JP2012048160A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of effectively cooling an inside of a device body with a simple configuration.SOLUTION: An image forming device 100 comprises: a cooling device 102, supply means 104 to supply an inside of a device body 101 with external air with a temperature thereof is decreased while passing through the cooling device 102; and discharge means to discharge air inside the device body 101 to outside. The cooling device 102 and the supply means 104 are arranged at a higher level than an image forming section P in a gravity direction and the discharge means 105 is arranged at the same level as or a lower level than the image forming section P in the gravity direction.

Description

  The present invention relates to an image forming apparatus such as a copying machine and a printer using an electrophotographic system, and more particularly to an image forming apparatus having a supply / exhaust system for cooling the inside of the apparatus main body.

  In an electrophotographic image forming apparatus, a toner image formed on an electrophotographic photosensitive member (photosensitive member) in an image forming unit is transferred to the surface of a recording material such as recording paper directly or via an intermediate transfer member. . The toner image is fixed on the surface of the recording material when the recording material carrying the toner image is heated by a fixing device.

  The heat of the fixing device is dissipated not only to the recording material but also to the inside of the main body of the image forming apparatus, and this heat increases the temperature of the image forming unit. Further, in the developing device provided in the image forming unit, frictional heat is generated due to friction between the developer and the components of the developing device, and the developer self-heats. When the temperature in the developing device rises, the developer is hardened or the developer is rapidly deteriorated.

  Therefore, the image forming apparatus is often equipped with a means for cooling the image forming unit or the like. Generally, there are many things that take in outside air using a blower (fan) and cool the inside of the apparatus main body. On the other hand, by using a cooling device that uses heat of vaporization, such as a refrigerator or air conditioner, or a cooling device that uses the Peltier effect, the temperature inside the device body is lowered by taking air that is cooler than the outside air into the device body. Some will try.

  Patent Document 1 proposes that a cooler is installed on the side surface of the copying machine main body and cold air is introduced into the copying machine main body. Patent Document 2 proposes that compressed air is sent to a pipe-shaped frame by a compressor and fresh fresh air is taken into a plurality of components.

JP 58-217982 A JP-A-9-138629

  However, the conventional technique has the following problems.

  First, in the technique described in Patent Document 1, a cooler is installed on the side surface of the copying machine main body to introduce cold air into the copying machine main body. However, while the hot air in the copying machine main body is accumulated in the upper part in the direction of gravity, the cold air is heavy, so that there is a problem that the air in the copying machine main body cannot be cooled sufficiently. In order to cool the inside of the copier sufficiently, it is possible to increase the supply amount or supply pressure of the cool air. In that case, however, the size of the cooler, the cost increase, and the noise of the compressor and fan become problems. .

  Further, in the technique described in Patent Document 2, fresh outside air is introduced into the inside of the apparatus main body. However, when the temperature outside the apparatus main body is relatively high, the inside of the apparatus main body cannot be sufficiently cooled. There's a problem. In the technique described in Patent Document 2, compressed air is supplied to a plurality of locations in the machine by a compressor via a pipe frame of the frame. However, since the cross section of the pipe is limited and the air resistance is large, an increase in the size of the compressor is unavoidable in order to secure a necessary air volume, and the cost increases and the noise of the compressor becomes a problem.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of efficiently cooling the inside of the apparatus main body with a simple configuration.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to an image forming apparatus having an image forming unit for forming a toner image by an electrophotographic method inside the apparatus main body, a cooling device that takes in outside air and cools the outside air, and passes through the cooling device. And supplying air to the inside of the apparatus main body, and exhaust means for discharging the air inside the apparatus main body to the outside, the cooling device and the air supplying means Is arranged above the image forming unit in the gravitational direction, and the exhaust unit is arranged at substantially the same height as the image forming unit or below the image forming unit in the gravitational direction. The image forming apparatus.

  According to the present invention, the inside of the apparatus main body can be efficiently cooled with a simple configuration.

1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 1 is an external perspective view of a front surface of an image forming apparatus according to an embodiment of the present invention. 1 is an external perspective view of a rear surface of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a schematic configuration of a cooling device provided in an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a schematic configuration of a wastewater treatment apparatus included in an image forming apparatus according to an embodiment of the present invention. It is a flowchart figure of ON / OFF control of the cooling device which concerns on the other Example of this invention. It is a block diagram which shows the general | schematic control aspect of ON / OFF control of the cooling device which concerns on the other Example of this invention.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
1. FIG. 1 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 according to the present exemplary embodiment is a full color laser printer that can form a full color image using an electrophotographic method.

