JP2006145817A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus preventing the deterioration of image quality resulting from the occurrence of uneven electrification by suppressing the occurrence of insulation of the grid of a scorotron as an electrifying apparatus due to an air flow for removing ozone and nitrogen oxide (NOx) generated by the corona discharge of the electrifying apparatus. <P>SOLUTION: Regarding the image forming apparatus for forming an image by using at least the electrifying apparatus, and provided with an air flow forming means for forming the air flow arranged near the electrifying apparatus, the image forming apparatus is provided with a detecting means for detecting an environmental condition where the image forming apparatus is installed, and a control means for controlling the operating state of the air flow means so as to be stopped or reduced in accordance with the detection value of the detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention employs an electrophotographic method, an electrostatic recording method, an ionography method, or the like to form a latent image on the image carrier due to a difference in electrostatic potential and transfer toner to the latent image. The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image by forming a visual image, and more specifically, an image having a charging device that uniformly charges the surface of an image carrier using corona discharge. The present invention relates to a forming apparatus.

JP 2001-109359 A JP 2002-40876 A JP 2003-140533 A JP-A-6-3901

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer that employs this type of electrophotographic system, electrostatic recording system, or ionography system, the surface of an image carrier such as a photosensitive drum is predetermined by a charging device. After uniformly charging the potential, the surface of the image carrier is subjected to image exposure, or an electric charge is applied according to the image information, whereby an electrostatic latent image corresponding to the image information is formed on the surface of the image carrier. The image is formed by transferring the toner to the electrostatic latent image and making it visible.

  At this time, as a charging device for uniformly charging the surface of the image carrier such as the photosensitive drum, the surface of the image carrier is uniformly charged to a predetermined potential using charges generated by corona discharge. The scorotron configured as described above is often used in an image forming apparatus with particularly high productivity.

  In an image forming apparatus using a charging device such as the above scorotron, it is known that image density unevenness occurs due to partial contamination of a discharge wire of the charging device or partial deterioration of an image carrier such as a photosensitive drum. It has been. Therefore, the image forming apparatus includes a cleaning member that cleans the discharge wire of the charging device, and a service engineer periodically cleans the discharge wire of the charging device.

  In addition, since the charging device such as the above scorotron charges the surface of the image carrier uniformly using the charges generated by the corona discharge, ozone, nitrogen oxide (NOx), etc. are associated with the corona discharge. If these ozone and nitrogen oxide (NOx) are left as they are, the surface of the image carrier such as the photosensitive drum in the vicinity of the charging device deteriorates, and the image quality such as image density unevenness is deteriorated. It will cause deterioration.

  Therefore, in a conventional image forming apparatus such as a copying machine or a printer using a charging device such as the scorotron, an intake means for sucking external air is provided in the vicinity of the charging device or the photosensitive drum. The system is configured to treat residual ozone and nitrogen oxides (NOx) by providing an air flow by providing an air intake means for exhausting air in the vicinity of the photosensitive drum to the outside.

  However, the conventional technique has the following problems. That is, in the case of an image forming apparatus such as the above-mentioned conventional copying machine or printer, ozone, nitrogen oxide (NOx), etc. generated by corona discharge of a charging device such as a scorotron and remaining in the vicinity of the charging device, Residual ozone and nitrogen oxides (NOx) are treated by generating an air flow in the vicinity of the charging device and the photosensitive drum.

  For this reason, in the conventional image forming apparatus such as a copying machine or a printer, an air flow generated in the vicinity of the charging device or the photosensitive drum when the image bearing member such as the photosensitive drum is charged by the charging device during image formation. As a result, the inventors of the present invention have revealed that the insulation of the scorotron grid as a charging device is presumed to be caused by an oxidation reaction of silica or the like.

  As described above, in the conventional image forming apparatus such as a copying machine and a printer, silica or the like is originally applied to the scorotron grid by the air flow for removing ozone and nitrogen oxide (NOx) remaining in the vicinity of the charging device. It has been found that insulation, which is estimated to be caused by the oxidation reaction, occurs, and if the insulation pattern of the grid is uneven, charging unevenness is caused and the image quality is adversely affected. It was. In addition, the charging unevenness caused by the insulation of the grid of the scorotron and the adverse effect on the image quality are noticeably generated in a low-humidity environment where the humidity is low as an environmental condition, and in a high-humidity environment where the humidity is relatively high, It turned out that it hardly occurred. This is because, in a high humidity environment where the humidity is relatively high, the resistance of the grid of the scorotron that is insulated due to the influence of humidity or the like is reduced, so that charging unevenness is unlikely to occur and the adverse effect on the image quality is suppressed. it is conceivable that.

  As prior arts related to the above problems, those disclosed in JP 2001-109359 A, JP 2002-40876 A, JP 2003-140533 A, JP 6-3901 A, etc. It has already been proposed.

