Image forming device

Abstract

To surely locate and lock a fixing device with respect to an apparatus body, thereby improving the durability of the fixing device.SOLUTION: An image forming apparatus has: a fixing device body; a first fixing member that is disposed on one end of the fixing device body, long in a first direction, and short in a second direction; a second fixing member that is disposed on the other end of the fixing device body, long in a third direction, and short in a fourth direction; an operation unit that rotates the first and second fixing members to place them at a lock position and a release position; and a guide that is formed on a wall body and includes a linear area and a rotation area. The operation unit is rotated to move the first and second fixing members to the rotation area along the linear area, and subsequently the operation unit is rotated to place the first and second fixing members at the lock position, and when the direction of rotation at this time is taken as a fixing direction, the third direction is inclined toward the fixing direction with respect to the first direction. The fixing device is surely located and locked with respect to the apparatus body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Conventionally, image forming devices such as printers, copiers, facsimile machines, and multifunction devices, for example, printers, have an image forming unit in the main body of the printer, i.e., the main body of the device, and in the image forming unit, the surface of a photosensitive drum that has been uniformly charged by a charging roller is exposed by an LED head to form an electrostatic latent image, and the electrostatic latent image is developed by a developing roller to form a toner image, which is then transferred onto paper by a transfer roller and fixed to the paper in a fixing device, thereby forming an image.

[0003] The fixing unit is detachably mounted on the device body so that it can clear any jams that may occur in paper being transported along the paper transport path, and when attached to the device body, it is positioned and locked relative to the device body by a positioning device (see, for example, Patent Document 1).

[0004] FIG. 2 is a perspective view of a conventional fixing unit, FIG. 3 is an exploded perspective view of a conventional positioning device, and FIG. 4 is a view showing the conventional fixing unit in a locked state.

[0005] In the figure, reference numeral 125 denotes a fixing unit, Hz denotes a housing, and 151 denotes a positioning device disposed so as to be swingable relative to the fixing unit 125.

[0006] The housing Hz includes a front panel pf arranged upstream in the paper transport direction, a rear panel pr arranged downstream in the paper transport direction, a top panel pt, a left side panel ps1 arranged on the left side when viewed from the upstream side in the paper transport direction, and a right side panel ps2 arranged on the right side when viewed from the upstream side in the paper transport direction, and a paper entrance Hi is formed in the front panel pf, and a handle 28 is formed on the top panel pt.

[0007] The positioning device 151 also includes a shaft 152 that passes through the housing Hz and extends in the longitudinal direction of the fixing unit 125, a locking member Lr that is attached to the left end of the shaft 152 and positions the fixing unit 125 at the left end relative to the device main body, a locking member Rr that is attached to the right end of the shaft 152 and positions the fixing unit 125 at the right end relative to the device main body, and a lever 154 that is formed integrally with the locking member Lr.

[0008] Groove-shaped guides Gd for guiding the locking members Lr and Rr are formed on the inner wall surfaces of the left side wall facing the left side panel ps1 and the right side wall facing the right side panel ps2 of the printer housing (not shown). An operator grasps the handle 28 and moves the locking members Lr and Rr along the guide Gd to lower the fuser unit 125. When the locking members Lr and Rr reach a rotation range Ar formed at the bottom end of the guide Gd, the operator rotates the lever 154 by a predetermined angle, causing the locking members Lr and Rr to rotate within the rotation range Ar and preventing them from coming off the guide Gd. This positions the fuser unit 125 relative to the main body of the printer.

[0009] In the fixing unit 125, the fixing roller is rotated by a drive system arranged on the right end side, and a drive gear arranged rotatably relative to the device main body is meshed with a transmission gear arranged rotatably relative to the right side panel ps2, and the rotation of the fixing motor is transmitted to the fixing roller via the drive gear and the transmission gear.

[0010] In order to mesh the drive gear with the transmission gear, a stopper 58 is formed adjacent to the rotation area Ar of the guide Gd, and when the lever 154 is rotated by a predetermined angle, the flat surface Sa of the locking member Rr is brought into contact with the stopper 58. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2019-124904 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the conventional fixing unit 125, the positioning device 151 may not be able to reliably lock the fixing unit 125 to the main body of the apparatus.

