JP4880357B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device for fixing a toner image transferred onto a sheet to the sheet.

  2. Description of the Related Art Conventionally, a fixing device that is used in an image forming apparatus such as a printer or a copying machine and fixes a toner image transferred onto a sheet to the sheet is known. In such a fixing device, an elastic layer (rubber layer) is provided on the pressure (press) roller and the fixing (heat) roller, and the sheet is fed from the peripheral surface of the fixing roller by the nip shape between the pressure roller and the fixing roller. The means of separating has been used.

  However, when an elastic layer is provided on the fixing roller, problems such as a decrease in temperature followability during continuous paper feeding and an increase in warm-up time occur due to the low thermal conductivity of the elastic layer. Therefore, it is difficult to sufficiently cope with the recent energy saving trend. Further, a technique for fixing a toner image on a sheet using a belt has been proposed and commercialized, but there is a disadvantage that the structure is complicated and the cost increases.

  On the other hand, there is known a fixing device using a so-called hard roller as a fixing roller, which is formed by coating the surface of an aluminum or iron cored bar with a fluororesin coating or a tube. It is possible to sufficiently shorten the warm-up time due to the high thermal conductivity, and it is possible to configure the fixing device at a low cost.

  However, when the above-described fixing roller (hard roller) is used, a large adhesion force is generated between the fixing roller in which a large amount of molten toner intervenes and the sheet, so that the separation claw is brought into contact with the fixing roller. It is necessary to use means for forcibly separating the sheet from the peripheral surface of the fixing roller. For this reason, there has been a disadvantage that the fixing roller is worn when repeatedly used.

Therefore, in order to suppress wear of the fixing roller due to the separation claw, a technique for reducing the contact pressure of the separation claw to the fixing roller by increasing the width of the tip of the separation claw has been proposed (for example, Patent Document 1). reference). This patent document 1 discloses a fixing device in which a separation claw that rotates around one axial direction (axial direction of the fixing roller) is configured to contact a peripheral surface of the fixing roller using a spring. Yes.
JP 2004-157481 A

  However, in the contact method of the separation claw to the fixing roller as disclosed in Patent Document 1, the tip of the separation claw contacts the peripheral surface of the fixing roller in a single-contact state due to a dimensional error of a component member or the like. In this case, since the contact portion between the two becomes almost point contact, the contact pressure of the separation claw with respect to the fixing roller is concentrated on the contact portion, and the effect of widening the width of the tip of the separation claw cannot be obtained sufficiently. As a result, it is difficult to sufficiently suppress the wear of the fixing roller. As a result, streaks are formed on the image due to wear marks on the fixing roller, and there is a problem that remarkable image deterioration occurs particularly in a color type image forming apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of suppressing the occurrence of image deterioration.

In order to achieve the above object, a fixing device according to claim 1 of the present invention includes a fixing roller for fixing a toner image transferred onto a sheet to the sheet, and a separating unit for separating the sheet from the fixing roller. In the fixing device, the separation unit is provided on the support member, a separation claw that contacts the circumferential surface of the fixing roller to separate the paper from the fixing roller, a support member that supports the separation claw , and the support member are looking contains a housing for mounting said support member and biasing member for urging the peripheral surface of the fixing roller the separating claw so that the separating claw presses the fixing roller, the separation pawl A swinging fulcrum part that functions as a fulcrum in a swinging state, and a tip claw part that is provided at a predetermined interval from the swinging fulcrum part and contacts the peripheral surface of the fixing roller. The force member The portion between the swinging fulcrum portion of the claw and the tip claw portion is biased, the swinging fulcrum portion of the separation claw contacts the housing by the biasing force of the biasing member, and the swinging fulcrum portion is The housing includes a concave fulcrum receiving portion capable of holding the oscillating fulcrum portion, and the support member oscillates the separation claw via the urging member. The fulcrum portion is supported as a fulcrum so as to be swingable around a multi-axis direction .

In the fixing device according to the first aspect, as described above, the separation claw urged toward the fixing roller is used as a fulcrum with the substantially spherical swinging fulcrum portion of the separation claw via the urging member. By being configured to be swingable around multiple axes , even if the separation claw comes into contact with the peripheral surface of the fixing roller due to, for example, a dimensional error of a component member, the separation claw is a biasing member. According to this urging force, the piece can be quickly swung in the direction of correcting the one-piece contact, so that the separation claw can always be brought into contact (close contact) with the peripheral surface of the fixing roller with uniform pressure. As a result, the contact area between the separation claw and the peripheral surface of the fixing roller can be increased, so that the contact pressure per unit area of the separation claw with respect to the fixing roller can be reduced.

