JP2006106709A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure safety in the operation of a heating means without increasing replacement cost nor replacement operability in image carrier replacement and to prevent image flowing by using a heating means while solving problems of abnormal operation etc., as to an image forming apparatus equipped with an image carrier having, for example, large surface hardness. <P>SOLUTION: An outside air introduction duct 46 is provided having its outside end directed to outside an apparatus main body 10 and made two-pronged halfway and also having one internal end directed along the axis of a photoreceptor 11 (image carrier) at an end of the photoreceptor and the other internal end directed to an electrostatic charging device 12 disposed around the photoreceptor. A heater (heating means) 48 such as a PTC heater heating introduced outside air is arranged in the outside air introduction duct, and the outside air is introduced into the outside air introduction duct by a suction fan 47 arranged upstream from the heater and guided into the photoreceptor and to around the photoreceptor, passed inside and outside the photoreceptor, and discharged from the apparatus main body 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof. In particular, the present invention relates to an electrophotographic image forming apparatus that directly or indirectly transfers a toner image formed on an image carrier and records the image on a recording medium such as paper or an OHP film.

  Conventionally, in this type of electrophotographic image forming apparatus, the surface of the image carrier is uniformly charged with a charging device as the image carrier rotates, and writing is performed by exposing the surface of the image carrier to the surface of the image carrier. An electrostatic latent image is formed, toner is attached by a developing device to visualize the electrostatic latent image, and the toner image formed by the visualization is transferred by a transfer device to record the image on a recording medium. . The surface of the image carrier after the image transfer was cleaned with a cleaning device to prepare for image formation again.

  In such an electrophotographic image forming apparatus, in recent years, the surface hardness of an image carrier is increased by using a material typified by amorphous silicon, the wear resistance is improved, and the durability is improved. ing.

  However, an image carrier having such a large surface hardness generates a phenomenon called image flow (image blur). Image flow is a phenomenon in which an image becomes faint or the periphery of the image blurs. The cause of this image flow is that moisture in the air is adsorbed on the surface of the image carrier and the surface resistance decreases, and the charge of the formed electrostatic latent image flows in the peripheral direction, causing the potential to decrease and the boundary to be unclear. It is thought to be clear.

  The reason why moisture in the air is adsorbed on the surface of the image carrier is that when a charging charger is used as the charging device, the ozone generated by the corona discharge reacts with paper dust and toner components and discharges such as nitrate ions and ammonia ions. It is conceivable that the discharge product adsorbs moisture by generating a product and adhering to the surface of the image carrier. In a high-humidity environment, when discharge products adhere to the surface of the image carrier in this way, the surface resistance of the image carrier is reduced and image flow occurs. In particular, image flow is likely to occur immediately below the charging device where the adhesion of discharge products is concentrated. Further, the image flow often occurs when the image forming apparatus is started up at the beginning of the day.

  Therefore, in order to prevent the occurrence of the above-described image flow, a conventional image forming apparatus includes a heater inside the image carrier, and as described in Patent Document 1, for example, when necessary by temperature and humidity detection. Only by heating, the surface temperature of the image carrier is increased to prevent the adsorption of moisture in the air. For example, as described in Patent Document 2, the heater is turned on during warm-up after the power is turned on, and then the aging process is performed to remove moisture on the surface of the image carrier.

JP 2002-40876 A Japanese Patent No. 2515826 JP 10-149082 A

  However, as described above, in the conventional configuration in which the heater is provided inside the image carrier, when the image carrier is replaced due to failure or life, if it is replaced together with the heater, the maintenance cost increases, and the image carrier is left with the heater remaining. When only the body is replaced, the flange has to be removed from the image carrier and the heater must be replaced, and there has been a problem that maintenance workability is very poor. In addition, AC power must be supplied from the end of the rotating image carrier. In particular, when the heater is turned on while the image carrier is rotating, there is a safety problem, and abnormal operation is caused by noise. There was a problem that it might occur.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is, for example, in an image forming apparatus provided with an image carrier having a large surface hardness, without increasing the exchange cost and the exchange workability at the time of image carrier exchange, and at the time of operation of heating means such as a heater. An object of the present invention is to prevent the occurrence of image flow using a heating means while ensuring safety and eliminating the occurrence of problems such as abnormal operation.

