JP6083963B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a fixing device that heats and melts toner to fix it on a recording material.

  Conventionally, in an image forming apparatus using an electrophotographic process, a toner image (unfixed image) based on an image signal from a personal computer or the like is electrostatically carried on a recording material. A system is known in which the toner image is fixed on a recording material by heating and pressurizing this in a fixing device.

  Here, as the fixing device, in order to realize energy saving and quick start, a film heating type device has been put into practical use. A film heating type fixing device has been proposed in, for example, Japanese Patent Application Laid-Open No. H10-228707.

  That is, a fixing nip portion is formed by sandwiching a heat-resistant fixing film between a ceramic heater as a heating body and a pressure roller as a pressure member. Then, a recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced between the fixing film and the pressure roller in the fixing nip portion, and is nipped and conveyed together with the fixing film. Thus, the unfixed toner image is fixed to the recording material surface by heat and pressure by heating and pressurizing at the fixing nip portion.

  In the film heating type fixing device, the recording material may be clogged due to condensation slip. That is, in the film heating type fixing device, the recording material is nipped and conveyed by receiving a driving force by a frictional force from the pressure roller. The fixing film rotates by a frictional force received from the recording material while receiving a sliding frictional resistance from the ceramic heater and the support member.

  Accordingly, the recording material is conveyed by receiving a driving force from the pressure roller and a drag force from the fixing film. In this conveyance process, the recording material receives heat from the ceramic heater through the fixing film, thereby fixing the toner on the recording material as a permanent image.

  In this process, water vapor generated when the recording material is heated adheres to the surface of the pressure roller, causing condensation. The frictional force decreases due to the presence of moisture between the pressure roller and the recording material, and condensation slip occurs due to insufficient frictional force for conveying the recording material. When condensation slip occurs, the conveyance speed at the fixing nip portion is slower than the conveyance speed at the image forming portion. For this reason, the recording material is not conveyed by the pressure roller, and there is a high possibility that the recording material is clogged.

  In order to solve these problems, Patent Document 2 discloses that a fixing fan is provided on the pressure roller side of the fixing device to drive it, thereby discharging water vapor to the outside of the fixing device. Techniques for preventing internal condensation are disclosed.

JP-A-4-204980 JP 2002-365946 A

  In Patent Document 2, a blower fan is driven as a countermeasure against condensation slip. On the other hand, there is a case where the fixing film or the pressure roller constituting the fixing member provided in the fixing device is excessively cooled by driving the blower fan. In this case, since the temperature of the fixing member becomes lower than a desired temperature, the toner cannot be sufficiently melted, resulting in poor fixing. As a result, the toner is peeled off from the recording material to cause an image defect, or the peeled toner adheres to the fixing member and causes a recording material conveyance failure.

  As a countermeasure against the above-mentioned fixing failure, it is possible to heat the fixing member for a long time while the blower fan is driven. However, in this case, it takes time until the recording material is discharged out of the apparatus. As a result, the FPOT (First Print Out Time) indicating the time required from when the print start button is pressed until the first recording material is discharged is lowered. Further, PPM (Page Per Minute) indicating the print discharge amount per minute of the image forming apparatus is lowered. As a result, the production performance of the image forming apparatus is reduced.

The present invention solves the above-described problems, and an object of the present invention is to optimize the blowing amount to the fixing unit for each recording material based on the basis weight information or smoothness information of the recording material. As a result, an image forming apparatus that suppresses condensation slip and secures fixability without degrading the performance of FPOT, PPM, or the like is provided.

A typical configuration of the image forming apparatus according to the present invention for achieving the object includes an image forming unit that forms a toner image on a recording material, a heating rotator, and a roller that forms a nip portion together with the heating rotator. If, anda fixing unit that fixes the toner image on the recording material by heating pressurized while conveying the recording material on which the toner image is formed by the nip portion has a blower fan, toward the roller In an image forming apparatus having a blowing unit that blows air, a control unit that controls electric power supplied to the blowing fan, and a basis weight detection unit that detects the basis weight of the recording material, by a virtual surface including the nip portion, When divided into two regions, a region on the side where the heating rotator is present and a region on the side where the roller is present, the air blowing port of the air blowing unit is provided in a region on the side where the roller is present, The control unit is used for recording materials with a small basis weight. It characterized in that it is controlled so that the power supplied to the blower fan becomes larger than when carrying the large recording material having a basis weight in the nip portion when being conveyed by the nip portion.

According to the above configuration, optimizing the air volume by the air supply unit for each recording material according to the basis weight information of the recording material. As a result, it is possible to suppress condensation slip and to ensure the fixability without degrading the performance of FPOT or PPM.

1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. The fixing film side provided on the fixing portion is a cross-sectional view showing a structure in which a blower unit. FIG. 6 is a cross-sectional explanatory diagram illustrating a configuration in which a blowing unit is provided on the pressure roller side provided in the fixing unit . FIG. 3 is a perspective explanatory view illustrating a configuration of a fixing unit . (A) is a longitudinal sectional view illustrating the configuration of a ceramic heater provided in the fixing unit , (b) is a back view illustrating the configuration of the ceramic heater provided in the fixing unit , and (c) is a diagram of the ceramic heater provided in the fixing unit . It is a cross-sectional explanatory drawing which shows a structure. And the basis weight W of the recording material in the first embodiment of the image forming apparatus according to the present invention, the relationship between the input voltage V to the blower shown. (A) a basis weight W is less than 70 g / ^{m 2} of the recording material, the input voltage V to the blower unit is driven as 24V, at a basis weight W of the recording material is 70 g / ^{m 2} or more, the input to the blower An example in which the voltage V is stopped at 0V is shown. (B) a basis weight W is less than 60 g / ^{m 2} of the recording material, to drive the input voltage V to the blower as 24V. The basis weight W up to ^60g / ^{m 2 ~80g} / m 2 of the recording material, linearly decreases the input voltage V to the blower to 0V from 24V. Then, at a basis weight W of the recording material is 80 g / m ² or more, an example of stopping the input voltage V to the blower unit was maintained at 0V. (A) is a front view which shows an example of a user setting means. (B) is a diagram showing the relationship between various recording materials and basis weight W. FIG. It is a figure which shows the ventilation operation | movement by the ventilation part in 1st Embodiment. (A) shows a state in which the basis weight W of the recording material is stopped input voltage V to the blower as 0V in the case of 70 g / m ² or more. (B) shows a state in which the basis weight W of the recording material is an input voltage V to the blower unit is driven as 24V less than 70 g / ^{m 2.} It is a figure explaining the generation | occurrence | production rate of the condensation slip and fixing failure in 1st Embodiment. It is a figure which shows the relationship between the various recording materials and Beck smoothness S in 2nd Embodiment of the image forming apparatus which concerns on this invention. It is a figure which shows the ventilation operation | movement by the ventilation part in 2nd Embodiment. (A) In the Bekk smoothness S is less than Bekk smoothness 10sec of the recording material, the input voltage V to the blower is stopped as 0V, Bekk smoothness S of the recording material Bekk smoothness 10sec or more, the blowing unit A state in which the input voltage V is driven at 24V is shown. (B) the Bekk smoothness S of the recording material is less than Bekk smoothness 10 sec, to stop the input voltage V to the blower as 0V. The Bekk smoothness S until Bekk smoothness 10sec~30sec the recording material is linearly driving by increasing the input voltage V to the blower from 0V to 24V. Then, the Bekk smoothness 30sec or more, showing a state in which by driving keeping an input voltage V to the blowing section to 24V. It is a figure explaining the generation | occurrence | production rate of the condensation slip and fixing failure in 2nd Embodiment. It is a figure which shows the relationship between the various recording materials, basic weight W, and Beck smoothness S in 3rd Embodiment of the image forming apparatus which concerns on this invention. In 3rd Embodiment, the basic weight W of a recording material is taken on a vertical axis | shaft, and the figure which shows area | region ZA-ZD divided | segmented for every risk level which a condensation slip generate | occur | produces on the coordinate when taking Beck smoothness S on a horizontal axis. It is. It is a figure which shows the ventilation operation | movement by the ventilation part in 3rd Embodiment. The state where the input voltage V to the air blowing unit is changed stepwise to 24V, 12V, 4V, and 0V for each region ZA to ZD divided for each risk level in which condensation slip occurs is shown in FIG. It is a figure explaining the generation | occurrence | production rate of the condensation slip and fixing failure in 3rd Embodiment. It is sectional explanatory drawing explaining the structure of a basic weight detection means. It is a block diagram of the control system explaining the basis weight detection method of the recording material by a basis weight detection means. It is a figure explaining the relationship between the basic weight of a recording material, and a calculation output.

  An embodiment of an image forming apparatus according to the present invention will be specifically described with reference to the drawings.

  First, the configuration of the first embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. 1 to 10 and FIGS. 17 to 19.

In the present embodiment, the blower fan 330 serving as the blower unit is driven based on the basis weight information that is the basis weight information including the weight information per unit area of the recording material 1. The blower fan 330 blows air to the fixing device 300 serving as a fixing unit that melts and fixes the toner image formed on the recording material 1 (on the recording material).