In addition, since the separation claw is supported by the support member via the urging member , the separation claw can be supported by the urging member while being urged toward the fixing roller by the urging member. Since the urging member absorbs the external force acting on the separation claw, the separation claw can be easily swung according to the external force.

The separation claw includes a swing fulcrum portion having a fulcrum function and a tip claw portion provided at a predetermined interval from the swing fulcrum portion, and the separation claw swing tip portion and the tip claw portion. By urging the portion between the urging member and the urging member, the front end claw portion contacting the peripheral surface of the fixing roller can be easily oscillated with the oscillating fulcrum portion as a fulcrum.

Further, since the swinging fulcrum portion of the separation claw is brought into contact with the housing by the urging force of the urging member, the swinging fulcrum portion can be reliably functioned as a fulcrum. The tip claw can be freely swung around the multi-axis direction by applying the urging force.

Also, by holding the substantially spherical rocking fulcrum part with the concave fulcrum receiving part formed in the housing, the rocking fulcrum part can be easily rotated (pivoted). The tip claw can be easily swung freely around the multi-axis direction .

In the fixing device according to claim 1, it is preferable that the fulcrum receiving portion is formed in a concave shape that is gradually widened from the bottom portion toward the opening portion (claim 2 ).

  If comprised in this way, a fulcrum receiving part will have a side peripheral wall inclined so that it may spread gradually toward the opening part from the bottom part. Accordingly, it is possible to keep the force that always places the substantially spherical rocking fulcrum part at a predetermined position in the middle of the fulcrum receiving part on the rocking fulcrum part. Accordingly, the swing fulcrum portion can be rotatably held at a predetermined position, and thus the swing fulcrum portion can be stably rotated (pivot motion).

In the fixing device according to claim 1 or 2 , preferably, the biasing member is disposed at a symmetrical position with respect to the swing fulcrum and along the axial direction of the fixing roller. A pair of coil springs is included (claim 3 ).

If comprised in this way, the both ends along the axial direction of a fixing roller of the front-end | tip nail | claw part which can freely rock | fluctuate around a multi-axis direction on a rocking | fulcrum fulcrum part are each on the surrounding surface of a fixing roller. Since two independent urging forces can be applied to the separation claw from a pair of coil springs in a balanced manner so that they come into contact with each other, even when the urging force is weak, the separation claw contacts the peripheral surface of the fixing roller in a single contact state. There is nothing to do. Thereby, even if the tip claw portion is relatively wide, the separation claw can be brought into close contact with the peripheral surface of the fixing roller with a weak pressing force.

  According to the fixing device of the present invention, the contact pressure per unit area of the separation claw with respect to the fixing roller can be reduced by always bringing the separation claw into close contact with the circumferential surface of the fixing roller. Wear due to contact with the claws can be sufficiently suppressed. As a result, it is possible to sufficiently suppress the occurrence of image degradation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional front view showing an overall configuration of a printer including a fixing device according to an embodiment of the present invention, and FIG. 2 is a front view for explaining the configuration of the fixing device shown in FIG. is there. 3 to 7 are diagrams for explaining the configuration of the separation mechanism of the fixing device shown in FIG. First, an overall configuration of a printer 1 including a fixing device 20 according to an embodiment of the present invention will be described with reference to FIG.

  In the printer 1, as shown in FIG. 1, a developing device 3 is provided in a printer main body 2 for each of cyan, magenta, yellow, and black colors. Each developing device 3 is provided with a photosensitive drum 4 made of a-Si (amorphous silicon) or the like and rotates in the direction of the arrow in the drawing. The photosensitive drum 4 is uniformly charged by a charger 5, and LED light based on document image data input from an external PC (personal computer) or the like is sent from the exposure device (LED print head unit or the like) 6 to the photosensitive drum 4. An electrostatic latent image is formed by irradiating the surface of the toner, and toner adheres to the electrostatic latent image to form a toner image. The toner is supplied from the toner supply containers 7C, 7M, 7Y, and 7B. A conveyor belt 8 is disposed below the photosensitive drums 4 for the respective colors. The conveying belt 8 is pressed against each photosensitive drum 4 by the transfer roller 9, and is driven according to a driving roller 10 that is rotationally driven by a motor or the like (not shown) and a conveying belt 8 that is endlessly rotated by the driving roller 10. The photosensitive drum 4 is rotated in the forward direction by the rotating driven roller 11.

