JP4085707B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus using a so-called electrophotographic system for transferring a toner image formed on an image carrier such as a photosensitive drum or an intermediate transfer member onto a recording sheet. The present invention relates to an improvement in an image forming apparatus of a type that allows a user to perform the replacement by the user's own hand without the intervention of a specialized service engineer.
[0002]
[Prior art]
Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a laser printer, after a toner image corresponding to image information is formed on a photosensitive drum, the toner image is directly transferred from the photosensitive drum to a recording sheet, Alternatively, the recording image is formed by indirectly transferring to a recording sheet via an intermediate transfer member, and fixing the transferred toner image to the recording sheet by heating. In particular, in a color copying machine or a color printer that requires superposition of a plurality of color toner images, a plurality of toners are transferred onto the belt by repeatedly transferring the toner image from the photosensitive drum to the intermediate transfer member. Many methods using such an intermediate transfer member have been proposed because image alignment can be performed.
[0003]
Further, as a means for transferring a toner image from an image carrier such as a photosensitive drum or an intermediate transfer member to a recording sheet, a transfer bias having a polarity opposite to the charging polarity of the toner has been recently used from the viewpoint of reducing environmental load due to the generation of ozone. The applied transfer roll is frequently used. This transfer roll is formed by covering the periphery of a conductive shaft member with a semiconductive elastic layer, presses the image carrier with a predetermined urging force, and a recording sheet is inserted therebetween. It is configured as follows. Thus, the recording sheet passes in a nipped state between the transfer roll and the image carrier, and the toner image is formed on the image carrier by the electric field formed by the transfer bias and the pressure accompanying the pressure contact of the transfer roll. It is transferred from the surface to the recording sheet.
[0004]
[Problems to be solved by the invention]
By the way, in this type of image forming apparatus, in order to improve the maintenance property of the photosensitive drum and the intermediate transfer member and to facilitate the replacement thereof, unitization of these image carriers is being promoted. As described above, the image forming apparatus can be freely attached to and detached from the apparatus frame.
[0005]
However, in order to transfer the toner image from the image carrier to the recording sheet, in a state where the image forming unit is mounted on the apparatus frame, the transfer roll is in pressure contact with the image carrier, and the image is kept as it is. If the forming unit is pulled out from the apparatus frame, the surface of the image carrier is damaged by rubbing against the transfer roll.
[0006]
In consideration of such damage of the image carrier, an image forming apparatus configured to attach and detach the image forming unit after forming a gap between the transfer roll and the image carrier has also been proposed. There has been a problem that the image carrier is damaged due to misunderstanding of the operation procedure of the user.
[0007]
The present invention has been made in view of such problems, and an object of the present invention is to completely prevent a user's erroneous operation when the image forming unit is attached to or detached from the apparatus frame, and the user can easily perform the operation. An object of the present invention is to provide an image forming apparatus capable of attaching and detaching an image forming unit by operation.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the image forming apparatus of the present invention inserts a recording sheet between an image carrier and a transfer member that are in contact with each other, and uses the toner image formed on the image carrier as a recording sheet. On the premise of an image forming apparatus configured to transfer, the transfer member is provided so as to be able to come into contact with and separate from the image carrier, while the image carrier is mounted on an image forming unit that is detachable from the apparatus frame. The image forming unit is allowed to be attached to and detached from the apparatus frame on the condition that the transfer member is set at a retracted position separated from the image carrier.
