrated based on an example of the specific situation assumed.

  A user owns two image forming apparatuses 100 (an image forming apparatus M and an image forming apparatus N), and the fixing device C for envelopes is used as the fixing device 8 in any of the image forming apparatuses M and N. it can. The replacement target is the case of the fixing device 8.

  In the fixing device replacement system, the operator uses different fixing devices depending on the type of recording material P on which an image is formed. Therefore, in the case of a user who owns a plurality of image forming apparatuses 100, depending on the type of recording material P on which an image is formed by each image forming apparatus 100, one fixing device may be replaced between the image forming apparatuses. .

  Assume that the image forming apparatus M enters the standby mode after printing the envelope in a state where the fixing device C for the envelope is mounted as the fixing device 8 of the image forming apparatus M. Here, the fixing device C is controlled by the CPU 81 of the image forming apparatus P so as to maintain, for example, 150 ° C. as the temperature of the standby mode. However, since it is necessary to quickly print thick paper, the operator takes out the envelope fixing device C from the image forming apparatus M, and mounts the cardboard fixing device B as the fixing device 8 of the image forming apparatus M. The taken out fixing device C has a high temperature of about 150 ° C.

  On the other hand, the image forming apparatus N is assumed to remain off after the power switch 101 is turned off several hours ago. In the image forming apparatus N, since the power switch 101 is turned off for a long time, there is a possibility that the charge amount of the toner is lowered and the stability of the image density is lowered. That is, the image forming apparatus N is in the morning state.

  The operator tries to print the envelope in parallel with the printing of the image forming apparatus M after causing the image forming apparatus M to start printing of the urgent cardboard. The operator attaches the fixing device C, which has just been removed from the image forming apparatus M, to the image forming apparatus N as the fixing apparatus 8, and then turns on the power switch 101 of the image forming apparatus N. In this example, in the case of envelope printing, since the fixing process is performed by the tandem fixing route, the operator replaces the fixing device 8 of the image forming apparatus N but does not replace the fixing device 9.

  In such a situation, the power switch 101 is turned on when the temperature of the fixing device C is 50 ° C. or higher, although the image forming apparatus N is in the morning state.

  If the CPU determines whether it is in the morning or non-morning state only at the temperature of the fixing device 8, the temperature of the fixing device C is 50 ° C. (predetermined temperature) or higher, so that the image forming apparatus N is in the morning state. In spite of this, the CPU determines that it is in a non-morning state. As a result, although the image forming apparatus N is in the morning state, the adjustment operation for the morning is not executed, so that there is a possibility that the density of the image is reduced or the density unevenness occurs.

  In the image forming apparatus 100 of this example, as in the above specific example, the fixing device 8 or 9 has a temperature higher than a reference temperature (in this example, 50 ° C.) for determining that the fixing device is in the morning. This solves the problem in the case where the power switch 101 is turned on after being transferred to the fixing device. Since the determination is made based on the temperatures of both the fixing devices 8 and 9, the CPU 81 can determine that the image forming apparatus 100 is in the morning state even in such a case. That is, since the CPU 81 executes the adjustment operation for the morning in such a case, it is possible to suppress the image quality from being deteriorated due to image density reduction or density unevenness.

[Control flow]
A method for determining whether one is in the morning or not in the morning will be described with reference to the flowchart of FIG. FIG. 9 is a flowchart from when the power switch is turned on until the standby mode is entered.

  In this example, when either the temperature of the fixing device 8 or the temperature of the fixing device 9 is equal to or lower than a predetermined temperature (50 ° C. in this example), the CPU 81 determines that the image forming apparatus 100 is in the morning state. When both the temperature of the fixing device 8 and the temperature of the fixing device 9 exceed a predetermined temperature (50 ° C. in this example), the CPU 81 determines that the image forming apparatus 100 is in a non-morning state.

  This flowchart is performed by the CPU 81 functioning as a control unit controlling operations of various mechanisms of the image forming apparatus 100 based on a control program stored in the ROM 83.

  In the following description, the numbers (31) to (40) indicate the numbers shown in the flowchart of FIG.

  When the power switch 101 is turned on by the operator (31), the CPU 81 is activated and starts the flow of FIG.

  The CPU 81 starts the start-up operation of the image forming apparatus 100 (32). As the start-up operation, in addition to either the adjustment operation for the morning or the simple adjustment operation according to the following flows (33) to (38), the temperature of the members of the fixing devices 8 and 9 is adjusted. .