  Then, the sheet P is conveyed from the sheet feeding unit 12 to the conveying belt 8 via the sheet conveying path 13, and the image transfer operation and the sheet feeding operation by the photosensitive drums 4 and the transfer rollers 9 by the registration roller pair 14. And the timing is adjusted. After the timing adjustment, the registration roller pair 14 is driven to rotate, and the paper P is conveyed between the photosensitive drum 4 and the conveying belt 8. While the paper P is conveyed between the photosensitive drums 4 and the conveyor belt 8, the toner images of the respective colors on the surfaces of the photosensitive drums 4 are successively transferred to the paper P. The paper P on which the toner image has been transferred by all the photosensitive drums 4 is conveyed to the fixing device 20, where the toner image is fixed, and a color image is formed. The paper P that has passed through the fixing device 20 is sent to the paper transport path 15 and discharged to the paper discharge unit 16. Each of the photosensitive drums 4 is provided with a cleaning device 17 that removes residual toner and the like on the photosensitive drum 4.

  Next, the configuration of the fixing device 20 will be described in detail with reference to FIGS.

  As shown in FIG. 2, the fixing device 20 includes a fixing (heat) roller 41 capable of generating heat in a housing 30 as a main body of the device, and a lower portion of the fixing roller 41 so that the peripheral surface of the fixing roller 41 faces each other. And a pressurizing (pressing) roller 42. Then, the paper P after the transfer process passes through a nip region between the fixing roller 41 that rotates clockwise and the pressure roller 42 that rotates counterclockwise, and thereby heat is generated from the fixing roller 41. The fixing process is performed after being applied.

  The fixing roller 41 includes an outer cylinder 41a formed by coating a peripheral surface of a metal cylinder with a predetermined material, and a heat source (not shown) including, for example, a halogen lamp built in the outer cylinder 41a. )). The outer cylinder 41a has an annular gear (not shown) fixed to one end thereof, and the rotation of a motor (not shown) installed at a suitable position outside the housing 30 is rotated via the gear mechanism or the like. By being transmitted to the gear, the outer cylinder 41a is configured to be driven and rotated around the axis.

  The pressure roller 42 includes a cylindrical pressure roller main body 42a and a pressure roller shaft 42b that is disposed concentrically with the pressure roller main body 42a and penetrates the end wall of the pressure roller main body 42a. I have. The pressure roller 42 is configured to rotate in accordance with the driving rotation of the fixing roller 41 when pressed against the peripheral surface of the outer cylinder 41a of the fixing roller 41 in the nip region.

  Further, the fixing device 20 includes a plurality of (four in the present embodiment) separation mechanisms 50 which are attached at appropriate positions in the housing 30 at a predetermined interval in the axial direction of the fixing roller 41. A discharge roller pair 43 for directing the sheet P after the fixing process to the sheet conveyance path 15 (see FIG. 1) is provided on the downstream side of the sheet 50 (left side in FIG. 2). The separation mechanism 50 is an example of the “separation means” in the present invention.

  In the fixing device 20, the fixing roller 41 and the pressure roller 42 are used until the front end of the sheet P passes through the nip region between the fixing roller 41 and the pressure roller 42 and reaches the discharge roller pair 43. The sheet P is transported by the time between the fixing roller 41 and the pressure roller 42 and the discharge roller until the rear end of the sheet P passes through the nip region after the front end of the sheet P reaches the discharge roller pair 43. The pair 43 and the pair 43 are configured to carry the paper P while being synchronized with each other. In addition, after the trailing edge of the paper P passes through the nip region, the paper P is transported only by the discharge roller pair 43.

  The separation mechanism 50 has a function of separating the paper P to be wound around the peripheral surface of the fixing roller 41 from the peripheral surface of the fixing roller 41, and includes a separation claw unit 60, a support member 70, and a pair of compression members. A coil spring 80 (see FIG. 3) is provided. The separation claw unit 60 is an example of the “separation claw” in the present invention, and the compression coil spring 80 is an example of the “coil spring” and the “biasing member” in the present invention.

  The separation claw unit 60 includes a holder member 61, a claw member 62 that is substantially L-shaped when viewed from the front, and a pair of roller members 63 (see FIG. 4).

