JP5957858B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device that thermally fixes a developer image transferred to a recording sheet.

  Conventionally, as a fixing device used in an electrophotographic image forming apparatus, a cylindrical fixing belt, a heater that is disposed inside the fixing belt and generates radiant heat, a nip member that is in sliding contact with the inner peripheral surface of the fixing belt, There has been known one provided with a reflecting member that is formed so as to cover the heater and reflects radiant heat toward the nip member (see, for example, Patent Document 1).

  Specifically, the reflecting member continuously contacts the nip member over substantially the entire width in the longitudinal direction.

JP 2011-95534 A

  However, in the technique as described above, the heat of the nip member escapes to the reflecting member, and it is difficult to efficiently heat the nip member.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of improving the heating efficiency of a nip member.

In order to achieve the above object, a fixing device according to the present invention is a fixing device for thermally fixing a developer image transferred to a recording sheet while moving the recording sheet in a predetermined direction. A cylindrical member, a heating element that is disposed inside the cylindrical member, emits radiant heat, a nip member that is in sliding contact with the inner peripheral surface of the cylindrical member, and that is in contact with the nip member and covers the heating element And a reflection member that reflects radiant heat toward the nip member, and a backup member that forms a nip with the tubular member interposed between the nip member and the nip member.
The nip member and the reflecting member are in intermittent contact with each other along the axial direction of the cylindrical member within the image forming width.

  According to the fixing device configured as described above, heat that escapes from the nip member to the reflecting member can be reduced within the image forming width, and thus the nip member can be efficiently heated. Moreover, although it is intermittent, since the nip member and the reflecting member are in contact with each other, it is possible to suppress leakage of radiant heat from between the nip member and the reflecting member.

  In the fixing device described above, it is desirable that the reflective member and the nip member are intermittently in contact with each other by forming a notch in a portion of the reflective member that contacts the nip member.

  According to the fixing device configured as described above, the rigidity of the nip member can be ensured by providing a cutout or the like in the nip member as compared with the configuration in which the reflecting member and the nip member are in intermittent contact.

  Moreover, when providing a notch part in a nip member as mentioned above, the notch part may be formed with two or more along the axial direction.

  And as above-mentioned, when providing a some notch part in a nip member, it is desirable that the sum total of the axial direction length of a some notch part is more than half of the full length of the axial direction of a reflection member.

  According to the fixing device configured as described above, the contact area between the nip member and the reflecting member can be further reduced, and thus the heating efficiency of the nip member can be further improved.

  Further, as described above, when a plurality of notches are provided in the nip member, the notch provided on the outermost side in the axial direction among the plurality of notches is a notch provided in a substantially central portion in the axial direction. It is desirable that the length in the axial direction is larger than the portion.

  As described above, the temperature distribution of the nip member can be made uniform by reducing the contact area between the nip member and the reflection member at the end portion in the axial direction of the nip member, which is difficult to rise in temperature when the fixing device is started up. . Further, since the contact area between the nip member and the reflecting member is large at the substantially central portion in the axial direction that is at a high temperature after use of the fixing device, heat can be radiated smoothly.

In the fixing device in which the notch portion is provided in the nip member, the reflecting member may be a plate-like member formed in a substantially U shape with the nip member side opened as viewed from the axial direction.
Moreover, this reflection member has a flange part which extends toward the outer side at the end part on the nip member side and contacts the nip member, and the aforementioned notch part may be formed in this flange part.

The fixing device in which the notch portion is provided in the flange portion of the reflection member described above may further include a stay that supports the side of the nip member opposite to the backup member.
In this case, it is desirable that the stay sandwich the flange portion of the reflecting member between the stay and the nip member.

  According to the fixing device configured as described above, the stay can also support the reflecting plate.

Further, the above-described stay may be formed in a substantially U shape with the nip member side opened as viewed from the axial direction.
The stay and the reflecting member described above may be made of metal.

The fixing device of the present invention for achieving the above-described object is a fixing device for thermally fixing a developer transferred to a recording sheet while moving the recording sheet in a predetermined direction. A cylindrical member, a heating element that is disposed inside the cylindrical member, emits radiant heat, a nip member that is in sliding contact with the inner peripheral surface of the cylindrical member, and that contacts the nip member and covers the heating element And a reflection member that reflects the radiant heat toward the nip member, and a backup member that forms a nip with the tubular member interposed between the nip member and the nip member.
At least one of the nip member and the reflection member has a contact portion that contacts the other of the nip member and the reflection member over the image formation width, and at least a part of the contact portion is notched within the image formation width. It is.

