JP7841364B2 - Image forming apparatus - Google Patents

Description

This invention relates to an image forming apparatus.

Conventionally, in image forming devices such as printers, copiers, facsimile machines, and multifunction devices, for example, in electrophotographic printers, the printer body, i.e., the device body, houses an image forming unit, a transfer unit, and a fuser as a fixing device. In the image forming unit, the surface of a photoreceptor drum, uniformly charged by a charging roller, is exposed to light to form an electrostatic latent image. This electrostatic latent image is developed by a developing roller to form a toner image. This toner image is transferred to the paper by the transfer unit and fixed in the fuser, thereby forming an image on the paper and performing printing.

Incidentally, there are printers that allow the fuser to be detached from the main unit of the device in order to remove paper jams caused by paper on which an image has been formed, or to perform maintenance on the fuser (see, for example, Patent Document 1).

Japanese Patent Publication No. 2020-38342

However, in the conventional printers described above, the space created when the fuser is removed from the main unit cannot be effectively utilized, making it impossible to reliably and easily remove, for example, jammed paper.

The present invention aims to solve the problems of conventional printers by providing an image forming apparatus that can reliably and easily remove jammed media by effectively utilizing the space created when the fuser unit is removed from the main body of the apparatus.

Therefore, the image forming apparatus of the present invention includes a fixing device detachably mounted to the main body of the apparatus, and a guide unit disposed downstream of the fixing device in the media transport direction, which guides the media.

The guide unit comprises a first media guide and a second media guide that is movably disposed relative to the first media guide.

Furthermore, when the fixing device is removed from the main body of the device, a space is formed within the main body of the device.

The second media guide, positioned opposite the first media guide, forms a first media transport path between them, and, while positioned within the space, opens the first media transport path.

According to the present invention, the image forming apparatus includes a fixing device detachably mounted to the apparatus body, and a guide unit disposed downstream of the fixing device in the media transport direction, which guides the media.

The guide unit comprises a first media guide and a second media guide that is movably disposed relative to the first media guide.

Furthermore, when the fixing device is removed from the main body of the device, a space is formed within the main body of the device.

The second media guide, positioned opposite the first media guide, forms a first media transport path between them, and, while positioned within the space, opens the first media transport path.

In this case, since the first media transport path is opened with the second media guide placed in the space, even if a media jam occurs in the first media transport path due to a media on which an image has been formed, the media can be reliably and easily removed.

Therefore, the space created within the device body when the fixing device is removed from the main body can be effectively utilized.

This is a cross-sectional view of the main part of a printer according to an embodiment of the present invention. This is a schematic diagram of a printer according to an embodiment of the present invention. This is a conceptual diagram of an image forming unit in an embodiment of the present invention. This diagram illustrates the relationship between the fuser, the main paper transport path, and the first and second branch transport paths in an embodiment of the present invention. This is a perspective view of a guide unit in an embodiment of the present invention. This is a perspective view of the discharge guide and intermediate guide in an embodiment of the present invention, viewed from the front left. This is a perspective view of the discharge guide and intermediate guide in an embodiment of the present invention, viewed from the front right. This is a perspective view of the intermediate guide in an embodiment of the present invention, viewed from the left front. This is a perspective view of the intermediate guide in an embodiment of the present invention, viewed from the front right. This is a perspective view of the main part of the intermediate guide in an embodiment of the present invention, viewed from the front left. This is a perspective view of the reversal guide in an embodiment of the present invention, viewed from the front left. This is a perspective view showing the support structure for the discharge roller pair and the reversing roller pair in an embodiment of the present invention. This is the first figure showing the rotational transmission system when the opening/closing frame in an embodiment of the present invention is placed in an upright position. This is a second figure showing the rotational transmission system when the opening/closing frame in an embodiment of the present invention is placed in an upright position. This figure shows the state of the guide unit when the opening/closing frame in an embodiment of the present invention is placed in an inclined position. This figure shows the rotational transmission system when the opening/closing frame in an embodiment of the present invention is placed in an inclined position. This is a perspective view of the main part of a printer for illustrating the first procedure for removing paper from the first branch transport path in an embodiment of the present invention. This is a cross-sectional view of a key part of a printer illustrating the first procedure for removing paper from the first branch transport path in an embodiment of the present invention. This is a perspective view of the main part of a printer for illustrating a second procedure for removing paper from a first branch transport path in an embodiment of the present invention. This is a cross-sectional view of a key part of a printer illustrating a second procedure for removing paper from a first branch transport path in an embodiment of the present invention. This is a perspective view of the main part of a printer for illustrating a third step in removing paper from the first branch transport path in an embodiment of the present invention. This is a cross-sectional view of a key part of a printer illustrating a third step in removing paper from a first branch transport path in an embodiment of the present invention. This is a perspective view of the main part of a printer for illustrating the fourth step in removing paper from the main paper transport path in an embodiment of the present invention. This is a cross-sectional view of a key part of a printer illustrating a fourth step in removing paper from the main paper transport path in an embodiment of the present invention.

