JPH08248794A - Fixing device - Google Patents

Abstract

PURPOSE: To suppress high temp. accession of a pressure roll, and to prevent fixation wrinkles of a recording paper, by providing a cooling roll held in contact with a periphery of the pressure roll. CONSTITUTION: This fixing device is provided with the cooling roll 7, held in contact with the periphery of the pressure roll 4 for absorbing while discharging heat accumulation of the pressure roll 4, and an attaching/detaching means 8 for holding the cooling roll 7 in contact/uncontact with the pressure roller 4. As a result of composing the device in this way, a surface temp. of a fixing roll 1 is raised, while the halogen lamp heater 2 contained in the fixing roll 1 is heated, at the time of fixing the recording paper. The surface of the pressure roll 4 held in contact with and driven by the fixing roll 1 is heated by the heat conduction at this time, however the heat is conducted, while discharged to the cooling roll 7, since the cooling roll 7 is held in contact with the pressure roll 4, and as a result the temp. rising speed of the pressure roller 4 itself is reduced, possibly temp. drop occurs and the heating of the pressure roll 4 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a digital multi-functional peripheral, a laser printer, a facsimile and the like.

[0002]

2. Description of the Related Art FIG. 10 is a schematic view of a main part of a fixing device. The fixing roll 1 is supported by a pair of side plates (not shown), and has a halogen lamp heater 2 capable of heating therein. The pressure roll 2 is a cored bar 5 coated with an elastic layer and is provided so as to be in pressure contact with the fixing roll 1. Both ends of the pressure roll 2 are supported by side plates (not shown) so that they can be rotated together with the fixing roll 1. There is. The thermistor 3 is for detecting the fixable temperature of the fixing roll 1. The paper discharge sensor 24 monitors the paper passing state of the recording paper that has passed through the fixing device, and the paper discharge roller 25 discharges the fixed recording paper to a tray (not shown) outside the device. Arrow A indicates the rotation direction of the fixing roll 1. In such a configuration, the unfixed toner image transferred onto the recording paper P by the transfer device 6 is conveyed between the fixing roll 1 and the pressure roll 2 and is heated and pressed to be fused and fixed. .

[0003]

By the way, the recording paper conveyed between the fixing roll 1 and the pressure roll 2 and heat-fixed has a problem that fixing wrinkles generally occur. Therefore, as disclosed in Japanese Patent Laid-Open No. 52-160623, it has been considered that the meandering of the transfer material is changed to stabilize the conveyance by changing the angle of the fixing roller, thereby preventing wrinkles. However, a fixing wrinkle caused by the fixing temperature has not been solved. Here, focusing on the correlation between the surface temperature of the pressure roll and the fixing wrinkle, the relationship between the temperature rise of the pressure roll, which is in contact with the fixing roll containing the heat source for a long time, and the fixing wrinkle of the recording paper was examined. The data shown in FIG. 9 were obtained. According to this, as the temperature of the pressure roll rises, it was observed that fixing wrinkles were generated on the recording paper passed between the fixing roll and the pressure roll. This is because fixing wrinkles become remarkable as the temperature of the pressure roll rises. From this, the occurrence of fixing wrinkles has been a problem due to the phenomenon of high temperature of the pressure roll.

An object of the present invention is to provide a fixing device which suppresses the temperature rise of the pressure roll and prevents the fixing wrinkles of the recording paper.

[0005]

In order to achieve the above object, the fixing device of the invention according to claim 1 is characterized by comprising a cooling roll which is in contact with the peripheral surface of the pressure roll.

The fixing device of the invention according to claim 2 is characterized in that a plurality of cooling rolls are arranged along the circumferential surface of the pressure roll.

Further, in the fixing device of the invention according to claim 3, a cooling roll is provided in contact with the peripheral surface of the pressure roll, and the fixing roll, the pressure roll, and the cooling roll are respectively provided. It is characterized in that the rolls are arranged in contact with each other so that the axes of the rolls are aligned on a straight line.

Further, the fixing device of the invention according to claim 4 is provided with a cooling roll that abuts on the peripheral surface of the pressure roll, and a contacting / separating means that drives the cooling roll to come in contact with and separate from the pressure roll. Is characterized by.