  The CPU 81 determines whether or not the temperature of the fixing device 8 is 50 ° C. or less (33). In this example, the temperature of the fixing device 8 is the temperature of the surface of the fixing roller 40. The temperature of the fixing roller 40 is detected by the temperature detector 89 of the fixing device 8 based on the output of the thermistor 42a. The CPU 81 acquires the temperature of the fixing roller 40 from the temperature detection unit 89 of the fixing device 8 and determines whether it is 50 ° C. or less. When the temperature of the fixing device 8 is 50 ° C. or less, the CPU 81 determines that the image forming apparatus 100 is in the morning state (35). On the other hand, when the temperature of the fixing device 8 is not 50 ° C. or lower (ie, exceeds 50 ° C.), the CPU 81 proceeds to the process (34).

  In (34), the CPU 81 determines whether or not the temperature of the fixing device 9 is 50 ° C. or less. In this example, the temperature of the fixing device 9 is the temperature of the surface of the fixing roller 46. The temperature of the fixing roller 46 is detected by the temperature detector 71 of the fixing device 9 based on the output of the thermistor 43a. The CPU 81 acquires the temperature of the fixing roller 46 from the temperature detection unit 71 of the fixing device 9 and determines whether or not it is 50 ° C. or less. When the temperature of the fixing device 9 is 50 ° C. or lower, the CPU 81 determines that the image forming apparatus 100 is in the morning state (35). That is, the CPU 81 determines that it is in the morning in the morning even when the fixing device 8 is 50 ° C. or higher. On the other hand, if the temperature of the fixing device 9 is not 50 ° C. or lower (ie, exceeds 50 ° C.), the CPU 81 determines that the image forming apparatus 100 is in a non-morning state (37).

  When it is determined that the CPU 81 is in the morning state (35), the CPU 81 causes the morning adjustment operation described above to be executed (36). For example, density adjustment control for adjusting image density is one of the adjustment operations for the morning. Since the details of the adjustment operation for morning use have been described above, the description thereof is omitted here.

  When it is determined that the CPU 81 is in a non-morning state (37), the CPU 81 causes the simple adjustment operation described above to be executed (38). For example, simple density adjustment control for adjusting image density using fewer pattern images than density adjustment control is one simple adjustment operation. Since the details of the simple adjustment operation have been described above, the description thereof is omitted here.

  When the startup operation of the image forming apparatus 100 is completed (39), the CPU 81 shifts to the standby mode (40). Note that when a print reservation is made during the start-up operation, it is possible to shift to execution of a reserved print job instead of the standby mode.

  When at least one of the temperature of the fixing device 8 and the temperature of the fixing device 9 is equal to or lower than a predetermined temperature (50 ° C. in this example) by the flow of (33), (34), (35), (36). Can execute the adjustment operation for the morning, assuming that the state is the morning one. As a result, even if the power switch 101 is turned on while the fixing device having a predetermined temperature or higher is attached to either of the fixing devices 8 and 9 in the image forming apparatus 100 that is originally in the morning, the length of the power switch 101 is increased. It is possible to suppress deterioration in image quality due to time-off.

  Further, due to the flow of (33), (34), (37), (38), both the temperature of the fixing device 8 and the temperature of the fixing device 9 exceed a predetermined temperature (50 ° C. in this example). In this case, the simple adjustment operation can be executed assuming that the non-morning state is present. As a result, when the power switch 101 is turned on immediately after it is turned off, it is not necessary to perform an excessive adjustment operation. An increase in waiting time can be suppressed.

  In this example, when the temperature of the fixing device 8 is 50 ° C. or lower (Yes in (33)), it is determined that the state is in the morning regardless of the temperature of the fixing device 9. However, when the temperature of the fixing device 8 exceeds 50 ° C. (No in (33)), the temperature of the fixing device 9 is determined (34). Therefore, even in the above flow, the CPU 81 controls the content of the adjustment operation based on both the temperature of the fixing device 8 and the temperature of the fixing device 9.

  In this example, the temperature of the fixing device 8 is determined (33) and then the temperature of the fixing device 9 is determined (34). However, the temperature of the fixing device 8 is determined after the temperature of the fixing device 9 is determined. It is good also as composition to do.

(Modification 1)
In the first embodiment described above, the temperature of the fixing device 8 is determined (33) and then the temperature of the fixing device 9 is determined (34) (FIG. 9). The determination of the temperature of the fixing device 8 and the temperature of the fixing device 9 may be performed collectively, instead of sequentially.

  FIG. 10 is a flowchart from when the power switch is turned on until the standby mode is entered. Only differences from the first embodiment will be described. Since other configurations are the same as those of the first embodiment, description thereof is omitted. In the following description, the numbers (51) to (60) indicate the numbers shown in the flowchart of FIG.

  When the power switch 101 is turned on by the operator (51), the CPU 81 is activated and starts the flow of FIG.

