JP2005049793A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a transfer belt is heated and kept warm by simple constitution without disposing dedicated heating and heat insulating means, thereby transfer performance is maintained with low power consumption and a stable image free from irregularities in an image can be obtained. <P>SOLUTION: The image forming apparatus 10 includes a developing device for forming a toner image on a photoreceptor drum 11, a transfer belt 12 with a conductive elastic layer for transferring the toner image onto transfer paper, and fixing rollers (14, 15) for fixing the transferred toner image on the transfer paper. In the image forming apparatus 10, an air passage 16 is located between the transfer belt 12 and the fixing rollers (14, 15), and an axial fan 16 for sending hot air from the fixing roller side to the transfer belt 12 side, a temperature sensor 20 for sensing the temperature of the transfer belt 12, and a controller for controlling a drive motor of the axial fan according to the output of the temperature sensor are arranged within the air passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, or a printer.

  In an image forming apparatus, for example, an image carrier made of a photosensitive drum is rotated and uniformly charged by a charging device, and then image exposure is performed on the image carrier by an exposure unit to form an electrostatic latent image. The electrostatic latent image is developed with a two-component developer or a one-component developer by a developing means to form a toner image, and the toner image is transferred onto a transfer sheet fed from a paper feeding device by a transfer means and fixed by a fixing device. ing. In the double-side mode, after image formation is performed on the front surface of the transfer paper, image formation is similarly performed on the back surface of the transfer paper.

  The transfer unit includes a contact transfer unit using a transfer conveyance belt, a transfer roller, and the like, and a non-contact transfer unit using a charger or the like. The transfer roller used in the contact transfer means rotates at almost the same linear speed (peripheral speed) as the image carrier, and a transfer bias is applied from the high-voltage power supply for transfer to electrostatically attract the transfer paper from the paper feeder. And the toner image on the image carrier is transferred onto the transfer paper. The transfer conveyance belt and the transfer roller are made of conductive rubber or a foamed member.

Such a contact transfer method is characterized in that it does not need to be discharged, can set a transfer current low, and generates less ozone than the charger method. Further, for the reasons (1) and (2) below, the transfer roller and the transfer belt have some electric resistance.
(1) When small size paper (width direction) is passed, transfer current is prevented from leaking to a portion other than the transfer paper and loss of transfer performance.
(2) Ensure transferability (adsorbability) when passing through low-resistance paper (hydrous paper).

  However, this resistance value is highly dependent on the environment, and if the resistance setting value is set high, the applied voltage increases excessively in a low-temperature and low-humidity environment, leading to image distortion and insufficient high-voltage output voltage. In a high-humidity environment, concentration of the transfer electric field causes reverse transfer and transfer failure at a small size, and in addition to the transfer belt, suction and separation failures occur. For example, as shown in FIG. 8, the surface electrical resistance of the transfer belt is low in a high temperature and high humidity environment. That is, since a high current value (vertical axis) can be obtained with a low applied voltage (horizontal axis), the required voltage can be small. However, a high applied voltage is required at low temperature and low humidity.

  In particular, as a countermeasure against water-containing paper, Patent Document 1 proposes that the transfer paper is dehumidified using a dehumidifying heater. However, this is effective for water-containing paper, but does not follow the increase in belt / roller resistance in a low-temperature environment, so that the resistance setting value is limited and a dedicated heater must be used.

  In addition, the moisture content of the transfer paper varies depending on the environmental humidity, and in a high temperature and high humidity environment, the transfer paper absorbs moisture, thereby causing the transfer paper to be remarkably deteriorated in transferability, resulting in defective transfer. For this reason, a 50 to 100 W dehumidifying heater is mounted in the paper feed cassette for dehumidifying to cope with these problems.