  In order to achieve this object, the invention according to claim 1 is directed to an image forming apparatus that introduces outside air through the outside air introduction duct, guides the outside air into the image bearing body, passes the image bearing body, and discharges it outside the image forming apparatus main body. The outside air introduction duct is provided with heating means such as a heater for warming the introduced outside air.

  Then, the outside air introduced through the inside of the outside air introduction duct is heated by operating the heating means, guided to the inside of the image carrier, passed through the image carrier, and then discharged out of the image forming apparatus main body.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the outside air introduction duct is branched at a position downstream of the heating means along the flow of the introduced outside air, and one of them introduces the introduced outside air into the image carrier. The other is characterized in that the introduced outside air is guided around the image carrier.

  The introduced outside air warmed by the heating means is divided into two directions, one being led into the image carrier and the other being led around the image carrier.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the introduced outside air is guided to a charging device position around the image carrier by an outside air introduction duct.

  Then, the introduced outside air heated by the heating means is guided to the charging device position around the image carrier.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a PTC heater is used as a heating unit.

  Then, the PTC heater is turned on and the introduced outside air is warmed by the PTC heater.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, an intake fan that takes in outside air is provided at a position upstream of the heating means along the flow of the introduced outside air. Features.

  And it sucks with an intake fan and introduces outside air through the outside air introduction duct.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the introduced outside air is discharged out of the main body of the image forming apparatus through the exhaust duct.

  Then, the introduced outside air warmed by the heating means is discharged outside the image forming apparatus main body through the exhaust duct.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect, when the heating means is operated, the intake fan is turned on and the exhaust fan is turned off.

  When the heating means is operated, only the outside air is sucked by the intake fan, and the exhaust by the exhaust fan is stopped.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the heating means is operated during warm-up immediately after the power is turned on.

  The heating means for warming the introduced outside air operates during warm-up immediately after the image forming apparatus is turned on.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the image forming apparatus further includes a temperature detection unit that detects a temperature of the image carrier, and heating is performed based on a detection result of the temperature detection unit. The means is controlled to operate.

  The heating means for warming the introduced outside air controls the operation based on the detection result of the temperature detection means for detecting the temperature of the image carrier.

  According to the first aspect of the invention, the heating means is operated to warm the outside air introduced through the inside of the outside air introduction duct, is guided to the inside of the image carrier, passes through the inside of the image carrier, and is discharged outside the image forming apparatus main body. With a simple configuration that simply installs heating means inside the outside air introduction duct, the surface temperature of the image carrier is raised by the heated outside air, preventing the adsorption of moisture in the air, and the moisture on the surface of the image carrier is reduced. Therefore, the occurrence of image flow can be prevented.

  In addition, since the heating means is provided in the outside air introduction duct and is not built in the image carrier, it is possible to replace only the image carrier when the image carrier is replaced due to failure or lifetime, thus reducing the replacement cost of the image carrier. In addition, the workability of replacing the image carrier can be improved. Furthermore, since no heating means is provided in the rotating image carrier, safety during operation of the heating means can be ensured and problems such as abnormal operation due to the occurrence of noise can be solved.

  According to the second aspect of the present invention, since the introduced outside air heated by the heating means is divided into two directions, one is led into the image carrier and the other is guided around the image carrier, so that the image carrier is warmed from inside and outside. The surface temperature can be efficiently increased to the target temperature in a short time.

  According to the third aspect of the present invention, since the introduced outside air heated by the heating means is guided to the charging device position around the image carrier, the temperature at the charging device position where the discharge product easily adheres is quickly increased, and the image Generation of flow can be prevented. Other than the charging device position, the temperature rises relatively moderately due to the warm air passing through the image carrier, and although the temperature is lower than the charging device position, the temperature rises uniformly and image flow can be prevented.

