JP2002244463A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device constituted to restrain energy loss caused by enlargement of motor by restraining the device and the motor from getting larger. SOLUTION: This image forming device is provided with an image forming means 2 forming an image on a sheet S and a fixing device 4 thermally fixing the image by heating the sheet on which the image is formed. The fixing device 4 is provided with at least one roller member (coating roller 10 and cleaning roller 70), and the surface of the roller member consists of an elastic body (silicone rubber 10a). Then, the device 4 is provided with flanges 26 and 74 smaller than the outside diameter of the roller member, coming into contact with the elastic body and resisting the thermal expansion of the elastic body at both ends of the roller member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for a printer, a facsimile, a copying machine, or a multifunction machine having these functions.

[0002]

2. Description of the Related Art For example, in an image forming apparatus such as a copying machine, a printer, a facsimile, or the like, a recording material (transfer material, photosensitive paper, photosensitive paper, A device for thermally fixing an unfixed toner image formed and carried on a paper sheet such as an electrostatic recording paper or a printing paper in a transfer method (indirect method) or a direct method in accordance with target image information is widely used. ing.

In such an image forming apparatus, various elastic rollers are used in the fixing section.

In the case of a relatively low-speed and low-cost one, a pressure roller urged against a fixing roller is coated with a fluorine-based resin on a surface layer of low-hardness rubber or foam, or a tube is covered. Are used. this is,
It is better to increase the nip width between both rollers as much as possible due to the elastic deformation of the rollers, to secure time to transmit heat to the sheet, and to set low thermal conductivity so that heat from the fixing roller is not taken to the pressure roller side. This is because it is preferable.

[0005] Further, among high-speed and high-productivity products, an oil application roller for applying silicone oil, which is a release agent, onto a fixing roller is urged against the fixing roller. Even in such an oil application roller, it is necessary to apply oil uniformly in the longitudinal direction.
Soft rubber is used for the surface layer and a foam is used for the inside.

A web pressed by a cleaning roller or a roller is used to remove paper dust and toner adhering to the fixing roller. However, these rollers also need to apply uniform pressure in the longitudinal direction to the roller portion in contact with the fixing roller. Therefore, soft rubber is used for the surface layer and a foam is used for the inside.

However, when a foam or a soft rubber roller is used, the accuracy of alignment between rollers and the balance of pressure on both sides can be reduced, but the coefficient of thermal expansion increases. Then, as shown in FIG. 10, the roller 101 expands due to the heat from the fixing roller, and the expanded portion escapes in the circumferential direction and at the end in the longitudinal direction, so that the roller 101 is deformed into a drum shape. In the case of such a shape, a state in which both ends of the pressing roller 101 are not in contact with each other easily occurs. For this reason, a long roller 101 is used in addition to the use area in anticipation of the amount of deformation, or the amount of deformation is increased by increasing the pressure to take measures.

[0008]

However, in an image forming apparatus using a longer roller or increasing the amount of deformation by increasing the pressure, the size of the apparatus is increased and a motor having a large torque is required as a drive source. Therefore, there is a problem that energy loss is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which the size of the apparatus and the motor are suppressed, and the energy loss due to the increase in the size of the motor is suppressed.

[0010]

In order to solve the above-mentioned problems, a typical configuration of an image forming apparatus according to the present invention includes image forming means for forming an image on a sheet, and heating the sheet on which the image has been formed. Fixing means for heat-fixing, the fixing means having at least one roller-shaped member, the surface of the roller-shaped member is made of an elastic material, and the roller-shaped member is provided at both ends of the roller-shaped member. It has a member which is smaller than the outer diameter and is in contact with the elastic body and resists thermal expansion of the elastic body.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the image forming apparatus according to the present embodiment, FIG. 2 is a cross-sectional view of a fixing device, FIG.
4 is a detailed view illustrating an oil application section, FIG. 5 is a detailed view illustrating an oil application section, and FIG. 6 is an explanatory view of an oil supply section.

First, a schematic configuration of a copying machine will be described with reference to FIG. The copying machine photoelectrically converts image information read by a reader unit 1 having a scanning optical system, and forms an image.
The image forming unit 2 forms an image on the sheet S transferred to the sheet S and fed by the feeding unit 3. The sheet S after image formation is conveyed to a fixing device 4 as fixing means, and heat and pressure are applied to fix the transferred image.

(Reader unit) A document D placed on a document table glass 1a is irradiated with light by a scanning optical system 1b having a light source and a group of reflecting mirrors, and the reflected light is reduced by a reduction lens 1c.
The image is formed on the CCD 1d via the
After the D conversion, the image information is transferred to the memory.
The maximum document size is LTR or A3.