  The holder member 61 holds the claw member 62 in a fixed manner, and is disposed in a non-contact state with the fixing roller 41 as shown in FIG. It is configured in an inclusive shape. The holder member 61 includes a male holder 64 having a male structure and a female holder 65 having a female structure.

  As shown in FIGS. 5 to 7, the male holder 64 is formed on the opposing surface of the side plate 64 a that is horizontally long when viewed from the front, the spring seat portion 64 b formed on the upper side of the side plate 64 a, and the female holder 65 of the side plate 64 a. The formed holder width restricting portion 64c, the press-fitting hole 64d formed at a position corresponding to the movement restricting portion 62c of the claw member 62 described later of the side plate 64a, and the opposing surface of the female holder 65 of the side plate 64a are formed. It has a support shaft portion 64e and a guide portion 64f (see FIG. 6B) provided at a lower portion on the upstream side of the conveyance path of the side plate 64a.

  The female holder 65 is formed at a position corresponding to the side plate 65a that is horizontally long when viewed from the front, the spring seat 65b formed on the top of the side plate 65a, and the holder width restricting portion 64c of the male holder 64 of the side plate 65a. An insertion hole 65c formed, a press-fitting hole 65d formed at a position corresponding to the movement restricting portion 62c of the claw member 62 of the side plate 65a, and a support shaft portion 65e formed on the opposing surface of the male holder 64 of the side plate 65a. And a guide portion 65f (see FIG. 6B) provided at a lower portion of the side plate 65a on the upstream side of the conveyance path.

  The spring seats 64b and 65b are for contacting the upper end of the compression coil spring 80, and the lower ends of the spring seats 64b and 65b are engaged with the upper end of the compression coil spring 80, respectively. Bosses 64g and 65g for stopping are formed. The spring seats 64b and 65b are positioned approximately in the middle of a swinging fulcrum 62a and a tip claw 62b of a claw member 62 described later when the separation claw unit 60 is assembled.

  The holder width restricting portion 64 c is provided to restrict the distance between the holders 64 and 65 to restrict the width of the holder member 61. That is, the holder width restricting portion 64c includes a columnar base portion 64h and an insertion portion 64i inserted into the insertion hole 65c of the female holder 65 and having a smaller diameter than the base portion 64h. When the base portion 64h abuts on the side plate 65a of the female holder 65, the side plates 64a and 65a are held in a state of being spaced apart from the base portion 64h in the axial direction.

  The support shaft portions 64e and 65e are arranged so as to face each other, and are configured to hold the roller member 63 rotatably. These support shaft portions 64e and 65e protrude from the side plates 64a and 65a in such a protruding amount that they are not in contact with the claw member 62.

  The guide portions 64 f and 65 f are provided to smoothly guide the front end of the paper P to the roller member 63 in the conveyance path of the paper P between the claw member 62 and the roller member 63.

  The claw member 62 comes into contact with the peripheral surface of the fixing roller 41, and has a swinging fulcrum part 62a, a tip claw part 62b, and a pair of movement restricting parts 62c.

  The swinging fulcrum portion 62a is formed in a substantially spherical shape, and when the separation mechanism 50 is attached to the housing 30, a concave fulcrum receiving portion 31 formed on the housing 30 (see FIGS. 5 to 7). It is held so that it can pivot. The fulcrum receiving portion 31 has a substantially square horizontal cross section, and is formed so as to gradually become wider from the bottom toward the opening. As for the swing fulcrum 62a, the tip claw 62b of the separation claw unit 60 described below can freely move in multiple directions (oscillates around multiple axes: see arrows α, β, γ in FIGS. 5 to 7). It functions as a fulcrum when doing. The swing fulcrum portion 62a may be formed in, for example, a conical shape other than the substantially spherical shape.

  The tip claw portion 62b is provided at a predetermined interval from the swinging fulcrum portion 62a, has a flat plate shape, and is formed so that the tip thereof has an acute angle in the longitudinal section. As described above, the tip claw portion 62b contacts the peripheral surface of the fixing roller 41 in a state in which the separation mechanism 50 is attached to the housing 30 and can swing around the multi-axis direction with the swing fulcrum portion 62a as a fulcrum. It is supposed to be.

