Patent Grant
11256203
This application claims priority from Japanese Patent Application No. 2020-040646, filed on Mar. 10, 2020, the entire subject matter of which is incorporated herein by reference.
An aspect of the present disclosure is related to a fuser.
A fuser having, for example, a ceramic heater, a fusing belt, and a heater holder, is known. The fusing belt may be an endless belt and have an inner circumferential surface that contacts the ceramic heater. The heater holder may retain the ceramic heater and contact the inner circumferential surface of the fusing belt to guide the fusing belt there-along. The fusing belt may be heated by the ceramic heater and rotate around the ceramic heater so that a recording medium having an image thereon may be heated through the fusing belt.
For another example, a heater having a metal-made base plate may be employed in a fuser. The base plate may be manufactured in pressing or shearing works and may have a shear drop on an edge on one side and a burr or a sharpened edge on the other side thereof. The sharpened edges and the burrs on the edges of the base plate may damage the inner circumferential surface of the fusing belt; therefore, with the sharpened edges and burrs, it may be difficult to improve durability of the fusing belt.
The present disclosure is advantageous in that a fuser, in which durability of the belt may be improved, is provided.
According to an aspect of the present disclosure, a fuser having a heater, a belt, and a holder, is provided. The heater includes a metal-made base plate and a resistive-heating element. The heater has a first face extending in a lengthwise direction and a widthwise direction and a second face facing reversely from the first face. The resistive-heating element is formed on at least one of the first face and the second face. The belt being an endless belt has an inner circumferential surface. The inner circumferential surface is in contact with the first face of the heater. The belt is configured to rotate around the heater. The holder has a retainer face configured to contact the second face of the heater to retain the heater and a belt-guiding face configured to contact the inner circumferential surface of the belt and guide the belt there-along. The base plate has a pair of first edges located on one end and the other end of the first face in the widthwise direction. The pair of first edges are rounded at ridges extending in the lengthwise direction.
Hereinafter, first through third embodiments of the present disclosure will be described with reference to the accompanying drawings.
As shown in
<Overall Configuration of the Image Forming Apparatus>
As shown in
The main body 2 may include a casing and frames which are not shown in the drawings. At a lower position in the main body 2, a sheet cassette 2C may be detachably attached. In the sheet cassette 2C, sheets SH, on which images may be formed, may be stacked. The sheets SH may be, for example, paper sheets or OHP sheets.
The main body 2 has an ejection tray 2D formed on a top face thereof. On the ejection tray 2D, the sheets SH with the images formed thereon being ejected outside the casing may be placed. At a frontward area in the main body 2, the feeder 20 is arranged. The feeder 20 may convey the sheets SH stored in the sheet cassette 2C to the process cartridge 7. At a rearward area in the main body 2, the fuser 5 is arranged. The fuser 5 may apply heat and pressure to the sheet SH conveyed through the process cartridge 7.
Inside the main body 2, a conveyer path P1 is formed. The conveyer path P1 is a path extending upward from a frontward end of the sheet cassette 2C and turning in a shape of U, extending rearward therefrom approximately horizontally, through the process cartridge 7 and the fuser 5, turning upward in another shape of U, and through the ejection device 29 to the ejection tray 2D.
The feeder 20 includes a feed roller 21, a separation roller 22, and a separation pad 22A, which may feed the sheets SH stored in the sheet cassette 2C to the conveyer path P1 one by one. The feeder 20 further includes a conveyer roller 23A and a pinch roller 23P; and a registration roller 24A and a pinch roller 24P; which are arranged along the conveyer path P1 to convey the sheets SH to the process cartridge 7.
The process cartridge 7 includes a developing agent container 7A, a photosensitive drum 7B, a developing roller 7C, and a charger 7D, which may be in a known configuration.