  Also with the fixing device configured as described above, heat that escapes from the nip member to the reflecting member can be reduced within the image forming width, so that the nip member can be efficiently heated. Moreover, although it is intermittent, since the nip member and the reflecting member are in contact with each other, it is possible to suppress leakage of radiant heat from between the nip member and the reflecting member.

  According to the present invention, since the nip member and the reflecting member are intermittently in contact with each other along the axial direction of the cylindrical member within the image forming width, it is possible to reduce heat that escapes from the nip member to the reflecting member. The nip member can be efficiently heated.

1 is a diagram illustrating a schematic configuration of a laser printer including a fixing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a fixing device. It is a perspective view of a nip board. It is a perspective view of a reflecting plate and a stay. It is XX sectional drawing of FIG. 4 which shows the contact part of a reflecting plate and a nip board. FIG. 10 is a schematic diagram illustrating a nip plate, a reflecting plate, and a stay in a fixing device according to a modification.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the laser printer 1 including the fixing device 100 of the present invention will be described, and then a detailed configuration of the fixing device 100 will be described.

  In the following description, the direction will be described with reference to the user who uses the laser printer 1. That is, the left side in FIG. 1 is “front”, the right side is “rear”, the front side is “right”, and the back side is “left”. Also, the vertical direction in FIG.

<Schematic configuration of laser printer>
As shown in FIG. 1, a laser printer 1 includes a main body housing 2 that feeds a sheet S as an example of a recording sheet, an exposure device 4, and a toner image (developer) on the sheet S. And the fixing device 100 for thermally fixing the toner image on the paper S.

  The paper feed unit 3 is provided at a lower portion in the main body housing 2 and mainly includes a paper feed tray 31, a paper pressing plate 32, and a paper feed mechanism 33. The paper S stored in the paper feed tray 31 is moved upward by the paper pressing plate 32 and supplied toward the process cartridge 5 (between the photosensitive drum 61 and the transfer roller 63) by the paper feed mechanism 33.

  The exposure apparatus 4 is disposed in the upper part of the main body housing 2 and includes a laser light emitting unit (not shown), a polygon mirror, a lens, a reflecting mirror, and the like that are not shown. In this exposure device 4, the surface of the photosensitive drum 61 is exposed by scanning the surface of the photosensitive drum 61 at high speed with laser light (see the chain line) based on the image data emitted from the laser light emitting unit.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. The process cartridge 5 includes a drum unit 6 and a developing unit 7.

  The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is configured to be detachably attached to the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner that contains toner (developer). The housing part 74 is mainly provided.

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby an image is formed on the photosensitive drum 61. An electrostatic latent image based on the data is formed. Further, the toner in the toner container 74 is supplied to the developing roller 71 via the supply roller 72 and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer of a certain thickness on the developing roller 71. It is carried on.

  The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Thereafter, the sheet S is conveyed between the photosensitive drum 61 and the transfer roller 63 so that the toner image on the photosensitive drum 61 is transferred onto the sheet S.

  The fixing device 100 is provided behind the process cartridge 5. The toner image (toner) transferred onto the paper S is thermally fixed onto the paper S by passing through the fixing device 100. The paper S on which the toner image has been thermally fixed is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

<Detailed configuration of fixing device>
As shown in FIG. 2, the fixing device 100 includes a fixing belt 110 as an example of a cylindrical member, a halogen lamp 120 as an example of a heating element, a nip plate 130 as an example of a nip member, and an example of a backup member. Are mainly provided with a pressure roller 140, a reflection plate 150 as an example of a reflection member, and a stay 160.

  The fixing belt 110 is an endless (cylindrical) belt having heat resistance and flexibility, and its rotation is guided by a guide member that is omitted from the reference numeral.

  The halogen lamp 120 is a heater that emits radiant heat to heat the toner on the sheet S by heating the nip plate 130 and the fixing belt 110. Inside the fixing belt 110, a predetermined amount is applied from the inner surfaces of the fixing belt 110 and the nip plate 130. It is arranged with an interval of.

  The nip plate 130 is a plate-like member that receives radiant heat from the halogen lamp 120, and is arranged inside the fixing belt 110 so that the lower surface thereof is in sliding contact with the inner peripheral surface of the cylindrical fixing belt 110. In the present embodiment, the nip plate 130 is formed, for example, by processing a metal plate such as an aluminum plate having a higher thermal conductivity than a steel stay 160 described later.