  The movement restricting portion 62c is for fixing the claw member 62 to the holder member 61, and includes a base portion 62d having a rectangular cross section and a press-fit portion 62e having a cross section that is slightly smaller than the base portion 62d. The base 62d abuts against the side plates 64a and 65a of the holders 64 and 65, so that the movement of the claw member 62 between the holders 64 and 65 is restricted. Thus, the claw member 62 whose position is restricted by the base 62d of the movement restricting part 62c is located approximately in the middle between the side plates 64a and 65a.

  As described above, the claw member 62 is positioned and disposed so as to be positioned substantially in the middle of the side plates 64 a and 65 a of the holders 64 and 65, and the tip claw portion 62 b is transported of the holder member 61. It arrange | positions so that it may protrude toward the exterior from the edge part of a path | route upstream. Further, the tip claw 62b abuts against the peripheral surface of the fixing roller 41 by a biasing force of the pair of compression coil springs 80 at a predetermined distance from an end (nip region outlet) on the downstream side in the conveyance direction of the nip region. ing.

  The pair of roller members 63 are rotatably held by the holder member 61 by inserting the support shaft portions 64e and 65e into the respective shaft holes 63a, and sandwich the claw member 62 between the side plates 64a and 65a. It is arranged. As shown in FIG. 4, the roller member 63 is detachable from the claw member 62 and has a predetermined play in the protruding direction of the support shaft portions 64e and 65e. Is retained. In addition, the roller member 63 is configured such that, in a state where the roller member 63 is held by the holder member 61, a part of the peripheral surface is exposed from the lower part of the holder member 61 to the outside.

  The support member 70 has a function of supporting the separation claw unit 60 so as to be swingable around the multi-axis direction so that the claw member 62 of the separation claw unit 60 is always in close contact with the peripheral surface of the fixing roller 41. , A notch 71, a pair of hooks 72, a pair of positioning projections 73, and a pair of spring seats 74.

  The cutout portion 71 is formed by cutting out an appropriate portion of the support member 70 into a rectangular shape in plan view so that the support member 70 does not interfere with the claw member 62 of the separation claw unit 60.

  The hook portion 72 is provided to fix the support member 70 to the housing 30 by being inserted into and engaged with a hook engagement hole 32 formed in the housing 30.

  The positioning projections 73 are inserted into the positioning recesses 33 formed in the housing 30 so as to function as positioning when the support member 70 is attached to the housing 30.

  The spring seat 74 is for contacting the lower end of the compression coil spring 80, and the upper surface of the spring seat 74 is for locking the lower end of the compression coil spring 80. A boss 75 is formed.

  The pair of compression coil springs 80 are arranged symmetrically with respect to the swing fulcrum 62a (see FIGS. 5 and 7) and along the axial direction of the fixing roller 41 (see FIG. 3). As described above, it is installed between the spring seat portion 74 of the support member 70 and the spring seat portion 64b (65b) of the separation claw unit 60, and is separated so that the claw member 62 presses the fixing roller 41. The claw unit 60 is configured to be supported while being urged toward the peripheral surface of the fixing roller 41. When the support member 70 is attached to the housing 30, the pair of compression coil springs 80 brings the separation claw unit 60 into contact with both the housing 30 and the peripheral surface of the fixing roller 41 by the urging force of the compression coil spring 80. Is compressed.

  In the separation mechanism 50 configured as described above, both ends (upper and lower ends in FIG. 4) of the front end claw portion 62b of the claw member 62 of the separation claw unit 60 are peripheral surfaces of the fixing roller 41 by the urging force of the pair of compression coil springs 80. For example, when the separation claw unit 60 comes into contact with the peripheral surface of the fixing roller 41 in a single-contact state, the mortar shape of the housing 30 is applied while following the urging force of the pair of compression coil springs 80. The fulcrum fulcrum 62a, which is supported by the fulcrum receiving part 31 so as to be pivotable, swings around a multi-axis direction (see arrows α, β, γ in FIGS. 5 to 7). Yes.

  In the present embodiment, as described above, the separation claw unit 60 biased toward the fixing roller 41 is configured to be swingable around the multi-axis direction, for example, due to a dimensional error of a component member. Even if the separation claw unit 60 comes into contact with the peripheral surface of the fixing roller 41 in a one-sided state, the separation claw unit 60 can quickly swing in a direction to correct the one-sided contact according to the urging force of the compression coil spring 80. Therefore, the separation claw unit 60 can always be brought into contact (close contact) with the peripheral surface of the fixing roller 41 with uniform pressure. For this reason, since the contact area between the separation claw unit 60 and the peripheral surface of the fixing roller 41 can be increased, the contact pressure per unit area of the separation claw unit 60 with respect to the fixing roller 41 can be reduced. Thereby, it is possible to sufficiently suppress the circumferential surface of the fixing roller 41 from being worn by contact with the separation claw unit 60, and thus it is possible to sufficiently suppress the occurrence of image deterioration.

