JP5240595B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In an image forming apparatus, it is known that heat is generated at various locations such as a writing device, a fixing device and a developing device provided in the apparatus, a drive motor that rotates and drives an image carrier, and the temperature inside the apparatus is increased. It has been.

  For example, in a developing device, when a developer agitating / conveying member that stirs and conveys the developer in the developing device is driven, frictional heat caused by friction between the developer agitating / conveying member and the developer, The temperature in the apparatus is raised by frictional heat due to rubbing. In addition, the friction heat generated by the friction between the developer regulating member and the developer that regulates the layer thickness of the developer carried on the developer carrying body before the developer is transported to the developing area, and the developer regulating member. The temperature in the apparatus is increased by frictional heat generated by rubbing between the developers during the regulation.

  When the temperature in the apparatus rises, the charge amount of the toner decreases, the toner adhesion amount increases, and a predetermined image density cannot be obtained. Further, the toner may melt due to the temperature rise and adhere to the developer regulating member, the developer carrier, the image carrier, etc., and a streaky abnormal image may be generated in the image. In particular, in recent years, when a toner having a low melting temperature is used in order to reduce the fixing energy, an abnormal image or the like due to the fixing of the toner tends to occur.

  Therefore, conventionally, a cooling fan or the like generates an air flow around the temperature rise location inside the apparatus to cool the temperature rise location, thereby preventing the temperature inside the device from rising excessively. However, under the usage conditions of the apparatus, such as continuous operation for 24 hours, the temperature cooling inside the apparatus could not be sufficiently suppressed by the air cooling using the cooling fan.

  Patent Documents 1 and 2 describe an image forming apparatus using a liquid cooling method in which a liquid is circulated to cool a temperature rise portion. Since the liquid cooling method can cool more efficiently than the air cooling method, the temperature rise inside the device can be suppressed efficiently, and the temperature rise inside the device can be well suppressed even under usage conditions such as continuous operation for 24 hours. Can do.

FIG. 15 is a schematic view of a liquid cooling type cooling apparatus.
As shown in the figure, the liquid cooling type cooling apparatus includes a cooling pipe 83 containing cooling liquid, a radiator 81a and a cooling fan 81b, and cooling means 81 for cooling the cooling liquid in the cooling pipe, and the temperature of the apparatus. A heat receiving portion 82 provided in the rising portion 300 and from which the cooling liquid takes heat of the temperature rising portion 300; and a pump 84 serving as a conveying means for circulating the cooling liquid in the cooling pipe between the cooling means 81 and the heat receiving portion 82; It has. The cooling liquid in the cooling pipe cooled by the cooling means 81 flows to the heat receiving portion 82 and takes the heat of the temperature rising portion 300 to cool the temperature rising portion 300. The cooling liquid in the cooling pipe heated by the heat receiving portion 82 flows to the radiator 81a, and the heat of the cooling liquid is radiated and cooled by the cooling fan 81b. Then, the cooled liquid in the cooling pipe is sent again toward the heat receiving portion by the pump 84.

  If a cooling device as shown in FIG. 15 is provided at each of a plurality of temperature rise points in the apparatus, the cost increases. Therefore, in the image forming apparatus described in Patent Documents 1 and 2, corresponding to the plurality of temperature rise points. A plurality of heat receiving portions provided are connected in parallel or connected in series so that the temperature rising portion of the cooling target in the apparatus is cooled by one cooling means.

  However, when a plurality of heat receiving portions are connected in parallel, since the pipe branches, the flow rate of the coolant flowing through each heat receiving portion is lowered, and the cooling efficiency at the temperature rising portion is lowered. This is because the flow rate of the coolant is small, and the temperature of the coolant rises to a temperature near the temperature rise location with a small amount of heat. As a result, it becomes impossible to sufficiently remove the heat at the temperature rising portion, and the cooling efficiency is lowered. For this reason, it is necessary to lower the temperature of the coolant flowing through each heat receiving part in consideration of the decrease in cooling efficiency due to the decrease in flow rate. Since the flow rate of the coolant flowing through the cooling means is larger than the flow rate of the coolant flowing through each heat receiving portion, the coolant is difficult to cool. Therefore, unless the cooling efficiency is increased more than necessary by the cooling means, the temperature of the coolant flowing through each heat receiving portion cannot be lowered to a temperature that takes into account the decrease in cooling efficiency due to the decrease in flow rate. As described above, since it is necessary to increase the cooling efficiency of the cooling means more than necessary, there is a problem in that the number of rotations of the cooling fan is increased, the wind noise of the cooling fan is increased, and noise is generated. In addition, in order to increase the cooling efficiency of the coolant, it is necessary to widen the heat dissipation area of the radiator, which increases the size of the radiator.

  On the other hand, when a plurality of heat receiving units are connected in series, the temperature of the coolant rises every time the heat receiving units pass. For this reason, in order to keep all the temperature rising points below a predetermined temperature, the cooling liquid flowing to the most downstream heat receiving part with the cooling means as a base point is used to increase the temperature of the temperature rising part provided in the heat receiving part. The temperature must be able to be suppressed. For this purpose, the temperature of the cooling liquid flowing out from the cooling means needs to be considerably lowered in consideration of the temperature rise of the cooling liquid by the heat receiving section upstream from the most downstream heat receiving section, and the cooling liquid flows out from the cooling means. The difference between the temperature of the coolant and the temperature of the coolant that has returned to the cooling means through the plurality of heat receiving portions increases. As a result, it is necessary to increase the cooling efficiency of the cooling liquid of the cooling means, which increases the number of rotations of the cooling fan, increasing the wind noise of the cooling fan and causing noise. In addition, in order to increase the cooling efficiency of the coolant of the radiator, it is necessary to increase the heat radiation area of the radiator, which increases the size of the radiator.

  As described above, in order to suppress the temperature rise of all the temperature rise points of the cooling target in the apparatus with one cooling means, even when the plurality of heat receiving portions are arranged in series or in parallel, the cooling means There is a need to increase the cooling efficiency, and there arises a problem that noise due to wind noise of the cooling fan is increased and the cooling means is enlarged.