  Inside the apparatus main body 101 of the image forming apparatus 100, first, second, third, and fourth image forming units Py, Pm, Pc, and Pb are arranged as a plurality of image forming units. The first, second, third, and fourth image forming units Py, Pm, Pc, and Pb are toners that include yellow, magenta, cyan, and black toner images, respectively, that include charging, exposure, and development processes. It is formed by a photographic image forming process. The image forming apparatus 100 includes a control unit 19 as a control unit inside the apparatus main body 101. The control unit 19 includes a CPU as arithmetic processing means and a memory such as ROM or RAM as storage means. When the control unit 19 receives a print command signal output from an external device (not shown) such as a host computer, the control unit 19 performs first, second, third, and fourth according to an image formation control sequence stored in the memory. The image forming units Py, Pm, Pc, Pb and the like are operated.

  In this embodiment, the configurations and operations of the first, second, third, and fourth image forming units Py, Pm, Pc, and Pb have many common parts. Therefore, in the following, unless there is a particular distinction, the subscripts y, m, c, and b given to the reference numerals in the figure are omitted to indicate that they are elements provided for any color, I will explain it.

  The image forming unit P includes a drum-type electrophotographic photosensitive member, that is, a photosensitive drum 1 as an image carrier. The photosensitive drum 1 is rotationally driven at a predetermined peripheral speed (process speed) in the arrow direction (counterclockwise) in the figure. Around the photosensitive drum 1, the following units are arranged in order along the rotation direction. First, a charging roller 2 as a charging unit. Next, an exposure apparatus (laser scanner) 3 as an exposure unit. Next, there is a developing device 4 as a developing unit. Next, a drum cleaner 5 as a photosensitive member cleaning unit.

  Further, an endless belt-like intermediate transfer belt 7 serving as an intermediate transfer member is disposed so as to face the photosensitive drums 1y, 1m, 1c, and 1b of the image forming portions Py, Pm, Pc, and Pb. The intermediate transfer belt 7 is stretched around a driving roller 61, a driven roller 62, and a tension roller 63. The driving roller 61 rotates the peripheral direction corresponding to the rotational peripheral speed of each photosensitive drum 1 in the arrow direction (clockwise) in the figure. Driven at speed. On the inner peripheral surface side of the intermediate transfer belt 7, a primary transfer roller 8y, which is a primary transfer member as a primary transfer unit, faces the photosensitive drums 1y, 1m, 1c, and 1b with the intermediate transfer belt 7 interposed therebetween. 8m, 8c, and 8b are arranged, respectively. Each primary transfer roller 8 is pressed toward each photosensitive drum 1 via the intermediate transfer belt 7, and primary transfer portions (primary transfer nip portions) N1y, N1m, where each photosensitive drum 1 and the intermediate transfer belt 7 are in contact with each other. N1c and N1b are formed. On the outer peripheral surface side of the intermediate transfer belt 7, a secondary transfer roller 14 that is a secondary transfer member as a secondary transfer unit is disposed so as to face the driven roller 62. The secondary transfer roller 14 is pressed toward the driven roller 62 via the intermediate transfer belt 7, and a secondary transfer portion (secondary transfer nip portion) that is a contact portion between the intermediate transfer belt 7 and the secondary transfer roller 14. N2 is formed.

  The image forming operation in each image forming portion P will be described. First, the outer peripheral surface (front surface) of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the charger 2. Next, the surface of the charged photosensitive drum 1 is scanned and exposed by a laser beam generated by the exposure device 3 based on image information from an external device. Thereby, an electrostatic latent image (electrostatic image) corresponding to the image information is formed on the surface of the photosensitive drum 1. This electrostatic latent image is developed with toner by the developing device 4, and a toner image is formed on the surface of the photosensitive drum 1.