  In the present embodiment, as described above, the separation claw unit 60 is supported by the support member 70 via the compression coil spring 80, so that the separation claw unit 60 is directed toward the fixing roller 41 by the compression coil spring 80. Since the compression coil spring 80 can be supported by the compression coil spring 80 while being urged, the separation coil unit 60 can be easily expanded or contracted so as to absorb the external force acting on the separation claw unit 80. It can be swung.

  Further, in the present embodiment, as described above, the claw member 62 of the separation claw unit 60 includes the swing fulcrum portion 62a having a fulcrum function and the tip claw provided at a predetermined interval from the swing fulcrum portion 62a. And a portion (spring seats 64b and 65b of the holders 64 and 65) between the swinging fulcrum 62a and the tip claw 62b of the claw member 62 by a pair of compression coil springs 80, respectively. By urging, the tip claw portion 62b contacting the peripheral surface of the fixing roller 41 can be easily swung with the swing fulcrum portion 62a as a fulcrum.

  In the present embodiment, as described above, the swinging fulcrum part 62a of the separation claw unit 60 is brought into contact with the housing 30 by the urging force of the compression coil spring 80, thereby using the swinging fulcrum part 62a as a fulcrum. Since it can function reliably, the urging force of the compression coil spring 80 is applied to the tip claw portion 62b of the claw member 62, and the tip claw portion 62b can be swung around the multi-axis direction.

  Further, in the present embodiment, as described above, by holding the substantially spherical rocking fulcrum part 62a by the concave fulcrum receiving part 31 formed in the housing 30, the rocking fulcrum part 62a can be easily pivoted. Since it can be made to move, the front-end | tip nail | claw part 62b of the nail | claw member 62 of the isolation | separation nail | claw unit 60 can be rock | fluctuated around a multi-axis direction easily.

  Further, in the present embodiment, as described above, the fulcrum receiving portion 31 has a substantially square horizontal cross section and is formed so as to gradually become wider from the bottom toward the opening. 31 has a side wall 31a that is inclined so as to gradually spread from the bottom toward the opening, so that the substantially spherical rocking fulcrum 62a is positioned at a predetermined position in the middle of the fulcrum receiving part 31. It is possible to keep the force that is always located (see FIG. 3) acting on the swing fulcrum 62a. Accordingly, the swing fulcrum portion 62a can be rotatably held at a predetermined position, and thus the swing fulcrum portion 62a can be stably rotated (pivoted).

Further, in the present embodiment, as described above, the pair of compression coil springs 80 are disposed at symmetrical positions with respect to the swing fulcrum 62a and along the axial direction of the fixing roller 41. A pair of compression coil springs are provided so that both ends (upper and lower ends in FIG. 4) of the tip claw 62b that can freely swing around the multi-axis direction are brought into contact with the peripheral surface of the fixing roller 41 with the swing fulcrum 62a as a fulcrum. Since two independent urging forces can be applied from 80 to the separation claw unit 60 in a well-balanced manner, the claw member 62 of the separation claw unit 60 is in a single-contact state even when the urging force is weak. There is no contact with the surface. As a result, the separation claw unit 60 having the relatively wide flat-plate-like tip claw portion 62b can be brought into close contact with the peripheral surface of the fixing roller 41 with a weak pressing force.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which the present invention is applied to the fixing device 20 provided in the printer 1 has been described. However, the present invention is not limited to this, and a copying machine other than a printer, a facsimile, a complex machine thereof, or the like. The present invention can also be applied to a fixing device provided in the image forming apparatus.

In the above embodiment, the support member 70 that supports the separation claw unit 60 so as to be swingable is separately provided, and the support member 70 is attached to the housing 30. However, the present invention is not limited thereto. It not, may be configured to support the separation claw unit 60 by the support member which is integrally formed on the housing 30.

  Moreover, in the said embodiment, although the example using the isolation | separation nail | claw unit 60 comprised by the guide member 61, the nail | claw member 62, and a pair of roller member 63 was shown, not only this but the guide member 61 and the roller member 63 are used. You may abbreviate | omit suitably and may use the separation nail | claw unit comprised only with the nail | claw member. In this case, it is preferable that a spring seat having a boss is formed at an appropriate position of the claw member, and the claw member is directly biased by, for example, the compression coil spring 80.

