JP4742267B2 - Image forming apparatus - Google Patents

Description

The present invention, electrophotography, electrostatic recording, it relates to an image forming equipment which is used for various electrostatic printing and the like.

2. Description of the Related Art Conventionally, various proposals have been made on techniques for improving the image quality and preventing the occurrence of problems such as paper jams by controlling the temperature of constituent members of an image forming apparatus.
For example, the first intermediate transfer member that transports the toner image formed on the photosensitive member to the transfer and fixing region, and the first intermediate member while circulatingly moving in contact with the first intermediate transfer member in the transfer and fixing region. A second intermediate transfer body that receives the transfer of the toner image on the transfer body and conveys the toner image to the upstream position of the transfer and fixing area, and a first intermediate transfer body at a downstream position of the transfer and fixing area; An image forming apparatus having a configuration including a cooling unit that cools the temperature of the second intermediate transfer member to a softening point temperature or less of the toner has been proposed (for example, see Patent Document 1 below). According to this image forming apparatus, the toner images on the first and second intermediate transfer bodies are uniformly transferred, and the image quality of the finally obtained image is improved.
However, since the image forming apparatus disclosed in Patent Document 1 has a configuration in which the first and second intermediate transfer bodies are cooled together, the cooling apparatus itself is inevitably considerably large. There is a problem that the overall configuration of the image forming apparatus is complicated and energy consumption is also increased.

  Further, a device for fixing a toner image on a sheet while passing a sheet (recording medium) between a heating roller (heating member) and a pressure roller (pressure member) of the heat fixing device. A cooling device that cools a cleaning roller (cleaning member) that removes toner adhering to the pressure roller, for example, a fixing device including a heat pipe has been proposed (for example, see Patent Document 2 below).

  Also, in order to reduce the space for installing the fixing device, reduce the number of parts, and reduce the cost, a heating roller incorporating a halogen lamp and a support roller disposed in the vicinity of the heating roller are provided. The fixing belt is stretched so that it can be driven around. The support roller is provided with a heat pipe, and a cooling fin is provided on one end of the axial direction of the heat pipe, thereby cooling the fixing belt. There has also been proposed a fixing device that can cool a portion that has passed through the fixing nip of the fixing belt with a heat pipe without providing a cooling fan (see, for example, Patent Document 3 below).

  The above-described image forming apparatuses having various conventionally known transfer and fixing units are all transferred and fixed in a heated state, and there is a heating element in the vicinity of the image forming unit that forms a toner image. is doing.

By the way, a member for forming a toner image, in particular, an image carrier (photoreceptor) is easily affected by an operating characteristic due to a change in environmental temperature.
When the environmental temperature is higher than the predetermined temperature, the performance of the photoconductor is deteriorated. For example, a phenomenon that the toner adheres to the photoconductor becomes difficult to be removed, that is, a problem such as filming occurs, which is a major cause of image quality degradation. .
For these reasons, in various members having contact portions that communicate with the photosensitive member, it has been considered effective to provide a cooling device for the member in order to suppress excessive heat propagation to the photosensitive member.

On the other hand, in an image forming apparatus having an intermediate transfer member that conveys a transfer image from a photosensitive member toward the transfer fixing member, heat is inevitably transmitted from the transfer fixing member to the intermediate transfer member. Therefore, there is also a problem that the temperature of the transfer fixing member is lowered due to heat being removed from the contact portion, thereby causing deterioration of transfer characteristics.
In order to cope with such deterioration of the transfer characteristics, it has been devised to provide a separate heating device to add heat energy in order to suppress the temperature drop of the transfer fixing member. Energy consumption will increase.
In particular, in the configuration in which the transfer fixing member is provided with a cooling means for suppressing heat propagation to the photoconductor, a predetermined temperature must be ensured at the time of transfer. From the viewpoint, there was a problem that the energy consumption was considerably increased.

JP 2000-25272 A JP 2004-271556 A JP 2005-181474 A

As described above, in the image forming apparatus, it can be said that the temperature environment of each constituent member is an important element for maintaining each characteristic in a good state.
However, reducing energy consumption by temperature control is also an important issue in view of the practicality of the image forming apparatus.
Therefore, in the present invention, temperature control is performed on both the intermediate transfer member and the transfer fixing member, the transfer function of the transfer fixing member is maintained well while avoiding adverse effects on the image forming portion, and overall energy saving is achieved. It was decided to provide an image forming apparatus that was also made easier.

  In the present invention, the image forming apparatus includes a transfer fixing member that transfers an image on the intermediate transfer member, a heating unit that heats the image on the transfer fixing member, and a pressure member that forms a nip with the transfer fixing member. An image forming apparatus having a fixing device that transfers and fixes an image on a recording medium passing through the intermediate transfer member, the intermediate transfer body including a first cooling unit, and the transfer fixing member including a second cooling unit. A cooling medium comprising a gas or a liquid is brought into contact with the first cooling means and the second cooling means in this order, and the first cooling means and the second cooling means are transferred to the cooling medium. An image forming apparatus having a cooling auxiliary means for urging the heat transfer is provided.

