KR101366568B1 - Fusing device and image forming apparatus having the same - Google Patents

Abstract

Disclosure of Invention An object of the present invention is to disclose an improved fixing apparatus and an image forming apparatus having the same, which can be miniaturized while improving the fixing performance. The fixing apparatus of the present invention includes a case having a frame, a heating roller disposed inside the case, a first pressure roller contacting the heating roller to form a first fixing nip, and a first pressure roller in a conveying direction of the print medium. A second pressurizing roller installed on the downstream side of the roller and contacting the heating roller to form a second fixing nip; and a first elastic member for pulling the frame to press the first pressing roller and the second pressing roller toward the heating roller. It is composed. The fixing device is designed to ensure the stability of the behavior of the printing medium so that no jams or images are damaged while the printing medium passes through the fixing device.

Description

FIELD OF THE INVENTION The present invention relates to a fixing device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a fixing apparatus for improving performance and miniaturization and an image forming apparatus having the same.

      An image forming apparatus is an apparatus for forming an image on a print medium according to an input image signal. Examples of the image forming apparatus include a printer, a copier, a fax machine, and a multifunction printer incorporating these functions.

      An image forming apparatus adopting an electrophotographic method scans light on a photosensitive member charged to a predetermined potential to form an electrostatic latent image on the surface of the photosensitive member, and then develops a visible toner image by introducing toner into the latent image. The toner image developed on the photosensitive member is transferred to the print medium, and the toner image transferred to the print medium is fixed to the print medium while passing through the fixing device.

      A general fixing device includes one heating roller having a heat source therein and one pressing roller which contacts the heating roller to form a fixing nip. When the print medium to which the toner image is transferred enters between the rotating roller and the pressure roller, the toner image is fixed to the print medium by the heat transmitted from the inside of the heating roller and the pressure applied between the heating roller and the pressure roller.

In recent years, since the image forming apparatus is increasing in speed and size, it is necessary to improve the performance of the fixing apparatus and to make the fixing apparatus smaller.

Since the performance of the fixing apparatus is proportional to the width of the fixing nip, the diameter of the pressing roller should be increased to improve the performance of the fixing apparatus having one pressing roller. However, in order to increase the diameter of the pressure roller, the diameter of the heating roller must also be correspondingly large, so that the fixing apparatus is large in size, so that the image forming apparatus cannot be miniaturized.

In view of this point, in recent years, a method of using two relatively small pressure rollers has been proposed, an example of which is illustrated in FIG. 1. The fixing apparatus shown in FIG. 1 includes a heating roller 1 having a heat source 1a therein, and a first pressing roller 2 arranged along the conveying direction of the printing medium M to be in close contact with the heating roller 1. And a second press roller 3. The first pressing roller 2 is elastically pressurized toward the heating roller 1 by the first compression spring 4 installed on the opposite side of the heating roller 1, and the second pressing roller 3 has a second compression spring ( It is elastically pressurized toward the heating roller 1 by 5). As such, when the two pressure rollers are used, the width of the fixing nip is increased as a whole, thereby improving the fixing performance and miniaturizing the fixing apparatus to some extent.

However, in the fixing apparatus as shown in FIG. 1, the first compression spring 4 is installed on the opposite side of the heating roller 1 to press the first pressure roller 2 toward the heating roller 1, but in such a structure, the first compression spring 4 is pressed. In order to secure the installation space 6 of the spring 4, the height of the fixing apparatus must be increased, and thus, there is a certain limit in miniaturizing the image forming apparatus.

On the other hand, when designing a fixing apparatus, the consideration with the improvement of the fixing performance and the miniaturization of the fixing apparatus is to allow the print media to pass through the fixing apparatus through an optimized path possible.

When the print media passes through the fixing device, curling occurs in the printing medium. If the curling media is not properly guided, jams may occur inside the fixing device, or the printing medium may rub against components installed around the printing medium. The images formed on the wall may be damaged.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an improved fixing apparatus and an image forming apparatus having the same, which can be miniaturized while improving the fixing performance.

Another object of the present invention is to provide an improved fixing apparatus and an image forming apparatus having the same so that a print medium can stably pass through the fixing apparatus without causing an image defect.

A fixing apparatus according to the present invention for achieving this object is provided with a case comprising a frame and a cover; and a heating roller provided on the cover side; A first pressing roller to be formed; and a second pressing roller which is provided on the frame side and installed downstream of the first pressing roller in a conveying direction of a print medium, and which contacts the heating roller to form a second fixing nip. And a first elastic member for pulling the frame to press the first pressing roller and the second pressing roller toward the heating roller.