(Feeding Unit) At the lower part of the copying machine, a feeding cassette 3a loaded with sheets S is detachably mounted. A solenoid (not shown) connected to the pickup roller 3c is turned on during standby and turns on the pickup roller 3c.
c is separated from the sheet surface. Next, when feeding the sheet, the solenoid is turned off, and the pickup roller 3c comes into contact with the sheet surface. Then, the first sheet is fed by the pickup roller 3c which is being driven to rotate. The drive of the pickup roller 3c is transmitted by a transport roller 3e via a timing belt.

The picked-up sheet S is nipped and conveyed by a conveying roller 3e and a retard roller 3f.
The transport roller 3e is rotationally driven in the sheet transport direction, and the retard roller 3f is rotationally driven in a direction opposite to the transport direction via a torque limiter (not shown). Therefore, the front end of the first sheet has only one sheet between both rollers.
The torque limiter loses the frictional force between the sheet and the retard roller 3f, and the retard roller 3f rotates in the transport direction.

Next, when the sheets overlap each other, when the sheets reach the holding portion between the conveying roller 3e and the retard roller 3f, the frictional force of the first and second sheets is lost to the torque limiter, and the retard roller 3f is moved in the conveying direction. To reverse
Only the uppermost sheet is separated and fed in advance. Even if a plurality of sheets S are picked up, only the uppermost sheet is separated and fed in advance by the same operation.

By the feeding operation as described above, the stacked sheets can be fed one by one.

(Conveying Unit) The leading end of the sheet S fed by the feeding unit 3 is temporarily stopped by the registration roller 7, and is again fed in accordance with the image formed by the image forming means 2, and is transferred by the transfer unit. Image transfer is performed. The rotational drive of the registration roller 7 is performed by connecting a clutch (not shown).
The control is controlled by a controller of the main body.

(Image Forming Means) The laser light emitting section 2a emits laser light from the image information read by the reader section 1 by a laser driver. Scanning is performed in the generatrix direction of the photosensitive drum 2c by the rotation of the polygon mirror 2b, and a latent image is formed on the drum surface that has been charged in advance by the charger 2d. This latent image is developed by a developing device 2e provided around the photosensitive drum 2c, and a toner image is transferred to the sheet S by a transfer charger 2g.
The toner remaining on the drum surface after the image transfer is removed by the cleaning device 2h.

This apparatus forms the color image by arranging the same image forming means successively in four colors of cyan, magenta, yellow and black, separating the read image into respective colors, and performing multiple transfer. Is what you do.

(Fixing Section) The sheet S on which the toner image has been transferred by the image forming means 2 is guided to a fixing device 4 by a transport belt 5 and passes through a fixing roller 4a and a pressure roller 4b which are fixing members. Heat and pressure are applied to fuse the toner image to sheet S.

Hereinafter, the fixing device 4 will be described in detail with reference to FIG. As shown in FIG. 2, the fixing roller 4a and the pressure roller 4b, which press and convey the sheet S at the nip portion to fix the sheet S, have silicon rubber fixed to a surface layer of an aluminum cored bar. Halogen heaters 15a and 15b as heating sources are arranged inside the gold, and the temperature of the surface layer is detected by the thermistors 16 and 17 which are in contact with the surface layer of silicon rubber.

The controller section (not shown) includes each thermistor 1
The temperatures of 6 and 17 are compared with a preset temperature. If the temperature is lower than the set temperature, each of the halogen heaters 15a and 15b is controlled to be turned on via an AC driver. , Fixing roller 4a, pressure roller 4
The temperature of b is kept constant.

In the fixing device 4, a part of the first pumping roller 11, which is a releasing agent pumping means, is immersed in oil O in an oil pan P, which is a releasing agent storing means for storing silicone oil O, which is a releasing agent. Have been. The second pumping roller 12, which is another releasing agent pumping means, rotates adjacent to the first pumping roller 11, and the third pumping roller 13 rotates adjacent to the second pumping roller 12.

The second pumping roller 12 is rotationally driven by a driving source (not shown).
11. The drive is transmitted to the third pumping roller 13, and the drive is transmitted through the third pumping roller 13 to the application roller 10, which is a release agent applying unit. The second pumping roller 12 also serves as a rotation center for urging the application roller 10 to the fixing roller 4a by the application roller pressing spring 8.