[0009]
The term “detachable” as used herein refers to the attachment / detachment of the image forming unit to / from the image forming position, and the image forming unit is completely separated from the apparatus frame in addition to the form in which the image forming unit is completely removed from the apparatus frame. It also includes a form drawn out from the image forming position.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a full-color laser beam printer to which the present invention is applied. This printer is a so-called tandem type color printer having four photosensitive drums 1Y, 1M, 1K, and 1C corresponding to the respective colors of yellow (Y), magenta (M), black (K), and cyan (C). Thus, a toner image corresponding to image information for each color is formed on each photosensitive drum 1 at a predetermined timing. The toner images formed on the photosensitive drums 1Y, 1M, 1K, and 1C are primarily transferred to the first intermediate transfer drums 2a and 2b, and then transferred from the first intermediate transfer drums 2a and 2b to the second intermediate transfer drum. 2 and finally transferred by the final transfer roll 4 in contact with the second intermediate transfer drum 3 from the second intermediate transfer drum 3 to the recording sheet P.
[0011]
A toner image is formed on each of the photosensitive drums 1Y, 1M, 1K, and 1C by a known electrophotographic process. That is, the photosensitive drum 1Y, 1M, 1K, 1C is exposed with the light beam Bm emitted from the raster scanning device 11 after the photosensitive drum is uniformly charged to a predetermined background portion potential by the charging roll 10, and the image information is displayed. An electrostatic latent image corresponding to the above is formed on the photosensitive drum. Then, the electrostatic latent image is developed with toner by the developing device 12 to form a toner image in which the electrostatic latent image is visualized on the photosensitive drum. In the figure, reference numeral 13 denotes a cleaner for cleaning the surfaces of the photosensitive drums 1Y, 1M, 1K, and 1C after the toner images are transferred to the first intermediate transfer drums 2a and 2b.
[0012]
Two first intermediate transfer drums 2 are provided, one for each of the two color photosensitive drums, and one of the first intermediate transfer drums 2a is composed of yellow and magenta photosensitive drums. The toner image is transferred, the toner image is transferred from the black and cyan photosensitive drums to the other first intermediate transfer drum 2a, and the two color toner images are superimposed on each of the first intermediate transfer drums 2a and 2b. It has come to be. The second intermediate transfer drum 3 is in contact with both the pair of first intermediate transfer drums 2a and 2b. After the yellow and magenta toner images are transferred from the first intermediate transfer drum 2a, The black and cyan toner images are transferred from the other first intermediate transfer drum 2 b, and the four color toner images overlap on the second intermediate transfer drum 3.
[0013]
Therefore, in the printer of this embodiment, the toner images of the respective colors are transferred from the photosensitive drums 1Y, 1M, 1K, and 1C to the recording sheet P from the rotation direction of the first intermediate transfer drums 2a and 2b and the second intermediate transfer drum 3. The process distance until the final transfer position is reached in the order of black K, cyan C, yellow Y, and magenta M, and these four color toner images are superimposed on the second intermediate transfer drum 3. In this case, the toner image writing timing on the magenta photosensitive drum 1M is the earliest.
[0014]
On the other hand, the recording sheet P is unloaded from the paper feed cassette 20 by the paper feed roll 21, and is sent to the final transfer position of the toner image on which the final transfer roll 4 is disposed via the transport roll 22 and the registration roll 23. The final transfer roll 4 is configured by providing an elastic layer with adjusted resistivity around a conductive shaft new member, and press-contacts the second intermediate transfer drum 3 to form a nip region having a predetermined width. When the recording sheet P passes through the nip region, the toner image is transferred by an electric electrostatic attraction force and a mechanical pressure contact force. The recording sheet P onto which the toner image is finally transferred is fixed to the toner image through the heating and fixing device 5, and then discharged to the paper discharge tray 26 provided on the upper portion of the printer housing 25 through the exit roll 24. The
[0015]
Among the constituent members described above, the photosensitive drums 1Y, 1M, 1K, and 1C for each color, the charging roll 10, the cleaner 13, the first intermediate transfer drums 2a and 2b, and the second intermediate transfer drum 3 are a single process. The unit 6 is integrated. For example, when the image quality is deteriorated due to deterioration of the photosensitive drum 10, the process unit 6 is replaced as it is. This process unit is supported by two linear guides 60 and 61 located above and below, and when exchanging, by opening the front door shown in the figure, the front side of the printer housing 25 (in FIG. 1). It is configured such that it is pulled out to the front side of the paper and pulled out as it is.