One side of the frame may be hinged to the cover.

The first elastic member may be composed of a tension spring having one end coupled to the frame and the other end coupled to the cover.

In addition, the fixing apparatus of the present invention may further include a second elastic member for pressing the second pressure roller toward the heating roller.

The second elastic member may have a compression spring having one end supported by the frame and the other end supporting the second pressure roller.

In addition, the fixing apparatus of the present invention is further provided with a support member elastically supported by one side is coupled to the second pressure roller and the second elastic member, and a pressure release lever rotatably coupled to the support member, When the pressure release lever rotates, the frame rotates in the direction of pulling the first elastic member, and the support member may move in a direction away from the heating roller.

The angle θ1 of the straight line X1 connecting the center of the heating roller and the center of the first pressure roller to the straight line X2 connecting the center of the heating roller and the center of the second pressing roller is 45 °. It is preferable that it is -55 degrees.

In addition, the fixing apparatus of the present invention may include a guide claw which prevents the printing medium passing through the second fixing nip from being wound on the heating roller, including a contact portion in contact with the heating roller.

The distance a from the straight line X2 connecting the center of the heating roller to the center of the second pressure roller to the contact portion is 0.6 ≦ a / r ≦ 0.96 in relation to the radius r of the heating roller. It is preferable.

The distance b from the straight line X3 connecting the uppermost point and the lowest point of the second fixing nip to the contact portion is 0.16 ≦ b / r ≦ 0.4 in relation to the radius r of the heating roller. desirable.

The guide claw further includes an extension surface which extends from the contact portion and faces a path through which the print medium passed through the second fixing nip passes, and the extension direction of the extension surface and the most upstream point of the second fixing nip are the lowest. It is preferable that the angle (theta) 2 which the straight line X3 which connects a point makes is 0 degrees-8 degrees.

In addition, the fixing apparatus of the present invention may include a print medium guide extending on a path through which the print medium passed through the second fixing nip passes.

The angle θ3 of the straight line X3 connecting the uppermost point and the lowest point of the second fixing nip with the print medium guide is preferably 140 ° to 160 °.

In addition, the fixing apparatus of the present invention includes a first media guide roller disposed downstream of the print media guide in a transport direction of the print media, and the transport direction of the print media in the second fixing nip is the first media guide. It is preferable that the angle (theta) 4 which forms with the conveyance direction of the printing medium in a roller is 120 degrees-140 degrees.

In addition, the fixing apparatus of the present invention further comprises a guide roller installed on the print medium guide, and a distance from the straight line X2 connecting the center of the heating roller and the center of the second press roller to the center of the guide roller. (c) is preferably 1.2 ≦ c / r ≦ 2.4 in relation to the radius r of the heating roller.

In addition, the fixing apparatus of the present invention further comprises a first media guide roller installed in the print media guide on the downstream side of the guide roller, the straight line connecting the center of the heating roller and the center of the second pressure roller (X2) The distance d from the center to the center of the first medium guide roller is preferably 2 ≦ d / r ≦ 3.2 in relation to the radius r of the heating roller.

In addition, the fixing apparatus according to the present invention includes a cover in which a heating roller is disposed; and a frame having one side hinged to the cover; and at least two pressure rollers installed on the frame; and the pressure rollers are in close contact with the heating roller. And a tension spring that elastically supports the frame so as to be provided.

In addition, the image forming apparatus according to the present invention is an image forming apparatus having a fixing apparatus, the fixing apparatus is a cover in which a heating roller is disposed therein; and one side of the frame rotatably coupled to the cover; and the frame And at least two pressing rollers installed therebetween and a first elastic member installed between the cover and the frame to press the other side of the frame toward the cover.

The present invention adopts a plurality of pressure rollers to improve the fixing performance.

In addition, the present invention can be miniaturized by improving the installation structure of the elastic member for pressing the pressure roller toward the heating roller so that the height of the fixing device is not increased due to the installation space of the elastic member.

In addition, the present invention can prevent damage or jams of the image by properly disposing the components so that the print medium can be stably behave in the fixing apparatus.

In addition, according to the present invention, it is possible to easily release the fixing pressure acting between the pressure rollers and the heating roller by using one pressure release lever, so that the paper jammed in the fixing apparatus can be easily removed when a jam occurs.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 2, the image forming apparatus 10 according to the present invention includes a main body 10a, a print medium supply apparatus 20, a developing apparatus 30, a fixing apparatus 100, a discharge apparatus 40 and A duplex printing apparatus 50 is provided.

The print medium supply device 20 supplies the print medium M to the developing device 30. The print medium supply device 20 includes a tray 21 on which the print medium M is loaded, a pickup roller 22 for picking up the print media loaded on the tray 21 one by one, and a pick-up print medium. It comprises a feed roller 23 for feeding toward the (30).

The developing device 30 develops an image on a print medium conveyed from the print medium supply device 20. The developing apparatus 30 includes a photosensitive member 31 on which a latent electrostatic image is formed on the surface by the optical scanning device 60, a charging roller 32 for charging the photosensitive member 31, and an electrostatic latent image formed on the photosensitive member 31. And a developing roller 33 for pressing the print medium toward the photosensitive member 31 so that the toner image of the photosensitive member 31 and the developing roller 33 to be developed are transferred to the printing medium.

The fixing device 100 applies heat and pressure to the print medium to fix the toner image to the print medium. An input guide 70 for guiding a print medium entering the fixing device 100 is installed at the inlet of the fixing device 100. Detailed description of the structure of the fixing device 100 will be described later.

The discharge device 40 includes a first medium roller 41 and a second medium roller 42 which are sequentially installed to discharge the print medium passing through the fixing device 100 to the outside of the main body 10a.

The duplex printing apparatus 50 transfers the print media on which one side is printed back upstream of the developing apparatus 30 so as to print both sides of the print media. The duplex printing apparatus 50 includes a duplex printing guide 52 forming a duplex printing path 51 and a series of duplex printing rollers 53 installed on the duplex printing path 51 to convey a print medium. It is configured by. When printing on both sides, the printing medium having one side printed is discharged by the second medium roller 42, inverted at a specific time point, and transferred to the double-sided printing path 51, and again by the double-sided printing rollers 53. 30, the remaining one side is printed while passing through the developing apparatus 30 and the fixing apparatus 100 in sequence.

3 is a view showing the configuration of a fixing device according to an embodiment of the present invention, Figures 4 and 5 are perspective views showing a partial configuration of the fixing device according to an embodiment of the present invention.

As shown in FIG. 3, the fixing apparatus 100 includes a case 100a including a frame 110 and a cover 120. The heating roller 130 and a plurality of pressure rollers 140 and 150 are installed in the case 100a to face the heating roller 130. The pressure rollers 140 and 150 are in close contact with the heating roller 130 so that a constant fixing pressure is maintained between the pressing rollers 140 and 150. In this embodiment, but the example is provided with two pressure rollers, the number of the pressure rollers can be appropriately changed as needed. Hereinafter, the pressure roller positioned upstream with respect to the conveying direction of the print medium will be referred to as the first pressure roller 140, and the pressure roller positioned downstream will be referred to as the second pressure roller 150.

The heating roller 130 has a heat source 131 for applying heat to the print medium to which the toner is transferred. The heat source 131 may be configured as a halogen lamp, a hot wire or an induction heater.

The first press roller 140 and the second press roller 150 are shafts 141 and 151 formed of a metal material such as aluminum or steel, and an elastic layer 142 surrounding the shafts 141 and 151 ( 152, respectively. As the first pressing roller 140 is compressed to the heating roller 130, the elastic layer 142 elastically deforms to form the first fixing nip N1. As the second pressing roller 150 is pressed onto the heating roller 130, the elastic layer 152 forms the second fixing nip N2. The elastic layers 142 and 152 are typically formed of silicone rubber, and a release layer (not shown) is provided on the surfaces of the elastic layers 142 and 152 to prevent the print medium from sticking to the pressure rollers.

As shown in FIGS. 3 and 4, the frame 110 has a base panel 110a and sidewalls 110b extending upward from both ends of the base panel 110a. A hinge groove 111 is formed at one side of the side wall 110b, and the hinge groove 111 is coupled to the hinge shaft 121 provided at the cover 120. Accordingly, the frame 110 may rotate around the hinge shaft 121 of the cover 120.

The first pressing roller 140 and the second pressing roller 150 are installed in the frame 110. The side wall 110b of the frame 110 is formed with a first coupling groove 112 to which an end of the first pressing roller 140 is coupled. As the coupling boss 141a is fixed to the first coupling groove 112 in a state in which the coupling boss 141a is coupled to the shaft 141 of the first pressing roller 140, the first pressing roller 140 is frame 110. ) Is rotatably installed.

