JP5500429B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer that includes a cooling unit that cools an object to be cooled.

  As this type of image forming apparatus, the one described in Patent Document 1 is known. This image forming apparatus forms an image by an electrophotographic method. The electrostatic latent image is developed by attaching toner to the electrostatic latent image carried on the surface of the photosensitive member serving as a latent image carrier by a developing device. Then, the toner image obtained by the development is transferred from the photosensitive member to the surface of the recording paper through the intermediate transfer belt by the transfer device. The recording paper on which the toner image is formed in this manner is fixed on the toner transfer surface by heating and heating the toner transfer surface in the fixing device. In the developing device, the temperature of the device is raised by the heat generated from the fixing device, so that the toner inside may be melted and adversely affect the developing performance. Therefore, the heat receiving portion of the cooling device is in close contact with the developing device. This cooling device circulates and conveys a coolant as a cooling medium between the heat receiving portion and the heat radiating portion, and releases the heat taken from the developing device by the heat receiving portion and transmitted to the cooling liquid from the coolant at the heat radiating portion. . By cooling the developing device by such a liquid cooling method, the inside of the developing device is compared with an image forming device having a simple configuration in which the air inside the housing is discharged to the outside by a fan and the rise in the temperature inside the apparatus is suppressed. Occurrence of toner melting can be suppressed.

  However, when using a general molding method (for example, extrusion molding) as the casing of the developing device from the viewpoint of cost reduction, the casing surface inevitably has a subtle wavy curve (hereinafter referred to as “extrusion molding”). The surface swell). Even if the flat surface of the heat receiving part of the cooling device is brought into close contact with such a casing, the heat receiving part can be satisfactorily adhered only to the region corresponding to the peak portion of the surface waviness in the entire area of the casing surface. First, in the region corresponding to the valley portion of the surface undulation, poor adhesion of the heat receiving portion occurs. This may make it difficult to cool the developing device satisfactorily.

  In the image forming apparatus described in Patent Document 1, the developing device is cooled as a cooled body. However, in the case where a cooled body different from the developing apparatus is cooled, similarly, There is a risk of causing poor adhesion of the heat receiving portion due to surface waviness.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus capable of suppressing poor adhesion between a cooled object and a heat receiving part due to surface waviness of the cooled object. Is to provide.

In order to achieve the above object, the invention of claim 1 is directed to developing a latent image carrier that carries a latent image, and developing the latent image carried on the surface of the latent image with toner in order to form an image on a recording member. And an image forming unit including a transfer unit that transfers the toner image obtained by development from the latent image carrier to the recording member, and a cooling unit that cools the developing unit, and is in close contact with the developing unit. A heat receiving portion that receives heat from the developing unit, a heat radiating portion that releases heat, a cooling medium that is circulated through the inside of the heat receiving portion and the inside of the heat radiating portion, and the heat receiving portion that is used for conveying the cooling medium. In the image forming apparatus having the cooling unit with a pipe member that connects the heating unit and the heat radiating unit, the heat receiving unit includes a plurality of units for cooling different portions of the developing unit, and the plurality of heat receiving units. Are arranged side by side in the toner conveying direction in the developing means, and different portions in the toner conveying direction in the developing means are cooled by the heat receiving portions, and the cooling for the plurality of heat receiving portions is performed. A flexible member is used as the tube member for transmitting and receiving the medium .
Also, the invention of claim 2, connecting the image forming apparatus according to claim 1, their heat receiving portion as between a plurality of said heat receiving portion transmitting and receiving the cooling medium, with the tube member of a flexible It is characterized by that.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the flexible tube member is connected to a non-opposing surface with respect to the plurality of heat receiving portions. It is characterized by.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the plurality of urging means for individually urging and closely contacting the plurality of heat receiving portions toward the cooled body respectively. Is provided.
According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, a coil spring is used as each of the plurality of urging units.

  In these inventions, the plurality of heat receiving portions of the cooling means are brought into close contact with different locations on the surface of the body to be cooled. And for the reason demonstrated below, some of these several heat-receiving parts are closely_contact | adhered more favorably with respect to the valley part of the surface wave | undulation of a to-be-cooled body. That is, the surface undulation generated on the solid surface of the object to be cooled obtained by a general molding method has a relatively large length from a peak part to a valley part, for example, several centimeters to several tens of centimeters. In this invention, it becomes possible to aim at cooling by making a heat receiving part which mutually differs with respect to the peak part and trough part of this surface wave | undulation. In such cooling, among the plurality of heat receiving portions, if the heat receiving portion facing the valley portion of the surface waviness can be brought closer to the body to be cooled than the heat receiving portion in close contact with the peak portion, Although it becomes possible to make it adhere | attach well on a trough part, for that purpose, it is necessary to separate the former heat receiving part from the latter heat receiving part, and to move it. Therefore, in the present invention, the tube member for transmitting and receiving the cooling medium to and from the plurality of heat receiving portions is not a highly rigid material that cannot be deformed as in the prior art, but has a deformable flexibility. Is connected. In such a configuration, the heat receiving part facing the valley of the surface undulation of the body to be cooled can be separated from the heat receiving part in close contact with the peak part and moved, so that the valley can be satisfactorily adhered. Compared with the prior art, it is possible to suppress poor adhesion between the cooled object and the heat receiving portion.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 3 is a partially enlarged configuration diagram illustrating a part of an internal configuration of a printer unit in the copier. FIG. 3 is an enlarged configuration diagram showing a process unit for Y of the printer unit. FIG. 2 is a configuration diagram showing a cooling device of the copier and developing devices for respective colors as cooling bodies. FIG. 2 is an enlarged configuration diagram showing a developing device for Y and its peripheral configuration in the copier. FIG. 3 is an enlarged plan sectional view showing the developing device and a heat receiving unit for Y. FIG. 3 is an enlarged side view showing the developing device and the heat receiving unit. FIG. 3 is an enlarged side view showing a developing device for Y and a heat receiving unit for Y in the copying machine according to the embodiment. FIG. 9 is an enlarged side view showing a developing device for Y and a heat receiving unit for Y in a modified example of the copier. FIG. 10 is a schematic configuration diagram illustrating an example of a cooling device in a conventional image forming apparatus. FIG. 3 is a perspective view showing a process unit and a heat receiving unit of the cooling device in the image forming apparatus. FIG. 3 is an enlarged plan sectional view showing a developing device and a heat receiving unit of the process unit.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a copying machine that forms an image by an electrophotographic method will be described.
First, a basic configuration of the copying machine according to the embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating a copying machine according to an embodiment. The copying machine includes a printer unit 1, a blank paper supply device 100, and a document conveyance reading unit 150. The document conveyance reading unit 150 includes a scanner 160 as a document reading device fixed on the printer unit 1 and an ADF 170 as a document conveyance device supported by the scanner 160.

