JP2009237119A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, capable of suppressing temperature rise in the apparatus in double-sided printing processing in a compact apparatus, such as a printer, a copying machine, using an electrophotographic system. <P>SOLUTION: The image forming apparatus having a double-sided printing function includes: a discrimination means for discriminating whether printing processing that is being performed uses the double-sided printing function; a temperature detection means for detecting the temperature inside the apparatus; a rotational speed control means for controlling the rotational speed of a developing roll that develops an electrostatic latent image formed on a photoreceptor with developer; a first setting means for setting set first temperature; and a printing processing control means for controlling, when the discrimination means discriminates that the printing processing that is being performed uses the double-sided printing function, and also the temperature inside the apparatus detected by the temperature detection means is equal to or higher than the first temperature set by the first setting means, to stop the printing processing that is being performed, designate the rotational speed control means of low-speed rotation to control the rotational speed of the developing roll to the low-speed rotation, and restart the stopped printing processing at the low-speed rotation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In recent years, image forming apparatuses such as printing apparatuses and copiers have been miniaturized, and as a result, the mounting of various components in the apparatus becomes overcrowded, and the flow of air to waste heat generated in the apparatus As a result, it is difficult to secure heat and heat is easily generated in the apparatus.

  Even in such a situation, in an image forming apparatus that performs only single-sided printing, a sheet that has become accustomed to a temperature close to the outside temperature passes through the apparatus, so this sheet absorbs heat generated in the apparatus. It works to alleviate the temperature rise in the device.

  However, in the case of an image forming apparatus that performs double-sided printing, printing on one side is the same as on single-sided printing, but printing on the other side is for fixing an image transferred to one side. Since the sheet heated by the fixing device passes through the interior of the apparatus, the heat of the sheet increases the temperature in the apparatus.

  Since the developing unit is mounted in the apparatus, the developer in the developing unit heats itself by sliding on the layer forming member and the housing, and the temperature rises. As the temperature rises, the temperature of the developer rises excessively, and as a result, the developer may block and image quality defects may occur.

  In order to prevent this, it is necessary to reduce the heat generation of the developing unit itself or to secure the flow of air around the developing unit and exhaust the hot air around the developing unit that has become high temperature. Due to the downsizing of the device, it is difficult to secure a space for exhausting the air around the developing device, and even if space is secured, it is necessary to add a fan to exhaust the air in the device Therefore, there was a problem that the cost would be high.

In order to solve such a problem, for example, Patent Document 1 proposes an image forming apparatus capable of preventing image quality defects and image quality fluctuations due to toner density fluctuations in a high or low humidity environment.
JP 2003-122110 A

  In the above-mentioned Patent Document 1, a technique is disclosed in which the temperature and humidity are measured only before the apparatus starts a job, and the rotation speed of the developing roll is made variable according to the measurement result. There is no disclosure of a technique for dealing with changes and temperature changes corresponding to printing modes such as single-sided / double-sided.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of suppressing an increase in temperature in a double-sided printing process of a small apparatus such as a printer or a copier using an electrophotographic system.

  In order to achieve the above object, the image forming apparatus according to the first aspect of the present invention is an image forming apparatus having a double-sided printing function, and discriminating whether or not an ongoing printing process uses the double-sided printing function. Means, temperature detecting means for detecting the temperature in the apparatus, rotational speed control means for controlling the rotational speed of the developing roll for developing the electrostatic latent image formed on the photosensitive member with a developer, and a first temperature. It is determined that the first setting means for setting and the printing process being executed by the determining means uses the duplex printing function, and the internal temperature detected by the temperature detecting means is the first setting. When the temperature is equal to or higher than the first temperature set by the means, the printing process being executed is stopped, and the rotation speed control means controls the rotation speed of the developing roll to a low speed rotation, and the low speed rotation causes the Stop the printing process Characterized by comprising a printing control means for opening.