  As the intermediate transfer member and the transfer fixing member, any conventionally known forms such as a roller shape and a belt shape can be applied.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein at least the second cooling means of the first cooling means and the second cooling means is a heat pipe.
In this case, the cooling medium may flow through the inner pipe of the heat pipe, or may flow outside.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the cooling medium is a gas and the cooling auxiliary means is an air blowing means.
The gas is preferably air in consideration of safety and the environment, but other materials having higher heat capacity can also be applied.

  In the invention of claim 4, the first cooling means and the second cooling means are connected by a common flow path, and the cooling medium flows through this flow path. An image forming apparatus according to any one of Items 1 to 3 is provided.

  According to a fifth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to fourth aspects, wherein the cooling temperature by the first cooling means is lower than the cooling temperature by the second cooling means. provide.

  According to a sixth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to fifth aspects, wherein the first cooling means and the second cooling means are controlled in an operation mode. To do.

  According to a seventh aspect of the present invention, the control of the first cooling unit is performed by the contact / separation operation from the intermediate transfer member, and the control of the second cooling unit is performed by the contact / separation operation from the transfer fixing member. An image forming apparatus according to claim 6 is provided.

  In the invention according to claim 8, the control of the first cooling means and the second cooling means in the operation mode is performed by switching on / off of the cooling medium delivery operation. A forming apparatus is provided.

In a ninth aspect of the present invention, a path for contacting the cooling medium in the order of the first cooling means and the second cooling means, and a separate cooling medium from the outside are brought into contact with the first and second cooling means. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a path to be moved.
It is assumed that the path can be switched according to the temperature control environment and usage conditions.

  According to a tenth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to ninth aspects, wherein toner having a Wadel practical sphericity φ of 0.8 or more is used as a developer.

  According to the present invention, the first cooling unit is provided on the intermediate transfer member, and the second cooling unit is provided on the transfer fixing member, so that the heat transfer to the image forming unit is effectively suppressed and the transfer fixing is performed. A good image transfer function in the member could also be maintained.

  By applying a heat pipe as a cooling means, excellent cooling efficiency can be obtained at low cost, and temperature unevenness in the axial direction of the transfer fixing member and the intermediate transfer member can be avoided with high cooling efficiency. It was possible to effectively suppress the heat propagation to the body and thus the image forming part.

By using the cooling medium of the cooling means as gas and the cooling auxiliary means as air blowing means, it is possible to select a material with higher safety.
Furthermore, by arranging the first and second cooling means on a common flow path to perform intake / exhaust of the cooling medium, the cooling auxiliary means (air blower fan) can be shared, the device configuration can be simplified, And cost reduction.

  By setting the cooling temperature of the first cooling means provided on the intermediate transfer member to be lower than the cooling temperature of the second cooling means provided on the transfer fixing member, the cooling medium can be used efficiently, Energy saving was achieved.

  Start-up by unnecessary cooling by switching and controlling the first cooling means and the second cooling means in accordance with various operation stages such as so-called normal output mode and start-up mode. The time delay and power loss can be suppressed, and the energy saving of the entire image forming apparatus was achieved.

  Since the control of the first cooling unit is performed by the contact / separation operation from the intermediate transfer member and the control of the second cooling unit is performed by the contact / separation operation from the transfer fixing member, each member of the cooling unit It is possible to clearly distinguish the energy usage state when the temperature of the member is in contact with the temperature drop = energy consumption occurs (with power loss), and when there is no contact, the temperature of the member does not decrease = energy consumption suppression (without power loss). Thus, the management of the apparatus is facilitated, and the energy saving of the entire image forming apparatus is achieved.

  Control of the first cooling means and the second cooling means in the operation mode is performed by switching on / off the cooling medium delivery operation, so that there is cooling (temperature drop of the transfer fixing member) = energy Generation of consumption (with power loss), no cooling (no temperature drop of the transfer fixing member) = energy consumption suppression (no power loss), and clear separation of usage status, transfer for more efficient energy consumption The temperature of the fixing unit can be controlled, and energy saving of the entire image forming apparatus is achieved.

  A path for sequentially bringing the cooling medium into contact with the second cooling means from the first cooling means, and a path for bringing the cooling medium into contact with the first and second cooling means separately from this path. By providing it, it was possible to perform further efficient cooling and respond to the demand for rapid cooling. In addition, by separately providing a path for taking in the refrigerant, the apparatus operating time itself is shortened, power loss is reduced, and the amount of energy used can be sufficiently suppressed from a practical viewpoint.