The embodiments of the present invention will be described in detail below with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

Figure 2 is a schematic diagram of a printer according to an embodiment of the present invention. In the figure, 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.

In the figure, 10 is a printer, Bd is the main body of the printer 10, and Cs is the housing that constitutes the exterior of the printer 10. The housing Cs comprises a front wall Wf, a back wall Wr, a top wall Wt, a left side wall Ws1 (Figure 17), which is the left side wall of the printer 10 (described later), and a right side wall Ws2. A head holder Ep, which holds the LED head Hd as an exposure device, is pivotably mounted on the top wall Wt. A stacker St1, which serves as an output medium stacking section for loading paper (not shown) on which a color image has been formed, is pivotably mounted on the back wall Wr side of the head holder Ep.

Furthermore, 11Bk, 11C, 11M, and 11Y are a plurality of image forming units (ID units) of black, cyan, magenta, and yellow, respectively, detachably mounted on the main body Bd of the printer 10 from the front wall Wf to the back wall Wr. The LED head Hd is positioned opposite each image forming unit 11Bk, 11C, 11M, and 11Y, facing a photosensitive drum 13, which serves as an image carrier and is rotatably mounted on each unit. The image forming units 11Bk, 11C, 11M, and 11Y constitute the developing unit.

Furthermore, 14 is a paper cassette that serves as a media storage unit for storing paper, and a stacker St2 is provided in the paper cassette 14 as a paper feed media stacking unit for stacking paper.
Furthermore, the paper cassette 14 is rotatably equipped with a hopping roller 15 as a feeding member for feeding paper from within the paper cassette 14, a paper feed roller 16 for sending the fed paper to the main paper transport path Rt1, which serves as both a main medium transport path and a second medium transport path, and a separation roller 17 that contacts the paper feed roller 16 to separate the paper one sheet at a time.

Furthermore, in the figure, m1 is a transport roller set that constitutes a pair of registration rollers for transporting paper supplied from the paper cassette 14 in the main paper transport path Rt1 and correcting its skew, and a pair of transport rollers for transporting paper with an image formed on its surface in the second branch transport path Rt3, which will be described later. The transport roller set m1 consists of a registration roller r1 and pressure rollers r2 and r3 arranged in contact with the registration roller r1. When the registration roller r1 constitutes a pair of registration rollers for correcting the skew of paper supplied from the paper cassette 14, it is rotated counterclockwise in the figure. When it constitutes a pair of transport rollers for transporting paper with an image formed on its surface, it is rotated clockwise in the figure.

Furthermore, m2 is a pair of transport rollers arranged downstream of the transport roller set m1 in the main paper transport path Rt1, and u1 is a transfer unit arranged downstream of the transport roller pair m2 in the main paper transport path Rt1, facing the image forming units 11Bk, 11C, 11M, and 11Y.

The transfer unit u1 comprises a drive roller R1 rotatably disposed below the image forming unit 11Bk, a driven roller R2 rotatably disposed below the image forming unit 11Y, a transfer belt 21 stretched between the drive roller R1 and the driven roller R2 so as to be able to move, and a transfer roller 22 as a transfer member rotatably disposed opposite each photoreceptor drum 13 via the transfer belt 21.

Furthermore, 25 is a fixing unit and fixing device detachably disposed on the main body Bd downstream of the image forming units 11Bk, 11C, 11M, 11Y and the transfer unit u1 in the main paper transport path Rt1. The fixing unit 25 comprises a heating unit 26 as a first fixing member and a backup roller 27 as a second fixing member.

Furthermore, m3 is a pair of discharge rollers arranged downstream of the fuser 25 in the main paper transport path Rt1, and 28 is a separator acting as a media transport guide, swingably arranged downstream of the discharge roller pair m3 in the main paper transport path Rt1. The paper is transported along the main paper transport path Rt1 by the separator 28 and discharged outside the device body Bd, or it is moved to a first branch transport path Rt2, which is a first media transport path formed by branching off from the main paper transport path Rt1, where it is reversed, and then sent to a second branch transport path Rt3, which is formed by branching off from the first branch transport path Rt2.

A pair of discharge rollers m4 is arranged downstream of the separator 28 in the main paper transport path Rt1, and a paper outlet h1, which serves as a media outlet, is formed adjacent to the pair of discharge rollers m4.

Furthermore, a pair of reversing rollers m5 is arranged downstream of the separator 28 in the first branch transport path Rt2, and a pair of reversing rollers m6 is arranged downstream of the pair of reversing rollers m5. When performing double-sided printing, the paper is temporarily moved to the first branch transport path Rt2 by the reversing rollers m5 and m6. In this embodiment, a paper retraction opening h2, serving as a media retraction opening, is formed adjacent to the pair of reversing rollers m6, so that a portion of the paper can protrude from the main body Bd of the device as needed.

