JP2005043685A - Image forming method and apparatus used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method, in which a defect in an image or collapse in color balance is not generated, in forming the full color image by an intermediate transfer system using fine grain polymerized toner, even when it is performed successively for a long a period of time. <P>SOLUTION: In the image forming method for forming the image by the intermediate transfer system, using the toner having the number average particle diameter of 3-8 μm, the temperature of a developer is ≤48°C, the temperature of an image carrier in the vicinity of a cleaning means is ≤55°C, and the temperature of an intermediate transfer body in the vicinity of the cleaning means is ≤59°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming method and an apparatus used therefor, and more particularly to an image forming method capable of obtaining a high-quality image by an intermediate transfer method and an apparatus used therefor.

  Conventionally, an image forming method using an intermediate transfer member is known as a method for transferring a toner image on an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) to a recording material. This method is known as an electrophotographic photosensitive member. In the process of transferring the toner image from the toner to the recording material, another transfer process is performed. After the primary transfer from the electrophotographic photosensitive member to the intermediate transfer member, the primary transfer image of the intermediate transfer member is secondarily transferred to the recording material. To get the final image. This method is often employed as a superimposing transfer method for each color toner image in a so-called full-color image forming apparatus that reproduces a color-separated document image using subtractive color mixing with toners such as black, cyan, magenta, and yellow. .

  As the toner used for this, conventionally used pulverized toner has an indefinite shape and a wide particle size distribution, so the charge amount distribution is also wide, to improve the reproducibility of dot shapes and fine lines, and the sharpness of the edges. Since there is a limit and it is difficult to meet the demand for higher image quality in recent years, polymerized toner has been adopted.

  This is because the polymerization method toner produced by the polymerization method has a uniform shape and particle size distribution, and thus exhibits stable development and transfer characteristics and is an effective means for improving image quality.

  In general, residual toner remaining on the electrophotographic photosensitive member after the primary transfer from the electrophotographic photosensitive member to the intermediate transfer member is cleaned by a cleaning unit, and remains on the intermediate transfer member after the secondary transfer to the recording material. The transfer residual toner is cleaned by the cleaning means.

On the other hand, in an electrophotographic image forming apparatus, the temperature of each part is controlled for various purposes. For example, Patent Document 1 discloses that the supply and recovery of each developer are independently performed according to the temperature change in each developer unit of black, cyan, magenta, and yellow to prevent image quality deterioration due to temperature rise. Document 2 describes that the developer temperature is kept at 30 to 40 ° C. in order to prevent fluctuations in the developer dynamic resistance caused by a decrease in developer temperature and to prevent a decrease in toner density. Are listed.
JP 2000-321856 A Japanese Patent Laid-Open No. 10-48934

  Using a fine polymerization toner having a number average particle diameter of 3 to 8 μm, which is advantageous for high image quality, particularly resolution, as described above, a full color image is formed over a long period of time or continuously by an intermediate transfer method. In other words, problems such as missing images and loss of color balance due to defective transfer of specific colors may occur.

  The present invention has been made in view of the above circumstances, and when a full color image is formed by an intermediate transfer method using a fine polymerization toner, the image is lost or the color balance is lost even if it is continuously performed for a long period of time. It is an object of the present invention to provide an image forming method in which no occurrence occurs.

