Patent Application
20120195655
The present application is related to, claims priority from and incorporates by reference Japanese Patent Application No. 2011-017247, filed on Jan. 28, 2011.
The present application relates to a fuser used in an electrographic type image forming device and the image forming device that includes the fuser.
A conventional image forming device using an electrographic method forms an electrostatic latent image that corresponds to image information by exposing a surface of a photosensitive drum using an exposure head, such as a light emitting diode (LED) and the like after uniformly charging the surface of the photosensitive drum by a charging roller. Then, a toner image is formed by electrostatically attaching a thin layer of toner on a development roller to the electrostatic image. After transferring the toner image onto a sheet carried by a carrying belt using a transfer roller, an image is formed on the sheet by fixing the toner image using a fuser.
This type of image forming device uses a belt heating type fuser. In such a fuser, a fusion belt formed by an endless belt is heated, and a fusion roller is pressed by a pressure application roller facing across the fusion belt, thereby forming a nip part. The carried sheet is pinched by the nip part, and the toner image is fixed onto the sheet by heat and pressure. See Japanese Laid-Open Patent Application No. 2009-151115 (paragraphs 0012-0020, 0028 and FIG. 1).
However, in the above-described conventional technology, because the toner image is fixed onto the sheet by pinching the sheet that has been carried, by the nip part formed by pressing the fusion roller with the pressure application roller facing across the fusion belt, there is a problem that excess reverse curling occurs on the sheet after the fusion if a temperature difference between the pressure application roller and the fusion belt and fusion roller is large at the time of fusion.
Such a sheet with a large amount of reverse curling causes carrying ability of the sheet after fusion and stackability of the sheet on a stacker to be reduced. The present application is made in consideration of solving the above-described problem and has an object to provide a device that suppresses the reverse curling amount at the time of fusion at the fuser.
In order to solve the above subjects, a fuser of the present invention includes a first roller that includes a first elastic layer, a belt member provided on, and rotates around, the first roller, a second roller that includes a second elastic layer and that forms a nip part by pressing, through the belt member, the first roller, and a heating member that heats the belt member. A thickness of the second elastic layer of the second roller is less than a thickness of the first elastic layer of the first roller. In another view, an image forming device of the present invention includes the fuser discussed above.
As a result, the present application as an advantage to increase a surface temperature of the pressure application roller to a temperature needed to start printing by increasing a speed to raise the temperature of the second roller (for example, a pressure application roller) and to suppress the reverse curling amount generated on a sheet by reducing the temperature difference between the first roller (for example, a fusion roller) and the pressure application roller at the time of fusion.
Embodiments of a fuser and an image forming device according to the present specification are explained below with reference to the drawings.
In
A sheet supply mechanism that is formed by sheet supply rollers 5a and 5b and a separation piece 6 and that separates and feeds each of the sheets P from the sheet cassette 2 is provided at a connection part between the sheet carrying path 4 and the sheet cassette 2. Carrying rollers 7 that pinch and carry each sheet P that is fed from the sheet supply mechanism and registration rollers 8 that correct diagonal traveling of and carry the sheet P carried by the carrying rollers 7 are provided on the downstream side of the sheet supply roller 5b in the carrying direction of the sheet P (“sheet carrying direction”).
A carrying belt 9 that carries the sheet P carried by the registration rollers 8 is positioned on the downstream side of the registration rollers 8 in the sheet carrying path. Above a top surface part of the paralleled part of the carrying belt 9, a plurality of image forming parts 11 are provided along the carrying belt 9. An exposure head 12 for forming an electrostatic latent image is provided above each image forming part 11. On the opposite side of the top surface part of the carrying belt 9, a transfer roller 13 is provided that transfers a toner image as a developer image formed by the image forming part 11 onto the sheet P. A fuser 14 that fixes the toner image transferred on the sheet P is provided on the downstream side of the transfer belt 9 in the sheet carrying direction. Moreover, a plurality of ejection rollers 16a and 16b that pinch and carry the sheet P ejected from the fuser 14 to the stacker 3 on a top cover 15 are arranged on the downstream side of the fuser 14 in the sheet carrying direction.