Further, the fixing device of the invention according to claim 5 is characterized in that the cooling roll penetrates in the longitudinal direction and a plurality of hollow portions are formed along the circumference.

The fixing device of the invention according to claim 6 is characterized in that a notch reaching the peripheral surface of the cooling roll is formed in the hollow portion of the cooling roll.

Further, the fixing device of the invention according to claim 7 is characterized in that a spiral groove is formed along the longitudinal direction on the peripheral surface of the cooling roll.

Further, the fixing device of the invention according to claim 8 is such that the cooling roll is in contact with the peripheral surface of the pressure roll, the contacting / separating means for driving the cooling roll to contact with and separate from the pressure roll, and the pressure roll. Temperature detecting means provided on the peripheral surface of the pressure roll, and when the peripheral surface temperature of the pressure roll rises to a predetermined first set temperature, the cooling roll is brought into contact with the pressure roll. And a control unit for escaping the cooling roll from the pressure roll when the temperature falls to a second preset temperature.

According to a ninth aspect of the present invention, in a fixing device, a paper discharge sensor for detecting the conveyance of recording paper after fixing, a cooling roll in contact with the peripheral surface of a pressure roll, and a pressure applied to the cooling roll. A contact / separation unit that allows contact with and separation from the roll, a temperature detection unit provided on the peripheral surface of the pressure roll, and a discharge sensor when the peripheral surface temperature of the pressure roll reaches a predetermined first set temperature. After the detection of the first sheet of recording paper that has been detected or has passed, a control unit that presses the cooling roll against the pressure roll after the recording paper is ejected is provided.

[0014]

According to the structure of the first aspect, since the cooling roll that comes into contact with the pressure roll is provided, the temperature rise of the pressure roll surface temperature can be suppressed and lowered, and the high temperature region of the pressure roll can be suppressed. It is possible to prevent the wrinkle of the recording paper from being fixed at the time of fixing, which occurs in 1.

Further, according to the second aspect of the invention, since a plurality of cooling rolls that come into contact with the pressure rolls are provided along the rotation direction of the pressure rolls, the temperature of the pressure rolls can be rapidly lowered, and The temperature rise can be suppressed efficiently.

According to the third aspect of the present invention, the fixing roll, the pressure roll and the cooling roll are brought into contact with each other so that the axes of the rolls are aligned on a straight line. While suppressing the temperature rise and lowering the temperature, it becomes possible to press the pressure roll more toward the fixing roll,
The nip width between the fixing roll and the pressure roll can be increased, and the toner fixing property on the recording paper is also improved.

According to the structure described in claim 4, since the contacting / separating means for driving the cooling roll to contact with and separate from the pressure roll is provided, the cooling roll can be separated when it is not necessary. It is possible to prevent the pressure roll from being affected by the rotation load and temperature.

Further, according to the fifth aspect of the invention, since the hollow hole penetrating the cooling roll in the longitudinal direction is formed, the surface area of the cooling roll itself can be increased and the heat radiation effect can be improved. Therefore, the surface temperature of the pressure roll can be quickly lowered.

According to the sixth aspect of the invention, since the notch reaching the peripheral surface of the cooling roll is formed in the hollow hole formed in the cooling roll, the hollow hole is easily exposed to the outside air and easily passed therethrough. The heat dissipation effect of the roll itself can be improved.

Further, according to the structure of the seventh aspect, since the spiral groove is formed along the longitudinal direction of the cooling roll, the surface area of the cooling roll itself can be enlarged and the heat radiation effect can be improved. Moreover, since it is formed in a spiral shape, the outside airflow easily flows as the cooling roll rotates, and the cooling efficiency also improves.

According to the eighth aspect of the invention, the contacting / separating means for driving the cooling roll into and out of contact with the pressure roll is controlled according to the upper and lower limit temperature set values of the pressure roll. It is possible to quickly raise or lower the temperature according to the surface temperature of the pressure roll at that time. Therefore, it is possible to prevent the recording paper fixing wrinkle at the time of fixing which occurs in the high temperature region of the pressure roll.

