The present patent application claims priority pursuant to 35 U.S.C. §119 from Japanese Patent Application No. 2010-050501, filed on Mar. 8, 2010 in the Japan Patent Office, which is incorporated herein by reference in its entirety.
1. Field
Exemplary embodiments of the present disclosure relate to a fixing device and an image forming apparatus including the fixing device, and more specifically, a fixing device that fixes an image on a recording medium passing through a nip formed between a heat conductive member and a pressing member via an endless belt, and an image forming apparatus including the fixing device.
2. Description of the Background Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction apparatuses having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data. In such an image forming apparatus, for example, a charger uniformly charges a surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form an electrostatic latent image on the image carrier according to the image data; a development device supplies toner to the electrostatic latent image formed on the image carrier to make the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image carrier onto a recording medium or is indirectly transferred from the image carrier onto a recording medium via an intermediate transfer member; a cleaner then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium, thus forming the image on the recording medium.
For image forming apparatuses, different types of fixing devices are proposed. For example, a heat-roller type fixing device has a pressing roller and a fixing roller including a heat source. The pressing roller is pressed against the outer circumferential surface of the fixing roller to form a nip between them. In such a state, when a recording medium bearing an unfixed toner image passes through the nip, heat and pressure are applied to the recording medium at the nip to fix the toner image on the recording medium. In addition, a belt-type fixing roller is proposed to include an endless fixing belt extended between a heat roller and a fixing roller. From the outer surface of the fixing belt, the pressing roller is pressed against the fixing roller.
Furthermore, a fixing device is proposed to include a stationary member in sliding contact with the inner surface of a rotary member. For example, JP-H04-044075-A proposes a film-heating type fixing device, and JP-H10-213984-A proposes a pressing-belt type fixing device. However, a film-heating type fixing device like that described in JP-H04-044075-A has limitations in durability of a fixing belt and stability of the temperature of the fixing belt. For a pressing-belt type fixing device like that described in JP-H10-213984-A, a large heat capacity of fixing roller may increase the time required for raising the temperature of the fixing roller, thus increasing the warm-up time.
To deal with such a challenge, for example, JP-2007-334205-A proposes a fixing device including a fixing belt and a pipe-shaped heat conductive member. The heat conductive member is fixedly mounted within a loop formed by the fixing belt so as to be able to guide the circulation of the fixing belt. A heat source is disposed within the heat conductive member to heat the fixing belt via the heat conductive member.
Such a configuration can shorten the warm-up time of the fixing device. In addition, the pipe-shaped heat conductive member diffuses heat to uniformly heat the entire fixing belt, thus stabilizing the temperature of the entire fixing belt.
However, for the fixing device, since a plurality of halogen heaters is arranged side by side in contact with each other in the circumferential direction of the fixing belt, there is a dead angle at which a portion of radiation heat emitted from one halogen heater is blocked by the other halogen heater. In such a dead angle, a portion of the amount of heat from one halogen heater for heating the metal heat-conductive member is absorbed by the other halogen heater, thus preventing optimization of heating efficiency.
Further, detecting the temperature of the fixing belt in such a dead angle by a temperature detector (e.g., thermistor) is disadvantageous in terms of responsiveness and sensitivity. As a result, although the fixing device can shorten the warm-up time, the fixing belt might be overheated if, for example, continuous activation of the heater occurs due to a failure of the fixing device. In addition, for example, JP-2007-334205-A has no description of the relative positions of the temperature detector and a clearance between the fixing belt and the heat conductive member.
In an aspect of this disclosure, there is provided an improved fixing device including a cylindrically heat conductive member, a flexible fixing belt, a rotary pressing member, a plurality of heat sources, and a plurality of temperature detectors. The flexible fixing belt is looped for rotation around the heat conductive member. An inner circumference of the flexible fixing belt slidably contacts a portion of an outer circumferential surface of the heat conductive member. The rotary pressing member is disposed opposing the heat conductive member with the flexible fixing belt interposed therebetween, forming a nip between the fixing belt and the rotary pressing member. The plurality of heat sources is disposed in a circumferential direction of the fixing belt at a predetermined interval to heat the heat conductive member. The plurality of temperature detectors is provided corresponding to the plurality of heat sources to detect a surface temperature of the fixing belt at a detection position at which heating intensity of a corresponding one of the plurality of heat sources is not affected by any other one of the plurality of heat sources. In operation, the inner circumferential surface of the fixing belt contacts the heat conductive member at a position at which each of the plurality of temperature detectors contacts the fixing belt as the detection position or a position proximal to the detection position of each of the plurality of temperature detectors.