  In recent years, an apparatus using a photosensitive member having an amorphous silicon photosensitive layer is increasing for the purpose of extending the life of the photosensitive member. However, amorphous silicon photoconductors tend to adsorb moisture in the air, and so-called image flow tends to occur when water adheres to the photoconductor. Therefore, for example, as described in Patent Document 2, it is necessary to provide a heating means (heater) of 50 to 100 W on a part of the photoconductor to heat the photoconductor itself to prevent moisture adhesion.

  Further, in the fixing device, the toner transferred to the transfer device is fixed by a fixing roller heated to 170 ° C. or more. However, since the temperature around the fixing device is always 60 ° C. or more, the blowing device Heat is being discharged out of the machine. Patent Document 3 discloses an electrophotographic apparatus that uses this waste heat to heat a photoconductor (photosensitive drum) having an amorphous silicon photoconductor layer on a conductive substrate. As such an electrophotographic apparatus, an exposure device that creates a latent image on the photoreceptor, a developing device that forms a toner image on the latent image, and a transfer unit that transfers the toner image to a recording medium (transfer paper). In an electrophotographic apparatus including a fixing unit for fixing the toner image transferred by the transfer unit, a cover covering the periphery of the fixing unit (fixing roller) and air in the cover heated by waste heat of the fixing unit are blown. And a blower that connects the cover to the vicinity of the photosensitive member. As a specific example of the blower, a cover that also serves as a blowing path from the fixing roller to the photosensitive drum is provided, a blower fan is disposed above the cover, air is sent toward the fixing roller, and the air heated by the fixing roller Is guided to the inner surface of the cover and sent to the photosensitive drum.

In the electrophotographic apparatus disclosed in Patent Document 3, a cover that also serves as a blower path is provided from the fixing unit to the vicinity of the photosensitive drum, and a blower fan is provided above the inside of the cover. Necessary.
Further, a transfer residual toner conveyance path for conveying a transfer residual toner cleaned from the photosensitive member to the outside of the cleaning apparatus above the sheet conveyance path on the downstream side of the transfer roller. Is provided. In the configuration of Patent Document 3, hot air hitting the photosensitive member is blown upward, the transfer residual toner transport path is warmed, and the transfer residual toner remaining inside the transport path is solidified to cause transfer residual. There is a possibility that a phenomenon in which the toner conveying member arranged in the toner conveying path becomes unmovable. Particularly in recent years, due to the demand for energy saving, there are many cases where a toner for melting at a low temperature that is easy to melt is used, and such a phenomenon is likely to occur. In recent years, image forming apparatuses such as large-sized and high-speed copying machines have been miniaturized, and the distance between the lower surface of the cleaning apparatus and the paper conveyance path is usually only a few centimeters or less (outside the photoreceptor). Since the diameter is 20 cm or less, and in many cases 10 cm or less), the above-described phenomenon may occur from this point.
Japanese Patent Laid-Open No. 9-311560 Japanese Patent Publication No. 5-68702 JP-A-10-228225

  The object of the present invention is to provide heat and heat to the transfer belt, transfer roller, and photosensitive drum with a simple configuration without providing a dedicated heat and heat retaining means on the transfer roller, transfer belt, or photosensitive drum, thereby reducing power consumption. It is an object of the present invention to provide an image forming apparatus that maintains the transfer performance, can obtain a stable image without image distortion, and does not require a large space around the fixing device.

The image forming apparatus of the present invention includes a developing unit that forms a toner image on an image carrier, a transfer unit that transfers the toner image onto a transfer sheet, and a fixing unit that fixes the toner image transferred by the transfer unit. An air passage for flowing air provided between the transfer unit and the fixing unit, and a blower unit for flowing air from the fixing unit side to the transfer unit side provided in the air path. Is further provided.
In the image forming apparatus according to the aspect of the invention, it is preferable that the air path is disposed below a sheet conveyance path including the transfer unit.