  According to the invention described in claim 4, since the PTC heater is used as the heating means, the heating means can be reduced in size, the installation of the heating means in the outside air introduction duct is facilitated, the PTC heater is turned on and the PTC heater is turned on. The introduced outside air can be warmed with a heater.

  According to the fifth aspect of the invention, since the outside air is introduced through the outside air introduction duct by being sucked by the intake fan, the outside air can be reliably introduced through the outside air introduction duct using the intake fan.

  According to the sixth aspect of the present invention, since the introduced outside air warmed by the heating means is discharged out of the image forming apparatus main body through the exhaust duct, ozone around the image carrier can be reliably discharged.

  According to the seventh aspect of the present invention, when the heating means is operated, only the outside air is sucked by the intake fan, and the exhaust by the exhaust fan is stopped, so that the inside of the image forming apparatus main body is not discharged without discharging the warm introduced outside air. The temperature increase efficiency of the image carrier is increased, and as a result, energy consumption can be reduced.

  According to the eighth aspect of the present invention, since the heating unit is operated during the warm-up immediately after the image forming apparatus is turned on, the heating unit is operated immediately after the image forming apparatus is turned on. The surface temperature of the image carrier can be raised to efficiently prevent the occurrence of image flow. Since the temperature of the image carrier is raised using the warm-up time, it is possible to prevent the image from flowing without using extremely high temperature heating means.

  According to the ninth aspect of the invention, since the heating means is controlled based on the detection result of the temperature detecting means for detecting the temperature of the image carrier, when the surface temperature of the image carrier is below a certain temperature, It is possible to operate the heating means efficiently by not operating the heating means and turning off the light when excessively rising.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows an overall schematic configuration of an internal mechanism in a digital copying machine (image forming apparatus) according to the present invention as seen from the front side.

  Reference numeral 10 in the figure denotes a copying machine main body (image forming apparatus main body). A drum-shaped photosensitive member (image carrier) 11 is provided in the copying machine main body 10, and a charging device 12 using a charging charger, a developing device 13, and a transfer / conveying device are provided in parallel with the photosensitive member 11. 14. A cleaning device 15 is disposed. On top of them, a writing device 16 is provided.

  On the left side of the cleaning device 15 in the figure, a fixing device 17 is provided in parallel with the photoreceptor 11. The fixing device 17 is provided with a fixing roller 18 incorporating a heater and a pressure roller 19 that presses against the fixing roller 18 from below.

  A document reading device 20 is provided in the upper part of the apparatus main body 10. The document reading device 20 is provided with a light source a, a plurality of mirrors b, an imaging lens c, an image sensor d such as a CCD, and the like. On the other hand, a duplex unit 21 is provided in the lower part of the apparatus main body 10.

  By the way, the apparatus main body 10 is placed on the paper feed table 22. In the paper feed table 22, paper feed trays 23 are provided in three upper and lower stages. Each of the paper feed trays 23 is provided with a paper feed path 24 extending below the photoconductor 11. A paper discharge path 25 is provided from the outlet of the fixing device 17, and a reversing path 26 that branches from the middle and communicates with the duplex unit 21 is formed.

  Now, the contact glass 27 is installed on the upper surface of the apparatus main body 10 described above. An automatic document feeder (ADF) 28 is mounted on the apparatus main body 10 so as to be able to be opened and closed with the back side as a fulcrum so as to cover the contact glass 27.

  In the illustrated digital copying machine, an operation panel 30 is provided supported by an arm 29 extending from the apparatus main body 10. In the paper feed table 22, two toner bottles 31 and one waste toner bottle 32 are mounted side by side next to the three-stage paper feed tray 23.

