This application claims priority from Japanese Patent Application No. 2020-072045, filed on Apr. 14, 2020, the entire subject matter of which is incorporated herein by reference.
An aspect of the present disclosure is related to a fuser having a planar heater.
A fuser having a planar heater is known. The heater may be attached to a holder through a connector and a clip. For example, the connector may nip the heater and the holder at an end area of the heater on one side in a lengthwise direction, and the clip may nip the heater and the holder at the other end area on the other side in the lengthwise direction. The clip may be in a form of a leaf spring having a breadth of some extent along the lengthwise direction.
In order to reserve a lengthwise range to attach the clip with the breadth in the heater and the holder, a dimension of the heater and the holder in the lengthwise direction may be increased.
The present disclosure is advantageous in that a fuser, in which lengthwise dimensions of a heater and a holder may be reducible, is provided.
According to an aspect of the present disclosure, a fuser having a heater, a holder, and a first wire spring, is provided. The heater is in a form of a planar plate and has a first face and a second face opposite to the first face. The holder has a supporting base. The supporting base supports the first face of the heater. The first wire spring retains the heater on the holder. The first wire spring has a first facing portion facing and supporting the second face of the heater, a first engageable portion, and a second engageable portion. The first engageable portion extends from one end of the first facing portion, and is engageable with the holder in an end area on one side of the heater in a widthwise direction. The widthwise direction intersects orthogonally with a lengthwise direction of the heater. The second engageable portion extends from the other end of the first facing portion and is engageable with the heater in an end area on the other side of the heater in the widthwise direction.
Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. As shown in
The feeder 3 is located at a lower position in the casing 2 and includes a feeder tray 31, a lifting plate 32, and a feeder device 33. The feeder tray 31 may store sheets S therein. The sheets S may be lifted upward by the lifting plate 32 and fed to the process cartridge 5 by the feeder device 33.
The exposure device 4 is located at an upper position in the casing 2 and includes a light source, which is not shown, and polygon mirrors, lenses, and reflective mirrors, which are shown in
The process cartridge 5 is located at a lower position with respect to the exposure device 4 and is detachable from the casing 2 through an opening, which is exposed when a front cover 21 on the casing 2 is open. The process cartridge 5 includes a drum unit 6 and a developing unit 7. The drum unit 6 includes the photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is detachable from the drum unit 6 and includes a developing roller 71, a supplier roller 72, a flattening blade 73, and a container 74 to contain a toner.
In the process cartridge 5, the surface of the photosensitive drum 61 may be charged evenly by the charger 62 and exposed to the laser beam from the light source in the exposure device 4. Thereby, an electrostatic latent image based on the image data may be formed on the photosensitive drum 61. Meanwhile, the toner in the container 74 may be supplied to the developing roller 71 through the supplier roller 72 and enter a position between the developing roller 71 and the flattening blade 73. The toner may be flattened evenly by the flattening blade 73 to form an evenly flattened layer on the developing roller 71. The toner may be thereafter supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. Thus, the electrostatic latent image may be developed to form a visible toner image on the photosensitive drum 61. As the sheet S is conveyed through a position between the photosensitive drum 61 and the transfer roller 63, the toner image on the photosensitive drum 61 may be transferred onto the sheet S.
The fuser 8 is located at a position downstream from the process cartridge 5 in a conveying direction, in which the sheet S is conveyed. The sheet S with the toner image transferred thereon may be conveyed through the fuser 8 to have the toner image fixed thereon by fusing. The sheet S with the toner image fused thereon may be ejected outside the casing 2 by conveyer rollers 23, 24 to rest on an ejection tray 22.
As shown in
The heater unit 81 includes a heater 110, a holder 120, a stay 130, and a belt 140. The heater 110 may be an elongated planar plate and has a first face 111 and a second face 112 being on a reverse side of the first face 111. The heater 110 is supported by the holder 120 at the first face 111. In the following description, a direction of longer sides of the heater 110 may be called as a lengthwise direction, and a direction of shorter sides of the heater 110 may be called as a widthwise direction.
The holder 120 may be made of, for example, resin and has a guide face 121 and a supporting base 122. The guide face 121 may contact an inner circumferential surface 141 of the belt 140 and guide the belt 140. The supporting base 122 has a supporting face 122A to support the heater 110. The stay 130 supports the holder 120 and may be formed by bending a plate having greater rigidity than the holder 120, e.g., a steel plate, into an approximate shape of U in a cross-sectional view.
The belt 140 is an endless belt having heat-tolerance properties and flexibility and includes a base tube made of metal such as stainless steel and a fluorine resin layer coating the metal base tube. The heater 110, the holder 120, and the stay 130 are arranged inside the belt 140. The belt 140 is arranged to rotate around the heater 110, the holder 120, and the stay 130. The inner circumferential surface 141 of the belt 140 contacts the heater 110.
The pressure roller 82 includes a shaft 82A made of metal and an elastic layer 82 coating the shaft 82A. The pressure roller 82 forms a nipping portion NP, in which the belt 140 is nipped between the heater 110 and the pressure roller 82 to apply heat and pressure to the sheet S.