  According to a second aspect of the present invention, in the first aspect of the invention, the second setting means for setting a second temperature lower than the first temperature is provided, and the print processing control means is configured to perform the low-speed rotation. When the temperature inside the apparatus detected by the temperature detection means is equal to or lower than the second temperature set by the second setting means in the printing process, the printing process being executed is stopped and the rotational speed is stopped. The rotation speed of the developing roll is returned to high-speed rotation by the control means, and the stopped printing process is restarted at the high-speed rotation.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the adjustment image forming means for forming a reference image for density adjustment on the photoconductor in a state where the developing roll is rotated at a low speed, and the adjustment A density detecting means for detecting the density of the reference image formed by the image forming means; a converting means for converting the density detected by the density detecting means into a density in a state where the developing roll is rotated at a low speed; and the developing When the roll is rotated at a low speed, the density of the printing process is adjusted based on the density detected by the density detecting unit, and when the developing roll is rotated at a high speed, the printing is performed based on the density converted by the converting unit. And a density adjusting means for adjusting the density of the processing.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus having a double-sided printing function, wherein a discrimination means for discriminating whether an ongoing printing process uses the double-sided printing function, and an internal temperature of the apparatus are detected. A temperature detecting unit, a rotation speed of a developing roll that develops the electrostatic latent image formed on the photosensitive member with a developer, and a sheet conveying unit that conveys a sheet onto which the developer image developed by the developing roll is transferred. A speed control unit that controls the conveyance speed, a first setting unit that sets a first temperature, and a printing process that is being executed by the determination unit is determined to use the duplex printing function, and the temperature When the temperature inside the apparatus detected by the detecting means becomes equal to or higher than the first temperature set by the first setting means, the printing process being executed is stopped, and the speed control means causes the developing roll to move. Rotation speed The sheet conveying speed of the fine said sheet conveyance means is controlled to a low speed, characterized by comprising a printing control means for resuming the print processing the stop in the slow.

  The invention of claim 5 comprises the second setting means for setting a second temperature lower than the first temperature in the invention of claim 4, wherein the print processing control means When the temperature in the apparatus detected by the temperature detection means is equal to or lower than the second temperature set by the second setting means by the printing process, the printing process being executed is stopped and the speed control means Thus, the rotational speed of the developing roll and the paper transport speed of the paper transport means are returned to a high speed, and the stopped printing process is restarted at the high speed.

  According to a sixth aspect of the present invention, in the fourth or fifth aspect of the present invention, the adjustment image forming means for forming a reference image for density adjustment on the photoconductor with the developing roll rotated at a low speed, and the adjustment A density detecting means for detecting the density of the reference image formed by the image forming means; a converting means for converting the density detected by the density detecting means into a density in a state where the developing roll is rotated at a low speed; and the developing When the roll is rotated at a low speed, the density of the printing process is adjusted based on the density detected by the density detecting unit, and when the developing roll is rotated at a high speed, the printing is performed based on the density converted by the converting unit. And a density adjusting means for adjusting the density of the processing.

  According to the first aspect of the present invention, it is possible to suppress an increase in temperature in the apparatus in duplex printing without newly adding an apparatus such as a cooling fan.

  According to the second aspect of the present invention, high-speed printing processing can be realized without causing image deterioration due to temperature change in the apparatus for images formed by double-sided printing.

  According to the third aspect of the present invention, it is possible to prevent image deterioration associated with a temperature change in the apparatus of an image formed by double-sided printing.

  According to the fourth to sixth aspects of the present invention, it is possible to suppress the temperature rise in the apparatus corresponding to the temperature change in the apparatus in double-sided printing.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram showing a configuration of a main part of an image forming apparatus 1 according to the present invention.

  As shown in FIG. 1, the image forming apparatus 1 includes a control unit 10, a developing device control unit 11, an exposure device 12, a developing device 20, a photosensitive drum 30, an intermediate transfer body unit 60, and a fixing device. 70, a paper transport mechanism (a portion surrounded by a broken line) 80, and a paper storage unit 90.

  The control unit 10 is a CPU (= Central Processing Unit) that controls each part of the image forming apparatus 1 and performs overall control of the entire image forming apparatus 1.

  The developing device control unit 11 performs overall control of the entire developing device 20, and also includes a developing device (Y) 21, a developing device (M) 22, a developing device (C) 23, and a developing device (K) mounted on the developing device 20. The drive control of the developing roll 211 which each 24 comprises later is performed.

  Specifically, the drive control of the developing roll 211 is performed based on the temperature detected by the temperature sensor 40 disposed in the vicinity of the developing device 20 in order to prevent image deterioration due to heat generation of each developing device. Control to adjust the rotation speed.