  In the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2001-109359, the gas and moisture generated by charging are adsorbed to the lubricant applied to the surface of the photoreceptor, and as a result, the surface resistance of the photoreceptor is reduced. In order to prevent the occurrence of image blur, a heater for preventing moisture from adsorbing to the photosensitive drum is provided, or an intake fan provided at the intake port of the exterior of the apparatus main body is connected to the outside air. It is configured to be driven when the humidity is lower than in the apparatus main body.

  However, in the case of the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2001-109359, when the outside air humidity is lower than the inside of the apparatus main body, the intake fan provided at the intake port of the exterior portion of the apparatus main body is used. When driven, it warps and promotes insulation of the scorotron grid, which has the adverse effect.

  Further, in the case of the image forming apparatus disclosed in the above Japanese Patent Laid-Open No. 2002-40876, similarly to the above Japanese Patent Laid-Open No. 2001-109359, the ambient atmosphere temperature and humidity are detected, and the temperature and humidity detection results are detected. Therefore, the drum heater of the photosensitive drum is operated, but there is a problem that it is impossible to prevent the deterioration of the image quality due to the insulation of the scorotron grid.

  Further, in the case of the image forming apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2003-140533, an electrostatic latent image is created by exposing an image carrier that is sealed inside, and this electrostatic latent image is A printer engine for developing an image by developing with toner; a cooling device for cooling the surface of the image carrier from the inside; and a drying device for drying the surface of the image carrier from the outside of the image carrier. However, if the surface of the image carrier is dried by a drying device, the humidity around the charging device disposed in the vicinity of the image carrier is lowered, and as described above. On the other hand, the scorotron grid was insulatively insulated, and had the problem of adverse effects.

  Further, in the case of the image forming apparatus disclosed in the above Japanese Patent Laid-Open No. 6-3901, environmental condition detecting means for detecting an environmental condition under the environment in which the image forming apparatus is disposed, and this environmental condition detecting means The exposure position changing means for moving the exposure position of the photosensitive member by the exposure apparatus based on the output signal is provided, but it is still effective to some extent for stabilizing the image quality in a high humidity environment. However, there is a problem that the image quality is not reduced in a low humidity environment.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and its object is to remove ozone and nitrogen oxide (NOx) generated by corona discharge of the charging device. It is an object of the present invention to provide an image forming apparatus capable of suppressing the generation of insulation in the grid of the scorotron as a charging device by the air flow and preventing the image quality from being deteriorated due to the occurrence of charging unevenness.

  Another object of the present invention is to suppress image density unevenness by suppressing deterioration of an image carrier such as a photosensitive drum caused by ozone or nitrogen oxide (NOx) generated by corona discharge of a charging device. Insulation is generated in the grid of the scorotron as the charging device by the air flow for removing ozone and nitrogen oxide (NOx) generated by the corona discharge of the charging device while preventing the image quality deterioration such as An object of the present invention is to provide an image forming apparatus capable of suppressing image quality deterioration due to occurrence of charging unevenness.

In order to achieve the above object, the invention described in claim 1 is an image forming apparatus that forms an image using at least a charging device, and includes an airflow forming unit that forms an airflow in the vicinity of the charging device. In the provided image forming apparatus,
Detection means for detecting an environmental condition in which the image forming apparatus is installed, and control means for controlling the operation state of the airflow formation means to be stopped or reduced according to a detection value of the detection means. An image forming apparatus characterized by the above.

  As the image forming apparatus, for example, an electrophotographic method is employed, and the surface of an image carrier such as a photosensitive drum is charged by a charging device and then subjected to image exposure to form an image. However, the present invention is not limited to this, and at least an image forming apparatus that forms an image using a charging device may form an image using another method such as an electrostatic recording method or an ionography method. But of course.

  Further, in the invention described in claim 2, when the humidity as the environmental condition is low, the control of the operating state of the air flow forming means stops or reduces the air flow forming means, 2. The image forming apparatus according to claim 1, wherein the airflow forming means is operated when the humidity of the airflow is high.

  Furthermore, in the invention described in claim 3, the operation timing of the airflow forming unit is linked to the charging timing of the charging device, and only according to the detection value of the detecting unit during charging of the charging device. 3. The image forming apparatus according to claim 1, wherein control is performed.

  According to a fourth aspect of the present invention, the airflow forming means includes an intake duct that guides air to a back surface of the charging device, an intake fan that sucks outside air into the intake duct, and the charging device. 4. An exhaust duct that guides air from the opening to the outside of the machine and an exhaust fan that exhausts air to the outside of the machine through the exhaust duct. The image forming apparatus described.

  Furthermore, the invention described in claim 5 is provided with a humidifier that supplies high-humidity air to the charging device, and the humidifier is operated when the humidity is low. The image forming apparatus described in the above.