The pressure roller 82 may be driven by a driving force transmitted from a motor, which is not shown but is located inside the casing 2, to rotate. As the pressure roller 82 rotates, a friction force produced between the pressure roller 82 and the belt 140 or the sheet S may cause the belt 140 to rotate passively. Thus, the transferred toner image may be thermally fixed to the sheet S as the sheet S is conveyed between the pressure roller 82 and the heated belt 140.
As shown in
Each rail 150A may be in a columnar form extending from a body 150B of the fuser frame 150 in the thickness direction. The paired rails 150A face each other along the widthwise direction. Faces of the paired rails 150 that face each other may contact contacting areas F in the holder 120 (see
The supporting baser 112 in the holder 120 has at least one opening for at least one temperature sensor. In particular, as shown in
As shown in
The first wire spring 40A is located between the belt 140 and the first connector 50A. The second wire spring 40B is located between the belt 140 and the second connector 50B. A shortest distance between the first wire spring 40A and the belt 140 and a shortest distance between the second wire spring 40B and the belt 140 are both shorter than a shortest distance between the first connector 50A and the belt 140 and than a shortest distance between the second connector 50B and the belt 140. Moreover, the shortest distance between the first wire spring 40A and the belt 140 is shorter than a shortest distance between the first wire spring 40A and the first connector 50A and than a shortest distance between the second wire spring 40B and the second connector 50B. Furthermore, the shortest distance between the second wire spring 40B and the belt 140 is shorter than the shortest distance between the first wire spring 40A and the first connector 50A and than the shortest distance between the second wire spring 40B and the second connector 50B. The first and second wire springs 40A, 40B and the first and second connectors 50A, 50B will be described further below.
Next, a structure of the holder 120 at each end area in the lengthwise direction will be described below. The structure of the holder 120 at the lengthwise end areas are symmetrical; therefore, one of the end areas on one side in the lengthwise direction will be representatively described.
As shown in
The side wall 124 protruding from the supporting face 122A is arranged along a periphery of the supporting base 122. The side wall 124 includes two (2) side walls 124 that extend along the lengthwise direction. The first contact portion 125 protrudes in the widthwise direction from one of the side walls 124 that extend along the lengthwise direction. The second contact portion 126 protrudes in the widthwise direction from the other of the side walls 124 that extend along the lengthwise direction. The first contact portion 125 and the second contact portion 126 provide the contacting areas F, which may contact the rails 1250A. A dimension of the first contact portion 125 and a dimension of the second contact portion 126 in the lengthwise direction are both larger than a lengthwise dimension of the faces of the rails 150 that face each other. The second contact portion 126 has a protrusive portion 126A, which may restrict the holder 126 from moving with respect to the rails 150A in the lengthwise direction. With the protrusive portion 126A, the holder 120 may be located at a correct position in the lengthwise direction with respect to the fuser frame 150. The first groove 127 is located in the side wall 124 between the first contact portion 125 and the supporting face 122A. The second groove 128 is located in the side wall 124 between the second contact portion 126 and the supporting face 122A. The protrusive portion 129 may, as described further in detail, engage with grooves 513 in the first and second connectors 50A, 50B.
As shown in
Next, structures of the first and second wire springs 40A, 40B will be described below. As shown in
The second wire spring 40B includes a second facing portion 41B, a third engageable portion 42B, and a fourth engageable portion 43B. The second facing portion 41B faces the second face 112 of the heater 110 and supports the second face 112. The second facing portion 41B extends straight in the widthwise direction across the second face 112. The third engageable portion 42B extends from one end of the second facing portion 41B and may engage with the holder 120 on the one side in the widthwise direction. The fourth engageable portion 43B extends from the other end of the second facing portion 41B and may engage with the holder 120 on the other side in the widthwise direction.
The first wire spring 40A and the second wire spring 40B have the same form and are located at symmetrical positions in the lengthwise direction. Therefore, in the following paragraphs, the first wire spring 40A will be representatively described.
The first wire spring 40A may be a piece of metal wire bent in a form as shown in
As shown in
The first facing portion 41A may fit in and engage with the first groove 127 and the second groove 128. As shown in
The first engageable portion 42A may be restrained from moving in the thickness direction by the first stopper portion 125B and separating from the holder 120. The second engageable portion 43A is restrained from moving in the thickness direction by the second stopper portion 126B and separating from the holder 120. The first stopper portion 125B is located to be closer to the first facing portion 41A than the first turnback portion 422 and overlaps the first turnback portion 422 in a view along the thickness direction. The second stopper portion 126B is located to be closer to the first facing portion 41A than the second turnback portion 432 and overlaps the second turnback portion 432 in the view along the thickness direction.
The first engageable portion 42A and the second engageable portion 43A contact the stay 130, and the stay 130 is electrically grounded. Therefore, the first wire spring 40A is grounded through the stay 130. Alternatively, the first engageable portion 42A and the second engageable portion 43A may be grounded by being indirectly connected to the stay 130 through conductive members such as metal wires.