The coating roller 10 is adjacent to the first drawing roller 11, the third drawing roller 13 and the second supply roller, ie, the second drawing roller 12 and the coating roller 10, and is adjacent to the coating roller 10. The oil O sequentially pumped by the third pumping roller 13 which is the first supply roller
Is applied to the surface of the fixing roller 4a. Further, the coating roller 10 has a metering blade 14 as a release agent restricting means made of an elastic body such as fluororubber urged by a spring 19 so as to constantly maintain a constant pressure against the coating roller 10.
Are in contact with each other, and regulates the amount of oil on the application roller 10 to a predetermined value. The oil on the regulated application roller 10 is transferred to the fixing roller 4a, and the oil remaining on the application roller 10 is removed by the cleaning blade 9 together with the toner and paper powder adhering on the fixing roller 4a. It is removed outside the pan P. The removed oil is collected through an oil tank 21 described below through a filter, and is circulated to be reused again.

Next, the oil application section of the fixing device will be described. The amount of oil O pumped by the first pumping roller 11 is regulated to a certain extent by the gap between the first pumping roller 11 and the second pumping roller 12. Normal,
A predetermined gap (approximately 0.1 mm to 0.3 mm) is provided between these pumping rollers 1 and 2, and the amount of oil passage is determined by the gap. It is pumped to the nip between the pumping roller 13 and the second pumping roller 12. Here, the second pumping roller 12 has a groove having a depth of about 0.1 on its surface, and the oil O accumulated in the groove is transferred to the third pumping roller 13. The third pumping roller 13 is in contact with the coating roller 10 so as to slightly enter the coating roller 10 so that the coating layer 10 whose surface layer is made of silicone rubber is not damaged.
The surface of the third pumping roller 13 has a small surface roughness Ra of 3.2. Here, the material of each pumping roller is metal.

Next, the oil O transferred from the third pumping roller 13 is carried on the circumference of the application roller 10 to the metering blade 14 which is a release agent applying means. The oil application roller 10 has an elastic surface made of silicone rubber as described above.
10a, the inside is made of a foamed silicon sponge 10b, which is fixed to a metal core 10c.

The metering blade 14 is rotatable about a rotation center shaft 14a, and is urged against the application roller 10 by a blade urging spring 19 at a constant pressure. Therefore, the oil on the application roller 10
By passing through the contact portion with the fixing roller 4a, the passing amount is regulated to a desired fixed amount, the oil film has an optimal amount, and after passing through this portion, the oil film is transferred onto the fixing roller 4a via a nip portion with the fixing roller 4a. Applied.

As shown in FIG. 3, the length of each roller is determined by the gap assuring flanges at both ends of the first pumping roller 11.
The second pumping roller 12 is longer than 11a, and the third pumping roller 13 is shorter than the second pumping roller 12. The third pumping roller 13 is shorter than the oil application roller 10 and has an end portion tapered so as not to damage the surface rubber of the oil application roller 10. The oil application roller 10 has a maximum sheet size of A3, which is 297 mm in width, and 301 mm in consideration of ± 2 mm variation in sheet position. The metering blade 14 is longer than the oil application roller 10 so that the entire surface can be regulated.

As shown in FIG. 4, at both ends of the oil application roller 10, thin metal plate flanges 26, which are members against the thermal expansion of the silicone rubber 10a, are arranged via kintings 27. Since the flange 26 is slightly smaller than the outer diameter of the oil application roller 10, it does not come into contact with the fixing roller 4a or the metering blade 14. Further, the outer diameter portion of the flange 26 is dish-shaped, and has increased strength against elongation in the longitudinal direction, thereby ensuring contact with the silicone rubber 10a.

As shown in FIG. 5, it is conceivable to use a flange 28 using a thick plate in order to increase the strength instead of the flange 26.
The oil O1 that has entered the slight gap between the oil application roller 10 and the metal oiling roller 14 flows along the metering blade 14 to the back side due to surface tension, so that the oil at the end of the oil application roller 10 increases in a collar shape. Since this phenomenon appears as uneven oil in the image, in the present embodiment, the amount of oil entering the gap between the metering blade 14 and the flange 26 is reduced by using the thin flange 26.

Every time the pumped oil O is regulated by each roller, the surplus oil escapes toward the end, and is adhered to the end surface due to the viscosity of the oil. More oil. Therefore, the length of the third pumping roller 13 is shorter by 6 mm on one side than the oil application roller 10 in anticipation of the large amount of oil at the end, so that the oil on the oil application roller is uniformly applied over the entire surface. ing.