  The blank paper supply apparatus 100 includes two paper feed cassettes 102 and 103, two pairs of separation roller pairs 104 and 105, a paper feed path 106, a plurality of transport roller pairs 107, and the like arranged in multiple stages in the paper bank 101. doing. Each of the two paper feed cassettes 102 and 103 is housed in a paper bundle in which a plurality of recording papers (not shown) are stacked. Based on the control signal from the printer unit 1, the sending rollers 102 a and 103 a are driven to rotate, and the uppermost recording paper in the paper bundle is sent out toward the paper feed path 106. The fed recording paper is separated into one sheet by the pair of separation rollers 104 and 105 and then enters the paper feed path 106. Then, the sheet is fed to the first receiving branch path 30 of the printer unit 1 through the conveyance nips of the plurality of conveyance roller pairs 107 provided in the sheet feeding path 106.

  The printer unit 1 includes four process units 2Y, 2M, 2C, and 2K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. Also, the first receiving branch path 30, the receiving conveyance roller pair 31, the manual feed tray 32, the manual separation roller pair 33, the second receiving branch path 34, the manual conveyance roller pair 35, the pre-transfer conveyance path 36, the registration roller pair 37, the conveyance A belt unit 39, a fixing unit 43, a switchback device 46, a discharge roller pair 47, a discharge tray 48, a switching claw 49, an optical writing unit 50, a transfer unit 60, and the like are also provided. The process units 2Y, 2M, 2C, and 2K have drum-shaped photoreceptors 3Y, 3M, 3C, and 3K that are latent image carriers arranged at a predetermined pitch.

  A pre-transfer conveyance path 36 for conveying a recording sheet immediately before a secondary transfer nip, which will be described later, is branched into a first reception branch path 30 and a second reception branch path 34 on the upstream side in the paper conveyance direction. The recording paper fed from the paper feed path 106 of the blank paper supply device 100 is received by the first receiving branch path 30 and then passed through the transport nip of the receiving transport roller pair 31 disposed in the first receiving branch path 30. Then, it is sent to the pre-transfer conveyance path 36.

  A manual feed tray 32 is disposed on the side surface of the housing of the printer unit 1 so as to be openable and closable with respect to the housing. The uppermost recording paper in the manually fed paper bundle is sent out toward the second receiving / branching path 34 by the feed roller 32 a of the manual feed tray 32. After being separated into one sheet by the manual feed separation roller pair 33 and sent to the second receiving branch path 34, it passes through the transport nip of the manual feed roller pair 35 disposed in the second receiving branch path 34. Then, it is sent to the pre-transfer conveyance path 36.

  The optical writing unit 50 includes a laser diode, a polygon mirror, various lenses (not shown), etc., and is based on image information read by a scanner 160 described later or image information sent from an external personal computer. Drive the laser diode. Then, the photoconductors 3Y, M, C, and K of the process units 2Y, M, C, and K are optically scanned. Specifically, the photoconductors 3Y, 3M, 3C, and 3K of the process units 2Y, 2M, 2C, and 2K are rotated in the counterclockwise direction in the drawing by driving means (not shown). The optical writing unit 50 performs an optical scanning process by irradiating the driven photosensitive members 3Y, 3M, 3C, and 3K while deflecting laser light in the direction of the rotation axis. Thereby, electrostatic latent images based on Y, M, C, and K image information are formed on the photoreceptors 3Y, 3M, 3C, and 3K.

  FIG. 2 is a partially enlarged configuration diagram illustrating a part of the internal configuration of the printer unit 1 in an enlarged manner. The process units 3K, Y, M, and C for the respective colors support the photosensitive member as a latent image carrier and various devices arranged around it on a common support as a unit. It is detachable from the printer unit main body. The configuration is the same except that the colors of the toners used are different. Taking the process unit 2Y for Y as an example, this has a developing device 4Y for developing an electrostatic latent image formed on the surface of the photosensitive member 3Y as a latent image carrier into a Y toner image. doing. Further, it also includes a drum cleaning device 18Y that cleans transfer residual toner adhering to the surface of the photoreceptor 3Y after passing through a Y primary transfer nip described later. This copying machine has a so-called tandem configuration in which four process units 2Y, 2M, 2C, and 2K are arranged along an endless movement direction with respect to an intermediate transfer belt 61 described later.

  FIG. 3 is an enlarged configuration diagram showing the Y process unit 2Y. As shown in the figure, the process unit 2Y includes a developing device 4Y, a drum cleaning device 18Y, a charge eliminating lamp 17Y, a charging roller 16Y, and the like around the photoreceptor 3Y.

  As the photoreceptor 3 </ b> Y, a drum-like member is used in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a base tube made of aluminum or the like. However, an endless belt may be used.

  The developing device 4Y develops a latent image using a two-component developer (hereinafter simply referred to as developer) containing a magnetic carrier (not shown) and non-magnetic Y toner. And it has the stirring part 5Y which conveys the developer accommodated in the inside while stirring, and the developing part 9Y which develops the electrostatic latent image on the photoreceptor 3Y. The developing device 4Y may be of a type that performs development with a one-component developer that does not include a magnetic carrier, instead of the two-component developer.