  By using toner having a Wadel practical sphericity φ of 0.8 or more as a developer, transferability was improved and high image quality was achieved.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following examples.
The image forming apparatus of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a main part of a tandem type color copying machine as an example of the image forming apparatus of the present invention.
The image forming apparatus 100 includes an image forming unit 1A positioned at the center of the main body, a paper feeding unit 1B positioned below the image forming unit 1A, and an image reading unit (not shown) positioned above the image forming unit 1A. Z).

In the image forming unit 1A, an intermediate transfer belt as an intermediate transfer body 2 having a transfer surface extending in the horizontal direction in the drawing is disposed.
A configuration for forming an image having a color complementary to the color separation color is provided on the upper surface portion of the intermediate transfer member 2.
That is, photoconductors 3Y, 3M, 3C, and 3B as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the intermediate transfer member 2. Has been.
Each of the photoreceptors 3Y, 3M, 3C, and 3B is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the charging device 4Y that performs image forming processing in the rotation process, 4M, 4C, 4B, writing devices 5Y, 5M, 5C, 5B as optical writing means, developing devices 6Y, 6M, 6C, 6B, primary transfer devices 7Y, 7M, 7C, 7B, and cleaning devices 8Y, 8M, 8C and 8B are arranged.
Note that the alphabets attached to the respective symbols correspond to the colors of the toners as in the case of the photoreceptor 3.
Each developing device 6Y, 6M, 6C, 6B contains a respective color toner.

The intermediate transfer body 2 is wound around a driving roller 9 and a driven roller 10 and is configured to be movable in the direction of arrow X in the figure at a position facing the photoreceptors 3Y, 3M, 3C, and 3B. It has become.
A cleaning device 11 for cleaning the surface of the intermediate transfer belt 2 is provided at a position facing the driven roller 10. The driven roller 10 may be the driving side and the roller 9 may be the driven side.

The surface of the photoreceptor 3Y is uniformly charged by the charging device 4Y, and an electrostatic latent image is formed on the photoreceptor 3Y based on image information from a predetermined image reading unit.
The electrostatic latent image is visualized as a toner image by a developing device 6Y containing yellow toner, and the toner image is formed on the intermediate transfer body 2 by a primary transfer device 7Y to which a predetermined bias is applied. Primary transfer is performed.
In the other photoreceptors 3M, 3C, and 3B, image formation is performed in the same process corresponding to each color, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 2 and superimposed.
After the transfer, the toner remaining on the photoreceptors 3Y, 3M, 3C, and 3B is removed by the respective cleaning devices 8Y, 8M, 8C, and 8B.
Further, after the transfer, the potentials of the photoconductors 3Y, 3M, 3C, and 3B are initialized by a static elimination lamp (not shown) so as to be ready for the next image forming process.

The paper feed unit 1B includes a paper feed tray 16 for stacking and storing sheets as the recording medium P, and a paper feed roller 17 for separating and feeding the sheets in the paper feed tray 16 one by one from the top. A pair of transport rollers (not shown) for transporting the fed paper, and after the paper is temporarily stopped and the oblique displacement is corrected, the transfer fixing member (transfer fixing belt) 73 constituting the fixing device 12 is fixed. A registration roller pair 19 is provided that feeds toward the nip N at a timing when the leading edge of the image coincides with a predetermined position in the conveyance direction.
The driving roller 9 of the intermediate transfer member 2 and the fixing device 12 are provided at close positions.
The fixing device 12 is configured such that a transfer fixing member (transfer fixing belt) 73 travels in a direction indicated by an arrow Y in the figure across a fixing driving roller 72, a secondary transfer roller 74, and a traveling roller 75.
A pressure roller 14 is provided opposite to the fixing drive roller 72, and this pressure roller 14 is pressed by the pressure means 21 such as a spring to form a nip N with the fixing drive roller 72. Yes.

A toner image T (hereinafter also simply referred to as toner) that has been primarily transferred from the photoreceptors 3Y, 3M, 3C, and 3B onto the intermediate transfer belt 2 is applied to the drive roller 9 by a secondary bias applying unit (not shown). The image is secondarily transferred to the secondary transfer roller 74 by electrostatic force by an applied bias (including superposition of AC, pulse, etc.).
Also, an adhesive transfer method by heating toner that is not electrostatic force or a method of transferring using both electrostatic force and adhesive may be applied.

Between the intermediate transfer member 2 and the fixing device 12, a heat insulating plate 20 is provided as a heat shielding member or a heat transfer inhibiting member that suppresses heat radiation (heat transfer) from the fixing device 12 to the intermediate transfer member 2. ing.
The heat insulating plate 20 is formed in a shape having an opening so as to suppress heat radiation to the intermediate transfer body 2 as much as possible while preventing secondary transfer from the intermediate transfer body 2 to the fixing device 12. The heat insulating plate 20 may be provided on either the main body of the fixing device 12 or the main body of the image forming unit 1A.

