JP2016153877A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that uses a plurality of heat sources having different heat distributions (light distributions), and improve heating efficiency compared to a prior art to reduce first print time and provide good fixability.SOLUTION: A fixing device 200 comprises a rotatable fixing member 201 and a rotatable pressure member 203, and includes a plurality of heat sources 202A and 202B heating the fixing member, a nip forming member 206 forming a nip part N with the pressure member with the fixing member therebetween, and a support member 207 supporting the nip forming member, which are arranged inside the fixing member, the fixing device fixing a toner image on a recording material at the nip part. The plurality of heat sources 202A and 202B each include heat distribution parts 202c and 202d having different distributions in the longitudinal direction, and are arranged in separate areas 211 and 212 across the support member 207; the heat source 202A having a larger heat quantity is arranged in the larger area 211 of said areas, and the heat source 202B having a smaller heat quantity is arranged in the smaller area 212 of said areas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device used in an electrostatic recording type image forming apparatus such as a copying machine, a facsimile machine, or a printer, more specifically, a nip portion is formed between an endless fixing member and a pressure member. The present invention relates to a fixing device that performs a fixing process on a recording material passing through a section. The present invention also relates to an image forming apparatus equipped with the fixing device.

In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimiles.
In an image forming apparatus, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. Formed on recording material. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  As an example of such a fixing device, a belt-type fixing device (for example, Patent Document 1) and a surf fixing (film fixing) fixing device (for example, Patent Document 2) using a ceramic heater are known.

  In recent years, with belt type fixing devices, further warm-up time (time required from room temperature to a predetermined printable temperature (reload temperature) such as when the power is turned on) and first print time (after receiving a print request, It is desired to shorten the time required for the printing operation after the print preparation and the paper discharge to be completed (Problem 1). In addition, as the speed of image forming apparatuses increases, the number of sheets to be passed per unit time increases and the required amount of heat increases, so that there is a problem that the amount of heat is insufficient (so-called temperature drop), particularly at the beginning of continuous printing. (Problem 2).

  As a method for solving the problem of the problem 1, surf fixing using a ceramic heater has been proposed. With this method, the heat capacity and size can be reduced compared to the belt type fixing device. However, since only the nip part is locally heated, the other parts are not heated, and the belt is cooled most at the entrance of the nip part. There is a problem that fixing failure tends to occur. In particular, in a high-speed machine, there is a problem that fixing failure is more likely to occur because the belt rotates fast and the heat radiation of the belt outside the nip increases (problem 3).

  In order to solve the problems 1 to 3, even if the endless belt can be warmed, the first print time can be shortened, and the shortage of heat at the time of high-speed rotation can be eliminated, so that it can be mounted on a high-production image forming apparatus. A fixing device capable of obtaining good fixing properties has been proposed (Patent Document 3).

  In the fixing device shown in FIG. 1 of Patent Document 3, a pipe-shaped metal heat conductor 2 is fixed inside the endless belt 1 so as to be able to guide the movement of the endless belt 1. The endless belt 1 is heated by the heat source 3 through the metal heat conductor 2. Further, a pressure roller 4 that forms a nip portion N in contact with the metal heat conductor 2 via the endless belt 1 is provided, and the endless belt 1 is moved in the circumferential direction so as to rotate as the pressure roller 4 rotates. Let With this configuration, it is possible to warm the entire endless belt constituting the fixing device, to shorten the first print time from the heating standby time, and to solve the shortage of heat during high-speed rotation. Yes.

  However, in order to further save energy and improve the first print time, it is necessary to further improve the thermal efficiency. From the configuration in which the endless belt is indirectly heated through the metal heat conductor, the metal heat conductor is not used. A configuration for directly heating the endless belt has been devised. With this configuration, the heat transfer efficiency can be greatly improved to reduce power consumption, and the first print time can be further shortened. In addition, the cost can be reduced because there is no metal heat conductor.

  By the way, in such a fixing device, a plurality of halogen heaters having different heat distributions (light distributions) are generally used in order to fix a toner image on a recording material of each size. For example, the fixing device includes a heater having a heat distribution corresponding to the A4 vertical paper width (210 mm) and a heater having a heat distribution between the A4 vertical paper width and the A3 vertical paper width (210 mm to 297 mm).