<Image forming apparatus>
First, the configuration of the image forming apparatus according to the present invention will be described together with the image forming operation with reference to FIG. FIG. 1 shows an example of an image forming unit 2 of a color image forming apparatus. Operation control of the image forming apparatus 13 body (image forming apparatus main body) is a CPU as a control unit; performed by (Central Processing Unit) 200, and the storage means and comprising memory 250.

  The operation panel 210 serving as user setting means shown in FIG. 7A will be described later.

  In the image forming unit 2, the surfaces of the photosensitive drums 22Y, 22M, 22C, and 22K as image carriers are uniformly charged by charging devices 23Y, 23M, 23C, and 23K as charging means. Then, electrostatic latent images are formed on the surfaces of the photosensitive drums 22Y, 22M, 22C, and 22K by exposure light that is turned on by the scanner units 24Y, 24M, 24C, and 24K as exposure means based on the exposure time converted by an image processing unit (not shown). Form.

  Each color toner is supplied to the electrostatic latent images formed on the surfaces of the photosensitive drums 22Y, 22M, 22C, and 22K by the developing devices 26Y, 26M, 26C, and 26K serving as developing means, and developed. Form.

  Further, primary transfer rollers 27Y, 27M, 27C, and 27K serving as primary transfer means provided opposite to the photosensitive drums 22 via the intermediate transfer belt 28 are provided. Then, by the action of the primary transfer roller 27, the single color toner images formed on the surface of the respective photosensitive drums 22 are sequentially superimposed and transferred onto the intermediate transfer belt 28 to form a multicolor toner image.

  On the other hand, the recording material 1 placed on the feeding cassette 21a and the feeding tray 21b provided in the feeding unit 21 is appropriately conveyed by the feeding rollers 20a and 20b. The pre-registration sensor 17 detects the passage of the leading edge of the recording material 1. Then, the recording material 1 is conveyed to the nip portion between the intermediate transfer belt 28 and the secondary transfer roller 29 in synchronization so that the tip position of the toner image formed on the intermediate transfer belt 28 by the registration roller 16 coincides. Is done.

  Then, the multicolor toner image transferred onto the intermediate transfer belt 28 is transferred to the recording material 1 by the action of the secondary transfer roller 29 serving as a secondary transfer means. Then, the recording material 1 on which the unfixed multicolor toner image is transferred is conveyed to a fixing nip portion 14 between a fixing film 320 serving as a heating rotator of the fixing device 300 and a pressure roller 322 serving as a pressure rotator. . Then, the unfixed toner image is heated and melted and pressed to permanently fix the toner image on the recording material 1. The recording material 1 on which the toner image is fixed by the fixing device 300 is discharged out of the apparatus by the discharge roller 61 and placed on a discharge tray (not shown). The toner remaining on the intermediate transfer belt 28 is cleaned by the cleaning device 40.

  The toner cartridges 25Y, 25M, 25C, and 25K replenish toner of each color to the developing devices 26Y, 26M, 26C, and 26K. A series of these image forming process operations are controlled by the CPU 200.

  For convenience of explanation, the photosensitive drums 22Y, 22M, 22C, and 22K provided for each station of each color of yellow Y, magenta M, cyan C, and black K will be described as a representative. The same applies to other image forming process means.

  The photosensitive drum 22 is configured by applying an organic optical transmission layer to the outer periphery of an aluminum cylinder, and rotates in the counterclockwise direction of FIG. 1 in response to an image forming operation when a driving force of a driving motor (not shown) is transmitted.

  As charging means, four charging devices 23 for charging the surface of the photosensitive drum 22 of yellow Y, magenta M, cyan C, and black K are provided for each color station. Each charging device 23 includes charging sleeves 23aY, 23aM, 23aC, and 23aK.

  Exposure light to the photosensitive drum 22 is sent from the scanner unit 24, and an electrostatic latent image is formed on the surface of the photosensitive drum 22 by selectively exposing the surface of the photosensitive drum 22.

  As a developing means, the electrostatic latent image formed on the surface of the photosensitive drum 22 is visualized. For this purpose, four developing devices 26 for developing yellow Y toner, magenta M toner, cyan C toner, and black K toner are provided for each color station. Each developing device 26 is provided with developing sleeves 26aY, 26aM, 26aC, and 26aK.

  In this embodiment, toner having a negative charge property is used. Further, a developing bias is applied between each developing sleeve 26a and each corresponding photosensitive drum 22 from a power source (not shown). Each developing device 26 is detachably attached to the main body of the image forming apparatus 13.

  The intermediate transfer belt 28 is in contact with each photosensitive drum 22, and rotates in accordance with the rotation of the photosensitive drum 22 in the clockwise direction of FIG. 1 when forming a color image, so that the monochromatic toner formed on the surface of each photosensitive drum 22 is formed. An image is transferred onto the outer peripheral surface of the intermediate transfer belt. Further, a primary transfer bias is applied between each primary transfer roller 27 and each corresponding photosensitive drum 22 from a power source (not shown).

  A feeding unit 21 serving as a feeding unit is provided with a feeding cassette 21a in which the recording material 1 is accommodated and a feeding tray 21b. The recording material 1 is conveyed by feeding rollers 20a and 20b, and reaches the registration roller 16. The leading edge of the recording material 1 is detected by the pre-registration sensor 17, and the recording material 1 stops for a predetermined time with the leading edge of the recording material 1 protruding to the downstream side of the registration roller 16.

While the recording material 1 is stopped, as shown in FIGS. 17 and 18, an ultrasonic transmission unit 18a and an ultrasonic reception unit 18b are provided so as to sandwich the conveyance path of the recording material 1. The basis weight of the recording material 1 can be detected by the basis weight detector 18 as a weight detector. The basis weight of the recording material 1 referred to here is the mass per unit area of the recording material 1, and the mass per square meter is represented by (g / m ² ).

  At the time of image formation, the recording material 1 is conveyed to the secondary transfer roller 29 by the registration roller 16 in accordance with the timing at which the multicolor toner image on the intermediate transfer belt 28 reaches the secondary transfer roller 29.

  The secondary transfer roller 29 comes into contact with the intermediate transfer belt 28 to nipping and conveying the recording material 1, transfers the multicolor toner image on the intermediate transfer belt 28 to the recording material 1, and conveys it to the fixing device 300. The secondary transfer roller 29 is pressed against the recording material 1 at the position indicated by the solid line in FIG. 1 while the multicolor toner image is being transferred onto the recording material 1, and is indicated by the broken line in FIG. 1 after the printing process. Separated into position. A secondary transfer bias is applied between the secondary transfer roller 29 and the intermediate transfer belt 28 from a power source (not shown).

  The fixing device 300 heats and melts and fixes the multicolor toner image transferred onto the recording material 1 while conveying the recording material 1.

  The discharge roller 61 discharges the recording material 1 to a discharge tray (not shown), and the image forming unit 2 ends a series of image forming operations.

  In this embodiment, the recording material 1 is conveyed at a conveyance speed of 190 mm / sec.

<Fixing device>
Next, the configuration of the fixing device 300 of this embodiment will be described in detail with reference to FIGS.

FIG. 2 shows an example in which a blower fan 330 is provided outside the device frame 324 on the fixing film 320 side provided in the fixing device 300. FIG. 3 shows an example in which a blower fan 330 is provided outside the device frame 324 on the pressure roller 322 side provided in the fixing device 300. A blower port 340 and an exhaust port 341 are provided in the device frame 324 corresponding to each blower fan 330. In this embodiment, an example in which the blower fan 330 is provided outside the device frame 324 is shown, but the blower fan 330 may be provided inside the device frame 324. Further, as the air blowing section that blows air to the fixing device 300, a suction fan may be provided outside or inside the device frame 324.

  As shown in FIGS. 2 and 3, the fixing device 300 of the present embodiment is a tensionless type heating device that is heated by a fixing film 320 that is a heating rotator and is pressed by a pressure roller 322 that is a pressure rotator. It is configured as.

  The fixing film 320 is a cylindrical (endless belt-like) member in which an elastic layer is provided on a film-like member. Inside the fixing film 320, a heater holder 317 having a substantially semicircular arc-shaped cross section serving as a heating body holding member for rotatably holding the fixing film 320 and having heat resistance and rigidity is disposed. The fixing film 320 is loosely fitted on the heater holder 317.

  A heater 316 made of a long ceramic heater or the like serving as a heating body (heat source) is disposed along the longitudinal direction of the heater holder 317 so as to face the pressure roller 322 of the heater holder 317.

  The heater holder 317 is formed of a liquid crystal polymer resin having high heat resistance and plays a role of holding the heater 316 and guiding the fixing film 320. In the present embodiment, Zenite 7755 (trade name) manufactured by DuPont was used as the liquid crystal polymer. The maximum usable temperature of Zenite 7755 is about 270 ° C.

  The pressure roller 322 forms a silicone rubber layer with a thickness of about 3 mm on a stainless steel core by injection molding, and covers a PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) resin tube with a thickness of about 40 μm thereon. Do it. The pressure roller 322 is rotatably held at both ends of the core metal by bearings provided on side plates (not shown) on the back side and the near side of the device frame 324 of the fixing device 300 in FIGS.

  A fixing film unit 3 including a heater 316, a heater holder 317, a fixing film 320, and the like is disposed facing the pressure roller 322, and the heater 316 side is disposed in parallel with the pressure roller 322 at a position facing the pressure roller 322. ing.