[0013] That is, if a phase misalignment occurs between the locking members Lr and Rr when the lever 154 is rotated by a predetermined angle to rotate the locking members Lr and Rr in the same direction, the locking member Rr cannot be brought into contact with the stopper 58, and a gap may be formed between the flat surface Sa of the locking member Rr and the stopper 58.

[0014] In this case, the fixing unit 125 cannot be locked to the main body of the apparatus, the drive gear and the transmission gear cannot be properly meshed, and excessive backlash occurs between the drive gear and the transmission gear, resulting in the drive gear and the transmission gear meshing at their tooth tips, shortening the lifespan of the drive gear and the transmission gear and reducing the durability of the fixing unit 125.

[0015] The present invention aims to solve the problems of the conventional fixing unit 125, and to provide an image forming apparatus in which the fixing device can be reliably positioned and locked relative to the apparatus main body, thereby improving the durability of the fixing device. [Means for solving the problem]

[0016] To this end, the image forming apparatus of the present invention comprises a fixing device main body arranged to extend in the longitudinal direction, a first fixing member arranged at one end of the fixing device main body and formed to be long in a first direction perpendicular to the longitudinal direction and short in a second direction perpendicular to the longitudinal direction and the first direction, a second fixing member arranged at the other end of the fixing device main body and formed to be long in a third direction perpendicular to the longitudinal direction and short in a fourth direction perpendicular to the longitudinal direction and the third direction, an operating unit arranged at one end of the fixing device main body to be able to swing freely by a predetermined angle and which rotates the first and second fixing members to place them in a locked position and an unlocked position as it rotates, and a guide formed on a wall of the housing facing the fixing device main body and having a linear area formed extending in the insertion / removal direction of the fixing device relative to the device main body, and a rotation area formed at the end of the linear area on the mounting direction side of the fixing device.

[0017] Then, when the operating unit is rotated to place the first and second fixing members in the release position, and the members are moved along the linear region into the rotation region, the operating unit is rotated in the opposite direction, and the first and second fixing members are placed in the lock position, and the rotation direction of the first and second fixing members is defined as the fixing direction, the third direction is inclined toward the fixing direction with respect to the first direction. [Effects of the Invention]

[0018] According to the present invention, an image forming apparatus includes a fixing device main body arranged to extend in the longitudinal direction, a first fixing member arranged at one end of the fixing device main body and formed to be long in a first direction perpendicular to the longitudinal direction and short in a second direction perpendicular to the longitudinal direction and the first direction, a second fixing member arranged at the other end of the fixing device main body and formed to be long in a third direction perpendicular to the longitudinal direction and short in a fourth direction perpendicular to the longitudinal direction and the third direction, an operating unit arranged to be able to swing freely by a predetermined angle at one end of the fixing device main body and which rotates the first and second fixing members to a locked position and an unlocked position as it rotates, and a guide formed on a wall of the housing facing the fixing device main body and having a linear area formed extending in the insertion / removal direction of the fixing device relative to the device main body, and a rotation area formed at the end of the linear area on the mounting direction side of the fixing device.

[0019] Then, when the operating unit is rotated to place the first and second fixing members in the release position, and the members are moved along the linear region into the rotation region, the operating unit is rotated in the opposite direction, and the first and second fixing members are placed in the lock position, and the rotation direction of the first and second fixing members is defined as the fixing direction, the third direction is inclined toward the fixing direction with respect to the first direction.

[0020] In this case, when the rotation direction of the first and second fixing members when the operating unit is rotated to place the first and second fixing members in the release position and moved along the linear region to the rotation region, and then the operating unit is rotated in the opposite direction to rotate the first and second fixing members to place them in the lock position, the third direction of the second fixing member is inclined toward the fixing direction with respect to the first direction of the first fixing member, so the second fixing member can be sufficiently rotated. Therefore, the fixing device can be reliably positioned and locked relative to the device main body.