  The agitating unit 5Y is provided at a position lower than the developing unit 9Y. The first conveying screw 6Y and the second conveying screw 7Y are arranged in parallel to each other, a partition plate provided between these screws, and the bottom surface of the casing. The toner density sensor 8Y and the like provided in the printer.

  The developing unit 9Y includes a developing roll 10Y that faces the photoreceptor 3Y through the opening of the casing, a doctor blade 13Y that makes its tip close to the developing roll 10Y, and the like. The developing roll 10Y includes a cylindrical developing sleeve 11Y made of a nonmagnetic material, and a magnet roller 12Y provided inside the developing roll 11Y so as not to rotate. The magnet roller 12Y has a plurality of magnetic poles arranged in the circumferential direction. Each of these magnetic poles applies a magnetic force to the developer on the sleeve at a predetermined position in the rotational direction. As a result, the developer sent from the stirring unit 5Y is attracted and carried on the surface of the developing sleeve 11Y, and a magnetic brush along the magnetic field lines is formed on the sleeve surface.

  The magnetic brush is transported to a developing region facing the photoreceptor 3Y after being regulated to an appropriate layer thickness when passing through a position facing the doctor blade 13Y as the developing sleeve 11Y rotates. Then, Y toner is transferred onto the electrostatic latent image by the potential difference between the developing bias applied to the developing sleeve 11Y and the electrostatic latent image on the photoreceptor 3Y, thereby contributing to development. Further, as the developing sleeve 11Y rotates, the developing sleeve 9Y returns to the developing portion 9Y again, and after the release from the sleeve surface due to the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller 12Y, the developing sleeve 11Y returns to the stirring portion 5Y. An appropriate amount of toner is supplied to the developer in the stirring unit 5Y based on the detection result of the toner density sensor 8Y.

  As the drum cleaning device 18Y, a system that presses the cleaning blade 20Y made of polyurethane rubber against the photoreceptor 3Y is used, but another system may be used. For the purpose of improving the cleaning property, this copying machine employs a system having a fur brush 19Y whose outer peripheral surface is in contact with the photoreceptor 3Y so as to be rotatable in the direction of the arrow in the figure. The fur brush 19Y also serves to apply the lubricant to the surface of the photoreceptor 3Y while scraping the lubricant from a solid lubricant (not shown) into a fine powder.

  The toner attached to the fur brush 19Y is transferred to the electric field roller 21Y to which a bias is applied while rotating in contact with the fur brush 19Y in the counter direction. And after scraping off from the electric field roller 21Y by the scraper 22Y, it falls on the collection | recovery screw 23Y.

  The collection screw 23Y conveys the collected toner toward the end of the drum cleaning device 18Y in the direction perpendicular to the drawing surface, and delivers it to an external recycling conveyance device. A recycle conveyance device (not shown) sends the delivered toner to the developing device 4Y for recycling.

  The neutralization lamp 17Y neutralizes the photoreceptor 3Y by light irradiation. The surface of the photoreceptor 3Y that has been neutralized is uniformly charged by the charging roller 16Y, and then subjected to optical scanning by the optical writing unit described above. The charging roller 16Y is rotationally driven while receiving a charging bias from a power source (not shown). Instead of the charging method using the charging roller 16Y, a scorotron charger method in which charging processing is performed in a non-contact manner on the photoreceptor 3Y may be employed.

  In FIG. 2 described above, Y, M, C, and K toner images are formed on the surfaces of the photoreceptors 3Y, M, C, and K of the four process units 2Y, 2M, 2C, and 2K by the processes described above. Is formed.

  Below the four process units 2Y, 2M, 2C, and 2K, a transfer unit 60 as transfer means is disposed. This transfer unit 60 is shown in the drawing by rotationally driving any one of the rollers while contacting an intermediate transfer belt, which is an image carrier stretched by a plurality of rollers, with the photoreceptors 3Y, 3M, 3C, and 3K. Move endlessly clockwise. As a result, primary transfer nips for Y, M, C, and K in which the photoreceptors 3Y, 3M, 3C, and 3K contact the intermediate transfer belt 61 are formed.

  In the vicinity of the primary transfer nips for Y, M, C, and K, the intermediate transfer belt 61 is moved to the photoreceptors 3Y, M, C, and K by primary transfer rollers 62Y, 62M, 62C, and 62K disposed inside the belt loop. Pressing toward K. A primary transfer bias is applied to the primary transfer rollers 62Y, 62M, 62C, 62K by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoreceptors 3Y, 3M, 3C, and 3K toward the intermediate transfer belt 61 is formed in the primary transfer nips for Y, M, C, and K. Has been.

  In the drawing, a toner image is formed on each of the primary transfer nips on the front surface of the intermediate transfer belt 61 that sequentially passes through the primary transfer nips for Y, M, C, and K with endless movement in the clockwise direction. Are sequentially superimposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface of the intermediate transfer belt 61.

  A secondary transfer counter roller 72 as a contact member is disposed below the intermediate transfer belt 61 in the drawing, and the belt is placed at a place where the intermediate transfer belt 61 is wound around the secondary transfer roller 68. A secondary transfer nip is formed in contact with the surface. As a result, a secondary transfer nip is formed in which the front surface of the intermediate transfer belt 61 and the secondary transfer counter roller 72 abut.

  In the loop of the intermediate transfer belt 61, a secondary transfer roller 68 as a transfer bias member is subjected to secondary transfer having the same polarity as the normal charging polarity of the toner (negative polarity in this example) by a secondary transfer power supply circuit (not shown). A bias is applied. On the other hand, the secondary transfer counter roller 72 that forms the secondary transfer nip while being in contact with the front surface of the belt is grounded. As a result, a secondary transfer electric field is formed in the secondary transfer nip for electrostatically moving negative toner from the belt side toward the secondary transfer counter roller 72 side.

  On the right side of the secondary transfer nip in the drawing, the above-described registration roller pair (not shown) is disposed, and the recording paper sandwiched between the rollers can be synchronized with the four-color toner image on the intermediate transfer belt 61. Send to the secondary transfer nip. In the secondary transfer nip, the four-color toner image on the intermediate transfer belt 61 is secondarily transferred onto the recording paper under the influence of the secondary transfer electric field and the nip pressure, and becomes a full color image combined with the white color of the recording paper.