In the printer 1 of the present embodiment, there are four independent image forming parts 11k, 11y, 11m and 11c that accommodate toners T in black (K), yellow (Y), magenta (M) and cyan (C), respectively, as developers and that are provided in the order along the sheet carrying direction to form toner images. Because these four image forming parts 11 have the same configuration, only one image forming part 11 is explained below.
The image forming part 11 includes a photosensitive body, such as photosensitive drum 18, on which an electrostatic latent image is formed by the exposure head 12, a charging roller 19 that uniformly charges the photosensitive drum 18, a development roller 20 that develops an image by attaching the toner T to the electrostatic latent image on the photosensitive drum 18, a supply roller 21 that supplies the toner T to the development roller 20, a toner cartridge 22 that accommodates the toner T of a set color, a cleaning blade 23 that removes the toner T remained on the photosensitive drum 18 after transfer by scraping off the toner T from the photosensitive drum 18, and the like. In addition, each image forming part 11 is integrally configured and is removably installed in the printer 1. Therefore, the top cover 15 of the printer 1 is configured to be able to open and close.
The exposure head 12 as an exposure device is supported by the top cover 15 and is provided above, and to face, the photosensitive drum 18. The exposure head 12 includes a light emitting body such as light emitting diode (LED) light that emits light, laser light and the like, and forms an electrostatic latent image on the surface of the photosensitive drum 18 based on image information. The transfer roller 13 as a transfer device is provided to face the photosensitive drum 18 across the carrying belt 9 and transfers, by a transfer voltage applied thereto, the toner image formed on the photosensitive drum 18 onto the sheet P carried by the carrying belt 9.
The fuser 14 of the present embodiment is a belt heating type device and is configured from a pressure application roller 30 (as the second roller) and a fusion belt unit 31 as shown in
The pressure application roller 30 and the fusion roller 32 of the fusion belt unit 31 are arranged to face, and parallel with, each other across the fusion belt 33. The pressure application roller 30 presses the fusion belt unit 31 at a predetermined pressure by a pressure mechanism (not shown) provided to the pressure application roller. As a result, a nip part is formed between the fusion belt 33 and the pressure application roller 30 with a predetermined nip width in the sheet carrying direction.
A belt temperature sensor 36 as a belt temperature detection device configured from a thermistor or the like that slides on, and detects a temperature of, an inner circumferential surface of the fusion belt 33 is provided between the heater 34 of the fusion device 14 and the nip part and on the upstream side of, and near, the nip part in the rotational direction (clockwise direction in
As shown in
The core shaft 30a of the pressure application roller 30 of the present embodiment is configured from a pipe made of an aluminum material (A5052) with a thickness t1 (maybe referred to as “core shaft thickness t1”) and a length of 230 mm. A silicone rubber layer having a thickness t2 (maybe referred to as “elastic layer thickness t2”) is formed as an elastic layer 30b on the outer circumferential surface of the pipe. The surface of the pressure application roller 30 is covered by a perfluoroalkyl vinyl ether copolymer (PFA) resin tube, which is a type of fluorine resin, as the release layer 30c having a thickens of 40 μm. The pressure application roller 30 has an outer diameter of 36 mm. The thickness t1 of the core shaft 30a and the thickness t2 of the elastic layer 30b are discussed later.
As shown in
As shown in
The heater holder 35 is positioned distant from the fusion roller 32 on the opposite side of the pressure application roller 30 and to face the fuser roller 32. The heater holder 35 supports the fusion belt 33 with the fusion roller 32 so that the fusion belt 33 is rotatably tensioned. The heater holder 35 is configured by a resin with high heat resistance, such as polyether ether ketone (PEEK), liquid crystal polymer (LCP) or the like. The heater 34 is fixedly supported along a longitudinal direction of, and on a top center part of, the heater holder 35 with a heat resistant adhesive or the like.