  Both ends of the heater holder 317 are urged toward the pressure roller 322 with a force of 98 N (10 kgf) on one side and a total pressure of 196 N (20 kgf) by a pressure mechanism (not shown). Thus, the heater 316 is pressed against the elastic layer of the pressure roller 322 via the fixing film 320 with a predetermined pressing force against the elasticity of the elastic layer. As a result, a fixing nip portion 14 having a predetermined width necessary for heat fixing is formed. A pressurizing mechanism (not shown) has a pressure releasing mechanism, and is configured such that when the recording material 1 is jammed, the pressure is released and the recording material 1 can be easily removed.

  The heater holder 317 is provided with a thermistor 318 that elastically contacts the inner surface of the fixing film 320 above the heater holder 317 via a stainless arm 325 made of an elastic member and detects the temperature of the inner surface of the fixing film 320. Yes. A thermistor 319 for detecting the temperature of the heater 316 is provided on the upper surface of the heater 316.

  The thermistor 318 is attached to the inner peripheral surface of the fixing film 320 even when the movement of the inner peripheral surface of the fixing film 320 becomes unstable due to the elastic swing of the arm 325 fixedly supported by the heater holder 317. Always in contact.

  FIG. 4 shows the positional relationship between the heater 316 and the thermistors 318 and 319 in the fixing device 300 of the present embodiment. The thermistor 318 is disposed near the center in the longitudinal direction of the fixing film 320. The thermistor 319 is disposed near the end of the heater 316 in the longitudinal direction. The thermistor 318 is disposed so as to contact the inner peripheral surface of the fixing film 320, and the thermistor 319 is disposed so as to contact the upper surface of the heater 316.

  The thermistors 318 and 319 are connected to the CPU 200. The CPU 200 controls the heater driving circuit 328 based on the output signals of the thermistors 318 and 319 to control the energization of the heater 316 and adjust the temperature of the fixing film 320.

  The pressure roller 322 is rotationally driven in a counterclockwise direction at a predetermined peripheral speed as indicated by arrows in FIGS. 2 and 3 by a driving means such as a motor (not shown).

  A rotational force acts on the cylindrical fixing film 320 by the pressure frictional force in the fixing nip portion 14 between the outer peripheral surface of the pressure roller 322 and the outer peripheral surface of the fixing film 320 by the rotational driving of the pressure roller 322. Then, while the inner peripheral surface of the fixing film 320 is in close contact with the lower surface of the heater 316 and slides, the outer periphery of the heater holder 317 is driven to rotate in the clockwise direction as indicated by arrows in FIGS.

  The inner peripheral surface of the fixing film 320 is coated with grease as a lubricant to ensure slidability between the semicircular outer peripheral surface of the heater holder 317 and the inner peripheral surface of the fixing film 320. Yes.

  The pressure roller 322 is rotationally driven, and the cylindrical fixing film 320 is rotated in accordance with the rotation. Then, the heater 316 is energized. The heater 316 is heated to a predetermined temperature, and the temperature is adjusted. In this state, the recording material 1 carrying the unfixed toner image is guided and conveyed along the entrance guide 323 in the fixing nip portion 14 between the fixing film 320 and the pressure roller 322. Then, the toner image carrying surface side of the recording material 1 is in close contact with the outer peripheral surface of the fixing film 320 at the fixing nip portion 14, and the fixing nip portion 14 is nipped and conveyed together with the fixing film 320.

  In this nipping and conveying process, the heat of the heater 316 is applied to the recording material 1 through the fixing film 320, and the unfixed toner image on the recording material 1 is heated and pressed by the recording material 1 and melted and fixed. The recording material 1 that has passed through the fixing nip 14 is separated from the fixing film 320 by the curvature, and is discharged to the outside by the discharge roller 61.

<Heater>
Next, the heater 316 will be described with reference to FIG. FIG. 5A is a longitudinal cross-sectional explanatory view showing an example of a ceramic heater, FIG. 5B is a back side explanatory view, and FIG. 5C is a transverse cross-sectional explanatory view.

  In this embodiment, the heater 316 as a heat source applies a conductive paste containing an alloy of silver and palladium on an alumina substrate in a film shape with a uniform thickness by a screen printing method. Furthermore, a ceramic heater is used in which a resistance heating element is formed and a glass coat is applied with pressure-resistant glass.

  The heater 316 has an alumina substrate 5 whose longitudinal direction is a direction orthogonal to the conveyance direction of the recording material 1. Furthermore, it is coated on the surface side of the alumina substrate 5 in the form of a line or a band by screen printing along the longitudinal direction. And it has the resistance heating element layer 6 with a thickness of about 10 μm and a width of about 1 mm to 5 mm of a conductive paste containing an alloy of silver (Ag) and palladium (Pd) that generates heat when current flows.

  Further, as the power supply pattern for the resistance heating element layer 6, there are similarly provided electrode portions 7, 8 and extended circuit portions 9, 10 patterned on the surface side of the alumina substrate 5 by screen printing of silver paste. Furthermore, in order to ensure the protection and insulation of the resistance heating element layer 6 and the extension circuit portions 9 and 10, a thin film having a thickness of about 10 μm capable of withstanding the rubbing with the fixing film 320 formed thereon. It has a glass coat 11. Furthermore, it has a thermistor 319 provided on the back surface side of the alumina substrate 5.

  As shown in FIGS. 2 and 3, the heater 316 is supported by being fixed to the heater holder 317 by exposing the side on which the glass coat 11 is provided from the heater holder 317.

  A power feeding connector 331 is attached to the electrode portions 7 and 8 side of the heater 316. Power is supplied from the heater drive circuit unit 328 to the electrode units 7 and 8 through the power supply connector 331, so that the resistance heating element layer 6 generates heat and the heater 316 quickly rises in temperature. The heater drive circuit unit 328 is controlled by the CPU 200.

  In normal use, the rotation of the fixing film 320 starts with the rotation of the pressure roller 322, and the temperature of the inner peripheral surface of the fixing film 320 increases with the temperature of the heater 316. Energization of the heater 316 is controlled by PID (P: Proportional (proportional), I: Integral (integral), D: Derivative)) control. In the PID control, the input value is controlled by three elements, ie, the deviation between the output value and the target value, its integration, and differentiation. Then, the input power is controlled so that the inner peripheral surface temperature of the fixing film 320, that is, the detected temperature of the thermistor 318 becomes 190 ° C.

<Fixing film>
Next, the fixing film 320 will be described. In the present embodiment, the fixing film 320 is a cylindrical (endless belt-like) member in which an elastic layer is provided on a film-like member. Specifically, a silicone rubber layer, which is an elastic layer having a thickness of about 300 μm, is formed on a cylindrical film having a thickness of 30 μm using stainless steel (SUS) as a material. Further, a PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer) resin tube having a thickness of 30 μm is coated thereon as the outermost surface layer.

  A blower fan 330 shown in FIGS. 2 and 3 discharges water vapor discharged from the recording material 1 to the outside of the fixing device 300. Air blown by the blower fan 330 enters the fixing device 300 through the air blowing port 340 provided in the device frame 324 and is exhausted out of the fixing device 300 through the exhaust port 341.

  In FIG. 2, the air is blown from the fixing film 320 side to the vicinity of the fixing nip portion 14. In FIG. 3, the air is blown from the pressure roller 322 side to the vicinity of the fixing nip portion 14.

  The external dimensions of the blower fan 330 are a vertical dimension of 60 mm, a horizontal dimension of 60 mm, and a thickness of 10 mm. Further, a voltage in the range of 0V to 24V from a DC (direct current) 24V power source (not shown) in the main body of the image forming apparatus 13 is supplied to the blower fan 330 by PWM (Pulse Width Modulation) control by the CPU 200. Thereby, the air volume of the blower fan 330 is adjusted.

  Here, the blower fan 330 used in the present embodiment is of 18 CFM (Cubic Feet per Minute; volume of cubic feet of air sent per minute) when DC (direct current) 24V is applied.

  FIG. 7A is an operation panel 210 that is installed in the exterior portion of the main body of the image forming apparatus 13 and serves as a user setting unit for setting the basis weight W of the recording material 1 as weight information per unit area of the recording material 1. Indicates. The operation panel 210 includes a display unit 211 that displays data input to and output from the CPU 200, and a numeric keypad 212 that serves as a numeric input unit. The CPU 200 also serves as user setting output means for outputting the setting information of the operation panel 210 to the memory 250.

The image forming apparatus 13 in the main body recording medium grammage detection unit 18 detect the basis weight W of the recording material 1 as the weight per unit volume of 1 is provided.

  The configuration of the basis weight detection unit 18 will be described with reference to FIG. The basis weight detection unit 18 includes an ultrasonic transmission unit 18 a and an ultrasonic reception unit 18 b that are arranged immediately after the registration roller 16 so as to sandwich a conveyance path for conveying the recording material 1. The ultrasonic transmission unit 18a has a piezoelectric element and a vibration member (not shown), and can irradiate ultrasonic waves by vibrating the vibration member with the piezoelectric element. The ultrasonic receiving unit 18b also has a vibrating member, and the vibrating member can receive ultrasonic waves by vibrating with the ultrasonic waves emitted from the ultrasonic transmitting unit 18a.