  In such an image forming apparatus, the transfer unit may be a contact transfer unit that contacts and transfers the image carrier (claim 3). Further, it is preferable that the transfer member of the contact transfer means is composed of a transfer roller having a conductive elastic layer. In addition, it is preferable that the transfer member of the contact transfer unit is composed of a transfer belt having a conductive elastic layer. Further, it is more preferable that a temperature detection means is provided in the vicinity of the contact transfer means, and a temperature control means for controlling the operating state of the blower means by the detection signal is provided. In addition, it is more preferable that the image carrier is made of a photoreceptor having an amorphous silicon surface layer in order to achieve the effects of the invention (claim 7).

According to the image forming apparatus of the present invention (Claim 1), the waste heat of the fixing unit such as the fixing roller can be used to heat and keep the transfer unit such as the transfer roller or the transfer belt. Since the image carrier can be heated, a dedicated heater provided on the image carrier is not required. Thereby, power consumption can be suppressed. Furthermore, since an increase in resistance value of the transfer means due to environmental fluctuations (particularly low temperature) can be suppressed, stable transfer performance without image distortion can be obtained. Further, since the air blowing means is provided in the air passage, it is not necessary to provide a cover around the fixing means, and a large space is not taken around the cover.
Further, when the air path is disposed below the sheet conveyance path including the transfer means (Claim 2), the cleaning device for removing the toner on the surface of the image carrier is unnecessarily warmed. Therefore, it is possible to prevent the phenomenon that the transfer residual toner remaining in the interior solidifies.

  In the case of an image forming apparatus in which the transfer means is a contact transfer means for transferring in contact with the image carrier (Claim 3), the transfer paper is heated by direct heat conduction while the contact transfer means is in contact with the transfer paper. Therefore, the transfer paper can be heated through transfer means such as a suspension roller and a transfer member. As a result, the resistance value of the transfer paper can be stabilized, and in particular, a decrease in the resistance value due to the moisture content of the transfer paper under high humidity can be suppressed. Furthermore, since the transfer paper can be preheated through a transfer member such as a suspension roller and a transfer member, downstream fixing performance can be assisted.

  When the transfer member of the contact transfer means is composed of a transfer roller having a conductive elastic layer (Claim 4) or a transfer belt having a conductive elastic layer (Claim 5), By heating and maintaining the contact transfer member, it is possible to keep the resistance value of these contact transfer members substantially constant even if the temperature and humidity change. Therefore, the transfer bias applied to these contact transfer members by the change in temperature and humidity Need not be changed, or the change width can be reduced. Further, the transfer paper can be brought into close contact with the image carrier with elasticity. As a result, the transfer of the toner image onto the transfer paper becomes more reliable. Further, since the transfer member has conductivity, a transfer bias can be applied from the transfer member to the image carrier as in the conventional case.

  An image forming apparatus provided with a temperature detection means in the vicinity of the contact transfer means, and having a temperature control means for controlling the operating state of the blower means based on the detection signal, makes the temperature of the contact transfer means constant. The above effect can be further improved.

  When the image carrier is made of a photoconductor having an amorphous silicon-based surface layer (Claim 7), the photoconductor is further heated via the contact transfer means, so that the temperature characteristic such that the resistance value changes depending on the environmental temperature. Can be eliminated, and stable charging performance can be obtained. Further, since the photosensitive member is heated via the contact transfer means, it is possible to prevent moisture from adhering to the surface of the photosensitive member and to suppress image flow due to condensation of the amorphous silicon photosensitive member in a high humidity environment. In addition, since the amorphous silicon photoconductor has a harder surface than the organic photoconductor and the wear amount of the photosensitive layer is small, the mechanical life can be extended.

  Next, embodiments of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a main part showing an embodiment of an image forming apparatus of the present invention, FIG. 2 is a schematic cross-sectional view of a main part of another embodiment of the image forming apparatus of the present invention, and FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a block diagram showing a control-related configuration of the image forming apparatus in FIG. 1, and FIG. FIG. 7 is a flowchart showing an embodiment of the operation when the rotation of the fan related to the image forming apparatus of the present invention is ON / OFF-controlled. FIG. 7 shows the operation when the rotation of the fan related to the image forming apparatus of the present invention is controlled at a low speed / high speed. It is a flowchart which shows embodiment.