The second branch transport path Rt3 is equipped with transport roller pairs m7 to m10 for transporting the inverted paper.

The transport roller set m1, transport roller pairs m2, m7-m10, etc., are rotated by driving a transport motor (not shown) which serves as the first drive unit. In this embodiment, the transport motor can be driven in reverse to rotate the transport roller set m1 in the reverse direction, while the transport roller pairs m2, m7-m10 are left to rotate freely.

Furthermore, the backup roller 27, the discharge roller pair m3, m4, etc., are rotated by driving a fixing motor (not shown) which serves as a second drive unit, while the reversing roller pair m5, m6, etc., are rotated by driving a reversing motor (not shown) which serves as a third drive unit capable of driving in the reverse direction.

Next, the image forming units 11Bk, 11C, 11M, and 11Y will be described.

Figure 3 is a conceptual diagram of an image forming unit in an embodiment of the present invention. Note that image forming units 11Bk, 11C, 11M, and 11Y all have the same structure except for the color of the toner used as the developer; therefore, only image forming unit 11Bk is shown in the figure.

The image forming units 11Bk, 11C, 11M, and 11Y each comprise a main body of the image forming unit 11Bk, 11C, 11M, and 11Y, i.e., a unit body 33, and a toner storage device Ct, which serves as a developer storage device, detachably disposed on each unit body 33.

The toner storage device Ct comprises a toner storage chamber (not shown) which serves as a first developer storage section for storing new toner cartridges of each color (not shown), and a waste toner box Bx (not shown) which serves as a second developer storage section adjacent to the toner storage chamber and for storing waste toner as a discarded developer.

Furthermore, the image forming units 11Bk, 11C, 11M, and 11Y each include, within the unit body 33, the photoreceptor drum 13 rotatably disposed in the direction of arrow A, a charging roller 34 as a charging device rotatably disposed in contact with the photoreceptor drum 13, a developing roller 36 as a developer carrier rotatably disposed in contact with the photoreceptor drum 13, a supply roller 38 as a developer supply member rotatably disposed in contact with the developing roller 36, a developing blade 39 as a developer regulating member disposed in pressure with the developing roller 36, a cleaning blade 41 as a first cleaning member disposed in contact with the photoreceptor drum 13, a transport coil 43 as a waste developer transport member rotatably disposed below the cleaning blade 41 to transport the waste toner to the waste toner box Bx, and a cleaning roller 44 as a second cleaning member disposed in contact with the charging roller 34 to remove toner adhering to the charging roller 34.

The charging roller 34 uniformly charges the surface of the photoreceptor drum 13. A predetermined charging voltage is applied to the charging roller 34. The LED head Hd irradiates the photoreceptor drum 13 with light corresponding to the image signal, and when the uniformly charged surface of the photoreceptor drum 13 is exposed, an electrostatic latent image is formed on the surface of the photoreceptor drum 13.

The developing roller 36 develops the electrostatic latent image formed on the surface of the photoreceptor drum 13 by depositing toner onto it, thereby forming toner images as developer images of each color, which are visible images. A predetermined developing voltage is applied to the developing roller 36.

The supply roller 38 is rotated in the same direction as the developing roller 36, supplying toner from the toner storage chamber to the unit body 33 to the developing roller 36 and simultaneously causing it to become triboelectrically charged. A predetermined supply voltage is applied to the supply roller 38.

The developing blade 39 thins the toner supplied to the developing roller 36 by the supply roller 38, forming a toner layer as a developer layer. A predetermined regulated voltage is applied to the developing blade 39.

The cleaning blade 41 scrapes off toner and other materials remaining on the photoreceptor drum 13 and removes them as waste toner.

Next, the operation of the printer 10 will be described.

In each image forming unit 11Bk, 11C, 11M, and 11Y, the photoreceptor drum 13 is rotated, and the charging roller 34 uniformly charges the surface of the photoreceptor drum 13. Subsequently, the LED head Hd exposes the photoreceptor drum 13, forming an electrostatic latent image on its surface.

Then, the developing roller 36 develops the electrostatic latent image and forms a toner image on the photoreceptor drum 13.

Furthermore, the paper stored in the paper cassette 14 is fed out of the paper cassette 14 by the hopping roller 15, separated one sheet at a time by the feed roller 16 and separation roller 17, and fed into the main paper transport path Rt1. It is then transported by the transport roller set m1 and transport roller pair m2, and sent between the image forming units 11Bk, 11C, 11M, and 11Y and the transfer unit u1. The toner images on each photoreceptor drum 13 are sequentially superimposed and transferred onto the paper, forming a color toner image.

The paper on which the color toner image has been formed is sent to the fuser unit 25. In the fuser unit 25, the toner image on the paper is heated by the heating unit 26 and pressed by the backup roller 27 to fix it to the paper, thereby forming a color image.