In addition, as the heat transfer inhibiting member made of a plate or the like, a plate-like member having a metallic luster with a low emissivity is suitable, and particularly excellent when two metal sheets are arranged with a minute gap or a heat insulating material interposed therebetween. It was confirmed that the effect was obtained.
In addition, a thin plate containing a micro heat pipe structure used for CPU cooling of a conventionally known notebook computer is also suitable, and when this is used, heat transfer can be suppressed while keeping the heat transfer suppressing member at a low temperature, High efficiency is obtained.
By such a heat insulating plate 20, the temperature rise of the intermediate transfer body 2 is suppressed, and thermal deterioration on the intermediate transfer body side can be suppressed.

  On the surfaces of the transfer fixing member (transfer fixing belt) 73 and the pressure roller 14, an elastic layer having a thickness of about 0.05 to 0.5 mm and a fluorine-based resin material (PFA, PTFE, etc.) having a thickness of about 10 to 30 μm, respectively. ) Release layer is coated or formed by a tube.

In the vicinity of the transfer and fixing member 73, a heating means for heating the toner image on the surface layer thereof, for example, a halogen heater 15 is provided.
In order to measure the surface temperature of the transfer fixing member 73 and the pressure roller 14, it is assumed that a predetermined thermistor (not shown) is provided in the non-image area.
In addition, a temperature controller (not shown) for controlling on / off of the halogen heater 15 based on the surface temperature of the transfer fixing member 73 is provided. The transfer fixing member 73 and the pressure roller 14 are configured to be capable of independently controlling the temperature.

  Further, the release layer formed on the respective surfaces of the transfer fixing member and the pressure roller 14 is formed of a conductive fluorine resin material in which a conductive substance such as carbon is dispersed, and this is connected to the core metal. As a result, a transfer bias can be applied between the release layers, the voltage of the transfer bias can be lowered, and toner scattering during transfer can be suppressed.

In the image forming apparatus 100 of FIG. 1, a first cooling unit 81 is provided on the intermediate transfer member (intermediate transfer belt) 2, and a second cooling unit 82 is provided on the transfer fixing member (transfer fixing belt) 73. It has been.
The first and second cooling means 81 and 82 have a function of cooling the intermediate transfer body 2 and the transfer fixing member 73, respectively. A cooling medium made of a predetermined gas or liquid is used as the first cooling means 81 and 82. The cooling means 81 is sequentially brought into contact with the second cooling means 82, and further urges heat to move from each of the first cooling means 81 and the second cooling means 82 to the cooling medium. Cooling auxiliary means is provided.

As the first cooling means 81 and the second cooling means 82, heat pipes are suitable.
When the cooling medium is a gas, for example, air or other gas material having a large heat capacity can be applied, and a blowing means such as a fan can be applied as the cooling auxiliary means. On the other hand, when the cooling medium is a liquid, a predetermined sealed flow path is provided, and water or other liquid material having a large heat capacity is applied, and a flow feeding means such as a pump can be applied as the cooling auxiliary means.

The first cooling means 81 and the second cooling means 82 are preferably connected by a common flow path. By allowing the above-described cooling medium to flow through these common flow paths, the cooling function can be efficiently enhanced.
The cooling temperature by the first cooling means 81 is preferably selected to be lower than the cooling temperature by the second cooling means 82. Thereby, a cooling-refrigerant resource can be utilized efficiently and energy saving as the whole apparatus is achieved.

The image forming apparatus of the present invention is not limited to the configuration shown in FIG. 1, and a transfer fixing roller is applied as a transfer fixing member 13 for transferring an image on the intermediate transfer body 2, for example, as shown in FIG. A relative roller configuration may also be used.
In the image forming apparatus 200 of FIG. 2, the pressure roller 14 is disposed at a position opposite to the transfer fixing member (transfer fixing roller 13) on the side opposite to the arrangement side of the intermediate transfer belt 2. The transfer fixing roller 13 and the pressure roller 14 form a nip N.
Note that components that are the same as those in the image forming apparatus 100 of FIG.

  The transfer fixing member (transfer fixing roller) 13 of the image forming apparatus 200 of FIG. 2 is one functional component that combines the transfer fixing belt 73 and the fixing driving roller 72 shown in FIG. Further, the material of the transfer fixing roller 13 can be the same as that of the pressure roller 14.

  Next, a basic transfer and fixing operation of the transfer and fixing roller method in the image forming apparatus 200 shown in FIG. 2 will be described with reference to FIG. The image forming apparatus 100 in FIG. 1 basically has the same operation configuration.