  An image forming apparatus 10 shown in FIG. 1 includes a photosensitive drum 11 that carries a toner image, a transfer belt 12 that transfers a toner image by bringing a transfer paper into contact with the photosensitive drum, and an intermediate portion of the transfer belt 12. A transfer roller 13 for applying a transfer bias to the photosensitive drum 11 via the transfer belt, and a fixing device including a heating roller 14 and a pressure roller 15 disposed on the upstream side of the transfer belt. Further, in the image forming apparatus 10, an air path 16 is provided between the fixing roller (particularly the pressure roller 15) and the transfer belt 12 and below the sheet conveyance path including the transfer belt 12, and air is blown into the air path. A fan, particularly an axial fan 17 is arranged. The sheet conveyance path is composed of the transfer belt 12 and the transfer sheet receiving member 36.

  The photosensitive drum 11 functions as an image carrier. In this embodiment, the surface is provided with an amorphous silicon photosensitive layer 11a. The photosensitive drum 11 is driven to rotate in the arrow R1 direction by a motor and a reduction gear (not shown). The transfer belt 12 is suspended by two suspension rollers 18 and 19. Then, by driving the suspension roller on the downstream side (left side in FIG. 1) with a motor, the upper side (conveying side) moves to the left side in FIG. 1, that is, the lower side (return side) moves to the right side. It is circulated to do. The suspension roller is driven by a gear or a belt by the same drive source as that of the photosensitive drum 11 and is tuned so that the linear velocity of both is the same. As the transfer belt 12, for example, a urethane rubber base material provided with a surface coat made of a conductive elastic material such as fluoro rubber is used.

  The transfer roller 13 is provided slightly downstream of the nip portion between the photosensitive drum 11 and the transfer belt 12, and is in contact with the photosensitive drum 11 from below the upper side of the transfer belt 12. For example, a current of about −50 μA is applied to the transfer roller 13 when the sheet is transferred. The applied bias is constant current controlled.

  A temperature sensor 20 that detects the temperature of the transfer belt 12 is provided outside the suspension roller 19 on the downstream side. As the temperature sensor 20, a contact thermistor, an infrared sensor or the like is used. If a contact thermistor is used, unnecessary wear on the surface of the transfer belt can be prevented by contacting the transfer belt 12 only when heating is required. The output of the temperature sensor 20 is feedback-controlled to the drive current of the motor that drives the axial fan 17 as will be described later. As target temperature, it is about 35-50 degreeC, for example, and around 42 degreeC is especially preferable. That is, when the temperature sensor is lower than the target temperature, the drive motor of the axial fan 17 is turned on or rotated at high speed, and ON / OFF control or high speed / low speed control is performed to turn the motor off or slow when the target temperature is exceeded. .

  The fixing roller includes a heating roller 14 disposed above and a pressure roller 15 provided so as to be in contact with the heating roller 14 below. As the heating roller 14, a metal roller having a heater 21 for fixing the toner onto the transfer paper and having a coating layer 14 a made of a fluororesin on the surface is used. As the heater 21, a halogen heater or the like is used. The pressure roller 15 is for applying a predetermined pressure to the transfer paper to ensure the contact pressure between the heating roller 14 and the transfer paper. For example, a metal shaft 15a and urethane rubber provided on the surface thereof are used. The rubber layer 15b. Of the heating roller 14 and the pressure roller 15, the pressure roller 15 is normally driven to rotate in the direction of arrow R3. As a result, the heating roller 14 rotates in the direction of arrow R4. The pressure roller 15 can be disposed on the upper side, and the heating roller 14 can be disposed on the lower side.