The above object of the present invention is to
1) A step of forming a latent image on the image carrier, a step of developing the latent image with a developer containing toner having a number average particle diameter of 3 to 8 μm, and an intermediate transfer of the toner image formed on the image carrier A step of transferring the toner image to the intermediate transfer member, a step of cleaning the image carrier after transferring the toner image to the intermediate transfer member, a step of transferring the toner image transferred and formed on the intermediate transfer member to the recording paper, and an intermediate after transferring the toner image to the recording paper. And a step of cleaning the transfer member, wherein the temperature of the developer is 48 ° C. or less, the temperature near the cleaning unit for the image carrier is 55 ° C. or less, and the temperature near the cleaning unit for the intermediate transfer member is 59 ° C. or less. An image forming method for forming an image;
2) Means for forming a latent image on the image carrier, means for developing the latent image with a developer containing toner having a number average particle diameter of 3 to 8 μm, and intermediate transfer of the toner image formed on the image carrier Primary transfer means for transferring to the body, means for cleaning the image carrier after transferring the toner image to the intermediate transfer body, secondary transfer means for transferring the toner image transferred and formed on the intermediate transfer body to the recording paper, and recording the toner image Means for cleaning the intermediate transfer member after transfer to paper, the temperature of the developer is 48 ° C. or less, the temperature in the vicinity of the cleaning means for the image carrier is 55 ° C. or less, and the temperature in the vicinity of the cleaning means for the intermediate transfer member is 59 ° C. An image forming apparatus having means for controlling:
3) An image forming apparatus having a fan for exhausting air and a duct for deriving exhaust air from the fan, and having an exhaust means whose opening at the most downstream part of the duct is larger than that of the fan part
4) a step of forming a latent image on the image carrier, a step of developing the latent image with a developer containing toner, a step of transferring the toner image formed on the image carrier to an intermediate transfer member, and a toner image A step of cleaning the image carrier after transfer to the intermediate transfer member, a step of transferring the toner image transferred and formed on the intermediate transfer member to the recording paper, and a step of cleaning the intermediate transfer member after transferring the toner image to the recording paper. An image forming method in which the operation is temporarily stopped at a timing set by a transition of the temperature of the developer during continuous image formation, and a cooling period is provided;
5) means for forming a latent image on the image carrier, means for developing the latent image with a developer containing toner, primary transfer means for transferring the toner image formed on the image carrier to the intermediate transfer member, toner Means for cleaning the image carrier after transferring the image to the intermediate transfer body, secondary transfer means for transferring the toner image transferred and formed on the intermediate transfer body to the recording paper, and cleaning the intermediate transfer body after transferring the toner image to the recording paper The image carrier, the developer and the intermediate transfer member, the operation is temporarily stopped at a timing set by the transition of the temperature of the developer during continuous image formation, and the image carrier, developer and intermediate transfer An image forming apparatus having control means for cooling at least one selected from the body;
Achieved by:

  That is, the present inventor has high adhesion due to the fine particles of toner, particularly polymerized toner. When the temperature inside the image forming apparatus rises, the toner adheres to the cleaning member, thereby causing image omission or missing of specific color toner. As a result, the developer temperature, the temperature in the vicinity of the image bearing member cleaning means, and the temperature in the vicinity of the intermediate transfer member cleaning means are determined, and the upper limit temperatures are found to arrive at the present invention. It was.

  In carrying out the control according to the present invention, as a means for cooling at least one selected from the image carrier, the developer, and the intermediate transfer member, the duct that draws exhaust air from the fan more than the opening of the fan part is used. Use of an exhaust means having a larger opening at the downstream portion is advantageous in suppressing an increase in temperature.

  Further, when the temperature rises during continuous operation, the cooling period is provided by forcibly stopping, but it is preferable to set the timing based on the transition data of the developer temperature during continuous image formation.

  As will be demonstrated in the examples described later, according to the image forming method of the present invention, even if a full-color image is continuously formed for a long period of time by an intermediate transfer method using finely divided polymerization toner, image leakage and color balance are achieved. No collapse occurs.

  Hereinafter, although this invention is demonstrated using embodiment, this invention is not limited to this.

  FIG. 1 shows a schematic cross-sectional view of a color image forming apparatus as an example of an image forming apparatus used in the image forming method of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7, and a paper feeding / conveying means (reference numeral None) and a fixing device 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  An image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first image carrier, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y disposed around the photoconductor 1Y, A primary transfer roller 5Y as a primary transfer unit and a cleaning unit 6Y are provided. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposing unit 3M, and a developing unit 4M disposed around the photosensitive unit 1M. A primary transfer roller 5M as a primary transfer unit and a cleaning unit 6M are provided. An image forming unit 10C for forming a cyan image includes a drum-shaped photoconductor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, and a developing unit 4C arranged around the photoconductor 1C. A primary transfer roller 5C as a primary transfer unit and a cleaning unit 6C are provided. The image forming unit 10K that forms a black image includes a drum-shaped photoconductor 1K as a first image carrier, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a primary transfer arranged around the photoconductor 1K. A primary transfer roller 5K and a cleaning means 6K are provided as means.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  The toner images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K, and are combined. A colored image is formed.

  After the toner image is transferred to the intermediate transfer body 70, the remaining toner is removed by the cleaning units 6Y, 6M, 6C, and 6K on the photoreceptors 1Y, 1M, 1C, and 1K. In addition, in the vicinity of the cleaning units 6Y, 6M, 6C, and 6K, temperature detection units (not shown) are provided on the upstream side in the photoconductor rotation direction.