As shown in FIG. 3, the nip plate 130 has a base portion 131 and a bent portion 132.
The base portion 131 is a portion whose lower surface is in sliding contact with the inner peripheral surface of the fixing belt 110, and transmits heat from the halogen lamp 120 to the toner on the paper S via the fixing belt 110. The bent portion 132 is formed to extend upward from the front and rear ends of the base portion 131.

  As shown in FIG. 2, the pressure roller 140 is an elastically deformable member and is disposed below the nip plate 130. The pressure roller 140 is configured to form a nip N by sandwiching the fixing belt 110 with the nip plate 130 in an elastically deformed state. In the present embodiment, the nip plate 130 and the pressure roller 140 are configured to be in pressure contact with each other by being urged toward the other.

  The pressure roller 140 is configured to be rotationally driven by a driving force transmitted from a motor (not shown) provided in the main body housing 2, and to rotate with the fixing belt 110 (or the paper S). The fixing belt 110 is driven to rotate by the frictional force. Thus, the sheet S on which the toner image is transferred is conveyed between the pressure roller 140 and the heated fixing belt 110 in the front-rear direction (predetermined direction), whereby the toner image (toner) is thermally fixed. .

  The reflection plate 150 is a member that reflects the radiant heat from the halogen lamp 120 toward the nip plate 130 (the upper surface of the nip plate 130), and is disposed at a predetermined interval from the halogen lamp 120 so as to cover the halogen lamp 120. Has been.

  The reflector 150 is a metal plate having a high infrared and far-infrared reflectance, such as an aluminum plate, bent in a substantially U shape when viewed from the axial direction of the fixing belt 110 (hereinafter simply referred to as “axial direction”). Is formed. More specifically, as shown in FIG. 4, the reflecting plate 150 includes a reflecting portion 151 having a curved shape (substantially U shape in cross section) and a front-rear direction from both ends of the reflecting portion 151 on the lower side (nip plate 130 side). It mainly has a flange portion 152 extending outward.

  The reflecting portion 151 can collect the radiant heat from the halogen lamp 120 on the nip plate 130. Thereby, the radiant heat from the halogen lamp 120 can be used efficiently, and the nip plate 130 and the fixing belt 110 can be quickly heated.

  The flange portion 152 is an example of a contact portion that is a portion that contacts the nip plate 130. Specifically, the front flange portion 152 is in contact with the upper end surface of the front bent portion 132 of the nip plate 130, and the rear flange portion 152 is in contact with the upper surface of the base portion 131 of the nip plate 130 ( (See FIG. 2).

  A plurality of notches 153 are formed in the rear flange portion 152 along the axial direction within the image forming width W. As a result, as shown in FIG. 5, the nip plate 130 and the flange portion 152 on the rear side of the reflecting plate 150 are in intermittent contact with each other along the axial direction within the image forming width W.

  The plurality of cutout portions 153 will be described in detail. The cutout portion 153 is cut out from the rear end of the flange portion 152 to an intermediate portion (a portion behind the fold portion between the reflection portion 151 and the flange portion 152). Is formed. Thus, by forming the cutout portion 153 so as not to reach the crease portion or the reflection portion 151, the radiant heat is less likely to leak from the cutout portion 153.

  The plurality of notches 153 are provided in the flange portion 152 such that the total length in the axial direction of the plurality of notches 153 is more than half of the total axial length of the reflector 150. (See FIG. 4).

  Further, among the plurality of cutout portions 153, the cutout portion 153A provided on the outermost side in the axial direction has a larger length in the axial direction than the cutout portion 153B disposed at a substantially central portion in the axial direction. It has become.

  Specifically, as shown in FIG. 4, a notch 153A provided in a predetermined range A at both ends in the axial direction of the rear flange portion 152 has a predetermined range B (predetermined in a substantially central portion in the axial direction). The length in the axial direction of the range A and the predetermined range B is the same.) The cutout 153B is larger than the cutout 153B. Accordingly, the contact area between the flange portion 152 and the nip plate 130 in the predetermined range A is smaller than the contact area between the flange portion 152 and the nip plate 130 in the predetermined range B.

  As shown in FIG. 2, the stay 160 is a member that supports both ends of the nip plate 130 in the front-rear direction from the side opposite to the pressure roller 140, and the halogen lamp 120 and the reflection plate 150 are placed inside the fixing belt 110. It is arranged to cover. The stay 160 has a relatively high rigidity, for example, a metal plate such as a steel plate having an opening on the nip plate 130 side and a shape along the reflecting plate 150 (reflecting portion 151) (approximately U when viewed from the axial direction). It is formed by bending in a shape).