  When taking a copy using this digital copying machine, the original is set on the automatic document feeder 28 or the automatic document feeder 28 is opened and the original is directly set on the contact glass 27. Then, when a start switch (not shown) on the operation panel 30 is pressed and the automatic document feeder 28 is driven to convey the document conveyed on the contact glass 27 or when the document is set on the contact glass 27 in advance, the setting is performed. The original is read by the original reading device 20 and converted into an electrical digital image signal.

  At the same time, an appropriate paper feed roller 33 is rotated to feed out a recording medium such as paper / OHP film from the corresponding paper feed tray 23 among the plurality of paper feed trays 23 provided in multiple stages in the paper feed table 22 to feed the paper. It is put in the path 24 and conveyed by the conveying roller 34, and is abutted against the registration roller 35 and stopped. Then, the registration roller 35 is rotated in synchronism with the rotation of the photoconductor 11, and is sent below the photoconductor 11.

  On the other hand, when a start switch (not shown) is pressed, the photosensitive member 11 is rotated clockwise in the drawing at an appropriate timing. Then, along with the rotation of the photoconductor 11, the surface is first uniformly charged by the charging device 12, and then the laser light L is irradiated based on the digital image signal according to the reading content read by the document reading device 20 described above. Writing is performed by the writing device 16 to form an electrostatic latent image on the surface of the photoconductor 11, and then a toner is attached by the developing device 13 to visualize the electrostatic latent image. Form an image.

  Then, the toner image formed on the photoconductor 11 is transferred by the transfer / conveyance device 14 to the recording medium fed below the photoconductor 11 as described above. After the image transfer, the photosensitive member 11 is cleaned by removing residual toner with a cleaning device 15, and is neutralized by, for example, a neutralizing device (not shown) to initialize the surface to prepare for the next similar image formation.

  On the other hand, the recording medium after the image transfer is conveyed by the transfer / conveyance device 14 and put into the fixing device 17, and heat and pressure are applied by the fixing roller 18 and the pressure roller 19 to fix the transferred image. Thereafter, the paper is discharged out of the apparatus main body 10 through the paper discharge path 25.

  When recording an image on both sides of the recording medium, it is put from the paper discharge path 25 into the reversing path 26, reversed by the duplex unit 21 and put again into the paper feeding path 24, and the transfer / conveying device 14 also puts the recording medium on the back side After separately transferring the image formed on the photoconductor 11, the transferred image is fixed by the fixing device 17 and discharged.

  FIG. 2 shows an exhaust device that is provided in the copying machine main body 10 of the digital copying machine shown in FIG. 1 and that discharges ozone and prevents image flow.

  In the digital copying machine shown in FIG. 1, the above-described photoconductor 11 is made of amorphous silicon and has a drum 40 whose surface hardness is increased to improve wear resistance and durability, and a circular flange fitted to both ends thereof. 41A and 41B. Both the flanges 41A and 41B are provided with a plurality of fan-shaped vent holes 43 around the central shaft hole. Then, both ends of the photosensitive member shaft through the central shaft hole 42 are rotatably supported by a pair of opposed side plates (not shown) via bearings.

  The inner end of the outside air introduction duct 46 is directed to the flange 41 </ b> A on the back side of the photoreceptor 11. The outside air introduction duct 46 has an outer end facing the outside of the apparatus main body 10 and is divided into two branches in the middle, with one of the inner ends directed in the axial direction of the photoreceptor at the end on the back side of the photoreceptor 11 and the other around the photoreceptor 11. To the charging device 12 position.

  The outside air introduction duct 46 includes an intake fan 47 that takes outside air into the apparatus main body 10 in the outer end. The intake fan 47 may be provided so as to connect the outer end of the outside air introduction duct 46 outside the outside air introduction duct 46 instead of inside the outside air introduction duct 46, and is provided facing the outside from the side surface of the apparatus main body 10.