  On the other hand, with the downsizing of the fixing device, the diameter of the endless belt is reduced, and the distance between the halogen heaters in the cross section of the fixing device is shortened. For example, when two halogen heaters having different heat distributions are used in parallel, the radiant heat of one halogen heater heats the other halogen heater, resulting in a decrease in radiation efficiency.

  Therefore, by arranging a plurality of halogen heaters on both sides of the reflecting member, the fixing device can efficiently heat the heating roller and shorten the warm-up time without the plurality of halogen heaters heating each other. Has been proposed (Patent Document 4). However, there is a demand for further improvement in heating efficiency.

  Therefore, in the present invention, in a fixing device using a plurality of heat sources having different heat distributions (light distributions), the heating efficiency is further improved as compared with the conventional one, and the first print time is shortened and good fixability is obtained. Is an issue.

  In order to solve this problem, a rotatable fixing member, a pressure member that is rotatably disposed opposite to the fixing member, and includes a plurality of heat sources that heat the fixing member inside the fixing member; A nip forming member that forms a nip portion with the pressure member via a fixing member and a support member that supports the nip forming member are arranged to fix the toner image on the recording material at the nip portion. In the fixing device, each of the plurality of heat sources has a heat distribution portion having a different distribution in a longitudinal direction, and is disposed in a separate region sandwiching the support member. Among the plurality of heat sources, A fixing device is proposed, which is arranged in a wide area of the area, and a heat source with a small amount of heat generation is arranged in a narrow area of the area.

  Even when a plurality of heat sources having different heat distribution patterns are used, the radiation heat of one halogen heater heats the other halogen heater, and the efficiency of radiation does not decrease. A further improvement in heating efficiency can be realized as compared with the case where a plurality of heat sources are simply disposed with the support member interposed therebetween.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a fixing device according to a first embodiment. It is a schematic sectional drawing which shows an example of the fixing device of a conventional structure. FIG. 3 is a schematic perspective view of the inside of a fixing belt of the fixing device of FIG. 2. It is a schematic perspective view when FIG. 4 is turned upside down. FIG. 6 is a schematic perspective view of the inside of a fixing belt of a fixing device according to a second embodiment. It is a schematic perspective view when FIG. 6 is turned upside down. It is a schematic sectional drawing in the apparatus edge part of FIG. It is a schematic sectional drawing in the apparatus center part of FIG. FIG. 10 is a schematic cross-sectional view at both ends of a fixing device according to a third embodiment. It is a schematic block diagram of the fixing device concerning 4th Embodiment.

The configuration of the image forming apparatus according to the embodiment of the present invention will be described below with reference to FIG.
An image forming apparatus 100 shown in FIG. 1 is a tandem type color printer in which image forming units for forming a plurality of color images are juxtaposed along a belt extending direction. However, the present invention is not limited to this method, and can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

  The image forming apparatus 100 includes photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers that can form images as images corresponding to colors separated into yellow, cyan, magenta, and black, respectively. The tandem structure is adopted.

  In the image forming apparatus 100, an intermediate transfer member (hereinafter referred to as an endless belt) in which a visible image formed on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk can move in the direction of arrow A1 while facing the respective photosensitive drums. (Referred to as a transfer belt) 11. By executing the primary transfer process, the images of the respective colors are superimposed and transferred, and then transferred to the recording material S on which the recording sheet or the like is used by performing a secondary transfer process.

  Around each photosensitive drum, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum. The photosensitive drum 20Bk that performs black image formation will be described as a representative. A charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotation direction of the photosensitive drum 20Bk are arranged. ing. The optical writing device 8 is used for writing using the writing light Lb performed after charging.

  In the superimposing transfer on the transfer belt 11, the visible image formed on each of the photosensitive drums 20 </ b> Y, 20 </ b> C, 20 </ b> M, and 20 </ b> Bk is transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. Is done. For this reason, the transfer is performed in the A1 direction by applying a voltage from the primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed opposite to the photosensitive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween. The timing is shifted from the upstream side toward the downstream side.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images, respectively.

  The image forming apparatus 100 is disposed so as to face four image stations that perform image forming processing for each color and above each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and includes a transfer belt 11 and a primary transfer roller 12Y. , 12C, 12M, and 12Bk, a secondary transfer roller 5 that is arranged to face the transfer belt 11 and is driven by the transfer belt 11, and is arranged to face the transfer belt 11. A belt cleaning device 13 is provided for cleaning the transfer belt 11, and an optical writing device 8 is provided oppositely below these four image stations.