In FIG. 3, the toner image on the intermediate transfer member 2 is transferred from the intermediate transfer member 2 to the transfer fixing roller 13 with the drive roller 9 and the transfer fixing roller 13 in contact with each other or with a minute gap. It is made like that.
More specifically, first, the toner image on the transfer and fixing roller 13 is heated to a semi-molten state by condensing and irradiating the radiant energy emitted from the halogen heater 15 onto the transfer and fixing roller 13 by the reflector 32. The surface temperature of the transfer and fixing roller 13 is controlled to a predetermined temperature by the halogen heater 15 provided in the reflector 32 from when the power is turned on until the copying process is started. Has been made.
The surface temperature of the transfer and fixing roller 13 is preferably set to 100 ° C. or lower and more preferably adjusted to about 80 ° C. or lower so that the intermediate transfer member 2 is not excessively loaded with temperature.

In this embodiment, no heating means is provided inside the pressure roller 14, but a configuration in which the heating means is provided may be employed. In this case, a predetermined heating means, for example, a halogen heater (not shown) is provided inside the pressure roller 14, and this is assumed that the power is turned off in the copying process. In the process, electric power is supplied only to the halogen heater 15 provided in the reflector 32.
In the copying process, immediately after the toner image passes through the copying area of the reflector 32 and the halogen heater 15, the temperature distribution in the toner layer is directed toward the halogen heater 15 rather than the side in contact with the transfer fixing roller 13. The side that is in contact with the recording medium P is higher.
The surface temperature in the normal area of the transfer and fixing roller 13 is about 80 ° C. as described above, whereas the area subjected to heat irradiation by the halogen heater 15 is sufficient for the recording medium P in the subsequent process. In order to obtain a temperature at which a sufficient fixing strength is obtained, the temperature is set so that the contact interface temperature between the toner image and the recording medium is about 110 to 120 ° C.
In addition, when toner particles having a significantly smaller heat capacity compared with the recording medium P come into contact with the recording medium P, the temperature rapidly decreases. Therefore, in order to complete the fixing process at the nip outlet in a good state, the nip inlet Therefore, it is necessary to raise the toner temperature relatively high. From this point of view, the temperature and power are controlled in advance so that the contact interface temperature between the toner image and the recording medium is about 110 to 120 ° C. at the nip exit.

The heat source for heating the toner layer is not limited to the halogen heater 15 described above, and an induction heating method using an induction coil 131 as shown in FIG. 4 can also be applied.
In this case, a heat generation layer 130 made of a metal layer such as Ag is provided in the surface layer portion of the transfer fixing roller 13, and the heat generation layer 130 is swirled by the action of the induction coil 131 provided in proximity to the transfer fixing roller 13. Generates current and promotes heat generation. As a result, the toner on the transfer and fixing roller 13 is heated to lower the viscosity, and good fixing to the recording medium P is achieved at the nip portion constituted by the transfer and fixing roller 13 and the pressure roller 14. .

  In the image forming apparatus according to the present invention, since the intermediate transfer member 2 is in contact with the transfer fixing member (transfer fixing belt or transfer fixing roller), particularly during the transfer fixing operation, heat is transmitted from the intermediate fixing member 2 and the transfer fixing member. In view of the possibility of adversely affecting the image portion and causing a reduction in image quality, the first cooling unit 81 and the second cooling unit 81 are respectively provided in the intermediate transfer body 2 and the transfer fixing unit (transfer fixing belt and transfer fixing roller). The cooling means 82 is provided. As a result, the cooling state and the toner heating state can be efficiently controlled in accordance with the operation state of the apparatus, high image quality can be realized, and energy saving of the entire apparatus can be achieved.

  Hereinafter, the image forming apparatus of the present invention will be described with reference to specific examples regarding the configuration and functions of the first and second cooling units 81 and 82.

[Example 1]
A heat pipe is applied as the first and second cooling means 81 and 82.
FIG. 5 is a schematic configuration diagram of a main part of an image forming apparatus using a belt-type transfer fixing member.
In this image forming apparatus, the temperature propagating to the intermediate transfer body 2 depends on the temperature downstream of the cleaning device 61 in contact with the transfer fixing belt 73. As a second cooling means 82).
The heat pipe has an excellent cooling function, can effectively avoid heat conduction to the intermediate transfer body 2, and is excellent in the temperature rise suppression effect of the image forming portion.
In this image forming apparatus, a transfer fixing belt 73 is stretched across a fixing drive roller 72, a stretching roller 75, and a secondary transfer roller 74.
A cleaning roller 61 is in contact with the downstream side of the nip N.
The 2nd cooling means (heat pipe) 82 shall have a metal pipe shape, as shown in FIG.
A plurality of heat radiating fins 77 are provided at the end of the metal pipe shaft 76, and the fan 78 is used to blow air therethrough, whereby heat is transferred from the transfer fixing belt 73 in contact with the metal pipe shaft 76. Is taken away and the temperature drops.
Depending on the use conditions and purpose, as shown in FIG. 7, the temperature may be lowered only by contacting the metal pipe shaft 76 without providing the heat dissipating fins 77 at the ends.