  The transfer material P as a recording medium accommodated in the paper feeding cassette 20 is fed by the paper feeding means 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and registration rollers 23, and then the secondary transfer means 5A. The color images are transferred onto the transfer material P at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing device 24. In some cases, the transfer material P passes through a curl correcting device 80 installed on the downstream side of the transfer material P and is sandwiched between the paper discharge rollers 25 to be discharged outside the machine. Placed on top.

  When image formation on the transfer material P is performed on both sides, the paper discharge switching member 170 is switched, the paper guide portion 177 is opened, and the transfer material P is conveyed in the direction of the broken line arrow.

  Further, the transfer material P is transported downward by the transport mechanism 178 and is switched back by the paper reversing unit 179, and the rear end portion of the transfer material P is transported into the duplex copying paper supply unit 130 as the leading end portion. .

  The transfer material P moves in the paper feeding direction in the conveyance guide 131 provided in the double-sided copying paper feeding unit 130, is re-fed by the paper feeding roller 132, and is guided to the conveyance path 22.

  As described above, the transfer material P is conveyed again to the secondary transfer position, the toner image is transferred to the back surface of the transfer material P, fixed by the fixing device 24, and then discharged to the discharge tray 26.

  After the color image is transferred to the transfer material P by the secondary transfer means 5A, the residual toner is removed from the endless belt-shaped intermediate transfer body 70 from which the transfer material P is separated by the curvature by the cleaning means 6A. Similarly, a temperature detecting unit 90 is provided on the upstream side of the cleaning unit 6A in the running direction of the intermediate transfer member.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rollers 5Y, 5M, and 5C are pressed against the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer means 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer means 5A.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10K and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5K, and cleaning means 6A. Consists of.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  FIG. 2 is a model diagram in which the image forming unit 10Y and the intermediate transfer body unit 7 in the vicinity thereof are partially enlarged.

  The cleaning means 6Y has a cleaning blade 6Y1 as a cleaning member and a brush roller 6Y2 as an auxiliary cleaning member, and the cleaning means 6A for the intermediate transfer member has a cleaning blade 6A1 as a cleaning member. TSY and 90 are temperature sensors (temperature detection means) arranged upstream of the cleaning means in the rotation direction of the photosensitive member and upstream of the running direction of the intermediate transfer member, respectively. The developing unit 4Y includes a temperature sensor (temperature detecting unit) 41 that detects the developer temperature.

  The present invention uses a developer containing toner having excellent resolution and sharpness and a number average particle diameter of 3 to 8 μm. When an image is formed by an intermediate transfer method, the toner is applied to the cleaning member when the temperature inside the image forming apparatus rises. As a result, the developer temperature is 48 ° C. or lower, the temperature in the vicinity of the image carrier cleaning means is 55 ° C. or lower, and the intermediate transfer member is in the vicinity of the cleaning means. The temperature is controlled to 59 ° C. or less to eliminate the temperature.

  Specific means include, for example, a cooling fan for lowering the ambient temperature of the developing means 4Y, 4M, 4C, and 4K, a cooling fan for lowering the ambient temperature of the photoreceptors 1Y, 1M, 1C, and 1K, and the periphery of the intermediate transfer unit. A cooling fan, etc. is installed to lower the temperature, and the fan is turned on / off according to the temperature detected by the temperature detection means, or it operates according to the transition of the developer temperature during continuous image formation. Is forcibly stopped and a cooling period is provided.

  The number average particle diameter of the toner can be measured using a Coulter counter, Coulter Multisizer (manufactured by Coulter Electronics Co., Ltd.), SLAD 1000 (Laser diffraction type particle size measuring apparatus manufactured by Shimadzu Corporation), or the like.

  In performing the control for suppressing the temperature rise, it is advantageous to use an exhaust means having a larger opening at the most downstream portion of the duct for exhausting air from the fan than at the opening of the fan portion.

  FIG. 3 schematically shows an example of the shape of such an exhaust means 30 viewed from the inside of the apparatus.

  The fan 31 is installed in the opening 32 portion of the apparatus wall and is controlled to be rotated / stopped by driving means (not shown). Reference numeral 33 denotes a duct for guiding the exhaust air, and the opening 34 of the exhaust air outlet at the most downstream portion has a larger area than the opening 32. Note that a filter 35 may be provided in the vicinity of the exhaust air outlet.

  FIG. 4 schematically shows an example of the transition of the developer temperature accompanying the operation of the apparatus.