  The air passage 16 is a pipe having a rectangular cross section made of a metal plate or a plate made of synthetic resin, and is disposed below the transfer belt 12. The cross-sectional shape of the conduit is not limited to a rectangular shape, but is preferably a relatively flat rectangular shape in consideration of the width of the transfer paper and the space below the transfer belt 12. In this embodiment, one end (the left end in FIG. 1) of the air passage 16 is inclined so as to rise somewhat toward the pressure roller 15, and opens at a position close to the pressure roller 15. The other end (the right end in FIG. 1) rises upward and opens toward the lower surface of the transfer belt 12 on the return side. The axial fan 17 is disposed in the central portion of the air passage 16.

  In addition, it can replace with the axial flow fan 17, and can also employ | adopt other ventilation fans, such as a sirocco fan. Since the axial fan 17 is usually approximately the same height and width, as shown in FIG. 4, the planar shape of the air passage 16 is in the vicinity of the pressure roller 15 and in the opening portion (right opening portion) to be ejected. The intermediate portions 16 a and 16 b are tapered so that the width is the same as that of the transfer belt 12 and the width becomes narrow in the vicinity of the axial fan 17. Thereby, the suction action and the air blowing action of the axial fan 17 can be fully utilized. As shown in FIG. 4, it is preferable to provide an outlet 23 that opens on the side surface of the copying machine 22 near the outlet of the air passage 16. As a result, even if the amount of air blown from the axial fan 17 is increased, the amount of air flowing out to the photosensitive drum 11 side can be within an appropriate range.

  Since the image forming apparatus 10 configured as described above controls the transfer belt 12 at a constant temperature, it is not necessary to consider the temperature dependence of the electric resistance (belt resistance) of the transfer belt, and immediately after the power is turned on. Even when the image is transferred and after continuous image formation, the transfer property is not substantially changed. Further, since the transfer paper is warmed (preheated) by the transfer belt 12, the toner on the transfer paper is slightly melted, and a binding force is generated between the transfer paper and the transfer paper. Therefore, toner scattering that tends to occur when the transfer paper is separated from the transfer belt 12 can be prevented. This effect is a great advantage especially in the one-component jumping development system in which the electrostatic binding force between the transfer paper and the toner is weak.

  Further, by controlling the temperature of the transfer belt 12 to be constant, there is an advantage that stable image formation can be performed even in a low temperature environment. Further, since the transfer paper is kept warm through the transfer belt 12 in a high humidity environment, it is possible to prevent the transfer paper from absorbing moisture and lowering the transferability. In addition, in an amorphous silicon photoconductor, generally, surface charges cannot be held due to moisture adhering to the surface, resulting in an image flow phenomenon. In this image forming apparatus 10, a transfer belt 12 in contact with the photoconductive drum 11 is used. By heating the photosensitive member, moisture adhering to the photosensitive member can be removed, so that a stable image can be obtained.

  An image forming apparatus 24 shown in FIG. 2 includes a large transfer roller 25 and transfer paper receivers 26 and 37 disposed on the downstream side of the transfer belt 12 of the image forming apparatus 10 of FIG. In other configurations such as the air path 16 and the blower fan 17, the object whose temperature is to be controlled is the transfer roller 25 instead of the transfer belt, and thus the sheet conveyance path is configured by the transfer roller 25 and the transfer paper receivers 26 and 37. The image forming apparatus 10 is substantially the same as the image forming apparatus 10 in FIG. The temperature sensor 20 is arranged to detect the surface temperature of the transfer roller 25. Since the temperature of the transfer roller 25 is controlled in the image forming apparatus 24, the temperature of the transfer paper and the temperature of the photosensitive drum 11 can be controlled to be substantially constant as in the case of the apparatus of FIG. Therefore, it is possible to achieve substantially the same effect as the above-described case.