  The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. The optical writing device 8 emits writing light Lb corresponding to each color to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk to form an electrostatic latent image on the photosensitive drums 20Y, 20C, 20M, and 20Bk. It is configured as follows. In FIG. 1, for the sake of convenience, the writing light Lb is labeled only for the image station of the black image, but the same applies to the other image stations.

  The image forming apparatus 100 is provided with a sheet feeding device 61 as a paper feeding cassette on which recording materials S conveyed between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11 are stacked. Yes. Further, the recording material S conveyed from the sheet feeding device 61 is directed toward the transfer portion between each photosensitive drum and the transfer belt 11 at a predetermined timing in accordance with the toner image formation timing by the image station. A pair of registration rollers 4 is provided. In addition, a sensor that detects that the leading edge of the recording material S has reached the registration roller pair 4 is provided.

  Further, the image forming apparatus 100 includes a fixing device 200 as a roller fixing type fixing unit for fixing the toner image to the recording material S to which the toner image is transferred, and the recording material S that has been fixed. A discharge roller 7 is provided for discharging to the outside of the main body. In addition, a discharge tray 17 on which the recording material S discharged to the outside of the main body of the image forming apparatus 100 by the discharge roller 7 is stacked is provided on the upper part of the main body of the image forming apparatus 100. Further, toner bottles 9Y, 9C, 9M, and 9Bk filled with yellow, cyan, magenta, and black toners are provided below the paper discharge tray 17.

  The transfer belt unit 10 includes a drive roller 72 and a driven roller 73 around which the transfer belt 11 is wound, in addition to the transfer belt 11 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk.

  The driven roller 73 also has a function as a tension urging unit for the transfer belt 11. For this reason, the driven roller 73 is provided with an urging unit using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13 constitute a transfer device 71.

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 100, and has a feeding roller 3 that contacts the upper surface of the uppermost recording material S. The uppermost recording material S is fed toward the registration roller pair 4 by driving the feeding roller 3 counterclockwise in the drawing.

  Although not shown in detail, the cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 11. The cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign matters such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade.

  The cleaning device 13 also has discharge means for carrying out and discarding the residual toner removed from the transfer belt 11.

FIG. 2 is a schematic configuration diagram illustrating the fixing device according to the first embodiment.
The fixing device 200 includes a fixing belt 201 as a rotatable fixing member and a pressure roller 203 as a pressure member that is disposed opposite to the fixing belt 201 and can rotate. Thus, the fixing belt 201 is directly heated by radiant heat from the inner peripheral side. At this time, in the fixing belt 201 of FIG. 2, there is a nip forming member 206 that forms a nip portion with the pressure roller 203 via the fixing belt 201, and directly on the inner surface of the fixing belt or through a sliding sheet. It is designed to slide indirectly. The recording material S that has passed through the secondary transfer roller 5 is conveyed in the direction of the arrow in FIG. 2, and the toner image on the recording material S is fixed by heating and pressing at the nip portion.

  Although the shape of the nip portion is flat in FIG. 2, it may be a concave shape or other shapes. In the case of the concave nip portion, the discharge direction of the leading end of the recording material is closer to the pressure roller, and the separation is improved, so that the occurrence of jam is suppressed.

  The fixing belt 201 is composed of a metal belt such as nickel or SUS or an endless belt or film using a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. There may be an elastic layer formed of a silicone rubber layer or the like between the belt substrate and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and the image has a crusty skin shape. There may be a problem that the gloss unevenness (skin skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  A stay 207 as a support member for supporting the nip forming member 206 and the nip portion N is provided inside the fixing belt 201 to prevent the nip forming member 206 that receives pressure from the pressure roller 203 from being bent in the axial direction. A uniform nip width is obtained. The stay 207 is held and fixed and positioned at flanges as holding members at both ends. In addition, a reflection member 209 is provided between the halogen heater 202 and the stay 207, and wasteful energy consumption due to the stay 207 being heated by radiation heat from the halogen heater 202 or the like is suppressed. Here, instead of providing the reflecting member 209, the same effect can be obtained even if the surface of the stay 207 is heat-insulated or mirror-finished.

  The pressure roller 203 has an elastic rubber layer 204 on a metal core 205, and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain releasability. The pressure roller 203 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 203 is pressed against the fixing belt 201 by a spring or the like, and has a predetermined nip width when the elastic rubber layer 204 is crushed and deformed. The pressure roller 203 may be a hollow roller, and the pressure roller 203 may have a heating source such as a halogen heater. The elastic rubber layer 204 may be solid rubber, but if there is no heater inside the pressure roller 203, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt to lose heat.