As shown in the figure, the temperature changes in reality depend on the environmental temperature, the timing leading to the set temperature of the forced stop, at ambient temperature t ₁ Tm1, at ambient temperature t ₂ Tm2, at ambient temperature t ₃ as in the Tm3 Different. Therefore, the ambient temperature (which is approximated by, for example, the temperature of the developer at the start of image formation) obtained based on the transition of the developer temperature in continuous image formation and the forced stop timing are tabulated. It is preferable to perform control to forcibly stop and provide a cooling period when the time is reached in a continuous operation under a certain environmental temperature. However, it is needless to say that the time is reached and the image is paused after waiting for the separation of images to be formed (the end of one job or the end when a large number of identical images are formed).

  FIG. 5 is a functional block diagram of the image forming apparatus of the present invention.

  The main body CPU 50 as the control means according to the present invention forms a latent image on the image carrier based on the temperature detected by the developer temperature detection means 41, the image carrier temperature detection means TS, and the intermediate transfer body temperature detection means 90. Means for developing the latent image with a developer containing toner having a number average particle size of 3 to 8 μm, primary transfer means for transferring the toner image formed on the image carrier to the intermediate transfer member, and toner image Means for cleaning the image carrier after transfer to the intermediate transfer body, secondary transfer means for transferring the toner image transferred and formed on the intermediate transfer body to the recording paper, means for cleaning the intermediate transfer body after transferring the toner image to the recording paper In addition, the operation of the image forming unit 10 including a fixing device, a sheet feeding unit, and a conveying unit, the developer cooling unit 42 including a fan, the image carrier cooling unit 43, and the intermediate transfer body cooling unit 44 are controlled.

  The ROM 51 is a storage means storing a table in which the environmental temperature and the forced stop timing are associated, and a control program according to the present invention. The CPU 50 controls the operation of each unit while referring to the table and the program.

  FIG. 6 shows a flowchart of an example of the operation according to the image forming method of the present invention.

  The document image is read, and the processing starts simultaneously with the standby for image formation. It is determined whether or not the developer temperature is equal to or lower than the cooling (fan) operation start set temperature (step S1). If the developer temperature exceeds the set temperature (NO in step S1), the cooling operation is started (step S2). It is determined whether the temperature is 48 ° C. or lower (step S3). If the temperature is 48 ° C. or lower, the process proceeds to step S4. If the developer temperature exceeds 48 ° C., the image formation is temporarily stopped and a standby state is awaited until the temperature condition is satisfied (step S13).

  Next, it is determined whether the image carrier temperature is equal to or lower than the cooling (fan) operation start set temperature (step S4). If the temperature exceeds the set temperature (NO in step S4), the cooling operation is started (step S5). It is determined whether the body temperature is 55 ° C. or less (step S6), and if it is 55 ° C. or less, the process proceeds to step S7. If the image carrier temperature exceeds 55 ° C., the image formation is temporarily stopped, and a standby state is awaited until the temperature condition is satisfied (step S13).

  Further, it is determined whether the intermediate transfer body temperature is equal to or lower than the cooling (fan) operation start set temperature (step S7). If the temperature exceeds the set temperature (NO in step S7), the cooling operation is started (step S8), and further, the intermediate transfer is performed. It is determined whether the body temperature is 59 ° C. or less (step S9), and if it is 59 ° C. or less, the process proceeds to step S10. If the intermediate transfer member temperature exceeds 59 ° C., the image formation is temporarily stopped and a standby state is awaited until the temperature condition is satisfied (step S13).

  If the developer temperature, the image carrier temperature, and the intermediate transfer member temperature are not more than the cooling (fan) operation start set temperature, the process proceeds to step S10 as it is.

  During the image formation, the CPU 50 refers to the ROM 51 to determine whether the time until the forced stop set corresponding to the environmental temperature has elapsed (step S11). It waits in a standby state until it is satisfied (step S13).

  When the detected temperatures of the developer, the image carrier, and the intermediate transfer member are 48 ° C. or lower, 55 ° C. or lower, and 59 ° C. or lower, respectively (step S14), steps S1 to S11 are repeated for image formation (step S12). When the image formation is finished, the process is finished.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this.

  In the image forming apparatus of FIG. 1, a volume average particle diameter obtained by coating a polymerization resin toner of each color having a number average particle diameter of 3 to 8 μm mainly composed of styrene-acrylic resin, carbon black, and a colorant with a silicone resin. The following evaluation was performed by changing the temperature conditions of the developer, the photoconductor, and the intermediate transfer belt by using a developer prepared by mixing a 60 μm ferrite carrier and adjusting the toner concentration to 6%.

