JP2016080789A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that prevents extension of a warm-up time even when an environmental temperature is lower than a predetermined temperature by suppressing the quantity of heat required to heat a fixing member to a predetermined printable temperature and the quantity of heat required per unit time during continuous paper feed.SOLUTION: A fixing device includes a fixing member that is heated by a heat source, a pressure member that is arranged opposite to the fixing member, an ambient temperature sensor that detects an environmental temperature, and a control part that reduces the linear velocity of the fixing member when the environmental temperature detected on the basis of an output from the ambient temperature sensor is a first threshold temperature or less and the number of prints of the subsequent print job is a threshold number of sheets or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In recent years, there has been a strong market demand for energy saving and high speed for image forming apparatuses such as printers, copiers, and facsimiles.

  In the image forming apparatus, a developer image is formed on the image carrier by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. This developer image is transferred to a recording medium such as a recording material sheet, printing paper, photosensitive paper, or electrostatic recording medium. The developer image transferred to the recording medium is heated and pressurized by a fixing device and fixed on the recording medium. As the fixing device, a contact heating type fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely adopted.

  Problems in recent years with fixing devices include the following. In other words, the warm-up time, that is, the time required to heat from room temperature to a predetermined temperature that can be printed, and the first print time, that is, the printing operation is performed after receiving the printing request, and the paper discharge is completed. Further shortening of the time to do is desired.

  In addition, there is a problem of so-called temperature drop in which the amount of heat is insufficient at the beginning of continuous printing. This is because the required amount of heat has increased due to an increase in the number of sheets passed per unit time as the speed of the image forming apparatus increases.

  In order to solve such problems, the fixing belt has a configuration in which the fixing belt is directly heated without using the metal thermal conductor, instead of the configuration in which the fixing belt is indirectly heated through the metal thermal conductor. An apparatus has been proposed (for example, Patent Document 1). In this configuration, it is possible to reduce the power consumption by greatly improving the heat transfer efficiency and to further shorten the first print time from the heating standby time. Further, the cost can be reduced due to the absence of the metal heat conductor 102.

  However, in the fixing configuration using the low heat capacity fixing belt as described above, the amount of heat required for printing to a predetermined temperature and the unit for continuous paper passing when the environmental temperature in winter nights or warehouses is lower than normal temperature. The amount of heat required per hour increases. For this reason, there has been a problem that the warm-up time has to be extended in order to store heat in the fixing device when the environmental temperature becomes below a certain level.

In this regard, the fixing unit has a print number detecting unit that detects the number of recording media discharged after image formation, and the fixing condition is changed according to the number of recording medium sheets detected by the print number detecting unit. An apparatus has been proposed (for example, Patent Document 2).
In addition, when the number of image formations is equal to or greater than the predetermined number, the recording material is fed to the nip portion when the temperature of the fixing roller rises to the first temperature. A fixing device that feeds a recording medium to a nip portion at a timing when the temperature rises to a second temperature lower than the temperature of 1 has been proposed (for example, Patent Document 3).

  However, in any technique, when the environmental temperature is lower than a predetermined temperature, for example, room temperature, the amount of heat required to reach a predetermined temperature at which printing can be performed and the amount of heat required per unit time during continuous paper passing increase.

1 is a diagram illustrating a configuration of an image forming apparatus having a fixing device. FIG. 2 is a configuration diagram illustrating an example of a fixing device. 1 is a block diagram illustrating a configuration of an image forming apparatus. It is a figure showing the comparison of the productivity by a prior art and the productivity by this invention. 6 is a flowchart illustrating an operation of the fixing device. 6 is a flowchart illustrating an operation of the fixing device.

  In view of the above problems, the present invention suppresses the amount of heat required up to a predetermined printable temperature and the necessary amount of heat per unit time during continuous paper feeding even when the environmental temperature is lower than the predetermined temperature, thereby extending the warm-up time. It is an object of the present invention to provide a fixing device that can be used.

  In order to solve the above problems, the present invention provides a fixing member that is heated by a heat source, a pressure member that is disposed to face the fixing member, an outside air temperature sensor that detects an environmental temperature, and an output of the outside air temperature sensor. And a controller that slows the linear speed of the fixing member when the environmental temperature detected based on the detected temperature is equal to or lower than the first threshold temperature and the number of printed sheets of the next print job is equal to or lower than the threshold number. provide.