[Example 2]
FIG. 8 is a schematic configuration diagram of a main part of the image forming apparatus in this example.
It is assumed that the first and second cooling means 81 and 82 provided on the intermediate transfer member (intermediate transfer belt) 2 and the transfer fixing member (transfer fixing belt) 73 are heat pipes, respectively. It has the structure connected with the path | route (the dashed-dotted line in FIG. 8).
8 is a schematic front view, FIG. 9 is a plan view from above the flow path, and FIG. 10 is a plan view from the side.

  As shown in FIG. 9, a heat pipe roller and a heat radiating fin 90 are provided as the first cooling means 81 that contacts the intermediate transfer body (intermediate transfer belt) 2, and the first cooling means 81 that contacts the transfer fixing member 73, that is, the transfer fixing belt. Similarly, as the second cooling means 82, a heat pipe roller and a heat radiating fin 77 are provided.

The first cooling means 81 and the second cooling means 82 are provided on a common flow path by a duct 91.
At both ends of the duct 91, fans 83 and 84 for intake and exhaust of a cooling medium, in this example, air, are attached to an intake port 86 and an exhaust port 87 provided in the apparatus main body cover 85, respectively.
The air having the outside air temperature (cooling medium) is taken into the duct from the intake fan 83, reaches the first cooling means 81, and the air that has become a temperature slightly higher than the outside air temperature by passing therethrough is the second air. It reaches the cooling means 82 and is then discharged from the exhaust fan 84 to the outside of the apparatus.
The first cooling means 81 and the second cooling means 82 may be provided with a blower fan or a duct so that intake and exhaust are performed separately, but the two cooling means 81 and 82 are common. By adopting a configuration provided on the flow path, it is possible to reduce the space of the entire apparatus and to reduce the cost.

In the image forming apparatus in this example, the temperature of the transfer fixing member, that is, the transfer fixing belt 73 is usually higher than that of the intermediate transfer body 2. For this reason, in the contact state between the two, heat propagates from the transfer fixing belt 73 to the intermediate transfer member 2. Therefore, the temperature relationship of the second cooling unit 82> the first cooling unit 81 is established in the cooling units arranged so as to be in contact with each other.
Considering this, if the cooling medium is moved from the cooling means having a lower temperature to the higher temperature, the cooling medium can be effectively used.
The temperature is appropriately set according to various production conditions, and specific examples are given below.
For example, it is assumed that the temperature in the vicinity of the second cooling unit (heat pipe roller) 82 on the transfer fixing belt 73 is about 65 ° C. after 15 minutes have passed since the image forming apparatus of this embodiment has been continuously operated.
Assuming that the outside air temperature is 23 ° C., air as a cooling medium is taken into the duct.
After the air passes through the heat dissipating fins 90 of the first cooling means (heat pipe roller) 81, the temperature becomes about 25 ° C. and rises by about 2 ° C.
This air is sent to the other second cooling means (heat pipe roller) 82 and used as a cooling medium. In this case, it is compared with a case where outside air is separately taken in and taken in from another flow path. Even so, it was confirmed that there was no practical difference in cooling efficiency.

Further, when the first cooling means 81 is arranged on the upstream side of the flow path of the cooling medium (air) and the second cooling means 82 is arranged on the downstream side of the flow path, the temperature is Since the rising air moves upward, it is advantageous to consider the direction of heat transfer.
By adopting such a configuration, for example, when the blower fan is stopped or the flow path is switched, the cooling medium (air) flows without causing stagnation, so that excellent cooling efficiency is maintained. The

Example 3
In the image forming apparatus in this example, the first and second cooling units 81 and 82 can be appropriately connected to and separated from the intermediate transfer member 2 and the transfer fixing belt 73, respectively.
If there is a member in contact with the transfer fixing belt 73 (the same applies to the intermediate transfer body 2), heat is taken away from the member and the temperature is lowered.
On the other hand, in order to maintain good transfer fixability, a predetermined temperature must be secured and maintained, and characteristics may be deteriorated only by unilateral cooling by a cooling means.
That is, if it is cooled by the cooling means, a device for raising the temperature is required separately from this, and the amount of energy consumption increases accordingly.

