JP2002082565A - Fixing device and image forming device - Google Patents

Abstract

(57) Abstract: In a fixing device having a fixing roller and a sheet-shaped pressing member, a stable nip width can be obtained even when the thickness of paper to be printed is changed. A fixing device for forming a toner image of a latent image formed on a photoreceptor by electrophotography, transferring the toner image to a sheet, and fixing the transferred toner image, has a heater, and rotates. The fixing roller 21, a sheet-like member 23 that contacts the fixing roller 21 to form a nip portion, a sheet supporting member 27 that cantileverly supports the sheet-like member 23, and a free end of the sheet-like member 23 is higher than a predetermined position. An escape prevention member 30 that regulates the position of the free end of the sheet member 23 so as not to fall down, and prevents the downward movement of the free end of the sheet member 23 when the sheet passes through the nip portion.
Regulated by 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device using a sheet-like member instead of a pressure roller in an image forming apparatus, a copier, a printer, a facsimile machine and a multifunction machine having these functions. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art A conventional fixing device of this type is configured as shown in FIG. As shown in FIG. 6, the fixing device includes a heating fixing roller 1 provided therein with a heater 2 for heating and a pressure fixing roller 3 pressed against the heating fixing roller 1 as main members. In addition, the fixing device includes a heater 2
Temperature detecting means 4 for detecting the surface temperature of the heat fixing roller 1 heated by the heat roller, a guide plate 5 for guiding the sheet between the heat fixing roller 1 and the pressure fixing roller 3, and heat fixing the sheet wound around the heat fixing roller 1. It has a separation claw 6 for separating from the roller 1 and a pair of transport rollers 7 provided on the paper exit side of the fixing device.

The fixing device transfers the sheet on which the toner image has been transferred to the nip portion between the heat fixing roller 1 and the pressure fixing roller 3 via the guide plate 5. After the toner image is fixed on the sheet by being pressed / heated in the nip portion, the sheet is discharged to the outside via the pair of conveying rollers 7. In addition,
When the paper passes through the nip portion, the toner attached to the heat fixing roller 1 is removed by a cleaning pad (not shown).

[0004] The surface temperature of the heat fixing roller 1 is detected by a temperature detecting means 4, and based on the detection result of the temperature detecting means 4, heating control by the heater 2 is performed by a control means.

Conventionally, the fixing device most commonly employs an infrared heater or a halogen heater as a heater and comprises a pair of rollers including a heat fixing roller 1 and a pressure fixing roller 3. However, the pressure fixing roller has a large heat capacity due to a structure in which a silicon rubber layer is formed on a cored bar and a release layer such as a Teflon (registered trademark) tube is formed thereon. Pressure fixing roller 3 even when heating is started by
This tendency is more remarkable due to the recent control that takes into account energy savings.
This is a cause of poor fixing. There was also a disadvantage that the parts cost was high.

Further, in order to secure an appropriate nip width at the nip portion between the heat-fixing roller 1 and the pressure-fixing roller 3, a large pressing force is required. Because of the cause, a nip portion is formed by pressing a sheet-shaped pressing member instead of the pressing and fixing roller 3 against the heating and fixing roller, and an image is formed by passing a sheet through the nip portion. A fixing device or the like for fixing the image on the paper has been devised. Since the fixing device having this configuration is a sheet-shaped member, it is easily heated, and a nip width can be secured.

[0007]

However, in a pressing member using a sheet-like member having such a structure,
In order to apply pressure to the heat fixing roller, for example, it is conceivable to press the sheet-like member against the heat fixing roller from the back side by a pressing spring to secure a pressing force. In this case, the sheet-like member moves up and down in accordance with the thickness of the paper and the nip width changes, so that the types of paper that can be printed are limited.

SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned problems of the prior art, and a fixing device and an image forming apparatus capable of obtaining a stable nip width even when the thickness of paper to be printed is changed. It is intended to provide a device.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a latent image formed on a photoreceptor is formed into a toner image and transferred to a sheet, and the transferred toner image is formed. A fixing roller that rotates with heating means, a sheet-shaped member that contacts the fixing roller to form a nip portion, and a sheet supporting member that cantileverly supports the sheet-shaped member. And an escape prevention member that regulates the position of the free end of the sheet-shaped member so that the free end of the sheet-shaped member does not drop below a predetermined position, and a nip portion between the fixing roller and the sheet-shaped member. The method is characterized in that the sheet is passed while being heated / pressurized to fix the toner image on the sheet. With this configuration, when the sheet passes through the nip portion, the position of the free end of the sheet-shaped member is prevented from lowering more than necessary, and the nip width can be secured.

According to a second aspect of the present invention, in the first aspect, the escape preventing member is configured to be movable, and the vertical position of the sheet-like member is adjusted by moving the escape preventing member. An adjusting means is provided. With this configuration, the nip width can be adjusted.

According to a third aspect of the present invention, in the second aspect of the present invention, the escape preventing member is a roller body having an eccentric rotating shaft, and the adjusting means includes a bearing portion for supporting the rotating shaft. And an adjusting unit for rotating the rotation shaft. With this configuration, the free end of the sheet-like member can be raised and lowered by rotating the roller body, and the nip width can be adjusted.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the rotary shaft is a polygonal prism, and the bearing is a concave portion adapted to the rotary shaft. With this configuration, the rotation of the roller body is regulated by the rotation shaft conforming to the concave portion, the free end of the sheet-shaped member is stabilized, and a click feeling is given when the rotation shaft is manually operated. It becomes possible.

According to a fifth aspect of the present invention, in the invention according to the third or fourth aspect, the adjusting portion is provided on the rotating shaft, and is an index of a rotating position corresponding to a vertical position of the sheet-shaped member. Is provided. With this configuration, the position of the sheet-shaped member can be notified, and information for adjusting the nip width can be given to the user.

According to a sixth aspect of the present invention, in the invention of the fifth aspect, the index is a thickness of a sheet corresponding to a vertical position of the sheet-shaped member.
With this configuration, a nip width corresponding to the thickness of the sheet can be obtained.

According to the seventh aspect of the present invention,
6. In the invention according to any one of items 6, the holding means for holding the fixing roller movably in the direction of contact and separation with respect to the sheet-like member, and a holding means for attaching the fixing roller to the sheet-like member. And a pressurizing means for energizing. With this configuration, the nip pressure can be reduced by moving the fixing roller, and processing when a paper jam occurs in the nip portion is facilitated.

According to an eighth aspect of the present invention, in the invention according to the seventh aspect, the holding means includes a bearing for rotatably holding the fixing roller, and the pressing means via the bearing. Urges the fixing roller in a direction in which the fixing roller comes into contact with the sheet-shaped member. With this configuration, the urging force of the pressing unit can directly act on the fixing roller.

According to a ninth aspect of the present invention, in the invention according to the seventh or eighth aspect, a rotation axis is provided at a portion other than the center axis of the fixing roller in the holding means, and the rotation axis is used as an axis. The holding means is rotatably supported. With this configuration, the fixing roller can be moved toward and away from the sheet member.

According to the tenth aspect, the seventh aspect is provided.
In the inventions according to any one of the first to ninth aspects, the image forming apparatus further includes a moving unit that moves the fixing roller to a contact position where the fixing roller contacts the sheet member or a separation position where the fixing roller is separated from the sheet member. A mating engaging portion is provided on the holding means. With this configuration, it is possible to move the fixing roller in the direction of contact and separation with respect to the sheet member by operating the moving unit.