  The fixing belt 201 rotates along with the pressure roller 203. In the case of FIG. 2, the pressure roller 203 is rotated by a driving source, and the driving force is transmitted to the belt at the nip portion N, whereby the fixing belt 201 is rotated. The fixing belt 201 is sandwiched and rotated at the nip portion N, and travels while being guided by the flange 208 at both ends other than the nip portion.

  With the above configuration, it is possible to realize a fixing device that is inexpensive and has a fast warm-up.

Here, a conventional fixing device will be described.
Conventionally, a fixing device having three halogen heaters (for example, FIG. 26 of Patent Document 5) and a fixing device having two halogen heaters (for example, FIGS. 2 and 3 of Patent Document 5) are known. In the former, since the three heaters are collectively arranged inside the stay, the glass tubes are heated when the heaters are turned on, and the heating efficiency is reduced by the amount that the radiant heat does not directly hit the fixing belt. Furthermore, since the three heaters are surrounded by the reflecting member, the heating efficiency is reduced by the attenuation of radiation due to reflection and the narrowed irradiation angle.

In the latter, since the two heaters are collectively arranged on the lower side of the stay, the glass tubes are heated when the heaters are turned on, and the heating efficiency is reduced by the amount that the radiant heat does not directly hit the fixing belt.
FIG. 3 is a schematic cross-sectional view of a fixing device having two halogen heaters. Such a fixing device is known from Patent Document 6, for example. Since the two halogen heaters 202 are surrounded by the reflecting member, the heating efficiency is lowered by the attenuation of radiation due to reflection and the narrowing of the irradiation angle as shown by the bidirectional arrows. Here, the irradiation angle is an angle at which the radiation from the halogen heater 202 directly hits the fixing belt 201. For example, one of the halogen heaters 202 is a central heater that heats the longitudinal center of the fixing belt, and the other is an end heater that heats the longitudinal end of the fixing belt.

  Another fixing device having two halogen heaters is known from Patent Document 4, for example. The fixing device 7 includes a fixing belt 21, a fixing heater 23, a pressure roller 25, and a reflector 27. The reflector 27 includes a support portion 27 a arranged substantially vertically, a contact portion 27 b that contacts the pressure roller 25 with the fixing belt 21 interposed therebetween, and a time period for irradiation of radiation light from the fixing heater 23 to the fixing belt 21. And an irradiation restricting portion 27b for varying in the width direction. The region in the fixing belt 21 is equally divided by the reflector 27 and the two fixing heaters 23 are divided and arranged on the left and right sides of the reflector 27, so that the glass tubes are not heated when the heater is turned on. Efficiency does not decrease. Further, since the two fixing heaters 23 are equally divided and arranged in the same size region, the irradiation angle at which the radiation from the heater directly hits the fixing belt 21 is also the same on the left and right. However, there is room for improvement in terms of improving heating efficiency.

Therefore, in the present invention, the fixing device is configured as follows.
Referring to FIG. 2, the stay 207 includes a first member 207A and a second member 207B each having a substantially L-shaped cross section. The first member 207A has a first partition portion 207c for partitioning the two halogen heaters 202A and 202B, and a first fixing portion 207d for fixing the nip forming member 206. The second member 207B has a second partition part 207e for partitioning the two halogen heaters 202A and 202B, and a second fixing part 207f for fixing the nip forming member 206. The first partition portion 207c and the second partition portion 207e have substantially the same length throughout the longitudinal direction (the direction perpendicular to the paper surface), but the first fixing portion 207d is longer than the second fixing portion 207f. The first partition part 207c and the second partition part 207e extend linearly in the longitudinal direction of the heater. Therefore, the first partition portion 207c and the second partition portion 207e come into contact with each other, so that the stay 207 has a substantially T-shaped cross section. However, in the fixing belt 201, the first region 211 is larger than the second region 212. Widened (Fig. 4).