In the case of single-sided printing, the paper on which the color image has been formed is transported along the main paper transport path Rt1 by the discharge roller pair m3, then discharged from the paper outlet h1 outside the main unit Bd by the discharge roller pair m4, and loaded onto the stacker St1.

Furthermore, in the case of double-sided printing, the paper with the color image formed on the front surface is transported along the main paper transport path Rt1 by the discharge roller pair m3, then guided to the first branch transport path Rt2 by the separator 28, and retracted to the first branch transport path Rt2 by the reversing roller pair m5 and m6. Once the rear end of the paper passes the separator 28, it is reversed by the reversing roller pair m5 and m6, which are rotated in the opposite direction, and sent to the second branch transport path Rt3. It is then transported along the second branch transport path Rt3 by the transport roller pair m7 to m10, and finally sent back to the main paper transport path Rt1 by the transport roller set m1. Subsequently, an image is formed on the back surface of the paper.

Next, the relationship between the fuser 25, the main paper transport path Rt1, and the first and second branch transport paths Rt2 and Rt3 will be explained.

Figure 4 is a diagram illustrating the relationship between the fuser, the main paper transport path, and the first and second branch transport paths in an embodiment of the present invention. In the figure, the positive X-axis direction is the rear direction in the printer 10, the negative X-axis direction is the front direction in the printer 10, the positive Y-axis direction is the left direction in the printer 10, the negative Y-axis direction is the right direction in the printer 10, the positive Z-axis direction is the upward direction in the printer 10, and the negative Z-axis direction is the downward direction in the printer 10.

In the diagram, Wr is the back wall, Wt is the top wall, Tc is the top cover formed on the top wall Wt, St1 is the stacker, Bd is the main body of the device, 25 is the fuser, Rt1 is the main paper transport path, Rt2 is the first branch transport path, Rt3 is the second branch transport path, 28 is the separator, h1 is the paper exit, and h2 is the paper retraction opening.

The fuser unit 25 comprises a housing Hz, within which the heating unit 26 and backup roller 27 are disposed. The heating unit 26 consists of a fuser belt Hb that is movably disposed, and a heater Ht, which serves as a heat source, disposed within the fuser belt Hb, facing the backup roller 27 via the fuser belt Hb. Furthermore, a handle 29 is formed on the top plate Pt at the top of the housing Hz, projecting upward.

Furthermore, Gu is positioned downstream of the fuser 25 in the paper transport direction (rearward of the fuser 25 within the device body Bd (positive X-axis direction)), and forms the main paper transport path Rt1 and the first branch transport path Rt2, serving as a guide unit for guiding the paper.

The guide unit Gu comprises a discharge guide 45 having an arched shape, an intermediate guide 46 having an arched shape and formed behind the discharge guide 45 to cover the back surface of the discharge guide 45, and a reversal guide 47 having a concave shape and formed behind the intermediate guide 46 to cover the back surface of the intermediate guide 46. The discharge guide 45, intermediate guide 46, and transfer guide 47 are arranged to open and close relative to each other. A main paper transport path Rt1 is formed between the discharge guide 45 and the intermediate guide 46, and a first branch transport path Rt2 is formed between the intermediate guide 46 and the reversal guide 47.

Furthermore, the intermediate guide 46 is arranged to be movable relative to the discharge guide 45, and in this embodiment, it is arranged to be swingable. The discharge guide 45 and the intermediate guide 46 are also arranged to be movable relative to the reversing guide 47, and in this embodiment, they are arranged to be swingable.

Furthermore, the discharge guide 45 constitutes the first guide, the intermediate guide 46 constitutes the second guide, the reversal guide 47 constitutes the first media guide, and the discharge guide 45 and intermediate guide 46 constitute the second media guide.

The main paper transport path Rt1 is equipped with a fuser 25, discharge roller pairs m3 and m4, a separator 28, etc. The first branch transport path Rt2 is equipped with reversing roller pairs m5 and m6, etc. The second branch transport path Rt3 is equipped with transport roller pairs m7 to m10. Near the paper outlet h1 on the top wall Wt, a regulating plate 49 is installed, with an adjustable mounting angle, to restrict the direction in which the paper is discharged outside the main body Bd of the device.

In this embodiment, since the fuser 25 is detachably mounted to the main body Bd, when a paper jam occurs in the fuser 25 (a media jam of paper on which an image has been formed), the top cover Tc formed on the back wall Wr side of the top wall Wt can be opened to remove the fuser 25 from the main body Bd in order to remove the paper or to perform maintenance on the fuser 25.

However, as shown in Figure 4, the regions indicated by the arrows in the main paper transport path Rt1 and the regions indicated by the arrows in the first branch transport path Rt2 both have small radii of curvature. Therefore, if a paper jam occurs in these regions of the main paper transport path Rt1 and the first branch transport path Rt2, it is not possible to remove the paper reliably and easily.