  Next, a method for detecting the basis weight of the recording material 1 will be described with reference to FIGS. The basis weight detection of the recording material 1 is performed in a state where the recording material 1 is temporarily stopped. In the block diagram of the control system shown in FIG. 18, an ultrasonic transmission signal 730 is sent from the CPU 200 to the transmission control unit 700. The transmission control unit 700 includes a drive signal generation unit 710 and an amplifier 720.

  The ultrasonic transmission signal 730 includes information on timing and frequency for driving the ultrasonic transmission unit 18a. A drive signal generation unit 710 in the transmission control unit 700 generates and outputs a drive signal 740 having a specified frequency (for example, 40 kHz) based on the ultrasonic transmission signal 730. The drive signal 740 has, for example, a frequency of 40 kHz. The drive signal 740 drives the piezoelectric element provided in the ultrasonic transmission unit 18a to vibrate the vibration member, thereby generating ultrasonic waves.

  The amplifier 720 amplifies the signal level of the drive signal 740 and outputs the amplified drive signal 750 to the ultrasonic transmitter 18a. With this drive signal 750, the ultrasonic transmitter 18a outputs, for example, an ultrasonic wave of 40 kHz.

  The ultrasonic receiving unit 18 b receives the ultrasonic wave transmitted through the recording material 1 from the ultrasonic transmitting unit 18 a and outputs an ultrasonic reception signal 830 to the reception calculating unit 800. The reception arithmetic unit 800 includes an amplifier 810, a smoothing circuit 820, and a rectifier circuit (not shown). Reception operation section 800 amplifies received signal 830 with amplifier 810. The amplified signal 840 is rectified by a rectifier circuit and then integrated by a smoothing circuit 820 to generate an arithmetic output 850.

The calculation output 850 increases in proportion to the output of the reception signal 830. When the output of the calculation output 850 is sufficiently obtained, the calculation output result obtained by the CPU 200 also serving as the basis weight detection result output means is output, and the basis weight of the recording material 1 is determined using this calculation output result.

In the present embodiment, the relationship between the basis weight (g / m ² ) of the recording material 1 and the calculation output 850 (V) is as shown in FIG. By 19, the basis weight of up to a basis weight of ^60g / ^{m 2 ~220g} / m 2 of the recording material 1 can be determined based on the calculated output 850 of the grammage detection unit 18 (V). The detection result detected by the basis weight detection unit 18 is output to the memory 250.

  As shown in FIG. 7A, in the display unit 211 of the operation panel 210, the user sets each mode set in advance according to the basis weight W of the recording material 1 that is the weight per unit volume of the recording material 1. To do. As an example of each mode, as shown in FIG. 7B, each mode of “thin paper 1a”, “thin paper 1b”, “plain paper 1c”, “plain paper 1d”, and “thick paper 1e” is the operation panel 210. Are displayed on the display unit 211, and are set by the user selecting as appropriate.

The mode set by the user is stored in the memory 250. The basis weight W of the recording material 1 is the weight of the recording material 1 per square meter expressed in grams (g). A memory 250 serving as a storage unit stores the basis weight W of the recording material 1 as basis weight information including weight information per unit area of the recording material 1 conveyed to the fixing device 300.

  At a predetermined position in the image forming apparatus 13 main body (image forming apparatus main body), as shown in FIG. 1, an atmospheric temperature detection means for detecting the atmospheric temperature in the image forming apparatus 13 main body (in the image forming apparatus main body) An ambient temperature detection unit 12 including a thermometer is provided.

  At a predetermined position in the main body of the image forming apparatus 13, as shown in FIG. 1, there is an atmospheric moisture amount detecting means for detecting the atmospheric temperature and the atmospheric humidity in the main body of the image forming apparatus 13 and calculating the atmospheric moisture amount. An atmospheric moisture amount detection unit 15 configured to include a thermometer and a hygrometer is provided.

  Here, E (t), which is the amount of atmospheric moisture, can be calculated by the following equation 1 using the temperature t measured by a thermometer and the humidity h measured by a hygrometer.

[Equation 1]
E (t) = 6.11 × 10 × (7.5 × t / (t + 237.3)) × h

Then, the ambient temperature information detected by the ambient temperature detecting section 12, and based on the basis weight W of the recording material 1 to be the basis weight information consisting of the weight information per unit area of the recording medium 1 stored in the memory 250, The CPU 200 controls the blowing operation by the blowing fan 330. Alternatively, based atmosphere moisture amount information detected by the atmospheric water content detecting section 15, and the basis weight W of the recording material 1 to be the basis weight information consisting of the weight information per unit area of the recording medium 1 stored in the memory 250 The CPU 200 controls the air blowing operation by the air blowing fan 330. Atmospheric temperature information and atmospheric moisture content information can be selected selectively or in combination by user settings.

  Next, the operation of the image forming apparatus 13 including the drive control of the blower fan 330, which is a feature of this embodiment, will be described with reference to the sequence charts shown in FIGS.

  In step S1 shown in FIGS. 8A and 8B, when a print job is input from a personal computer or the like, the main body of the image forming apparatus 13 starts an image forming operation. At this time, driving by the fixing device 300 starts.

Thereafter, in step S2 shown in FIGS. 8A and 8B, the image forming operation of the image forming process by the image forming apparatus 13 is started. Next, in step S <b> 3, drive control of the blower fan 330 is performed immediately before the recording material 1 enters the fixing device 300. FIG. 6A shows the relationship between the basis weight W of the recording material 1 and the input voltage V to the blower fan 330 in the present embodiment. In the present embodiment, the blower fan 330 is driven only when the basis weight W of the recording material 1 is less than 70 g / m ² which is a threshold value.

When the basic weight W of the recording material 1 is {W ≧ 70 g / m ² }, as shown in FIGS. 6A and 8A, the blower fan 330 is in a stopped state. When the basis weight W of the recording material 1 is {W <70 g / m ² }, as shown in FIGS. 6A and 8B, the blower fan 330 is moved from step S3 to step S4. Drive while.

At this time, the input voltage V to the blower fan 330 is set in advance by the user from the operation panel 210. Then, (basis weight information comprising weight information per unit area of the recording medium 1) information basis weight W of the recording material 1 stored in the memory 250, and the ambient temperature information detected by the ambient temperature detecting section 12 Based on this, the input voltage V to the blower fan 330 is appropriately determined.

  The input voltage V to the blower fan 330 is determined by heating the recording material 1 with the heater 316, so that moisture contained in the recording material 1 becomes water vapor and is condensed on the surface of the pressure roller 322. It is determined from the viewpoint of preventing the condensation slip generated by this. Further, the fixing film 320 is cooled by the air blow by the blower fan 330, and is determined as appropriate from the viewpoint of preventing a fixing failure that occurs due to the inability to secure a sufficient temperature for melting and fixing the toner.

  Condensation on the surface of the pressure roller 322 occurs when the recording material 1 is heated and the moisture contained in the recording material 1 is discharged as water vapor, and the atmosphere in the vicinity of the fixing nip 14 including the water vapor is discharged. This occurs when the water vapor amount exceeds the saturated water vapor amount with respect to the surface temperature of the pressure roller 322.

At this time, condensation slip is generated due to water droplets on the surface of the pressure roller 322. Therefore, the input voltage V of the blower fan 330 should be set to at least a predetermined minimum input voltage V _min so as to reduce below the saturation vapor amount for the surface temperature of the pressure roller 322 by the blowing of the blower fan 330.

Here, the amount of water vapor generated when the recording material 1 is heated is closely related to the basis weight W of the recording material 1. As the basis weight W of the recording material 1 is smaller, the temperature of the recording material 1 approaches 100 ° C., which is the boiling point temperature of water, and the amount of water vapor generated is larger. Therefore, set a larger minimum input voltage V _min of the recording material 1 having a basis amount as W is smaller blower fan 330 to increase the air blowing amount of air blowing fan 330, the temperature of the recording material 1 does not approach the boiling point temperature of the water Need to be cooled.

  On the other hand, from the viewpoint of securing good fixability of the unfixed toner 4 formed on the recording material 1, the fixability of the unfixed toner 4 on the recording material 1 is related to the temperature of the fixing film 320. Further, the surface temperature of the fixing film 320 tends to be lowered by being exposed to the air blown by the blower fan 330.

Therefore, the input voltage V of the blower fan 330, the temperature of the fixing film 320 must be greater than or equal to the temperature obtained good fixing property, it is necessary to set below a predetermined maximum input voltage V _max.

Here, the fixability of the recording material 1 is closely related to the basis weight W of the recording material 1, and the larger the basis weight W of the recording material 1, the more difficult the temperature of the recording material 1 rises. Is difficult. Accordingly, it is necessary to set the maximum input voltage V _max of the blower fan 330 to be larger as the basis weight W of the recording material 1 is larger.

That is, in the present embodiment, the input voltage V of the blower fan 330 is V _min as the minimum input voltage to the blower fan 330 and V as the maximum input voltage to the blower fan 330 according to the basis weight W of each recording material 1. _Assuming that _max , it is set in the range of {V _min ≦ V ≦ V _max }. As a result, it is possible to ensure both prevention of condensation slip and good fixability.