In an aspect of this disclosure, there is provided an improved image forming apparatus including the fixing device described above.
In an aspect of this disclosure, there is provided an improved fixing device including a cylindrical heat conductive member, a flexible fixing belt, a rotary pressing member, a plurality of heat sources, and a plurality of overheat prevention units. The flexible fixing belt is looped for rotation around the heat conductive member. An inner circumference of the flexible fixing belt slidably contacts a portion of an outer circumferential surface of the heat conductive member. The rotary pressing member is disposed opposing the heat conductive member with the flexible fixing belt interposed therebetween, forming a nip between the fixing belt and the rotary pressing member. The plurality of heat sources is disposed in a circumferential direction of the fixing belt at a predetermined interval to heat the heat conductive member. The plurality of overheat prevention units is provided corresponding to the plurality of heat sources to detect a surface temperature of the fixing belt at a detection position at which heating intensity of a corresponding one of the plurality of heat sources is not affected by any other one of the plurality of heat sources.
In an aspect of this disclosure, there is provided an improved image forming apparatus including the fixing device described above.
Additional aspects, features, and advantages of the present disclosure will be readily ascertained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The accompanying drawings are intended to depict exemplary embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.
In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results.
Although the exemplary embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the invention and all of the components or elements described in the exemplary embodiments of this disclosure are not necessarily indispensable to the present invention.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, exemplary embodiments of the present disclosure are described below with reference to
The image forming apparatus 100 includes an image forming section in which four image forming units are arranged side by side. Specifically, in the image forming section, four image forming units 101Y, 101C, 101M, and 101K that form toner images of yellow, cyan, magenta, and black, respectively, are arranged in this order from left to right in
In the image forming section, the image forming units 101Y, 101C, 101M, and 101K include photoconductors 21Y, 21C, 21M, and 21K of, for example, drum shape serving as latent image bearing members. The photoconductors 21Y, 21C, 21M, and 21K are surrounded by chargers; development devices 10Y, 10C, 10M, and 10K, and photoconductor cleaners. At an upper portion of the image forming apparatus 100 are disposed toner bottles 2Y, 2C, 2M, and 2M containing yellow, cyan, magenta, and black toners. From the toner bottles 2Y, 2C, 2M, and 2M, desired amounts of color toners are supplied to the development devices 10Y, 10C, 10M, and 10K through conveyance paths.
Below the image forming section is disposed an optical writing unit 9 serving as a latent-image forming unit. The optical writing unit 9 includes light sources, a polygon mirror, a f-θ lens, and reflection mirrors, and scans surfaces of the photoconductors 21Y, 21C, 21M, and 21K while emitting laser beams in accordance with image data.
Above the image forming section is an intermediate transfer belt 1 of, e.g., an endless belt shape serving as an intermediate transfer member. The intermediate transfer belt 1 is looped around a driving roller 1a and a driven roller 1b, and a driving motor serving as a driving source is connected to a rotation shaft of the driving roller 1a. When the driving motor is driven, the intermediate transfer belt 1 is rotated counterclockwise in
Further, a secondary transfer roller 4 serving as a secondary transfer device is disposed downstream from the primary transfer devices 11Y, 11C, 11M, and 11K in the rotation direction of the intermediate transfer belt 1. The driven roller 1b serving as a pressing member is disposed opposite the secondary transfer roller 4 with the intermediate transfer belt 1 interposed therebetween. The image forming apparatus 100 further includes a sheet tray 8, a sheet feed roller 7, and a pair of registration rollers 6. Moreover, the image forming apparatus 100 includes a fixing device 5 to fix an image on a recording sheet S (e.g., a sheet of paper or a transfer material) and a pair of discharge rollers 3 to discharge the recording sheet S. The fixing device 5 and the pair of discharge rollers 3 are disposed downstream from the secondary transfer roller 4 in a transport direction of the recording sheet S.