Therefore, in this embodiment, by utilizing the space created by removing the fuser 25 from the main body Bd of the device, the discharge guide 45 and the intermediate guide 46 are separated from the reversing guide 47, thereby opening the first branch transport path Rt2 and removing the jammed paper from the first branch transport path Rt2. Alternatively, by separating the intermediate guide 46 from the discharge guide 45, the main paper transport path Rt1 is opened, allowing the jammed paper to be removed from the main paper transport path Rt1.

Figure 1 is a cross-sectional view of the main part of the printer in an embodiment of the present invention, Figure 5 is a perspective view of the guide unit in an embodiment of the present invention, Figure 6 is a perspective view of the discharge guide and intermediate guide viewed from the front left in an embodiment of the present invention, Figure 7 is a perspective view of the discharge guide and intermediate guide viewed from the front right in an embodiment of the present invention, Figure 8 is a perspective view of the intermediate guide viewed from the front left in an embodiment of the present invention, Figure 9 is a perspective view of the intermediate guide viewed from the front right in an embodiment of the present invention, Figure 10 is a perspective view of the main part of the intermediate guide viewed from the front left in an embodiment of the present invention, and Figure 11 is a perspective view of the reversing guide viewed from the front left in an embodiment of the present invention. Note that in Figures 5 to 11, 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.

In the diagram, 10 is the printer, 25 is the fuser, Gu is the guide unit, 45 is the ejection guide, 46 is the intermediate guide, 47 is the reversal guide, Rt1 is the main paper transport path, Rt2 is the first branch transport path, Rt3 is the second branch transport path, m3 and m4 are the ejection roller pair located on the main paper transport path Rt1, m5 and m6 are the reversal roller pair located on the first branch transport path Rt2, and m7 and m8 are the transport roller pair located on the second branch transport path Rt3.

The discharge roller pair m3, m4 and the reversing roller pair m5, m6 each comprise a shaft portion sha, multiple rubber drive rollers ra arranged at various locations on the shaft portion sha, and driven rollers rb arranged in contact with each of the drive rollers ra.

Furthermore, the conveyor roller pair m7 and m8 comprises a shaft portion (not shown), rubber drive rollers ra arranged at multiple locations on the shaft portion, and driven rollers rb arranged in contact with each of the drive rollers ra.

Furthermore, in the diagram, LF is the left fixed frame, RF is the right fixed frame, Lf is the left opening/closing frame pivotably mounted relative to the fixed frame LF, and Rf is the right opening/closing frame pivotably mounted relative to the fixed frame RF.

The aforementioned fixed frames LF and RF are attached to the back wall Wr (Figure 2) by flange fg1, holding both the left and right ends of the reversal guide 47, and supporting the opening and closing frames Lf and Rf so as to be pivotable relative to the device body Bd.

To achieve this, posts ps are formed at predetermined locations on the fixed frames LF and RF, facing each other and protruding. Holes, specifically through-holes ha, are formed at predetermined locations on the opening/closing frames Lf and Rf, at the front lower ends in this embodiment. The posts ps and through-holes ha engage; in this embodiment, the posts ps are fitted into the through-holes ha.

Furthermore, an arc-shaped through groove ma is formed at a predetermined location in the opening/closing frames Lf and Rf, above the through hole ha in this embodiment. The shaft portion of the conveyor roller pair m7 passes through this through groove ma. This allows the opening/closing frames Lf and Rf to slide relative to the fixed frames LF and RF by the length of the through groove ma.

Furthermore, the shaft portion sha of the discharge roller pair m3 and m4, the drive roller ra, and the driven roller rb are rotatably supported by the opening and closing frames Lf and Rf. The shaft portion sha and the drive roller ra of the reversing roller pair m5 and m6 are rotatably supported by the reversing guide 47, and the driven roller rb of the reversing roller pair m5 and m6 is rotatably supported by the intermediate guide 46.

Furthermore, locking members (not shown) are provided between the fixed frames LF and RF and the opening/closing frames Lf and Rf.

When the operator rotates the opening/closing frames Lf and Rf counterclockwise in the direction shown in Figure 5 and locks the locking member, the opening/closing frames Lf and Rf are placed in the upright position as the first state shown in Figure 6. This positions the discharge guide 45 and intermediate guide 46 opposite the reversing guide 47, closing the gap between the intermediate guide 46 and the reversing guide 47, and forming the first branched transport path Rt2. At this time, the shaft portion of the transport roller pair m7 is brought into contact with the upper end eg1 of the through groove ma, thereby restricting the rotation of the opening/closing frames Lf and Rf.