According to the ninth aspect of the invention, when the cooling roll is brought into contact with the pressure roll, the recording paper is controlled so as not to be present in the fixing device. Disturbance or deterioration of the fixed image can be prevented.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same members as those in the conventional configuration shown in FIG. 10 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows the construction of the essential parts of a fixing device according to the first and fourth embodiments of the present invention. In the figure, the cooling roll 7 comes into contact with the peripheral surface of the pressure roll 4 to remove the heat stored in the pressure roll 4 and radiate the heat.
Is to bring the cooling roll 7 into contact with or separate from the pressure roll 4. The contacting / separating means 8 includes a contacting / separating lever 10 rotatably supported by a support shaft 9, and a solenoid 11 for operating the contacting / separating lever 10 so as to separate the cooling roll 7 from the pressure roll 4. And a sub ring 12 for urging the cooling roll 7 in a direction of contacting the pressure roll 4. A support hole 10a for supporting the cooling roll shaft 13 is formed on one end side of the contact / separation lever 10, and a fitting hole 10b for fitting with the connecting shaft 14 connected to the plunger 11a is formed on the other end. There is. Temperature detecting means 15
Is for detecting the surface temperature of the pressure roll 4. With this configuration, when fixing the recording paper, the heater 2 incorporated in the fixing roll 1 is heated, and the surface of the fixing roll 1 is heated. At this time, the pressure roll 4, which is in pressure contact with the fixing roll 1 and rotates following the fixing roll 1, also has its peripheral surface heated by heat transfer.
, The heat is transferred to the cooling roll 7 and is radiated, so that the temperature rising rate of the pressure roll 4 itself becomes slow or the temperature drops, and the pressure roll 4 is heated. Can be reduced. Therefore, it is possible to prevent the occurrence of fixing wrinkles due to the high temperature of the pressure roll 4.

FIG. 2 shows the essential structure of the fixing device according to the second embodiment of the present invention. In the figure, a plurality of cooling rolls 16 are provided so as to abut along the circumference of the peripheral surface of the pressure roll 4, and the cooling roll shaft 16 a is supported by a bearing hole 17 a of the roll support 17. The contacting / separating means 8a contacts or separates the cooling roll 16 from the pressing roll 4 and presses the contacting / separating lever 18 rotatably supported by the support shaft 9 and the contacting / separating lever 18. A solenoid 11 that operates to move the cooling roll 16 away from the roll 4 and a sub ring 12 that urges the cooling roll 16 in the direction in which the cooling roll 16 contacts the pressure roll 4 are provided. Further, one end of the contact / separation lever 18 is provided on the roll support 17
A support hole 18a for supporting a connecting shaft 19 connected to the is formed, and a fitting hole 18b for fitting the connecting shaft 14 connected to the plunger 11a is formed at the other end. In this way, by providing a plurality of cooling rolls 16 that are brought into contact with the pressure roll 4, it is possible to increase the heat transfer property and increase the surface area of heat radiation. Therefore, it is possible to efficiently suppress the temperature rise of the pressure roll 4 and lower it.

FIG. 3 shows the essential structure of a fixing device according to the third embodiment of the present invention. In the figure, the cooling roll 7, the pressure roll 4, and the fixing roll 1 are brought into contact with each other such that the axes of the rolls are aligned on a straight line between the contact of the rolls. The contacting / separating means 8b serves to bring the cooling roll 7 into contact with or separate from the pressure roll 4. The contacting / separating means 8b includes a contacting / separating lever 20 rotatably supported by a support shaft 9, and a solenoid 11 for operating the contacting / separating lever 20 in a direction to separate the cooling roll 7 from the pressure roll 4. And a sub ring 12 for urging the cooling roll 7 in a direction of contacting the pressure roll 4. A support hole 20a for supporting the cooling roll shaft 13 is formed at one end of the contact / separation lever 20, and the plunger 1 is provided at the other end.
A fitting hole 20b that fits with the connecting shaft 14 that is connected with 1a is formed. With this configuration, in addition to the operation of the first embodiment, the cooling roll 7 with respect to the pressure roll 4
The contact force of the pressure roller 4 increases the pressure contact force of the pressure roller 4 with respect to the fixing roller 1, the nip width H at the pressure contact position can be enlarged, the fixing time on the recording paper can be extended, and the toner fixability is improved.