[0016]
FIG. 2 shows a state where various covers covering the printer housing 25 are removed and the printer apparatus frame 27 is exposed. As shown in this figure, the process unit 6 can be freely replaced by being pulled out to the front side of the apparatus frame 27, and can be pushed into the apparatus frame 27 and set at a predetermined position. Yes. A lock lever 63 is provided on the front panel 62 of the process unit 6. By operating the lever 63, the process unit 6 can be removed from the apparatus frame 27. Positioning at a predetermined position in the frame 27 is possible. Since FIG. 2 shows a state in which the process unit 6 is pulled out from the apparatus frame 27, the lock lever 63 is set to the unlocking position.
[0017]
On the other hand, as shown in FIG. 3, in order to facilitate the jam processing of the recording sheet P in this printer, the jam processing cover 40 is configured to open and close so as to divide the conveyance path of the recording sheet P. . The jam processing cover 40 opens and closes around a hinge portion 41 provided on the lower left side of the printer casing 27. When the jam processing cover 40 is opened, the transport path of the recording sheet P from the transport roll 22 to the fixing device 5 is opened. The conveyance path of the recording sheet P from the fixing device 5 to the exit roll 24 is opened, and the recording sheet P existing in the conveyance path from the paper feed roll 21 to the exit roll 24 can be easily removed. ing.
[0018]
The final transfer roll 4 is mounted on the jam processing cover 40, and is in pressure contact with the second intermediate transfer drum 3 with the jam processing cover 40 closed (the state shown in FIG. 1), while being open (see FIG. 3). In the state shown), the second intermediate transfer drum 3 is separated.
[0019]
When the jam processing cover 40 is closed, the second intermediate transfer drum 3 and the final transfer roll 4 are in pressure contact with each other. When the process unit 6 is pulled out from the apparatus frame 27 in this state, the second intermediate transfer drum 3 and the final transfer roll 4 are moved. Since the surface of the transfer roll 4 may be damaged, it is necessary to first open the jam processing cover 40 when the process unit 6 is pulled out from the apparatus frame 27. However, if the user replaces the process unit 6 for convenience, the user may pull out the process unit 6 without opening the jam processing cover 40 due to mistakes. Further, a trouble that the process unit 6 is mounted on the apparatus frame 27 with the jam processing cover 40 closed is also assumed.
[0020]
Therefore, in the printer of this embodiment, the process unit 6 cannot be pulled out from the apparatus frame 27 unless the jam processing cover 40 is opened, in other words, unless the final transfer roll 4 is separated from the second intermediate transfer drum 3. It is configured. On the contrary, unless the process unit 6 is mounted at a predetermined position on the apparatus frame 27, the jam processing cover 40 cannot be closed.
[0021]
FIG. 4 shows this erroneous operation prevention mechanism, and shows a state where the process unit 6 is pushed into the apparatus frame 27. A stopper mechanism 50 for controlling the closing of the jam processing cover 40 is provided at the left end of the front side of the apparatus frame 27, and this stopper mechanism 50 corresponds to the set position of the lock lever 63 of the process unit 6. 40 occlusions are allowed or prevented.
[0022]
FIG. 5 shows the stopper mechanism 50. The stopper mechanism 50 has a casing 51 fixed to the left end of the device frame 27 and a stopper pin 52 that penetrates the casing 51. The stopper pin 52 advances and retreats in the casing 51. The casing 51 protrudes from either one of the left and right ends. Since the casing 51 of the stopper mechanism 50 is located at the left end of the apparatus frame 27, when the jam processing cover 40 is closed, the stopper pin 52 is pushed by the jam processing cover 40 and slides and protrudes from the right end of the casing 51. The first position (the two-dot chain line position in FIG. 5) is set. Further, the stopper pin 52 is urged by a spring (not shown) provided in the casing 51 in a direction to open the jam processing cover 40, that is, in the left direction in FIG. 5, and the jam processing cover 40 is released from the apparatus frame 27. Then, the stopper pin 52 is set to the 2nd position (solid line position in FIG. 5) which protruded from the left end of the casing 51. FIG. That is, the setting position of the stopper pin 52 changes according to the opening / closing of the jam handling cover 40.