In addition, the frame 110 has a second coupling groove 113 to which the end of the second pressing roller 150 is coupled. A support member 170 is coupled to an end of the shaft 151 of the second pressing roller 150, and the support member 170 is coupled to the second coupling groove 113 of the frame 110. The support member 170 has a shaft coupling hole 171 into which the shaft 151 of the second pressing roller 150 is inserted. In addition, the guide groove in which a portion of the frame 110 is inserted into the side of the support member 170 so that the support member 170 can linearly move in the second coupling groove 113 in a state in which the support member 170 is coupled to the frame 110. 172 is formed.

The first elastic member 160 (see FIG. 3) is installed between the frame 110 and the cover 120. The first elastic member 160 pulls the frame 110 toward the cover 120 such that the first pressing roller 140 and the second pressing roller 150 installed on the frame 110 are pressed against the heating roller 130. do.

The first elastic member 160 may be composed of a tension spring 161 having one end coupled to the frame 110 and the other end coupled to the cover 120. On the other side of the frame side wall 110b, a locking protrusion 114 is formed on the other end of the tension spring 161, and a locking ring 114 is provided at the other end of the tension spring 161. A spring coupling hole 122 is engaged with the 161b.

When the first elastic member 160 is installed in the above structure, the height of the fixing apparatus 100 does not increase to secure the installation space of the first elastic member 160. Therefore, the image forming apparatus may be miniaturized as much as possible. Can be.

As the first elastic member 160 installed between the frame 110 and the cover 120 pulls the frame 110, the second pressing roller 150 installed on the frame 110 comes into close contact with the heating roller 130. However, there may be a limit in compressing the second pressing roller 150 to the heating roller 130 using only the first elastic member 160. The second elastic member 180 for elastically pressing the second pressure roller 150 toward the heating roller 130 is installed between the support member 170 and the frame 110.

The second elastic member 180 may be composed of a compression spring 181. One end of the compression spring 181 is supported by the frame 110 and the other end elastically supports the support member 170 coupled to the second pressure roller 150. The frame 110 has a first support protrusion 115 into which one side of the compression spring 181 is inserted, and the support member 170 has a second support protrusion 173 into which the other side of the compression spring 181 is inserted. .

As can be seen in Figure 4, the inner and outer sides of the support member 170 is different in shape. 4, the inner side surface 170a of the support member 170 is opened at the portion where the compression spring 181 is inserted, which is inserted into the second support protrusion 173. The compressed spring 181 is to prevent the interference with the inner surface (170a) of the support member 170. On the other hand, when looking at the support member 170 on the right in Figure 4, the outer surface 170b of the support member 170 is not open at the portion where the compression spring 181 is inserted. A lever coupling protrusion 174 is formed on the outer surface 170b of the support member 170, and the lever coupling protrusion 174 is coupled to the pressure release lever 190 to be described later.

As shown in Figure 3 and 5, the heating roller 130 is installed inside the cover 120. The cover 120 is provided with a guide claw 123 to prevent the print medium passing through the second fixing nip N2 from being attached to the heating roller 130 and being wound.

The guide claw 123 has a body 123a having a contact portion 123b in contact with the surface of the heating roller 130, and the body 123a is elastically biased toward the heating roller 130 so that the contact portion 123b is predetermined. It is provided with a torsion spring (not shown) to be in contact with the surface of the heating roller 130 by the pressure.

The body 123a of the guide claw 123 has an outer side surface 123c and an inner side surface 123d which meet each other at the contact portion 123b. The outer surface 123c of the body 123a faces the path 101 through which the print medium passed through the second fixing nip N2 passes, and the inner surface 123d of the body 123a is formed of the heating roller 130. Adjacent to the surface.

The cover 120 further includes a print medium guide 124 for guiding the print medium passing through the second fixing nip N2, and a discharge medium extending from the print medium guide 124 toward the discharge device 40 (see FIG. 2). A guide 125 is provided.

The print media guide 124 includes a plurality of guide ribs 124a. Guide rollers 126 are disposed in the width direction of the print medium guide 124. The guide roller 126 prevents the image formed on the print medium from being damaged by the guide ribs 124a when the print medium is guided by the guide ribs 124a.

The discharge guide 125 is bent from the print medium guide 124 and extended upward. First badge guide rollers 127 are installed at one end of the discharge guide 125, and second badge guide rollers 128 are installed at the other end of the discharge guide 125.

The first media guide roller 127 and the second media guide roller 128 rotate in engagement with the driving rollers 11 and 12 (see FIG. 2) installed in the main body 10a of the image forming apparatus. The print medium passing through N2 is transferred to the discharge device 40.

In addition, the fixing device 100 of the present invention is designed to ensure miniaturization and to ensure the stability of the behavior of the print media to prevent jams or damage to the image during the passage of the print media through the fixing device 100. do.

6 is a view showing the positional relationship between the components in the fixing device according to an embodiment of the present invention.

As shown in FIG. 6, the straight line X1 connecting the center O of the heating roller 130 and the center O ′ of the first pressure roller 140 is the center O of the heating roller 130. And an angle θ1 formed with a straight line X2 connecting the center O ″ of the second pressing roller 150 is 45 ° to 55 °.

When the angle θ1 is greater than 55 °, it is disadvantageous to miniaturize the fixing device 100 as the distance between the first pressure roller 140 and the second pressure roller 150 increases, and the first fixing nip N1. The density of the image may be blurred as the heating roller 130 slips on the image of the printing medium M while the printing medium M having passed through) enters the second fixing nip N2. In addition, a jam may occur when the front end of the printing medium does not smoothly enter the second fixing nip N2 and hits the second pressing roller 150.

On the other hand, when the angle θ1 is smaller than 45 °, there is a problem that the first pressing roller 140 and the second pressing roller 150 interfere with each other as the distance between the two pressing rollers 140 and 150 decreases. Design difficulties arise in that strict standard tolerances must be applied to avoid this. In addition, when the angle θ1 is too narrow, the size of the press rollers 140 and 150 is inevitably reduced, and thus, a fixing nip of sufficient size cannot be secured, thereby deteriorating the fixing performance.

The distance a from the straight line X2 connecting the center O of the heating roller 130 and the center O ″ of the second pressure roller 150 to the contact portion 123b of the guide claw 123 is heated. It is preferable to design so that the following relational expression (Equation 1) may be satisfied with respect to the radius r of the roller 130. FIG.

0.6≤a / r≤0.96 (Equation 1)

Further, the distance b between the straight line X3 connecting the most upstream point P and the most downstream point Q of the second fixing nip N2 to the contact portion 123b of the guide claw 123 is the heating roller 130. It is preferable to design such that the following relational expression (Equation 2) is satisfied with respect to the radius r of.

0.16≤b / r≤0.4 (Equation 2)

For example, when the radius r of the heating roller 130 is about 12.5 mm, a is preferably 7.5 mm or more and 12 mm or less, and b is preferably 2 mm or more and 5 mm or less.

The guide claw 123 serves to separate the print medium from the heat roller 130 in an abnormal situation in which the print medium is attached to the heating roller 130. When the printing process is normally performed, the guide claw 123 does not come into contact with the print medium. Not good.

However, if the distance a from the straight line X2 to the contact portion 123b or the distance b from the straight line X3 to the contact portion 123b is too small, the print medium may be removed from the guide claw 123 even in the normal printing process. The image may be damaged by contacting the outer surface 123c.

On the other hand, if the distance (a) (b) is too large, the guide claw 123 heats the print medium because the print medium reaches the guide claw 123 while the print medium is already wound around the heating roller 130. Even if separated from the roller 130, the occurrence of jams in the interior of the fixing device 100 can not be avoided.

Therefore, the guide claw 123 is preferable in terms of being designed to satisfy the above expressions (1) and (2) in order to prevent the occurrence of image defects and jams.

Moreover, it is preferable that the angle (theta) 2 which the direction which the outer side surface 123c of the guide claw 123 extends, and the straight line X3 make is 0 degrees-8 degrees. This prevents the outer surface 123c of the guide claw 123 from protruding too much toward the path 101 through which the print medium M passes so that the image may not be damaged due to friction between the print medium and the guide claw 123. Considered.

After the print medium passes through the first fixing nip N1 and the second fixing nip N2, curling occurs in the printing medium (a phenomenon in which the printing medium curls toward the heating roller 130). At this time, if the print medium is bent in a direction opposite to the direction in which the curl is generated before the print medium is completely cooled, the curl may be alleviated to some extent.

The print medium guide 124 provided downstream of the second fixing nip N2 is designed to smoothly guide the print medium passing through the second fixing nip N2 and to mitigate curls generated in the printing medium.

The angle θ3 of the print medium guide 124 and the straight line X3 connecting the most upstream point P and the most downstream point Q of the second fixing nip N2 is preferably 140 ° to 160 °. .