The scanner 8 is located at an upper position with respect to the process cartridge 7. The scanner 8 may include a laser-beam emitter, a polygon mirror, an fθ lens, and a reflection mirror, which may be in known configurations. The scanner 8 may emit a laser beam from the upper position at the photosensitive drum 7B in the process cartridge 7.
As the photosensitive drum 7B rotates, a surface of the photosensitive drum 7B may be positively charged evenly by the charger 7D and exposed to the scanning laser beam emitted from the scanner 8. Thereby, an electrostatic latent image, which corresponds to an image to be formed on the sheet SH, may be formed on the surface of the photosensitive drum 7B. The developing roller 7C may supply a developing agent from the developing agent container 7A to the electrostatic latent image. Thereby, an image may be formed in the developing agent on the surface of the photosensitive drum 7B. The image in the developing agent may be transferred onto the sheet SH being conveyed through the process cartridge 7.
The fuser 5 is located at a position rearward with respect to the process cartridge 7. The fuser 5 includes a heating unit 50, which is located on an upper side of the conveyer path P1, and a pressure roller 59, which is located on a lower side of the conveyer path P1 to face the heating unit 50 across the conveyer path P1. One of the heating unit 50 and the pressure roller 29 is urged against the other of the heating unit 50 and the pressure roller 29 by an urging device, which is not shown. The pressure roller 59 may rotate about a rotation axis X59. The fuser 5 may nip the sheet SH between the heating unit 50 and the pressure roller 59 to thermally fuse and fix the image in the developing agent onto the sheet SH.
The ejection device 29 includes an ejection roller 29A and an ejection-pinch roller 29P, which may eject the sheet SH with the image formed in the developing agent and fixed thereon at the ejection tray 2D.
<Detailed Configuration of the Fuser>
As shown in
The heater 30 has a form of an approximately rectangular plate, which has a first face 30A and a second face 30B. The first face 30A faces downward and extends in a conveying direction D1, which is a direction to convey the sheet SH in the fuser 5, and in the rotation axis X59 of the heat roller 59, which is parallel to a crosswise direction of the sheet SH conveyed in the fuser 5. In other words, the first face 30A is arranged to lie above and along the sheet SH being conveyed in the fuser 5. The second face 30B faces reversely from the first face 30A, i.e., upward.
In the following paragraphs, the direction of the rotation axis X59 of the pressure roller 59 may be called as a lengthwise direction, and the conveying direction D1, in which the sheet SH is conveyed in the fuser 5, may be called as a widthwise direction.
As shown in
The belt 55 is a heat-resistant and flexible tubular member, as shown in
The stay 54 may be made of a piece of rigid plate, e.g., a steel plate, by being bent in a cross-sectional form of a vertically reversed U. The stay 54 extends in the direction of the rotation axis X59 in an arrangement not contacting the inner circumferential surface 55A of the belt 55.
The holder 60 is a heat-resistant resin-made member. The holder 60 is attached to a lower part of the stay 54 and is supported by the stay 54. The holder 60 has a heater accommodative portion 69 and a belt guiding face 65.
The heater accommodative portion 69 is a portion recessed upward from a lower face of the holder 60 at a central area in the conveying direction D1 and extending in the direction of the rotation axis X59. A length between an inner side face of the heater accommodative portion 69 on an upstream side in the conveying direction D1 and an inner side face of the heater accommodative portion on a downstream side in the conveying direction D1 is slightly larger than the length of the heater 30 in the conveying direction D1.
The heater accommodative portion 69 includes a retainer face 64. The retainer face 64 is an inner and upper face, or a ceiling, of the heater accommodative portion 69 facing downward and spreading in the direction of the rotation axis X59 and the conveying direction D1. As shown in
As shown in
The pair of grooves 64A, 64B are recessed upward and elongated to thinly extend in the direction of the rotation axis 59. As shown in
As shown in
As shown in
As shown in
The belt-guiding face 65 is a curved face formed in the holder 60 on an upstream side and a downstream side of the heater accommodative portion 69 in the conveying direction D1. The belt-guiding face 65 includes a pair of guiding edges 65A, 65B.