The thermistor 18 is arranged in the oil, and the temperature of the oil is detected by the controller 32, and the sheet heater H1 is energized via an AC driver so as to be constant with respect to the set temperature. Therefore, it is possible to secure the fixing property at the time of starting the machine and to prevent a change in gloss caused by a change in the amount of applied oil due to the viscosity of the oil.

FIG. 6 is a side view of the oil pan P. The float 20 is floating on the oil O in the oil pan P. The float 20 is rotatably supported about a shaft 21 and moves up and down according to the level of the oil O, and the flag 22 disposed on the opposite surface of the float 20 also rotates at the same time. When the oil O is consumed and the amount becomes small, the float 20 is lowered and the flag 22 is raised, so that the sensor 23 cannot detect the flag 22. The signal is detected by the controller 32 of the main body and the oil pump 24 is operated. The oil pump 24 pumps the oil O from the oil tank 25 disposed below to the oil pan P. When the float 20 rises and the flag 22 falls and the sensor 23 detects the flag 22, the operation of the oil pump 24 is stopped. The level of the oil O in the oil pan P is kept constant.

The oil containing the offset toner and the paper dust scraped off by the cleaning blade as described above falls into the collecting pan 30. The oil collected in the collecting pan 30 is cleaned of dirt by the filter 31, returned to the oil tank 25 again, circulated and used.

[Second Embodiment] Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG.
Is a detailed view of the pressure roller according to the present embodiment, and FIG. 8 is a detailed view of the pressure roller. Portions having the same functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 7, the image forming apparatus according to this embodiment has a pressure roller having flanges 51 at both ends in the longitudinal direction instead of the pressure roller 4b in the above embodiment.
50 is used. The pressure roller 50 is a surface fluorine tube
52, silicon foam material 53 inside, core bar to which it is fixed
Consists of 54.

Since the halogen heater 15a, which is a heat source, is provided only on the fixing roller 4a side, the pressure roller 50 is deformed by thermal expansion due to heat received from the fixing roller 4a side. At this time, flanges 51 are provided at both ends of the pressing roller 50 in the longitudinal direction.
By preventing the drum-shaped deformation by restricting the longitudinal deformation due to the thermal expansion of the pressure roller 50 and expanding in the radial direction, it is possible to prevent the central pressure from increasing. Prevents sheet wrinkling and enables stable conveyance.

As shown in FIG. 8, a spring 55 may be provided to urge the flange 51 against the pressure roller 50. If it takes time for the temperature of the pressure roller 50 to stabilize, the spring 19 expands and contracts in accordance with the difference between the amount of expansion immediately after the start-up of the device and after the temperature has stabilized, and the heat of the pressure roller 50 The expansion in the radial direction is restricted by restricting the deformation in the longitudinal direction due to the expansion. Accordingly, drum-shaped deformation can be prevented regardless of the temperature of the pressure roller 50, and the roller shape can be stabilized.

[Third Embodiment] Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG.
FIG. 3 is a detailed view of a cleaning unit of the present embodiment. Portions having the same functions as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 9, in the present embodiment, the prevention of the drum-shaped deformation of the fixing roller 4a of the first embodiment is applied to the cleaning roller 70 of the cleaning devices 6a and 6b. The cleaning roller 70 is a cleaning web
71 is pressed against the fixing roller 4a to clean offset toner and paper dust attached to the fixing roller 4a or the pressure roller 4b.

The cleaning web 71 is delivered from the delivery roller 75 and wound up by the take-up roller 76, and is operated by the controller of the main body at a timing of once every several sheets according to the paper size, so that a fresh surface is always fixed. It is in contact with the roller 4a. The cleaning roller 70 is made of foamed silicon 72 made of metal core 73.
And a flange 74 slightly smaller than the outer diameter of the cleaning roller 70 is disposed at both ends. The length of the cleaning roller 70 is 301 mm which is longer by 2 mm at both ends than A3 which is the maximum size.

As a result, the drum-like thermal expansion of the cleaning roller 70 can be prevented by the heat from the fixing roller 4a, so that it is not necessary to increase the pressure to secure the pressing over the entire length. Since the pressure of the cleaning roller 70 directly increases the driving force of the fixing roller 4a, energy can be saved by not using a motor having an excessive torque, and the life of the fixing roller 4a or the pressure roller 4b can be extended. Has also contributed.

In the above embodiment, the cleaning roller 70 around the fixing roller 4a has been described. However, a cleaning roller around a belt-like member such as a fixing belt may be used.