In steps S4 of FIGS. 8A and 8B, the recording material 1 is discharged out of the image forming apparatus 13, and the image forming operation is terminated. At this time, as shown in FIG. 8B, when the basis weight W of the recording material 1 is {W <70 g / m ² }, the driving of the blower fan 330 is stopped simultaneously.

  Next, the effect of this embodiment will be described with reference to FIG.

  FIG. 9 shows Example 1 in which drive control of the blower fan 330 is performed according to the basis weight W of each recording material 1 according to this embodiment. Furthermore, the comparative example 1 which did not drive the ventilation fan 330 at all is shown. Further, Comparative Example 2 in which the blower fan 330 is always driven regardless of the basis weight W of the recording material 1 is shown. The rate of occurrence of condensation slip for each recording material 1 having a basis weight W of each recording material 1 and the rate of occurrence of defective fixing of the unfixed toner 4 formed on the recording material 1 are shown.

  Here, the recording material A shown in FIG. 9 is “Ribbon K60 (trade name)” made of Nippon Paper manufactured by Nippon Paper Industries Co., Ltd. The recording material B is “CS680 (trade name)” made of Japanese paper manufactured by Canon Inc. The recording material D is “X-9 (trade name)” made of North American paper manufactured by Boise Cascade. As the recording material E, “Xerox 4024 (trade name)” made of North American paper manufactured by Xerox was used.

  Further, the basis weight W of the recording material 1 shown in FIG. In addition, as a scale representing the degree of flatness of the recording material 1, Nippon Kogyo measured the time required to pass 10 ml of air with a specified pressure difference between the glass surface and the surface of the recording material 1 by pressing them at a constant pressure. The Beck smoothness S defined in the standard JIS P 8119 is an actual measurement value.

The Beck smoothness S of the present embodiment is an optical flat finish, and a glass standard surface having an effective area of 10 cm ^{2 having} a circular hole through which air leaks in the center is 9.8 kPa ( Press at a pressure of 1 kg / cm ² ). And it is the measured value obtained by the Beck smoothness measuring method which measures the time (second; sec) required for 10 ml of air to pass by the predetermined pressure difference between them. The measurement value in this embodiment was a Beck smoothness meter manufactured by Kumagaya Riki Kogyo Co., Ltd.

  All the evaluations of the condensation slip and the fixing failure shown in FIG. 9 are performed in an environment where the ambient temperature detected by the ambient temperature detector 12 is 30 ° C., and the ambient relative humidity detected by the ambient moisture amount detector 15 is 80%. This is performed when the fixing device 300 is in a normal temperature state. Then, a set test of five recording materials 1 was performed 100 times each.

  Further, the recording material 1 shown in FIG. 9 is selected to have the same smoothness. The recording material 1 of the present embodiment has a Beck smoothness of about 5 sec to 20 sec.

  9 are all A4 size (210 mm × 297 mm) or LETTER size (8.5 inches × 11 inches; about 216 mm × about 279 mm).

  Then, during the condensation slip test, a solid image having a black K color of 100% is printed on the entire surface of the recording material 1. Further, during the fixing test, a solid image with a yellow Y color of 100% is printed on the entire surface of the recording material 1. Further, a solid image with 100% magenta M color printed on the entire surface of the recording material 1 was printed on the entire surface of the recording material 1 in a superimposed manner. In FIG. 9, the number of condensation slips and the number of fixing failures that occurred during 100 times are shown as “0/100”, for example.

  As shown in Comparative Example 1 in FIG. 9, when the blower fan 330 is kept stopped, if the basis weight W of the recording material 1 is small, the probability of condensation slip is high, and the basis weight of the recording material 1 is high. It can be seen that almost no condensation slips when W is large.

  This is because, when the basis weight W of the recording material 1 is small, the heat capacity of the recording material 1 is small, and the temperature of the recording material 1 approaches 100 ° C., which is the boiling point of water, and is contained in the recording material 1. This is because a large amount of water vapor is generated by evaporation of the water.

  Further, as shown in Comparative Example 2 in FIG. 9, when the blower fan 330 is constantly driven regardless of the basis weight W of the recording material 1, when the basis weight W of the recording material 1 is small, a fixing failure occurs. On the other hand, when the basis weight W of the recording material 1 is large, it can be seen that fixing failure is likely to occur.

  This is because when the blower fan 330 operates, the temperature rise of the fixing film 320 by the heater 316 is suppressed by the blown air. For this reason, the unfixed toner 4 cannot be sufficiently melted. In addition, when the basis weight W of the recording material 1 is large, the heat capacity of the recording material 1 is large. For this reason, the occurrence rate of fixing failure is higher than when the basis weight W of the recording material 1 is small.

  In order to prevent the occurrence of this fixing failure, the fixing film 320 may be heated by the heater 316 for a sufficient time. However, in this case, the FPOT (First Print Out Time) indicating the time required from when the print start button is pressed until the first recording material is discharged decreases. Further, PPM (Page Per Minute) indicating the print discharge amount per minute of the image forming apparatus is lowered.

  Therefore, when the drive control of the blower fan 330 is performed corresponding to the basis weight W of the recording material 1 of the present embodiment described above, the basis weight W of the recording material 1 is shown in Example 1 of FIG. When the air pressure is relatively small, the blower fan 330 operates to prevent condensation slip. On the other hand, when the basis weight W of the recording material 1 is relatively large, the blower fan 330 is not operated. For this reason, it can be seen that the occurrence of fixing failure can be prevented without lowering the performance of FPOT, PPM or the like.

  As described above, the drive control of the blower fan 330 is performed according to the basis weight W of the recording material 1 as in the present embodiment, without sacrificing the production performance of the aforementioned FPOT, PPM, and the like. It is possible to achieve both condensation slip and fixability.

In this embodiment, the basis weight W of the recording material 1 is automatically detected by the basis weight detection unit 18 that detects the basis weight W that is the basis weight information including the weight information per unit area of the recording material 1 in the main body of the image forming apparatus 13. To detect.

  Then, the detection result detected by the basis weight detection unit 18 is output to the memory 250 by the CPU 200. Then, the basis weight W of the recording material 1 entering the fixing device 300 is read from the memory 250 and the drive of the blower fan 330 is automatically controlled by the CPU 200.

  Note that the user may manually input information on the basis weight W of the recording material 1 from the operation panel 210 to the printer, or the user may input from the printer driver or the like in the personal computer.

In this embodiment, the blower fan 330 is driven only when the basis weight W of the recording material 1 is less than 70 g / m ^2. However, as shown in FIG. Accordingly, the air volume of the blower fan 330 may be varied step by step.

6B, when the basis weight W of the recording material 1 is less than 60 g / m ^{2, the} recording medium 1 is driven with the input voltage V to the blower fan 330 being 24V. Moreover, until the basis weight W is ^60g / ^{m 2 ~80g} / m 2 of the recording material 1, linearly decreases the input voltage V to the blower fan 330 to 0V from 24V. When the basis weight W of the recording material 1 is 80 g / m ² or more, an example is shown in which the input voltage V to the blower fan 330 is maintained at 0 V and stopped.

  Here, the fixing failure caused by the operation of the blower fan 330 occurs when the ambient temperature is low, and is less likely to occur when the ambient temperature is high. Accordingly, the blower fan 330 may be driven only in steps S2 to S4 shown in FIG.

  Also, the condensation slip is generated when the atmospheric moisture content is high, and is less likely to occur when the atmospheric moisture content is low. Therefore, the blower fan 330 may be driven only in steps S2 to S4 shown in FIG. 8 only when the atmospheric moisture content of the atmospheric moisture detection unit 15 is equal to or greater than a predetermined value.

  By narrowing down the conditions for occurrence of condensation slip and limiting the driving of the blower fan 330 as much as possible, the heat radiation of the fixing device 300 can be reduced. Therefore, it is possible to further improve the production performance of the image forming apparatus 13 such as FPOT and PPM.

According to the above configuration, the amount of air blown by the blower fan 330 is optimized for each recording material 1 according to the basis weight W that is the basis weight information including the weight information per unit area of the recording material 1. As a result, it is possible to suppress condensation slip and to ensure the fixability without degrading the performance of FPOT or PPM.

  Next, the configuration of the second embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. In addition, what was comprised similarly to the said 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.

In the first embodiment, the amount of air blown by the blower fan 330 is optimized for each recording material 1 in accordance with the basis weight W that is the basis weight information including the weight information per unit area of the recording material 1. In this embodiment, the amount of air blown by the blower fan 330 is optimized for each recording material 1 in accordance with the Beck smoothness S that is smoothness information per unit area of the recording material 1 conveyed to the fixing device 300.

  In the present embodiment, the configuration and control of the image forming apparatus 13 and the fixing apparatus 300 are substantially the same as those in the first embodiment.

  The present embodiment is different from the first embodiment in that the blower fan 330 is driven based on the Beck smoothness S that is smoothness information per unit area of the recording material 1.

  In the present embodiment, the memory 250 shown in FIG. 1 stores Beck smoothness S, which is smoothness information per unit area of the recording material 1 conveyed to the fixing device 300, as shown in FIG.