  More specifically, as shown in FIG. 4, the stay 160 has an upper wall 161 and a front wall 162 and a rear wall 163 that extend downward from the front and rear ends of the upper wall 161. The lower end portion of the front wall 162 supports the front end portion of the nip plate 130 from above via the flange portion 152 on the front side of the reflecting plate 150, and the lower end portion of the rear wall 163 is the rear side of the reflecting plate 150. The rear end of the nip plate 130 is supported from above via the flange portion 152. That is, the stay 160 sandwiches the reflection plate 150 between the nip plate 130 and the stay 160 can hold both the reflection plate 150 and the nip plate 130.

  Such a stay 160 supports the nip plate 130 by receiving the force applied to the nip plate 130 from below (the pressure roller 140 side).

According to the above, the following effects can be obtained in the present embodiment.
Since the nip plate 130 and the reflecting plate 150 are in intermittent contact with each other along the axial direction within the image forming width W, heat escapes from the nip plate 130 to the reflecting plate 150 within the image forming width W. Can be reduced. Thereby, the nip plate 130 can be efficiently heated. Further, although intermittently, since the nip portion plate 130 and the reflecting plate 150 are in contact with each other, it is possible to suppress leakage of radiant heat from between the nip plate 130 and the reflecting plate 150.

  Since the notch 153 is formed in the flange portion 152 on the front side of the reflecting plate 150, the nip plate 130 and the reflecting plate 150 are configured to contact intermittently. The rigidity of the nip plate 130 can be ensured as compared with the case where the notch is provided.

  Further, the total axial length of the plurality of cutouts 153 formed in the flange portion 152 of the reflector 150 is more than half of the total length of the flange 152. Therefore, the contact area between the nip plate 130 and the reflector 150 is further increased. The heating efficiency of the nip plate 130 can be further improved.

  Of the plurality of cutout portions 153, the cutout portion 153A provided on the outermost side in the axial direction has a larger axial length than the cutout portion 153B provided in the substantially central portion in the axial direction. It has become. As described above, the temperature distribution of the nip plate 130 is made uniform by reducing the contact area between the nip plate 130 and the reflection plate 150 at the axial end portion of the nip plate 130 where the temperature hardly rises when the fixing device 100 is started up. Can be. In addition, since the contact area between the nip plate 130 and the reflecting plate 150 is large in the central portion in the axial direction that is at a high temperature after the fixing device 100 is used, heat dissipation can be performed smoothly.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the said embodiment, it was set as the structure which makes the nip plate 130 and the reflecting plate 150 contact intermittently along an axial direction by providing the some notch part 153 in the flange part 152 which contacts the nip plate 130 of the reflecting plate 150. FIG. However, the present invention is not limited to this. For example, the nip plate may be processed and the nip plate and the reflection plate may be intermittently contacted along the axial direction.

  Specifically, this form will be described. As shown in FIG. 6, the portion of the nip plate 230 that comes into contact with the flange portion 252 of the reflection plate 250 has a reflection plate 250 side formed by deforming the nip plate 230. A plurality of protruding protrusions 231 are provided along the axial direction. Thereby, the nip plate 230 and the reflecting plate 250 are intermittently contacted along the axial direction.

  Moreover, a notch part and a convex part may be provided in both the flange part of a nip plate and a reflecting plate, and you may contact a nip plate and a reflecting plate intermittently along an axial direction.

  In the embodiment, the plurality of notches 153 are provided in the flange 152 of the reflector 150. However, the present invention is not limited to this, and one notch is provided in the flange of the reflector. It may be.

  Further, in the embodiment, the cutout portion 153 is provided only in the flange portion 152 on the rear side of the reflector 150, but the present invention is not limited to this, and the cutout portion is also provided in the front flange portion 152. Also good.

In the above embodiment, the halogen lamp 120 is exemplified as the heating element, but the present invention is not limited to this, and may be a carbon heater, for example.

  In the embodiment, the plate-shaped nip plate 130 is exemplified as the nip member. However, the present invention is not limited to this, and for example, a thick member that is not plate-shaped may be employed.

  In the embodiment, the pressure roller 140 is exemplified as the backup member. However, the present invention is not limited to this, and may be, for example, a belt-like pressure member.