  In this embodiment, the developing device 4 is of a two-component developing system using a two-component developer (developer) in which mainly non-magnetic toner particles (toner) and magnetic carrier particles (carrier) are mixed. The developing device 4 includes a developing container that contains the developer, a developing sleeve that supports the developer and conveys the developer to a portion facing the photosensitive drum 1, and a developing sleeve that transfers the developer in the developing container. And a conveying screw as a developer conveying member that is conveyed to the outside. In this embodiment, the developing device 4 has the same charging polarity as that of the photosensitive drum 1 from the developer carried on the developing sleeve at the portion of the surface of the photosensitive drum 1 that has been subjected to the charging treatment, where the charge is attenuated by exposure. The toner charged to polarity is transferred.

  For example, when a full-color image is formed, the above-described charging, exposure, and development processes are performed in the first, second, third, and fourth image forming units Py, Pm, Pc, and Pb, respectively. The toner images of the respective colors formed on the surface of each photosensitive drum 1 in each image forming unit P are transferred to the outer peripheral surface (front surface) of the intermediate transfer belt 7 by the action of each primary transfer roller 8 in each primary transfer unit N1. Are sequentially superimposed and transferred (primary transfer). As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 7.

  The toner remaining on the surface of the photosensitive drum 1 after the primary transfer process (primary transfer residual toner) is removed and collected by the drum cleaner 5. Then, the photosensitive drum 1 is used for the next image formation.

  On the other hand, the recording material S is delivered from the feeding cassette 10 by the delivery roller 11 and conveyed to the registration roller 13 through the conveyance path 12A. Next, the recording material S is conveyed by the registration roller 13 to the secondary transfer portion N <b> 2 between the intermediate transfer belt 7 and the secondary transfer roller 14. The toner image on the surface of the intermediate transfer belt 7 is transferred to the recording material S in a process in which the recording material S is nipped and conveyed between the intermediate transfer belt 7 and the secondary transfer roller 14 in the secondary transfer nip portion N2. Transfer (secondary transfer).

  The toner (secondary transfer residual toner) remaining on the surface of the intermediate transfer belt 7 after the secondary transfer process is removed and collected by a belt cleaner 9 as an intermediate transfer member cleaning unit. Then, the intermediate transfer belt 7 is used for the next image formation.

  The recording material S to which the toner image has been transferred is conveyed to a heating and pressure fixing device 15 as a fixing unit. The fixing device 15 includes a heating roller 15A having a heat source, and a pressure roller 15B in pressure contact with the heating roller 15A. The recording material S carrying an unfixed toner image is introduced into a nip portion (contact region) formed by the heating roller 15A and the pressure roller 15B of the fixing device 15 with the image carrying surface facing upward. . The recording material S is heated and pressed by being sandwiched and conveyed by the heating roller 15A and the pressure roller 15B, and the toner image is fixed thereon.

  When an image is formed only on one side of the recording material S, the recording material S discharged from the fixing device 15 is guided to the discharge roller 17 by the switching flapper 16 and passes through the discharge roller 17 to the side surface of the apparatus main body 101. It is discharged onto the provided discharge tray 18.

  When images are formed on both sides of the recording material P, the recording material S discharged from the fixing device 15 is guided to the lower reverse conveyance path 12B by the switching flapper 16. In the reverse conveyance path 12B, the recording material S is switched back when the trailing edge reaches the reversal point Rp, and is sent to the double-side conveyance path 12C with the image carrying surface facing upward. Thereafter, the recording material S is sent out from the double-sided conveyance path 12C and conveyed to the registration roller 13 through the conveyance path 12A. Thereafter, the recording material S is conveyed to the secondary transfer portion N2 by the registration roller 13, and the toner image is transferred at the secondary transfer portion N2. Thereafter, the recording material S carrying an unfixed toner image is introduced into the fixing device 15 with the image carrying surface facing upward, where the toner image is fixed thereon. Thereafter, the recording material P discharged from the fixing device 15 is guided to the discharge roller 17 by the switching flapper 16 and is discharged onto the discharge tray 18 through the discharge roller 17.

2. Air Supply / Exhaust System Next, the air supply / exhaust system provided in the image forming apparatus 100 of this embodiment will be described.

  The image forming apparatus 100 includes a cooling device 102 that takes in outside air and lowers the outside air. Further, the image forming apparatus 100 includes an air supply unit 104 that supplies outside air that has passed through the cooling device and has been cooled to a lower temperature to the inside of the apparatus main body 101. In addition, the image forming apparatus 100 includes an exhaust unit 105 that exhausts air inside the apparatus main body 101 to the outside. The cooling device 102 and the air supply unit 104 are disposed above the image forming unit P in the gravity direction, and the exhaust unit 105 is substantially the same height as the image forming unit P in the gravity direction or from the image forming unit. Is also arranged below.