  Then, based on the ambient temperature information detected by the ambient temperature detection unit 12 shown in FIG. 1 and the Beck smoothness S that is the smoothness information per unit area of each recording material 1 stored in the memory 250, the CPU 200 The blowing operation by the blowing fan 330 is controlled.

  Further, based on the atmospheric water content information detected by the atmospheric water content detector 15 shown in FIG. 1 and the Beck smoothness S that is the smoothness information per unit area of each recording material 1 stored in the memory 250, The CPU 200 controls the blowing operation by the blowing fan 330. Atmospheric temperature information and atmospheric moisture content information can be selected selectively or in combination by user settings.

  Further, the operation panel 210 shown in FIG. 1 also serves as user setting means for setting the Beck smoothness S that is smoothness information per unit area of each recording material 1 by the user. The CPU 200 also serves as user setting output means for outputting setting information from the operation panel 210 serving as user setting means to the memory 250.

  In the present embodiment, as shown in FIG. 1, the image forming apparatus 13 main body is provided with a smoothness detector 19 serving as a smoothness detector for detecting the smoothness per unit area of each recording material 1. . As the smoothness detection unit 19, for example, a Beck smoothness meter manufactured by Kumagaya Riki Kogyo Co., Ltd. can be used. The CPU 200 also serves as smoothness detection result output means for outputting the detection result detected by the smoothness detection unit 19 to the memory 250.

  Heating by the fixing film 320 of the fixing device 300 evaporates moisture contained in the recording material 1 to generate water vapor, and condensation occurs on the pressure roller 322. In this case, when the recording material 1 has high smoothness, the frictional force of the recording material 1 itself is small, so that condensation slip is likely to occur. On the other hand, when the recording material 1 has low smoothness, the recording material 1 itself has a large frictional force, so that condensation slip hardly occurs. However, since the surface of the recording material 1 is rough, the toner and the recording material 1 are in close contact with each other and are difficult to fix.

  Therefore, the recording material 1 with high smoothness prevents condensation slip by driving the blower fan 330, and the recording material 1 with low smoothness such as rough paper having a rough texture and rough texture drives the blower fan 330. To ensure fixability. As a result, it is possible to achieve both condensation slip and securing of fixing property.

<Operation control of blowing means>
The operation control of the blower fan 330, which is a feature of this embodiment, will be described below.

  In the present embodiment, a method in which the user sets the smoothness information of the recording material 1 on the operation panel 210 will be described. As shown in FIG. 10, the user preliminarily Beck smoothness of the recording material 1 such as “smooth paper 1f”, “smooth paper 1g”, “smooth paper 1h”, “rough paper 1i”, “rough paper 1j”. Each mode according to S is selected and set.

  The Beck smoothness S of the recording material 1 selected and set from the display screen of the operation panel 210 is stored in the memory 250 in the main body of the image forming apparatus 13. In this embodiment, the Beck smoothness S of the recording material 1 is set by a user operation on the operation panel 210. In addition, the user may make settings from a printer driver or the like in the personal computer.

  Further, a smoothness detection unit 19 that detects the Beck smoothness S that is smoothness per unit area of the recording material 1 is provided in the main body of the image forming apparatus 13. Then, before the recording material 1 enters the fixing device 300, the Beck smoothness S of the recording material 1 is automatically detected by the smoothness detection unit 19. The detection result detected by the smoothness detection unit 19 may be output to the memory 250 by the CPU 200.

  The sequence for driving and controlling the blower fan 330 is the same as that of the first embodiment described above with reference to FIGS. 8A and 8B. In step S3 of FIGS. The difference is that the mode is set based on 1 Beck smoothness S.

  FIG. 11A shows an example of the relationship between the Beck smoothness S of the recording material 1 and the input voltage V to the blower fan 330 in the present embodiment. In this embodiment, the threshold value of the Beck smoothness S of the recording material 1 is 10 seconds. When the Beck smoothness S of the recording material 1 is smaller than 10 sec, the input voltage V to the blower fan 330 is set to 0 V and stopped. When the Beck smoothness S of the recording material 1 is 10 sec or more, the input voltage V to the blower fan 330 is set to 24 V, and the blower fan 330 is driven as shown in FIG.

  In FIG. 11B, when the Beck smoothness S of the recording material 1 is less than 10 sec, the input voltage V to the blower fan 330 is set to 0 V and stopped. Then, when the Beck smoothness S of the recording material 1 is 10 sec to 30 sec, the input voltage V to the blower fan 330 is linearly increased from 0V to 24V and driven. When the Beck smoothness S is 30 sec or more, an example in which the input voltage V to the blower fan 330 is maintained at 24V and driven is shown.

  At this time, the input voltage V to the blower fan 330 is set in advance by the user using the operation panel 210. Then, based on the information on the Beck smoothness S of the recording material 1 stored in the memory 250, the input voltage V to the blower fan 330 is determined from the viewpoint of preventing condensation slip and ensuring good fixability.

From the viewpoint of preventing condensation slip, the possibility of condensation slip when the surface of the pressure roller 322 is condensed differs depending on the Beck smoothness S of the recording material 1. That is, as the Beck smoothness S of the recording material 1 is higher, the frictional force with the pressure roller 322 is lower, so that condensation slip is more likely to occur. Therefore, it is necessary to set a large minimum input voltage V _min of the recording material 1 of the Bekk smoothness blower so S is as the condensation slip is not generated high fan 330.

On the other hand, from the viewpoint of securing good fixability, when the recording material 1 has a low Beck smoothness S, the degree of adhesion with the fixing film 320 is low. For this reason, the heat of the fixing film 320 cannot be sufficiently transmitted to the unfixed toner 4 on the recording material 1 and the fixability tends to deteriorate. Therefore, the lower the Bekk smoothness S of the recording medium 1, it is necessary to ensure the fixing property is set smaller the maximum input voltage V _max of the blower fan 330.

In the present embodiment, the input voltage V of the blower fan 330 is set such that the minimum input voltage to the blower fan 330 is V _min and the maximum input voltage to the blower fan 330 is V _max according to the Beck smoothness S of each recording material 1. Then, it is set in the range of {V _min ≦ V ≦ V _max }. Thereby, both prevention of condensation slip and securing of good fixability are achieved.

  Next, the effect of this embodiment will be described with reference to FIG.

  FIG. 12 shows Example 2 in which drive control of the blower fan 330 is performed based on the Beck smoothness S of the recording material 1 according to the present embodiment. Furthermore, as Comparative Example 1, a case where the blower fan 330 is not driven is shown. Further, as Comparative Example 2, a case where the blower fan 330 is always driven irrespective of the Beck smoothness S of the recording material 1 is shown. The rate of occurrence of condensation slip and the rate of occurrence of fixing failure for each recording material 1 having each Beck smoothness S are shown.

  The recording material F shown in FIG. 12 is GF600 (trade name) which is Japanese paper manufactured by Canon Inc. In addition, the recording material G is Ribbon K60 (trade name), a Japanese paper manufactured by Nippon Paper Industries Co., Ltd., the recording material H is a Chinese paper made by Beijing Paper Co., Ltd. (trade name), and the recording material I is NeenahBond, a North American paper made by Neenah Paper, was used. Further, the basis weight W of each of the recording materials F to I in FIG. 12 describes the specifications of each manufacturer, and the Beck smoothness S is an actual measurement value.

The evaluation shown in FIG. 12 is performed in an environment where the ambient temperature is 30 ° C. and the ambient relative humidity is 80%, when the fixing device 300 is in a normal temperature state, and each of the recording materials F to I has one set of tests. 100 times each. Further, the recording materials 1 shown in FIG. 12 are each selected to have the same basis weight W (basis weight 60 g / m ^{2 to} about 75 g / m ² ).

  All the sizes of the recording material 1 shown in FIG. 12 are A4 size. Regarding the printed image, a 100% solid image of black K is printed on the entire surface of the recording material 1 during the condensation slip test. Further, during the fixing failure test, a 200% solid image in which a 100% solid image of yellow Y and a 100% solid image of magenta M were superimposed was printed on the entire surface of the recording material 1. In FIG. 12, the number of condensation slips and the number of fixing failures that occurred during 100 times are shown as “0/100”, for example.

  When the state where the blower fan 330 is stopped as in Comparative Example 1, if the Beck smoothness S of the recording material 1 is large, the probability of condensation slip is high. It can also be seen that almost no condensation slip occurs when the recording material 1 has a small Beck smoothness S.

  This is because water vapor generated in the recording material 1 is heated to generate water vapor. The water vapor causes dew condensation on the surface of the pressure roller 322. At this time, if the Beck smoothness S of the recording material 1 is large, the frictional force between the surface of the pressure roller 322 and the recording material 1 is small, so that condensation slip is likely to occur.

  Further, when the blower fan 330 is always driven regardless of the Beck smoothness S of the recording material 1 as in Comparative Example 2, when the Beck smoothness S of the recording material 1 is large, there is almost no fixing failure. Nothing. On the other hand, when the Beck smoothness S of the recording material 1 is small, it can be seen that fixing failure is likely to occur.