FIG. 4 is a sectional view of a cooling roll according to the fifth embodiment of the present invention. In the figure, the cooling roll 21 is formed by forming a plurality of hollow portions 21b that penetrate in the longitudinal direction along the circumference. By forming the hollow portion 21b in the cooling roll 21 in this way, the surface area is increased and the heat dissipation efficiency is increased.

FIG. 5 is a sectional view of a cooling roll according to the sixth embodiment of the present invention. In the figure, the cooling roll 22 is formed with a plurality of hollow portions 22b penetrating in the longitudinal direction along the circumference, and the hollow portions 22b and the cooling roll 22 are formed.
The notch 22c is formed in the peripheral surface of the. By doing so, it is possible to easily let the outside air pass through the hollow portion 22b and improve the heat dissipation efficiency.

FIG. 6 is a side view of a cooling roll according to the seventh embodiment of the present invention. In the figure, the cooling roll 23 has a spiral groove 23b formed along the longitudinal direction. By doing so, the surface area of the cooling roll 23 is increased and the flow of the outside air is generated, so that the heat radiation efficiency can be improved.

FIG. 7 is a control block diagram of the fixing device according to the eighth and ninth embodiments of the present invention. In the figure, the first detection unit 30 changes the temperature detection signal of the thermistor 3 that detects the surface temperature of the fixing roll 1 from an analog signal to a digital signal, and the second detection unit 31 indicates the surface of the pressure roll 4. The temperature detection signal of the temperature detection means 15 for detecting the temperature is changed from an analog signal to a digital signal. The detection unit 32 detects the presence or absence of a signal from the paper discharge sensor 24 that detects the discharge of the recording paper after fixing. The contact / separation drive unit 33 energizes the solenoid 11 to move the cooling roll 7 to the pressure roll 4. It abuts or separates.
The main motor drive unit 34 energizes the drive motor 35 to perform drive control. In addition to driving the fixing roll 1 or the paper discharge roller 25, the main motor drive unit 34 also controls drive of an image recording system (not shown). The heater driving unit 36 energizes the halogen lamp heater 2 to heat the fixing roll 1.
The memory 37 stores predetermined control data of each drive unit. The control unit 38 is a microcomputer that controls each of the above units.

With the above construction, FIG. 8 shows the eighth and ninth aspects of the present invention.
It is what showed the cooling process of the pressure roll which concerns on an Example. The surface temperature of the pressure roll 4 pressed against the fixing roll 1 heated by the halogen lamp heater 2 is detected by the temperature detecting means 15 to determine whether or not it has reached the first set temperature (process 101), and the first set. When the temperature (setting value = 1) has not been reached (N in process 101), the temperature of the pressure roll is monitored, and when the temperature has reached the setting temperature (set value = 1) (Y in process 101), In the next process, it is determined whether the paper discharge sensor 24 located on the downstream side of the fixing device detects the recording paper in the middle of paper discharge (process 102).
When the paper ejection sensor 24 does not detect the recording paper in the middle of paper ejection (N in process 102), the paper ejection sensor 24 monitors the recording paper ejected. If the recording paper in the middle of discharging is detected (Y in process 102), it is determined whether the next recording paper discharge completion is detected (process 103). If the recording paper discharge completion is not detected, the paper discharge sensor 24 monitors the recording paper discharge completion (N in process 103). If the completion of recording paper discharge is detected (Y in process 103), the cooling roll 7 is brought into contact with the pressure roll 4 (process 104). After that, it is determined whether the surface temperature of the pressure roll 4 has dropped to the second set temperature (set value = 2) (process 105), and if not (N of process 105), the temperature detection means 15
At, the surface temperature of the pressure roll 4 is monitored. If it has descended (Y in process 105), the cooling roll 7 is separated from the pressure roll 4, the contact is released, and this process ends.
The above-mentioned first set temperature is, for example, 130 ° C., the second
The set temperature may be set to, for example, 100 ° C. In addition to silicone rubber, the material of the elastic layer covering the core metal 5 of the pressure roll 4 includes ethylene propylene diene molmer (EPDM), chloroprene rubber,
It may be chlorosulfonated polyethylene rubber, cross-linked polyethylene or the like.