  Moreover, in the said embodiment, while showing the example which forms the fulcrum receiving part 31 in the shape which has a substantially square horizontal cross section and becomes gradually wide toward the opening part from the bottom part, it is not restricted to this, The fulcrum receiving portion 31 may have a regular polygonal horizontal cross section other than a square, and may be formed to gradually widen from the bottom toward the opening, or in a mortar-like or substantially spherical shape. You may form in the hemisphere of an internal diameter slightly larger than the outer diameter of the fulcrum part 62a.

  In the above-described embodiment, the pair of compression coil springs 80 are installed between the spring seat 74 of the support member 70 and the spring seat 64b (65b) of the separation claw unit 60, and the separation claw unit 60 swings. Although an example in which the portion closer to the fixing roller 41 than the fulcrum portion 62a is urged by the pair of compression coil springs 80 is shown, the present invention is not limited thereto, and the separation is performed by, for example, a pair of tension coil springs having one end attached to the housing 30. A configuration may be employed in which the portion closer to the fixing roller 41 than the swinging fulcrum 62a of the claw unit 60 is urged so as to be pulled upward. Further, in the configuration in which the separation claw unit 60 is supported by the support mechanism, a part of the separation claw unit 60 farther from the fixing roller 41 than the swinging fulcrum portion 62a is pushed downward by the pair of compression coil springs. It may be energized.

1 is a cross-sectional front view illustrating an overall configuration of a printer including a fixing device according to an embodiment of the present invention. FIG. 2 is a front view for explaining the configuration of the fixing device according to the embodiment shown in FIG. 1. FIG. 3 is a sectional view of a separation mechanism and a fixing roller of the fixing device shown in FIG. 2. FIG. 3 is a plan view of a separation mechanism of the fixing device shown in FIG. 2. 2A and 2B are plan views of a state in which the separation mechanism is disassembled, in which FIG. 1A shows a part of the housing of the fixing device, FIG. 2B shows a separation claw unit and a compression coil spring, and FIG. 2A and 2B are front views of a state where the separation mechanism is disassembled, in which FIG. 1A shows a part of the housing of the fixing device, FIG. 2B shows a separation claw unit and a compression coil spring, and FIG. 2A and 2B are side views of a state where the separation mechanism is disassembled, in which FIG. 1A shows a part of the housing of the fixing device, FIG. 2B shows a separation claw unit and a compression coil spring, and FIG.

Explanation of symbols

20 fixing device 30 housing 31 fulcrum receiving portion 41 fixing roller 50 separating mechanism (separating means)
60 Separation claw unit (separation claw)
62a Oscillating fulcrum portion 62b Tip claw portion 70 Support member 80 Compression coil spring (coil spring, biasing member)
P paper

Claims (3)

In a fixing device comprising: a fixing roller that fixes a toner image transferred to a sheet to the sheet; and a separating unit that separates the sheet from the fixing roller.
The separating means includes
A separation claw for contacting the peripheral surface of the fixing roller and separating the paper from the fixing roller;
A support member for supporting the separation claw;
An urging member provided on the support member for urging the separation claw toward the peripheral surface of the fixing roller so that the separation claw presses the fixing roller;
A housing for attaching the support member;
Only including,
The separation claw is
A swing fulcrum part that functions as a fulcrum in a swing state;
A front end claw portion provided at a predetermined interval from the swing fulcrum portion and in contact with the peripheral surface of the fixing roller;
The biasing member biases a portion between the swing fulcrum portion and the tip claw portion of the separation claw,
The swinging fulcrum portion of the separation claw contacts the housing by the urging force of the urging member,
The swing fulcrum portion has a substantially spherical shape,
The housing includes a concave fulcrum receiving portion capable of holding the swing fulcrum portion,
The support member supports the separation claw so as to be swingable around a multi-axis direction with the swing fulcrum portion as a fulcrum via the biasing member.
A fixing device. The fixing device according to claim 1 , wherein the fulcrum receiving portion is formed in a concave shape that gradually becomes wider from the bottom toward the opening. It said biasing member is a symmetrical position with respect to the swing fulcrum portion, and, to claim 1 or 2, characterized in that it comprises a pair of coil springs that are arranged along the axial direction of the fixing roller The fixing device described.

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