  The present invention has been made in view of the above-described problems, and its object is to better suppress the temperature rise than air cooling, and to provide cooling that includes a conveying means and a cooling means at each of a plurality of temperature rise points. Compared to a device that is equipped with a device, the temperature of a plurality of temperature rise points can be suppressed at a low cost, and the size and noise of the cooling means can be increased compared to a device that suppresses a plurality of temperature rise points with a single cooling means. It is to provide an image forming apparatus capable of suppressing the above.

In order to achieve the above object, the invention of claim 1 is provided with cooling means for cooling a cooling liquid for cooling a plurality of cooled parts, and each cooled part, and the cooling liquid is provided in the cooled parts. A plurality of heat receiving portions that receive the heat of the liquid, and a cooling liquid that is included in the cooling fluid, and the plurality of heat receiving portions are connected in parallel or in series, and the cooling liquid that is included is circulated through the heat receiving portion and the cooling means. In an image forming apparatus comprising a tube and a conveying means for conveying the cooling liquid in the cooling pipe to each heat receiving part, the image forming apparatus includes a plurality of the cooling means, and each cooling means is provided in at least one of the cooled parts. Correspondingly, control means for controlling each cooling means based on the operating state of the image forming apparatus is provided.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the cooling efficiency of the cooling unit is made different between an operation start of the cooled portion and a predetermined time after the operation. Is.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a plurality of the heat receiving units and a plurality of the cooling units are connected in series, and the temperature of at least one of the cooled units is less than a threshold value. Is higher, the cooling efficiency of the portion to be cooled on the upstream side in the coolant transport direction than the portion to be cooled is increased.
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 cooling efficiency of the cooling unit is lower when forming a monochrome image than when forming a color image. It is a feature.

According to the present invention, by suppressing the temperature rise of a plurality of cooled parts by the liquid cooling method, the temperature rise of the cooled parts can be suppressed more favorably than when the temperature rise of the cooled parts is suppressed by air cooling. be able to.
Further, since the cooling pipe is piped so that the cooling liquid circulates through the plurality of heat receiving parts, the cooling liquid can flow to each heat receiving part by one transport means. Therefore, as compared with a case where a cooling device as shown in FIG. 15 is provided in each of the plurality of cooled parts, the number of conveying means can be reduced, and the cost of the device can be reduced.
In addition, a plurality of cooling means are provided, and each cooling means is made to correspond to at least one cooled part, and based on the operating state of the image forming apparatus, the temperature rise of the cooled part is suppressed by the corresponding cooling means. As compared with the one that suppresses the temperature rise of all the cooled parts by one cooling means, the number of the cooled parts that suppress the temperature rise by one cooling means can be reduced. In this way, since one cooling means can reduce the number of cooled parts that suppress the temperature rise, even if the cooling efficiency of each cooling means is low, the temperature rise of all the cooled parts can be improved satisfactorily. Can be suppressed. As a result, it is possible to use a small-sized cooling unit that does not have a large heat radiation area and does not have a very high cooling efficiency as compared with a single cooling unit that corresponds to all the parts to be cooled. It becomes possible to reduce the size. In addition, when the cooling means has a cooling fan, the number of rotations of the cooling fan can be suppressed as compared with a structure in which all the cooled parts are cooled by one cooling means, and the wind noise of the cooling fan is reduced. Noise due to can be suppressed.

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. 2 is an enlarged configuration diagram illustrating a process unit for Y in the printer unit. 1 is a schematic configuration diagram illustrating a cooling device according to Embodiment 1. FIG. The schematic block diagram of a heat receiving part. FIG. 3 is a schematic perspective view showing a state in which a heat receiving unit is fixed to a developing device. FIG. 3 is a schematic configuration diagram illustrating another configuration of the cooling device according to the first embodiment. The graph which shows the relationship between the air flow rate and thermal resistance in a common radiator. FIG. 6 is a control flow diagram of the cooling device according to the second embodiment. FIG. 6 is a schematic configuration diagram illustrating another configuration example of the cooling device according to the second embodiment. FIG. 10 is a control sequence diagram of a cooling fan of each cooling unit when a full-color image is formed by the cooling device according to the third embodiment. FIG. 10 is a control sequence diagram of the cooling fan of each cooling unit when a monochrome image is formed by the cooling device according to the third embodiment. FIG. 6 is a schematic configuration diagram of a cooling device according to a fourth embodiment. The schematic block diagram which shows other embodiment of a cooling device. The schematic block diagram of the cooling device of a liquid cooling system.

Hereinafter, a first embodiment of a copier that forms an image by an electrophotographic method will be described as an image forming apparatus to which the present invention is applied.
First, the basic configuration of the copier according to the first embodiment will be described. FIG. 1 is a schematic configuration diagram showing a copying machine according to the first 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 photoreceptor 3Y into a Y toner image in addition to the photoreceptor 3Y. 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. The transfer unit 60 rotates in the clockwise direction in the drawing by rotating 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 in the direction. 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 photosensitive members 3YY, M, C, and K by primary transfer rollers 62Y, M, C, and K 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.

Next, the cooling device that is a feature of the present embodiment will be described based on Examples 1 to 4.
Many members and units that generate heat during operation, such as a fixing unit 43, a power supply unit (not shown), an optical writing unit 50, and developing devices 4Y to 4K, are installed in the copying machine. On the other hand, there are members that dislike heat such as the photoconductors 3Y to 3K and the developing devices 4Y to 4K around the member that generates heat. This is because, in a high temperature atmosphere, the characteristics of the toner and the toner in the developing device change and a good image cannot be obtained. Therefore, the temperature rises around the photosensitive members 3Y to 3K and the developing devices 4Y to 4K Must be cooled.