The guiding edge 65A on the upstream side in the conveying direction D1 is connected to a lower end of the inner side face of the heater accommodative portion 69 on the upstream side in the conveying direction D1 and extends in the direction of the rotation axis X59. The guiding edge 65B on the downstream side in the conveying direction D1 is connected to a lower end of the inner side face of the heater accommodative portion 69 on the downstream side in the conveying direction D1 and extends in the direction of the rotation axis X59. The guiding edges 65A, 65B are rounded ridges.
The belt-guiding face 65 on the upstream side in the conveying direction D1 extends upstream from the guiding edge 65A on the upstream side in the conveying direction D1 and curves upward. The belt-guiding face 65 on the downstream side in the conveying direction D1 extends downstream from the guiding edge 65B on the downstream side in the conveying direction D1 and curves upward.
The belt-guiding face 65 contacts the inner circumferential surface 55A of the belt 55 and guide the belt 55 there-along. Thus, the belt 55 may rotate around the heater 30, the holder 60, and the stay 54.
The pressure roller 59 includes a rotation shaft 59A, which is centered at the rotation axis X59 and may be made of metal; and an elastic layer 59B, which covers the rotation shaft 59A. The pressure roller 59, in conjunction with the heater 30, nips the belt 55 at a position between the pressure roller 59 and the heater 30. In other words, the pressure roller 59 and the heater 30 form a nipping portion N1, at which the heat and the pressure may be applied to the sheet SH.
The pressure roller 59 may be driven by a driving force transmitted from a motor, which is not shown but may be arranged inside the main body 2, and rotate to apply a conveying force to the sheet SH. The belt 55 may be driven by the driving force transmitted either directly from the rotating pressure roller 59 or indirectly through the sheet SH moving in the nipping portion N1.
Thus, with the inner circumferential surface 55A of the belt 55 contacting the first face 30A of the heater 30, the belt 55 may be heated by the heater 30, rotate around the heater 30, and, in conjunction with the pressure roller 59, apply heat and pressure to the sheet SH moving in the nipping portion N1. Thereby, the image formed in the developing agent may be thermally fixed onto the sheet SH.
<Detailed Configuration of the Heater>
As shown in
In the cross-sectional views of the heater 30, as shown in
The base plate 40 is a plate member made of metal such as, for example, stainless steel, and has a predetermined thickness. The base plate 40 includes a first plate face 40A and a second plate face 40B. The first plate face 40A is a plane facing downward and spreading in the direction of the rotation axis X59 and the conveying direction D1. The second plate face 40B is a plane facing reversely from the first plate face 40A, i.e., upward, and spreads in parallel to the first plate face 40A. The thickness of the base plate 40 may mean a dimension in the vertical direction.
As shown in
As shown in
The second plate face 40B of the base plate 40 has a pair of second edges 42A, 42B. The second edges 42A, 42B are located on one end and the other end of the second face 30B of the heater 30 in the widthwise direction, respectively, in other words, on an upstream end and a downstream end of the second face 30B in the conveying direction D1, respectively. The second edges 42A, 42B extend in the lengthwise direction of the heater 30, in other words, in the direction of the rotation axis X59.
The base plate 40 may be formed in pressing works using, for example, known die-and-punch tools.
While illustration of the die is omitted in the drawings, the die may be formed to have a pierced hole, which is in a form corresponding to the outline of the base plate 40. The punch may have a protrusive form protruding downward. On a lower face of the punch, a puncher head may be formed, and a cutting blade may be formed along an outer circumference of the puncher head.
The metal plate being a base material of the base plate 40 may be, for example, made of a rolled sheet of steel: the sheet of steel may be drawn out from the roll and placed on the die. The punch may descend toward the pierced hole formed in the die, and as the punch shears through the metal plate on the die with the cutting blades in the die and in the punch, the base plate 40 may be formed. When the punch shears through the metal plate, on an outer circumferential edge of the base plate 40 on the face that contacted the puncher head of the punch, burrs may be formed; and on an outer circumferential edge of the base plate 40 on the other face that did not contact the puncher head of the punch, shear drops may be formed.