[0046]

As described above, according to the present invention, in an image forming apparatus such as a printer, a facsimile, a copying machine, or a multifunction machine having these functions, an image forming means for forming an image on a sheet and an image are formed. The fixing means for heating and thermally fixing the sheet and the surface of the roller-like member in the fixing means are made of an elastic body, and both ends of the fixing means are smaller than the outer diameter and come into contact with the elastic body so that the heat of the elastic body is reduced. It has a member that resists expansion.

As a result, it is possible to suppress an increase in the overall length of the apparatus and the roller length, and to avoid unnecessary pressing, thereby suppressing energy loss.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus according to a first embodiment.

FIG. 2 is a cross-sectional view of a fixing device.

FIG. 3 is a configuration diagram of an oil application unit.

FIG. 4 is a detailed view showing an oil application section.

FIG. 5 is a detailed view illustrating an oil application section.

FIG. 6 is an explanatory diagram of an oil supply unit.

FIG. 7 is a detailed view of a pressure roller according to a second embodiment.

FIG. 8 is a detailed view of a pressure roller.

FIG. 9 is a detailed view of a cleaning unit according to the third embodiment.

FIG. 10 is a detailed view of a conventional pressure roller.

[Explanation of symbols]

 D: Document H1: Sheet heater O: Silicon oil O1: Oil P: Oil pan S: Sheet 1: Leader unit 1a: Platen glass 1b: Scanning optical system 1c: Reduction lens 1d: CCD 2: Image forming means 2a: Laser emitting unit 2b Polygon mirror 2c Photosensitive drum 2d Charger 2e Developing device 2g Transfer charger 2h Cleaning unit 3 Feeding unit 3a Feeding cassette 3c Pickup roller 3e Transport roller 3f Retard roller DESCRIPTION OF SYMBOLS 4 ... Fixing device 4a ... Fixing roller 4b ... Pressure roller 5 ... Conveying belt 6a ... Cleaning device 6b ... Cleaning device 7 ... Registration roller 8 ... Application roller pressurization spring 9 ... Cleaning blade 10 ... Application roller 10a ... Silicon rubber 10b ... Foamed silicon sponge 10c ... metal core 11 ... first Pumping roller 11a… Flange part 12… Second pumping roller 13… Third pumping roller 14… Metalling blade 14a… Rotation center axis 15a… Halogen heater 15b… Halogen heater 16… Thermistor 17… Thermistor 18… Thermistor 19… Spring 20… Float 21… Oil tank 22… Flag 23… Sensor 24… Oil pump 25… Oil tank 26… Flange 27… Kind 28… Flange 30… Recovery pan 31… Filter 32… Controller 50… Pressure roller 51… Flange 52… Fluorine Tube 53… Silicon foam 54… Core 55… Spring 70… Cleaning roller 71… Cleaning web 72… Silicone foam 73… Core 74… Flange 75… Delivery roller 76… Winding roller 101… Roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F16C 13/00 F16C 13/00 C FF term (reference) 2H033 AA08 AA09 AA32 AA36 BA42 BA43 BA44 BA45 BA46 BA49 BA51 BA54 BA55 BA56 BA57 BB06 BB28 BB30 3J103 AA02 AA74 BA22 BA34 FA01 FA03 GA02 GA57 GA58 GA60 HA04 HA12 4F040 AA05 AB20 AC01 BA14 CB03 CB06 CB33

Claims (7)

[Claims] 1. An image forming means for forming an image on a sheet, and a fixing means for heating and thermally fixing the sheet on which the image is formed, wherein the fixing means has at least one roller-shaped member. The surface of the roller-shaped member is made of an elastic body, and has a member which is smaller than the outer diameter of the roller-shaped member and is in contact with the elastic body at both ends of the roller-shaped member to oppose the thermal expansion of the elastic body. Image forming apparatus. 2. The fixing device according to claim 1, wherein the roller-shaped member is an application roller that is adjacent to the fixing member and that applies a release agent to the fixing member in order to easily release the sheet from the fixing member of the fixing unit. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the roller member is a cleaning roller that cleans the fixing member directly or via a web. 4. The image forming apparatus according to claim 1, wherein the member against the thermal expansion has a dish shape. 5. The image forming apparatus according to claim 1, wherein the member opposing the thermal expansion biases an elastic body. 6. The second supply roller, which is adjacent to the application roller and supplies the release agent, has a surface roughness smaller than that of the application roller, and is disposed adjacent to and upstream of the first supply roller. 3. The image forming apparatus according to claim 2, wherein the roller has a larger surface roughness. 7. The image forming apparatus according to claim 2, wherein the first supply roller is shorter than the application roller, and an end of the first supply roller is tapered.