Next, structure of the first and second connectors 50A, 50B will be described below. The first and second connectors 50A, 50B have a same structure; therefore, the first connector 50A will be described representatively and may be called as the connector 50A. The connector 50A may supply power to the heater 110. As shown in
One and the other of the electrodes 52 are connectable to one and the other of power-supply terminals T, respectively, and align spaced apart from each other along the lengthwise direction. The electrodes 52 are connected to a power source through wires, which are not shown.
The connector body 51 includes a base portion 510 having a rectangular shape, a first extended portion 511 and a second extended portion 512, which extend from the base portion 510 to the heater 110. The first extended portion 511 and the second extended portion 512 are spaced apart from each other and align in the thickness direction. The first extended portion 511 and the second extended portion 512 may nip the heater 110 and the holder 120 in the thickness direction.
On a surface of the second extended portion 512 that faces toward the first extended portion 511, a groove 513 is formed. The groove 513 may receive the protrusion 129 to fit and engage with the protrusion 129 in the lengthwise direction and restrict the first connector 50A from moving in the lengthwise direction with respect to the holder 120.
Next, benefits achievable from the fuser 8 according to the present embodiment will be described below.
When the fuser 8 is being assembled, first, the heater 110 may be placed on the supporting face 122A of the holder 122A. Next, the first wire spring 40A may be attached to the holder 120. In particular, the first engageable portion 42A and the second engageable portion 43A may be inserted in the attachable holes 125C, 126, respectively, and the facing portion 41A may be engaged with the grooves 127, 128. The second wire spring 40B may be attached to the holder 120 in the same manner. Thus, the heater 110 may be retained by the holder 120. Thereafter, the temperature sensors 10A, 10B may be attached to the heater 110 in an arrangement such that the temperature sensors 10A, 10B should contact the heater 110. While the temperature sensors 10A, 10B are being attached to the heater 110, the first and second wire springs 40A, 40B retain the heater 110. Therefore, the temperature sensors 10A, 10B may be attached to the holder 120 easily.
Next, the holder 120 may be installed in the heater unit 81. When the holder 120 is installed in the heater unit 81, as shown in
When the laser printer 1 is operating to print an image, the pressure roller 82 may rotate, and the belt 140 may be rotated by a friction force produced between the belt 140 and the pressure roller 82. By the friction produced between the belt 140 and the pressure roller 82, the belt 140 may be electrically charged. Meanwhile, the first and second wire springs 40A, 40B being grounded are located between the belt 140 and the first connector 50A and between the belt 140 and the second connector 50B, respectively. The charged electricity in the belt 140 may be discharged to the first and second wire springs 40A, 40B and removed from the belt 140. Therefore, the electricity charged in the belt 140 may be restrained from being discharged to the first or second connector 50A, 50B. Moreover, the belt 140 may reciprocate in the lengthwise direction while the laser printer 1 is operating; therefore, with the first and second wire springs 40A, 40B located on one and the other sides of the belt 140 in the lengthwise direction, the charged electricity may be removed from the belt 140 reliably.
According to the embodiment described above, benefits described below may be achievable.
With the first wire spring 40A retaining the heater 110 on the holder 120, the dimension of the heater 110 and the holder 120 in the lengthwise direction may be reduced.
The first wire spring 40A is in the arrangement, in which at least a part of the first wire spring 40A is located in the range, where the contacting area F of the holder 120 is located, in the lengthwise direction. Therefore, the dimension of the heater 110 and the holder 120 in the lengthwise direction may be effectively reduced.
The first wire spring 40A is grounded, and the shortest distance between the first wire spring 40A and the belt 140 is shorter than the shortest distance between the first connector 50A and the belt 140. Therefore, the electricity charged in the belt 140 may be restrained from being discharged to the first connector 50A but may be securely discharged through the first wire spring 40A.
The first wire spring 40A is located between the first connector 50A and the belt 140, and the shortest distance between the first wire spring 40A and the belt 140 is shorter than the shortest distance between the first wire spring 40A and the first connector 50A. Therefore, when the electricity charged in the belt 140 may be removed from the belt 140 through the first wire spring 40A reliably.
The holder 120 has the grooves 127, 128, with which the first facing portion 41A may engage. Therefore, the first wire spring 40A may be reliably placed at the correct position in the lengthwise direction with respect to the holder 120.
The holder 120 has the first stopper portion 125B and the second stopper portion 126B. Therefore, the first wire spring 40A may be securely restrained from falling off from the holder 120.
The first facing portion 41A extends straight in the widthwise direction. Therefore, the dimension of the heater 110 and the holder 120 in the lengthwise direction may be effectively reduced.
Although an example 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 first and second wire springs 40A, 40B and the first and second connectors 50A, 50B may not necessarily be located in the end areas of the heater 110 on the one and the other sides in the lengthwise direction, respectively. As shown in
For another example, as shown in
For another example, as shown in
For another example, as shown in
For another example, the first facing portion 41A of the first wire spring 40A may not necessarily extend straight across the heater 110 but may be in a curved form. For another example, as shown in
For another example, one or more elements in the embodiment and the examples described above may be optionally combined.
Number | Date | Country | Kind |
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2020-072045 | Apr 2020 | JP | national |