The invention described in claim 6 is an image forming apparatus that forms an image using at least a charging device, and forms an air flow in the vicinity of the charging device. In the image forming apparatus provided with the airflow forming means,
An image forming apparatus comprising: a timer built in the apparatus; and a control unit that controls the operation state of the airflow forming unit to be stopped or reduced according to a calendar function of the timer. is there.

  According to the present invention, it is possible to suppress the generation of insulation in the grid of the scorotron as the charging device by the air flow for removing ozone and nitrogen oxide (NOx) generated by the corona discharge of the charging device. It is possible to provide an image forming apparatus capable of preventing deterioration in image quality due to occurrence of unevenness.

  In addition, according to the present invention, image quality deterioration such as image density unevenness is suppressed by suppressing deterioration of an image carrier such as a photosensitive drum caused by ozone or nitrogen oxide (NOx) generated by corona discharge of a charging device. While preventing the generation of insulation in the grid of the scorotron as the charging device by the air flow for removing ozone and nitrogen oxide (NOx) generated by the corona discharge of the charging device. Therefore, it is possible to provide an image forming apparatus capable of preventing a deterioration in image quality due to occurrence of the above.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 is a block diagram showing a digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 2, this digital color copying machine is provided with an automatic document feeder (ADF) 2 that automatically feeds a document (not shown) separated one by one at the top of the copying machine main body 1. The automatic document feeder 2 also functions as a platen cover that presses the document placed on the platen glass 3. A document automatically conveyed onto the platen glass 3 by the automatic document conveying device 2 or a document placed on the platen glass 3 is read by the document reading device 4 disposed in the upper part of the copying machine main body 1. It is read and once converted into image data. The document reader 4 is reflected by an illumination lamp 5 that illuminates a document (not shown) placed on the platen glass 3, a half-rate mirror 6 that reflects a reflected light image from the document, and the half-rate mirror 6. The full-rate mirrors 7 and 8 that reflect the reflected light image of the original document to the imaging lens 9, and the optical image of the original document reflected by the full-rate mirrors 7 and 8 are reduced and irradiated to the image reading element 10 including a CCD or the like. And an image reading element 10 composed of a CCD or the like that reads an optical image of a document and converts it into an electrical signal.

  In the digital color copying machine, color image information of a color document read by the document reading device 4 is input to the image processing device 11, and the image processing device 11 performs shading correction and position shift correction as necessary. Predetermined image processing such as brightness / color space conversion, gamma correction, frame deletion, color / moving editing, and the like is performed. The digital color copying machine is also configured to function as a printer, and color image information sent from a host computer such as a personal computer (not shown) is also input to the image processing apparatus 11 of the copying machine. It is configured to be.

  The image data subjected to the predetermined image processing by the image processing apparatus 11 as described above is four colors of yellow (Y), magenta (M), cyan (C), and black (BK) (8 bits each). The material tone data is sent to a ROS 12 (Raster Output Scanner), and the ROS 12 sequentially performs image exposure with laser light according to the color material tone data.

  An image forming means 13 capable of forming a plurality of toner images having different colors is disposed inside the digital color copying machine main body 1. The image forming unit 13 mainly includes a photosensitive drum 14 as an image carrier on which an electrostatic latent image is formed, and a scorotron as a charging device that uniformly charges the surface of the photosensitive drum 14 to a predetermined potential. 15, ROS 12 as image exposure means for performing image exposure on the surface of the photosensitive drum 14, and electrostatic latent images formed on the photosensitive drum 14 are successively developed with different color toners, It is composed of a rotary developing device 16 as developing means capable of forming a plurality of toner images having different colors on the photosensitive drum 14.

  As shown in FIG. 2, the ROS 12 modulates a semiconductor laser (not shown) according to the color material gradation data, and emits a laser beam LB from the semiconductor laser according to the gradation data. The laser beam LB emitted from the semiconductor laser is deflected and scanned by the rotary polygon mirror 17 and is scanned and exposed on the photosensitive drum 14 as an image carrier through the f · θ lens 18 and the reflection mirror 19.

  The photosensitive drum 14 on which the laser beam LB is scanned and exposed by the ROS 12 is driven to rotate at a predetermined speed in the direction of the arrow by a driving unit (not shown). The surface of the photosensitive drum 14 is charged in advance with a predetermined polarity (for example, a negative polarity) and a potential by a scorotron 15 as a charging device for primary charging, and then laser light LB according to color material gradation data. Is subjected to scanning exposure to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 14 includes four color developing devices 16Y, 16M, 16C, and 16BK of yellow (Y), magenta (M), cyan (C), and black (BK). The rotary developing device 16 reversely develops, for example, a toner (charged color material) charged to a negative polarity that is the same polarity as the charged polarity of the photosensitive drum 14 to form a toner image of a predetermined color. In each of the developing devices 16Y, 16M, 16C, and 16BK of the rotary type developing device 16, for example, spherical toner having an average particle size of 5.5 μm is used. The toner image formed on the photosensitive drum 14 is charged with a negative polarity by the pre-transfer charger 20 as necessary, and the amount of charge is adjusted.