As shown in
Moreover, regarding the inner diameter of the fusion belt 33, the time to raise the temperature of the fusion belt 33 increases if a circumferential length of the fusion belt 33 is long, and a space would be insufficient if the circumferential length is short, causing the outer diameter of the fusion roller 32 needed for securing a nip width to be reduced. Therefore, the outer diameter of the fusion 32 is configured to 36 mm, and the inner diameter of the fusion belt 33 is configured to 45 mm. In addition, an output of the heater 34 is configured to 900 W. The pressure application roller 30 is configured to press the fusion belt 33 at 10 kgf on each side, or the total of 20 kgf, by a pressure mechanism (not shown). Moreover, for the printer 1 of the present embodiment, the print speed is configured to 30 ppm (page/minute) for A4 (portrait), and the warm-up time is configured to 30 seconds.
In
Reference numeral 42 is a high voltage power source that applies voltage to the charging roller 19, the development roller 20, the supply roller 21, the transfer roller 13 and the like based on a command from the controller 40. The charging roller 19, the development roller 20, the supply roller 21 and the like are electrically connected to the high voltage power source 42 when the image forming part is installed in the printer 1.
Reference numeral 43 is a fusion controller that supplies power for heating to the heater 34 of the fuser 14 from a power supply circuit (not shown) and rotates the pressure application roller 30 in the carrying rational direction by supplying power to the fusion motor 38 based on a command from the controller 40.
In addition, a surface temperature of the fusion belt 33 detected by the belt temperature sensor 36, a surface temperature of the pressure application roller 30 detected by the pressure application roller temperature sensor 37, and the like are inputted to the fusion controller 43. The controller 40 turns on and off the power supplied to the heater 34 by the fusion controller 43 based on the surface temperature of the fusion belt 33 inputted to the fusion controller 43 and controls the surface temperature of the fusion belt 33 to be maintained in a predetermined fusion temperature.
Operation of each part during the printing operation of the printer 1 of the present embodiment is explained below. The controller 40 of the printer 1 starts printing in accordance with a print order when the print order is received from a host device. The controller 40 then feeds the sheet P accommodated in the sheet cassette 2 to the sheet carrying path 4 by separating each sheet using the sheet supply rollers 5a and 5b and a separation piece 6 and carries sheet P to the carrying belt 9 using the carrying rollers 7 and the registration rollers 8.
In parallel with this, the controller 40 applies predetermined voltage that is configured in advance to each of rollers in each image forming part 11 and the transfer roller 13 using the high voltage power source 42 and uniformly charges the surface of each photosensitive drum 18 by charging voltage applied to the charge roller 19 of each image forming part 11. The controller 40 then causes each exposure head 12 to emit light in accordance with image information based on the print order and forms an electrostatic latent image on the surface of each photosensitive drum 18 by exposure. The controller 40 develops the electrostatic latent image on the photosensitive drum 18 by attaching to toner T supplied from the supply roller 21 onto the surface of the photosensitive drum 18 using the development roller 20 to form a toner image of the corresponding color on the surface of the photosensitive drum 18.
As the sheet P is carried to the image forming part 11 by the carrying belt 9, toner images in black, yellow, magenta and cyan are sequentially transferred onto the sheet P by transfer voltage applied to the transfer roller 13 while the sheet P passes between the transfer roller 13 and the photosensitive drums 18 in the respective image forming parts 11k, 11y, 11m and 11c, and thereby a color toner image is formed.
As the sheet P with the toner image transferred thereon is carried to the fuser 14, the toner image is fixed to the sheet P by the fuser 14 and is ejected and stacked to the stacker 3 on the top cover 15 by the ejection rollers 16b after being carried by the ejection rollers 16a to complete the print operation.
Fusion operation by the fuser 14 in this case is explained below. First, the controller rotates the fusion motor 38 using the fusion controller 43 in accordance of the start of printing in the printer 1. The controller 40 then rotates a pressure application roller gear of the pressure application roller 30 for the fuser 14 via a drive gear array (not shown) provided in the main body of the printer 1 and causes the fusion belt 33 and the fusion roller 32 to follow and to be rotated by the frictional force at the nip part in accordance with the rotation of the pressure application roller 30.