Next, operation of the image forming apparatus 100 is described below. In the image forming units 101Y, 101C, 101M, and 101K, when the photoconductors 21Y, 21C, 21M, and 21K start to rotate, corresponding uniformly chargers charge the surfaces of the photoconductors 21Y, 21C, 21M, and 21K. The optical writing unit 9 emits laser beams onto the photoconductors 21Y, 21C, 21M, and 21K in accordance with image data to form electrostatic latent images on the photoconductors 21Y, 21C, 21M, and 21K. The development devices 10Y, 10C, 10M, and 10K supply toners to the photoconductors 21Y, 21C, 21M, and 21K to develop the latent images into visible toner images. Thus, single color images of yellow, cyan, magenta, and black are formed on the photoconductors 21Y, 21C, 21M, and 21K, respectively. When the driving roller 1a is rotated by the driving motor, the driven roller 1b and the secondary transfer roller 4 are rotated by the rotation of the driving roller 1a. As a result, the intermediate transfer belt 1 is rotated to transfer the respective visible toner images onto the intermediate transfer belt 1 at the primary transfer devices 11Y, 11C, 11M, and 11K. Thus, a composite color image is formed on the intermediate transfer belt 1. After the transfer process, the photoconductor cleaners remove residue toner particles remaining on the surfaces of the photoconductors 21Y, 21C, 21M, and 21K in preparation for the following image formation.
Meanwhile, the sheet feed roller 7 picks and feeds the recording sheet S from the sheet tray 8 to the pair of registration rollers 6. In synchronous with the above-described image formation, the pair of registration rollers 6 feeds the recording sheet S to a secondary transfer nip formed by the secondary transfer roller 4 and the intermediate transfer belt 1. The intermediate transfer belt 1 and the secondary transfer roller 4 sandwich the recording sheet S at the secondary transfer nip, and the composite toner image on the intermediate transfer belt 1 are transferred onto the recording sheet S by the secondary transfer roller 4.
After the secondary transfer process, the recording sheet S is transported to the fixing device 5 and sandwiched at a fixing nip formed by heating members (for example, a fixing belt 30 and a heat conductive member 31) and a rotary pressing member (pressing roller 40). At the fixing nip, heat and pressure are applied to the composite toner image on the recording sheet S. Thus, the toner image is fixed on the recording sheet S. The recording sheet S is discharged from the fixing nip and further from the pair of discharge rollers 3 to the exterior of the image forming apparatus 1. Meanwhile, after the secondary transfer process, an intermediate-transfer-member cleaner 12 removes residue toner particles remaining on the intermediate transfer belt 1 in preparation for the following image formation.
In this exemplary embodiment, the fixing device 5 includes an endless fixing belt (the fixing belt 30), a metal heat conductor (the heat conductive member 31) in sliding contact with a portion of an inner circumferential surface of the endless fixing belt, a heat source unit (a halogen heater unit 34) to heat the metal heat conductor, and a rotary pressing member (the pressing roller 40). The fixing device 5 also includes a plurality of heat sources (halogen heaters 34a and 34b) as the heat source unit and a plurality of temperature detectors (thermistors 35a and 35b) corresponding to the heat sources. The heat sources are arranged side by side in the circumferential direction of the fixing belt at a certain interval. Each of the temperature detectors is disposed at a position at which detection of the heating intensity of a corresponding one of the heat sources is not distorted by the other heat source. During rotation, the inner circumferential surface of the fixing belt contacts the metal heat conductor at a position at which each of the temperature detectors contacts the fixing belt or at a position of the fixing belt proximal to the detection position of each of the temperature detectors. The term “circumferential direction” used herein represents a rotation direction of the fixing belt or the pressing roller, and the term “axial direction” used herein represents a direction perpendicular to the rotation direction of the fixing belt or the pressing roller.
Next, a basic configuration of the fixing device 5 is described with reference to
The fixing device 5 includes, as heating members, the fixing belt 30 and the heat conductive member 31 in proximity to the inner circumferential surface of the fixing belt 30. Within the heat conductive member 31 is disposed the halogen heater unit 34 serving as a heat source to heat the heat conductive member 31. The fixing device 5 further includes the pressing roller 40 serving as a rotary pressing member. It is to be noted that the heat source is not limited to a halogen heater and may be, for example, an infrared heater or a heat resistant member.