[0021] Furthermore, since backlash is appropriately formed in the drive system that transmits the rotation of the fixing drive section to the fixing device, the durability of the fixing device can be improved. [Brief explanation of the drawings]

[0022] [Figure 1] 10 is a view of a D-cut portion formed on a shaft according to an embodiment of the present invention, viewed from the left end side of the fixing unit. FIG. [Figure 2] FIG. 1 is a perspective view of a conventional fixing unit. [Figure 3] FIG. 10 is an exploded perspective view of a conventional positioning device. [Figure 4] FIG. 10 is a diagram illustrating a locked state of a conventional fixing unit. [Figure 5] 1 is a conceptual diagram of a printer according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing a state in which an image forming unit and a fixing unit are removed from an apparatus main body according to the embodiment of the present invention. [Figure 7] FIG. 2 is a perspective view of a fixing unit according to the embodiment of the present invention. [Figure 8] 1 is an exploded perspective view of a positioning device according to an embodiment of the present invention. [Figure 9] 10A and 10B are diagrams illustrating the operation of the locking member on the left end side when positioning the fixing unit according to the embodiment of the present invention. [Figure 10] 10A and 10B are first diagrams illustrating the operation of the locking member on the right end side when positioning the fixing unit according to the embodiment of the present invention. [Figure 11] FIG. 10 is a second diagram illustrating the operation of the locking member on the right end side when positioning the fixing unit according to the embodiment of the present invention. [Figure 12] 10A and 10B are diagrams illustrating a locked state of the locking member on the right end side in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, in which a fixing device as a fixing device and a printer as an image forming apparatus will be described.

[0024] Fig. 5 is a conceptual diagram of a printer according to an embodiment of the present invention, and Fig. 6 is a diagram showing the state in which the image forming units and the fixing unit according to the embodiment of the present invention have been removed from the main body of the printer. In the figures, the positive X-axis direction is the rear direction of the printer 10, the negative X-axis direction is the front direction of the printer 10, the positive Y-axis direction is the left direction of the printer 10, the negative Y-axis direction is the right direction of the printer 10, the positive Z-axis direction is the upward direction of the printer 10, and the negative Z-axis direction is the downward direction of the printer 10.

[0025] In the figure, 10 is a printer, Cs is a housing that is an exterior of the printer 10, and Bd is the main body of the printer 10, that is, the main body of the printer.

[0026] The housing Cs includes a front wall Wf, a back wall Wr, a left wall (not shown) on the left side as viewed from the front wall Wf, a right wall (not shown) on the right side as viewed from the front wall Wf, and a top wall Wt.

[0027] A front cover Cf is arranged from the upper half of the front wall Wf to the front half of the top wall Wt, a top cover Ct is arranged in the rear half of the top wall Wt, and a rear cover Cr is arranged in the upper half of the spine wall Wr, all of which can be opened and closed freely, and a stacker sk is formed in the top cover Ct as a media loading section.

[0028] A paper cassette 11 serving as a medium storage section is disposed at the bottom of the device main body Bd, and paper sheets P serving as a medium are stored in the paper cassette 11. A hopping roller 12 for feeding the paper sheets P to a paper transport path Rt serving as a medium transport path is disposed at the front end of the paper cassette 11, a feed roller 13 is disposed adjacent to the hopping roller 12, and a separation roller 14 is disposed opposite the feed roller 13 and separates the paper sheets P one by one together with the feed roller 13.

[0029] Above the paper cassette 11 in the apparatus main body Bd, an image forming section Q is disposed, which is composed of an image forming unit 16, an LED head (not shown) as an exposure device, and a transfer roller 22 as a transfer member.

[0030] The image forming unit 16 is detachably mounted on the device main body Bd, and the LED head is disposed above the photosensitive drum 21 serving as the image carrier of the image forming unit 16, facing the photosensitive drum 21 and hanging down from the top wall Wt, and the transfer roller 22 is disposed below the photosensitive drum 21, facing the photosensitive drum 21.

[0031] The image forming unit 16 also includes a main body 23 and a toner storage section 24 serving as a developer storage section for storing toner as a developer. A toner storage section Rm serving as a developer storage section is formed below the toner storage section 24 within the main body 23, and the toner supplied from the toner storage section 24 is stored in the toner storage section Rm.