  The transfer residual toner that has not been transferred to the recording paper at the secondary transfer nip adheres to the front surface of the intermediate transfer belt 61 that has passed through the secondary transfer nip. This transfer residual toner is cleaned by a belt cleaning device 75 in contact with the intermediate transfer belt 61.

  In FIG. 1 described above, the recording paper that has passed through the secondary transfer nip is separated from the intermediate transfer belt 61 and transferred to the transport belt unit 39. The transport belt unit 39 moves the endless transport belt 40 endlessly in the counterclockwise direction in the figure by the rotational drive of the drive roller 41 while being stretched by the drive roller 41 and the driven roller 42. The recording paper delivered from the secondary transfer nip is conveyed along with the endless movement of the belt while being held on the belt upper tension surface, and delivered to the fixing unit 43.

  In the fixing unit 43, a fixing belt stretched by a driving roller and a heating roller containing a heat generation source is moved endlessly in the clockwise direction in the drawing as the driving roller is driven to rotate. The pressure roller 45 disposed below the fixing belt is brought into contact with the lower tension surface of the fixing belt to form a fixing nip. The recording paper received by the fixing unit 43 is pressed or heated in the fixing nip, whereby the full-color image on the surface is fixed. Then, it is sent out from the fixing unit 43 toward the switching claw 49.

  The switching claw 49 is swung by a solenoid (not shown), and the recording paper conveyance path is switched between the paper discharge path and the reversing path with the swing. When the paper discharge path is selected by the switching claw 49, the recording paper fed out from the fixing unit 43 passes through the paper discharge path and the paper discharge roller pair 47 and is then discharged to the outside of the apparatus and discharged to the paper discharge tray. 48 is stacked.

  A switchback device 46 is disposed below the fixing unit 43 and the conveyor belt unit 39. When the switchback path is selected by the switching claw 49, the recording paper fed out from the fixing unit 43 is turned upside down via the reversing path and then sent to the switchback device 46. Then, the image enters the secondary transfer transfer nip again, and the secondary transfer processing and fixing processing of the image are performed on the other surface.

  The scanner 160 fixed on the printer unit 1 has a fixed reading unit 161 and a moving reading unit 162 as reading means for reading an image of a document (not shown). A fixed reading unit 161 having a light source, a reflection mirror, an image reading sensor such as a CCD, and the like is disposed immediately below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner 160 so as to contact the document. . Then, when the document conveyed by the ADF 170 passes over the first contact glass, the light emitted from the light source is sequentially reflected by the document surface and is received by the image reading sensor via the plurality of reflection mirrors. Thus, the original is scanned without moving the optical system including the light source and the reflecting mirror.

  On the other hand, the moving reading unit 162 is disposed directly below a second contact glass (not shown) fixed to the upper wall of the casing of the scanner 160 so as to come into contact with the document, and an optical system including a light source, a reflection mirror, and the like. It can be moved in the left-right direction in the figure. Then, in the process of moving the optical system from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the second contact glass and then passed through a plurality of reflecting mirrors. The image is received by an image reading sensor fixed to the scanner body. Accordingly, the original is scanned while moving the optical system.

  In FIG. 3 described above, in the stirring unit 5Y of the developing device 4Y, when the developer is stirred and transported by the transport screw (6Y, 7Y), the developer is increased by friction with the transport screw or friction between the magnetic carriers. Warm up. When such a temperature rise occurs, the charge amount of the toner in the developer is lowered and the developing ability is lowered. Further, the toner may be melted to lower the developing ability, or may be fixed to various members and adversely affect the developing property. In recent years, in order to reduce the fixing energy, a tendency to adopt a low-melting-point toner having a lowered glass transition point of the toner has been increased, and it is easy to cause melting of the toner due to a temperature rise in the developing device.

  In order to suppress melting of this type of toner, an image forming apparatus provided with a cooling device for cooling the developing device by a liquid cooling method is known. FIG. 10 is a schematic configuration diagram illustrating an example of a conventional cooling device. In the figure, a cooling device 500 includes a heat receiving portion 501, a reserve tank 502, a circulation pump 503, a heat radiating portion 504, a cooling fan 505, a pipe member 506, and the like. The heat receiving unit 501, the reserve tank 502, the circulation pump 503, and the heat radiating unit 504 are sequentially connected by a pipe member 506. Further, the heat radiating part 504 and the heat receiving part 501 are also connected by the pipe member 506. Their interior is filled with a cooling liquid as a cooling medium. When the circulation pump 503 is activated, the coolant in the circulation pump 503 returns to the circulation pump 503 via the heat radiating unit 504, the heat receiving unit 501, and the reserve tank 502 in this order.

  The heat receiving portion 501 is urged toward the developing device 510 by the coil spring 508, thereby being brought into close contact with the casing side surface of the developing device 510. The casing of the heat receiving unit 501 is made of a metal material having high thermal conductivity such as aluminum, and cools the developing device 510 by conducting heat from the developing device 510 to itself. With this cooling, the temperature of the housing of the heat receiving unit 501 rises, but this heat is quickly taken away by the coolant passing through the heat receiving unit 501. For this reason, the temperature of the housing of the heat receiving part 501 is maintained below a certain temperature. The coolant that has been heated when passing through the heat receiving unit 501 passes through the reserve tank 502 and the circulation pump 503 and then enters the heat radiating unit 504.

  As shown in FIG. 11, the heat receiving unit 501 is closely attached to the side surface of the developing device casing in the process unit 509 in which the developing device 510 and the photosensitive member are integrated as one unit.