  FIG. 3 shows a case where the image forming apparatus 10 provided with the transfer belt 12 of FIG. In the copying machine 22, a paper feed tray 27 is provided below the image forming apparatus 10. This limits the space available on the photosensitive drum 11. However, if the flat air passage 16 is employed as described above, the installation space does not protrude from the paper feed tray 27 side. Further, although the cleaning device 28 is disposed on the downstream side of the photosensitive drum 11, the air path 16 is disposed below the transfer belt 12, so that interference with the cleaning device 28 in addition to the heating roller 14 is avoided. be able to. In addition, the cleaning device 28 is unnecessarily warmed, and the transfer residual toner remaining therein does not solidify. 3 is a paper feed path for supplying the transfer paper 30 from the paper feed tray 27 to the gap (paper feed port) between the photosensitive drum 11 and the transfer belt 12, and reference numeral 31 is the toner to the photosensitive drum 11. Reference numeral 32 denotes a main charger, and reference numeral 33 denotes an optical device that exposes a photosensitive drum based on an image to be copied to form an electrostatic image. Normally, a heater for reducing the humidity of the transfer paper is provided around the paper feed tray 27. However, when the hot air coming out of the air path 16 is guided to the paper feed tray 27 via the paper feed path 29, The power consumption of the heater can be reduced, and in some cases, the heater can be omitted.

  Next, a temperature control method for the transfer belt 12 and the transfer roller 25 will be described with reference to FIGS. Since the temperature control of the transfer belt 12 and the temperature control of the transfer roller 25 are substantially the same, the transfer belt will be described below as a representative. As shown in FIG. 5, a temperature sensor 20 that detects the temperature of the transfer belt 12 is connected to convert analog data into digital data and send the data to a motor controller 34 that controls the drive motor of the axial fan. Has been. The motor control unit 34 is provided, for example, in the control unit 35 of the entire copying machine. In the motor control unit 34, for example, based on the flowchart of FIG. 6, the drive motor of the axial fan is ON / OFF controlled.

  In the flowchart of FIG. 6, the power is first turned on (first step S1), and then the output of the temperature sensor of the transfer belt is read (second step S2). Next, it is determined whether or not the power is turned off (third step S3). If the ON state is confirmed, it is determined whether the measured temperature is higher or lower than a target temperature, for example, 42 ° C. (fourth step S4). If it is lower, the axial fan drive motor is turned on (fifth step S5), and the process returns to the second step S2. If the detected temperature is higher than the target temperature, it is turned off (sixth step S6), and the process returns to the second step S. Note that “turning on” and “turning off” include not only switching between ON and OFF but also continuing the original state.

  If the power is turned off in the third step S3, the axial fan is immediately stopped without going through the fourth step for determining the temperature (seventh step S7). Is turned off (eighth step S8), and the control is terminated. Note that the determination of “whether the power is turned off” in the third step S3 can be a determination of “whether there is an instruction for the power saving mode”. In that case, instead of “power OFF” in the seventh step S7, “transition to power saving mode” is set.

  In the above-described embodiment, the axial fan is ON / OFF controlled, but low-speed / high-speed switching control may be used. FIG. 7 is a flowchart for performing such “low speed / high speed” control. In this control method, “high-speed rotation” is used instead of “ON” in the fifth step S5 of FIG. 6, and “low-speed rotation” is used instead of “OFF” in the sixth step S6. “High speed rotation” means a rotation speed at which the temperature of the transfer belt becomes higher than the target temperature, and “low speed rotation” means a rotation at which the temperature of the transfer belt becomes lower than the target temperature. Showing speed. These speeds are set to appropriate values in advance. In addition to the above ON / OFF or low speed / high speed switching control, the difference between the target temperature and the measured temperature is calculated, and proportional control for continuously changing the speed of the drive motor according to the difference. If necessary, differential control and integral control can be added.