In addition, the controller 40 supplies power to the heat 34 from the power supply circuit 34 using the fusion controller 43 to generate heat and to heat the fusion belt 33 from the inner circumferential surface side. The temperature of the fusion belt 33 heated by the heater 34 is detected by the belt temperature sensor 36 and is inputted to the fusion controller 43. The fusion controller 43 turns on and off the power that is supplied to the heater 34 from the power supply circuit based on the detected surface temperature of the fusion belt 33 to control the surface temperature of the fusion belt 33 to be maintained at the predetermined fusion temperature.
As the sheet P with the toner image transferred thereon is carried in a state where the surface temperature of the fusion belt 33 is maintained at the predetermined fusion temperature, the sheet P is pinched by the nip part formed by the fusion roller 32 and the pressure application roller 30 via the fusion belt 33. Then the sheet P is heated by the fusion belt 33 at a predetermined fusion temperature and pressed by the pressure application roller 30 at a predetermined pressure. As a result, the toner image is fixed to the sheet P.
In addition, it is preferable that the pressure application roller 30 starts rotating without delay from the time when the heater 34 is turned on because the pressure application roller 30 of the present embodiment does not include a heat generating body. Therefore, in the present embodiment, the pressure application 30 is configured to start rotating at the time when the heater 34 is turned on. Moreover, a target temperature of the fusion belt 33 of the present embodiment is configured to 160° C., and the temperature of the fusion belt 33 is controlled to reach the fusion temperature configured from a predetermined temperature range having the target temperature as a median value at the time of executing fusion after the heater 34 is turned on.
For the belt heating type fuser 14 with the configuration of the present embodiment, the evaluation test indicated below was conducted by changing the thickness t2 (see
As shown in
In the print operation, the print can be started when the temperature of the fusion belt 33 reaches the fusion target temperature from the room temperature. The surface temperature of the pressure application roller 30 that is detected by the pressure roller temperature sensor 37 at this time is called a starting pressure application roller end-point temperature.
For the evaluation test, the fuser 14 with the sample pressure application roller 30 attached therein was installed in the printer 1, and 50 A4-size sheets P (Oki Data Excellent Paper) were fed in the portrait orientation and were continuously printed at 30 pages-per-minute (ppm) with a printer pattern that achieves 5% toner duty after turning on the power and completing warm-up. A reverse curling amount after ejection of the first sheet P and a stacking condition of the 50 sheets P after ejection were configured as evaluation items. In addition, the evaluation was conducted under a high-temperature-high-humidity environment (HH environment), under which the sheet P after fusion becomes easily reverse-curled.
The reverse curling in the present explanation is a state of the sheet P where the sheet P convexly curls with the surface of the sheet P on which the toner T has been fixed facing upward. Evaluation results of each sample pressure application roller 30 according to the above-described evaluation conditions are shown in
As shown in
Explaining in more details, as shown in
As shown in
That is, if the relationship of thicknesses between the elastic layer 30b of the pressure application roller 30 and the elastic layer 32b of the fusion roller 32 is configured to
a. Elastic layer thickness t2 of pressure application roller<Elastic layer thickness t4 of fusion roller (1)
the reverse curling amount at the time of start of printing immediately after the warm-up is controlled at 10 mm or less, resulting in an excellent stacking condition.
In addition, if the relationship of heat capacity of the pressure application roller 30 and heat capacity of the fusion roller 32 is configured to
a. Heat capacity of pressure application roller<Heat capacity of fusion roller (2)
the reverse curling amount at the time of start of printing immediately after the warm-up is controlled at 10 mm or less, resulting in an excellent stacking condition.
As described above, it was understood that a large reverse curling amount occurs when the heat capacity is large and that the reverse curling amount is small when the heat capacity of the heat roller 30 is reduced, even with the same configuration. When the relationship of the elastic layer thickness t4 of the fusion roller 32 and fusibility was studied by another test, occurrence of fusion defects was slightly observed with the elastic layer thickness t4 of 1 mm. Therefore, it is necessary that a more preferred elastic layer thickness t4 of the fusion roller 32 is 2 mm or more.