  In FIG. 10 described above, the housing of the heat radiating unit 504 is also made of a metal material having a high thermal conductivity such as aluminum, like the heat receiving unit 501. In addition, a plurality of heat radiation plates made of a metal material are erected on a part of the housing of the heat radiation part 504, thereby increasing the surface area of the heat radiation part 504. The coolant that has passed through the circulation pump 503 and reached the heat radiating section 504 is deprived of heat by the housing of the heat radiating section 504. Thereby, the coolant is cooled and the temperature of the housing of the heat radiating unit 504 is raised. The heat transferred from the coolant to the housing of the heat radiating unit 504 is quickly released from the plurality of heat radiating plates described above to the outside air. In order to promote this discharge, the cooling fan 505 blows air toward the plurality of heat radiating plates.

  In the cooling device 500 having such a configuration, the cooling device having a constant heat capacity that is much larger than that of air is used as a cooling medium, and the heat taken from the developing device 510 is efficiently sent to the heat radiating unit 504, so that the developing device 510 can be improved. It is possible to cool down. In addition, when water is used as the coolant, the constant volume heat capacity is 3000 times or more that of air.

  However, as the casing of the developing device 510, it is common to use a casing that is only molded by a general molding method for the purpose of cost reduction. Such a casing is inferior in surface smoothness as compared with a case in which a smoothing process is performed by cutting or the like after molding, and generates a wavy surface waviness having a wavelength of about several centimeters to several tens of centimeters. The height difference between the valley portion and the peak portion of the surface undulation is about 1 [mm]. If there is such a height difference, as shown in FIG. 12, a gap is formed between the valley portion and the heat receiving portion 501 in the surface undulation of the casing of the developing device 510, and both can be adhered well. Disappear. In the illustrated example, a high thermal conductivity sheet 507 for absorbing a certain gap is interposed between the casing surface of the developing device 510 and the heat receiving unit 501, but the above-described 1 [ The gap is still generated because the height difference of [mm] is larger. If the thickness of the sheet is increased to about several [mm], it is possible to absorb the gap. However, it becomes difficult to propagate heat from the casing to the heat receiving unit 501 satisfactorily.

Next, a characteristic configuration of the copier according to the embodiment will be described.
FIG. 4 is a configuration diagram showing the cooling device 80 of the copying machine according to the embodiment and the developing devices 4Y, 4M, 4C, and 4K for each color that are to be cooled. The cooling device 80 includes heat receiving units 81Y, 81M, 81Y, 81Y, 81M, 81C, and 81C as heat receiving portions that are individually in close contact with the casing side surfaces of the developing devices 4Y, M, C, and K for Y, M, C, and K and receive heat from the casing side surfaces. C, K. Further, a reserve tank 85, a circulation pump 86, a heat radiating portion 87, a cooling fan 88, a pipe member 89 and the like are also provided. The heat receiving units 81 </ b> Y, 81 </ b> M, C, and K for each color, the reserve tank 85, the circulation pump 86, and the heat radiating unit 87 are sequentially connected by a pipe member 89. Further, the heat radiating portion 87 and the Y heat receiving unit 81Y are also connected by a pipe member 89. Each member and the circulation pump 86 are filled with a cooling medium (not shown). When the circulation pump 86 is activated, the cooling medium in the circulation pump 86 returns to the circulation pump 86 through the heat radiating portion 87, the heat receiving units 81Y, M, C, and K of each color, and the reserve tank 85 sequentially.

  The casings of the developing devices 4Y, 4M, 4C, and 4K for each color are made of aluminum having high thermal conductivity. It is obtained by casting molten aluminum in a mold, and its side surface remains a solid surface after molding, and surface smoothing by cutting or the like is not performed.

  Each color heat receiving unit 81Y, M, C, K in the cooling device 80 is made of a metal material having a high thermal conductivity such as aluminum, and develops by conducting heat from the developing devices 4Y, M, C, K to itself. The devices 4Y, M, C, and K are cooled. With this cooling, the heat receiving unit 81 rises in temperature, but this heat is quickly taken away by the cooling medium passing through the heat receiving unit. For this reason, the temperature of the heat receiving units 81Y, 81M, 81C, 81K is maintained below a certain temperature. The cooling medium whose temperature has risen when passing through the heat receiving units 81Y, 81M, 81C, 81C, 81K passes through the reserve tank 85 and the circulation pump 86 and then reaches the heat radiating portion 87.

  Similarly to the heat receiving units 81Y, 81M, 81C, and 81K, the housing of the heat radiating portion 87 is also made of a metal material having high thermal conductivity such as aluminum. In addition, a plurality of heat radiating plates made of a metal material are erected on a part of the housing of the heat radiating portion 87, thereby increasing the surface area of the heat radiating portion 87. The cooling medium that has passed through the circulation pump 86 and reaches the heat radiating portion 87 is deprived of heat by the housing of the heat radiating portion 87. As a result, the cooling medium is cooled and the temperature of the housing of the heat radiating portion 87 is raised. The heat transferred from the cooling medium to the housing of the heat radiating section 87 is quickly released from the plurality of heat radiating plates described above to the outside air. In order to promote this discharge, the cooling fan 88 blows air toward the plurality of heat radiating plates.

  Examples of the cooling medium include a liquid cooling medium, a gel cooling medium, and a gaseous cooling medium. Among these, the liquid cooling medium is excellent in terms of thermal conductivity, fluidity, and transportability. As a liquid cooling medium, water is the main component, and propylene glycol or ethylene glycol is added to lower the freezing temperature, or a rust inhibitor (for example, a phosphate-based substance to prevent rust of metal components) : Potassium phosphate, inorganic potassium salt, etc.) can be exemplified.

  Each color heat receiving unit 81Y, 81M, 81C, 81K includes three divided heat receiving units. Taking the heat receiving unit 81Y for Y as an example, this includes a first divided heat receiving portion 82Y, a second divided heat receiving portion 83Y, and a third divided heat receiving portion 84Y. These divided heat receiving portions are arranged in the developer transport direction (up and down direction on the paper surface in FIG. 4 = unit longitudinal direction) with respect to the casing side surface of the developing device 4Y. Similarly, the heat receiving units 81M, C, and K of the other colors also have the same first divided heat receiving portions 82M, C, and K, second divided heat receiving portions 83M, C, and K, and third divided heat receiving portions 84M, C, and K. It has.