(Example 1-1)
Continuous image formation was performed for 3 hours under the condition of cooling the photoreceptor and the intermediate transfer belt. The developer temperature was 47 ° C., the photoreceptor temperature was 51 ° C., and the intermediate transfer belt temperature was 55 ° C.

(Example 1-2)
Continuous image formation for 3 hours was performed under the condition of cooling the developing unit and the intermediate transfer belt. The developer temperature was 45 ° C., the photoreceptor temperature was 54 ° C., and the intermediate transfer belt temperature was 55 ° C.

(Example 1-3)
Continuous image formation was carried out for 3 hours under conditions for cooling the developing unit and the photoreceptor. The developer temperature was 45 ° C., the photoreceptor temperature was 51 ° C., and the intermediate transfer belt temperature was 58 ° C.

(Example 1-4)
Continuous image formation was performed for 3 hours under the condition of cooling the developing unit, the photoconductor, and the intermediate transfer belt. The developer temperature was 45 ° C., the photoreceptor temperature was 51 ° C., and the intermediate transfer belt temperature was 55 ° C.

(Comparative Example 1)
Continuous image formation for 3 hours was performed without cooling the developing unit at all. The developer temperature was 53 ° C., the photoreceptor temperature was 51 ° C., and the intermediate transfer belt temperature was 55 ° C.

(Comparative Example 2)
Continuous image formation for 3 hours was performed without cooling the periphery of the photoreceptor. The developer temperature was 45 ° C., the photoreceptor temperature was 60 ° C., and the intermediate transfer belt temperature was 55 ° C.

(Comparative Example 3)
Continuous image formation for 3 hours was performed without cooling the periphery of the intermediate transfer belt. The developer temperature was 45 ° C., the photoreceptor temperature was 51 ° C., and the intermediate transfer belt temperature was 63 ° C.

(Comparative Example 4)
Continuous image formation for 3 hours was performed without operating any direct cooling means of the developing unit, the photosensitive member and the intermediate transfer belt. The developer temperature was 55 ° C., the photoreceptor temperature was 58 ° C., and the intermediate transfer belt temperature was 62 ° C.

"Evaluation item"
(Image white blank)
After continuous image formation, the number of partial white spots was evaluated with a uniform image pattern having a reflection density of 1.3.

◎: No problem at zero ○: Acceptable level at 1-5 ×: Level of practical problem at 6 or more (vertical stripes)
After continuous image formation, the occurrence of vertical streaks in a halftone image having a reflection density of 0.8 was evaluated.

◎: Not generated at all ○: Slightly generated, allowable level ×: Generated and practically problematic level (Rough image (uneven density))
After continuous image formation, the occurrence of image roughness (density unevenness) in a halftone image having a reflection density of 0.3 was evaluated.

◎: No occurrence ○: Slight occurrence and acceptable level ×: Occurrence and practically problematic level << Image forming conditions >>
Image formation line speed L / S: 180 mm / s
Charging condition of the photoconductor: The potential of the non-image portion is detected by a potential sensor and can be feedback-controlled. The controllable range is −500 V to −900 V, and the surface potential of the photoconductor when fully exposed is − The range was 50 to 0V.

Image exposure light: Semiconductor laser (wavelength: 780 nm)
Development method: Reversal development Intermediate transfer member: Endless belt made of silicone rubber mixed with carbon black (volume resistivity is 1 × 10 8 Ω · cm)
Primary transfer roller (5Y, 5M, 5C, 5K in FIG. 1 (6.05 mmφ for each)): Configuration in which elastic rubber is attached to a core metal: surface resistivity 1 × 10 6 Ω
Fixing: Thermal fixing method Photoconductor cleaning means Cleaning blade: Rubber elastic body with 55% rebound resilience Cleaning brush: Conductive acrylic resin, brush hair density (3 × 10 ³ / cm ² )
Secondary transfer roller (5A in FIG. 1): Configuration in which elastic rubber is attached to the core metal: Application of transfer voltage Cleaning means for intermediate transfer member Cleaning blade: Rubber elastic body with rebound resilience of 40% With cleaning roller The results are shown below.