In the present embodiment, the second plate face 40B is the face of the base plate 40 that contacts the puncher head of the punch, and the first plate face 40A of the base plate 40 faces reversely from the face that contacts the puncher head of the punch.
Therefore, in the pair of first edges 41A, 41B, shear drops curving toward the second face 30B in the direction of thickness of the base plate 40 are formed. The shear drops in the first edges 41A, 41B are rounded at ridges extending in the direction of the rotation axis X59.
Meanwhile, in the pair of second edges 42A, 42B, burrs protruding in the direction of thickness of the base plate 40 to point away from the first face 30A are formed. The burrs in the second edges 42A, 42B protrude to taper pointing upward and extend in the direction of the rotation axis X59.
In the cross-sectional view of the heater 30, for a purpose of easier understanding, the burrs and the shear drops are shown in relatively exaggerated sizes.
Manufacturers may consider, for example, forming the base plate 40 in etching works, in which a part of the metal plate to form the base plate 40 is masked, and the other unmasked part of the metal plate is etched by the corrosive effect of the etchant, since burrs and shear drops may less likely be formed on the outer circumferential edges of the base plate 40 in the etching works. However, manufacturing costs may increase in the etching works compared to the pressing works.
The first glass layer 31 is in a two-layered formation including an insulating layer 34 and a protective layer 35. The insulating layer 34 is formed on the first plate face 40A of the base plate 40, and the protective layer 35 is formed on the insulating layer 34 to cover the insulating layer 34.
As shown in
As shown in
The protective layer 35 covers the resistive-heating element 39 except the connector terminals 39T. The connector terminals 39T may contact mating terminals of a connector, which is not shown. The resistive-heating element 39, when powered through the connectors 39T, may generate heat.
As shown in
The first face 30A of the heater 30 is formed of a lower face of the protective layer 35 and the exposed part of the first plate face 40A including the pair of first edges 41A, 41G and the peripheries thereof.
The second face 30B of the heater 30 is formed of an upper face of the second glass layer 32, and the exposed part of the second plate face 40B including the pair of second edges 42A, 42G and the peripheries thereof.
In the condition where the heater 30 is accommodated in the heater accommodative portion 69, the retainer face 64 contacts the upper face of the first glass layer 32, and the lower face of the protective layer 35 in the first glass layer 31 contacts the inner circumferential surface 55A of the belt 55.
In the condition where the heater 30 is accommodated in the heater accommodative portion 69, the guiding edges 65A, 65B on the belt-guiding face 65 extend in the direction of the rotation axis X59 at positions in adjacent to the first edges 41A, 41B of the base plate 40, respectively. The pair of guiding edges 65A, 65B protrude in the direction of thickness of the base plate 40 for a distance L1 from the pair of first edges 41A, 41B on a side of the pair of first edges 41A, 41B opposite to the second face 30B.
The lower face of the protective layer 35 in the first glass layer 31 is retracted in the direction of the thickness of the base plate 40 from the pair of guiding edges 65A, 65B toward the second face 30B for a distance L2.
The grooves 64A, 64B located on the upstream end and the downstream end of the retainer face 64 in the conveying direction D1 overlap the second edges 42A, 42B of the base plate 40, respectively, in the direction of thickness of the base plate 40. Although forms and sizes of the burrs that may be formed on the second edges 42A, 42B may not always be identical, pointing ends of the burrs may enter the grooves 64A, 64B, respectively.
The contact portion 63A shown in
Although not shown in
<Benefits>
In the fuser 5 according to the first embodiment, as shown in
Thus, the durability of the belt 55 in the fuser 5 may be improved.