Next, specific experimental data will be given to explain the effect of the image forming apparatus of the present invention. The image forming apparatus used in the experiment is of the type provided with the transfer belt 12 shown in FIG. 1, and was incorporated in the image forming apparatus for the copying machine 22 shown in FIG. The specific configuration of each part is as follows.
Transfer belt: Material (base material) Urethane rubber (thickness 0.6mm)
Surface resistance 10 ⁸ Ω
(Surface coating) Fluoro rubber (thickness 0.02mm)
Surface resistance 10 ¹¹ Ω
Transfer belt volume resistance 10 ¹¹ Ω · cm
Transfer roller: Aluminum outer diameter 12mm
Transfer bias: −50 μA
Constant current control Suspension roller: Drive aluminum 16mm outside diameter
Followed aluminum outer diameter 16mm
Axial fan: 80mm square x 15mm thickness
DC24V, 5W
Control target temperature: 42 ° C

In the image forming apparatus, the volume resistance of the transfer belt is 2.9 × 10 ^{10 to} 5.8 × 10 ¹¹ Ω even if the environmental temperature and humidity change in the range of 10 ° C./15% to 35 ° C./85%. -It was substantially constant with cm. This means that the voltage applied to the bias from the transfer belt to the photosensitive drum becomes substantially constant, and high-quality image formation is performed. Further, the temperature of the transfer paper on which the toner image is formed by the image forming apparatus described above is 26 to 38 ° C. and the water content is 4.8 to 6.4%, and the temperature and the water content are kept almost constant. I understood. Further, by not using a dedicated heat retaining heater, the power consumption decreases to 50 to 100 W, and even if the power consumption of 5 W of the axial fan is subtracted, it decreases by about 45 to 95 W.

1 is a schematic cross-sectional view of a main part showing an embodiment of an image forming apparatus of the present invention. It is a principal part schematic sectional drawing which shows other embodiment of the image forming apparatus of this invention. 1 is a cross-sectional view showing a case where an image forming apparatus of the present invention is applied to a copying machine. It is the IV-IV sectional view taken on the line of FIG. FIG. 2 is a block diagram illustrating a control-related configuration of the image forming apparatus in FIG. 1. 6 is a flowchart illustrating an embodiment of an operation when ON / OFF control of rotation of a fan related to the image forming apparatus of the present invention is performed. 6 is a flowchart showing an embodiment of an operation when the rotation of the fan related to the image forming apparatus of the present invention is controlled at low speed / high speed. It is a temperature characteristic diagram of voltage-current of a general transfer belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photosensitive drum 11a Amorphous silicon type photosensitive layer 12 Transfer belt 13 Transfer roller 14 Heating roller 14a Coat layer 15 Pressure roller 15a Shaft 15b Rubber layer 16 Air path 17 Axial fan 18, 19 Suspension roller 20 Temperature sensor 21 Heater 22 Copying machine 23 Exit 24 Image forming device 25 Transfer roller 26 Transfer paper receiver 27 Paper feed tray 28 Cleaning roller 29 Paper feed path 30 Transfer paper 31 Developing device 32 Main charger 33 Optical device 34 Motor control unit 35 Control unit

Claims (7)

An image forming apparatus comprising: a developing unit that forms a toner image on an image carrier; a transfer unit that transfers the toner image onto a transfer paper; and a fixing unit that fixes the toner image transferred by the transfer unit.
An image forming apparatus further comprising an air path for flowing air provided between the transfer means and the fixing means, and a blower means for flowing air from the fixing means side to the transfer means side provided in the air path. apparatus.   The image forming apparatus according to claim 1, wherein the air path is disposed below a sheet conveyance path including the transfer unit.   The image forming apparatus according to claim 1, wherein the transfer unit is a contact transfer unit that contacts and transfers the image carrier.   The image forming apparatus according to claim 3, wherein the transfer member of the contact transfer unit includes a transfer roller having a conductive elastic layer.   The image forming apparatus according to claim 3, wherein the transfer member of the contact transfer unit includes a transfer belt having a conductive elastic layer.   4. An image forming apparatus according to claim 3, further comprising a temperature detection unit provided in the vicinity of the contact transfer unit, and a temperature control unit for controlling an operating state of the blower unit based on a detection signal from the temperature detection unit.   The image forming apparatus according to claim 1, wherein the image carrier is formed of a photosensitive member having an amorphous silicon surface layer.

Images