  The exposure device 12 controls the laser light applied to the surface of the photosensitive drum 30 and controls the exposure so that an electrostatic latent image corresponding to the image to be formed is formed on the surface of the photosensitive drum 30. I do.

  The photosensitive drum 30 is rotationally driven at a predetermined rotational speed in a direction indicated by an arrow (counterclockwise) in the drawing by a driving means (not shown). The surface of the photosensitive drum 30 is charged by a charging roll 31. After being uniformly charged to a predetermined potential, exposure is performed with a laser beam controlled in accordance with an image to be formed by an exposure device 12 such as ROS (= Raster Output Scanner).

  In the case of forming a full-color image, the photosensitive member is controlled by laser light controlled based on the image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) of the image to be formed. The surface of the drum 30 is sequentially exposed, and an electrostatic latent image corresponding to each color is formed on the surface of the photosensitive drum 30.

  The electrostatic latent images corresponding to the respective colors formed on the surface of the photosensitive drum 30 are yellow (Y), magenta (M), cyan (C), and black (K) included in the rotary developing device 20. Development is performed by the developing unit (Y) 21, the developing unit (M) 22, the developing unit (C) 23, and the developing unit (K) 24 filled with toner corresponding to each color, and a toner image of a predetermined color is exposed to light. Formed on the surface of body drum 30.

  Specifically, the development of a full-color image by the rotary developing device 20 is applicable by rotating the rotary developing device 20 in the direction of the arrow (clockwise) in the drawing by a motor (not shown) of the rotary developing device 20. The color developing unit (Y) 21, the developing unit (M) 22, the developing unit (C) 23, and the developing unit (K) 24 are aligned with the developing position facing the photosensitive drum 30, thereby developing each developing unit. The electrostatic latent images formed on the surface of the photosensitive drum 30 by the devices 21, 22, 23, and 24 are respectively yellow (Y), magenta (M), cyan (C), and black (K) toners. develop.

  A density sensor 50 that can detect the density of an image developed with toner of each color on the surface of the photosensitive drum 30 is disposed at a predetermined position above the surface of the photosensitive drum 30. 50, the image density of the patch image for adjusting the image density (reference image) formed on the surface of the photosensitive drum 30 is detected when the rotation speed of a developing roll (to be described later) of the rotary developing device 20 is changed. It is configured.

  The density sensor 50 is of a reflective type, and is configured to output an electric signal corresponding to the density value by irradiating the surface of the photosensitive drum 30 with light and detecting the reflected light. Yes.

  The toner images of each color developed on the surface of the photosensitive drum 30 are sequentially transferred onto an intermediate transfer belt 62 of an intermediate transfer member by a primary transfer roll 61 of the intermediate transfer unit 60, and four colors (Y, M, C, K) toner images are formed on the intermediate transfer belt 62 so as to overlap each other.

  The intermediate transfer belt 62 is rotatably stretched by a drive roll 64, an idle roll 65, a backup roll 66, and an idle roll 67. The drive roll 64 has excellent constant speed (not shown). The intermediate transfer belt 62 is driven by a drive motor to rotate at a predetermined speed.

  When the transfer of the four color toner images from the photosensitive drum 30 onto the intermediate transfer belt 62 is completed, the residual toner on the surface of the photosensitive drum 30 is removed from the photosensitive drum 30 by a cleaning device 32 including a cleaning blade. Then, the next developing operation is waited.

  The four color toner images transferred onto the intermediate transfer belt 62 in a multiplexed manner are conveyed from the sheet storage unit 90 by the sheet conveying mechanism 80 by the secondary transfer roll 63 that is in pressure contact with the backup roll 66 via the intermediate transfer belt 62. It is collectively transferred onto the incoming paper P (front surface).

  Specifically, the paper P is fed by a paper feed roll 81 of a paper transport mechanism 80 from a paper feed cassette of a paper storage unit 90 provided in the lower part of the main body of the image forming apparatus 1, and a plurality of transport roll pairs 82 are supplied. -1, 82-2, 82-3, and conveyed to the resist roll pair 83.