When the angle θ3 is greater than 160 °, the curl of the print medium may not be effectively reduced because the print medium guide 124 is substantially parallel to the advancing direction of the print medium passing through the second fixing nip N2.

The smaller the angle θ3 is, the more effective it is in terms of removing the curl of the print medium. However, if the angle θ3 is too small, as the advancing direction of the print medium changes rapidly after passing through the second fixing nip N2, the possibility of the print medium being damaged or jam is increased. Therefore, the minimum value of the angle θ3 should be about 140 degrees.

In addition, it is preferable that the conveyance direction of the print medium in the second fixing nip N2 is formed between the conveyance direction of the print medium in the first medium guide roller 127 and the angle θ4 is 120 ° to 140 °. This is considered so that the print medium guided by the print medium guide 124 can smoothly enter between the first medium guide roller 127 and the driving roller 11.

In addition, from the straight line X2 connecting the center O of the heating roller 130 and the center O ″ of the second pressing roller 150 to the center of the guide roller 126 installed on the print medium guide 124. The distance c is preferably 1.2 ≦ c / r ≦ 2.4 with respect to the radius r of the heating roller 130. For example, when the radius r of the heating roller 130 is approximately 12.5 mm, the distance c is preferably 15 mm to 30 mm.

If the distance (c) is too large, it is impossible to effectively prevent an image from being damaged because the print medium reaches the guide roller 126 only after the print medium guide 124 substantially rubs against the print medium guide 124. On the other hand, if the distance (c) is too small, the print medium passing through the second fixing nip N2 just passes the guide roller 126 and is then moved by the print medium guide 124 downstream of the guide roller 126. As it begins to be guided, the guide roller 126 may become obsolete.

In addition, the first medium guide roller 127 installed on the print medium guide 124 from a straight line X2 connecting the center O of the heating roller 130 and the center O ″ of the second pressure roller 150. The distance d to the center is preferably 2 ≦ d / r ≦ 3.2 with respect to the radius r of the heating roller 130. For example, when the radius r of the heating roller 130 is approximately 12.5 mm, the distance d is preferably 25 mm to 40 mm.

If the distance d is too large, the period in which the print medium reaches the first medium guide roller 127 and the friction with the print medium guide 124 becomes long, so that the image is more likely to be damaged, and the distance d Is too small, the component placement becomes difficult in relation to the guide roller 126.

Meanwhile, as shown in FIGS. 3 and 4, the fixing device 100 includes a pressure release lever 190 for releasing pressure acting between the pressure rollers 140 and 150 and the heating roller 130. . When the printing medium is caught between the pressure rollers 140 and 150 and the heating roller 130 during the printing operation, the user uses the pressure release lever 190 to press between the pressure rollers 140 and 150 and the heating roller 130. After removing the pressure acting in the jam can be easily removed.

7 and 8 are views for explaining the operation of the pressure release lever in the fixing device according to an embodiment of the present invention. FIG. 7 illustrates a normal state, that is, a state in which the pressure acting between the pressure rollers 140 and 150 and the heating roller 130 is not released. FIG. 8 shows the pressure through the pressure release lever 190. The unlocked state is shown.

As shown in FIGS. 4, 7 and 8, the lever guide protrusion 116 is formed on the side wall 110b of the frame 110, and the pressure release lever 190 is coupled to the lever guide protrusion 116. A guide long hole 191 is provided.

In the normal state as shown in FIG. 7, the lever guide protrusion 116 inserted into the guide long hole 191 is located below the guide long hole 191. Meanwhile, the washer 116a is coupled to the lever guide protrusion 116 while the pressure release lever 190 is coupled to the lever guide protrusion 116, thereby preventing the pressure release lever 190 from being separated.

In addition, the pressure release lever 190 has a support member coupling hole 192 coupled to the lever coupling protrusion 174 formed on the support member 170. When the user lowers or raises the handle 193 of the pressure release lever 190, the pressure release lever 190 rotates about the lever coupling protrusion 174 in the vertical direction.

When the user lowers the handle 193 in the state as shown in FIG. 7, the guide long hole 191 of the pressure release lever 190 rotates about the lever coupling protrusion 174 downward, and thus, the guide long hole normally. The lever guide protrusion 116 located below the 191 is positioned above the guide hole 191 as shown in FIG. 8.