  FIG. 5 is an enlarged configuration diagram showing the developing device 4Y for Y and its peripheral configuration in the copying machine of the embodiment. In the drawing, a heat conductive sheet 91 is adhered to the surface of the first divided heat receiving portion 82Y for Y of the cooling device that faces the developing device 4Y for Y. The first divided heat receiving portion 82Y is urged toward the casing side surface of the developing device 4Y for Y by a coil spring 92 as an urging means supported by a support plate 93 fixed to the copier body housing. ing. As a result, the heat transfer sheet 91 is in close contact with the side surface of the casing. In the figure, only the first divided heat receiving portion 82Y is shown among the three divided heat receiving portions in the Y heat receiving unit (81Y), but the second divided heat receiving portion (83Y) and the third divided heat receiving portion ( 84Y) is also biased toward the developing device 4Y by a dedicated coil spring. Similarly, in the other color heat receiving units (81M, C, K), the three divided heat receiving portions are respectively urged toward the developing devices (4M, C, K) by dedicated coil springs.

  FIG. 6 is an enlarged plan sectional view showing the developing device 4Y for Y and the heat receiving unit 81Y for Y. As shown in the drawing, surface waviness having exactly the same wavelength and height difference as the conventional developing device 510 shown in FIG. 12 is generated on the casing side surface of the developing device 4Y. In the conventional configuration shown in FIG. 12, as described above, a gap is generated between the heat receiving portion formed in a horizontally long shape and the valley portion of the surface waviness. On the other hand, in the copying machine according to the embodiment, as shown in FIG. 6, different divided heat receiving portions are opposed to the surface waviness crests and troughs on the casing side surface of the developing device 4Y. Specifically, a surface undulation in which peaks, valleys, and peaks appear in order from the left side to the right side in the drawing is generated on the casing side surface of the developing device 4Y. And the 1st division | segmentation heat receiving part 82Y is made to oppose among the three division | segmentation heat receiving parts with respect to the peak part of the left side in the figure in a surface wave | undulation. Further, the second divided heat receiving portion 83Y is opposed to the valley portion in the surface undulation. Further, the third divided heat receiving portion 84Y is opposed to the left ridge portion in the figure in the surface undulation. Of these three divided heat receiving portions, the second divided heat receiving portion 83Y that faces the valley portion of the surface undulation is developed more than the first divided heat receiving portion 82Y and the third divided heat receiving portion 84Y that are in close contact with the peak portion. If it can be brought close to the casing side surface of the device 4Y, it can be satisfactorily adhered to the valley portion of the surface undulation. Therefore, in the copying machine according to the embodiment, the tube member 89 for sending and receiving the cooling medium to each of the three divided heat receiving portions is not deformable and has high rigidity that cannot be deformed as in the related art. What consists of a flexible tube which has flexibility is connected. In such a configuration, the second divided heat receiving portion 83 </ b> Y facing the valley of the surface undulation on the side surface of the casing of the developing device 4 </ b> Y is bent by freely bending the pipe member 89 according to the position of each divided heat receiving portion. The first divided heat receiving portion 82Y and the third divided heat receiving portion 84Y that are in close contact with the portion can be separated and moved to be in good contact with the valley portion. Therefore, as is apparent from the comparison with FIG. 12, it is possible to suppress poor adhesion between the casing side surface of the developing device 4 </ b> Y and the heat receiving unit 81 via the heat conductive sheet 91 compared to the conventional case.

  The adhesion between the heat receiving unit 81Y for Y and the casing side surface of the developing device 4Y for Y has been described, but the heat receiving units 81M, C, K of other colors and the casing side surfaces of the developing devices 4M, C, K are described. Similarly, the adhesiveness is improved as compared with the conventional case.

  In addition, it is possible to cope with surface waviness having a relatively long wavelength as shown in FIG. 6 by using three divided heat receiving parts instead of one horizontally long heat receiving part. It is impossible to deal with minute irregularities such as μm to several mm. Therefore, with respect to such minute unevenness, the formation of a gap is avoided by deforming the heat conductive sheet 91 interposed between the casing side surface and the divided heat receiving portion in accordance with the uneven pattern.

  In the embodiment, the entire longitudinal direction region of the pipe member 89 used in the cooling device 80 is made of a flexible material made of a flexible tube, but the entire longitudinal direction region is made flexible. There is no necessity. As long as each of the divided heat receiving parts can be moved independently in the urging direction in units of several mm, some of them may be highly rigid. Moreover, as a flexible tube, the thing made from rubber | gum or resin can be illustrated.

  When the process unit is replaced, the urging by the coil spring 92 that urges each divided heat receiving portion of the heat receiving unit is released, and then the process unit is removed. Then, after mounting a new process unit, the coil spring 92 is urged again to bring each divided heat receiving portion into close contact with the developing device of the new process unit.

  FIG. 7 is an enlarged side view showing the developing device 4Y for Y and the heat receiving unit 81Y for Y. Each of the three divided heat receiving portions (82Y, 83Y, 84Y) in the Y heat receiving unit 81Y has a hollow inside, and the hollow is partitioned into an upper space and a lower space in the vertical direction. A flexible tube member 89 is connected to the upper space of the first divided heat receiving portion 82Y from the left side in the drawing. In addition, the upper space of the first divided heat receiving portion 82Y and the upper space of the second divided heat receiving portion 83Y are connected by a flexible tube member 89 disposed between the two spaces. Furthermore, the upper space of the second divided heat receiving portion 83Y and the upper space of the third divided heat receiving portion 84Y are connected by a flexible tube member 89 disposed between the two spaces. With the above connection, the upper space of the first divided heat receiving portion 82Y, the upper space of the second divided heat receiving portion 83Y, and the upper space of the third divided heat receiving portion 84Y are communicated in that order. Then, the cooling medium fed into the upper space of the first divided heat receiving portion 82Y sequentially passes through the upper space of the second divided heat receiving portion 83Y and the upper space of the third divided heat receiving portion 84Y, and is divided inside each of them. Take heat away from the heat receiver.