[Example 1]
FIG. 2 is a schematic configuration diagram of the cooling device 80 according to the first embodiment.
As shown in the figure, the cooling device 80 is provided in correspondence with each developing device, and heat receiving portions 82Y to 82K that are in contact with the developing devices 4Y to 4K that are the temperature rising portions and receive the heat from the developing device. The cooling means 81Y to 81K for cooling the liquid for cooling the developing devices 4Y to 4K, the heat receiving portions 82Y to 82K are connected in series, the cooling pipe 83 containing the cooling liquid, and the cooling liquid in the cooling pipe And a cooling pump 84 serving as a conveying means for circulation.

  The coolant is mainly composed of water, and propylene glycol or ethylene glycol is added to lower the freezing temperature of the coolant, or a rust inhibitor (for example, a phosphate-based substance to prevent rusting of metal components) : Potassium phosphate salt, inorganic potassium salt, etc.).

  The cooling means 81Y to 81K are configured by radiators 81aY to 81aK and cooling fans 81bY to 81bK as heat radiating means, and the radiators 81aY to 81aK are connected to a flow path formed of a highly heat conductive member and the flow path. And a fin formed of a good heat conductive member. As the radiators 81aY to 81aK, corrugated fin types can be suitably used, and the radiators 81aY to 81aK are arranged outside the exterior material of the copying machine. The cooling units 81Y to 81K generate air currents by cooling fans 81bY to 81bK around the flow paths and fins of the radiators 81aY to 81aK and cool them by forced convection heat conduction. By disposing outside the exterior material of the copying machine, outside air having a temperature lower than that inside the apparatus can be applied to the flow path and fins of the radiator, and the cooling efficiency of the radiator can be increased. Further, the cooling means may be disposed inside the exterior material, and a duct may be provided so that relatively low temperature air or outside air in the apparatus is taken in and applied to the radiator.

FIG. 5 is a schematic configuration diagram of the heat receiving portion 82Y, and FIG. 6 is a schematic perspective view showing the heat receiving portion 82Y fixed to the developing device 4Y.
As shown in FIG. 5, the heat receiving portion 82Y is provided with a flow path 82bY formed of a good heat conductive member inside a case 82aY formed of a good heat conductive member. Then, as shown in FIG. 6, it contacts the outer peripheral surface of the case of the developing device 4Y.
The other heat receiving portions 82C to 82K have the same configuration.

The developing devices 4Y to 4K are provided with temperature detection sensors 91Y to 91K as temperature detection means.
The cooling fans 81bY to 81bK are connected to a control unit 200 as control means, and the control unit 200 determines the rotation speed of each cooling fan based on the temperature of the developing device detected by the temperature detection sensors 91Y to 91K. And cooling efficiency of the radiators 81aY to 81aK is controlled. Specifically, if the temperature of the developing device 4 is equal to or higher than a predetermined value as a result of detection by the temperature detection sensor 91, the number of rotations of the cooling fan 81b is increased, the cooling efficiency of the radiator 81a is increased, and the temperature of the coolant is increased. Lower.

  The cooling liquid sent out by the cooling pump 84 is cooled by the Y radiator 81Y corresponding to the Y developing device 4Y. The cooling liquid cooled by the Y radiator 81Y flows into the Y heat receiving portion 82Y and moves in the pipe line of the Y heat receiving portion 82Y, while taking the heat of the developing device 4Y and causing the developing device 4Y to move. cool. The coolant whose temperature has risen in the Y heat receiving portion 82Y is cooled by the M radiator 81M corresponding to the M developing device 4M, and the M developing device 4M is cooled by the M heat receiving portion 82M. The coolant whose temperature has risen in the M heat receiving portion 82 is cooled by the C radiator 81C corresponding to the C developing device 4C, and the C heat receiving portion 82C cools the C developing device 4C. The coolant whose temperature has risen in the C heat receiving portion 82C is cooled by the K radiator 81K corresponding to the K developing device 4K, and the K developing device 4K is cooled by the K heat receiving portion 82K. Then, the cooling liquid which is again conveyed to the Y radiator 81Y by the cooling pump 84 and has risen in temperature by the K heat receiving portion 82 is cooled by the Y radiator 81Y.

In the cooling device 80 according to the first exemplary embodiment, cooling units 81Y to 81K are provided corresponding to the developing devices which are portions where the temperature rises. The cooling means corresponding to the developing device 4 is disposed adjacent to the upstream side of the corresponding developing device in the coolant movement direction. As a result, the coolant flowing from the cooling means does not flow to the non-corresponding heat receiving portion until it flows to the corresponding heat receiving portion of the developing device. As a result, the temperature of the developing device corresponding to the cooling means does not rise due to the heat of the developing device that does not correspond to the cooling liquid. Therefore, since the cooling means does not need to cool the cooling liquid in consideration of the temperature rise of the cooling liquid by the developing device which does not correspond to this, the number of rotations of the cooling fan of the cooling means can be reduced, and the fan motor that rotates the cooling fan The rotation noise and the wind noise of the cooling fan can be reduced, and the apparatus noise can be suppressed. Further, the coolant can be sufficiently cooled without using a radiator having a large heat radiation area and high cooling efficiency, and the cooling means can be reduced in size.
Further, since the cooling efficiency of the cooling means corresponding to the developing device is controlled based on the temperature of the developing device, it is possible to prevent the developing device from being excessively cooled, and dew condensation occurs in the developing device. It is possible to prevent the toner from aggregating with water droplets due to condensation within the developing device.
In addition, since each developing device is cooled by liquid cooling, each developing device can be cooled more efficiently than the case where each developing device is cooled by air cooling, and the temperature rise of the device can be sufficiently suppressed.

In the above description, the cooling means 81Y to 81K and the heat receiving portions 82Y to 82K are connected in series, but may be arranged in parallel as shown in FIG.
When arranged in parallel in this way, the flow rate flowing through each branched cooling pipe is small. For this reason, each cooling means can cool the cooling liquid to a temperature sufficient to cool the temperature rising portion without increasing the cooling efficiency so much. Therefore, the number of rotations of the cooling fan of the cooling means can be reduced, the rotation sound of the fan motor that rotates the cooling fan and the wind noise of the cooling fan can be reduced, and the apparatus noise can be suppressed. Further, the coolant can be sufficiently cooled without using a radiator having a large heat radiation area and high cooling efficiency, and the cooling means can be reduced in size.
Moreover, when arrange | positioning in parallel, dispersion | variation arises in the flow volume of the cooling fluid which flows into each heat receiving part 82Y-82K, and the cooling efficiency in each heat receiving part differs. However, in FIG. 7, since the cooling means is provided corresponding to each developing device, the cooling liquid flowing in the heat receiving part is increased from the others by increasing the cooling efficiency of the cooling means at a place where the flow rate of the cooling liquid is small. cool. Thereby, the temperature rise of the developing device corresponding to the heat receiving part with a small flow rate of the cooling liquid can be suppressed well. On the other hand, where the flow rate of the coolant is large, the cooling efficiency of the cooling means is lowered than the others, and the temperature of the coolant flowing in the heat receiving part is raised higher than others, so that it corresponds to the heat receiving part through which a lot of coolant flows. It is possible to prevent the developing device from being cooled too much.

[Example 2]
Next, Example 2 will be described.
A developing device close to a heat source such as a fixing device, a power supply device, or a drive motor is more likely to rise in temperature than other developing devices. For this reason, the cooling means corresponding to the developing device whose temperature is likely to rise more than other developing devices needs to increase the cooling efficiency as compared with the other developing devices.
FIG. 8 is a graph showing the relationship between air flow rate and thermal resistance in a general radiator. The thermal resistance is defined as (Tw−Ta) / Q [, where Ta [° C.] is the inflow air temperature, Tw [° C.] is the inflow coolant temperature, and Q [W] is the amount of heat exchanged between the air and the coolant. [° C./W]. That is, the smaller the thermal resistance, the higher the cooling efficiency of the radiator.
As shown in FIG. 8, when the air flow rate increases, the cooling efficiency of the radiator increases. However, as the air flow rate increases, the rate of decrease in thermal resistance decreases. That is, as the number of rotations of the cooling fan increases, the cooling efficiency of the radiator does not increase so much. For this reason, the number of rotations of the cooling fan corresponding to the developing device whose temperature is likely to rise more than that of the other developing device is much higher than the number of rotations of the cooling fan corresponding to the other developing device. Become. As a result, there arises a problem that the wind noise of the cooling fan corresponding to the developing device whose temperature rises more easily than the other developing devices and the noise of the driving motor of the cooling fan become louder.

  Therefore, in the second embodiment, a developing device that is more likely to rise in temperature than the other developing devices by using a cooling unit corresponding to the developing device that is more likely to rise in temperature than other developing devices and other cooling means. The cooling is controlled.

The configuration of the cooling device in the second embodiment is the same as that of the cooling device shown in FIG.
FIG. 9 is a control flow in the cooling device of the second embodiment. In the second embodiment, a developing device for K will be described as an example.
As shown in FIG. 9, first, when the K developing device 4K is operated, the control unit 200 detects the temperature in the K developing device with the temperature detection sensor 91K, and detects the detected developer temperature (developing device internal temperature). Is a first threshold value (S1). When the value is equal to or less than the first threshold (NO in S1), the control unit 200 sets the K cooling fan 81bK to the initial rotational speed (S5).
On the other hand, when the developer temperature (developing device internal temperature) exceeds the first threshold (YES in S1), the control unit 200 determines whether the developer temperature (developing device temperature) exceeds the second threshold. Is checked (S2). If the second threshold value is exceeded (YES in S2), it is checked whether the developer temperature (developing device temperature) exceeds the third threshold value (S3). If the developer temperature (developing device temperature) exceeds the third threshold (YES in S3), the toner in the developing device may melt and cause uneven development, which is a malfunction of the device. And the operation of the developing device for K is stopped (S4).

On the other hand, when the developer temperature (developing device temperature) is equal to or lower than the third threshold value (NO in S3), the rotational speed of the K cooling fan 81bK is set to a rotational speed increased by 10% from the initial rotational speed. The rotational speed of the C cooling fan 81bC for cooling the C radiator 81aC on the upstream side in the coolant movement direction with respect to the K radiator 81K is set to a rotational speed increased by 10% from the initial rotational speed (S9). Thereby, when the developer temperature exceeds the second threshold value and is equal to or lower than the third threshold value, the cooling efficiency of the K radiator 81aK and the C radiator 81aC is increased. By increasing the cooling efficiency of the C radiator 81aC, the temperature of the coolant flowing out of the C radiator 81aC is lowered. Since the calorific value of the C developing device 4C does not change, the temperature of the coolant that has passed through the C heat receiving portion 82C is lowered by increasing the cooling efficiency of the C radiator 81aC. As a result, since the coolant having a low temperature flows into the K radiator 81aK, the coolant flowing out from the K radiator 81bK as compared with the case where only the K cooling fan 81bK is increased by 10% compared to the initial rotational speed. The temperature becomes lower. Therefore, a coolant having a low temperature can be caused to flow through the K heat receiving portion 82K, and the K developing device 4K can be cooled well. As a result of increasing the cooling efficiency of the C radiator 81aC, the C developing device 4C is cooled as compared with the case where the C developing device 4C is driven at the initial rotational speed of the cooling fan 81bC. It won't get chilled.
If the second threshold value is not exceeded (NO in S2), the rotational speed of the K cooling fan 81bK is set to a rotational speed increased by 10% from the initial rotational speed (S6). Further, when the rotational speed of the C cooling fan 81bC is set to a rotational speed that is increased by 10 [%] from the initial rotational speed and is not rotating at the initial rotational speed (NO in S7), the C cooling fan The rotational speed of 81bC is returned to the initial rotational speed (S8).