[0032]

According to the invention of claim 1, by bringing the cooling roll into contact with the pressure roll, the temperature rise of the surface temperature of the pressure roll can be suppressed and lowered. It is possible to prevent a wrinkle on the recording paper fixing at the time of fixing which occurs in the high temperature range. Further, it is possible to prevent the occurrence of paper jam at the time of fixing.

According to the invention of claim 2, in addition to the effect of claim 1, the temperature of the pressure roll can be rapidly lowered.
Moreover, since the temperature rise can be suppressed efficiently, the cooling efficiency can be improved. Further, since the cooling roll can have a small diameter, the device can be downsized.

According to the invention of claim 3, in addition to the effect of claim 1, the nip width between the fixing roll and the pressure roll can be increased, and the fixing property of the toner on the recording paper is also improved.

Further, according to the invention of claim 4, the cooling roll is brought into contact with or separated from the pressure roll as occasion demands, so that the deformation of the peripheral surface of the pressure roll can be prevented and the durability can be improved. it can.

According to the fifth aspect of the invention, by forming the hollow hole penetrating the cooling roll in the longitudinal direction, the surface area of the cooling roll itself can be increased and the heat radiation effect can be improved. Further, the surface temperature of the pressure roll can be quickly lowered, and the cooling efficiency can be improved.

According to the invention of claim 6, the hollow hole formed in the cooling roll is provided with a notch reaching the peripheral surface of the cooling roll, so that the hollow hole is easily exposed to the outside air,
In addition, since it can be easily passed through, the heat radiation effect of the cooling roll itself can be improved.

According to the invention of claim 7, since the spiral groove is formed along the longitudinal direction of the cooling roll, the surface area of the cooling roll itself can be increased and the heat radiation effect can be improved. Further, as the cooling roll rotates, the external air flow around the spiral groove easily flows, and the cooling efficiency also improves.

Further, according to the invention of claim 8, the contacting / separating means is controlled in accordance with the temperature setting values of the upper and lower limits of the pressure roll, which corresponds to the surface temperature of the pressure roll at that time. Then, the temperature can be raised or lowered quickly. Therefore, it is possible to prevent the recording paper fixing wrinkle at the time of fixing which occurs in the high temperature region of the pressure roll.

According to the ninth aspect of the invention, when the cooling roll is brought into contact with the pressure roll, the recording paper is controlled so as not to exist in the fixing device, thereby preventing the fixed image from being disturbed or deteriorated. be able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram of main parts of a fixing device according to first and fourth embodiments of the present invention.

FIG. 2 is a configuration diagram of a main part of a fixing device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of a fixing device according to a third exemplary embodiment of the present invention.

FIG. 4 is a sectional view of a cooling roll according to a fifth exemplary embodiment of the present invention.

FIG. 5 is a sectional view of a cooling roll according to a sixth embodiment of the present invention.

FIG. 6 is a side view of a cooling roll according to a seventh exemplary embodiment of the present invention.

FIG. 7 is a control block diagram of a fixing device according to eighth and ninth embodiments of the present invention.

FIG. 8 is a flowchart of a cooling process according to eighth and ninth embodiments of the present invention.

FIG. 9 is a distribution diagram of fixing wrinkles in a fixing device of a conventional example.

FIG. 10 shows a main configuration of a conventional fixing device.