  A pipe member 89 disposed on the left side of the third divided heat receiving portion 84Y connects the upper space of the third divided heat receiving portion 84Y and the lower space of the third divided heat receiving portion 84Y. Thereby, the cooling medium that has passed through the upper space of the third divided heat receiving portion 84Y enters the lower space of the third divided heat receiving portion 84Y.

  The lower space of the third divided heat receiving portion 84Y and the lower space of the second divided heat receiving portion 83Y are connected by a flexible tube member 89 disposed between the two spaces. Further, the lower space of the second divided heat receiving portion 83Y and the lower space of the first divided heat receiving portion 82Y are connected by a flexible tube member 89 disposed between the two spaces. With the above connection, the lower space of the third divided heat receiving portion 84Y, the lower space of the second divided heat receiving portion 83Y, and the lower space of the first divided heat receiving portion 82Y communicate in that order. Then, the cooling medium fed into the lower space of the third divided heat receiving portion 84Y sequentially passes through the lower space of the second divided heat receiving portion 83Y and the lower space of the first divided heat receiving portion 82Y, and is divided inside each of them. Take heat away from the heat receiver.

  The cooling medium involved in cooling the Y developing device 4Y as described above exits from the lower space of the first divided heat receiving portion 82Y and then enters the M heat receiving unit 81M as shown in FIG. To do. In the M heat receiving unit 81M, similarly to the Y heat receiving unit 81Y, the upper space of the first divided heat receiving portion 82M, the upper space of the second divided heat receiving portion 83M, and the upper portion of the third divided heat receiving portion 84M. The space, the lower space of the third divided heat receiving portion 84M, the lower space of the second divided heat receiving portion 83M, and the lower space of the first divided heat receiving portion 82M are sequentially passed. Thereafter, the C heat receiving unit 81C and the K heat receiving unit 81K sequentially follow the same path, and then reach the reserve tank 85.

  In the copying machine according to the embodiment, the three divided heat receiving portions are individually brought into close contact with the casing side surface of one developing device, but the number of the divided heat receiving portions is not limited to three. . About the number of division | segmentation heat receiving parts, it is desirable to determine suitably according to the wavelength of the surface waviness estimated based on a casing dimension, a shaping | molding precision, etc.

  Next, an example in which a more characteristic configuration is added to the copying machine according to the embodiment will be described. FIG. 8 is an enlarged side view showing the developing device 4Y for Y and the heat receiving unit 81Y for Y in the copying machine according to the embodiment. The internal space of the three divided heat receiving portions (82Y, 83Y, 84Y) in the Y heat receiving unit 81Y is partitioned into a left space and a right space in the horizontal direction. In any space, the flexible tube member 89 is connected from the lower side in the vertical direction and from the upper side.

  Since the three divided heat receiving portions (82Y, 83Y, 84Y) are arranged in the horizontal direction, the upper side surface and the lower side surface are non-facing surfaces in which the divided heat receiving portions do not face each other. Yes. As described above, in the copying machine according to the embodiment, the flexible tube member 89 is connected to the non-opposing surface with respect to the other divided heat receiving portions for each of the three divided heat receiving portions. In such a configuration, it is possible to connect the pipe member 89 to each divided heat receiving part without interposing the pipe member 89 between the divided heat receiving parts. Thereby, as can be seen from the comparison with FIG. 7 which is an aspect of the embodiment, the gap between the divided heat receiving portions is significantly reduced, and the size of the divided heat receiving portion is increased accordingly, thereby further improving the cooling performance. Can be increased.

  Of the three divided heat receiving units, the cooling medium is first supplied to the left space of the first divided heat receiving unit 82Y. This supply is performed by the pipe member 89 connected to the left space from the lower side in the vertical direction. The cooling medium supplied to the left space is discharged from the left space by the pipe member 89 connected to the left space from the upper side in the vertical direction, and then from the upper side in the vertical direction to the right space of the second divided heat receiving portion 83Y. enter in. And after discharging | emitting toward the perpendicular direction lower side from the same right space, it approachs from the perpendicular direction lower side with respect to the left space of the 3rd division | segmentation heat receiving part 84Y. Then, after discharging | emitting toward the vertical direction upper side from the left space, it approachs from the vertical direction upper side with respect to the right space of the 3rd division | segmentation heat receiving part 84Y. Next, after being discharged from the right space toward the lower side in the vertical direction, it enters the left space of the second divided heat receiving portion 83Y from the lower side in the vertical direction. Further, after being discharged from the left space toward the upper side in the vertical direction, it enters the right space of the first divided heat receiving portion 82Y from the upper side in the vertical direction. Then, it is discharged from the right space toward the lower side in the vertical direction and passes through all the spaces of the heat receiving unit 81Y.

  FIG. 9 is an enlarged side view showing a developing device 4Y for Y and a heat receiving unit 81Y for Y in a modification of the copier according to the embodiment. Also in this heat receiving unit 81Y, as in the embodiment, each of the divided heat receiving portions is a flexible tube on the side surface on the upper side in the vertical direction, which is a non-facing surface with the other divided heat receiving portions, and on the lower side surface. The member 89 is connected. However, the method of scooping the pipe member 89 is different from the embodiment. Specifically, in the modification, the left space of the first divided heat receiving portion 82Y → the right space → the left space of the second divided heat receiving portion 83Y → the right space → the left space of the third divided heat receiving portion 84Y → the right space. In addition, the pipe member 89 is turned so that the cooling medium enters the six spaces arranged side by side sequentially from the left side to the right side in the drawing. Compared with the embodiment, since the connection mode of the pipe member 89 is simple, the scooping operation can be simplified.

  So far, the example in which the developing device as the cooled object is cooled by the cooling device 80 according to the present invention has been described. However, the present invention can also be applied to a mode of cooling the cooled object different from the developing device. Is possible. In addition, the present invention can be applied not only to an electrophotographic image forming apparatus but also to an image forming apparatus using another method such as an ink jet method.