  Therefore, by arranging the two halogen heaters 202A and 202B in the upper and lower separate regions with the stay 207 interposed therebetween, the glass tubes are not heated when the heaters are turned on, so that the heating efficiency is not lowered. Further, the halogen heater 202A having a large amount of heat and power is arranged in the wide first region 211 in the fixing belt 201, and the halogen heater 202B having a small amount of heat and power is arranged in the narrow second region 212 in the fixing belt 201. doing. As compared with the fixing device in which the region in the fixing belt is evenly divided, the heating efficiency is improved by the amount of irradiation angle α of the halogen heater 202A that generates a large amount of heat and electric power. On the other hand, the heating efficiency is lowered by the amount of the irradiation angle β of the halogen heater 202B that generates less heat and less power. As a result, the heating efficiency of the entire fixing device 200 is improved as compared with the fixing device in which the area in the fixing belt is equally divided. Since the region where the heat source with a small amount of heat is arranged becomes narrow, the thermal efficiency is lowered as the irradiation angle of the radiant heat hitting the fixing member from the heat source with a small amount of heat is reduced, but the thermal efficiency as the fixing device is improved.

  In other words, since radiation from the two halogen heaters 202A and 202B arranged with the stay 207 interposed therebetween is blocked by the stay 207, a portion on which the radiation strikes and a portion on which the radiation does not strike are generated on the fixing belt 201, respectively. . In that case, the part where the radiation from the halogen heater 202A placed in the wide first area 211 hits the fixing belt becomes larger, and the part where the radiation from the halogen heater 202B placed in the narrow second area 212 hits the fixing belt becomes more. Get smaller. Therefore, by placing the heater with the larger amount of heat generation and electric power in a wide area, the heating efficiency of the entire fixing device using two halogen heaters increases. In addition to the stay, there may be a device configuration in which an additional member that blocks radiation from the heater is present between the heater inside the fixing belt and the fixing belt. Since the heating efficiency can be increased in consideration of the area to be obtained, the degree of freedom in designing the shape and arrangement of the additional members inside the fixing belt can be increased accordingly.

  Note that the shape of the fixing belt 201 may change depending on the operation state of the apparatus, for example, when rotating or not rotating, but the above-described effects can be obtained if the configuration of the present invention is satisfied at least when the heater is turned on. . In other words, the plurality of heaters have different heat distribution portions with different distributions in the longitudinal direction, and are arranged in different regions sandwiching the stay, and a heater having a large amount of heat generation among the plurality of heaters is a wide region of the region. The heater with a small calorific value only needs to be arranged in a narrow region among the regions.

4 is a schematic perspective view of the inside of the fixing belt of the fixing device of FIG. 2, and FIG. 5 is a schematic perspective view when FIG. 4 is turned upside down.
In particular, as shown in FIG. 4, the halogen heater 202 </ b> A disposed in the first region 211 is a central heater that heats the longitudinal central portion of the fixing belt 201, and the heat distribution portion 202 c that is heated when energized is disposed in the longitudinal central portion. Have. In particular, as shown in FIG. 5, the halogen heater 202 </ b> B disposed in the second region 212 is an end heater that heats the longitudinal end of the fixing belt 201, and the heat distribution unit 202 d that is heated when energized is disposed at the longitudinal end. Have in part. Portions other than the heat distribution units 202c and 202d (non-heat distribution units) are not heated when energized. The halogen heaters 202A and 202B have heat distribution portions with different distributions in the longitudinal direction, and the heat distribution portions 202c and 202d are arranged so as not to overlap in the longitudinal direction. A reflection member 209 is provided between the heat distribution portions 202c and 202d of the halogen heaters 202A and 202B and the stay 207.

  For example, the heat distribution unit 202c has a length of 217 mm, the halogen heater 202A has a power amount of 770 W, the heat distribution unit 202d has a length of 63 mm (126 mm in total), and the halogen heater 202B has a power of 440 W. Have quantity. Therefore, when printing A4 landscape or A3 portrait (297 mm), it is necessary to turn on both the halogen heater 202A and the halogen heater 202B.

  Thus, the calorific value and electric energy of the central heater are larger than the calorific value and electric energy of the end heater. However, both the amount of heat generated and the amount of power per unit length of the halogen heaters 202A and 202B are, for example, 3.5 W / mm. This is to keep the amount of heat applied to the toner and the recording material constant in order to keep the toner fixing property on the recording material and the glossiness of the image constant.

  Here, the total heating efficiency is improved by widening the irradiation angle of the halogen heater 202A having the wide heat distribution section 202c rather than widening the irradiation angle of the halogen heater 202B having the narrow heat distribution section 202d. In other words, in the cross section orthogonal to the longitudinal direction of the heater (FIG. 2), the irradiation angle α at which the radiation from the heat distribution section 202c of the halogen heater 202A having a large amount of heat directly hits the fixing belt 201 is the halogen heater having a small amount of heat. It is preferable that the radiation from the heat distribution section 202d of 202B is larger than the irradiation angle β that directly hits the fixing belt 201. This applies to all embodiments described below.