  According to the present invention, even when the environmental temperature is lower than the predetermined temperature, the amount of heat required for the predetermined printable temperature and the necessary amount of heat per unit time during continuous paper feeding are suppressed, and the warm-up time does not need to be extended. A fixing device can be provided.

  Hereinafter, a fixing device and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 1 having a fixing device 20 of the present embodiment. As shown in FIG. 1, the image forming apparatus 1 is a color printer using a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is limited to this system. It is also possible to target not only printers but also copying machines and facsimile machines.

  In FIG. 2, the image forming apparatus 1 has a tandem structure in which photosensitive drums as image carriers capable of forming images as images corresponding to colors separated into yellow, cyan, magenta, and black are arranged in parallel. Is adopted.

  In the image forming apparatus 1, there is a fixing belt that allows a visible image formed on each photoconductive drum 4Y, 4C, 4M, and 4K to move in the direction of the arrow while facing each photoconductive drum 4Y, 4C, 4M, and 4K. A primary transfer process is performed on an intermediate transfer member (hereinafter referred to as a transfer belt) 30 to be used, and each image is superimposed and transferred.

  Thereafter, batch transfer is performed by executing a secondary transfer process on the recording medium P on which a recording sheet or the like is used.

  Around each of the photosensitive drums 4Y, 4C, 4M, and 4K, an apparatus for performing image forming processing according to the rotation of the photosensitive drum 5 is disposed. Now, the photosensitive drum 4K that performs black image formation is targeted. More specifically, a charging device, a developing device, a primary transfer roller 31, and a cleaning device that perform image forming processing along the rotation direction of the photosensitive drum 4K are arranged. For the writing performed after charging, the optical writing device 9 is used.

  The transfer to the transfer belt 30 is performed so that the visible image formed on each photoconductive drum is transferred to the same position on the transfer belt 30 while the transfer belt 30 moves in the direction of the arrow. The timing is shifted from the upstream side in the direction toward the downstream side by the voltage application by the primary transfer roller 31 disposed so as to be opposed to the respective photosensitive drums.

  The image forming apparatus 1 is disposed so as to face four image stations that perform image forming processing for each color and above each of the photosensitive drums 4Y, 4C, 4M, and 4K, and includes a transfer belt 30 and a primary transfer roller 31. A transfer belt unit 3 provided with a secondary transfer roller 36 as a transfer roller that is disposed opposite to the transfer belt 30 and is driven by the transfer belt 30 and rotates along with the transfer belt 30, a driven roller 34, and a transfer roller A cleaning device 35 disposed on the opposite side of the belt 30 for cleaning the transfer belt 30 and an optical writing device 9 serving as an optical writing device disposed on the lower side of the four image stations. ing.

  The optical writing device 9 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygonal mirror as a deflecting means, etc. Corresponding writing light is emitted to form an electrostatic latent image on the photosensitive drum.

  The image forming apparatus 1 is conveyed from the sheet feeding apparatus 10 as a sheet feeding cassette loaded with a recording medium P conveyed between the photosensitive drum 5 and the transfer belt 30, and the sheet feeding apparatus 10. The registration roller pair 12 that feeds the recording medium P that has been fed toward the transfer portion between the photosensitive drums and the transfer belt 30 at a predetermined timing in accordance with the toner image formation timing by the image station, and the recording medium P And a sensor (not shown) for detecting that the front end of the roller has reached the registration roller pair 12.

  The image forming apparatus 1 includes a fixing device 20 as a roller fixing type fixing unit for fixing the toner image to the recording medium P to which the toner image is transferred, and the fixed recording medium P outside the main body of the image forming apparatus 1. And a paper discharge roller 13 for discharging the paper.

  The image forming apparatus 1 includes an outside air temperature sensor S1 that detects an environmental temperature in a place where the image forming apparatus 1 is placed, a fixing device temperature sensor S2 that detects the temperature of the fixing device 20, an outside air temperature sensor S1, and a fixing device temperature. And a control unit 301 for inputting the output of the sensor S2.

  The outside air temperature sensor S1 may be arranged so as to detect the environmental temperature of the fixing device 20.

  The fixing device temperature sensor S2 may be arranged so as to detect the temperature of the casing of the fixing device 20, or may be arranged so as to detect the temperature of the fixing belt 21 provided in the fixing device 20.

  Further, the image forming apparatus 1 includes a paper discharge tray 14 that is disposed on the top of the main body of the image forming apparatus 1 and stacks the recording medium P that is discharged to the outside of the main body of the image forming apparatus 1 by a paper discharge roller 13. 14 and a developer supply unit 2 including toner bottles 2Y, 2C, 2M, and 2K filled with toners of colors of yellow, cyan, magenta, and black.

  In addition to the transfer belt 30 and the primary transfer roller 31, the transfer belt unit 3 includes a driving roller and a driven roller on which the transfer belt 30 is wound.

  The driven roller 34 also has a function as tension urging means for the transfer belt 30. For this reason, the driven roller 34 is provided with urging means using a spring or the like. The transfer belt unit 3, the primary transfer roller 31, the secondary transfer roller 36, and the cleaning device 35 constitute a transfer device.

  The sheet feeding apparatus 10 is disposed in the lower part of the main body of the image forming apparatus 1 and includes a feeding roller 11 as a sheet feeding roller that comes into contact with the upper surface of the uppermost recording medium P. The uppermost recording medium P is fed toward the registration roller pair 12 by being driven to rotate counterclockwise 11.

  Although not shown in detail, the cleaning device 35 provided in the transfer device includes a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 30. The transfer belt 30 is cleaned by scraping and removing foreign matters such as residual toner by a cleaning brush and a cleaning blade.

  The cleaning device 35 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 30.

  FIG. 2 is a configuration diagram showing an example of the fixing device 20 of the present invention. As shown in FIG. 2, the fixing device 20 includes a fixing belt 21 as a rotatable fixing member, a pressure roller 22 as a pressing member rotatably provided facing the fixing belt 21, and a fixing belt. Radiated from the halogen heater 23 as a heat source for heating 21, a nip forming member 24 disposed inside the fixing belt 21, a stay 25 as a support member for supporting the nip forming member 24, and the halogen heater 23. Fixing a reflecting member 26 that reflects light to the fixing belt 21, a temperature sensor 27 as temperature detecting means for detecting the temperature of the fixing belt 21, a separating member 28 that separates paper from the fixing belt 21, and the pressure roller 22. A pressing means (not shown) for pressing the belt 21 is provided.

  The fixing belt 21 is composed of a thin and flexible endless belt member (including a film). Specifically, the fixing belt 21 includes a base material on the inner peripheral side formed of a metal material such as nickel or SUS or a resin material such as polyimide (PI), and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Or it is comprised by the release layer of the outer peripheral side formed with polytetrafluoroethylene (PTFE) etc. Further, an elastic layer formed of a rubber material such as silicone rubber, foamable silicone rubber, or fluorine rubber may be interposed between the base material and the release layer.

  The pressure roller 22 includes a cored bar 22a, an elastic layer 22b made of foamable silicone rubber, silicone rubber, or fluorine rubber provided on the surface of the cored bar 22a, and a PFA provided on the surface of the elastic layer 22b. Alternatively, it is constituted by a release layer 22c made of PTFE or the like. The pressure roller 22 is pressed toward the fixing belt 21 by a pressure unit (not shown) and is in contact with the nip forming member 24 via the fixing belt 21. At the place where the pressure roller 22 and the fixing belt 21 are in pressure contact, the elastic layer 22b of the pressure roller 22 is crushed to form a nip portion N having a predetermined width. The pressure roller 22 is configured to be rotationally driven by a drive unit such as a motor (not shown) provided in the printer body. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing belt 21 at the nip portion N, and the fixing belt 21 is driven to rotate.

  The driving unit may be configured such that the fixing belt 21 is rotated and the pressure roller 22 is rotated following the rotation.

  In the present embodiment, the pressure roller 22 is a solid roller, but may be a hollow roller. In that case, a heating source such as a halogen heater may be disposed inside the pressure roller 22. In addition, when there is no elastic layer, the heat capacity is reduced and the fixability is improved, but when the unfixed toner is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and uneven glossiness is formed on the solid portion of the image. It can happen. In order to prevent this, it is desirable to provide an elastic layer having a thickness of 100 μm or more. By providing an elastic layer having a thickness of 100 μm or more, minute unevenness can be absorbed by elastic deformation of the elastic layer, so that occurrence of uneven gloss can be avoided. The elastic layer 22b may be solid rubber, but if there is no heat source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing belt 21 is less likely to be taken away.

  Both ends of the halogen heater 23 are fixed to a side plate (not shown) of the fixing device 20. The halogen heater 23 is configured to generate heat by being output controlled by a power supply unit provided in the printer body, and the output control is performed based on the detection result of the surface temperature of the fixing belt 21 by the temperature sensor 27. Is called. By such output control of the halogen heater 23, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature. In addition to the halogen heater, an IH, a resistance heating element, a carbon heater, or the like may be used as a heating source for heating the fixing belt 21.

  The nip forming member 24 includes a base pad 241 and a sliding sheet (low friction sheet) 240 provided on the surface of the base pad 241. The base pad 241 is disposed in a longitudinal shape over the axial direction of the fixing belt 21 or the axial direction of the pressure roller 22, and determines the shape of the nip portion N by receiving the pressure applied by the pressure roller 22. is there. The base pad 241 is fixedly supported by the stay 25. Thus, the nip forming member 24 is prevented from being bent by the pressure of the pressure roller 22, and a uniform nip width is obtained in the axial direction of the pressure roller 22. The stay 25 is preferably formed of a metal material having high mechanical strength such as stainless steel or iron in order to satisfy the function of preventing the nip forming member 24 from bending. The base pad 241 is also preferably made of a material that is hard to some extent to ensure strength. As a material for the base pad 241, a resin such as a liquid crystal polymer (LCP), a metal, a ceramic, or the like can be used.

  The base pad 241 is made of a heat resistant member having a heat resistant temperature of 200 ° C. or higher. This prevents the nip forming member 24 from being deformed by heat in the toner fixing temperature range and ensures a stable state of the nip portion N, thereby stabilizing the output image quality. For the base pad 241, general materials such as polyethersulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyethernitrile (PEN), polyamideimide (PAI), polyetheretherketone (PEEK), etc. It is possible to use a heat resistant resin.

  The sliding sheet 240 may be disposed on at least the surface of the base pad 241 that faces the fixing belt 21. As a result, when the fixing belt 21 rotates, the fixing belt 21 slides with respect to the low friction sheet, so that the driving torque generated in the fixing belt 21 is reduced, and the load due to the frictional force on the fixing belt 21 is reduced. The In addition, it is also possible to set it as the structure which does not have a sliding sheet.

  The reflection member 26 is disposed between the stay 25 and the halogen heater 23. In the present embodiment, the reflecting member 26 is fixed to the stay 25. Moreover, since the reflecting member 26 is directly heated by the halogen heater 23, it is desirable that the reflecting member 26 be formed of a high melting point metal material or the like. For example, examples of the material of the reflecting member 26 include aluminum and stainless steel. By arranging the reflection member 26 in this way, the light emitted from the halogen heater 23 toward the stay 25 is reflected to the fixing belt 21. As a result, the amount of light applied to the fixing belt 21 can be increased, and the fixing belt 21 can be efficiently heated. Further, since it is possible to suppress the radiant heat from the halogen heater 23 from being transmitted to the stay 25 and the like, energy saving can be achieved.

  Further, the reflective surface may be formed by subjecting the surface of the stay 25 on the side of the halogen heater 23 to mirror processing such as polishing or painting without providing the reflective member 26 as in the present embodiment. The reflectance of the reflecting surface of the reflecting member 26 or the stay 25 is desirably 90% or more.

  FIG. 3 is a block diagram illustrating a configuration of the image forming apparatus 1. As shown in FIG. 3, the image forming apparatus 1 includes a control unit 301, an image forming unit 302, a transport unit 303, a storage unit 304, an input / output unit 305, a fixing device 20, and an outside air temperature sensor S <b> 1. And a fixing temperature sensor S2.

  The control unit 301 includes an arithmetic device such as a CPU (central processing unit).

  The image forming unit 302 forms an electrostatic latent image on the photosensitive drum 5 that is an electrostatic latent image carrier, and supplies a developer to the electrostatic latent image to form a developer image. The image forming unit 302 further transfers the developer image onto the transfer belt 30 that is a developer image carrier, and transfers the transferred developer image onto the recording medium by the secondary transfer roller 36.

  The conveyance unit 303 conveys the recording medium P one by one.

  The storage unit 304 includes a storage device such as a memory or a nonvolatile memory.

  The input / output unit 305 includes a display input device that inputs and outputs information such as a touch panel.

  The fixing device 20 includes a fixing device control unit 201, a driving unit 202, and a fixing device storage unit 203.

  The fixing device control unit 201 includes an arithmetic device such as a CPU. The fixing device control unit 201 can be omitted by the control unit 301 serving as the operation. Hereinafter, the operation of the fixing device control unit 201 will be described assuming that the control unit 301 also functions.

  The driving unit 202 is controlled by the control unit 301 and rotates the fixing belt 21 at a designated linear speed directly or via the pressure roller 22.

  The control unit 301 can change the linear speed of the fixing belt 21 via the driving unit 202.

  The fixing device storage unit 203 includes a storage device such as a nonvolatile memory. The fixing device storage unit 203 may be configured such that the storage unit 304 also has the function, and the fixing device 20 does not have the fixing device storage unit 203.

  The fixing device storage unit 203 stores a print number storage unit 203A and a linear velocity table 203B. The print number storage unit 203A stores the number of prints of the next print job. The linear speed table 203B stores at least a normal linear speed that is a normal linear speed of the fixing belt 21 and a low-speed linear speed that is a linear speed of the fixing belt 21 that is slower than the normal linear speed.

  As this low linear velocity, an existing predetermined linear velocity can be used, for example, a linear velocity at the time of fixing by passing a thick paper.

  Next, the operation of the fixing device 20 will be described.

  FIG. 4 is a diagram showing a comparison between productivity according to the prior art and productivity according to the present invention. In FIG. 4, the vertical axis indicates the number of discharged recording media C (sheets) discharged by the fixing device 20 and discharged by the image forming apparatus 1, and the horizontal axis indicates the time required to continuously pass through the fixing device 20. A certain paper passing time T (minute) is shown. A graph 401 shows the productivity according to the conventional technique, and a graph 402 shows the productivity according to the embodiment of the present invention.

  In the prior art, as shown in a graph 401, the fixing belt 21 is heated over a period of time T1 (minutes) so that the temperature of the fixing belt 21 becomes a temperature suitable for fixing.

  Thereafter, fixing is performed at a normal linear speed. If the productivity corresponding to the normal linear velocity is Ca (sheets / minute), the number of discharged sheets C in the prior art is expressed by the following equation (1).

  C = Ca (T−T1) (1)

  In the present embodiment, the control unit 301 detects the environmental temperature of the place where the image forming apparatus 1 is placed or the environmental temperature of the fixing device 20, and a constant Ta (which is a threshold value of the environmental temperature and temperature when acquiring print information). C).

  When the ambient temperature that is the environmental temperature is lower than Ta (° C.), the control unit 301 compares the number of prints of the next print job with a constant A (sheets) that is a threshold for the number of prints, and the number of prints is constant A (sheets). If it is less, the linear speed of the fixing belt 21 during paper feeding is made slower than the normal speed, and the fixing operation is started immediately.

  When the outside air temperature is the same as or higher than Ta (° C.), or when the outside air temperature Ta (° C.) is lower and the number of printed sheets is larger than the constant A (sheets), the control unit 301 The fixing speed is changed by changing the line speed to the normal line speed.

  The constant Ta (° C.) is desirably a value lower than the temperature of the standard office environment, for example, around 18 ° C. is desirable. The constant Ta (° C.) is more preferably 17 ° C. or less.

  In addition, the constant A (sheets) is preferably set in the following range in order to prevent the productivity from being lowered by carrying out the present invention.

  If the productivity corresponding to the low linear velocity is Cb (sheets / minute), the number of discharged sheets C in this embodiment is expressed by the following equation (2).