  In the digital color copying machine, for example, when a full color image is formed, every time the photosensitive drum 14 rotates, yellow (Y), magenta (M), cyan (C), black (BK). Toner images of each color of yellow (Y), magenta (M), cyan (C), and black (BK), which are sequentially exposed and developed on the photosensitive drum 14, are described later. As described above, primary transfer is performed on the intermediate transfer belt 21 while being superimposed on each other.

  The toner images of the respective colors formed on the photosensitive drum 14 are transferred onto a primary transfer roll 22 as a first transfer unit on an intermediate transfer belt 21 as an intermediate transfer member disposed below the photosensitive drum 14. Are transcribed in multiples. The intermediate transfer belt 21 has a peripheral speed of the photosensitive drum 14 by a drive roll 23, a tension roll 24, a backup roll 25 as a counter roll constituting a part of the secondary transfer means, and driven rolls 26a, 26b, and 26c. Is supported so as to be rotatable along the direction of the arrow at the same moving speed.

  On the intermediate transfer belt 21, four colors of yellow (Y), magenta (M), cyan (C), and black (BK) are formed on the photosensitive drum 14 according to the color of the image to be formed. All or part of the toner image is transferred in a state of being sequentially superimposed by the primary transfer roll 22. The toner image transferred onto the intermediate transfer belt 21 is recorded on a recording paper 27 as a recording medium conveyed to a secondary transfer position at a predetermined timing, and a backup roll 25 that supports the intermediate transfer belt 21, Transfer is performed by the pressure contact force and electrostatic attraction force of the secondary transfer roll 28 that constitutes a part of the second transfer unit that is in pressure contact with the backup roll 25. As shown in FIG. 2, the recording paper 27 has a predetermined size from a plurality of paper feeding cassettes 29, 30, 31, 32 arranged in the lower part of the digital color copying machine main body 1 by a feed roll 32. Paper is fed. The fed recording paper 27 is transported to the secondary transfer position of the intermediate transfer belt 21 by a plurality of transport rolls 33 and registration rolls 34 at a predetermined timing. Then, as described above, the toner image of a predetermined color is collectively collected on the recording paper 27 from the intermediate transfer belt 21 by the backup roll 25 and the secondary transfer roll 28 as secondary transfer means. It is designed to be transcribed.

  The recording paper 27 onto which the toner image of a predetermined color has been transferred from the intermediate transfer belt 21 is separated from the intermediate transfer belt 21 and then conveyed to the fixing device 36 by the conveying belt 35. As a result, the toner image is fixed on the recording paper 27 by heat and pressure, and in the case of single-sided copying, it is discharged as it is onto the discharge tray 38 outside the apparatus by the discharge roll 37 to complete the color image forming process.

  On the other hand, in the case of double-sided copying, the recording paper 27 on which the color image is formed on the first surface (front surface) is not discharged out of the apparatus as it is, but the conveying direction is changed downward by a reversing gate (not shown). By the roll 39 and the reverse roll 40, it is once conveyed to the reverse passage 41. Then, the recording paper 27 is conveyed to the double-sided passage 42 by the reversing roll 40 which is reversed this time, and is temporarily conveyed to the registration roll 34 by the conveying roll 43 provided in the double-sided passage 42 and stopped. The recording paper 27 is started to be conveyed again by the registration roll 34 in synchronization with the toner image on the intermediate transfer belt 21, and the toner image transfer / fixing process with respect to the second surface (back surface) of the recording paper 27. After being carried out, it is discharged outside the machine.

  In FIG. 2, 44 is a cleaning device for removing residual toner, paper dust and the like from the surface of the photosensitive drum 14 after the transfer process is completed, and 45 is a surface of the photosensitive drum 14 before the cleaning process. A pre-cleaning corotron 46 for removing static electricity and a manual feed tray are respectively shown.

  By the way, the digital color copying machine according to this embodiment is an image forming apparatus that forms an image using at least a charging device, and includes an airflow forming unit that forms an airflow in the vicinity of the charging device. In the forming apparatus, a detecting means for detecting an environmental condition in which the image forming apparatus is installed, and a control means for controlling the operation state of the airflow forming means to be stopped or reduced according to a detection value of the detecting means. It is comprised so that.

  Further, in this embodiment, the control of the operating state of the air flow forming means is performed by stopping or reducing the air flow forming means when the humidity as the environmental condition is low, and increasing the humidity as the environmental condition. In the case of humidity, the air flow forming means is configured to operate.