Then, when the operator releases the locking member and rotates the opening/closing frames Lf and Rf clockwise and tilts them forward, the opening/closing frames Lf and Rf are placed in a second inclined state. This places the discharge guide 45 and intermediate guide 46 into the space SP (Figure 15), which will be described later. The space between the intermediate guide 46 and the reversing guide 47 is opened, and the first branching transport path Rt2 is opened. At this time, the shaft portion of the transport roller pair m7 is brought into contact with the lower end eg2 of the through groove ma, thereby restricting the rotation of the opening/closing frames Lf and Rf.

Furthermore, the opening and closing frames Lf and Rf hold both the left and right ends of the discharge guide 45, pivotably support the intermediate guide 46 relative to the opening and closing frames Lf and Rf, and switchably support the separator 28.

To achieve this, holes hb are formed at the lower ends of the blocks 52 formed at both the left and right ends of the intermediate guide 46, and posts (not shown) are formed at locations corresponding to the holes hb in the opening/closing frames Lf and Rf, and these posts are engaged with the holes hb.

When the operator places the opening/closing frames Lf, Rf, discharge guide 45, and intermediate guide 46 in an inclined position, and rotates the intermediate guide 46 counterclockwise, separating it from the discharge guide 45, the gap between the discharge guide 45 and the intermediate guide 46 opens, opening the main paper transport path Rt1. When the operator rotates the intermediate guide 46 clockwise, the gap between the discharge guide 45 and the intermediate guide 46 closes, forming the main paper transport path Rt1.

On the fixed frame LF, a gear train Gt1, pulleys py1 to py3, and belts bt1, bt2, etc., consisting of a timing belt, are arranged to transmit the rotation of the reversing motor to the reversing roller pair m5 and m6. Pulley py2 is attached to one end of the shaft portion sha of the reversing roller pair m5, and pulley py3 is attached to one end of the shaft portion sha of the reversing roller pair m6.

Furthermore, pulleys py4 and py5, and a belt bt3 consisting of a timing belt, etc., are arranged on the opening/closing frame Lf to transmit the rotation of the discharge roller pair m3 to the discharge roller pair m4. Pulley py4 is attached to one end of the shaft portion sha of the discharge roller pair m3, and pulley py5 is attached to one end of the shaft portion sha of the discharge roller pair m4.

Furthermore, the opening/closing frame Rf is equipped with a gear gr1 that constitutes a gear train Gt2 for transmitting the rotation of the fixing motor to the discharge roller pair m3 and m4, and this gear gr1 is attached to one end of the shaft portion sha of the discharge roller pair m3.

Next, the support structures for the discharge roller pair m3, m4 and the reversing roller pair m5, m6 will be described.

Figure 12 is a perspective view showing the support structure for the discharge roller pair and the reversing roller pair in an embodiment of the present invention.

In the diagram, m3 and m4 are discharge roller pairs, m5 and m6 are reversing roller pairs, 45 is a discharge guide, 46 is an intermediate guide, 47 is a reversing guide, RF is a fixed frame, and Rf is an opening/closing frame.

Each discharge roller pair m3 and m4 consists of a shaft portion sha, a drive roller ra, and a driven roller rb. The shaft portion sha and the drive roller ra are attached to the opening/closing frames Lf and Rf (Figure 6), while the driven roller rb is attached to the discharge guide 45.

Furthermore, each of the reversing roller pairs m5 and m6 consists of a shaft portion sha (Figures 1 and 11), a drive roller ra, and a driven roller rb. The shaft portion sha and drive roller ra are attached to the reversing guide 47, while the driven roller rb is attached to the intermediate guide 46.

Next, we will describe the state of the guide unit Gu when the opening and closing frames Lf and Rf are placed in the upright and inclined positions, as well as the rotational transmission system of the discharge roller pair m3 and m4 and the reversing roller pair m5 and m6.

Figure 13 is a first diagram showing the rotational transmission system when the opening/closing frame in an embodiment of the present invention is placed in an upright position. Figure 14 is a second diagram showing the rotational transmission system when the opening/closing frame in an embodiment of the present invention is placed in an upright position. Figure 15 shows the state of the guide unit when the opening/closing frame in an embodiment of the present invention is placed in an inclined position. Figure 16 shows the rotational transmission system when the opening/closing frame in an inclined position is placed in an embodiment of the present invention.

In the diagram, Bd is the main body of the device, Gu is the guide unit, and SP is the space formed in front of the guide unit Gu when the fuser 25 (Figure 2) is removed from the main body Bd of the device.

The discharge guide 45, intermediate guide 46, and reversing guide 47 are arranged to be openable and closable relative to each other. The discharge guide 45 and intermediate guide 46 form a main paper transport path Rt1 for transporting paper and discharging it outside the device body Bd, while the intermediate guide 46 and reversing guide 47 form a first branch transport path Rt2 for transporting and reversing paper.