  The sheet P conveyed to the registration roll pair 83 is temporarily stopped there, and then rotated with the backup roll 66 by the registration roll pair 83 that starts rotating in synchronization with the toner image transferred onto the intermediate transfer belt 62. The secondary transfer roll 63 is conveyed via the intermediate transfer belt 62 to a secondary transfer position where they are pressed against each other, and the four color toner images formed on the intermediate transfer belt 62 at this secondary transfer position are collectively displayed. Transferred onto the paper P.

  When the transfer of the four-color toner images transferred onto the intermediate transfer belt 62 onto the paper P is completed, the intermediate transfer belt 62 receives residual toner on the intermediate transfer belt 62 by the belt cleaner 33 facing the idle roll 65. It is removed and the next transfer operation is waited.

  The waste toner scraped off from the photosensitive drum 30 by the cleaning device 32 is collected in a waste toner collection container 34, and the waste toner removed by the belt cleaner 33 is transferred to an auger or a transport pipe (not shown). The toner is conveyed to the waste toner collecting container 34 and collected by a conveying means such as a screw.

  The paper P on which the four color toner images are transferred is conveyed to the fixing device 70, and the four color toner images transferred onto the paper P are heated and pressed by the heating roll 71 and the pressure roll 72 of the fixing device 7. And fixed on the paper P.

  When the printing process is a single-sided printing process, the sheet P on which the four-color toner images are fixed is discharged to the discharge tray 91 on the side surface of the main body of the image forming apparatus 1 through the pair of conveying rolls 82-4. When the printing process is a duplex printing process, a drive roll pair 84 and a plurality of transport roll pairs 82-5, 82-6, 82-7, 82-8 and a plurality of transport roll pairs 82 are transferred by a transport switching device (not shown). -2 and 82-3 to the registration roll pair 83, and after the image formation on the back surface of the paper P is performed according to the operation procedure described above, it is discharged to the discharge tray 91.

  FIG. 2 is a configuration diagram illustrating an example of a configuration of a main part of the rotary developing device 20.

  As shown in FIG. 2, the rotary developing device 20 includes a rotating body (not shown) that can rotate clockwise around a rotating shaft 200 located in the center. Is formed of a central portion formed in a substantially square shape and four arms extending from the central portion in a substantially radial direction so as to form an angle of 90 degrees with each other.

  The four arms of the rotating body are respectively attached to yellow (Y), magenta (M), cyan (C), and black (K) developing devices (Y) 21 (not shown) by mounting means (not shown). An arrow portion), a developing device (M) 22 (arrow portion in the drawing), a developing device (C) 23 (arrow portion in the drawing), and a developing device (K) 24 (arrow portion in the drawing) are mounted. .

  The developing unit (Y) 21, the developing unit (M) 22, the developing unit (C) 23, and the developing unit (K) 24 mounted on each of the four arms have a rotating body with a rotating shaft 200 as a center. By rotating around, each developing device also rotates clockwise around the rotation axis 200.

  These developing units are all configured in the same manner, and here, for convenience of description, the configuration of the developing unit (Y) 21 will be mainly described.

  The developing device (Y) 21 is roughly divided into a developing device main body 210 (a portion corresponding to the white frame portion of the developing device (M) 22 in the figure) and a developer cartridge 220 (a developing device (K) in the figure). 24 portions corresponding to white frame portions).

  The developing device main body 210 of the developing device (Y) 21 includes a developing roll 211 that is long in the direction perpendicular to the paper surface inside the developing device main body 210, and is located on the back side of the developing roll 211. Two spiral augers 212 and 213 extending in parallel are arranged.

  The spiral augers 212 and 213 are formed with blades so as to form a spiral around the rotation axis. When the developing roll 211 rotates, the spiral auger 213 removes the developer 221 stored in the developer cartridge 220 from the paper surface. And transport in one direction perpendicular to

  The spiral auger 212 conveys the developer 221 while stirring the developer 221 in the direction opposite to the direction in which the spiral auger 213 is conveyed, and supplies the developer 221 evenly to the developing roll 211.

  The developing roll 211 forms a magnetic brush of the developer 221 on the surface of the developing roll 211 by attracting the carrier contained in the developer 221 with a magnetic force by a magnet roll (not shown) disposed inside the developing roll 211. Then, the toner adsorbed on the carrier is transported to the developing area facing the photosensitive drum 30.