  Further, in this embodiment, the operation timing of the airflow forming means is linked to the charging timing of the charging device, and the control according to the detection value of the detecting means is performed only during charging of the charging device. It is configured.

  Further, in this embodiment, the air flow forming means includes an intake duct that guides air to the back surface of the charging device, an intake fan that sucks outside air into the intake duct, and an opening portion of the charging device. An exhaust duct that guides air to the outside and an exhaust fan that exhausts air to the outside of the machine through the exhaust duct.

  That is, in the digital color copying machine according to this embodiment, as shown in FIG. 3, a scorotron using corona discharge is used as a charging device for uniformly charging the surface of the photosensitive drum 14. This scorotron is excellent in the charging property of the surface of the photosensitive drum 14, and is suitable for a high-speed image forming apparatus with a high rotational speed (process speed) of the photosensitive drum 14 and high productivity. Further, the charging device 15 made of the scorotron uses corona discharge to uniformly charge the surface of the photosensitive drum 14, and therefore discharge of ozone, nitrogen oxide (NOx), etc. accompanying the corona discharge. Product is produced and released.

  As shown in FIGS. 3 and 4, the scorotron 15 includes a metal discharge shield 50 having a U-shaped cross section, and the discharge shield 50 extends along the longitudinal direction of the photosensitive drum 14. It is formed long. Further, inside the discharge shield 50, one or two (two in the illustrated example) of the discharge wires 51 made of metal such as tungsten are stretched along the longitudinal direction. Is configured to be applied with a high voltage of a predetermined polarity. Further, the corona discharge ions generated by applying a high voltage to the discharge wire 51 are emitted to the opening 52 of the discharge shield 50 uniformly toward the surface of the photosensitive drum 14. A grid 53 for controlling ions of corona discharge is provided, and a negative voltage having the same polarity as that of ions generated by corona discharge is applied to the grid 53, for example. In addition, on the back surface of the discharge shield 50, as will be described later, there is an opening 54 through which an air flow for removing discharge products such as ozone and nitrogen oxide (NOx) generated by corona discharge is passed. The discharge shield 50 is provided over substantially the entire length.

  Further, the digital color copying machine includes an air flow forming means 55 for forming an air flow in the vicinity of the charging device 15, as shown in FIGS. The air flow forming means 55 includes an intake duct 56 that guides air outside the machine to the back of the scorotron 15, an intake fan 57 (blower) that sucks outside air into the intake duct 56, and an opening 52 of the scorotron 15. An exhaust duct 58 that guides air from the outside of the machine to the outside of the machine and an exhaust fan 59 (blower) that exhausts the air to the outside of the machine through the exhaust duct 58.

  The intake fan 57 is mounted on the inner surface of the front cover of the digital color copying machine, and the air sucked from the lower end of the front cover is passed through a vertical duct (not shown) formed integrally with the inner surface of the front cover. Thus, the air is sucked into the opening 60 of the air intake duct 56. The intake duct 56 changes the direction of intake air by 90 degrees to the right while conveying outside air sucked from the opening 60 from the front side to the rear side of the copying machine main body 1, and is used for communication. As shown in FIG. 3, the air is guided to the back surface of the opening 52 of the scorotron 15 through the duct 61, and the air is sucked from the back surface of the opening 52 of the scorotron 15.

  On the other hand, the lower end of the exhaust duct 58 is opened downstream of the scorotron 15 and exhausts discharge products such as ozone and nitrogen oxide (NOx) discharged from the scorotron 15 through the opening 62. It is arranged to do. The air exhausted from the opening 62 of the exhaust duct 58 is conveyed to the rear side of the copying machine body 1 along the exhaust duct 58 and communicated with the exhaust duct 58 as shown in FIG. An exhaust fan 59 exhausts the air to the outside of the machine. The exhaust fan 59 need not be directly connected to the rear side of the exhaust duct 58, and may be connected via a communication duct (not shown).

  Further, in the digital color copying machine, as shown in FIG. 5, ducts 65, 66 for inhaling the air around the outer periphery of the corotron before transfer, the corotron before cleaning, or the fixing device 36 and discharging them outside the apparatus. 67 and 68 are also provided.

  FIG. 1A is a block diagram showing a control circuit of the digital color copying machine according to this embodiment.