For example, when the irradiation angle α of the halogen heater 202A is widened by 5% and the irradiation angle β of the halogen heater 202B is narrowed by 5%, the power amount of the fixing device in which the region in the fixing belt is equally divided is used as a reference. The amount of power P can be calculated theoretically as follows.
P (halogen heater 202A) = 770 × 1.05 = 808.5W
P (halogen heater 202B) = 440 × 0.95 = 418W
P (whole) = 808.5 + 418 = 1226.5W

On the other hand, when the heaters are arranged in the same region and have the same irradiation angle, the reference electric energy P can be calculated as follows.
P (halogen heater 202A) = 770W
P (halogen heater 202B) = 440W
P (whole) = 770 + 440 = 1210W

  As described above, according to the present embodiment, since the heating efficiency improvement amount of the halogen heater 202A having the wide heat distribution section 202c exceeds the heating efficiency reduction amount of the halogen heater 202B, the heater arrangement area is divided equally as a whole. Heating efficiency is improved from the configuration.

6 is a schematic perspective view of the inside of the fixing belt of the fixing device according to the second embodiment, FIG. 7 is a schematic perspective view when FIG. 6 is turned upside down, and FIG. 8 is a schematic cross-sectional view at the end of the device in FIG. FIG. 9 is a schematic cross-sectional view at the center of the apparatus of FIG. In the following, differences from the first embodiment will be mainly described.
Also in this embodiment, the fixing device 200 includes two halogen heaters 202A and 202B each having heat distribution portions 202c and 202d having different distributions in the longitudinal direction. Since the two halogen heaters 202A and 202B are arranged in the upper and lower separate areas 211 and 212 with the stay 207 interposed therebetween, the glass tubes are not heated when the heaters are turned on, so that the heating efficiency is not lowered.

  Here, the sizes of the regions 211 and 212 in which the halogen heaters are arranged are changed in accordance with the heat distribution part / heat distribution in the longitudinal direction of the halogen heaters. More specifically, the region where the heat distribution portions / heat distribution portions of the two halogen heaters 202A and 202B exist is expanded by the same ratio. For this purpose, the shape of the stay 207 is changed along the longitudinal direction. That is, the first partition part 207c and the second partition part 207e of the stay 207 facing the heat distribution part 202c of the halogen heater 202A in the center are away from the heat distribution part 202c and approach the non-heat distribution part 202e of the halogen heater 202B. (FIGS. 6 and 7). Further, the first partition portion 207c and the second partition portion 207e of the stay 207 facing the heat distribution portion 202d of the halogen heater 202B at both ends in the longitudinal direction are moved away from the heat distribution portion 202d and moved to the non-heat distribution portion 202f of the halogen heater 202A. It is formed so as to approach (FIGS. 6 and 7). In other words, the first region 211 in which the heat distribution unit 202c in the halogen heater 202A with a large amount of heat generation is disposed is wider than the first region 211 in which the heat distribution unit 202c is not disposed.

  Further, the second region 212 in which the heat distribution unit 202d in the halogen heater 202B with a small amount of heat generation is disposed is also expanded from the second region 212 in which the heat distribution unit 202d is not disposed. As a result, in the second region 212 where the heat distribution unit 202d in the halogen heater 202B is disposed, the non-heat distribution unit 202f in the halogen heater 202A is disposed so as to sandwich the stay 207 corresponding to the second region 212. Wider than the first region 211 (FIG. 8). Since the region where the heat source with a small amount of heat is arranged can be widened, the irradiation angle of the radiant heat hitting the fixing member from the heat source with a small amount of heat is also increased, and the thermal efficiency is improved. Therefore, the thermal efficiency as a fixing device is further improved.