In addition to the above-described evaluation test, for the fifth to seventh samples (samples 5 to 7) with the same outer diameter and the core shaft thickness t1 of the pressure application roller 30 that has been configured so that a flexure strength to be equalized in response to the elastic layer thickness t2, with the pressure application roller 20 of the second sample as a reference, a similar evaluation test was conducted based on the combination with the above-described fusion roller 32 and the fusion belt 33. The evaluation results are shown in
As shown in
As described above, in the present embodiment, the thickness of the elastic layer 30b of the pressure application roller 30 for the fuser 14 is made less than the thickness of the elastic layer 32b of the fusion roller 32. Therefore, the temperature of the pressure application roller 30 increases fast, and the surface temperature of the pressure application roller 30 is increased, during the warm-up, to the temperature needed for start of printing. As a result, the difference in temperatures of the fusion unit 31 and the pressure application roller 30 at the time of fusion is reduced, and the difference in dryness of the front and back sides of the sheet P are decreased. Accordingly, the fuser 14 that allows the reverse curling amount to be reduced can be provided. In addition, because the temperature increase of the fusion roller 30 is increased, the warm-up time at the time of start of printing is shortened.
Furthermore, the printer 1 of the present embodiment, with the fuser 14, provides excellent sheet carrying ability and stackability for the fusion process after being turned on and recovery from a power saving mode. In addition, the preset embodiment is explained with a sheet heater as the heating member. However, the heater may be a halogen heater 45.
The halogen heater 45 is configured from a halogen lamp 45b as a heat generating body built in a heater cover 45a as shown in
As described above, in the present embodiment, the thickness of the elastic layer of the pressure application roller is made less than the thickness of the elastic layer of the fusion roller in the belt heating type fuser. Therefore, the temperature of the pressure application roller increases fast, and the surface temperature of the pressure application roller is increased to the temperature needed for start of printing during the warm-up. As a result, the difference in temperatures of the fusion unit and the pressure application roller at the time of fusion is reduced. Accordingly, the fuser allows the reverse curling amount to be reduced. In addition, the warm-up time at the time of start of printing is shortened.
The fuser of the present embodiment is explained with reference to
As a result, the nip width is made longer than that in the above-described first embodiment, resulting in improved fusion speed. In addition, the outer diameter of the fusion roller 32 is made small. Therefore, by reducing the heat capacity of the fusion belt unit 31, the warm-up time is decreased. Therefore, in the present embodiment, the print speed is configured to 40 ppm for carrying A4 size paper in the portrait orientation, and the warm-up time is configured to 20 seconds. The fusion belt 33 of the present embodiment, which is similar to the first embodiment. has an inner diameter of 45 mm.
As shown in
In the pad 50 of the present embodiment, the support base 50a is made of an aluminum material (material: A6063), and the elastic material 50b is formed by a silicone rubber. The sliding layer 50c is configured by coating the PFA resin having a thickness of 30 μm, and an arc length of the arc surface 50d is configured to 5 mm.
The configuration of the fusion roller 32 of the present embodiment is similar to the above-described first embodiment. The core shaft 32a is configured from a pipe made of an iron material (material: STKM) with a diameter of 23 mm, a thickness t3 of 1.5 mm (t3=1.5 mm) and a length of 230 mm, and an elastic layer 32b formed by a silicone rubber layer having a thickness t4 of 1 mm (t4=1 mm). The fusion roller 32 has an outer diameter of 26 mm.
The configuration of the pressure application roller 30 of the present embodiment is similar to the first embodiment but different in the following. The core shaft 30a is configured from a pipe formed of an iron material (material: STKM) having a diameter of 28 mm, a thickness t1 of 0.5 mm (t1=50 mm) and a length of 230 mm. A silicone rubber layer having a thickness t2 is formed as an elastic layer 30b. The surface of the pressure application roller 30 is covered by a PFA resin tube as a separation layer 30c having a thickness of 40 μm. The pressure application roller 30 has an outer diameter of 36 mm. The thickness t2 of the elastic layer 30b is discussed later.