  In the embodiment, the paper S such as plain paper or postcard is exemplified as the recording sheet. However, the present invention is not limited to this, and may be, for example, an OHP sheet.

DESCRIPTION OF SYMBOLS 1 Laser printer 100 Fixing device 110 Fixing belt 120 Halogen lamp 130 Nip plate 140 Pressure roller 150 Reflecting plate 152 Flange part 153 Notch part 160 Stay N nip S Paper W Image formation width

Claims (11)

A fixing device for thermally fixing a developer image transferred to a recording sheet while moving the recording sheet in a predetermined direction,
A flexible tubular member;
A heating element that is disposed inside the cylindrical member and emits radiant heat; and
A nip member slidably in contact with the inner peripheral surface of the tubular member;
A reflective member that contacts the nip member and that covers the heating element and reflects the radiant heat toward the nip member;
A backup member that forms a nip with the tubular member sandwiched between the nip member, and
Since the cutout portion is formed in the portion of the reflecting member that contacts the nip member, the reflecting member and the nip member have one cross section along the axial direction of the cylindrical member within the image forming width. In intermittent contact,
A plurality of the cutout portions are formed along the axial direction, and the total length of the cutout portions in the axial direction is not less than half of the total length of the reflective member in the axial direction. Fixing device to do. A fixing device for thermally fixing a developer image transferred to a recording sheet while moving the recording sheet in a predetermined direction,
A flexible tubular member;
A heating element that is disposed inside the cylindrical member and emits radiant heat; and
A nip member slidably in contact with the inner peripheral surface of the tubular member;
A reflective member that contacts the nip member and that covers the heating element and reflects the radiant heat toward the nip member;
A backup member that forms a nip with the tubular member sandwiched between the nip member, and
Since the cutout portion is formed in the portion of the reflecting member that contacts the nip member, the reflecting member and the nip member have one cross section along the axial direction of the cylindrical member within the image forming width. In intermittent contact,
A plurality of the cutout portions are formed along the axial direction, and the cutout portion provided on the outermost side in the axial direction among the plurality of cutout portions is provided at a substantially central portion in the axial direction. The fixing device is characterized in that the length in the axial direction is larger than the cutout portion. A fixing device for thermally fixing a developer image transferred to a recording sheet while moving the recording sheet in a predetermined direction,
A flexible tubular member;
A heating element that is disposed inside the cylindrical member and emits radiant heat; and
A nip member slidably in contact with the inner peripheral surface of the tubular member;
A reflective member that contacts the nip member and that covers the heating element and reflects the radiant heat toward the nip member;
A backup member that forms a nip with the tubular member sandwiched between the nip member, and
Since the cutout portion is formed in the portion of the reflecting member that contacts the nip member, the reflecting member and the nip member have one cross section along the axial direction of the cylindrical member within the image forming width. In intermittent contact,
The reflection member, when viewed from the axial direction, extends outward from a reflection portion formed in a substantially U shape with the nip member side open, and an end portion of the reflection portion on the nip member side, A flange portion that contacts the nip member,
The fixing device according to claim 1, wherein the notch portion is formed in the flange portion, and is formed from an outer end portion of the flange portion to an intermediate portion toward the end portion of the reflecting portion. The reflection member, when viewed from the axial direction, extends outward from a reflection portion formed in a substantially U shape with the nip member side open, and an end portion of the reflection portion on the nip member side, A flange portion that contacts the nip member,
The said notch part is formed in the said flange part, and is formed from the outer edge part of the said flange part to the intermediate part toward the said edge part of the said reflection part, The Claim 1 or Claim 2 characterized by the above-mentioned. The fixing device according to 1.   3. The fixing device according to claim 1, wherein the reflection member is a plate-like member formed in a substantially U shape with the nip member side open as viewed from the axial direction. . The reflecting member has a flange portion that extends outward at an end portion on the nip member side and contacts the nip member;
The fixing device according to claim 5, wherein the cutout portion is formed in the flange portion. A stay that supports a side of the nip member opposite to the backup member;
The fixing device according to claim 3, wherein the stay sandwiches the flange portion of the reflection member between the stay and the nip member.   The fixing device according to claim 7, wherein the stay is formed in a substantially U shape with the nip member side open as viewed from the axial direction.   The fixing device according to claim 7, wherein the stay is made of metal.   The fixing device according to claim 1, wherein the reflecting member is made of metal. The fixing device according to claim 1, wherein the nip member is made of metal.

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