  As described above, in the second embodiment, when the temperature of the K developing device 4K rises, the K cooling device 81K corresponding to the K developing device 4K does not respond only, but rather than the K cooling device 81K. The temperature rise of the K developing device is suppressed by using the C cooling means and the K cooling means corresponding to the C developing device 4C on the upstream side in the coolant movement direction.

  In the case where the K developing device 4K increases the heat generation amount by 3 [W] compared to other developing devices, and the temperature rise of the K developing device 4K is suppressed only by the K cooling means 81K. As in Example 2, when the temperature rise of the K developing device 4K exceeds the second threshold, the K cooling means 81K and the C cooling means 81C suppress the temperature rise of the K developing device 4K. Then, the rotational speed of the cooling fan 81bK for K was examined. As a result, when only the K cooling means 81K was used, the rotational speed of the K cooling fan 81bK was maximum and increased by 30% compared to the initial rotational speed. On the other hand, in Example 2, the K cooling unit 81K and the C cooling unit 81C each increased by 10% with respect to the initial rotational speed, and the temperature increase of the K developing device 4K could be suppressed satisfactorily. As a result, noise such as wind noise from the cooling fan 81bK and power consumption can be suppressed as compared with the case where the temperature rise of the K developing device 4K is suppressed only by the K cooling means.

In the above description, when the first threshold is exceeded, the rotational speed of the K cooling fan 81bK is increased by 10% of the initial rotational speed, and when the second threshold is exceeded, the K and C cooling fans 81bK are increased. The rotational speed of 81 cK is increased by 10 [%] of the initial rotational speed, but this value may be set as appropriate based on the amount of heat generated by the K developing device 4K.
Further, in the above description, the control is made different according to the three threshold values of the first threshold value, the second threshold value, and the third threshold value, but the threshold value may be set more finely and controlled. For example, when the first threshold value is exceeded, the rotational speed of the K cooling fan 81bK is increased by 5% with respect to the initial rotational speed, and when the second threshold value is exceeded, the rotational speed of the K cooling fan 81bK is increased to the initial rotational speed. Is increased by 10%. When the third threshold value is exceeded, the rotational speed of the C cooling fan 81bC is increased by 5% with respect to the initial rotational speed, and when the fourth threshold value is exceeded, the rotational speed of the C cooling fan 81bK is increased to the initial rotational speed. Alternatively, the number of rotations of the cooling fan may be controlled to increase stepwise so as to increase by 10%. Further, the rotation speed of the K cooling fan 81bK is continuously controlled according to the temperature of the K developing device 4K until the first threshold is exceeded, and the rotation of the C cooling fan 81bC is exceeded until the second threshold is exceeded. The number may be continuously controlled according to the temperature of the K developing device 4K.

  Further, in the above description, when the second threshold value is exceeded, the C cooling means 81C provided on the upstream side of the K cooling means 81K is used. For example, the C cooling fan 81bC is initially rotated. Control may be performed so that the number of rotations of the cooling fan 81bM of the M cooling means upstream of the C cooling means 81C is increased by 5 [%] with respect to the number. Further, when the second threshold value is exceeded, the number of rotations of the cooling fan 81bC of the C cooling means 81C provided on the upstream side of the K cooling means 81K is increased. You may control to increase the rotation speed of the cooling fan 81bM of the cooling means 81M. Of course, when the second threshold value is exceeded, the rotational speeds of the cooling fans 81bY, 81bM, 81bC of the three cooling means Y, M, C may be controlled to increase by a predetermined amount.

  The same control may be performed for cooling the developing devices 4Y, 4M, and 4C for Y, M, and C. That is, when the temperature of the C developing device 4C exceeds the first threshold, the cooling fan 81bC of the C cooling means is increased by 10 [%] with respect to the initial rotational speed, and the temperature of the C developing device 4C is increased. Exceeds the second threshold, the cooling fan 81bM of the M cooling means 81M is increased by 10 [%] with respect to the initial rotational speed. For example, when the temperature of the K developing device 4K exceeds the second threshold value, the temperature of the C developing device 4C exceeds the first threshold value, and the cooling fan 81bC of the C cooling means 81C has already reached the initial rotational speed. On the other hand, when it is increased by 10 [%], the rotational speed of the cooling fan 81bM of the M cooling means 81M further upstream than the C cooling means 81C is increased by 10 [%] with respect to the initial rotational speed. The cooling fan 81bK of the K cooling means 81K may be increased by 20 [%] with respect to the initial rotational speed.

  In the above description, the temperature sensor controls the driving of the cooling fan of each cooling unit based on the temperature in the developing device. However, as shown in FIG. 10, the cooling for detecting the temperature of the coolant that has passed through the heat receiving portion. Cooling liquid temperature detection sensors 191Y to 191K serving as liquid temperature detection means are provided, and the control unit 200 estimates the temperature of the developing device based on the temperature of the cooling liquid that has passed through the heat receiving unit detected by the cooling liquid temperature detection sensors 191Y to 191K. The driving of the cooling fans 81bY to 81aY of the cooling units 81Y to 81K may be controlled based on the estimated temperature of the developing device.

[Example 3]
Next, Example 3 will be described.
In the third embodiment, the temperature detection sensor is eliminated, and the relationship between the temperature of the developing device and the operating time is examined in advance by experiments, and the temperature of the developing device is estimated based on the operating time of the developing device. The cooling fans 81bY to 81bK of the cooling units 81Y to 81K are controlled.
FIG. 11 is a control sequence diagram of the cooling fans 81bY to 81bK of the cooling units during full-color image formation. In the figure, the vertical axis represents the number of rotations of the cooling fan, and the horizontal axis represents time. FIG. 11 is a control sequence diagram when the M color developing device 4M is affected by the heat generated from the other units and the temperature rise is larger than that of the other developing devices.
As shown in the drawing, when the copying machine operates the Y, M, C, and K developing devices to form a full color image, the cooling fans 81bY to 81bK of the cooling means for Y, M, C, and K are set to the initial rotational speed. Rotate with The rotational speeds of the cooling fans 81bY to 81bK of the respective cooling means are as follows: the initial rotational speed of the Y cooling fan 81bY is R1-1, the initial rotational speed of the M cooling fan 81bM is R2-1, and the C cooling fan 81bC. R3-1 = R3-1 = R4-1 <R2-1 where R3-1 is the initial rotation speed and R4-1 is the initial rotation speed of the cooling fan 81bK for K. That is, in the third embodiment, since the temperature rise of the M developing device 4M is larger than that of the other developing devices, the initial rotational speed R2-1 of the M cooling fan 81bM is set higher than the initial rotational speed of the other cooling fans. It is getting bigger.