[0032] The main body 23 includes the photosensitive drum 21, a developing roller (not shown) that is rotatably arranged opposite the photosensitive drum 21 and serves as a developer carrier that adheres toner to the photosensitive drum 21 to form a toner image as a developer image, a supply roller (not shown) that supplies toner to the developing roller and serves as a supply member that charges the toner to a predetermined negative polarity potential, and a charging roller (not shown) that is rotatably arranged opposite the photosensitive drum 21 and serves as a charging device that uniformly charges the surface of the photosensitive drum 21.

[0033] The LED head is disposed above the main body 23 facing the photosensitive drum 21, and exposes the photosensitive drum 21, which has been charged by a charging roller, in accordance with image data, to form an electrostatic latent image on the surface of the photosensitive drum 21. The developing roller forms a toner image on the photosensitive drum 21 by adhering toner to the electrostatic latent image.

[0034] The transfer roller 22 is disposed below the main body 23 so as to face the photosensitive drum 21 , and transfers the toner image on the photosensitive drum 21 onto the paper P supplied from the paper cassette 11 .

[0035] Above the paper cassette 11, adjacent to the image forming unit 16, a fixing device 25 as a fixing device is disposed so as to be detachable from the apparatus main body Bd.

[0036] The fixing unit 25 includes a fixing roller R1 as a first fixing member, and a backup roller R2 as a second fixing member that is rotatably disposed in contact with the fixing roller R1, and a heating element (not shown) such as a halogen lamp is disposed within the fixing roller R1. In the fixing unit 25, the toner image transferred onto the paper P is heated by the fixing roller R1 and pressed by the backup roller R2, thereby being fixed onto the paper P.

[0037] In the paper transport path Rt, a pair of transport rollers m1 as a first transport member is arranged at the most upstream side, a pair of transport rollers m2 as a second transport member is arranged downstream of the pair of transport rollers m1, the image forming unit 16 and transfer roller 22 are arranged downstream of the pair of transport rollers m2, the fuser 25 is arranged downstream of the image forming unit 16 and transfer roller 22, a pair of transport rollers m3 as a third transport member is arranged downstream of the fuser 25, and a pair of discharge rollers m4 as a fourth transport member is arranged downstream of the pair of transport rollers m3.

[0038] The paper P in the paper cassette 11 is fed out by a hopping roller 12, separated one sheet at a time by a feed roller 13 and a separation roller 14, fed to a paper transport path Rt, and supplied to the image forming unit Q via a transport roller pair m1 and m2, where a toner image is transferred onto the paper as it is transported between the photosensitive drum 21 and the transfer roller 22 (the nip portion), and the toner image is fixed in a fixing unit 25 to form an image. Subsequently, the paper P on which the image has been formed is transported by the transport roller pair m3, and discharged out of the apparatus main body Bd by the discharge roller pair m4, and stacked on a stacker sk.

[0039] Incidentally, a jam may occur when the paper P is being transported along the paper transport path Rt. In that case, the operator can access the inside of the device main body Bd by opening the front cover Cf, top cover Ct, rear cover Cr, etc., as shown in Figure 6, remove the image forming unit 16, fixing unit 25, etc., take out the paper P, and clear the jam.

[0040] After the jam is cleared, the image forming unit 16, the fixing unit 25, etc. are attached to the device main body Bd. In this embodiment, positioning devices are provided on the image forming unit 16, the fixing unit 25, etc. to ensure that they are attached to the device main body Bd with precision.

[0041] Next, the positioning device disposed in the fixing unit 25 will be described.