However, when the lever guide protrusion 116 is located above the guide hole 191 (see the lever guide protrusion indicated by the imaginary line in FIG. 7), the distance between the lever engaging protrusion 174 and the lever guide protrusion 116 ( e1) is shorter than the distance e2 when the lever guide protrusion 116 is located below the guide hole 191, so as to rotate the pressure release lever 190 as shown in Figure 8 to the pressure release lever 190 As a result, the supporting member 170 moves in the A direction. Then, the pressure acting between the second pressing roller 150 and the heating roller 130 is released.

In addition, the pressure release lever 190 has an interference portion 194 that interferes with the cover 120 at the time of rotation. The interference part 194 protrudes toward the cover 120 from one end of the pressure release lever 190 to rotate about the lever coupling protrusion 174 when the user lowers the handle part 193. Interfere with the bottom.

The operation when the interference part 194 of the pressure release lever 190 interferes with the cover 120 will be described in more detail as follows. When the user starts to lower the handle 193 in the state as shown in FIG. 7, the first surface 194a of the interference unit 194 contacts the cover 120. As described above, when the user lowers the handle 193 further while the first surface 194a of the interference unit 194 interferes with the cover 120, the interference unit 194 pushes the cover 120. However, since the cover 120 is fixed inside the main body 10a of the image forming apparatus, the frame 110 rotates in the B direction by the force of the pressure release lever 190 pushing the cover 120. As such, when the frame 110 moves, the first pressing roller 140 also moves together with the frame 110 to release the pressure acting between the first pressing roller 140 and the heating roller 130.

8 illustrates a state in which the pressure release lever 190 is rotated to the end, in which the second surface 194b of the interference unit 194 contacts the edge portion 120a of the cover 120. A vertex 194c exists between the first surface 194a and the second surface 194b of the interference portion 194, and the second surface 194b of the interference portion 194 is an edge portion of the cover 120. Since the edge portion 120a of the cover 120 is supported by the apex 194c in the state of contact with the 120a, the state as shown in FIG. 8 is maintained unless an external force is applied to the pressure release lever 190.

As described above, the user uses the pressure release lever 190 between the first pressing roller 140 and the heating roller 130 and the fixing pressure between the second pressing roller 150 and the heating roller 130. The fixing pressure acting at can be released, and jam can be easily removed while the pressure is released.

Meanwhile, after finishing the jam removing operation, the user may lift the handle 193 of the pressure release lever 190 to return to a state as shown in FIG. 7.

1 is a view showing the configuration of a conventional fixing device.

2 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

3 is a view showing a configuration of a fixing device according to an embodiment of the present invention.

4 and 5 are a perspective view showing an extract of some components in the fixing device according to an embodiment of the present invention.

6 is a view showing the positional relationship between the components in the fixing device according to an embodiment of the present invention.

7 and 8 are views for explaining the operation of the pressure release lever in the fixing device according to an embodiment of the present invention.

Description of the Related Art [0002]

100: fixing device 110: frame

120: cover 130: heating roller

140: first pressing roller 150: second pressing roller

160: first elastic member 161: tension spring

170: support member 180: second elastic member

181: compression spring 190: pressure release lever

Claims (23)

A case including a frame and a cover; and A heating roller provided on the cover side; and A first pressing roller provided on the frame side and contacting the heating roller to form a first fixing nip; A second pressing roller provided on the frame side and installed downstream of the first pressing roller in a conveying direction of a print medium, the second pressing roller contacting the heating roller to form a second fixing nip; A first elastic member which pulls the frame to press the first pressing roller and the second pressing roller toward the heating roller; A second elastic member pressurizing the second pressing roller toward the heating roller; Fixing apparatus comprising a. The method of claim 1, One side of the frame is a fixing device characterized in that the hinge is coupled to the cover. The method of claim 1, The first elastic member is a fixing device characterized in that it comprises a tension spring one end is coupled to the frame and the other end is coupled to the cover. delete The method of claim 1, The second elastic member is a fixing device characterized in that it comprises a compression spring, one end is supported on the frame and the other end supports the second pressure roller. The method of claim 1, One side is further coupled to the second pressure roller and the other side is further provided with a support member elastically supported by the second elastic member, and a pressure release lever rotatably coupled to the support member, The frame is rotated in the direction of pulling the first elastic member when the pressure release lever rotates, the fixing member characterized in that the support member moves in a direction away from the heating roller. The method of claim 1, An angle θ 1 of the straight line X1 connecting the center of the heating roller and the center of the first pressure roller to the straight line X2 connecting the center of the heating roller and the center of the second pressure roller is 45. Fixing device, characterized in that ° ~ 55 °. The method of claim 1, And a guide claw which prevents the print medium passing through the second fixing nip from being wound on the heating roller, including a contact portion in contact with the heating roller. 9. The method of claim 8, The distance (a) from the straight line (X2) connecting the center of the heating roller and the center of the second pressure roller to the contact portion satisfies the following relation in relation to the radius (r) of the heating roller. Fixing device. 0.6≤a / r≤0.96 9. The method of claim 8, The distance (b) from the straight line (X3) connecting the uppermost point and the lowest point of the second fixing nip to the contact portion satisfies the following relation in relation to the radius (r) of the heating roller. Fixing device. 0.16≤b / r≤0.4 9. The method of claim 8, The guide claw further includes an extension surface facing the path through which the print medium extends from the contact portion and passes through the second fixing nip. Fixing apparatus characterized in that the angle (θ2) formed by a straight line (X3) connecting the extension direction of the extension surface and the most upstream point and the lowest point of the second fixing nip is 0 ° ~ 8 °. The method of claim 1, And a print media guide extending on a path through which the print media passed through the second fixing nip passes. The method of claim 12, A fixing device characterized in that the angle (θ3) of the straight line (X3) connecting the uppermost point and the lowest point of the second fixing nip with the print medium guide is 140 ° ~ 160 °. 14. The method of claim 13, Further comprising a first medium guide roller disposed on the downstream side of the print medium guide in the conveying direction of the print medium, A fixing device characterized in that the conveyance direction of the printing medium in the second fixing nip and the conveying direction of the printing medium in the first media guide roller are θ4 between 120 ° and 140 °. The method of claim 12, Further provided with a guide roller installed on the print medium guide, The distance c between the straight line X2 connecting the center of the heating roller and the center of the second press roller to the center of the guide roller satisfies the following relation in relation to the radius r of the heating roller. Fixing apparatus characterized in that. 1.2≤c / r≤2.4 16. The method of claim 15, Further provided with a first medium guide roller installed in the print medium guide on the downstream side of the guide roller, The distance d between the straight line X2 connecting the center of the heating roller and the center of the second pressing roller to the center of the first medium guide roller is the following in relation to the radius r of the heating roller. A fixing device characterized by satisfying the relational expression. 2≤d / r≤3.2 A cover having a heating roller disposed therein; and A frame hinged to one side of the cover; And At least two pressure rollers installed on the frame; and A tension spring elastically supporting the frame such that the pressure rollers are in close contact with the heating rollers; A second elastic member for pressing one of the pressure rollers toward the heating roller; Fixing apparatus comprising a. An image forming apparatus comprising a fixing apparatus, wherein the fixing apparatus A cover having a heating roller disposed therein; and A frame rotatably coupled to one side of the cover; and At least two pressure rollers installed on the frame; and A first elastic member installed between the cover and the frame to press the other side of the frame toward the cover; A second elastic member for pressing one of the pressure rollers toward the heating roller; The image forming apparatus comprising: 19. The method of claim 18, And the first elastic member includes a tension spring having one end coupled to the frame and the other end coupled to the cover. 19. The method of claim 18, The at least two pressure rollers include a first pressure roller forming a first fixing nip with the heating roller, and a second pressure roller forming a second fixing nip with the heating roller, The angle θ1 of the straight line X1 connecting the center of the heating roller and the center of the first pressure roller to the straight line X2 connecting the center of the heating roller and the center of the second pressing roller is 45 °. An image forming apparatus, characterized in that ~ 55 °. 21. The method of claim 20, A guide claw which prevents the printing medium from being wound on the heating roller, including a contact portion contacting the heating roller and an extension surface facing the path through which the printing medium passes through the second fixing nip and passes through the second fixing nip. Equipped, From a straight line (X2) connecting the center of the heating roller and the center of the second pressure roller from the distance (a) to the contact portion and a straight line (X3) connecting the most upstream point and the lowest point of the second fixing nip And the distance (b) to the contact portion satisfies the following relational expression in relation to the radius (r) of the heating roller. 0.6≤a / r≤0.96, 0.16≤b / r≤0.4 22. The method of claim 21, And an angle θ2 formed between the extension direction of the extension surface and the straight line X3 is 0 ° to 8 °. 21. The method of claim 20, And a print medium guide extending on a path through which the print medium passed through the second fixing nip passes. And an angle (θ3) formed by a straight line (X3) connecting the uppermost point and the lowest point of the second fixing nip with the print medium guide is 140 ° to 160 °.

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