Furthermore, in the figure, LF and RF are fixed frames, Lf and Rf are opening/closing frames, Gt2 is a gear train, m3 and m4 are discharge roller pairs, m5 and m6 are reversing roller pairs, m7 is a conveying roller pair, and ma is a through groove. The discharge roller pairs m3 and m4 and the reversing roller pairs m5 and m6 each include a shaft portion sha, a drive roller ra, and a driven roller rb, while the conveying roller pair m7 includes a shaft portion (not shown), a drive roller ra, and a driven roller rb.

The shaft portions sha of the discharge roller pairs m3 and m4 extend through the opening and closing frames Lf and Rf. On the opening and closing frame Lf, pulley py4 is attached to the end of the shaft portion sha of the discharge roller pair m3, and pulley py5 is attached to the end of the shaft portion sha of the discharge roller pair m4. On the opening and closing frame Rf, gear gr1 is attached to the end of the shaft portion sha of the discharge roller pair m3, and gear gr2 is arranged to mesh with gear gr1.

Furthermore, gear gr3 is arranged on the fixed frame RF, meshing with the downstream gear of the gear train Gt2.

When the opening/closing frames Lf and Rf are placed in an upright position, gear gr2 on the opening/closing frame Rf and gear gr3 on the fixed frame RF mesh together. The rotation of the fixing motor is transmitted to the discharge roller pair m3 via the gear train Gt2, gear gr3, gear gr2, and gear gr1, causing the discharge roller pair m3 to rotate. When the discharge roller pair m3 rotates, pulley py4 on the opening/closing frame Lf rotates, belt bt3 moves, pulley py5 rotates, the rotation of pulley py5 is transmitted to the discharge roller pair m4, causing the discharge roller pair m4 to rotate.

Furthermore, when the opening/closing frames Lf and Rf are placed in an inclined position, the engagement between gear gr2 on the opening/closing frame Rf and gear gr3 on the fixed frame RF is disengaged, allowing the discharge roller pairs m3 and m4 to rotate freely.

Next, we will explain the procedure for removing paper from the first branch transport path Rt2 when a paper jam occurs in the first branch transport path Rt2.

Figure 17 is a perspective view of the main part of the printer illustrating the first procedure for removing paper from the first branch transport path in an embodiment of the present invention; Figure 18 is a cross-sectional view of the main part of the printer illustrating the first procedure for removing paper from the first branch transport path in an embodiment of the present invention; Figure 19 is a perspective view of the main part of the printer illustrating the second procedure for removing paper from the first branch transport path in an embodiment of the present invention; Figure 20 is a cross-sectional view of the main part of the printer illustrating the second procedure for removing paper from the first branch transport path in an embodiment of the present invention; Figure 21 is a perspective view of the main part of the printer illustrating the third procedure for removing paper from the first branch transport path in an embodiment of the present invention; and Figure 22 is a cross-sectional view of the main part of the printer illustrating the third procedure for removing paper from the first branch transport path in an embodiment of the present invention.

In the diagram, 10 is the printer, Wr is the back wall, Ws1 is the left side wall when the printer 10 is viewed from the front, Ws2 is the right side wall when the printer 10 is viewed from the front, Wt is the top wall, St1 is the stacker, 25 is the fuser, 29 is the handle, Gu is the guide unit, Lf and Rf are the opening and closing frames, 45 is the discharge guide, 46 is the intermediate guide, 47 is the reversing guide, Rt1 is the main paper transport path, Rt2 is the first branch transport path, and m4 is the discharge roller pair.

As shown in Figures 17 and 18, when the operator opens the top cover Tc formed on the back wall Wr side of the top wall Wt, grasps the handle 29, and removes the fuser 25 from the main body Bd of the device via the outlet Hex, a space SP is formed in front of the guide unit Gu, as shown in Figures 19 and 20. At this time, the opening/closing frames Lf and Rf, the discharge guide 45, and the intermediate guide 46 are in an upright position.

Next, when the operator places the opening/closing frames Lf and Rf in an inclined position and places the discharge guide 45 and intermediate guide 46 in space SP, the first branch transport path Rt2 is opened, as shown in Figures 21 and 22. This allows the operator to remove the jammed paper in the first branch transport path Rt2.

In this case, in the first branching transport path Rt2, the pair of drive rollers ra and driven roller rb forming the reversing roller pair m5, m6 and the transport roller pair m7 are separated. Therefore, the paper is not pinched between the drive rollers ra and driven rollers rb, and the paper can be easily removed.

Next, we will explain the procedure for removing paper from the main paper transport path Rt1 when a paper jam occurs in the main paper transport path Rt1. Note that the procedure for removing paper from the main paper transport path Rt1 when a paper jam occurs is the same as the first procedure for removing paper from the first branch transport path Rt2 shown in Figures 17 and 18, through to the third procedure shown in Figures 21 and 22. Therefore, we will omit the explanation of these steps and only explain the fourth procedure for removing paper from the main paper transport path Rt1.