  A heater 48 is provided in the outside air introduction duct 46 as a heating means for warming the introduced outside air. If a PTC (Positive Temperature Coefficient) heater is used as the heater 48, the heater 48 can be miniaturized and the heater 48 can be easily installed in the outside air introduction duct 46. The intake fan 47 is provided at the upstream position of the heater 48 along the flow of the introduced outside air indicated by the arrow a in the figure, and the outside air introduction duct 46 is branched at the downstream position.

  Around the photoconductor 11, a temperature detection means 49 such as a thermistor or a temperature sensor for detecting the surface temperature of the photoconductor 11 is provided, and lighting of the heater is controlled based on the detection result of the temperature detection means 49. Of course, the temperature detecting means 49 may be a contact type that contacts the surface of the photoreceptor 11 or a non-contact type that does not contact.

  Around the photoreceptor 11, an inner end of an exhaust duct 50 that discharges air around the photoreceptor to the outside of the apparatus main body 10 is provided. The exhaust duct 50 is provided with an inner end that opens long in the direction of the photoreceptor axis, and a dustproof filter 51 is attached thereto. And the exhaust fan 52 is provided in the back surface position by narrowing down a cross section gradually toward the back surface direction of the apparatus main body 10. The exhaust duct 50 is bent at a right angle and extended along the back surface, and an ozone filter 53 is installed at the outer end. The ozone filter 53 is provided so as to be exchangeable from the side surface of the apparatus main body 10 to the outside.

  When the apparatus main body 10 is driven, the intake fan 47 and the exhaust fan 52 are operated to take in the outside air into the apparatus main body 10 and are introduced through the outside air introduction duct 46 to branch the introduced outside air. Is guided into the photoconductor 11 from the vent hole 43 of the flange 41A, and passes through the photoconductor 11 in the axial direction of the photoconductor 11 as indicated by an arrow b, and is discharged out of the photoconductor 11 through the vent hole 43 of the flange 41B on the front side. At the same time, the other is guided around the photoconductor 11 through the charging device 12 as shown by an arrow c, and an air flow is created around the photoconductor 11.

  The introduced outside air is then discharged through the dust filter 51 by the exhaust fan 52, and after removing dust such as floating toner and floating paper powder, it is sucked into the exhaust duct 50 and ozone is passed through the exhaust duct 50 as indicated by an arrow d. After guiding to the filter 53 and removing ozone in the exhaust gas with the ozone filter 53, the ozone is discharged out of the apparatus body 10 as indicated by an arrow e. Thereby, the ozone around the photoconductor 11 can be reliably removed and the photoconductor 11 can be cooled.

  Incidentally, in most cases, the image flow occurs immediately after the copying machine is started up. Therefore, the heater 48 is turned on during warm-up immediately after the copying machine is turned on. Then, the heater 48 is turned on immediately after turning on the power of the copying machine in which image flow is most likely to occur, and the surface temperature of the photoconductor 11 can be raised to efficiently prevent image flow. Since the temperature of the photoconductor 11 is raised to about 40 ° C. using the warm-up time, image flow can be prevented without using an extremely high temperature heater.

  Further, since the image flow occurs in a high temperature and high humidity environment, it is not necessary to turn on the heater 48 below a certain temperature. On the other hand, if the surface temperature of the photoconductor 11 rises too much, a problem may occur. Therefore, the heater 48 is controlled to be turned on based on the detection result of the temperature detecting means 49 so that the heater 48 is not turned on when the surface temperature of the photoconductor 11 is lower than a certain temperature, and is turned off when the surface temperature rises excessively. Thereby, the heater 48 can be lighted efficiently.

  For example, when the power of the copying machine is turned on and the copying machine starts warming up, the temperature detection means 49 detects the surface temperature of the photoconductor 11, and when the surface temperature is, for example, 25 ° C. or more, the heater 48 is turned on. Then, the introduced outside air is warmed, guided into the photoconductor 11 and passed through the photoconductor 11, and the surface temperature of the photoconductor 11 is raised. When the surface temperature of the photoconductor 11 becomes 45 ° C. or more, for example, the heater 48 is turned off.