  This is because when the recording material 1 has a large Beck smoothness S, the surface of the recording material 1 has large irregularities, and the melted toner is difficult to be fixed to the recording material 1. For this reason, fixing failure occurs. Further, when the drive control of the blower fan 330 is performed corresponding to the Beck smoothness S of the recording material 1 according to the present embodiment, the blower fan 330 is turned on when the Beck smoothness S of the recording material 1 is relatively large. Drive to prevent condensation slip. On the other hand, when the Beck smoothness S of the recording material 1 is relatively small, the blower fan 330 can be stopped to prevent occurrence of fixing failure.

  As in the present embodiment, drive control of the blower fan 330 is performed according to the Beck smoothness S of the recording material 1. Thus, FPOT (First Print Out Time) indicating the time required from when the print start button is pressed until the first recording material is discharged is not sacrificed. Further, production performance such as PPM (Page Per Minute) indicating the print discharge amount per minute of the image forming apparatus is not sacrificed. This makes it possible to achieve both condensation slip and fixing properties.

  In this embodiment, as shown in FIG. 11A, the blower fan 330 is driven only when the Beck smoothness S of the recording material 1 is 10 sec or more, but as shown in FIG. 11B. In addition, the blower fan 330 may be driven and controlled stepwise according to the Beck smoothness S of the recording material 1.

  Further, the condensation slip is likely to occur when the fixing device 300 is near the room temperature. Therefore, similarly to the first embodiment, the blower fan 330 may be driven only when the temperature detected by the thermistors 318 and 319 in the fixing device 300 is equal to or lower than a predetermined temperature.

  Further, the condensation slip is highly likely to occur in a high humidity condition where the amount of moisture contained in the recording material 1 is large. For this reason, as in the first embodiment, a hygrometer or a temperature / humidity meter is installed in the main body of the image forming apparatus 13. The blower fan 330 may be driven only when the predetermined humidity (or absolute humidity) is exceeded.

  By narrowing down the conditions for the occurrence of condensation slip and limiting the driving of the blower fan 330 as much as possible, the heat radiation of the fixing film 320 of the fixing device 300 can be reduced. As a result, the production performance of the image forming apparatus 13 such as FPOT or PPM can be further improved.

  As described above, by changing the air flow rate of the blower fan 330 according to the smoothness information of the recording material 1, the air flow rate of the blower fan 330 to the fixing device 300 can be optimized for each recording material 1. Therefore, it is possible to achieve both prevention of condensation slip by the blower fan 330 and suppression of fixing failure without deteriorating the production performance of the image forming apparatus 13 such as FPOT and PPM. Other configurations are the same as those in the first embodiment, and the same effects can be obtained.

  Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. In addition, what was comprised similarly to each said embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.

  In the present embodiment, both the first and second embodiments are provided. That is, the memory 250 stores basis weight W information that is weight information per unit area of the recording material 1 conveyed to the fixing device 300 and Beck smoothness S information that is smoothness information per unit area of the recording material 1. . Then, based on the basis weight W information and the Beck smoothness S information stored in the memory 250, the CPU 200 controls the blowing operation by the blowing fan 330.

  Further, the CPU 200 sends the air blown by the blower fan 330 based on the atmospheric temperature information detected by the atmospheric temperature detector 12 shown in FIG. 1 and the basis weight W information and Beck smoothness S information stored in the memory 250. It is also possible to control the operation.

  Further, the CPU 200 determines that the CPU 200 is based on the atmospheric moisture amount information detected by the atmospheric moisture amount detection unit 15 shown in FIG. 1 and the basis weight W information and Beck smoothness S information stored in the memory 250. It is also possible to control the air blowing operation. Atmospheric temperature information and atmospheric moisture content information can be selected selectively or in combination by user settings.

  In the present embodiment, the operation panel 210 serving as user setting means allows the user to use the basis weight W information as weight information per unit area of the recording material 1 and the Beck smoothing as smoothness information per unit area of the recording material 1. Degree S information is set. Then, the CPU 200 that also serves as the user setting output unit outputs the basis weight W information and the Beck smoothness S information set by the operation panel 210 to the memory 250.

  In the present embodiment, the weight and smoothness detecting means for detecting the weight per unit area and smoothness of the recording material 1 in the main body of the image forming apparatus 13 includes the basis weight detecting unit 18 and the smoothness detecting unit 19. Is done. Then, the CPU 200 also serving as the weight and smoothness detection result output unit outputs the detection result detected by the basis weight detection unit 18 and the smoothness detection unit 19 constituting the weight and smoothness detection unit to the memory 250.

  In the present embodiment, the schematic configuration and control of the image forming apparatus 13 and the fixing apparatus 300 are the same as those in the above embodiments.

  This embodiment is different from the above embodiments in that the blower fan 330 is driven based on the basis weight W information and the Beck smoothness S information of the recording material 1. This will be described in detail.

  As described in the above embodiments, the amount of water vapor generated in the recording material 1 varies depending on the basis weight W. Further, the frictional force with the pressure roller 322 varies depending on the Beck smoothness S. For this reason, there is a difference in the rate of occurrence of condensation slip even when the surface of the pressure roller 322 is condensed.

  Therefore, by combining the basis weight W information of the recording material 1 and the Beck smoothness S information, it is possible to narrow down conditions for condensation slip. In the present embodiment, the basis weight W information of the recording material 1 and the Beck smoothness S information are combined, and the blower fan 330 is driven based on the combination.

  In the present embodiment, a method in which the user sets basis weight W information and Beck smoothness S information of the recording material 1 on the operation panel 210 will be described. As shown in FIG. 13, the user selects “smooth / thin paper”, “smooth / plain paper”, “smooth / thick paper”, “rough / thin paper” according to the basis weight W of the recording material 1 and the Beck smoothness S, Select from “Rough / Plain” and “Rough / Thick” modes.

  The Beck smoothness S of the recording material 1 set from the operation panel 210 is stored in the memory 250 in the main body of the image forming apparatus 13. In this embodiment, the basis weight W of the recording material 1 is set by a user operation using the operation panel 210. In addition, the user may make settings from a printer driver or the like in the personal computer.

  Further, the basis weight detector 18 for detecting the weight per unit area of the recording material 1 and the smoothness detector 19 for detecting the smoothness per unit area of the recording material 1 are combined in the main body of the image forming apparatus 13. Weight and smoothness detection means are provided. Before the recording material 1 enters the fixing device 300, the basis weight W and the Beck smoothness S of the recording material 1 may be automatically detected by the basis weight detection unit 18 and the smoothness detection unit 19. .

  Then, the CPU 200 serving as the weight and smoothness detection result output means constituting the weight and smoothness detection means outputs the detection results detected by the basis weight detection unit 18 and the smoothness detection unit 19 to the memory 250.

FIG. 14 shows the experiment of condensation slip and fixing performance on various recording materials 1, the basis weight W of each recording material 1 is taken on the vertical axis of FIG. 14, and the Beck smoothness S of the recording material 1 is shown in FIG. It is a representation for the axis. Then, based on the basis weight W information of the various recording materials 1 and the Beck smoothness S information, the risk level of the condensation slip and the fixing performance of the recording material 1 are shown in regions Z _A , Z _B , Z _C shown in FIG. it is obtained by dividing the _{Z D.}

In Figure 14, high risk of the condensation slip of the recording material 1, fixing performance with good region Z _A. Furthermore, the risk of the condensation slip of the recording medium 1 is relatively high, the fixing performance have relatively good area Z _B. Furthermore, the risk of the condensation slip of the recording medium 1 is relatively low, the fixing performance has a relatively poor region Z _C. Additionally, low risk of the condensation slip of the recording material 1 has a fixing ability is poor region Z _D. This is an example in which these areas Z _A , Z _B , Z _C , and Z _D are divided so as not to overlap.

_A boundary line L1 between the region Z _A and the region Z _B shown in FIG. 14 is represented by an approximate expression of W = f1 (S), where W is the vertical axis and S is the horizontal axis. Here, the value of the function corresponding to the value of S is expressed as f1 (S). Similarly, the boundary line L2 of the region _{Z B,} a region _{Z C} shown in FIG. 14 is expressed by the approximate equation of W = f2 (S). Similarly, a region _{Z C} shown in FIG. 14, the boundary line L3 between the region _{Z D} is expressed by the approximate equation of W = f3 (S). W = f1 (S), W = f2 (S), and W = f3 (S) are stored in the memory 250 as approximate expressions of these boundary lines L1 to L3. Here, the regions Z _A , Z _B , Z _C , Z _D and the boundary lines L1, L2, L3 are regions obtained experimentally.

Then, for example, the basis weight W information and the Beck smoothness S information of the recording material 1 are acquired by the basis weight detection unit 18 and the smoothness detection unit 19. Then, the CPU 200 which also serves as the calculation means uses the acquired basis weight W information of the recording material 1 and the Beck smoothness S information as approximate expressions W = f1 (S), W = f2 (S), W = f3. By substituting in (S), it is calculated to which area area Z _A , Z _B , Z _C , Z _{D the} recording material 1 belongs.

For example, the Beck smoothness S information acquired by the smoothness detector 19 is substituted into W = f1 (S), W = f2 (S), and W = f3 (S) as approximate equations, and the basis weights W are substituted. Ask. The basis weight W information acquired by the basis weight detection unit 18 and the basis weight W obtained by W = f1 (S), W = f2 (S), and W = f3 (S) as the approximate expressions are large and small. It is possible to calculate which region Z _A , Z _B , Z _C , Z _D belongs to. These calculations are processed by the CPU 200 which also serves as a calculation means, and information on the areas Z _A , Z _B , Z _C and Z _D to which the recording material 1 found by the calculation belongs is stored in the memory 250.