[Explanation of symbols]

 1 ... Fixing roll 2 ... Halogen lamp heater 3 ... Thermistor 4 ... Pressure roll 5 ... Core metal 6 ... Transfer device 7,16,21,22,23 ... Cooling roll 8 ... Contacting / separating means 9 ... Spindle 10,18 , 20 ... Contact / separation lever 11 ... Solenoid 12 ... Spring 13 ... Cooling roll shaft 14 ... Connection shaft 15 ... Temperature detecting means 17 ... Roll support 19 ... Connection shafts 21a, 22a, 23a ... Shafts 21b, 22b ... Hollow part 22c ... Cut portion 23b ... Groove 24 ... Paper ejection sensor 25 ... Paper ejection roller 30 ... First detection portion 31 ... Second detection portion 32 ... Detection portion 33 ... Contact / separation drive portion 34 ... Main motor drive portion 35 ... Drive motor 36 ... Heater Drive unit 37 ... Memory 38 ... Control unit

Claims (9)

[Claims] 1. A fixing roll having a heating means therein and a pressure roll in pressure contact with the fixing roll are provided, and the recording paper is nip-conveyed between the fixing roll and the pressure roll. A fixing device for fixing unfixed toner, comprising: a cooling roll in contact with a peripheral surface of the pressure roll. 2. The fixing device according to claim 1, wherein a plurality of the cooling rolls are arranged along a circumferential surface of the pressure roll. 3. A fixing roll having a heating means therein and a pressure roll which is brought into pressure contact with the fixing roll are provided, and the recording paper is sandwiched and conveyed between the fixing roll and the pressure roll, and the recording paper on the recording paper is conveyed. In a fixing device for fixing unfixed toner, a cooling roll is provided in contact with the peripheral surface of the pressure roll, the fixing roll, the pressure roll,
A fixing device, wherein the cooling roll and the cooling roll are arranged in contact with each other such that the axes of the rolls are aligned on a straight line. 4. A fixing roll having a heating means therein and a pressure roll which is in pressure contact with the fixing roll are provided, and the recording paper is nip-conveyed between the fixing roll and the pressure roll so that the recording paper is held on the recording paper. In a fixing device for fixing unfixed toner, a cooling roll that contacts the peripheral surface of the pressure roll,
A fixing device comprising: a contacting / separating unit that drives the cooling roll so as to freely contact and separate from the pressure roll. 5. The fixing device according to claim 1, wherein the cooling roll penetrates in a longitudinal direction and a plurality of hollow portions are formed along a circumference thereof. apparatus. 6. The fixing device according to claim 5, wherein a notch is formed in the hollow portion to reach the peripheral surface of the cooling roll. 7. The peripheral surface of the cooling roll is formed with a spiral groove along the longitudinal direction.
The fixing device according to any one of 2, 3, and 4. 8. A fixing roll having a heating means therein and a pressure roll pressing against the fixing roll are provided, and the recording paper is sandwiched and conveyed between the fixing roll and the pressure roll, and the recording paper on the recording paper is held. In a fixing device for fixing unfixed toner, a cooling roll that contacts the peripheral surface of the pressure roll,
A contacting / separating unit that drives the cooling roll so that the cooling roll can be moved in and out of contact with the pressure roll, a temperature detecting unit provided on the peripheral surface of the pressure roll, and a first surface temperature whose peripheral surface temperature is predetermined. When the temperature rises to the preset temperature, the cooling roll is brought into contact with the pressure roll, and thereafter, when the peripheral surface temperature of the pressure roll drops to the second preset temperature, the cooling roll is escaped from the pressure roll. And a fixing device. 9. A fixing roll having a heating means therein and a pressure roll in pressure contact with the fixing roll are provided, and the recording paper is nipped and conveyed between the fixing roll and the pressure roll, so that the recording paper In a fixing device for fixing unfixed toner, a paper discharge sensor for detecting conveyance of the recording paper after fixing, a cooling roll in contact with a peripheral surface of the pressure roll,
A contact / separation unit that allows the cooling roll to contact and separate from the pressure roll, a temperature detection unit provided on the peripheral surface of the pressure roll, and a first setting in which the peripheral surface temperature of the pressure roll is predetermined. When the temperature is reached, after the detection of the first sheet of recording paper that is detected by or passes through the paper ejection sensor, a control unit that presses the cooling roll against the pressure roll after the recording paper is ejected. A fixing device characterized by being provided.