  The CPU 81 starts a startup operation of the image forming apparatus 100 (52). As the start-up operation, in addition to the adjustment operation for either morning adjustment or simple adjustment operation according to the following flows (53) to (58), the temperature adjustment of the members of the fixing devices 8 and 9 is executed. .

  The CPU 81 acquires the temperatures of both the fixing device 8 and the fixing device 9 (53). Since the method of acquiring the temperature information is the same as that in the first embodiment, the description thereof is omitted.

  The CPU 81 determines whether or not at least one of the two temperatures acquired in the process (53) is 50 ° C. or less (54). When at least one of the two temperatures acquired in the process of (53) is 50 ° C. or lower, the CPU 81 determines that it is in the morning state (55). The CPU 81 determines that it is in the non-morning state when both of the two temperatures acquired in the process of (53) are 50 ° C. or higher (57).

  The process (56) is the same as (36) in FIG.

  The process (58) is the same as (38) in FIG.

  The processes (59) and (60) are the same as (39) and (40) in FIG. 9, respectively.

  Even in the configuration of this example, the same effect as in the first embodiment can be obtained.

(Modification 2)
In the above description, the temperature of the surface of the fixing roller 40 is used as the temperature of the fixing device 8, and the temperature of the surface of the fixing roller 46 is detected as the temperature of the fixing device 9. The detection method is not limited to this.

  For example, the temperature of the surface of the pressure roller 41 may be detected as the temperature of the fixing device 8, and the temperature of the surface of the pressure roller 47 may be detected as the temperature of the fixing device 9. In this case, the temperature of the pressure roller 41 is detected by the temperature detector 89 of the fixing device 8 based on the output of the thermistor 42b. The CPU 81 acquires the temperature of the pressure roller 41 from the temperature detection unit 89 of the fixing device 8. Further, the temperature of the pressure roller 47 is detected by the temperature detector 71 of the fixing device 9 based on the output of the thermistor 43b. The CPU 81 acquires the temperature of the pressure roller 47 from the temperature detection unit 71 of the fixing device 9.

  Further, for example, the temperature of the frame of the fixing device 8 may be detected as the temperature of the fixing device 8, and the temperature of the frame of the fixing device 9 may be detected as the temperature of the fixing device 9. In this case, a temperature sensor such as a thermistor is provided on the frame of the fixing device 8 and is electrically connected to the temperature detection unit 89 of the fixing device 8. The CPU 81 acquires temperature information based on the output of the thermistor provided in the frame of the fixing device 8 from the temperature detection unit 89 of the fixing device 8. The same applies to the fixing device 9.

  For example, when the fixing device 8 includes an external heating roller that heats the fixing roller 40 from the outer surface of the fixing roller 40, the temperature of the external heating roller is detected as the temperature of the fixing device 8. Also good. The same applies to the fixing device 9.

(Modification 3)
In the above description, the fixing device 8 includes the fixing roller 40 and the pressure roller 41, but other configurations may be used.

  For example, the configuration on the fixing side may be a configuration using a fixing belt that functions as a heating rotator. The fixing belt is an endless belt supported by a plurality of rollers. The fixing belt applies heat to the recording material P while being driven and rotated by a driving roller that is one of the rollers that support the fixing belt. Specifically, the heating roller, which is one of the rollers that support the fixing belt, is a hollow roller, and a halogen heater provided as a heating source therein heats the fixing belt. In the case of the fixing belt, similarly to the fixing roller 40, a thermistor as a sensor for measuring the temperature of the fixing belt is provided. In this case, the temperature of the fixing device 8 or the temperature of the heating roller may be used as the temperature of the fixing device 8.

  For example, the configuration on the pressure side may be a configuration using a pressure belt that functions as a heating rotator. The pressure belt is an endless belt supported by three rollers. The pressure belt applies heat to the recording material P while being rotated by the fixing roller 40. Specifically, a pressure pad for pressing the pressure belt toward the fixing roller 40 is provided on the inner peripheral surface of the pressure belt. A heating roller, which is one of the three rollers, is a hollow roller, and a halogen heater provided as a heating source therein heats the pressure belt. In the case of the pressure belt, similarly to the pressure roller 41, a thermistor as a sensor for measuring the temperature of the pressure belt is provided. In this case, the temperature of the fixing device 8 may be configured to use the temperature of the pressure belt or the heating roller.

  The same applies to the fixing device 9.