Print operation of the printer 1 and fusion operation of the fuser 14 in the present embodiment are the same as those in the above-described first embodiment. Therefore, their explanation is omitted. For the belt heating type fuser 14 with the configuration of the present embodiment, the evaluation test similar to the first embodiment was conducted by changing the thickness t2 of the elastic layer 30b of the pressure application roller 30 to study a configuration for suppressing the reverse curling amount.
As shown in
Evaluation results of each sample pressure application roller 30 according to the above-described evaluation conditions are shown in
Explaining in more details, as shown in
As shown in
That is, if the relationship of thicknesses between the elastic layer 30b of the pressure application roller 30 and the elastic layer 32b of the fusion roller 32 is configured to
a. Elastic layer thickness t2 of pressure application roller<Elastic layer thickness t4 of fusion roller (3)
the reverse curling amount at the time of start of printing immediately after the warm-up is controlled at 10 mm or less, resulting in an excellent stacking condition.
In addition, if the relationship of heat capacity of the pressure application roller 30 and heat capacity of the fusion roller 32 is configured to
a. Heat capacity of pressure application roller<Heat capacity of fusion roller (4)
the reverse curling amount at the time of start of printing immediately after the warm-up is controlled at 10 mm or less, resulting in an excellent stacking condition.
As described above, it was understood that a large reverse curling amount occurs when the heat capacity is large and that the reverse curling amount is small when the heat capacity of the heat roller 30 is reduced, even with the same configuration. When the relationship of the elastic layer thickness t4 of the fusion roller 32 and fusibility was studied by another test, occurrence of fusion defects was slightly observed with the elastic layer thickness t4 of 1 mm. Therefore, it is necessary that a more preferred elastic layer thickness t4 of the fusion roller 32 is 2 mm or more. In the embodiment, the outer diameter of the fusion roller 32 is 25 mm. Therefore, the preferred elastic layer thickness is approximately 8% ore more with respect to the outer diameter.
As described above, similar to the first embodiment, in the present embodiment, the thickness of the elastic layer 30b of the pressure application roller 30 for the fuser 14 is made less than the thickness of the elastic layer 32b of the fusion roller 32. Therefore, the temperature of the pressure application roller 30 increases fast, and the surface temperature of the pressure application roller 30 is increased to the temperature needed for start of printing during the warm-up. As a result, the difference in temperatures of the fusion unit 31 and the pressure application roller 30 at the time of fusion is reduced, and the difference in dryness of the front and back sides of the sheet P. Accordingly, the fuser 14 that allows the reverse curling amount to be reduced can be provided. In addition, because the temperature increase of the fusion roller 30 is increased, the warm-up time at the time of start of printing is shortened.
Furthermore, the printer 1 of the present embodiment, with the fuser 14, provides excellent sheet carrying ability and stackability for the fusion process after being turned on and recovery from a power saving mode.
In addition, in the present embodiment, because of the pad 50 added to the fuser 14, the nip width is configured longer than the first embodiment. Therefore, the fusion speed is improved, and the outer diameter of the fusion roller 32 can be reduced. As a result, the heat capacity of the fusion unit 31 is reduced, and the warm-up time at the time of starting printing is shortened.
As described above, in the present embodiment, the thickness of the elastic layer of the pressure application roller is made less than the thickness of the elastic layer of the fusion roller in the belt heating type fuser, and a pad that presses the pressure application roller via the fusion belt is provided adjacent to the fusion roller. Therefore, the temperature of the pressure application roller increases quickly, and the surface temperature of the pressure application roller is increased to the temperature needed for the start of printing during the warm-up. As a result, the difference in temperatures of the fusion unit and the pressure application roller at the time of fusion is reduced. Accordingly, the fuser allows the reverse curling amount to be reduced. In addition, the warm-up time at the time of start of printing is further shortened.