The fixing belt 30 is guided by the heat conductive member 31 over an area other than the fixing nip, and disposed so as to have a certain clearance of 1 mm or smaller between the heat conductive member 31 and it at a stationary state of the heat conductive member 31. Within the loop formed by the fixing belt 30, a nip formation member 32 is supported by the heat conductive member 31 so as to slide indirectly over the inner circumferential surface of the fixing belt 30 with a lubricant sheet 37 of, e.g., a mesh type interposed therebetween. Alternatively, the nip formation member 32 may directly contact the inner circumferential surface of the fixing belt 30. Further, as illustrated in
In
The pressing roller 40 includes a hollow metal roller having a silicon rubber layer and a surface releasing layer of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) or polytetrafluoroethylene (PTFE) to obtain a good releasing performance. The pressing roller 40 is rotated in a direction indicated by an arrow R in
Further, a spring or other urging member urges the pressing roller 40 toward the fixing belt 30. As a result, the silicon rubber layer of the pressing roller 40 is compressed and deformed to form a certain width of the fixing nip N. It is to be noted that the pressing roller 40 may be formed of a solid roller. However, a hollow roller is preferable in that the heat capacity is relatively small. The pressing roller 40 may include a heat source such as a halogen heater.
The silicone rubber layer of the pressing roller 40 may be solid rubber. Alternatively, if a heat source, such as a heater, is not provided in the pressing roller 40, the silicone rubber layer may be, e.g., sponge rubber. Sponge rubber is preferable in that the insulation performance is relatively high and thus less of the heat of the fixing belt 21 is absorbed by the pressing roller 40.
The fixing belt 30 is a metal belt including nickel, SUS (stainless steel), and/or other metal or a resin belt including polyimide and/or other resin. The fixing belt 30 has a surface releasing layer of, e.g., PFA or PTFE to prevent toner on the recording sheet S from adhering to the fixing belt 30. The fixing belt 30 may include an elastic layer of, e.g., silicone rubber between a base member and the surface releasing layer of, e.g., PFA or PTFE. If the fixing belt 30 does not include the elastic layer, the heat capacity of the fixing belt 30 is relatively small, thus enhancing the fixing performance. However, when an unfixed toner image is compressed by the surface of fixing belt 30, minute irregularity of the surface of the fixing belt 30 may be transferred on the toner image, causing minute irregularity (e.g., orange-peel-like asperity) on a solid portion of the toner image. To prevent such irregularity, it is preferable that the silicone rubber layer has a thickness of, e.g., 100 um or more. For such a configuration, deformation of the silicone rubber layer can absorb minute irregularity of the surface of the fixing belt 30, thus preventing the minute irregularity from being transferred onto the resultant toner image.
The heat conductive member 31 has a hollow pipe shape and includes aluminum, iron, stainless steel, and/or other metal. Unlike the pressing roller 40, the heat conductive member 31 is fixed so as not to rotate. In
Moreover, within the heat conductive member 31 may be disposed a support member 33 to support the fixing nip N. For such a configuration, in a case in which the support member 33 is heated by, e.g., radiation heat of the halogen heater unit 34, the surface of the support member 33 may be thermally insulated or mirror-finished to block heat from the halogen heater unit 34, thus preventing wasteful heat energy consumption. In an example embodiment, the support member has a bottom face 33c, two side faces 33b, 33a and a space S between the two side faces, as shown for example in
As a heat source for heating the heat conductive member 31, the fixing device 50 includes a plurality of halogen heaters in the halogen heater unit 34 and controls turning on-and-off of the halogen heaters independently of each other in accordance with the size of a recording sheet.
When the pressing roller 40 is rotated by the drive source, the drive force of the pressing roller 40 is transmitted to the fixing belt 30 at the fixing nip N to rotate the fixing belt 30. At the fixing nip N, the fixing belt 30 is sandwiched with the pressing roller 40 and the nip formation member 32 (via the lubricant sheet 37) to rotate. Meanwhile, over an area other than the fixing nip N, the fixing belt 30 is guided by the heat conductive member 31 so as not to move away from the heat conductive member 31 beyond a certain distance. In
The fixing device 50 also includes a controller to separately control the halogen heaters of the halogen heater unit 34 in accordance with detection results of the thermistors 35 serving as temperature detectors to control the surface temperature of the heat conductive member 31.