  Therefore, at the end in the longitudinal direction shown in FIG. 8, the irradiation angle β of the halogen heater 202B increases by 5%, for example, while the irradiation angle α of the halogen heater 202A decreases by 5%, for example. However, since the longitudinal end portion of the halogen heater 202A corresponds to the non-heat distribution portion 202f, the radiation of the halogen heater 202A does not decrease. In the central portion in the longitudinal direction shown in FIG. 9, the irradiation angle β of the halogen heater 202B decreases by, for example, 5%, while the irradiation angle α of the halogen heater 202A increases, for example, by 5%. However, since the central portion in the longitudinal direction of the halogen heater 202B corresponds to the non-heat distribution portion 202e, the radiation of the halogen heater 202B does not decrease. Thus, since the irradiation angles α and β of the two halogen heaters 202A and 202B are both wide, the heating efficiency of both is improved. Therefore, the efficiency of the entire fixing device is improved as compared with the configuration of FIG.

  For example, the heat distribution unit 202c has a length of 217 mm, the halogen heater 202A has a power amount of 770 W, the heat distribution unit 202d has a length of 63 mm (126 mm in total), and the halogen heater 202B has a power of 440 W. Have quantity.

  However, both the amount of heat generated and the amount of power per unit length of the halogen heaters 202A and 202B are, for example, 3.5 W / mm. This is to keep the amount of heat applied to the toner and the recording material constant in order to keep the toner fixing property on the recording material and the glossiness of the image constant.

  Therefore, when both the irradiation angles α and β of the halogen heater 202A and the halogen heater 202B are wide by 5%, the power amount P based on the power amount of the fixing device in which the region in the fixing belt is equally divided is theoretically. It can be calculated as follows.

P (halogen heater 202A) = 770 × 1.05 = 808.5W
P (halogen heater 202B) = 440 × 1.05 = 462W
P (whole) = 808.5 + 462 = 1270.5W

  As described above, according to the present embodiment, the heating efficiency is further improved as compared with the first embodiment by widening the irradiation angles α and β of the heat distribution portions of the two halogen heaters.

Next, a fixing device according to the third embodiment will be described.
As described with respect to the first embodiment, even if the irradiation angles of some of the halogen heaters are narrowed, the irradiation angles of the other halogen heaters may be widened and the heating efficiency may be improved as a whole. Therefore, in the present embodiment, only the irradiation angle α of the halogen heater 202A that generates a large amount of heat and power is widened. In this case, the cross section of the fixing unit in the longitudinal direction is as shown in FIG. 2, and the cross section of the longitudinal end is as shown in FIG. That is, only the first region 211 where the heat distribution unit 202c is arranged in the halogen heater 202A having a large amount of heat generation is expanded from the first region 211 where the heat distribution unit 202c is not arranged. The second region 212 where the heat distribution unit 202d of the halogen heater 202B with a small amount of heat generation is disposed, and the non-heat distribution unit 202f of the halogen heater 202A with a large amount of heat generation, which is located across the stay 207 corresponding to the second region. The first region 211 in which is arranged has substantially the same area.

  Here, as can be seen from FIG. 2, the irradiation angle α of the halogen heater 202A is widened by, for example, 5% at the central portion in the longitudinal direction where the heat distribution section 202c of the halogen heater 202A is disposed. The angle β is narrowed by 5%. However, since the heat distribution part 202d of the halogen heater 202B is not disposed at the center in the longitudinal direction, the irradiation angle of the halogen heater 202B may be narrowed.

In this case, the power amount P based on the power amount of the fixing device in which the region in the fixing belt is equally divided can be theoretically calculated as follows.
P (halogen heater 202A) = 770 × 1.05 = 808.5W
P (halogen heater 202B) = 440 × 1 = 440W
P (whole) = 808.5 + 440 = 1248.5W

  As described above, according to the present embodiment, the heating efficiency is further improved as compared with the first embodiment by widening only the irradiation angle α of the halogen heater having a larger calorific value and electric power.

FIG. 11 is a schematic configuration diagram of a fixing device according to the fourth embodiment.
In this embodiment, the halogen heater 202A has a heat distribution unit 202c arranged in an area corresponding to the large size paper width, and the halogen heater 202B is arranged in an area corresponding to the small size paper width. 202d. The large size paper width corresponds to, for example, A4 horizontal or A3 vertical, and the small size paper width corresponds to, for example, A4 vertical or B5 vertical.

  Also in this embodiment, the fixing device 200 includes two halogen heaters 202A and 202B each having different heat distribution portions 202c and 202d. By arranging the two heaters 202A and 202B in separate upper and lower regions sandwiching the stay 207, the glass tubes are not heated when the heater is turned on, so that the heating efficiency is not lowered.