Image white stripe Vertical stripe Image roughness Example 1-1 ○ ◎ ◎
Example 1-2 ◎ ○ ◎
Example 1-3 ◎ ◎ ○
Example 1-4 ◎ ◎ ◎
Comparative Example 1 × ◎ ◎
Comparative Example 2 ◎ × ◎
Comparative Example 3 ◎ ◎ ×
Comparative Example 4 × × ×

1 is a cross-sectional configuration diagram showing an outline of an example of an image forming apparatus used in an image forming method of the present invention. FIG. 3 is a model diagram in which an image forming unit 10Y and an intermediate transfer body unit 7 in the vicinity thereof are partially enlarged. It is a figure which shows typically the example of the shape of the preferable exhaust means seen from the inside of an apparatus. FIG. 5 is a diagram schematically illustrating an example of a change in developer temperature accompanying the operation of the apparatus. 1 is a functional block diagram of an image forming apparatus of the present invention. 5 is a flowchart of an example of an operation according to the image forming method of the present invention.

Explanation of symbols

1Y, 1M, 1C, 1K photoconductor 2Y, 2M, 2C, 2K charging means 3Y, 3M, 3C, 3K exposure means 4Y, 4M, 4C, 4K developing means 5Y, 5M, 5C, 5K primary transfer roller 5A secondary transfer Means 6Y, 6M, 6C, 6K, 6A Cleaning means 7 Intermediate transfer unit 10Y, 10M, 10C, 10K Image forming unit 20 Paper feed cassette 21 Paper feed means 23 Registration roller 24 Fixing device 26 Paper discharge tray 25 Paper discharge roller 30 Exhaust means 70 Intermediate transfer body 80 Curl correction device 90 Intermediate transfer body temperature detection means 130 Double-sided copy paper feed unit 170 Paper discharge switching member 177 Paper guide part 179 Paper reversing part A Image forming apparatus main body SC Document image reading apparatus P Transfer material

Claims (5)

A step of forming a latent image on the image carrier, a step of developing the latent image with a developer containing toner having a number average particle diameter of 3 to 8 μm, and a toner image formed on the image carrier as an intermediate transfer member A step of transferring, a step of cleaning the image carrier after transferring the toner image to the intermediate transfer member, a step of transferring the toner image transferred and formed on the intermediate transfer member to the recording paper, and an intermediate transfer member after transferring the toner image to the recording paper Forming the developer at a temperature of 48 ° C. or less, a temperature in the vicinity of the image carrier cleaning means of 55 ° C. or less, and a temperature in the vicinity of the intermediate transfer member cleaning means of 59 ° C. or less. An image forming method. Means for forming a latent image on the image carrier, means for developing the latent image with a developer containing toner having a number average particle diameter of 3 to 8 μm, and a toner image formed on the image carrier as an intermediate transfer member Primary transfer means for transferring, means for cleaning the image carrier after transferring the toner image to the intermediate transfer body, secondary transfer means for transferring the toner image transferred and formed on the intermediate transfer body to the recording paper, and toner image on the recording paper Means for cleaning the intermediate transfer member after transfer, the temperature of the developer is 48 ° C. or less, the temperature in the vicinity of the cleaning means for the image carrier is 55 ° C. or less, and the temperature in the vicinity of the cleaning means for the intermediate transfer member is 59 ° C. or less. An image forming apparatus having a control means. An image forming apparatus having a fan for exhausting air and a duct for extracting exhaust air from the fan, and having an exhaust means having an opening at a most downstream portion of the duct larger than an opening of the fan portion. A step of forming a latent image on the image carrier, a step of developing the latent image with a developer containing toner, a step of transferring the toner image formed on the image carrier to an intermediate transfer member, and an intermediate transfer of the toner image A step of cleaning the image carrier after transfer to the body, a step of transferring the toner image transferred and formed on the intermediate transfer member to the recording paper, and a step of cleaning the intermediate transfer member after transferring the toner image to the recording paper. An image forming method, wherein the operation is temporarily stopped at a timing set according to a change in temperature of the developer during image formation, and a cooling period is provided. Means for forming a latent image on the image carrier, means for developing the latent image with a developer containing toner, primary transfer means for transferring the toner image formed on the image carrier to the intermediate transfer member, and toner image Means for cleaning the image carrier after transfer to the intermediate transfer body, secondary transfer means for transferring the toner image transferred and formed on the intermediate transfer body to the recording paper, means for cleaning the intermediate transfer body after transferring the toner image to the recording paper , Means for cooling the image carrier, the developer and the intermediate transfer member, the operation is temporarily stopped at a timing set by the transition of the temperature of the developer during the continuous image formation, from the image carrier, the developer and the intermediate transfer member An image forming apparatus comprising control means for cooling at least one selected.

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