Figure 23 is a perspective view of the main part of the printer illustrating the fourth step in removing paper from the main paper transport path in an embodiment of the present invention, and Figure 24 is a cross-sectional view of the main part of the printer illustrating the fourth step in removing paper from the main paper transport path in an embodiment of the present invention.

In the diagram, 10 is the printer, 45 is the discharge guide, 46 is the intermediate guide, Lf and Rf are the opening/closing frames, and m3 and m4 are the discharge roller pair.

As shown in Figures 23 and 24, with the opening and closing frames Lf and Rf in an inclined position, and the discharge guide 45 and intermediate guide 46 positioned within the space SP (Figure 20), the operator rotates the intermediate guide 46 counterclockwise in the diagram, separating it from the discharge guide 45. This opens the main paper transport path Rt1 (Figure 1), allowing the operator to remove the jammed paper in the main paper transport path Rt1.

At this time, the drive roller ra and driven roller rb of the discharge roller pair m3 and m4 are in contact with each other. However, as shown in Figure 16, the engagement between gear gr2 on the opening/closing frame Rf and gear gr3 on the fixed frame RF is disengaged, so the discharge roller pair m3 and m4 are allowed to rotate freely.

Thus, in this embodiment, since the first branch transport path Rt2 can be opened with the discharge guide 45 and intermediate guide 46 positioned within the space SP, even if a paper jam occurs in the first branch transport path Rt2 due to paper on which an image has been formed, the paper can be reliably and easily removed.

Therefore, the space SP formed within the device body Bd when the fuser unit 25 is removed from the device body Bd can be effectively utilized.

Furthermore, by simply opening the top cover Tc, the jammed paper can be removed without opening the back wall Wr, left wall Ws1, right wall Ws2, etc. This not only reduces the workspace required for paper removal, but also simplifies the operation by eliminating the need for the operator to move the printer 10 to create workspace.

In this embodiment, four image forming units 11Bk, 11C, 11M, and 11Y are arranged, and a toner image is formed on the paper being transported between each image forming unit 11Bk, 11C, 11M, and 11Y and the transfer unit u1. However, the present invention can also be applied to printers that use an intermediate transfer belt running between each image forming unit 11Bk, 11C, 11M, and 11Y and the transfer unit u1, forming a toner image on the intermediate transfer belt and transferring it to the paper, or to printers with a single image forming unit.

In this embodiment, a printer 10 was described, but the present invention can be applied to image forming devices such as photocopiers, facsimile machines, and multifunction printers.

Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible based on the spirit of the invention; these modifications do not exclude the scope of the present invention.

10 Printer 25 Fuser 45 Discharge guide 46 Intermediate guide 47 Reversal guide Bd Device body Gu Guide unit Rt2 First branch transport path SP Space

Claims (6)

(a) A fixing device detachably mounted to the main body of the device,
(b) Having a guide unit disposed downstream of the fixing device in the medium transport direction and guiding the medium,
(c) The guide unit comprises a first media guide and a second media guide that is movably disposed relative to the first media guide.
(d) When the fixing device is removed from the main body of the device, a space is formed inside the main body of the device.
(e) An image forming apparatus characterized in that the second media guide is positioned opposite the first media guide, forming a first media transport path between it and the first media guide, and the first media transport path is opened while the second media guide is placed in the space. (a) The second media guide comprises a first guide and a second guide that is movably disposed relative to the first guide,
(b) With the second media guide positioned opposite the first media guide, the first media transport path is formed between the first media guide and the second guide, and the second media transport path is formed between the first and second guides.
(c) The image forming apparatus according to claim 1, wherein the second medium guide is placed in the space and the first and second medium transport paths are opened with the second guide separated from the first medium guide. (a) The device has an opening/closing frame that is pivotably supported with respect to a fixed frame attached to the main body of the device and can be placed in a first and second state,
(b) The first media guide is held by the fixed frame,
(c) The opening and closing frame holds the second media guide,
(d) When the opening/closing frame is placed in the first state, the first medium transport path is formed.
(e) The image forming apparatus according to claim 1, wherein the first medium transport path is opened when the opening/closing frame is placed in the second state. (a) The second media guide comprises a first guide and a second guide that is movably disposed relative to the first guide,
(b) The image forming apparatus according to claim 3, wherein the second guide is pivotably supported with respect to the opening and closing frame. (a) A pair of reversing rollers for reversing the medium is provided in the first medium transport path,
(b) The image forming apparatus according to claim 4, wherein when the opening and closing frame is placed in the second state, the pair of rollers forming the reversing roller pair are separated. (a) A second medium transport path is formed between the first and second guides,
(b) A pair of discharge rollers for discharging the medium is provided in the second medium transport path,
(c) The image forming apparatus according to claim 4, wherein the discharge roller pair is made to rotate freely when the opening and closing frame is placed in the second state.