  On the other hand, the electrostatic latent image formed on the surface of the photosensitive drum 30 is visualized by a magnetic brush of a developer 221 made of carrier and toner formed on the surface of the developing roll 211.

  The developer cartridge 220 is formed of a cylindrical container that is elongated in a direction perpendicular to the paper surface. The developer cartridge 220 includes a storage chamber (not shown) for the new developer 221 and a view of the deteriorated developer 221. It is divided into a collection chamber (not shown), and a new developer storage chamber contains toner to be replenished each time the toner in the developing device main body 210 is reduced by using toner for image formation. A new carrier to be supplied to replace the deteriorated developer 221 is filled.

  Further, a supply port (not shown) is provided in the storage chamber for the new developer 221, and the supply port communicates with a substantially cylindrical casing 222 for guiding the new developer 221 to the developing device main body 210. is doing.

  The cylindrical casing 222 is disposed at the upper part on the back side of the developing device main body 210.

  A spiral auger 223 is disposed in the casing 222, and the developer 221 replenished from the developer cartridge 220 is provided on the upper surface on the back side of the developing device main body 210 by the spiral auger 223. And is supplied into the developing device main body 210.

  The spiral auger 223 is formed with blades so as to form a spiral around the rotation axis, similar to the spiral augers 212 and 213, and the development supplied from the developer cartridge 220 when the spiral auger 223 rotates. The agent 221 is conveyed while stirring in one direction perpendicular to the paper surface.

  A control operation for suppressing the temperature rise in the image forming apparatus 1 configured as described above in the double-sided printing process will be described with reference to FIG.

  FIG. 3 is a flowchart showing a control operation for suppressing the temperature rise in the apparatus in the double-sided printing process of the image forming apparatus 1.

  As illustrated in FIG. 3, when the image forming apparatus 1 receives a print job instructed to perform print processing, the image forming apparatus 1 analyzes the print job to be printed, and performs print data print processing based on the print conditions included in the print job. Start.

  In addition to the print data, the print job includes print conditions (number of copies, print type of single-sided or double-sided printing, resolution, etc.) and various information of the print request source.

  When the printing process is started, the control unit 10 of the image forming apparatus 1 determines whether the printing process is a duplex printing process or a simplex printing process. If the printing process is a simplex printing process (NO in S101). ), This control operation is terminated.

  The control unit 10 acquires and recognizes the information of the print type included in the print condition when starting the printing process, and prints the information of the acquired print type of single-sided printing or double-sided printing (not shown). The value is stored in a nonvolatile memory (not shown) provided in the image forming apparatus 1.

  If the printing process is a double-sided printing process (YES in S101), the control unit 10 acquires the temperature detected by the temperature sensor 40 provided in the vicinity of the developing device 20 in the image forming apparatus 1 ( In step S102, the temperature (in-apparatus temperature, Ta) is compared with a preset warning release temperature (Tb) (S103).

  In S103, when the in-apparatus temperature (Ta) is higher than the warning release temperature (Tb) (YES in S104), the in-apparatus temperature (Ta) acquired in S102 and the preset developer warning temperature ( Tc) is compared (S105).

  The warning release temperature (Tb) and the developer warning temperature (Tc) are preset by the manufacturer or user of the image forming apparatus 1 and stored in a nonvolatile memory (not shown) in the apparatus. Tb) is set at a value of 32 degrees Celsius, for example, and the developing device warning temperature (Tc) is set at a value of 48 degrees Celsius, for example.

  In S105, when the temperature in the apparatus (Ta) is higher than the developing device warning temperature (Tc) (YES in S106), the value of the developing device warning flag set in a non-illustrated nonvolatile memory in the apparatus is ON. (S107).

  This developer warning flag is set to a value indicating either ON or OFF, and is set to ON when the apparatus internal temperature (Ta) exceeds the developer warning temperature (Tc), until the value is changed. The value is stored as it is.

  In S107, when the value of the developing device warning flag is ON (YES in S107), the internal temperature (Ta) exceeds the developing device warning temperature (Tc) before this step, and each of the developing devices 21, 22, 23, Since the 24 developing rolls 211 have already been operated at a low speed, this control operation is terminated while the low speed operation is continued.