  The stay 207 is formed in the same manner as that shown in FIG. That is, the first partition portion 207c of the first member 207A of the stay 207 and the second partition portion 207e of the second member 207B of the stay 207 have substantially the same length throughout the longitudinal direction (the direction perpendicular to the paper surface). The first fixing portion 207d is longer than the second fixing portion 207f. The first partition part 207c and the second partition part 207e extend linearly in the longitudinal direction of the heater. The cross section of the central portion in the longitudinal direction is the same as that in FIG. However, illustration of the reflecting member 209 is omitted in FIG.

  Therefore, in the fixing belt 201, the first area 211 is generally wider than the second area 212. Therefore, the heating efficiency is improved as the irradiation angle of the halogen heater 202A with a large amount of heat generation / power is increased, and the heating efficiency is decreased as the irradiation angle of the halogen heater 202B with a small amount of heat generation / power is narrowed. As a result, the heating efficiency of the entire fixing device is improved as compared with the fixing device in which the area in the fixing belt is equally divided.

  As described above, among the plurality of heat sources, the region where the heat source with a large amount of heat is disposed is larger than the region where the heat source with a small amount of heat is disposed, so that radiant heat from the heat source with a large amount of heat to the fixing member is reduced. The irradiation angle is increased and the efficiency is improved.

  The fixing device of each embodiment includes two heat sources, but is not limited thereto. For example, the fixing device may include three heat sources each having a heat distribution portion with a different distribution in the longitudinal direction, and the three heat sources may be arranged in three separate regions with the support member interposed therebetween. Of the three heat sources, a heat source having a larger calorific value may be disposed in a wider area of the region, and a heat source having a smaller calorific value may be disposed in a narrower region of the area.

  The stay 207 only needs to satisfy the function of receiving the pressure from the pressure roller 205 to support the nip forming member 206, so the cross section of the stay 207 is not limited to the T-shape, and is configured only by a partition portion. It may be I-shaped.

201 Fixing belt (fixing member)
202A, 202B Halogen heater (heat source)
203 Pressure roller (Pressure member)
206 Nip forming member 207 Stay (support member)
N Nip part

JP 2004-286922 A Japanese Patent No. 2861280 JP 2007-334205 A JP 2010-78839 A JP 2014-240952 A JP 2014-056203 A

Claims (10)

A rotatable fixing member, and a pressure member which is arranged opposite to the fixing member and is rotatable,
A plurality of heat sources for heating the fixing member inside the fixing member, a nip forming member for forming a nip portion with the pressure member via the fixing member, and a support for supporting the nip forming member The member is placed,
In a fixing device for fixing a toner image on a recording material at the nip portion,
The plurality of heat sources each have a heat distribution portion with a different distribution in the longitudinal direction, and are arranged in different regions across the support member,
The fixing device, wherein a heat source having a large calorific value among the plurality of heat sources is arranged in a wide area of the area, and a heat source having a small calorific value is arranged in a narrow area of the area.   The fixing device according to claim 1, wherein the region where the heat distribution unit is disposed in the heat source having a large amount of heat generation is wider than the region where the heat distribution unit is not disposed.   The fixing device according to claim 2, wherein the region where the heat distribution unit is disposed in the heat source having a small amount of heat generation is wider than the region where the heat distribution unit is not disposed. The support member has a partition for partitioning the plurality of heat sources,
The fixing device according to claim 1, wherein the partition portion is formed to be away from the heat distribution portion. The support member has a partition for partitioning the plurality of heat sources,
The fixing device according to claim 1, wherein the partition part extends linearly in a longitudinal direction of the plurality of heat sources.   The fixing device according to claim 1, further comprising a reflective member between the heat distribution section of the plurality of heat sources and the support member.   The plurality of heat sources have the same calorific value per unit length, and the heat distribution unit of the heat source with the large calorific value is longer than the heat distribution unit of the heat source with the small calorific value. The fixing device according to claim 1.   In a cross section orthogonal to the longitudinal direction of the plurality of heat sources, an irradiation angle at which radiation from the heat source having a large heat generation amount directly hits the fixing member is from the heat distribution portion of the heat source having a small heat generation amount. The fixing device according to claim 1, wherein the radiation is larger than an irradiation angle directly hitting the fixing member.   The heat source having a large heat generation amount is a central heater that heats the longitudinal center portion of the fixing member, and the heat source having a small heat generation amount is an end heater that heats the longitudinal end portion of the fixing member. The fixing device according to any one of claims 1 to 8. An image forming apparatus comprising the fixing device according to claim 1.

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