According to the eleventh aspect of the present invention, there is provided a fixing device for converting a latent image formed on a photoreceptor into a toner image, transferring the toner image to a sheet, and fixing the transferred toner image. A plurality of roller bodies provided with a heating source, a sheet-shaped member that abuts on the fixing roller to form a nip portion, a sheet supporting member that cantileverly supports the sheet-shaped member, and a free end of the sheet-shaped member. An escape preventing member for regulating the position of the free end of the sheet-shaped member so that the sheet does not drop below a predetermined position. The sheet is passed while heating / pressing in a nip portion between the fixing belt and the sheet-shaped member. And fixing the toner image to paper. With this configuration, when the sheet passes through the nip portion, the position of the free end of the sheet-like member is prevented from lowering more than necessary, and the nip width can be secured.

According to the twelfth aspect of the present invention, there is provided a fixing device for converting a latent image formed on a photoreceptor into a toner image, transferring the latent image to a sheet, and fixing the transferred toner image. A cylindrical fixing member made of a member, a driving unit for circulating the fixing member, a heating source in contact with the inside of the fixing member, and a nip portion formed in contact with the heating source via the fixing member. A sheet-like member to be supported, a sheet supporting member that cantileverly supports the sheet-like member, and escape prevention for regulating the position of the free end of the sheet-like member so that the free end of the sheet-like member does not drop below a predetermined position. And fixing the toner image to the sheet by passing the sheet while heating / pressing it in a nip portion between the heating source and the sheet-like member. With this configuration, when the sheet passes through the nip portion, the position of the free end of the sheet-shaped member is prevented from lowering more than necessary, and the nip width can be secured.

According to a thirteenth aspect of the present invention, there is provided an electrophotographic image forming apparatus including the fixing device according to any one of the first to twelfth aspects. With such a configuration, the size and cost of the fixing device due to the use of the sheet-shaped member can be reduced, and the size and cost of the image forming apparatus can be reduced. Further, the fixing operation can be performed stably.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. Here, a facsimile machine is taken as an example of the image forming apparatus in the present embodiment.

FIG. 1 is a sectional view showing a schematic configuration of a facsimile apparatus according to an embodiment of the present invention. In the facsimile apparatus (apparatus main body 10) shown in FIG. 1, a latent image is formed on a photoconductor 12 by an optical writing device 11 that scans a laser beam L modulated based on image data. The process cartridge 13 has the photoconductor 12 therein,
It accommodates various process devices for forming images by electrophotography, and is configured to be detachable from the device main body 10. The toner image formed on the photoconductor 12 is transferred onto the paper stored in the paper cassette 14 and fed and conveyed by the paper feed roller 15 and the like by the transfer roller 16 that contacts the photoconductor 12. The toner image transferred to the paper is fixed by passing through the fixing device 20, and the conveyance roller pair 1
The paper is conveyed to the paper discharge tray 18 by the printer 7.

The original set on the original placing table is discharged to the outside by passing through the contact sensor 19 by the transport system. At this time, the image of the document is optically read by the contact sensor 19 when passing through the contact sensor 19. The image data read by the contact sensor 19 is transmitted and output to the outside. Further, image data received and input from outside or image data read by the above-described contact sensor 19 is sent to the optical writing device 11.

In the optical writing device 11, the surface of the photoconductor 12 is irradiated with a laser beam L modulated based on image data to form an electrostatic latent image on the surface of the photoconductor 12. A toner image is formed by attaching toner to the electrostatic latent image, and the toner image is transferred to a sheet by a transfer roller. Then, the toner image is fixed on the sheet by pressurization / heating by the fixing device 20, and is discharged to the outside by the conveying roller pair 17.

FIG. 2 is a side view showing a schematic configuration of a fixing device included in the facsimile apparatus shown in FIG.
FIG. 2A shows the contact position of the fixing roller with the sheet member, and FIG.
(B) is a state of a separation position.