The present embodiments are not limited to those described above, and various changes and modifications are available without departing from the scope of the invention. In addition, the description of members disclosed in the present application is examples and are not to be limited to the description. Moreover, in each of the above-described embodiments, the print medium is normal paper. However, the medium is not limited to this and may be an overhead projector (OHP) sheet, a card, a post card, a thickness having a weight of about 200 g/m2 or more, an envelope, and a special paper such as a coated paper having a large heat capacity and the like.
Further, in each of the above-described embodiments, the heating member is explained as a sheet heater or a halogen heater. However, the heating member may be a cylindrical heater having a sliding surface against the fusion belt that has approximately the same radius of curvature as that for the fusion belt. Types and shapes of the heating member are not limited. Furthermore, in each of the above-described embodiments, the heater is described as being provided inside the fusion belt. However, the heater may be provided outside the fusion belt.
Concerning the temperature increase of the pressure application roller 30 and the fusion roller 32, there is a high dependability to the thickness of the elastic layer of each roller. Therefore, materials and characteristics of the elastic layers of the pressure application roller 30 and the fusion roller 32 are not limited, although the same material is preferred for stabilizing the heat transfer.
In addition, in the present embodiments, the material of the elastic layers of the pressure application roller 30 and the fusion roller 32 is silicone rubber in consideration of heat tolerance, antifriction, heat resistance and the like. The silicone rubber may be formed by liquid silicone rubber or millable-type silicon rubber. Moreover, a foaming condition of the elastic layer may be a solid state (expansion ratio=1) or a foam state (expansion ratio>1). In the present embodiments, the elastic layer of the pressure application roller 30 is formed by the liquid silicone rubber in the solid state. Further, the elastic layer of the fusion roller 32 is formed by the liquid silicone rubber in the solid state.
In the present embodiments, the foaming condition of the pressure application roller 30 and the fusion roller 32 is in the solid state. However, similar effects can be obtained with the combination of any foaming condition in the present application, as long as the expansion ratio is between 1.0 and 5. Here, the expansion ratio is a ratio of volume expansion of a foam plastic having the same mass in comparison with the foam plastic in the solid state, or refers to a value of an apparent density of the foam plastic divided by a density of a synthetic resin before foaming.
Further, in the present embodiments, the fusion roller 32 is explained to be driven and rotated by the pressure application roller 30. However, if the fusion roller 32 is rotated as the driving side, and if the pressure roller 30 is driven and rotated, the fusion belt 33 is evenly carried by the fusion roller 32 with the elastic layer of the pressure application roller 30 being in the solid state and with the elastic layer of the fusion roller 32 being in the foam state. As a result, an effect, such as stable fusion quality, is obtained.
Furthermore, as explained in the first embodiment, if the core material of the fusion roller 32 and the pressure application roller 30 is aluminum, the thickness of the core is preferably set to 0.5 to 2.0 mm. In addition, more effects are obtained by setting the thickness of the elastic layer of the pressure application roller 30 by 0.4 to 0.8 times of the thickness of the elastic layer of the fusion roller 32.
Moreover, as explained in the second embodiment, if the core material of the fusion roller 32 and the pressure application roller 30 is iron, the thickness of the core is preferably set to 0.3 to 2.0 mm. In addition, more effects are obtained by setting the thickness of the elastic layer of the pressure application roller 30 by 0.25 to 0.8 times of the thickness of the elastic layer of the fusion roller 32.
In addition, with respect to the diameters of the fusion roller and the pressure application roller, the diameter of the fusion roller 32 and the diameter of the pressure application roller 30 are configured approximately the same in the present embodiments. However, the same effects are obtained as long as the diameter of the fusion roller 32 is in ±10% of the diameter of the pressure application roller 30.
In each of the above-described embodiments, the image forming device is explained as a color printer. However, it is not limited to this and may be a monochrome printer, a copy machine, a facsimile device, a multi function peripheral and the like that uses the electrographic method.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-017247 | Jan 2011 | JP | national |