  C = Cb · T (2)

The number of discharged sheets C in which the productivity before the change of the linear velocity is equal to the productivity after the change of the linear velocity is expressed as the following equation (3).
Ca / Cb / T1 / (Ca-Cb) (3)

Therefore, the constant A, which is the threshold number, is preferably within the range of the following equation (4).
A ≦ Ca · Cb · T1 / (Ca-Cb) (4)

  For example, when 60 sheets of Ca, 30 sheets of Cb, and T1 of 30 seconds (0.5 minutes), the threshold number A is desirably 30 sheets or less.

  FIG. 5 is a flowchart showing the operation of the fixing device 20. As shown in FIG. 5, in step 501, the control unit 301 inputs a print request. At this time, the control unit 301 stores the print number of the next job in the print number storage unit 203A.

  In step 502, the control unit 301 determines whether the environmental temperature detected based on the output of the outside air temperature sensor S1 is equal to or lower than the first threshold temperature Ta (° C.). When the control unit 301 determines that the environmental temperature detected based on the output of the outside air temperature sensor S1 is equal to or lower than the first threshold temperature Ta (° C.), the control unit 301 proceeds to step 503 and proceeds to the first threshold temperature Ta (° C.). If it is determined that it is not below, the process proceeds to step 505.

  In step 503, the control unit 301 determines whether the print number of the next job read from the print number storage unit 203A is equal to or less than the threshold number A (sheets). If the control unit 301 determines that the number of printed sheets of the next job is equal to or less than the threshold number A (sheets), the control unit 301 proceeds to step 504.

  In step 504, the control unit 301 reads the low speed linear velocity from the linear velocity table 203B, and makes the linear velocity of the fixing belt 21 slower than the normal linear velocity based on the low velocity linear velocity.

  In step 505, the control unit 301 reads the normal linear velocity from the linear velocity table 203B, and sets the linear velocity of the fixing belt 21 to the normal linear velocity based on the normal linear velocity.

  In step 506, the control unit 301 executes image formation.

  As described above, in the fixing device 20 of the present embodiment, the environmental temperature detected based on the output of the outside air temperature sensor S1 is equal to or lower than the first threshold temperature Ta (° C.), and the number of prints of the next job is Is determined to be equal to or less than the threshold number A (sheets), the low speed linear velocity is read from the linear velocity table 203B, and the linear velocity of the fixing belt 21 is made slower than the normal linear velocity based on the low linear velocity.

  When the linear velocity is decreased, the amount of heat supplied by the fixing belt 21 per unit area increases. Therefore, the heat storage operation that is conventionally required at a constant temperature becomes unnecessary.

  Therefore, in the embodiment of the present invention as compared with the prior art, since the sheet passing to the fixing device 20 can be started immediately after receiving the print request, the conventional technique is used when printing a small number of sheets such as printing only one sheet. There is an effect that productivity is superior to control.

(Second Embodiment)
The configuration of the image forming apparatus 1 and the configuration of the fixing device 20 in the present embodiment are the same as the configuration of the image forming apparatus 1 and the configuration of the fixing device 20 in the first embodiment, respectively.

  Next, the operation of the fixing device 20 will be described.

  FIG. 6 is a flowchart showing the operation of the fixing device 20. As shown in FIG. 6, in step 601, the control unit 301 inputs a print request. At this time, the control unit 301 stores the print number of the next job in the print number storage unit 203A.

  In step 602, the control unit 301 determines whether the temperature of the fixing device 20 to the fixing belt 21 detected by the fixing device temperature sensor S2 is equal to or lower than the second threshold temperature Tf (° C.).

  The second threshold temperature Tf (° C.) is preferably the temperature of the fixing device 20 to the fixing belt 21 suitable for fixing at the normal linear speed. More preferably, the second threshold temperature Tf (° C.) is 100 ° C. or lower. The second threshold temperature Tf (° C.) is most desirably 30 ° C. or higher and 100 ° C. or lower.

  When the control unit 301 determines that the temperature of the fixing device 20 to the fixing belt 21 detected by the fixing device temperature sensor S2 is equal to or lower than the second threshold temperature Tf (° C.), the control unit 301 proceeds to step 603 and proceeds to the second threshold temperature. If it is determined that the temperature is not less than Tf (° C.), the process proceeds to step 606.