In FIG. 2, 21 is a fixing roller, 22 is a heater, 23 is a sheet-like member serving as a pressing member, and 24 is a sheet-like member.
Holding means for holding the fixing roller 21 by a bearing portion 24a, a housing rotatable around a shaft 24b as a support shaft,
Reference numeral 25 denotes a transmission gear for transmitting a driving force from a driving unit (not shown) that rotationally drives the fixing roller 21. Reference numeral 26 denotes a transmission gear provided between the housing 24 and the housing to urge the fixing roller 21 against the sheet-like member 23. Pressurizing means, 27 is a sheet-like member 2
Reference numeral 28 denotes a sheet supporting member for supporting the sheet member 3 and a stopper member for the sheet-like member 23 attached to the supporting member.

Reference numeral 29 denotes moving means for moving the fixing roller 21 to a contact position where a nip portion is formed between the sheet members 23 and a fixing position where the fixing roller 21 is separated from the sheet members 23. One end of the moving means 29 is engaged with an engaging claw 24c provided on the housing 24,
The other end is provided with a drive unit (not shown) for moving the contact position and the separation position. Further, in the direction in which the housing 24 is urged by the pressurizing means 26, the one-side pressure at the nip is 0.5 to 10 (9.8).
N) and a locking means (not shown) for locking at a position as shown in FIG.

Reference numeral 30 denotes an escape preventing member. This escape prevention member 30 is located downstream of the nip portion in the paper transport direction.
And it is arranged on the back side of the free end of the sheet-like member 23. When the fixing roller 21 is moved to the contact position by the moving means 29, the free end of the sheet member 23 is lowered by the pressure from the fixing roller 21 as shown in FIG. Contact 30. That is, the position of the free end of the sheet-like member 23 is
Regulated by 0.

In the apparatus shown in FIG. 2, the sheet-like member 23 used in the fixing device 20 is made of a heat-resistant resin such as a rigid fluororesin or polyimide, or a heat-resistant and rigid base material coated with a fluororesin. A metal plate is applied to the base material or a metal plate (iron having rigidity,
Copper or the like). Further, the base material may be configured to contain bubbles in consideration of heat storage properties.

The sheet P to which the toner image has been transferred is fixed to the fixing device 2
In the nip portion between the fixing roller 21 and the sheet-like member 23, the toner image is fixed by heating / pressing. At this time, the fixing roller 21 is heated to a temperature at which fixing can be performed by the heater 22 of the heating means, is moved to a contact position with the sheet-like member 23 by the moving means 29, and is rotationally driven by the driving means for carrying the sheet. Have been. The fixing process is performed by the sheet P passing through the nip portion.

FIG. 3 is a front view showing the structure of the escape preventing member. Reference numeral 31 denotes a rotating shaft 32 at a position deviated from the center axis.
5 shows an eccentric roller having The rotating shaft 32 is a quadrangular prism having a square bottom surface. The rotating shaft 32 is arranged such that one diagonal of the square of the rotating shaft 32 passes through the center of the eccentric roller 31.
Is set. Bearings 33, 33 are provided in the lower part on both sides of the free end of the sheet-like member 23, and the receiving part on which the rotating shafts 32, 32 are mounted has an angle of 9 degrees.
It is formed in a V-shape of 0 °.

The eccentric roller 31 is attached to the bearings 33, 33.
Is placed, the free end of the sheet-like member 23 comes into contact with the eccentric roller 31.

The rotating shaft 32 on one side of the eccentric roller 31
Is provided with a dial 34 having a rotation axis 32 as a central axis. The dial 34 is rotated by a user.

When the corner of the rotating shaft 32 close to the center axis of the eccentric roller 31 is in contact with the bearings 33, 33, the sheet-like member 23 is located closest to the rotating shaft 32 as shown in FIG. Will be located. Then, the dial 34 is rotated by 90 °, and the next corner portion is set to the bearings 33, 33.
, And stops with a click feeling.
3 is lifted. As a result, the winding angle of the sheet-like member 23 around the fixing roller 21 increases before rotation, and
The nip width can be secured. In addition, dial 3
When the next corner portion is fitted to the bearings 33, 33 by rotating the rotating member 4 by 90 °, the sheet-like member 23 is located at the position farthest from the rotating shaft 32 as shown in FIG. The nip width can be secured. Thus, the nip width can be switched by operating the dial 34.