  As a result, the cool air supplied to the inside of the apparatus main body 101 spreads around the image forming unit P using gravity and is then discharged outside the apparatus main body 101. Even if 102 is used, the periphery of the image forming portion P can be efficiently cooled. This will be described in detail below.

  FIG. 2 shows the appearance of the front of the image forming apparatus 100 (corresponding to the front side of the paper in FIG. 1). FIG. 3 shows the appearance of the rear surface of the image forming apparatus 100 (corresponding to the back side of the paper in FIG. 1). Hereinafter, the front side of the image forming apparatus 100 is referred to as “front part” or “front part”, and the back side, which is the opposite side, is referred to as “rear part” or “rear part”.

  The image forming apparatus 100 includes a cooling device 102 disposed above the image forming units Py, Pm, Pc, and Pb in the direction of gravity. In this embodiment, the cooling device 102 is disposed at the rear upper right portion of the apparatus main body 101 when viewed from the front of the image forming apparatus 100. Further, the image forming apparatus 100 includes an air supply unit 104 disposed above the image forming units Py, Pm, Pc, and Pb in the direction of gravity. In the present exemplary embodiment, the air supply unit 104 is disposed in the upper right front portion of the apparatus main body 101 when viewed from the front of the image forming apparatus 100 and in the vicinity of the upper portion of the fourth image forming unit Pb. Further, a connecting duct 103 as a connecting means for connecting the cooling device 102 and the apparatus main body 101 is provided on the upper right side of the apparatus main body 101 when viewed from the front of the image forming apparatus 100. Further, an air supply port 109 is provided in the exterior portion of the apparatus main body 101 outside the air supply means 104, and the cooling duct 102 is connected to the air supply port 109 by connecting the connection duct 103 to the air supply port 109. 109. The air supply port 109 is also disposed above the image forming units Py, Pm, Pc, and Pb in the direction of gravity.

  The cool air is sent from the cooling device 102 through the connection duct 103 to the inside of the apparatus main body 101 by the air supply means 104 provided inside the connection portion between the connection duct 103 and the air supply port 109. The cool air sent to the inside of the apparatus main body 101 spreads around the photosensitive drum 1 and the developing device 4 through the gaps between the image forming portions Py, Pm, Pc, and Pb, as indicated by broken line arrows in FIG.

  On the other hand, the image forming apparatus 100 includes an exhaust unit 105 disposed in the gravity direction at substantially the same height as the image forming units Py, Pm, Pc, and Pb or below the image forming units Py, Pm, Pc, and Pb. Have In this embodiment, the exhaust unit 105 is a rear part of the apparatus main body 101 in the vicinity of the lower part of the first image forming unit Py on the opposite side of the air supply unit 104 with the image forming units Py, Pm, Pc, and Pb interposed therebetween. Is arranged. By this exhaust means 105, the air sent through the gaps between the image forming portions Py, Pm, Pc, and Pb is exhausted to the outside of the apparatus main body 101.

  As described above, in this embodiment, the air supply unit 104 is disposed farther from the fixing device 15 than the exhaust unit 105 inside the apparatus main body 101. More specifically, the air supply unit 104 is disposed at a position farthest from the fixing device 15 that is the largest heat source inside the apparatus main body 101, and the exhaust unit 105 is disposed in the vicinity of the fixing device 15. . In this embodiment, the fixing device 15 is disposed below each image forming unit P in the direction of gravity.

  In the present embodiment, the heat in the vicinity of the fixing device 15 is discharged to the outside of the apparatus main body 101, and the heat from the fixing apparatus 15 is more effectively discharged to the outside of the apparatus main body 101. Are provided separately. In this embodiment, the exhaust heat unit 106 is disposed at the rear portion of the apparatus main body 101 in the vicinity of the fixing device 15 rather than the exhaust unit 105.

  Note that, as in the present embodiment, the heat exhausting means 106 is substantially the same height as each image forming unit Py, Pm, Pc, Pb in the direction of gravity or below each image forming unit Py, Pm, Pc, Pb. When arranged, the exhaust heat means 106 can also function as an exhaust means similar to the exhaust means 105.

  With the air supply / exhaust system as described above, the airflow around each image forming unit P is directed from the fourth image forming unit Pb to the first image forming unit Py and from the front to the rear. As a result, the heat of the fixing device 15 is less likely to be transmitted to the periphery of each image forming portion P, and the airflow is efficient.

3. Configuration of Cooling Device, Air Supply Unit, Exhaust Unit, and Exhaust Heat Unit Next, the cooling device 102, the air supply unit 104, the exhaust unit 105, and the exhaust heat unit 106 will be further described.

  FIG. 4 shows a schematic configuration of an example of the cooling device 102. In this embodiment, the cooling device 102 using heat of vaporization is used as the cooling device 102. The cooling device 102 mainly includes a compressor (compressor) 121, a condenser (condenser) 122, a dryer 123, and an evaporator (evaporator) 124.

  The mechanism of the cooling device 102 will be described. First, the refrigerant is compressed by the compressor 121 and changed to a high-temperature and high-pressure refrigerant. When the refrigerant that has become high temperature and pressure is radiated in the condenser 122, the temperature of the refrigerant decreases and liquefies. The condenser 122 generates heat. The liquefied refrigerant is sent to the evaporator 124 after removing impurities such as moisture and dust in the dryer 123. In the evaporator 124, the refrigerant expands under reduced pressure. That is, the refrigerant evaporates in a low pressure and low temperature state, and at this time, the heat of vaporization is taken away from the surroundings. This portion is a portion that generates cold air. The outside air is cooled to a lower temperature when passing around the evaporator 124. This cold air is supplied to the inside of the apparatus main body 101 by the air supply means 104 through the connecting duct 103.

  In this embodiment, the capacity of the cooling device 102 is about 500 W and the compressor rating is about 150 W. As the refrigerant, R134a having a high operation efficiency among HFCs, which are alternative chlorofluorocarbons, was used.

In this embodiment, two 120 angle axial fans are used as the air supply means 104. The supply air volume of the air supply means 104 is about 1 to ³ m ³ / min. The air supply means 104 supplies outside air whose temperature has been lowered by about 5 to 10 ° C. by the cooling device 102.

In the present embodiment, one 120 angular axial fan is used as the exhaust means 105 and two 120 angular axial fans are used as the heat exhaust means 106. The exhaust means 105, exhaust air volume of heat discharging means 106 is about 0.5 to 1.5 m ³ / min, respectively, is about 1 to 3 m ³ / min.

  In this embodiment, since the cooling device 102 is disposed above the image forming portions P in the direction of gravity, the cool air efficiently and smoothly flows around the image forming portions P inside the apparatus main body 101 using the gravity. Sent to. Further, since the air supply means 104 is located farthest from the fixing device 15 inside the apparatus main body 101 and the exhaust means 105 is in the vicinity of the fixing device 15, the heat of the fixing device 15 is transferred to the periphery of each image forming portion P. The temperature rise around each image forming portion P can be efficiently prevented without telling the user.

4). Wastewater Treatment Device Next, treatment of water generated from the cooling device 102 will be described.

  As illustrated in FIG. 3, the image forming apparatus 100 includes a wastewater treatment device 108 that treats water discharged from the cooling device 102 and is disposed at the rear of the apparatus main body 101 behind the fixing device 15.

  Referring to FIG. 4, when the outside air passes around the evaporator 124 inside the cooling device 102, the outside air is cooled, and moisture contained therein is condensed on the surface of the evaporator 124. The condensed moisture falls onto the drain pan 125 disposed at the lower part of the evaporator 124 and is sent to the evaporation pan 126. An evaporating sheet 127 is provided on the evaporating dish 126. A part of the water drained to the evaporating dish 126 is evaporated by applying warm air to the evaporating sheet 127 by a fan (not shown) using heat generated from the condenser 122 or the compressor 121. Be made. The water that could not be evaporated here passes through the drain pipe 107 and is sent to the waste water treatment device 108.