Such a configuration can shorten the warm-up time of the fixing device at a reduced cost and allows the heat conductive member 31 to e and transfer heat to the entire fixing belt 30 in a uniform manner. Thus, the fixing device 50 can stabilize the temperature of the entire fixing belt 30.
As described above, the fixing device 50 includes a plurality of halogen heaters serving as heat sources. In the following example, the fixing device 50 includes two halogen heaters 34a and 34b. However, it is to be noted that the number of halogen heaters in the fixing device 50 is not limited to two and may be any other suitable number.
For example, assuming that a single halogen heater is used to heat the fixing belt 30, when a recording sheet of a small width, such as a small-size sheet of paper, passes through the fixing nip N, heat of the fixing belt 30 is not absorbed by the recording sheet in an non-sheet-pass area thereof over which the recording sheet does not pass. Consequently, the surface temperature of the fixing belt 30 increases excessively. By contrast, for example, a first halogen heater having a light flux distribution toward an axial middle portion of the fixing belt 30 and a second halogen heater having a light flux distribution toward an axial end portion of the fixing belt 21 may be arranged side by side in a circumferential direction of the fixing belt 30. Controlling the halogen heaters thus arranged allows optimal temperature control in accordance with the width of a recording medium passing through the nip.
However, even in a case in the fixing device includes two halogen heaters, if the halogen heaters 34a and 34b are arranged in contact with each other in the circumferential direction, one of the heaters blocks radiation heat of the other an a greater angle, resulting in an increased dead angle.
Specifically, as illustrated in
Hence, as illustrated in
Accordingly, the range in which the heat conductive member 31 receives radiation heat from the halogen heaters 34a and 34b is indicated by a shaded area in
In this configuration, if the thermistors 35 serving as temperature detectors corresponding to the halogen heaters 34a and 34b are disposed at the same position in the circumferential direction of the fixing belt 30, one of the halogen heaters 34a and 34b may prevent one of the thermistors 35 from obtaining a desired detection condition. That is, if one of the thermistors 35 is disposed within the range, as indicated by the shaded area in
Hence, as illustrated in
For this exemplary embodiment, the interval between the halogen heaters 34a and 34b (i.e., the distance between the axial centers of the halogen heaters 34a and 34b) is, for example, 10 mm. The interval between the plurality of heat sources and the positions of the temperature detectors corresponding to the heat sources are optimally determined in accordance with, e.g., the shapes, sizes, and materials of the fixing belt 30 and the heat conductive member 31 and the amount of heat of the heat sources.
In
Next, the clearance between the fixing belt 30 and the heat conductive member 31 is described. As described above, the fixing belt 30 is guided by the heat conductive member 31 over an area other than the fixing nip N. The fixing belt 30 and the heat conductive member 31 have a certain clearance therebetween of, for example, 1 mm or smaller. Since the fixing belt 30 is not taut, the track of the fixing belt 30 is different between the rotational state and the stopped state.
As illustrated in
As illustrated in
As described above, a clearance between the fixing belt 30 and the heat conductive member 31 creates a difference between the surface temperature of the fixing belt 30 detected by the thermistor unit 35 and the surface temperature of the heat conductive member 31. In particular, if the thermistor unit 35 is disposed at a position at which the clearance between the fixing belt 30 and the heat conductive member 31 appears during rotation of the fixing belt 30 in, e.g., image formation, the above-described temperature difference prevents accurate detection of the temperature of the fixing belt 30. Consequently, electric power may be wasted, or the heat conductive member 31 might become overheated. If the thermistor unit 35 is disposed at a position at which contact and separation of the fixing belt 30 with and from the heat conductive member 31 are repeated, unexpected overheating of the fixing belt 30 might occur. In particular, such overheating might occur in the fixing device capable of rapidly raising the temperature.