  As a result, the surface temperature of the photoconductor 11 is raised by the heated introduced outside air with a simple configuration in which the heater 48 is additionally installed in the outside air introduction duct 46, and the adsorption of moisture in the air is prevented. It is possible to eliminate moisture on the surface and prevent the occurrence of image flow.

  In addition, since the heater 48 is provided in the outside air introduction duct 46 and is not built in the photoconductor 11, when the photoconductor 11 is replaced due to failure or life, only the photoconductor 11 can be replaced, and the replacement cost of the photoconductor 11 is reduced. In addition to the reduction, the work of replacing the heater 48 can be eliminated and the workability of replacing the photoconductor 11 can be improved. Further, since the rotating photoconductor 11 is not provided with the heater 48, it is possible to ensure safety when the heater 48 is turned on and to solve problems such as abnormal operation due to generation of noise.

  It should be noted that when the heater 48 is turned on, only the outside air is sucked by the intake fan 47 and the exhaust by the exhaust fan 52 is stopped. In this way, the heated introduced outside air is accumulated in the copier apparatus main body 10 without being discharged, and the temperature rise efficiency of the photoconductor 11 is increased, and as a result, energy consumption can be reduced.

  According to the illustrated digital copying machine, the outside air heated by the heater 48 is divided into two directions, one is led into the photoconductor 11 and the other is guided around the photoconductor 11, so that the photoconductor 11 is warmed from inside and outside. The surface temperature can be efficiently increased to the target temperature in a short time. Further, since the introduced outside air heated by the heater 48 is guided to the position of the charging device 12 around the photoconductor 11, the temperature at the position of the charging device 12 where discharge products are likely to adhere particularly quickly increases when the charging charger is used. Generation of flow can be prevented. Other than the charging device 12 position, the temperature rises relatively moderately due to the warm air passing through the photoconductor 11, and although the temperature is lower than the charging device 12 position, the temperature rises uniformly to prevent image flow. Can do.

1 is an overall schematic configuration diagram showing an internal mechanism in a digital copying machine according to the present invention as viewed from the front side; FIG. 2 is a perspective view showing an exhaust device provided in the apparatus main body of the digital copying machine shown in FIG. 1 for discharging ozone and preventing image flow.

Explanation of symbols

10 Copying machine main body (image forming device main body)
11 Photoconductor (image carrier)
DESCRIPTION OF SYMBOLS 12 Charging device 40 Drum 41A, 41B Flange 42 Center shaft hole 43 Vent hole 46 Outside air introduction duct 47 Intake fan 48 Heater (heating means)
49 Temperature detection means 50 Exhaust duct 51 Dust-proof filter 52 Exhaust fan 53 Ozone filter

Claims (9)

In the image forming apparatus that introduces outside air through the outside air introduction duct and guides it into the image carrier, passes through the image carrier, and then discharges it outside the image forming apparatus main body.
An image forming apparatus comprising heating means in the outside air introduction duct.   The outside air introduction duct is branched at a position downstream of the heating means along the flow of the introduced outside air, one leads the introduced outside air into the image carrier, and the other guides the introduced outside air around the image carrier. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the outside air introduction duct guides the introduced outside air to a charging device position around the image carrier.   The image forming apparatus according to claim 1, wherein a PTC heater is used as the heating unit.   5. The image forming apparatus according to claim 1, further comprising an intake fan at a position upstream of the heating unit along a flow of introduced outside air.   6. The image forming apparatus according to claim 1, wherein the introduced outside air is discharged outside the image forming apparatus main body through the exhaust duct.   The image forming apparatus according to claim 5, wherein when the heating unit is operated, the intake fan is turned on and the exhaust fan is turned off.   The image forming apparatus according to claim 1, wherein the heating unit is operated during warm-up immediately after power is turned on.   The image according to any one of claims 1 to 8, further comprising temperature detection means for detecting a temperature of the image carrier, and controlling the operation of the heating means based on a detection result of the temperature detection means. Forming equipment.

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