  FIG. 5 shows a schematic configuration of the waste water treatment apparatus 108. In the waste water treatment apparatus 108, felt-like water absorbing members 181 bent in an L shape and absorbing water are arranged in two upper and lower stages. The water sent from the cooling device 102 through the drain pipe 107 passes through the opening 182 provided at the connecting portion between the drain pipe 107 and the waste water treatment device 108, and the L-shaped short portion 181A at the top of the water absorbing member 181. Fall into. This water moves in the water absorbing member 181 by capillary action, and slowly falls on the L-shaped long portion 181B extending vertically in the gravity direction. The water that has passed through the upper water absorbing member 181 can move further downward in the direction of gravity through the lower water absorbing member 181 disposed in contact therewith.

  The waste water treatment device 108 is installed outside the heat exhaust means 106 of the fixing device 15. Then, the air exhausted from the inside of the apparatus main body 101 by the exhaust heat means 106 is blown to the water absorbing member 181 through the opening 184 provided in the connection portion between the exhaust heat means 106 and the waste water treatment apparatus 108. This air is warmed by heat from the fixing device 15. By blowing high-temperature fixing exhaust heat onto the water absorption member 181 in this way, the water in the water absorption member 181 evaporates and is discharged to the outside of the waste water treatment device 108 by the exhaust fan 183 provided inside the waste water treatment device 108. The

  In this embodiment, a heat exhausting means 106 for the fixing device 15 is provided separately from the exhaust means 105, and the waste water treatment device 108 is supplied by air exhausted from the inside of the apparatus main body 101 by the heat exhausting means 106. Then, the waste water from the cooling device 102 is evaporated. As a result, the exhaust heat from the fixing device 15 can be effectively used to evaporate the waste water from the cooling device 102 while maintaining a smooth flow of air for cooling the image forming portion P. However, if desired, the exhaust means 105 and the exhaust heat means 106 can be used to evaporate the waste water from the cooling device 102 by the air exhausted from the inside of the apparatus main body 101 by the exhaust means 105 without providing the exhaust means 105 and the exhaust heat means 106 separately. May be.

  Conventionally, when a cooling device is installed in an image forming apparatus, it has been necessary to perform drainage work at a relatively high cost, or to install a drainage tank and replace it frequently. On the other hand, in the present embodiment, by providing the waste water treatment device 108 in the image forming apparatus 100 itself, the drainage work and the installation of the drain tank can be made unnecessary. Further, since the waste water treatment device 108 of this embodiment uses the waste heat of the fixing device 15, it is also useful for heat recycling.

  As described above, according to the present embodiment, the cooling device 102 is disposed above the image forming unit P in the gravity direction, so that the entire image forming unit P can be used even with the small cooling device 102 (that is, the small compressor). Can be cooled efficiently. This also stabilizes the temperature of the atmosphere in the image forming unit, so that the deterioration of the developer is difficult to proceed, and a stable image can be formed over a long period of time. Further, by disposing the cooling device 102 at a relatively high position in the image forming apparatus 100 that is above the image forming portion P in the direction of gravity, the waste water from the cooling device 102 is discharged smoothly using the gravity. Can lead to.

Example 2
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, the same or corresponding elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, temperature detecting means 20y, 20m, 20c, and 20b for detecting the temperature of the developer are installed in each of the developing devices 4y, 4m, 4c, and 4b (FIG. 7). And the control part 19 controls ON / OFF (operation | movement or a stop state) of the cooling device 102 based on the detection result of this temperature detection means 20y, 20m, 20c, 20b.

  That is, a heater (not shown) is installed inside the photosensitive drum 1 in order to maintain the surface temperature of the photosensitive drum 1 at a predetermined temperature. This is because if the temperature of the surface of the photosensitive drum 1 is low, moisture is condensed on the surface to cause image defects such as image flow. In this embodiment, the temperature of the surface of the photosensitive drum 1 is controlled to be between about 35 and 40 ° C. by the heater.

  On the other hand, the developer housed in the developing device 4 is not preferably changed greatly by temperature in order to stabilize the characteristics, and is preferably not high temperature in consideration of deterioration of the developer itself. In particular, when the temperature of the developer exceeds 40 ° C., the deterioration rate of the developer tends to rapidly increase. On the other hand, when the developer temperature exceeds 45 ° C., the fluidity of the developer deteriorates, and developer conveyance such as clogging in the conveyance path may occur. Although this temperature varies depending on the type of developer, in recent years, low-temperature fixing is becoming the mainstream for energy saving and the like. From such a situation, the developer is preferably controlled to be between about 30 to 40 ° C.