FIG. 15 shows the relationship between the areas Z _A , Z _B , Z _C and Z _{D to} which the recording material 1 belongs and the input voltage V to the blower fan 330. In the region Z _A to the region Z _D , the input voltage V to the blower fan 330 is varied stepwise.

In the present embodiment sets the input voltage V of the high fusing risk of condensation slip is the area Z _A in the blower fan 330 is relatively good in 24V. The input voltage V to the area Z _B at the blower fan 330 is set to 12V. Setting the input voltage V to the area Z _C at blower fan 330 to 4V. The input voltage V to the area Z _D in the blower fan 330 is set to 0V.

  Next, the effect of this embodiment will be described with reference to FIG.

  Example 3 shown in FIG. 16 shows a case where drive control of the blower fan 330 is performed corresponding to the basis weight W of the recording material 1 according to the present embodiment and the Beck smoothness S. As a comparative example 1, a case where the blower fan 330 is not driven is shown. As Comparative Example 2, a case where the blower fan 330 is always driven irrespective of the basis weight W and the Beck smoothness S of the recording material 1 is shown. Further, the rate of occurrence of condensation slip and the rate of occurrence of fixing failure for each recording material 1 are shown.

  Here, the recording material J shown in FIG. 16 is GF600 (trade name) made of Japanese paper manufactured by Canon Inc. The recording material N is NeenahBond (trade name) made of North American paper manufactured by Neenah Paper. The recording material P is Extra (trade name) made of European paper manufactured by Canon Europe (EU). As the recording material Q, Xerox 4024 (trade name) made of North American paper manufactured by Xerox was used. Further, the basis weight W shown in FIG. 16 describes the specifications of each manufacturer, and the Beck smoothness S is an actual measurement value.

  All the evaluations shown in FIG. 16 were performed in an environment where the ambient temperature was 30 ° C. and the ambient relative humidity was 80%, when the fixing device 300 was at room temperature, and one set of tests was performed 100 times for each of five recording materials 1. It was.

  All the sizes of the recording material 1 shown in FIG. 16 are A4 size. Regarding the printed image, a 100% solid image of black K is printed on the entire surface of the recording material 1 during the condensation slip test. Further, during the fixing failure test, a 200% solid image in which a 100% solid image of yellow Y and a 100% solid image of magenta M were superimposed was printed on the entire surface of the recording material 1. In FIG. 16, the number of condensation slips and the number of fixing failures that occurred during 100 times are shown as “0/100”, for example.

  As can be seen from FIG. 16, compared with Comparative Examples 1 and 2, in this embodiment, the air volume of the blower fan 330 is determined in consideration of the basis weight W and Beck smoothness S of the recording material 1. It is possible to achieve both prevention of slip and securing of fixing property.

  As in this embodiment, drive control of the blower fan 330 is performed according to the basis weight W and Beck smoothness S of the recording material 1. Thus, FPOT (First Print Out Time) indicating the time required from when the print start button is pressed until the first recording material is discharged is not sacrificed. Further, production performance such as PPM (Page Per Minute) indicating the print discharge amount per minute of the image forming apparatus is not sacrificed. As a result, it is possible to achieve both condensation slip and fixability.

  Further, the condensation slip is likely to occur when the fixing device 300 is near the room temperature. For this reason, as in the above embodiments, the blower fan 330 may be driven only when the temperature detected by the thermistors 318 and 319 in the fixing device 300 is equal to or lower than a predetermined temperature.

  Further, there is a high possibility that dew condensation slip is generated under high humidity conditions where the amount of moisture contained in the recording material 1 is large. Therefore, as in the above embodiments, a hygrometer or a thermohygrometer is installed in the main body of the image forming apparatus 13, and the blower fan 330 is driven only when a predetermined humidity (or absolute humidity) is exceeded. Also good.

  As described above, by narrowing down the conditions for generating the condensation slip and limiting the driving of the blower fan 330 as much as possible, the heat radiation of the fixing film 320 of the fixing device 300 can be reduced. Thereby, it is possible to further improve the production performance of the image forming apparatus 13 such as FPOT and PPM.

  Further, in each of the above embodiments, as illustrated in FIG. 2, the configuration in which the blower fan 330 is disposed on the fixing film 320 side has been described as an example. In addition, as shown in FIG. 3, the same effect can be obtained with a configuration in which the blower fan 330 is disposed on the pressure roller 322 side.

  In each of the above embodiments, as shown in FIGS. 2 and 3, an example in which the blower fan 330 is disposed outside the device frame 324 has been described. However, the blower fan 330 may be disposed inside the device frame 324. Similar effects can be obtained.

According to the present embodiment, the blowing amount of the blowing fan 330 is varied according to the basis weight information including the weight information per unit area of the recording material 1 and the smoothness information per unit area. As a result, the amount of air blown by the blower fan 330 into the fixing device 300 can be optimized for each recording material 1. For this reason, it is possible to achieve both prevention of condensation slip and suppression of occurrence of fixing failure by blowing by the blower fan 330 without lowering the production performance of the image forming apparatus 13 such as FPOT and PPM.

1 ... Recording material
200 ... CPU (control unit ; user setting output means; basis weight detection result output means; smoothness detection result output means; basis weight and smoothness detection result output means)
250 ... Memory (memory means)
300 ... Fixing device (fixing part )
330… Blower fan (Blower means)
W ... Basis weight (basis weight information consisting of weight information per unit volume)

Claims (10)

An image forming unit for forming a toner image on a recording material ;
A heating rotary member, wherein the rollers forming a nip with the heating rotating body, has, fixed on the recording material the toner image by heating pressurized while conveying the recording material on which the toner image is formed by the nip A fixing unit that
It has a blower fan, a blower for blowing air toward the roller,
A control unit for controlling power supplied to the blower fan ;
A basis weight detector for detecting the basis weight of the recording material ;
In an image forming apparatus having
When the virtual surface including the nip portion is divided into two regions, a region where the heating rotator is present and a region where the roller is present, the air outlet of the air blowing portion is Provided in an area on one side ,
The controller supplies power to the blower fan when a recording material having a small basis weight is being conveyed at the nip portion than when a recording material having a large basis weight is being conveyed at the nip portion. An image forming apparatus that is controlled to be large . There is an ambient temperature detection means for detecting the ambient temperature in the image forming apparatus main body,
Based on the ambient temperature information detected by the ambient temperature detection means and the basis weight information of the recording material detected by the basis weight detection unit , the control unit controls the power supplied to the blower fan. The image forming apparatus according to claim 1. In the image forming apparatus main body, there is an atmospheric moisture amount detecting means for detecting the atmospheric temperature and atmospheric humidity and calculating the atmospheric moisture amount,
Controlling the electric power supplied to the blower fan by the control unit based on the atmospheric moisture amount information detected by the atmospheric moisture amount detection unit and the basis weight information of the recording material detected by the basis weight detection unit. The image forming apparatus according to claim 1. User setting means for the user to set the basis weight information of the recording material;
And user setting output means for output the setting information of the user setting means,
The image forming apparatus according to claim 2, further comprising: The image forming apparatus according to claim 2 or claim 3 characterized in that it has a grammage detection result output means to output the detection result of the detection by the grammage detection unit. An image forming unit for forming a toner image on a recording material ;
A heating rotary member, wherein the rollers forming a nip with the heating rotating body, has, fixed on the recording material the toner image by heating pressurized while conveying the recording material on which the toner image is formed by the nip A fixing unit that
It has a blower fan, a blower for blowing air toward the roller,
A control unit for controlling power supplied to the blower fan ;
A smoothness detector for detecting the smoothness of the recording material ;
In an image forming apparatus having
When the virtual surface including the nip portion is divided into two regions, a region where the heating rotator is present and a region where the roller is present, the air outlet of the air blowing portion is Provided in an area on one side ,
The controller supplies power to the blower fan when the recording material with high smoothness is conveyed at the nip portion than when the recording material with low smoothness is conveyed at the nip portion. An image forming apparatus that is controlled to be large . There is an ambient temperature detection means for detecting the ambient temperature in the image forming apparatus main body,
Ambient temperature information detected by said ambient temperature detection means, and based on the flat lubricity information recording medium detected by the smoothness sensing unit, said control unit controls the power supplied to the blower fan The image forming apparatus according to claim 6. In the image forming apparatus main body, there is an atmospheric moisture amount detecting means for detecting the atmospheric temperature and atmospheric humidity and calculating the atmospheric moisture amount,
Based on the ambient water content atmosphere moisture amount information detected by the detecting means, and a flat sliding property information of the recording material detected by the smoothness sensing unit, the control unit controls the power supplied to the blower fan The image forming apparatus according to claim 7 . A user setting means for a user to set a flat lubricity information recording medium,
And user setting output means for output the setting information of the user setting means,
The image forming apparatus according to claim 7, further comprising: The image forming apparatus according to claim 7 or claim 8 characterized in that it has a smoothness detection result output means to output the detection result of the detection by the previous SL smoothness detection unit.

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