From such a current situation, the cooling means 81 and 82 are not in contact with each cooling object, particularly when the image is not being output, or when the machine is idle, such as when the machine is started up or when the process is adjusted. It is preferable to stop cooling as a state.
Therefore, for example, when the process adjustment is started, the cooling means 81 and 82 are separated from the intermediate transfer body 2 and the transfer fixing belt 73 by a predetermined contact / separation operation to be in a non-contact state, and when the normal image output operation is started. In order to perform cooling as necessary, contact is made.
In the case of such a configuration, it is necessary to accurately measure the temperatures of the intermediate transfer body 2 to be cooled and the area corresponding to the image forming area of the transfer fixing belt 73.
FIG. 11 is a temperature measurement state diagram showing the relative positional relationship between the object to be cooled (the intermediate transfer body 2 and the transfer fixing belt 73) and the image forming area. In FIG. 11, the temperature of the transfer fixing belt 73 is measured as a representative, and the positional relationship between the cleaning roller 61 and the traveling roller 75 is shown.
According to this, the temperature of the predetermined measurement region 300 of the object to be cooled (the intermediate transfer body 2 and the transfer fixing belt 73) is detected by the non-contact type temperature sensor, and the cooling means 81 is operated by the contact / separation operation until the temperature reaches a desired temperature. , 82 are held in a non-contact state. Then, when a normal image output operation is started, a contact state is set to perform cooling as necessary. As a result, the cooling unit can be operated effectively, the amount of energy consumption is suppressed, and energy saving of the entire image forming apparatus can be achieved.
It should be noted that the present invention is not limited to the non-contact type temperature sensor, and a contact type temperature sensor or a temperature measuring means that operates for a certain time depending on a certain operation mode may be used.

Example 4
In the apparatus configuration example shown in FIG. 8, the cooling means 82 is installed outside the transfer fixing belt 73. However, in this example, the cooling means 82 is provided inside the transfer fixing belt 73 on the opposite side. did. In this configuration as well, an excellent cooling effect was realized as in the configuration shown in FIG.
5 may be configured to function as a cooling unit, and the transfer roller 74 may be configured to function as a cooling unit.
By adopting such a configuration, an efficient temperature reduction effect can be obtained by controlling the winding angle of the roller when the transfer fixing belt 73 is stretched.
Further, by sharing the functional parts of the stretching roller 75 and the transfer roller 74, the cost of the parts can be reduced.
The cooling unit on the side of the intermediate transfer member (intermediate transfer belt) 2 can also have the same configuration.

Example 5
The image forming apparatus of the present invention controls the cooling state and the non-cooling state by switching on and off the air blown from the blower fans 83 and 84 in the cooling units 81 and 82 shown in FIGS. You may do it.
If there is a member in contact with the transfer fixing belt 73 (the same applies to the intermediate transfer member 2), heat is taken away from the member, and the temperature is lowered. On the other hand, in order to maintain a desired temperature for maintaining good transfer fixability, it is not necessary to unilaterally cool the cooling means. In such a case, a separate temperature control device is provided. This is necessary, and the power consumption increases accordingly.
In view of this, when the function of the cooling means is unnecessary, the air blowing by the fans 83 and 84 can be turned off.
As a specific operation, control is performed so that the blow is stopped when the process adjustment is started, and the blow is performed when the normal image output operation is started.
Further, as shown in FIG. 11, the temperature of the transfer fixing belt 73 is detected by a non-contact type temperature sensor, and similarly, the air is not blown until the temperature reaches a certain temperature. Thereby, the amount of energy consumption can be suppressed, and energy saving of the entire image forming apparatus can be achieved.
Moreover, you may make it control the air volume from each fan.

Example 6
In the image forming apparatus of the present invention, as shown in FIG. 9, the cooling medium is sequentially brought into contact with the second cooling means 82 from the first cooling means 81. A route for intake may be provided.
This will be described with reference to FIG.
In FIG. 12, normally, as in the example described in FIG. 9, external air is taken in from the intake port 86 by the intake fan 83 in the flow path of the duct 91, the first cooling means 81 is cooled, and then The second cooling means 82 is cooled and discharged from the exhaust port 87 to the outside of the main body by the exhaust fan 84.

By the way, when the image forming apparatus is in an operation mode or at a high speed, the temperature of the apparatus may be significantly increased.
In view of such a case, a route for taking in external air is provided separately from the common flow path (duct 91) so that efficient cooling is performed.
Specifically, in FIG. 12, the apparatus main body cover 85 is provided with an exhaust port 93 and an intake port 94, and in a normal state, the shutter 95 is in a duct that is not partitioned and communicates. Are partitioned in a predetermined flow path switching mode to change the air flow in the flow path (duct 91).
Similarly, the second flow path 102 and the third flow path 103 that are normally closed are opened together with the operation of the shutter 95, and the exhaust port 93 and the intake port 94 are opened. The air moves between them.
Air having an outside temperature is newly taken in from the intake port 94 and sent to the second cooling means 82 to cool it. As a result, air having a temperature lower than that of the air whose temperature has been increased by passing through the first cooling means 81 is sent, so that the temperature of the transfer fixing belt 73 on the second cooling means 82 side is effectively lowered. An effect is obtained.

  In the above configuration, the cooling control means may be combined depending on various conditions such as the image forming unit configuration, the main unit configuration, the machine speed, and the toner type.

  In the above description, the embodiment of the transfer-fixing belt system has been mainly described. However, the present invention can achieve the same effect even in the configuration of the transfer-fixing roller system.