[0042] Fig. 7 is a perspective view of a fuser unit according to an embodiment of the present invention, Fig. 8 is an exploded perspective view of a positioning device according to an embodiment of the present invention, Fig. 9 is a diagram illustrating the operation of the locking member on the left side when positioning the fuser unit according to an embodiment of the present invention, Fig. 10 is a first diagram illustrating the operation of the locking member on the right side when positioning the fuser unit according to an embodiment of the present invention, Fig. 11 is a second diagram illustrating the operation of the locking member on the right side when positioning the fuser unit according to an embodiment of the present invention, and Fig. 12 is a diagram illustrating the locked state of the locking member on the right side according to an embodiment of the present invention. Note that in Fig. 9, the positive X-axis direction is the rearward direction in printer 10, the negative X-axis direction is the forward direction in printer 10, the positive Y-axis direction is the leftward direction in printer 10, the negative Y-axis direction is the rightward direction in printer 10, the positive Z-axis direction is the upward direction in printer 10, and the negative Z-axis direction is the downward direction in printer 10. Also, in Figure 7, the positive direction of the Xa axis is the rear direction of the fixing device 25, the negative direction of the Xa axis is the front direction of the fixing device 25, the positive direction of the Ya axis is the left direction of the fixing device 25, the negative direction of the Ya axis is the right direction of the fixing device 25, the positive direction of the Za axis is the upward direction of the fixing device 25, and the negative direction of the Za axis is the downward direction of the fixing device 25.

[0043] In the figure, 25 is a fixing unit, Hz is a housing as a fixing unit main body arranged extending in the longitudinal direction of the fixing unit 25, and 51 is a positioning device arranged so as to be swingable relative to the fixing unit 25.

[0044] The housing Hz comprises a front panel pf arranged upstream in the transport direction of the paper P (Figure 5), a rear panel pr arranged downstream in the transport direction of the paper P, a top panel pt, a left side panel ps1 arranged on the left side when viewed from the upstream side in the transport direction of the paper P, and a right side panel ps2 arranged on the right side when viewed from the upstream side in the transport direction of the paper P, and a paper entrance Hi is formed in the front panel pf as a media entrance that takes in the paper P discharged from between the image forming unit 16 and the transfer roller 22 into the housing Hz, and a handle 28 is formed to protrude from the top panel pt.

[0045] The positioning device 51 also includes a shaft 52 that passes through the housing Hz and extends in the Ya axis direction (longitudinal direction) of the fixing unit 25, a left-end locking member Lr that is attached to the left end of the shaft 52 and serves as a first fixing member for positioning the housing Hz with respect to the device main body Bd at one end side and as a first positioning member, a right-end locking member Rr that is attached to the right end of the shaft 52 and serves as a second fixing member for positioning the housing Hz with respect to the device main body Bd at the other end side and as a second positioning member, and a lever 54 that is integral with the locking member Lr and is formed extending radially outward from the locking member Lr as an operating part.

[0046] A D-cut portion 57L is formed at the left end of shaft 52, a D-shaped hole 59L is formed on the surface of locking member Lr facing shaft 52, a D-cut portion 57R is formed at the right end of shaft 52, and a D-shaped hole 59R is formed on the surface of locking member Rr facing shaft 52. By fitting D-cut portions 57L and 57R into holes 59L and 59R, respectively, shaft 52 and locking members Lr and Rr are connected, and when lever 54 is rotated a predetermined angle, locking members Lr and Rr are linked and rotated in the same direction and phase by the same angle. D-cut surfaces SL and SR are formed on D-cut portions 57L and 57R to transmit rotation from locking member Lr to locking member Rr.

[0047] The locking members Lr and Rr are formed into an "I" shape by cutting two points in the circumferential direction of a cylindrical member having a predetermined thickness, and each has parallel rectangular flat surfaces Sa and an arcuate surface Sb extending between the flat surfaces Sa.

[0048] When the fixing unit 25 is viewed from the left side, the lever 54 is arranged so as to be able to swing freely by a predetermined angle in the direction of arrow A, which is the counterclockwise direction, and in the direction of arrow B, which is the clockwise direction, relative to the rear panel pr, and as the lever 54 rotates, it rotates the locking members Lr and Rr to place them in a locked position and an unlocked position, which will be described later.