  When the M developing device 4M is continuously operated for T1 seconds or more, it is estimated that the temperature of the M developing device 4M exceeds the second threshold value, so that the Y cooling means 81Y upstream of the M cooling means 81M The rotational speed of the cooling fan 81bY is increased from the initial rotational speed R1-1 to R1-2. As described above, also in Example 3, when the temperature of the M developing device 4M becomes higher than the threshold value, the cooling efficiency of the Y cooling means upstream of the M cooling means is increased, and the M developing is performed. By suppressing the temperature rise of the device 4M, noise such as wind noise from the cooling fan and power consumption can be suppressed as compared with the case where only the cooling means for M is used.

  When the formation of the full-color image is completed and the operation of the Y, M, C, and K developing devices is stopped, the rotational speeds of the Y, M, C, and K cooling fans 81bY to 81bK are decreased. The rotational speed of each cooling fan at this time is such that the initial rotational speed of the Y cooling fan 81bY is R1-3, the initial rotational speed of the M cooling fan 81bM is R2-3, and the C cooling fan 81bC is When the initial rotational speed is R3-3 and the initial rotational speed of the K cooling fan 81bK is R4-3, R1-3 = R3-3 = R4-3 <R2-3. This is because the M developing device is affected by heat from other units, and therefore, when the number of rotations of the M cooling fan 81bM is the same as that of the other cooling fans, the temperature is higher than that of the other developing devices. Get higher. Therefore, the number of rotations of the M cooling fan 81bM is set higher than the number of rotations of the other cooling fans, the cooling efficiency of the M radiator 81aM is made higher than that of the other radiators, and the M developing device is replaced with another developing device. The temperature of the developing device for M is made to be about the same as the temperature of other developing devices.

  When T3 seconds have elapsed after the operation of the developing device is completed, the rotational speed of the cooling fan for M 81bM is decreased from R2-3 to R2-4, and the rotational speed of the cooling fan for M 81bM is rotated by the rotation of other cooling fans. Set to the same number of rotations after the end. This is because the temperature of the unit that affects the heat of the M developing device 4M is lowered and the M developing device 4M is not heated, and the temperature drop of the M developing device 4M is the same as the other developing devices. Therefore, if the rotation speed of the M cooling fan 81bM remains R2-3, the temperature of the M developing device 4M becomes lower than that of the other developing units. Therefore, by setting the rotation speed of the M cooling fan 81bM to be the same as the rotation speed of the other cooling fans, the temperature of the M developing device 4M can be set to the same level as the temperatures of the other developing devices.

  Then, when T2 seconds have elapsed after the operation of the developing device is finished, the driving of the Y, M, C, and K cooling fans is stopped.

Next, drive control of the cooling fans of the cooling units 81Y to 81K when forming a monochrome image will be described.
FIG. 12 is a control sequence diagram of the cooling fans of the cooling units 81Y to 81K when a monochrome image is formed.
In the case of a monochrome image, the Y, M, and C developing devices do not generate heat because they are not in operation, and only the K developing device generates heat by stirring the developer. The M developing device is more greatly affected by heat from other units than the Y and C developing devices, and rises in temperature compared to the Y and C developing devices.
For this reason, the magnitude relationship between the initial rotational speeds of the cooling fans of the respective cooling units at the start of monochrome image formation is R1′−1 = R3′−1 <R2′−1 <R4′-1. R1′-1 is the initial rotational speed of the Y cooling fan 81bY, R2′-1 is the initial rotational speed of the M cooling fan 81bM, and R3′-1 is the C cooling fan 81bC. This is the initial rotational speed, and R4'-1 is the initial rotational speed of the K cooling fan 81bK.
Further, as can be seen from FIG. 12, the initial rotational speed of each cooling fan is set lower than the initial rotational speed at the time of full-color image formation. This is because the Y, M, and C developing devices are not in operation, and frictional heat and the like are not generated when the developer is agitated. Therefore, the heat generated by the Y, M, and C developing devices is larger than that during full color image formation. The temperature rises moderately because it becomes lower. Further, the K developing device is hardly affected by the heat of the C developing device adjacent to the K developing device, so that the temperature rise is moderate as compared to the time of full color image formation. For this reason, when each cooling fan is rotated at the same initial rotational speed as that at the time of full-color image formation, each developing device may be cooled too much to cause condensation. Therefore, the initial rotational speed of each cooling fan at the time of monochrome image formation is made smaller than the initial rotational speed at the time of full-color image formation.

  During monochrome image formation, each cooling fan rotates at a constant speed, and after the monochrome image formation is completed, the rotation speed of each cooling fan is set to R1′-2, R2′-2, R3′-2, R4′-2. To drop. At this time, the rotation speed of each cooling fan is R1'-2 = R2'-2 = R3'-2 = R4'-2.

[Example 4]
Next, Example 4 will be described.
FIG. 13 is a schematic configuration diagram of a cooling device according to the fourth embodiment.
In the first to third embodiments, the cooling means is provided corresponding to each of the developing devices that are the temperature rise portions. However, in the cooling device of the fourth embodiment, the cooling means corresponds to two developing devices. It has been made.

The cooling fan drive control in the cooling device of the fourth embodiment is performed by, for example, the K developing device and the M developing device affected by the heat from other units, and the C developing device and the Y developing device. If the temperature rises more easily, the following control is performed.
First, when each developing device is operated, the control unit causes the cooling fan 81bYM of the cooling unit 81YM corresponding to the Y developing device and the M developing device and the cooling unit 81CK corresponding to the C developing device and the K developing device. The cooling fan 81bCK is rotated at the initial rotational speed.

When the temperature of one of the C developing device and the K developing device is affected by the heat of the other unit and exceeds the first threshold, the rotation speed of the cooling fan 81bCK of the cooling unit 81CK is initially rotated. Increase 10% from the number.
Further, when the temperatures of both the C developing unit and the K developing unit exceed the first threshold, the rotational speed of the cooling fan 81bYM of the cooling means 81YM upstream of the cooling means 81CK is set to the initial rotational speed. Increase by 10%. When one of the temperatures of both the C developing unit and the K developing device exceeds the first threshold, the rotation speed of the cooling fan 81bYM of the cooling unit 81YM is set. Return to the initial speed. Then, when the temperature of one of the C developing unit and the K developing unit exceeds the first threshold value and both of the temperatures become equal to or lower than the first threshold value, the rotational speed of the cooling fan 81bCK of the cooling unit 81CK Return to the initial speed.

  Also in the fourth embodiment, as in the third embodiment, the temperatures of the C developing unit and the K developing device are estimated from the operating time of each developing device, and the number of rotations of the cooling fan 81bYM of the cooling unit 81YM and the cooling unit 81CK are estimated. The number of rotations of the cooling fan 81bCK may be controlled. Further, the temperature of the coolant that has passed through the heat receiving portion is detected by the coolant temperature detection sensor, and the temperature of the developing device is estimated from the detection result of the coolant temperature sensor, and the rotation of the cooling fan 81bYM of the cooling means 81YM is rotated. The number and the number of rotations of the cooling fan 81bCK of the cooling means 81CK may be controlled. The same control may be performed for cooling the Y developing device and the M developing device.

In the first to fourth embodiments, the cooling device that cools the developing device is described as the temperature rise portion of the apparatus. However, as shown in FIG. 14, the power supply device, the drive unit, and the fixing device are used as the temperature rise location in the apparatus. Etc. may be cooled.
The cooling device includes a first heat receiving portion 184 attached to a temperature rising portion of the power supply device, a second heat receiving portion 185 attached to the temperature rising portion of the drive unit, and a third heat receiving portion attached to the temperature rising portion of the fixing device. 186.
In addition, a first cooling unit 181 corresponding to a temperature rise portion of the power supply device is provided upstream of the first heat receiving unit 184, and between the first heat receiving unit 184 and the second heat receiving unit 185. The second cooling means 182 corresponding to the temperature rising part of the drive unit is provided, and the third cooling corresponding to the temperature rising part of the fixing device is provided between the second heat receiving part 185 and the third heat receiving part 186. Means 183 are provided. The cooling pipe 188 containing the cooling liquid has the first cooling means 181, the first heat receiving part 184, the second cooling means 182, the second heat receiving part 185, the third cooling means 183, and the third heat receiving part with the pump 187 as a base point. They are connected in series in the order of 186.
A control unit (not shown) controls the number of rotations of the cooling fan 181b of the first cooling unit 181 based on the temperature of the temperature rising part of the power supply device, and the second cooling unit based on the temperature of the temperature rising part of the drive unit. The number of rotations of the cooling fan 182b of 182 is controlled, and the number of rotations of the cooling fan 183b of the third cooling means 183 is controlled based on the temperature of the temperature rising portion of the fixing device.
The control unit (not shown) also rotates the number of rotations of the cooling fan 182b of the second cooling unit 182 corresponding to the drive unit when the temperature of the temperature rise portion of the fixing device (for example, the case of the fixing device) exceeds a threshold value. To increase the cooling efficiency of the second cooling means 182. As a result, the temperature of the coolant flowing through the third heat receiving portion 186 is lowered, and the temperature rise at the temperature rise portion of the fixing device can be suppressed. As a result, it is possible to suppress an increase in the internal temperature of the apparatus and an increase in the temperature of the developing device and the photoconductor disposed near the fixing device.

  In the above description, the cooling means is composed of a radiator and a cooling fan. However, the cooling means may be composed of a Peltier element, a Peltier element cooling fin serving as a heat dissipation means, and a cooling fan.

As described above, the cooling device according to the present embodiment includes a cooling unit that cools the cooling liquid for cooling the developing devices for Y, M, C, and K that are a plurality of temperature rise points in the image forming apparatus, and each developing device. A heat receiving portion that receives the heat of the developing device and a cooling liquid, and a plurality of heat receiving portions are connected in parallel or in series, and the included cooling liquid circulates between the heat receiving portion and the cooling means. The cooling pipes thus piped and a pump which is a conveying means for conveying the cooling liquid in the cooling pipes to the plurality of heat receiving portions.
In addition, a plurality of cooling units are provided, each cooling unit is associated with at least one developing device, and a control unit is provided as a control unit that controls each cooling unit based on the temperature of the corresponding developing device.
With this configuration, it is possible to reduce the number of developing devices for one cooling unit to suppress the temperature rise compared to one cooling unit that suppresses the temperature rise of all the developing devices. As a result, even if the cooling efficiency of each cooling unit is low, it is possible to satisfactorily suppress the temperature rise of all the developing devices. As a result, it is possible to use a small radiator that does not have a large heat dissipation area and does not have a very high cooling efficiency, compared to a single cooling means that suppresses the temperature rise of all the developing devices, and the cooling device can be downsized. Is possible. Moreover, the rotation speed of a cooling fan can be suppressed and the noise by the wind noise of a cooling fan can be suppressed.
Further, since each developing device is cooled by the liquid cooling method, each developing device can be cooled more efficiently than the one cooled by the air cooling method.
In addition, since a plurality of heat receiving units are connected in parallel or in series and the cooling liquid is conveyed to each heat receiving unit by a single pump, a cooling system including a pump, a heat receiving unit, a cooling unit, and a cooling pipe is provided for each developing device. The device can be made cheaper than a device provided with the device.