  The low-speed operation of the developing roll 211 referred to here is the development of each developing device (Y) 21, developing device (M) 22, developing device (C) 23, and developing device (K) 24 mounted on the developing device 20. The rotation speed of the roll 211 is rotated at a lower speed than the normal rotation speed. The normal rotation speed means that the apparatus internal temperature (Ta) does not exceed the developing device warning temperature (Tc) and is in a normal state. This is the rotation speed of the developing roll 211 when the image forming apparatus 1 performs the printing process.

  Further, the image forming apparatus 1 rotates the rotation speed of the photosensitive drum 30 in synchronization with the change in the rotation speed of the developing roller 211 so that the relative speed of the developing roller 211 with respect to the photosensitive drum 30 does not change. It is configured.

  Further, since the value of the developing device warning flag is stored in the nonvolatile memory, even if the power of the image forming apparatus 1 is shut off while the value of the developing device warning flag is ON, the value remains unchanged. When it is stored and power is supplied next time, the value of the developing device warning flag is ON.

  In S107, if the value of the developer warning flag is not ON (NO in S107), the value of the developer warning flag that has been set to OFF is set to ON (S108), and the duplex printing currently being processed is performed. Processing is interrupted (S109).

  The interruption of the double-sided printing process currently being processed is performed by each unit including the paper transport mechanism 80 related to the double-sided printing process received from the control unit 10 and a control operation corresponding to the instruction is received. By doing so, the double-sided printing process is interrupted.

  When the duplex printing process is interrupted, the control unit 10 instructs the developing device control unit 11 to operate the developing roll 211 at a low speed. Based on this instruction, the developing device control unit 11 implements each of the developing devices 20. Control is performed so that the rotation speed of the developing roller 211 of the developing device (Y) 21, the developing device (M) 22, the developing device (C) 23, and the developing device (K) 24 is rotated at a lower speed than the normal rotating speed. The mode is changed to the control mode (hereinafter referred to as “low speed operation mode”) (S110).

  When the control mode of the developing device controller 11 is changed to the low speed operation mode, the image density is adjusted in the low speed operation of the developing roll 211 of each developing device (S111).

  The image density is adjusted here because the developing roller 211 rotates at a low speed, and the developing amount in this state is lower than the developing amount before the low-speed rotation, and the image density is lowered. To do.

The image density is adjusted by determining whether or not the amount of toner supplied in the low-speed operation of the developing roll 211 is appropriate, and adjusting the developing bias and the exposure amount so that the toner density becomes an appropriate value. It is.

Specifically, the developing roller 211 of each developing device of the developing device 20 is rotated at a low speed based on the control of the low speed operation mode of the developing device control unit 11 while the paper P is not conveyed, and in this state, the photosensitive drum 30 A patch image for image density adjustment is formed on the surface, the toner density of the patch image is detected by the density sensor 50, and the development bias and the exposure amount are changed so that the detected toner density becomes an appropriate value. Adjust.

  When adjusting the image density by changing the exposure amount, the control unit 10 does not show the amount of emitted light that can obtain an optimum toner density based on the toner density of the image density adjustment patch image detected by the density sensor 50. The exposure apparatus 12 is specified based on the reference table A and instructed to expose the surface of the photosensitive drum 30 with the specified light emission quantity.

  In the reference table A described above, each value of the amount of emitted light that provides an optimum toner density corresponding to the detected toner density is managed in association with each other, and these values are acquired in advance and created as the reference table A. And stored in a non-volatile memory.

  When the image density is adjusted by changing the development bias, the control unit 10 sets a development bias voltage that can obtain an optimum toner density based on the toner density of the patch image for image density adjustment detected by the density sensor 50. Development is performed based on a reference table B (not shown) and applied to each developing device (Y) 21, developing device (M) 22, developing device (C) 23, and developing device (K) 24. Instructs the device control unit 11.

  When the image density is adjusted to the optimum image density by adjusting the image density in S111, the double-sided printing process interrupted in S109 is resumed, and this control operation is terminated.

  In S103, when the internal temperature (Ta) is lower than the warning release temperature (Tb) (NO in S104), the value of the developer warning flag is confirmed (S114), and the value of the developer warning flag is set. If it is not ON (NO in S114), since the apparatus internal temperature (Ta) is lower than the developing device warning temperature (Tc) before this step, the developing roll 211 of each developing device has already been operated at high speed. Therefore, the present control operation is terminated while the high speed operation is continued (S115).

  The high-speed operation of the developing device 20 here means that the image forming apparatus 1 performs the printing process in a normal state where the internal temperature (Ta) of the image forming apparatus 1 does not exceed the developing device warning temperature (Tc). The developing roll 211 of each developing device (Y) 21, developing device (M) 22, developing device (C) 23, and developing device (K) 24 is rotated at a normal rotation speed.

  In S114, when the value of the developing device warning flag is ON (YES in S114), the internal temperature (Ta) exceeds the developing device warning temperature (Tc) before this step, and the developing roll 211 of each developing device has already been set. Since it is in a high-speed operation state, the value of the developing device warning flag is set to OFF and changed (S115), and then the duplex printing process currently being processed is interrupted (S116).

Note that when the value of the developing device warning flag in S114 is ON, it indicates that the temperature inside the apparatus exceeding the developing device warning temperature (Tc) has cooled and becomes lower than the warning release temperature (Tb).
When the double-sided printing process is interrupted, the rotation speed of the developing roll 211 of each developing device is switched to a high speed operation (S117), and the image density is adjusted in the high speed operation of each developing roll 211 (S118).

  In this adjustment of the image density, by increasing the rotation speed of the developing roll 211, the developing amount in this state increases more than the developing amount before the developing roll 211 is rotated at high speed, and the image density is excessive. Therefore, this is done to adjust this.

  As in the case of the image density adjustment performed in S111, the image density adjustment is performed by forming a patch image for image density adjustment on the photosensitive drum 30 and detecting the patch image by the density sensor 50. The development bias and the exposure amount are changed according to the density.

  When the image density is adjusted to the optimum image density by the adjustment of the image density, the double-sided printing process interrupted in S110 is resumed, and this control operation is ended.

  The control operations in S101 to S119 described above are repeatedly performed at predetermined time intervals during the printing process in the image forming apparatus 1.

  In the description of the above embodiment, the description has been made assuming an image forming apparatus provided with a rotary developing device such as a printer, a copying machine, a facsimile or the like using an electrophotographic system, but each developing device (Y) 21, developing device ( M) 22, developing unit (C) 23 and developing unit (K) 24 are arranged side by side, and a toner image of each color is formed on each photosensitive drum corresponding to each developing unit to form an image. The present invention can also be applied to other image forming apparatuses.

  In this case, each density sensor is arranged at a predetermined position above the surface of the photosensitive drum corresponding to each developing device, and when adjusting the image density, the image density adjusting surface is adjusted on the surface of each photosensitive drum. Each patch image is formed, and each formed patch image is detected by each density sensor, and the development bias and the exposure amount are changed according to the detected density.

  Alternatively, a density sensor is disposed at a position opposite to the intermediate transfer body or the paper transport belt, and the patch image for adjusting the image density of each color is transferred to the intermediate transfer body or the paper transport belt, and then each patch image is transferred to the density sensor. It is good also as a structure which changes by developing bias and exposure amount according to detected density | concentration according to detected.

  In this case, it is not necessary to prepare a density sensor for each color even in the tandem method.

  In the above description of the embodiment, the description has been made on the assumption that the rotation speed of the developing roll of each developing device of the developing device can be controlled independently. However, the image where the rotation speed of the developing roll cannot be controlled independently. The present invention can also be applied to a forming apparatus.

1 is a configuration diagram showing a configuration of a main part of an image forming apparatus 1 according to the present invention. Configuration diagram showing an example of a configuration of a main part of the rotary developing device 20 A flowchart showing a control operation for suppressing a temperature rise in the apparatus in the double-sided printing process of the image forming apparatus 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control part 11 Developing apparatus control part 12 Exposure apparatus 20 Developing apparatus 21 Developing device (Y)
22 Developer (M)
23 Developer (C)
24 Developer (K)
DESCRIPTION OF SYMBOLS 30 Photosensitive drum 31 Charging roll 32 Cleaning apparatus 33 Belt cleaner 34 Waste toner collection container 40 Temperature sensor 50 Concentration sensor 60 Intermediate transfer body part 61 Primary transfer roll 62 Intermediate transfer belt 63 Secondary transfer roll 64 Drive roll 65, 67 Idle roll 66 Backup roll 66
DESCRIPTION OF SYMBOLS 70 Fixing device 71 Heating roll 72 Pressure roll 80 Paper conveyance mechanism 81 Paper feed roll 82-1, 82-2, 82-3, 82-4 Conveyance roll pair 82-5, 82-6, 82-7, 82- 8 transport roll pair 83 resist roll pair 84 drive roll pair 90 paper storage unit 91 discharge tray 200 rotating shaft 210 developing device main body 211 developing roll 212, 213, 223 spiral auger 220 developer cartridge 221 developer 222 casing

Claims (6)

An image forming apparatus having a duplex printing function,
Determining means for determining whether or not the printing process being executed uses the double-sided printing function;
Temperature detecting means for detecting the temperature in the apparatus;
A rotational speed control means for controlling the rotational speed of a developing roll for developing the electrostatic latent image formed on the photoreceptor with a developer;
First setting means for setting a first temperature;
It is determined that the printing process being executed by the determination unit uses the duplex printing function, and the internal temperature detected by the temperature detection unit is equal to or higher than the first temperature set by the first setting unit. In this case, the printing process being executed is stopped, the rotation speed control means controls the rotation speed of the developing roll to a low-speed rotation, and the print process is restarted at the low-speed rotation. An image forming apparatus comprising: a control unit. Second setting means for setting a second temperature lower than the first temperature,
The print processing control means includes
When the internal temperature detected by the temperature detection means is equal to or lower than the second temperature set by the second setting means by the printing process at the low speed rotation, the printing process being executed is stopped. The image forming apparatus according to claim 1, wherein the rotation speed control unit restores the rotation speed of the developing roll to a high speed rotation and restarts the stopped printing process at the high speed rotation. Adjusting image forming means for forming a reference image for density adjustment on the photoconductor in a state where the developing roll is rotated at a low speed;
Density detecting means for detecting the density of the reference image formed by the adjusted image forming means;
Conversion means for converting the density detected by the density detection means into a density in a state where the developing roll is rotated at a low speed;
In the state where the developing roll is rotated at a low speed, the density adjustment of the printing process is performed based on the density detected by the density detecting unit, and in the state where the developing roll is rotated at a high speed, based on the density converted by the converting unit. The image forming apparatus according to claim 1, further comprising: a density adjusting unit that performs density adjustment of the printing process. An image forming apparatus having a duplex printing function,
Determining means for determining whether or not the printing process being executed uses the double-sided printing function;
Temperature detecting means for detecting the temperature in the apparatus;
Controls the rotation speed of a developing roll that develops the electrostatic latent image formed on the photoreceptor with a developer, and the conveyance speed of a sheet conveying means that conveys the sheet onto which the developer image developed by the developing roll is transferred. Speed control means;
First setting means for setting a first temperature;
It is determined that the printing process being executed by the determination unit uses the duplex printing function, and the internal temperature detected by the temperature detection unit is equal to or higher than the first temperature set by the first setting unit. In this case, the printing process being executed is stopped, the rotational speed of the developing roll and the paper transport speed of the paper transport means are controlled to low speed by the speed control means, and the stopped printing is performed at the low speed. An image forming apparatus comprising: a print processing control unit that resumes processing. Second setting means for setting a second temperature lower than the first temperature,
The print processing control means includes
When the temperature inside the apparatus detected by the temperature detecting unit by the low-speed printing process is equal to or lower than the second temperature set by the second setting unit, the printing process being executed is stopped, The image forming apparatus according to claim 4, wherein the rotation speed of the developing roller and the paper conveyance speed of the paper conveyance unit are returned to high speed by the speed control unit, and the stopped printing process is resumed at the high speed. Adjusting image forming means for forming a reference image for density adjustment on the photoconductor in a state where the developing roll is rotated at a low speed;
Density detecting means for detecting the density of the reference image formed by the adjusted image forming means;
Conversion means for converting the density detected by the density detection means into a density in a state where the developing roll is rotated at a low speed;
In the state where the developing roll is rotated at a low speed, the density adjustment of the printing process is performed based on the density detected by the density detecting unit, and in the state where the developing roll is rotated at a high speed, based on the density converted by the converting unit. The image forming apparatus according to claim 4, further comprising: a density adjusting unit that performs density adjustment of the printing process.

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