Moreover, the heater 30 in the fuser 5 has the first glass layer 31, which is formed on the first face 30A of the heater 30. Meanwhile, the pair of first edges 41A, 41B are exposed without being covered. In this arrangement, the inner circumferential surface 55A of the belt 55 may contact the heater 30 mainly on the lower face of the first glass layer 31. Therefore, slidability of the belt 55 on the heater 30 may be improved. Moreover, while the pair of first edges 41A, 41B are exposed, the pair of first edges 41A, 41B forming the shear drops may be less likely to damage the inner circumferential surface 55A of the belt 55. In this regard, compared to a hypothetical configuration, in which the first glass layer 31 are extended to cover the pair of first edges 41A, 41B, a manufacturing process to form the first layer 31 in the heater 30 may be simplified.
Moreover, the resistive-heating element 39 in the fuser 5 is interposed between the insulating layer 34, which is formed on the first plate face 40A of the base plate 4, and the protective layer 35, which is formed on the insulating layer 34. In this arrangement, compared to a hypothetical configuration, in which the resistive-heating element 39 is formed on the second face 30B, the belt 55 may be heated efficiently, and the insulating ability of the resistive-heating member 39 may be improved.
Moreover, the pair of guiding edges 65A, 65B of the belt-guiding face 65 in the fuser 5 protrude in the direction of thickness of the base plate 40 for the distance L1 from the pair of first edges 41A, 41B in the direction opposite to the second face 30B. In this arrangement, the inner circumferential surface 55A of the belt 55 may be restrained from contacting the first edges 41A, 41B. Therefore, durability of the belt 55 may be improved.
Moreover, the pair of second edges 42A, 42B of the base plate 40 overlap the pair of grooves 64A, 64B located on the upstream side and the downstream side of the retainer face 64 of the holder 60 in the conveying direction D1. In this arrangement, the pointing ends of the burrs formed on the second edges 42A, 42B may not contact the retainer face 64. Therefore, the retainer face 64 of the holder 60 may retain the heater 30 closely attached thereto, without pushing the heater 30 away, at the correct position.
Moreover, the contact portion 63A shown in
Moreover, as shown in
Moreover, as shown in
Moreover, in the fuser 5, the lower face of the protective layer 35 in the first glass layer 31 is located at the position retracted in the direction of thickness of the base plate 40 from the pair of guiding edges 65A, 65B toward the second face 30B for the distance L2. Therefore, the pair of first edges 41A, 41B may be separated from the inner circumferential surface 55A of the belt 55. As a result, contact between the first edges 41A, 41B and the inner circumferential surface 55A of the belt 55 may be restrained effectively, and the durability of the belt 55 may be improved further.
As shown in
Moreover, in the fuser in the second embodiment, the second edge 42A of the base plate 40 on the upstream side in the conveying direction D1 may form a sharp edge rather than a burr. Although not shown in
The sharp edge in this context may refer to a form of a ridge, which is not rounded but is pointing. The sharp edge may be formed by, for example, removing burrs by cutting or grinding.
The groove 64A on the upstream side in the conveying direction D1 may overlap the sharp edge on the second edge 42A on the upstream side in the conveying direction D1. The contact portion 63A on the upstream side in the conveying direction may contact the sharp edge on the second edge 42A on the upstream side in the conveying direction D1.
Although not shown in
The remainder of the fuser in the second embodiment may be similar to the fuser 5 in the first embodiment. Therefore, in the following paragraphs, items or structures which are substantially the same as or similar to those described in the first embodiment may be denoted by the same reference signs, and description of those may be omitted.
In the fuser according to the second embodiment, similarly to the fuser 5 in the first embodiment, durability of the belt 55 may be improved.
Moreover, the pair of second edges 42A, 42B of the base plate 40 overlap the pair of grooves 64A, 64B located on the upstream side and the downstream side of the retainer face 64 of the holder 60 in the conveying direction D1. In this arrangement, the sharp edges formed on the second edges 42A, 42B may not contact the retainer face 64. Therefore, the retainer face 64 of the holder 60 may retain the heater 30 closely attached thereto, without pushing the heater 30 away, at the correct position.