  In addition, the cooling pipe is configured so that the cooling liquid cooled by the cooling means does not flow to the heat receiving portion provided at the non-corresponding temperature rising portion until it flows to the heat receiving portion provided at the corresponding temperature rising portion. doing. With this configuration, the cooling liquid cooled to a temperature sufficient to suppress the temperature rise of the developing device corresponding to the heat receiving unit by the cooling unit can be supplied to each heat receiving unit. Therefore, the temperature rise portion can be cooled well.

  Further, in the second embodiment, in the cooling device in which the heat receiving portions are connected in series, when the developing device reaches a predetermined temperature or higher, the cooling liquid moving direction upstream side of the cooling means corresponding to the temperature rising portion. Control is performed to increase the cooling efficiency of the cooling means. As a result, even if a certain developing device has a higher temperature than other developing devices, and it is difficult to obtain a sufficient cooling effect only by the cooling means corresponding to this developing device, the coolant can move with a sufficient margin for cooling. By increasing the cooling efficiency of the cooling means on the upstream side in the direction, the developing device having a higher temperature than the other developing devices can be cooled well.

  In particular, when the temperature rise location corresponding to the cooling means becomes equal to or higher than the first temperature, control is performed to increase the cooling efficiency of the cooling means, and the temperature rise location corresponding to a certain cooling means is higher than the first temperature. When the temperature exceeds the second temperature, the cooling efficiency of the cooling means upstream of the cooling liquid moving direction is higher than that of the cooling means, so that only the cooling means corresponding to the developing device can provide a sufficient cooling effect. When it becomes difficult, the cooling efficiency of the cooling means on the upstream side in the coolant movement direction with a margin for cooling can be increased.

  In addition, each developing device is provided with a temperature detection sensor serving as a temperature detection means, and each cooling means is controlled based on the values of these temperature detection sensors, so that the temperature is reduced to a temperature necessary to suppress the temperature rise of the development device. The cooling liquid can be sent to a heat receiving portion provided in the developing device. Therefore, the coolant that has fallen to a temperature higher than necessary to suppress the temperature rise of the developing device is sent to the heat receiving part, the developing device is overcooled, or the temperature is lowered to a temperature necessary to suppress the temperature rise. It is possible to prevent the cooling liquid that is not flowing from flowing into the heat receiving portion and preventing the temperature rise of the developing device from being suppressed.

  Further, the temperature of each developing device may be estimated based on the elapsed time from the start of image formation by the image forming apparatus, and each cooling unit may be controlled based on the estimated temperature of each developing device. With this configuration, the temperature detection sensor can be eliminated, and the cooling liquid lowered to the temperature necessary to suppress the temperature rise of the developing device can be sent to the heat receiving unit provided in the developing device, thereby reducing the cost of the device. Can be made cheaper.

  In addition, a cooling liquid temperature detection sensor serving as a cooling liquid temperature detection means for detecting the temperature of the cooling liquid that has passed through the developing device is provided, and the temperature of each developing device is estimated based on the temperature of the cooling liquid. Each cooling means may be controlled based on the temperature of the apparatus. Even if comprised in this way, the cooling liquid reduced to the temperature required in order to suppress the temperature rise of a developing device can be sent to the heat receiving part provided in the developing device.

  In addition, the cooling means has a radiator as a heat radiating means for releasing the heat of the coolant and a cooling fan for cooling the radiator. Therefore, the cooling efficiency of the cooling means can be easily controlled by controlling the number of revolutions of the cooling fan. can do.

  In addition, the cooling device can suppress the melting of the toner in the developing device by suppressing the temperature rise of the plurality of developing devices.

  In addition, as shown in FIG. 12, the cooling unit corresponding to a developing device that is not in operation has a cooling efficiency that is lower than the cooling efficiency of the cooling means corresponding to the developing device that is in operation. It is possible to prevent the developing device that does not generate heat from being excessively cooled. As a result, it is possible to suppress the occurrence of condensation in the developing device that is not in operation.

  In addition, the cooling efficiency of the cooling means corresponding to the developing apparatus with a large amount of heat received is higher than the cooling efficiency of the other cooling means compared to other developing apparatuses, thereby increasing the temperature of the developing apparatus with a large amount of heat received. It can suppress well.

4Y, 4M, 4C, 4K: Development devices 81Y, 81M, 81C, 81K: Cooling means 82Y, 82M, 82C, 82K: Heat receiving section 83: Cooling pipe 84: Pump

JP 2006-171211 A JP 2007-206198 A

Claims (4)

A cooling means for cooling a coolant for cooling a plurality of parts to be cooled;
A plurality of heat receiving portions provided in each cooled portion, wherein the cooling liquid receives heat of the cooled portion;
A cooling pipe that encloses the cooling liquid, connects the plurality of heat receiving parts in parallel or in series, and is arranged so that the enclosing cooling liquid circulates between the heat receiving part and the cooling means;
In the image forming apparatus provided with a conveying means for conveying the cooling liquid in the cooling pipe to each heat receiving unit,
A plurality of the cooling means;
Each cooling means corresponds to at least one of the cooled parts,
An image forming apparatus comprising a control unit that controls each cooling unit based on an operating state of the image forming apparatus.   The image forming apparatus according to claim 1, wherein the cooling efficiency of the cooling unit is made different between an operation start of the cooled portion and a predetermined time after the operation. Connecting the plurality of heat receiving units and the plurality of cooling means in series;
3. The cooling efficiency of the cooled portion on the upstream side in the coolant transport direction with respect to the cooled portion when the temperature of at least one of the cooled portions is higher than a threshold value. The image forming apparatus described.   4. The image forming apparatus according to claim 1, wherein the cooling efficiency of the cooling unit is lower when forming a monochrome image than when forming a color image. 5.

Images