  FIG. 6 is a flowchart of control in the present embodiment. FIG. 7 shows a schematic control block in this embodiment.

  First, when the image forming apparatus 100 is turned on, the control unit 19 detects the temperature Ty of the developer in each of the developing devices 4y, 4m, 4c, and 4b indicated by the detection results of the temperature detecting units 20y, 20m, 20c, and 20b. , Tm, Tc, Tb information is read (step 1). The controller 19 turns on the cooling device 102 when any of the developer temperatures Ty, Tm, Tc, and Tb in the developing devices 4y, 4m, 4c, and 4b exceeds 35 ° C. (Step 2). 3). Then, the control unit 19 turns off the cooling device 102 when all of the developer temperatures Ty, Tm, Tc, and Tb in the developing devices 4y, 4m, 4c, and 4b are 35 ° C. or lower ( Steps 2, 4).

  Normally, during standby, in which the image forming apparatus 100 waits for an image formation start instruction after the power is turned on, the cooling device 102 remains off and only the air supply unit 104 is operated, and the device is left as it is without cooling the outside air. It is supplied to the inside of the main body 101. Except immediately after the end of the image forming operation, the ambient temperature of the image forming portion P including the developing device 4 can be set within a predetermined temperature range (the developing device 4 is approximately 30 to 30) by simply supplying outside air without cooling during standby. 40 ° C. and the photosensitive drum 1 can be maintained at about 35 to 40 ° C.).

  Here, in the present embodiment, as described above, ON / OFF switching of the cooling device 102 is controlled depending on whether the temperature of the developer is 35 ° C. or less. This is in consideration of the self-heating of the developing device 4. That is, it is known that when the developing device 4 is operated, the developer self-heats due to the rubbing between the developing sleeve or the conveying screw and the developer, and rises by about 3 to 5 ° C. from the ambient temperature. Therefore, if the cooling device 102 is operated after the developer temperature approaches 40 ° C., the cooling by the cooling device 102 may not be in time, and the developer temperature may exceed 40 ° C. It is. However, the above numerical values are merely examples, and do not limit the present invention.

  As described above, the temperature of the developer can be maintained within a preferable range (for example, 30 to 40 ° C.) while saving energy by the control of this embodiment. Therefore, according to the present embodiment, while saving energy, the color (density) is stabilized over a long period of time, image defects such as fogging images and streak images can be prevented, and the life of the developer can be extended. it can.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 15 Fixing apparatus 100 Image forming apparatus 101 Apparatus main body 102 Cooling apparatus 104 Air supply means 105 Exhaust means 106 Heat exhaust means 108 Waste water treatment apparatus P Image forming part S Recording material

Claims (6)

In an image forming apparatus having an image forming unit for forming a toner image by an electrophotographic method inside the apparatus main body,
A cooling device that takes in outside air and cools the outside air at a lower temperature; an air supply means for supplying outside air that has passed through the cooling device and has cooled to the inside of the device body; and air inside the device body to the outside An exhaust means for discharging,
The cooling device and the air supply unit are disposed above the image forming unit in the direction of gravity, and the exhaust unit is substantially the same height as the image forming unit in the direction of gravity or below the image forming unit. An image forming apparatus, wherein   The apparatus main body has a fixing device for fixing the toner image on the surface of the recording material by heating the recording material on which the toner image formed by the image forming unit is transferred. The image forming apparatus according to claim 1, wherein the air supply unit is disposed farther from the fixing device than the exhaust unit.   The temperature detection means for detecting the temperature of the atmosphere of the image forming unit, and the control means for switching the operation state or the stop state of the cooling device based on the detection result of the temperature detection means. The image forming apparatus according to 1 or 2.   The image forming apparatus according to claim 3, wherein the temperature detecting unit is installed in a developing device provided in the image forming unit.   5. The image forming apparatus according to claim 1, further comprising a wastewater treatment device that evaporates water discharged from the cooling device using air discharged from the inside of the apparatus main body. .   The waste water treatment apparatus is configured to cool the cooling device with air heated by heat from the fixing device and exhausted from the inside of the apparatus main body by exhaust means or exhaust heat means provided separately from the exhaust means. The image forming apparatus according to claim 5, wherein water discharged from the apparatus is evaporated.

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