Example 7
Next, examples of toner that can be applied to the image forming apparatus of the present invention will be described.
The transferability (transfer efficiency, fidelity) of toner from the intermediate transfer member to the transfer fixing member has an influence on the improvement in image quality, and the transferability of this toner is related to the shape of the toner.
In this example, the toner shape is optimized in order to achieve high image quality.
In particular, it was confirmed that excellent transferability can be obtained by applying a toner having a Wardel practical sphericity φ of 0.8 or more.
The sphericity φ is obtained by the following formula.
φ = (diameter of circle equal to particle projection area) / (diameter of circle circumscribing particle projection image)
Specifically, it can be easily calculated by taking an appropriate amount of toner on a slide glass, enlarging (500 times) with a microscope, and measuring 100 arbitrary toners.

1 is a schematic configuration diagram of an example of an image forming apparatus of the present invention. FIG. 3 is a schematic configuration diagram of another example of the image forming apparatus of the present invention. An explanatory view of an example when a transfer fixing member is a roller system is shown. An explanatory view of an example using another heat source when the transfer fixing member is of a roller type is shown. 1 is a schematic configuration diagram of a main part of an example of an image forming apparatus of the present invention. The schematic perspective view of the heat pipe of an example of a cooling means is shown. The schematic perspective view of another example of a cooling means is shown. 1 is a schematic plan view of a main part of an example of an image forming apparatus of the present invention. The top view of the state seen from the upper direction of the common flow path of a cooling means is shown. The top view of the state which looked at the common flow path which installed the cooling means from the side is shown. The schematic of the temperature measurement state of cooling object is shown. The top view of the other example of the flow path which installed the cooling means is shown.

Explanation of symbols

1A Image forming unit 1B Paper feeding unit 2 Intermediate transfer member (intermediate transfer belt)
3, 3Y, 3M, 3C, 3B Photoconductor 4Y, 4M, 4C, 4B Charging device 5Y, 5M, 5C, 5B Writing device 6Y, 6M, 6C, 6B Developing device 7Y, 7M, 7C, 7B Primary transfer device 8Y, 8M, 8C, 8B Cleaning device 9 Driving roller 10 Driven roller 11 Cleaning device 12 Fixing device 14 Pressure roller 15 Halogen heater 16 Paper feed tray 17 Paper feed roller 19 Registration roller pair 20 Heat insulation plate 21 Pressure means 32 Reflector 61 Cleaning roller 72 Fixing Driving Roller 73 Transfer Fixing Member 74 Secondary Transfer Roller 75 Traveling Roller 76 Metal Pipe Shaft 77 Heat Dissipation Fin 78 Fan 81 First Cooling Means 82 Second Cooling Means 83, 84 Fan 85 Device Body Cover 86 Inlet 87 Exhaust Port 90 Radiating fin 91 Duct 9 Measurements by the exhaust port 94 inlet 95 shutter 100 image forming apparatus 102 the second passage 103 third flow path 130 heating layer 131 induction coil 200 image forming apparatus 300 non-contact type temperature sensor region

Claims (10)

A transfer fixing member that transfers an image on the intermediate transfer member, a heating unit that heats the image on the transfer fixing member, and a pressure member that forms a nip with the transfer fixing member,
An image forming apparatus including a fixing device that transfers and fixes an image on a recording medium passing through the nip,
The intermediate transfer member includes a first cooling unit,
The transfer fixing member includes a second cooling unit,
A cooling medium made of a gas or a liquid is brought into contact with the first cooling means and the second cooling means in this order to transfer heat from the first cooling means and the second cooling means to the cooling medium. An image forming apparatus comprising a cooling assist means for prompting.   The image forming apparatus according to claim 1, wherein at least a second cooling unit of the first cooling unit and the second cooling unit is a heat pipe.   The image forming apparatus according to claim 1, wherein the cooling medium is a gas, and the cooling auxiliary unit is a blowing unit.   The first cooling means and the second cooling means are arranged in a common flow path, and the cooling medium flows through the common flow path. Item 4. The image forming apparatus according to any one of Items 1 to 3.   5. The image forming apparatus according to claim 1, wherein a cooling temperature by the first cooling unit is lower than a cooling temperature by the second cooling unit. 6.   The image forming apparatus according to claim 1, wherein the first cooling unit and the second cooling unit are controlled in an operation mode. The control of the first cooling means is performed by a contact / separation operation from the intermediate transfer member,
The image forming apparatus according to claim 6, wherein the second cooling unit is controlled by a contact / separation operation from the transfer fixing member.   7. The image forming apparatus according to claim 6, wherein the control of the first cooling unit and the second cooling unit in the operation mode is performed by switching on / off of the cooling medium delivery operation. .   There is a path for contacting the cooling medium in the order of the first cooling means and the second cooling means, and a path for contacting the cooling medium to the first and second cooling means separately from the path. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to any one of claims 1 to 9, wherein toner having a Wadel practical sphericity φ of 0.8 or more is used as a developer.

Images