The dial 34 displays the paper type, environment, and the like so that the user can determine the position where the corner of the rotating shaft 32 is fitted to the bearings 33, 33. In the present embodiment, for example, the sheet-like member 23 is selected at the lowermost position for thick paper, the sheet-like member 23 is selected at the uppermost position for thin paper, and the sheet-like member 23 is selected for plain paper. "Thick paper", "plain paper", and "thin paper" are displayed so that 23 is selected as an intermediate position.

According to the present embodiment configured as described above,
Since the eccentric roller 31 abuts on the free end of the sheet member 23, the eccentric roller 31 functions as an escape preventing member, and regulates the vertical movement of the sheet member 23 when the sheet passes through the nip portion. The width can be secured. Further, by rotating the eccentric roller 31, the vertical position of the sheet-like member 23 can be changed, and the nip width can be adjusted by a dial operation of the user.

In the present embodiment, the rotation of the eccentric roller 31 causes the sheet member 23 to move up and down. However, the present invention is not limited to this.
An escape prevention member may be provided at the free end of 3 and the escape prevention member may be configured to be slidable up, down, left, and right to adjust the position.

The fixing roller 2 is moved by the moving means 29.
By separating the sheet member 1 from the sheet member 23, the nip portion of the sheet member 23 abutting on the same surface against the rotation of the fixing roller 21 is worn, and the deformation of the sheet member 23 can be reduced.

Further, the stopper member 28 provided with a gap on the back surface side of the sheet member 23 prevents the sheet member 23 from being deformed due to a trouble such as a paper jam occurring in the fixing device, particularly at the nip portion. Can be prevented. The sheet-like member 23 may be a structural part having a certain degree of heat resistance, such as a polycarbonate resin or an ABS resin. The sheet-like member 23 is formed of a member used for an apparatus housing, and is formed integrally with the sheet support member 27. This makes it possible to reduce the number of parts.

Further, the fixing roller 2 is moved by the moving means 29.
Since the sheet 1 can be separated from the sheet-like member 23, it is possible to smoothly perform processing such as paper jam occurring in the nip portion. Here, when the fixing roller 21 is separated from the sheet-like member 23, the sheet-like member 2
3 may be moved, but in that case, the escape prevention member 30 needs to be retracted to a position where it does not come into contact with the sheet-like member 23. However, in the present embodiment, in order to move the fixing roller 21,
There is no need to provide a means for saving 0.

[0042]

According to the present invention configured as described above, the position of the free end of the sheet-like member is prevented from lowering unnecessarily when the sheet passes through the nip portion,
The nip width can be secured. As a result, stable fixing properties can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration of a fixing device included in the facsimile apparatus shown in FIG. 1, in which (a) is a contact position of a fixing roller with a sheet member, and (b) is a side view showing a state of a separation position.

FIG. 3 is a front view showing a configuration of an escape prevention member.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a side view showing a state in which the dial is rotated by 180 ° in the state shown in FIG. 4;

FIG. 6 is a cross-sectional view illustrating a schematic configuration of a fixing device included in a conventional facsimile machine.