  In FIG. 1A, reference numeral 100 denotes an MCU (Machine Control Unit) as a control means for controlling the operation of the digital color copying machine, and 101 denotes humidity and temperature as environmental conditions in which the digital color copying machine body 1 is installed. An environmental sensor as a detection means for performing the operation, 57 is an intake fan, and 59 is an exhaust fan. Further, the intake fan 57 and the exhaust fan 59 are configured to operate by PWM control of a DC voltage of 24V supplied from a low voltage power source, and when the intake fan 57 and the exhaust fan 59 are operated. The PWM control is configured to be performed based on the control of the MCU 100 by the PWM control circuit 102 provided in the MCU 100. The environmental sensor 101 is disposed inside the copying machine main body 1. However, as shown in FIG. 2, a fixing device is used so as not to be affected by humidity changes caused by equipment in the copying machine main body 1. A position on the opposite side of the fixing device 36 in the copying machine main body 1 and close to the front side, away from a heat source such as 36, a power supply circuit or a driving motor disposed on the rear side of the copying machine main body 1, etc. It is arranged.

  The MCU 100 detects humidity and temperature, at least humidity, as environmental conditions in which the digital color copying machine main body 1 is installed by the environmental sensor 101, and inhales air according to the humidity and temperature or the detected value of humidity. Control is performed so that the operating states of the fan 57 and the exhaust fan 59 are stopped or reduced.

  The intake fan 57 and the exhaust fan 59 normally operate during charging of the photosensitive drum 14 by the scorotron 15, and also operate for a predetermined time (for example, about several tens of milliseconds) after charging of the photosensitive drum 14 is completed. And controlled to stop.

  In the above configuration, in the digital color copying machine according to this embodiment, the charging device is operated by an air flow for removing ozone and nitrogen oxide (NOx) generated by corona discharge of the charging device as follows. As a result, it is possible to suppress the occurrence of insulation in the grid of the scorotron as described above, and to prevent deterioration in image quality due to the occurrence of charging unevenness.

  That is, in the digital color copying machine according to this embodiment, as shown in FIG. 2, after forming a full-color or black-and-white image, the surface of the photosensitive drum 14 is uniformly charged by the scorotron 15 as a charging device. Then, an image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (BK) is exposed on the surface of the photosensitive drum 14 by the ROS 12, and electrostatic latent images corresponding to the image information are exposed. Images are sequentially formed, and the electrostatic latent images corresponding to these yellow (Y), magenta (M), cyan (C), and black (BK) colors are converted into yellow (Y), By sequentially developing with magenta (M), cyan (C), and black (BK) developing devices 16Y, 16M, 16C, and 16BK, yellow ( ), Magenta (M), cyan (C), the color toner images of black (BK) are formed. The yellow (Y), magenta (M), cyan (C), and black (BK) toner images sequentially formed on the surface of the photosensitive drum 14 are sequentially superimposed on the intermediate transfer belt 21. Then, the image is primarily transferred from the intermediate transfer belt 21 onto the recording paper 27, and then transferred and heated and pressed by the fixing device 36 to form a full-color image.

  At that time, in the digital color copying machine, as shown in FIG. 2, when the surface of the photosensitive drum 14 is uniformly charged by the scorotron 15, ozone or nitrogen oxides are generated from the scorotron 15 along with corona discharge. A discharge product such as (NOx) is generated and released. Discharge products such as ozone and nitrogen oxides (NOx) generated and released along with this corona discharge are normally inhaled by the MCU 100 as part of the air flow forming means simultaneously with the start of charging of the photosensitive drum 14. By operating the fan 57 and the exhaust fan 59, the fan 57 and the exhaust fan 59 are removed by a filter (not shown) through the intake duct 56 and the exhaust duct 58 and then discharged outside the apparatus.

  By the way, in this embodiment, the MCU 100 is not always operated in synchronization with the start of charging of the photosensitive drum 14 by the scorotron 15, and the MCU 100 is provided with a digital color copying machine by the environment sensor 101. The humidity and temperature of the surrounding environment, at least the humidity, are detected, and the operation of the intake fan 57 and the exhaust fan 59 is stopped according to the detected value of the environment sensor 101.

  If the MCU 100 determines that the environmental condition is a low-humidity environment, for example, the relative humidity is less than 30%, according to the detection value of the environmental sensor 101, the scorotron 15 is displayed as shown in FIG. Even when charging of the photosensitive drum 14 is started, the operation of the intake fan 57 and the exhaust fan 59 is stopped so that no airflow acts on the scorotron 15.

  By doing so, when the photosensitive drum 14 is charged by the scorotron 15 in a low humidity environment, the grid 53 of the scorotron 15 is non-uniformly insulated due to the air flow acting on the scorotron 15. It is possible to suppress or prevent the occurrence of charging unevenness and adverse effects on image quality.

  If the MCU 100 determines that the environmental condition is a high humidity environment, for example, the relative humidity is 30% or more, according to the detection value of the environmental sensor 101, the scorotron 15 is shown in FIG. In synchronism with the charging of the photosensitive drum 14 by the air, the intake fan 57 and the exhaust fan 59 are operated to cause the air flow to act on the scorotron 15, and the ozone and nitrogen oxide (NOx) generated by the corona discharge of the scorotron 15 Is supposed to be removed. The surface of the photosensitive drum 14 is deteriorated due to discharge products such as ozone and nitrogen oxide (NOx) generated by the corona discharge, and image quality defects such as image flow are mainly generated. Since it is a high humidity environment, it is possible to suppress occurrence of image quality defects such as image flow by operating the intake fan 57 and the exhaust fan 59 in a high humidity environment.

  In the above embodiment, a case has been described in which the operating state of the intake fan 57 and the exhaust fan 59 is controlled according to the detected value of the relative humidity among the detected values of the environmental sensor 101. However, both the humidity and temperature are controlled. The operating state of the intake fan 57 and the exhaust fan 59 may be controlled according to the detected value. In this case, for example, the control is performed to stop the operation of the intake fan 57 and the exhaust fan 59 in a low temperature and low humidity environment where the relative humidity is less than 40% and the temperature is less than 10 ° C.

  In the first embodiment, when the environmental condition is low humidity, as shown in FIG. 1B, even if the scorotron 15 starts to charge the photosensitive drum 14, the intake fan 57 and the exhaust fan 59 The operation is stopped so that the airflow does not act on the scorotron 15. However, the present invention is not limited to this, and after the charging of the photosensitive drum 14 by the scorotron 15 is completed, as shown in FIG. The intake fan 57 and the exhaust fan 59 may be operated for a predetermined time T1 to treat discharge products such as ozone and nitrogen oxide (NOx) generated by corona discharge.

Embodiment 2
FIG. 7 shows a second embodiment of the present invention. The same parts as those of the first embodiment are denoted by the same reference numerals. In the second embodiment, at least a charging device is used. An image forming apparatus for forming an image, comprising an air flow forming means for forming an air flow in the vicinity of the charging device, and a detecting means for detecting an environmental condition in which the image forming apparatus is installed; And control means for controlling to reduce the operating state of the airflow forming means in accordance with the detection value of the detecting means.

  In other words, in the second embodiment, when the MCU 100 determines that the environmental condition is a low humidity environment, for example, the relative humidity is less than 30%, according to the detection value of the environment sensor 101, FIG. As shown, when the scorotron 15 starts to charge the photosensitive drum 14, the operating state of the intake fan 57 and the exhaust fan 59 as the air blower is reduced to 25% and the airflow acting on the scorotron 15 is operated. Is to be reduced. Further, even after the charging of the photosensitive drum 14 by the scorotron 15 is completed, the operating state of the intake fan 57 and the exhaust fan 59 is set to 70% for a predetermined time T, and ozone or nitrogen oxides generated from the scorotron 15 are operated. Discharge products such as (NOx) are processed.

  As a result, when the photosensitive drum 14 is charged by the scorotron 15 in a low humidity environment, a large amount of airflow acts on the scorotron 15, so that the grid 53 of the scorotron 15 is not uniform. It is possible to suppress the occurrence of charging unevenness and adverse effects on image quality. Even in a low-humidity environment, the intake fan 57 and the exhaust fan 59 operate with the operating state reduced to 25%, so that discharges of ozone, nitrogen oxide (NOx), etc. generated from the scorotron 15 occur. The product can be processed to some extent.

  When the MCU 100 determines that the environmental condition is a high humidity environment, for example, the relative humidity is 30% or more, according to the detection value of the environmental sensor 101, the scorotron 15 is shown in FIG. In synchronism with the charging of the photosensitive drum 14 by the operation, the intake fan 57 and the exhaust fan 59 are operated to increase to 40%, and air flow is applied to the scorotron 15 to generate ozone or nitrogen generated by corona discharge of the scorotron 15. The oxide (NOx) is removed. Further, even after the charging of the photosensitive drum 14 by the scorotron 15 is finished, the operating state of the intake fan 57 and the exhaust fan 59 is increased to 90% for a predetermined time T, and the ozone and nitrogen generated from the scorotron 15 are operated. Discharge products such as oxide (NOx) are processed.

  Therefore, in the second embodiment, the deterioration of the photosensitive drum 14 due to ozone and nitrogen oxide (NOx) generated by corona discharge of the scorotron 15 is suppressed, and image quality deterioration such as image density unevenness is prevented. In addition, the generation of insulation in the grid 53 of the scorotron 15 is suppressed by the air flow for removing ozone and nitrogen oxide (NOx) generated by the corona discharge of the scorotron 15, and the image quality is deteriorated due to the occurrence of charging unevenness. It is possible to prevent both.

  Other configurations and operations are the same as those of the above-described embodiment, and thus description thereof is omitted.