  As described above, in the copying machine according to the embodiment, the image forming unit that forms an image on the recording paper P that is a recording member by the process units 2Y, M, C, and K of each color, the optical writing unit 50, the transfer unit 60, and the like. It is composed. Then, the heat receiving part that receives heat in close contact with the developing devices 4Y, 4M, 4C, and 4K of each color that is a cooled object, the heat radiating part 87 that releases heat, and the inside of the heat receiving part and the inside of the heat radiating part 87 are circulated. The following characteristic configuration is adopted for a cooling device 80 as a cooling means including a cooling medium to be transported and a pipe member 89 connecting the heat receiving unit and the heat radiating unit 87 for transporting the cooling medium. Yes. That is, as the heat receiving part, the developing devices 4Y, M, C, and K are provided with a first divided heat receiving part, a second divided heat receiving part, and a third divided heat receiving part that are configured to be in close contact with each other. A flexible member is used as the pipe member 89 for sending and receiving the cooling medium to the divided heat receiving portions. In such a configuration, as described above, it is possible to suppress poor adhesion between the developing devices 4Y, 4M, 4C, and 4K and the heat receiving unit, as compared with the related art.

  Further, in the copying machine according to the embodiment, the divided heat receiving portions are made flexible so that the cooling medium is transmitted and received between the first, second, and third divided heat receiving portions for each color. The pipe members 89 are connected. In such a configuration, since it becomes possible to send the cooling medium after sequentially passing through the three divided heat receiving portions to the one heat radiating portion 87, the three divided heat receiving portions are individually corresponded to each other. Compared with the case where a dedicated heat radiating portion is provided, the structure can be simplified, reduced in size, and reduced in cost.

  Further, in the copying machine according to the embodiment or the modified example, the flexible tube member 89 is provided for each of the first, second, and third divided heat receiving portions, and the non-facing surface with the other divided heat receiving portions. Connected to. In such a configuration, as described above, the cooling performance is greatly reduced by reducing the gap between the divided heat receiving portions significantly compared to the case of connecting to the opposing surface, and by increasing the size of the divided heat receiving portions accordingly. Can be further enhanced.

  In the copying machine according to the embodiment, the first, second, and third divided heat receiving portions are individually biased toward the casing side surface of the developing device, and the coil springs 92 as a plurality of urging means are attached to closely contact each other. Provided. In such a configuration, the process unit on which the developing device is mounted can be attached to and detached from the main body independently of the cooling device 80 by releasing the urging by the urging means or restarting the urging as necessary. Can do.

  In the copier according to the embodiment, coil springs 92 are used as a plurality of urging means for individually urging each divided heat receiving portion. In such a configuration, even if the divided heat receiving portion is inclined to follow the curved shape of the casing side surface of the developing device, the coil spring 92 is buckled following the curved shape, so that the divided heat receiving portion can be satisfactorily applied to the curved surface. Can be pressed.

  In the copying machine according to the embodiment, as an image forming unit, a photosensitive member as a latent image carrier that carries a latent image, and a developing device as a developing unit that develops the latent image carried on the surface of the photosensitive member with toner. And a transfer unit 60 that is a transfer means for transferring a toner image obtained by development from a photoreceptor to a recording sheet, and a plurality of divided heat receiving portions are arranged along the toner conveyance direction in the developing device. It is arranged so that different portions in the toner conveying direction in the developing device are cooled by the divided heat receiving portions. In such a configuration, the toner whose temperature is increased by the rubbing accompanying the conveyance can be satisfactorily cooled by the plurality of divided heat receiving portions arranged along the conveyance direction.

P: Recording paper (recording member)
2Y, M, C, K: Process unit (part of image forming means)
3Y, M, C, K: photoconductor (latent image carrier)
4Y, M, C, K: Developing device (developing means)
50: Optical writing unit (part of image forming means)
60: Transfer unit (part of image forming means)
80: Cooling device (cooling means)
81Y, M, C, K: heat receiving unit 82Y, M, C, K: first divided heat receiving part (one of a plurality of heat receiving parts)
83Y, M, C, K: Second divided heat receiving part (one of a plurality of heat receiving parts)
84Y, M, C, K: Third divided heat receiving part (one of a plurality of heat receiving parts)
87: Heat radiation part 89: Tube member 92: Coil spring

JP 2005-164927 A

Claims (5)

In order to form an image on a recording member, a latent image carrier that carries a latent image, a developing unit that develops the latent image carried on the surface of the latent image with toner, and a toner image obtained by development are carried on the latent image carrier. An image forming unit having a transfer unit for transferring the image from a body to a recording member; a cooling unit for cooling the developing unit; a heat receiving unit that is in close contact with the developing unit and receives the heat of the developing unit; The cooling means includes a heat radiating part to be discharged, a cooling medium that is circulated and conveyed through the heat receiving part and the heat radiating part, and a pipe member that connects the heat receiving part and the heat radiating part for conveying the cooling medium. In the image forming apparatus provided in
As the heat receiving part, a plurality of parts for cooling different portions in the developing means are provided,
The plurality of heat receiving portions are arranged side by side along the toner transport direction in the developing means, and different portions of the developing means in the toner transport direction are cooled by the heat receiving portions,
An image forming apparatus characterized in that a flexible member is used as the tube member for transmitting and receiving the cooling medium to and from the plurality of heat receiving portions. The image forming apparatus according to claim 1 .
An image forming apparatus, wherein the heat receiving portions are connected by the flexible tube member so as to transmit and receive the cooling medium between the plurality of heat receiving portions. The image forming apparatus according to claim 2 .
An image forming apparatus, wherein the flexible tube member is connected to each of the plurality of heat receiving portions on a non-facing surface with respect to another heat receiving portion. The image forming apparatus according to any one of claims 1 to 3 ,
An image forming apparatus, comprising: a plurality of urging means for individually urging and closely contacting the plurality of heat receiving portions toward the body to be cooled. The image forming apparatus according to claim 4 .
An image forming apparatus characterized in that a coil spring is used as each of the plurality of biasing means.

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