[Explanation of symbols]

 Reference Signs List 20 fixing device 21 fixing roller 23 sheet member 24 housing 24a engaging claw 25 transmission gear 26 pressing means 27 sheet support material 28 stopper member 29 moving means 30 escape prevention member 31 eccentric roller 32 rotating shaft 33 bearing 34 dial

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Kamijo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kota Takenaka 1-3-6 Nakamagome, Ota-ku, Tokyo Company Ricoh F-term (reference) 2H033 AA47 BB33 BB34 BB39

Claims (13)

[Claims] 1. A fixing device for converting a latent image formed on a photoreceptor into a toner image, transferring the toner image to a sheet, and fixing the transferred toner image, comprising: a fixing roller rotating with heating means; A sheet-shaped member that contacts the fixing roller to form a nip portion, a sheet supporting member that cantileverly supports the sheet-shaped member, and the sheet so that a free end of the sheet-shaped member does not fall below a predetermined position. An escape preventing member for regulating a position of a free end of the sheet-shaped member, wherein the sheet is passed through the nip portion between the fixing roller and the sheet-shaped member while being heated / pressurized to fix the toner image on the sheet. Characteristic fixing device. 2. The escape preventing member is configured to be movable,
The fixing device according to claim 1, further comprising an adjustment unit configured to adjust the vertical position of the sheet-shaped member by moving the escape prevention member. 3. The method according to claim 1, wherein the escape preventing member is a roller body having an eccentric rotating shaft, and the adjusting means includes a bearing portion for supporting the rotating shaft and an adjusting portion for rotating the rotating shaft. 3. The fixing device according to claim 2, wherein: 4. The fixing device according to claim 3, wherein the rotating shaft is a polygonal column, and the bearing is a concave portion adapted to the rotating shaft. 5. The adjusting unit is provided on the rotating shaft,
5. The fixing device according to claim 3, further comprising a dial member displaying an index of a rotational position corresponding to a vertical position of the sheet member. 6. The fixing device according to claim 5, wherein the index is a thickness of a sheet corresponding to a vertical position of the sheet member. 7. A holding means for holding the fixing roller movably in the direction of contacting and separating from the sheet-like member, and a pressing means for urging the fixing roller in a direction for bringing the fixing roller into contact with the sheet-like member. The fixing device according to claim 1, further comprising: 8. The holding unit includes the bearing unit that rotatably holds the fixing roller, and the pressing unit presses the fixing roller through the bearing unit in a direction in which the fixing roller comes into contact with the sheet-shaped member. 8. The method according to claim 7, wherein the urging is performed.
The fixing device according to the item. 9. The image forming apparatus according to claim 7, wherein a rotation axis is provided at a position other than a center axis of the fixing roller in the holding means, and the holding means is rotatably supported about the rotation axis. Or the fixing device according to 8. 10. A moving means for moving the fixing roller to a contact position where the fixing roller contacts the sheet member or a separating position for separating the fixing roller from the sheet member. The fixing device according to claim 7, wherein an engagement portion is provided on the holding unit. 11. A fixing device for converting a latent image formed on a photoreceptor into a toner image, transferring the toner image to a sheet, and fixing the transferred toner image, wherein at least one of the plurality of heat sources is provided with a heating source. A roller member, a sheet-shaped member that contacts the fixing roller to form a nip portion, a sheet supporting member that cantileverly supports the sheet-shaped member, and a free end of the sheet-shaped member does not fall below a predetermined position. An escape preventing member for regulating a position of a free end of the sheet-shaped member, and fixing the toner image onto the sheet by passing the sheet while heating / pressing it in a nip portion between the fixing belt and the sheet-shaped member. A fixing device. 12. A fixing device for converting a latent image formed on a photoreceptor into a toner image, transferring the toner image to a sheet, and fixing the transferred toner image, wherein the cylindrical fixing member is made of a flexible member. A driving unit that circulates and moves the fixing member; a heating source that contacts the inside of the fixing member; a sheet-shaped member that contacts the heating source via the fixing member to form a nip; A sheet support member for cantilevering the member, and an escape prevention member for regulating the position of the free end of the sheet-shaped member so that the free end of the sheet-shaped member does not drop below a predetermined position; A fixing device, wherein the toner image is fixed on the sheet by passing the sheet while heating / pressing in a nip portion between the sheet members. 13. An electrophotographic image forming apparatus, comprising: the fixing device according to claim 1. Description: