JP2004061781A - Opening / closing mechanism of fuser - Google Patents

Abstract

An opening / closing mechanism of a fixing device of a printer that performs printing on continuous paper by an electrophotographic method, wherein the continuous paper printer does not need to have means for avoiding interference with various parts around the opening / closing mechanism. It is to provide an opening and closing mechanism.
A first frame rotatably supports one roller, a second frame fixed to a frame of a printer and rotatably supporting another roller, and a second frame rotatably supporting the other roller. A drive member for driving the first frame, and a compression coil spring for urging the first frame so that one roller is separated from the other when the drive member is not driving the first frame. By doing so, the above problem was solved.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an opening and closing mechanism of a fixing device of a printer that performs printing on continuous paper by electrophotography.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a printer that forms an image in units of pages using electrophotography by using continuous paper as recording paper. Some of such printers include a mechanism for pulling back the unprinted portion of the continuous paper to the transfer position after printing to prevent waste paper from being generated. Further, the fixing device for fixing the toner to the recording paper includes an opening / closing mechanism for allowing the heat roller pair to be able to be separated from and connected to each other. When the continuous paper is pulled back, the opening / closing mechanism separates the heat roller pair to reduce the frictional resistance applied to the continuous paper. Further, the heat roller pair is configured to be separated in order to prevent the continuous paper from closely contacting the high-temperature heat roller when printing is not performed, thereby preventing the occurrence of burns and burns.
[0003]
The conventional opening / closing mechanism has a torsion spring for urging one roller of the heat roller pair to separate one roller from the other, and a driving unit capable of urging one roller toward the other. That is, when one of the rollers is urged toward the other by the driving means, the rollers of the heat roller pair are brought into close contact with each other, so that the toner can be fixed on the recording paper. On the other hand, when the urging by the driving means is stopped, one roller of the heat roller pair is separated from the other by the repulsive force of the torsion spring.
[0004]
However, in the case of a large continuous paper printer, one of the heat roller pairs biased by the torsion spring reaches several kg, so the coil diameter of the torsion spring is set large enough to support one of the heat roller pairs. There is a need. In addition, since the torsion spring is mounted so that the coil portion of the torsion spring protrudes largely outside the heat roller pair, it is necessary to secure a space for installing the torsion spring around the heat roller pair. For this reason, the continuous paper printer having the conventional opening / closing mechanism needs to provide a means for avoiding interference between the coil of the torsion spring and various parts around the opening / closing mechanism, which has led to an increase in the number of parts of the continuous paper printer. .
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and provides a fixing device opening / closing mechanism that does not require a means for avoiding interference with various components around the opening / closing mechanism in a continuous paper printer.
[0006]
[Means for Solving the Problems]
To achieve the above object, an opening and closing mechanism for a fixing device according to the present invention includes a first frame rotatably supporting one roller and a second frame fixed to a frame of a printer and rotatably supporting the other roller. A driving member for driving the first frame in a direction in which one roller is in close contact with the other; a compression coil spring for urging the first frame in a direction in which one roller is separated from the other; A first connecting pin that connects the second frame and the second frame in a hinge shape, a support shaft rotatably attached to the second frame via a third connecting pin, and the support shaft are inserted through the first connecting pin. A movable bearing member having a first through hole and a second through hole drilled perpendicular to the first through hole, the movable bearing member being movable in the axial direction of the support shaft, and the support shaft being fixed to the first frame and being inserted therethrough. The first And a support pin rotatably supported in the second through-hole within a range where the third through-hole does not interfere with the support shaft. The movable bearing member is in contact with an end of the support shaft and is inserted through the support shaft.
[0007]
The compression coil spring can apply a repulsion force equivalent to that of the torsion spring to one roller in a much smaller installation space than the torsion spring. Therefore, according to the present invention, the space for installing the elastic member is much smaller than when the torsion spring is used as the elastic member. As a result, it is not necessary to provide a means for avoiding interference of various parts around the opening / closing mechanism on the printer side, and it is possible to prevent an increase in the number of parts of the continuous paper printer. Further, the second frame is movable by being guided by the support shaft between a position where one roller is in contact with the other roller and a position where one roller is separated from the other roller.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The printer according to the present embodiment is a laser beam printer that performs printing using a so-called electrophotographic method.
[0009]
FIG. 1 is a perspective view of a laser beam printer 10 according to an embodiment of the present invention. In FIG. 1, a printer 10 includes a scanning optical device 14 for irradiating a laser beam, a photosensitive drum 16 on which a latent image is formed by the laser beam from the scanning optical device 14, and a toner image formed by attaching toner to the latent image. , A transfer unit 44 for transferring the toner image to the continuous paper, a fixing device 22 for fixing the toner image to the continuous paper, and the like are housed in the housing 12. The continuous paper is transported through the transfer unit 44 and the fixing device 22 by a transport mechanism provided in the housing 12.
[0010]
The scanning optical device 14 deflects and scans a light beam emitted from a laser diode and modulated according to image information by a polygon mirror 14a. The scanning light deflected and scanned by the polygon mirror 14a is reflected by the mirror 14b and is applied to a predetermined position (irradiation position) on the surface of the photosensitive drum 16 located below the scanning optical device 14.
[0011]
The photosensitive drum 16 is configured to be rotationally driven at a constant speed clockwise in FIG. The surface of the photosensitive drum 16 faces the scanning optical device 14, the developing unit 42, and the transfer unit 44.
[0012]
The transfer unit 44 is provided with a transfer charger 46 for transferring the toner image onto the continuous paper. The transfer charger 46 is configured to perform a transfer operation (transfer position) on the photosensitive drum 16 by a retraction mechanism (not shown). It is possible to move between a transfer position and a position retracted (a retract position).
[0013]
The fixing device 22 is provided with a heat roller 128 having a built-in heat source and a press roller 130 for bringing the continuous paper into close contact with the heat roller 128 so as to be positioned above and below the continuous paper. The press roller 130 can be moved by the opening / closing mechanism 200 between a position where the press roller 130 is pressed against the heat roller 128 (operation position) and a position where the press roller 130 is separated (retreat position). The detailed configuration of the opening / closing mechanism 200 will be described later.
[0014]
The continuous paper is inserted from an insertion opening 26 formed on the right side of the housing 12 in the drawing, passes through the above-described transfer unit 44 and the fixing device 22, and is discharged from a discharge opening 28 provided on the left side of the housing 12 in the drawing. You. The continuous paper is transported by the tractor unit 20 provided between the transfer unit 44 and the fixing device 22. The tractor unit 20 includes a pair of tractor belts 62 provided with projections at regular intervals so as to be engaged with feed holes provided at both ends in the width direction of the continuous paper, and a pulley 61 for driving the belts. The pulley 61 is driven by a tractor motor 84 which is a step motor. In the following description, in the continuous paper transport path, the insertion port 26 side is referred to as upstream in the transport direction, and the discharge port 28 side is referred to as downstream in the transport direction.
[0015]
The main motor 82, the tractor motor 84, and the fuser motor 86 are controlled by the control unit 24.
[0016]
The scanning optical device 14 forms a latent image on the surface of the photosensitive drum 16 by irradiating the photosensitive drum 16 with laser light based on image information. Then, the latent image formed on the photosensitive drum 16 becomes a toner image with toner attached (that is, developed) in the developing unit 42. The toner image on the photosensitive drum 16 is transferred by the transfer charger 46 of the transfer unit 44 onto a continuous sheet conveyed between the photosensitive drum 16 and the transfer charger 46. Then, the continuous paper on which the toner image has been transferred in the transfer unit 44 is conveyed to the fixing device 22 and is heated and pressed to fix the toner image. The continuous paper on which the toner image has been fixed is discharged from the discharge port 28 to the outside of the printer 10.
[0017]
As described above, the printer 10 of the present embodiment uses continuous paper. When a series of printing processes is completed, the printer 10 ejects the trailing end of the continuous paper to the outside of the printer so that the user can confirm the printing result or separate the printed page. It is configured as follows. At this time, a page on which printing has not been performed is located in the printer (downstream from the transfer unit). However, when the next printing process is performed, the continuous paper is pulled back and printing is performed. It is configured to be used effectively.
[0018]
When the continuous paper is pulled back, the heat roller 128 is separated from the press roller 130 by the opening / closing mechanism 200 to reduce the frictional resistance applied to the continuous paper. Further, when the printing is completed and the trailing end of the printing end page of the continuous paper is discharged out of the printer, the continuous paper is kept in close contact with the high-temperature heat roller 128 to prevent the occurrence of burns and burns. To prevent this, the heat roller 128 is separated from the press roller 130 by the opening / closing mechanism 200.
[0019]
The opening / closing mechanism 200 will be described below with reference to the drawings. As shown in FIG. 1, the upper surface and side surfaces of the heat roller 128 are covered by a first frame 220, and the lower surface and side surfaces of the press roller 130 are covered by a second frame 230. The first frame 220 rotatably supports the heat roller 128, and the second frame 230 rotatably supports the press roller 130.
[0020]
The second frame 230 is fixed to the case frame of the housing 12. The first frame 220 is hingedly connected to the second frame 230 via connection pins 240. From the close contact state between the heat roller 128 and the press roller 130 shown in FIG. 1, the first frame 220 can rotate clockwise in FIG. 1 around the connecting pin 240 as a fulcrum to separate the heat roller 128 from the press roller 130. .
[0021]
One end 213a of a cam-shaped follower 213 is in contact with the upper surface of the first frame 220. The cam follower 213 is rotatably supported by the case frame of the housing 12 via the connecting pin 214 at the bent portion. On the other hand, the other end 213b of the cam follower 213 is in contact with the cam 212. Here, by rotating the cam 212 clockwise in FIG. 1 from the close contact state between the heat roller 128 and the press roller 130 shown in FIG. 1, the contact position between the cam 212 and the other end 213b of the cam follower 213 is lowered. As a result, one end 213a of the cam follower 213 rises. The cam 212 is driven to rotate by a cam drive motor 211 controlled by the control unit 24.
[0022]
The first frame 220 is urged upward (in the direction of rotating the first frame 220 clockwise in FIG. 1) by an urging member 250 using a compression coil spring. Therefore, when the cam 212 is rotated clockwise in FIG. 1 to raise one end 213a of the cam follower 213 from the close contact state between the heat roller 128 and the press roller 130 shown in FIG. 1, the repulsive force of the compression coil spring of the biasing member 250 is increased. As a result, the heat roller 128 is separated from the press roller 130. On the other hand, from this state, by rotating the cam 212 counterclockwise in FIG. 1 and lowering the one end 213a of the cam follower 213, the first frame 220 rotates counterclockwise in FIG. The heat roller 128 comes into close contact with the press roller 130.
[0023]
FIG. 2 is a perspective view of the fixing device 22 and the opening / closing mechanism 200 partially cut away. FIG. 2 shows the fixing device 22 and the opening / closing mechanism 200 in a state where the heat roller 128 is in close contact with the press row 130. The urging member 250 includes a support shaft 251, a connection pin 252, a movable bearing member 253, a support pin 254, and a compression coil spring 255.
[0024]
A through-hole 251a is drilled at the lower end of the support shaft 251. A connecting pin 252 is fitted into the through-hole 251a and a through-hole (not shown) drilled on the front side of the second frame 230 in FIG. . The support shaft 251 can swing about the connection pin 252 along the side face on the near side in FIG. 2 of the second frame 230.
[0025]
The movable bearing member 253 includes a shaft through hole 253a into which the support shaft 251 is inserted, and a support pin through hole into which a support pin 254 pierced in a direction perpendicular to the front side surface of the first frame 220 in FIG. It has a hole 253b.
[0026]
The support pin 254 has a through hole into which the support shaft 251 is inserted (described later). One end of the support pin 254 is fixed to the first frame 220. The support pin 254 is movable along the support shaft 251 together with the movable bearing member 253. The support pin 254 can swing while sliding with the support pin through hole 253b of the movable bearing member 253.
[0027]
A compression coil spring 255 is mounted between the lower end of the support shaft 251 and the movable bearing member 253. The position of the lower end of the support shaft 251 is held by the second frame 230 by a connecting pin 252, and the compression coil spring 255 urges the movable bearing member 253 toward the upper end of the support shaft 251.
[0028]
FIG. 3 is an exploded view of the biasing member 250. The support shaft 251 includes a pedestal portion 251b having a through hole 251a, a lower shaft portion 251c integrally formed with the pedestal portion 251b, an upper shaft portion 251d, and a stopper 251e formed at an upper end of the upper shaft portion 251d. And.
[0029]
The diameter of the stopper 251e is larger than the inner diameter of the shaft through-hole 253a of the movable bearing member 253, and prevents the movable bearing member 253 from being detached from the support shaft 251 due to the repulsive force of the compression coil spring 255.
[0030]
A female screw 251g is formed at the upper end of the lower shaft portion 251c, and a male screw 251f is formed at the lower end of the upper shaft portion 251d in the axial direction of the support shaft. The screw 251f is screwed into the female screw 251g for fastening. By doing so, the upper shaft portion 251d and the lower shaft portion 251c are integrated. As described above, since the diameter of the stopper 251e is configured to be larger than the inner diameter of the shaft through hole 253a of the movable bearing member 253, the movable bearing member 253, the support pin 254, and the compression coil spring 255 are respectively attached to the support shaft 251. When mounting, the upper shaft portion 251d and the lower shaft portion 251c are separated, and the upper end of the lower shaft portion 251c is inserted into the movable bearing member 253, the support pin 254, and the compression coil spring 255.
[0031]
The pedestal portion 251b has a larger diameter than the lower shaft portion 251c, and the lower end of the compression coil spring 255 is supported by a step formed between the pedestal portion 251b and the lower shaft portion 251c. The movable bearing member 253 can be urged upward.
[0032]
Further, as shown in FIG. 3, the size of the through hole 254a of the support pin 254 is configured to be larger than the diameter of the upper shaft portion 251d and the lower shaft portion 251c. Therefore, even if the support shaft is inserted into the through hole 254 a of the support pin 254, the support pin 254 can rotate to some extent in the support pin through hole 253 b of the movable bearing member 253.
[0033]
As described above, in the biasing member 250 according to the present embodiment, the angle formed between the line connecting the connecting pin 240 and the support pin 254 and the support shaft 251, and the line connecting the connection pin 240 and the connection pin 252 and the support shaft 251. 251 can be changed. Therefore, according to the present embodiment, the movable bearing member 253 can freely move up and down along the support shaft 251.
[0034]
Therefore, by rotating the cam 212 from the close contact state between the heat roller 128 and the press roller 130 shown in FIG. 2, the first frame 220 moves smoothly upward in FIG. As a result, as shown in FIG. 4, the heat roller 128 is separated from the press roller 130.
[0035]
As described above, according to this embodiment, the force for separating the heat roller 128 from the press roller 130 is applied by the compression coil spring 255 provided between the first frame 220 and the second frame 230. The size of the opening and closing mechanism can be suppressed to the minimum necessary.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a laser beam printer according to an embodiment of the present invention.
FIG. 2 is a partially cutaway perspective view of a fixing device and an opening / closing mechanism according to the embodiment of the present invention.
FIG. 3 is an exploded view of a biasing member according to the embodiment of the present invention.
FIG. 4 is a partially cutaway perspective view of a fixing device and an opening / closing mechanism according to the embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 10 laser beam printer 22 fixing unit 24 control unit 128 heat roller 130 press roller 200 opening / closing mechanism 211 cam drive motor 212 cam 213 cam follower 220 first frame 230 second frame 240 connection pin 250 biasing member 251 support shaft 252 connection pin 253 Movable bearing member 254 Support pin 255 Compression coil spring

Claims (3)

An opening and closing mechanism for a fixing device of a printer that performs printing on continuous paper by electrophotography, wherein the opening and closing mechanism includes:
A first frame rotatably supporting one of the heat roller pairs of the fixing device;
A second frame fixed to the frame of the printer and rotatably supporting the other roller of the heat roller pair of the fixing device;
A driving member that drives the first frame in a direction in which one roller of the heat roller pair is in close contact with the other,
A compression coil spring for urging the first frame in a direction in which the one roller is separated from the other, and for separating the one roller from the other when the driving member is not driving the first frame; ,
A first connecting pin for connecting the first frame and the second frame in a hinge shape;
A support shaft rotatably mounted to the second frame via a third connecting pin;
A first through-hole through which the support shaft is inserted, and a second through-hole drilled perpendicular to the first through-hole, and a movable bearing member movable in the axial direction of the support shaft;
A third through-hole fixed to the first frame, through which the support shaft is inserted, and rotatable within the second through-hole as long as the third through-hole does not interfere with the support shaft; A support pin supported by the
Has,
An opening / closing mechanism for a fixing device, wherein both ends of the compression coil spring abut against the movable bearing member and the end of the support shaft, and are inserted through the support shaft. A cam follower rotatable with respect to a printer frame via a second connecting pin, one end of which presses and biases the first frame toward the second frame;
A cam which abuts on the cam follower, rotates the cam follower around the second connecting pin, and can hold one end of the cam follower at either the first position or the second position;
Has,
When one end of the cam follower is at the first position, the cam follower regulates the position of the first frame so that the one roller is in close contact with the other,
When one end of the cam follower is at the second position, the cam follower regulates the position of the first frame so that the one roller can be separated from the other by the repulsive force of the compression coil spring. The fixing device opening / closing mechanism according to claim 1. 3. The opening / closing mechanism for a fixing device according to claim 1, wherein at least a part of the support shaft is housed inside the first frame and / or the second frame. 4. .

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