[0049] To this end, a stepped stopper 62 is formed on the left side panel ps1 and the right side panel ps2 as a first restricting member and retaining portion that restricts the rotation of the lever 54 in the direction of arrow A and holds the lever 54, and a protrusion 63 is formed as a second restricting member that restricts the rotation of the lever 54 in the direction of arrow B, and the lever 54 is rotated by an operating angle set between the stopper 62 and the protrusion 63.

[0050] Furthermore, a flexible protrusion 64 is formed between the stopper 62 and the protrusion 63 so as to give the operator a clicking sensation when the lever 54 is rotated in the directions of arrows A and B.

[0051] A groove-like guide LGd is formed on the inner wall surface of the left side wall, which serves as a first wall opposite the left side panel ps1 of the housing Cs of the printer 10, to guide the locking member Lr when inserting or removing the fixing unit 25 into or from the device main body Bd, and a groove-like guide RGd is formed on the inner wall surface of the right side wall, which serves as a second wall opposite the right side panel ps2, to guide the locking member Rr.

[0052] Each guide LGd, RGd has an open upper end and consists of a linear area Ar1 extending in the insertion / removal direction of the fixing unit 25 relative to the device main body Bd (Za axis direction of the fixing unit 25), and a rotation area Ar2 formed at the end of the linear area Ar1 on the mounting direction side of the fixing unit 25, i.e., at the lower end.

[0053] The groove width of the linear region Ar1 is set slightly larger than the distance between the flat surfaces Sa of the locking members Lr and Rr, i.e., the width of the locking members Lr and Rr, and smaller than the distance between the arcuate surfaces Sb, i.e., the length of the locking members Lr and Rr.

[0054] That is, the locking member Lr is formed to be long in a first direction perpendicular to the longitudinal direction of the housing Hz and short in a second direction perpendicular to the longitudinal direction and the first direction, and the locking member Rr is formed to be long in a third direction perpendicular to the longitudinal direction of the housing Hz and short in a fourth direction perpendicular to the longitudinal direction and the third direction.

[0055] When the lever 54 is rotated to contact the protrusion 63, the locking members Lr and Rr are rotated in accordance with the rotation of the lever 54 and are placed in the vertical position as the release position, as shown in Fig. 10. As a result, the locking members Lr and Rr can be moved along the linear area Ar1, and the fixing unit 25 is released from the device main body Bd, allowing it to be inserted into or removed from the device main body Bd.

[0056] In contrast, when the locking members Lr, Rr are located in the rotation range Ar2, if the lever 54 is rotated a predetermined angle and abuts against the stopper 62, the locking members Lr, Rr are rotated in accordance with the rotation of the lever 54 and are placed in an inclined position serving as the locked position, as shown in Figures 9, 11, and 12. As a result, the locking members Lr, Rr are fixed in the rotation range Ar2, the fixing unit 25 is locked to the device main body Bd, and insertion and removal into and from the device main body Bd is prevented.

[0057] Therefore, by rotating the lever 54 in the direction of arrow B, placing the locking members Lr and Rr in the release position, and moving them along the linear area Ar1 to the rotational area Ar2, the lever 54 is then rotated in the direction of arrow A, placing the locking members Lr and Rr in the lock position, whereby the fixing unit 25 can be positioned and locked relative to the device main body Bd.

[0058] In this embodiment, one of the guides LGd, RGd has a stopper 68 formed as an abutment surface at the end of the guide RGd on the linear region Ar1 side (the front panel pf side of the fixation unit 25) in the rotation region Ar2, and the flat surface Sa of the locking member Rr placed in the inclined position abuts against the stopper 68 in the fourth direction of the locking member Rr. The angle formed by the stopper 68 and the linear region Ar1 is set larger than the operating angle of the lever 54 when the lever 54 is rotated and the locking members Lr, Rr are placed in the locked position.

[0059] Incidentally, a drive system for transmitting rotation of a fixing motor (not shown) serving as a fixing drive unit to the fixing roller R1 is disposed on the right end side of the housing Hz in the fixing unit 25. When the fixing unit 25 is attached to the apparatus main body Bd and positioned and locked relative to the apparatus main body Bd by the positioning device 51, a drive gear gr1 rotatably supported within the apparatus main body Bd and a transmission gear gr2 rotatably supported relative to the housing Hz are brought into mesh with each other in the drive system, as shown in FIGS.