Embodiment 3
FIG. 8 shows a third embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. In the third embodiment, at least a charging device is used. An image forming apparatus for forming an image, wherein the image forming apparatus includes an airflow forming unit that forms an airflow in the vicinity of the charging device, and a timer built in the apparatus and a calendar function of the timer And control means for controlling to stop or reduce the operating state of the airflow forming means.

  That is, in the third embodiment, as shown in FIG. 8A, a timer circuit 110 having a calendar function is connected to the MCU 100, and the MCU 100 is connected to the timer circuit 110 according to the calendar function of the timer circuit 110. Control is performed so that the operating state of the airflow forming means 55 is stopped or reduced. Of course, the timer circuit 110 may be incorporated in the MCU 100.

  Then, according to the calendar function of the timer circuit 110, the MCU 100 charges the photosensitive drum 14 by the scorotron 15 from a specific date in spring to a specific date in autumn as shown in FIG. The intake fan 57 and the exhaust fan 59 are normally operated in synchronism with each other, and in synchronism with charging of the photosensitive drum 14 by the scorotron 15 from a certain date and time in autumn to a certain date and time in spring. The intake fan 57 and the exhaust fan 59 are stopped, or the operation state is reduced to operate.

  In such a case, the operating states of the intake fan 57 and the exhaust fan 59 can be controlled only by the calendar function of the timer circuit 110 without using an environmental sensor.

  Other configurations and operations are the same as those of the above-described embodiment, and thus description thereof is omitted.

Embodiment 4
FIG. 9 shows a fourth embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment, and in this fourth embodiment, the charging device has a humidity level. A humidifier for supplying high air is provided, and the humidifier is operated when the humidity is low.

  That is, in the fourth embodiment, as shown in FIG. 9, a humidifier 121 containing water 120 is provided at the side end of the intake duct 56 so as to communicate therewith, and is contained in the humidifier 121. The heated water 120 is heated by the heater 122 to generate water vapor, and the air flow humidified by the water vapor from the humidifier 121 is sucked into the charging device 15, so that it can be used as a charging device even in a low humidity environment. It is possible to suppress or prevent the grid 53 of the scorotron 15 from being insulated unevenly, and to prevent deterioration in image quality due to the occurrence of uneven charging.

  Other configurations and operations are the same as those of the above-described embodiment, and thus description thereof is omitted.

1 is a block diagram and timing chart showing a control circuit and operation of a digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing an image forming unit of a digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a block diagram showing the scorotron. FIG. 5 is a perspective view showing the intake and exhaust ducts of the digital color copying machine as the image forming apparatus according to Embodiment 1 of the present invention. FIG. 6 is a timing chart showing a modification of the operation of the digital color copying machine as the image forming apparatus according to the first embodiment of the present invention. FIG. 7 is a timing chart showing the operation of the digital color copying machine as the image forming apparatus according to Embodiment 2 of the present invention. FIG. 8 is a block diagram and timing chart showing a control circuit and operation of a digital color copier as an image forming apparatus according to Embodiment 3 of the present invention. FIG. 9 is a block diagram showing an image forming unit of a digital color copying machine as an image forming apparatus according to Embodiment 4 of the present invention.

Explanation of symbols

57: Intake fan (air flow forming means), 59: Exhaust fan (air flow forming means), 100: MCU (control means), 101: Environmental sensor (detection means).

Claims (6)

An image forming apparatus that forms an image using at least a charging device, the image forming apparatus including an air flow forming unit that forms an air flow in the vicinity of the charging device.
Detection means for detecting an environmental condition in which the image forming apparatus is installed, and control means for controlling the operation state of the airflow formation means to be stopped or reduced according to a detection value of the detection means. An image forming apparatus. The control of the operating state of the air flow forming means is to stop or reduce the air flow forming means when the humidity as the environmental condition is low, and to control the air flow when the humidity as the environmental condition is high. The image forming apparatus according to claim 1, wherein the forming unit is operated. The operation timing of the airflow forming unit is linked to the charging timing of the charging device, and control according to the detection value of the detecting unit is performed only during charging of the charging device. The image forming apparatus according to 2. The airflow forming means includes an intake duct that guides air to the back surface of the charging device, an intake fan that sucks outside air into the intake duct, and an exhaust duct that guides air to the outside from the opening of the charging device. 4. The image forming apparatus according to claim 1, further comprising an exhaust fan configured to exhaust air to the outside of the apparatus through the exhaust duct. 5. The image forming apparatus according to claim 1, wherein the charging device is provided with a humidifier that supplies high-humidity air, and the humidifier is operated when the humidity is low. An image forming apparatus that forms an image using at least a charging device, the image forming apparatus including an air flow forming unit that forms an air flow in the vicinity of the charging device.
An image forming apparatus comprising: a timer built in the apparatus; and a control unit that controls the operation state of the airflow forming unit to be stopped or reduced according to a calendar function of the timer.

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