  In step 603, the control unit 301 determines whether the environmental temperature detected based on the output of the outside air temperature sensor S1 is equal to or lower than the first threshold temperature Ta (° C.). When the control unit 301 determines that the environmental temperature detected based on the output of the outside air temperature sensor S1 is equal to or lower than the first threshold temperature Ta (° C.), the control unit 301 proceeds to step 604 and proceeds to the first threshold temperature Ta (° C.). If it is determined that it is not below, the process proceeds to step 606.

  In step 604, the control unit 301 determines whether the print number of the next job read from the print number storage unit 203A is equal to or less than the threshold number A (sheets). If the control unit 301 determines that the number of printed sheets of the next job is equal to or less than the threshold number A (sheets), the control unit 301 proceeds to step 605. If the control unit 301 determines that it is not equal to or less than the threshold number A (sheets), the process proceeds to step 606.

  In step 605, the control unit 301 reads the low speed linear velocity from the linear velocity table 203B, and makes the linear velocity of the fixing belt 21 slower than the normal linear velocity based on the low linear velocity.

  In step 606, the control unit 301 reads the normal linear velocity from the linear velocity table 203B, and sets the linear velocity of the fixing belt 21 to the normal linear velocity based on the normal linear velocity.

  In step 607, the control unit 301 performs image formation.

  As described above, in the fixing device 20 of the present embodiment, the temperature of the fixing device 20 to the fixing belt 21 detected by the fixing device temperature sensor S2 is equal to or lower than the second threshold temperature Tf (° C.) and the outside air temperature. When it is determined that the environmental temperature detected based on the output of the sensor S1 is equal to or lower than the first threshold temperature Ta (° C.) and the number of printed sheets of the next job is equal to or lower than the threshold number A (sheets), the linear velocity The low speed linear velocity is read from the table 203B, and the linear velocity of the fixing belt 21 is made slower than the normal linear velocity based on the low linear velocity.

  Therefore, in the embodiment of the present invention as compared with the prior art, since the sheet passing to the fixing device 20 can be started immediately after receiving the print request, the conventional technique is used when printing a small number of sheets such as printing only one sheet. There is an effect that productivity is further superior to control.

1: Image forming devices 4Y, 4M, 4C, 4K: Photoconductor drum 20: Fixing device 21: Fixing belt 22: Pressure roller 23: Halogen heater 30: Transfer belt 31: Primary transfer roller 36: Secondary transfer roller 203 : Fixing device storage unit 203B: Linear speed table 301: Control unit S1: Outside air temperature sensor S2: Fixing device temperature sensor

JP2013-137470A JP2013-231803A JP 2006-010753 A

Claims (7)

A fixing member heated by a heat source;
A pressure member disposed to face the fixing member;
An outside air temperature sensor that detects the environmental temperature,
When the environmental temperature detected based on the output of the outside air temperature sensor is equal to or lower than the first threshold temperature and the number of printed sheets of the next print job is equal to or smaller than the threshold number, the linear velocity of the fixing member is set to a normal line. A control unit that changes to a lower linear speed that is slower than the normal linear speed, which is a high speed;
A fixing device. A fixing device temperature sensor for detecting the temperature of the fixing device;
The controller is
The environmental temperature detected based on the output of the outside air temperature sensor is not more than a first threshold temperature, and the temperature of the fixing device detected based on the output of the fixing device temperature sensor is not more than a second threshold temperature, The fixing device according to claim 1, wherein when the number of printed sheets of the next print job is equal to or less than a threshold number, the linear speed of the fixing member is changed from the normal linear speed to the low-speed linear speed.   The fixing device according to claim 1, wherein the first threshold temperature is 17 ° C. or lower.   The fixing device according to claim 2, wherein the second threshold temperature is 100 ° C. or lower. The threshold number A is
Productivity of Ca corresponding to the normal linear speed (sheets / minute),
Cb, productivity (sheets / minute) corresponding to the low linear velocity,
When T1 is the time (minutes) required for heating the fixing member at the normal linear speed,
The following formula A ≦ Ca · Cb · T1 / (Ca-Cb)
The fixing device according to any one of claims 1 to 4, defined by: The low linear velocity is
The fixing device according to claim 1, wherein the fixing speed is a linear speed at the time of fixing the thick paper. An image forming apparatus comprising the fixing device according to claim 1.

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