Hence, ordinarily it is necessary that the thermistor unit 35 is disposed at a position at which, during rotation, the fixing belt 30 comes into contact with the heat conductive member 31. It is also preferable that the thermistor unit 35 be disposed at a position at which, when the fixing belt 30 is stopped, the fixing belt 30 contacts the heat conductive member 31. However, when stopped, the fixing belt 30 is stationary and the clearance between the fixing belt 30 and the heat conductive member 31 is maintained constant. Further, by observing the stationary state, the clearance and temperature difference between the fixing belt and the heat conductive member 31 can be determined and defined in advance. The rapid temperature-rising capability of the fixing device allows the setting temperature in the rotation period of the fixing belt to be set to a relatively low temperature or the heater turned off. Accordingly, the thermistor unit 35 need not necessarily be disposed at the position at which the fixing belt 30 contacts the heat conductive member 31 when the fixing belt 30 is stopped.
It is preferable that a support member 33 is provided within the heat conductive member 31 to support the fixing nip N. Such a configuration can enhance the accuracy with which the nip formation member 32 is positioned. As illustrated in
In a case in which the support member 33 is heated by radiation heat of the halogen heater unit 34, In such a case, the surface of the support member 33 may be insulated or mirror-finished to prevent heat absorption by the support member 33. Such a configuration can prevent wasteful heat energy consumption. Further, in addition to an appropriate surface treatment, the shape of the support member 33 may be modified as well.
For example, in accordance with the position and shape of the halogen heater unit 34, the shape of the support member 33 having such a mirror-finished surface may be modified as illustrated in
Forming the support member 33 in the shape illustrated in
In addition, in the case in which the support member 33 has the shape illustrated in
In the configuration illustrated in
In
As described above, for the fixing device according to this exemplary embodiment, one of the plurality of halogen heaters serving as heat sources is disposed at a position so as not to block heat from the other. Such a configuration can shorten the warm-up time and effectively diffuse heat from the heat conductive member 31 to uniformly heat the entire fixing belt. Accordingly, the fixing device can stabilize the temperature of the entire fixing belt with a simple configuration, thus resulting in cost reduction.
In the fixing device, the temperature detectors are disposed at positions suitable in response and/or sensitivity so that the temperature detectors are most sensitive and heat-intensive for the corresponding halogen heaters, and the temperature detection of the temperature detectors is not affected by the clearance between the fixing belt and the heat conductive member. Such a configuration can promptly and accurately detect a change in the temperature of the heating member caused by, for example, sheet passing through the nip, and accurately and stably control the temperature of the fixing nip N.
Alternatively, instead of or in addition to the temperature detectors, the fixing device may include overheat prevention units 38, such as thermostats.
In the fixing device, the overheat prevention units 38 may be disposed at the same positions as those of the above-described temperature detectors. For example, the thermostats 38a and 38b corresponding to the halogen heaters 34a and 34b, respectively, may be disposed at positions illustrated in
Since the fixing device is energy-saving and warms up quickly, the fixing belt need not be heated during standby time. Accordingly, normally, in non-sheet passing period (the stopped state of the fixing belt), the temperature detectors and the halogen heaters may be turned off. By contrast, the overheat prevention units needs to monitor the fixing belt irrespective of rotational or stopped states because, even in the stopped state, the fixing belt may run out of control due to, e.g., a short circuit in electric circuits.
It is preferable that the overheat prevention units 38a and 38b are disposed at positions so that the fixing belt 30 contacts with the heat conductive member 31 in a stopped state as well as during rotation. However, in a stopped state, the fixing belt 30 is stationary and the clearance between the fixing belt 30 and the heat conductive member 31 is maintained substantially constant. Further, if the clearance is small enough for the fixing device to be able to control it, it does not matter that the fixing device has the clearance between the fixing belt 30 and the heat conductive member 31 in a stopped state.
In
It is to be noted that the values shown in
Since the fixing device according to this exemplary embodiment can raise the temperature quickly, it is preferable that the thermostats can accurately response at high speed. The above-described configuration can provide such overheat prevention units capable of controlling at high speed and accuracy.
By using the fixing device 5 having the above-described configuration in the image forming apparatus 100, the image forming apparatus 100 can function as described above.
Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.
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2010-050501 | Mar 2010 | JP | national |
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