[0060] However, even if the lever 54 is brought into contact with the stopper 62, if a phase misalignment occurs between the locking members Lr and Rr, the flat surface Sa of the locking member Rr cannot be brought into contact with the stopper 68, forming a gap between the flat surface Sa and the stopper 68, and the fixing unit 25 cannot be reliably locked to the apparatus main body Bd. As a result, the drive gear gr1 and the transmission gear gr2 cannot be properly engaged with each other.

[0061] Therefore, in this embodiment, the D-cut portions 57L and 57R are formed on the shaft 52 so that there is no phase misalignment between the locking members Lr and Rr.

[0062] FIG. 1 is a view of a D-cut portion formed on a shaft according to an embodiment of the present invention, as viewed from the left end side of a fixing unit.

[0063] In the figure, 52 is a shaft, 57L and 57R are D-cut portions, and SL and SR are D-cut surfaces.

[0064] In this embodiment, when the D-cut surface SL is placed horizontally, the D-cut surface SR is formed so as to be inclined by 3° in the direction of arrow A in Fig. 7. In other words, when the rotation direction of the locking member Rr when the lever 54 is rotated in the direction of arrow A is defined as the fixing direction, the third direction of the locking member Rr is inclined by 3° toward the fixing direction with respect to the first direction of the locking member Lr.

[0065] As described above, in this embodiment, when the lever 54 is rotated in the direction of arrow B to place the locking members Lr and Rr in the vertical position and moved along the linear region Ar1 to the rotation region Ar2, and then the lever 54 is rotated in the direction of arrow A to place the locking members Lr and Rr in the tilted position, and the direction of arrow A, which is the rotation direction of the locking members Lr and Rr, is defined as the fixed direction, the third direction of the locking member Rr is tilted toward the fixed direction with respect to the first direction of the locking member Lr, so that the locking member Rr can be sufficiently rotated toward the locked position. As a result, the fixing unit 25 can be reliably positioned and locked relative to the apparatus main body Bd.

[0066] Furthermore, when the lever 54 is rotated in the direction of arrow A, the flat surface Sa of the locking member Rr comes into contact with the stopper 68 before the lever 54 comes into contact with the stopper 62, so that the fixing unit 25 can be reliably locked to the device main body Bd and the drive gear gr1 and the transmission gear gr2 can be properly engaged with each other.

[0067] Therefore, backlash is properly formed between the drive gear gr1 and the transmission gear gr2, and the drive gear gr1 and the transmission gear gr2 do not mesh with each other at their cutting edges, which results in a longer life for the drive gear gr1 and the transmission gear gr2, and an improved durability of the fixing unit 25.

[0068] Furthermore, as shown in Figure 10, when the direction of the reaction force FG that the transmission gear gr2 receives when rotation is transmitted from the drive gear gr1 is defined as a reaction force rotation direction K1 centered on the locking member Rr, the direction in which the fixing unit 25 is inserted into or removed from the apparatus main body Bd is defined as an insertion / removal direction K2, and the direction in which the stopper 68 extends is defined as a stopper extension direction K3, the reaction force rotation direction K1, the insertion / removal direction K2, and the stopper extension direction K3 are inclined relative to one another.

[0069] This makes it possible to prevent the lock member Rr from being rotated in the rotation range Ar2 or moved in the insertion / removal direction of the fixing unit 25 as the transmission gear gr2 receives the reaction force FG.

[0070] In addition, to prevent the fixing unit 25 from rotating around the locking members Lr and Rr within the device main body Bd when it receives the reaction force FG, a post pst is formed as a rotation preventing member that protrudes downward from the bottom of the fixing unit 25 on the downstream side in the reaction force rotation direction K1, and is engaged with a hole formed in a frame or the like (not shown) of the device main body Bd.

[0071] Furthermore, if the operator intentionally presses the lever 54 hard against the stopper 62 when the flat surface Sa of the locking member Rr is brought into contact with the stopper 68 before the lever 54 contacts the stopper 62, the shaft 52 will twist, preventing the locking member Rr from being pressed with too much force against the stopper 68. Therefore, the locking member Rr, the stopper 68, etc. will not be damaged, and the fixing unit 25 can be reliably locked to the apparatus main body Bd.

[0072] Although the present embodiment has been described with reference to a monochrome printer 10, the present invention can also be applied to a color printer equipped with multiple image forming units. Also, the present embodiment has been described with reference to a direct transfer printer 10 in which the toner image on the photosensitive drum 21 is directly transferred to the paper P, but the present invention can also be applied to a secondary transfer printer in which the toner image on the photosensitive drum 21 is transferred to a transfer belt, and the toner image on the transfer belt is transferred to the paper P.

[0073] Although the present embodiment has been described with reference to the printer 10, the present invention can also be applied to image forming devices such as copying machines, facsimile machines, and multifunction machines.

[0074] The present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention. [Explanation of symbols]

[0075] 10 Printers 25 Fixing unit 54 Lever Ar1 linear range Ar2 rotation range Bd device body Cs case Hz Housing LGd, RGd Guide Lr, Rr locking members

Claims

1. (a) a fixing device main body extending in a longitudinal direction; (b) a first fixing member disposed at one end of the fixing device body, the first fixing member being long in a first direction perpendicular to the longitudinal direction and short in a second direction perpendicular to the longitudinal direction and the first direction; (c) a second fixing member disposed on the other end side of the fixing device main body, the second fixing member being long in a third direction perpendicular to the longitudinal direction and short in a fourth direction perpendicular to the longitudinal direction and the third direction; (d) an operating unit that is disposed at one end of the fixing device body so as to be swingable by a predetermined angle, and that rotates the first and second fixing members to a lock position and an unlock position as the operating unit rotates; (e) a guide formed on a wall of the housing facing the fixing device main body, the guide having a linear area formed extending in the insertion / removal direction of the fixing device relative to the device main body, and a rotation area formed at an end of the linear area on the side of the installation direction of the fixing device; (f) An image forming apparatus characterized in that when the operation unit is rotated, the first and second fixing members are placed in the release position, and the first and second fixing members are moved along the linear region into the rotation region, and then the operation unit is rotated in the opposite direction to place the first and second fixing members in the lock position, the rotation direction of the first and second fixing members is defined as the fixing direction, and the third direction is inclined toward the fixing direction with respect to the first direction.

2. 2. The image forming apparatus according to claim 1, wherein when the second fixed member is in the locked position, a surface formed on the second fixed member and a contact surface formed in the rotation area are brought into contact with each other in the fourth direction.

3. 3. The image forming apparatus according to claim 1, wherein the operation unit is disposed on a side of the fixing device main body where the first fixed member is disposed.

4. 4. The image forming apparatus according to claim 1, wherein a drive system for transmitting rotation of a drive unit for fixing to the fixing device is disposed on the side of the fixing device main body where the second fixed member is disposed.

5. (a) a holding portion for holding an operation unit is disposed in the fixing device main body; (b) When the operating unit is rotated, the surface formed on the second fixed member and the contact surface formed in the rotation area are brought into contact with each other before the operating unit contacts the holding unit.

6. 6. The image forming apparatus according to claim 1, wherein the first and second fixed members are disposed on both ends of a shaft that penetrates the fixing device main body.

7. (a) the drive system includes a drive gear and a transmission gear that is meshed with the drive gear; (b) When the direction of the reaction force received by the transmission gear is the reaction force rotation direction centered on the second fixed member, the direction in which the abutment surface extends is inclined with respect to the reaction force rotation direction and the insertion / removal direction of the fixing device.

8. An image forming apparatus according to any one of claims 1 to 7, wherein the width of the linear region of the guide is smaller than the lengths of the first and second fixed members in the first and third directions, and larger than the lengths of the first and second fixed members in the second and fourth directions.

9. 8. The image forming apparatus according to claim 2, wherein the angle formed by the contact surface and the linear region is larger than the operating angle of the operating unit when the operating unit is rotated and the first and second fixing members are placed in the lock position.

Images