8 Fixing Device 9 Fixing Device 42a Thermistor 42b Thermistor 43a Thermistor 43b Thermistor 71 Temperature Detection Unit 78 of Fixing Device 9 Image Forming Unit 81 CPU
89 Temperature detection unit of fixing device 8 100 Image forming apparatus 101 Power switch

Claims (10)

An image forming apparatus for forming an image,
A power switch for starting the image forming apparatus;
An image forming unit for forming a toner image on a recording material;
A first heating unit for heating the toner image formed on the recording material by the image forming unit;
A second heating unit that is provided downstream of the first heating unit in the conveyance direction of the recording material and that heats the toner image on the recording material heated by the first heating unit;
A first temperature detection unit for detecting a temperature of the first heating unit;
A second temperature detection unit for detecting the temperature of the second heating unit;
The power switch based on the first temperature detected by the first temperature detector when the power switch is turned on and the second temperature detected by the second temperature detector when the power switch is turned on. A control unit for controlling the adjustment operation of the image forming unit when the is turned on;
An image forming apparatus comprising:   When at least one of the first temperature and the second temperature is equal to or lower than a predetermined temperature, the control unit causes the image forming unit to perform a first adjustment operation as the adjustment operation, and When the first temperature and the second temperature are higher than a predetermined temperature, the image forming unit is caused to execute a second adjustment operation having fewer adjustment items than the first adjustment operation as the adjustment operation. The image forming apparatus according to claim 1. The image forming unit includes an image carrier that carries a toner image, and a formation unit that forms a toner image on the image carrier,
When at least one of the first temperature and the second temperature is equal to or lower than a predetermined temperature, the control unit sets an image forming condition by the forming unit as one of the first adjustment operations. A pattern image for determination is formed on the image carrier, and when the first temperature and the second temperature are higher than predetermined temperatures, the pattern image is not formed on the forming unit in the second adjustment operation. The image forming apparatus according to claim 2.   The pattern image formed by the forming unit when at least one of the first temperature and the second temperature is equal to or lower than a predetermined temperature includes a plurality of images having different densities. The image forming apparatus according to claim 3. The image forming unit is an image forming unit having an intermediate transfer member and a transfer unit that transfers a toner image carried by the image carrier to the intermediate transfer member,
A receiving unit for receiving input of image data to be formed on the recording material;
A density detector that detects the density of the pattern image on the intermediate transfer member formed by the first adjustment operation, and corrects the image forming conditions based on detection by the density detector And
A conversion unit that converts image data received by the receiving unit after the first adjustment operation into output data based on the image forming conditions corrected by the correction unit as one of the first adjustment operations;
Have
The image forming apparatus according to claim 4, wherein the forming unit forms a toner image corresponding to the output data changed by the conversion unit on the image carrier. The image forming unit includes an image carrier that carries a toner image, and a formation unit that forms a toner image on the image carrier,
The control unit includes a first image including a plurality of images for determining an image forming condition by the forming unit when at least one of the first temperature and the second temperature is equal to or lower than a predetermined temperature. When a pattern image is formed on the image carrier, and the first temperature and the second temperature are higher than a predetermined temperature, the second pattern image having a smaller number of images than the first pattern image is The image forming apparatus according to claim 1, wherein the image forming apparatus is formed in a forming unit. The first heating unit has a first heating rotator for heating the toner image formed on the recording material,
The first temperature detection unit detects the temperature of the first heating rotator,
The second heating unit has a second heating rotator for heating the toner image formed on the recording material,
The image forming apparatus according to claim 1, wherein the second temperature detection unit detects a temperature of the second heating rotator. An informing unit for informing that the image forming apparatus can start an image forming process,
The image forming apparatus according to claim 1, wherein the control unit causes the notification unit to notify the image forming unit after performing the adjustment operation. An image forming apparatus for forming an image,
A power switch for starting the image forming apparatus;
An image forming unit for forming a toner image on a recording material;
A first heating unit for heating the toner image formed on the recording material by the image forming unit;
A second heating unit that is provided downstream of the first heating unit in the conveyance direction of the recording material and that heats the toner image on the recording material heated by the first heating unit;
A first temperature detection unit for detecting a temperature of the first heating unit;
A second temperature detection unit for detecting the temperature of the second heating unit;
The power switch based on the first temperature detected by the first temperature detector when the power switch is turned on and the second temperature detected by the second temperature detector when the power switch is turned on. A control unit that controls whether or not to perform the adjustment operation of the image forming unit when the is turned on,
An image forming apparatus comprising:   The control unit causes the image forming unit to perform the adjustment operation when at least one of the first temperature and the second temperature is equal to or lower than a predetermined temperature, and performs the first temperature and the second temperature. The image forming apparatus according to claim 9, wherein when the second temperature is higher than a predetermined temperature, the image forming unit is not caused to perform the adjustment operation.

Images