Moreover, in the fuser of the second embodiment, with the pair of contact portions 63A, 63B being arranged to contact the sharp edges on the pair of second edges 42A, 42B, the heater 30 may be restrained from moving relatively to the holder 60 in the direction of the rotation axis X59.
While in the fuser 5 in the first embodiment the lower face of the protective layer 35 in the first glass layer 31 is retracted in the direction of the thickness of the base plate 40 from the pair of guiding edges 65A, 65B toward the second face 30B for the distance L2, in a fuser in the third embodiment, as shown in
The remainder of the fuser in the third embodiment may be similar to the fuser 5 in the first embodiment. Therefore, in the following paragraphs, items or structures which are substantially the same as or similar to those described in the first embodiment may be denoted by the same reference signs, and description of those may be omitted.
In the fuser according to the third embodiment, similarly to the fuser 5 in the first embodiment or the fuser in the second embodiment, durability of the belt 55 may be improved.
Moreover, in the fuser of the third embodiment, the lower face of the protective layer 35 in the first glass layer 31 protrudes in the direction of the thickness of the base plate 40 for the distance L3 from the pair of guiding edges 65A, 65B on the side of the guiding edges 65A, 65B opposite to the second face 30B. In this arrangement, the pair of guiding edges 65A, 65B may be restrained from affecting the contacting condition between the first glass layer 31 and the inner circumferential surface 55A of the belt 55. Therefore, slidability of the belt 55 on the heater 30 may be improved.
Although examples of carrying out the invention have been described, those skilled in the art will appreciate that there are numerous variations and permutations of the fuser that fall within the spirit and scope of the disclosure as set forth in the appended claims. It is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or act described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
For example, the base plate 40 may not necessarily be formed in the pressing works but may be formed in, for example, laser-cutting works. When the base plate is formed in the laser-cutting works, shear drops may be formed on a face, at which the laser beam is emitted. Therefore, the base plate may be set in an arrangement such that the face, at which the laser beam was emitted, should face the first face of the heater. For another example, the base plate may be formed in cutting works, and shear drops in the pair of first edges of the base plate may be formed by cutting works as well.
For another example, the base plate 40 may not be a plane or flat plate but may be curved to have a cross-sectional shape of an arc that curves orthogonally to the lengthwise direction.
For another example, at least one of the pair of contact portions 63A, 63B may be omitted.
For another example, the resistive-heating element 39 may not necessarily be formed on the first face 30A of the heater 30 but may be formed on the second face 30B or may be formed on both the first face 30A and the second face 30B of the heater 30.
For another example, the thickness of the second glass layer 32 may not necessarily be so large as to allow the pointing ends of the burrs formed on the second edges 42A, 42B to enter the grooves 64A, 64B, respectively, as shown in
The fuser in the present disclosure may be applicable to, for example, an image forming apparatus and a multifunction peripheral machine.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2020-040646 | Mar 2020 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6583389 | Murooka | Jun 2003 | B2 |
| 20030035667 | Izawa | Feb 2003 | A1 |
| 20150277309 | Kuroda | Oct 2015 | A1 |
| 20170176907 | Sawada | Jun 2017 | A1 |
| 20170261899 | Gotoh | Sep 2017 | A1 |
| 20200004182 | Yabuki | Jan 2020 | A1 |
| 20210103239 | Miyata | Apr 2021 | A1 |
| Number | Date | Country |
|---|---|---|
| H05-134570 | May 1993 | JP |
| H10-133502 | May 1998 | JP |
| 2001222180 | Aug 2001 | JP |
| 2004-093 842 | Mar 2004 | JP |
| 2015-191734 | Nov 2015 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20210286296 A1 | Sep 2021 | US |