[0023]
The casing 51 of the stopper mechanism 50 is provided with a stopper lock member 53 that locks the setting of the stopper pin 52 to the first position. The stopper lock member 53 is formed in a substantially L shape, and is pivotably connected to the casing 51 with the support shaft 54 as a center, and is located at a position covering the casing 51 (a solid line position shown in FIG. 5). ) Covers the end of the stopper pin 52 set at the second position, and the movement of the stopper pin 52 from the second position to the first position is locked. The stopper lock member is always set to the stopper pin locking position (solid line position in FIG. 5) by a spring provided around the support shaft 54.
[0024]
On the other hand, FIG. 6 shows the relationship between the lock lever 63 of the process unit 6 and the stopper mechanism 50. The lock lever 63 provided in the process unit 6 is provided so as to be swingable about the operating shaft 64. When the lock lever 63 is set at a release position indicated by a solid line in the drawing, the process unit 6 is moved relative to the apparatus frame 27. The positioning state is released, and the process unit 6 can be removed from the apparatus frame 27 as shown in FIG. Further, when the lock lever 63 is set at the lock position indicated by a two-dot chain line in the drawing with the process unit 6 pushed into the apparatus frame 27, the process unit 6 is completely pushed into the apparatus frame 27 and positioned. The process unit 6 cannot be removed from the apparatus frame 27 unless the lock lever 63 is set to the release position.
[0025]
Further, a plate-like connecting piece 65 is provided at the rocking end of the lock lever 63. When the lock lever 63 is set from the release position (solid line position) to the lock position (two-dot chain line position), the connecting piece 65 is provided. Is caught on the stopper lock member 53 of the stopper mechanism 50, and the stopper lock member 53 is lifted. As shown in FIG. 5, the stopper lock member 53 is formed in a substantially L-shape having a hollow portion by bending a metal plate formed on the left and right sides, and swings the lock lever 63 to the lock position. At this time, the connecting piece 65 enters the hollow portion of the stopper lock member 53 to lift the stopper lock member 53. As a result, the stopper lock member 53 is retracted from the locking position of the stopper pin 52, and the stopper pin 52 can be set from the first position indicated by the solid line to the first position indicated by the two-dot chain line.
[0026]
Further, when the stopper pin 52 is set to the first position indicated by the two-dot chain line, the tip of the stopper pin 52 protrudes within the swinging range of the connecting piece 65 of the lock lever 63, thereby preventing the lock lever 63 from swinging. It is configured as follows. Therefore, when the stopper pin 52 is set to the first position after the lock lever 63 is set to the lock position, the lock lever 63 is set to the release position unless the stopper pin 52 is set to the second position indicated by the solid line. It is something that cannot be redone.
[0027]
Next, the movement of the stopper mechanism 50 will be described with the opening / closing of the jam processing cover 40 and the replacement operation of the process unit 6.
First, it is assumed that the process unit 6 is mounted in the apparatus frame 27, the lock lever 63 is set to the lock position, and the jam processing cover 40 is closed. Since the jam processing cover 40 is closed, at this time, the stopper pin 52 is pressed by the jam processing cover 40 and set to the first position indicated by a two-dot chain line. Further, since the lock lever 63 of the process unit 6 is set at the lock position, the connecting piece of the lock lever 63 pushes up the stopper lock member 53, and the stopper lock member 53 moves the stopper pin 52 to the first position. It is lifted to a position that does not interfere with the setting.
[0028]
In order to replace the process unit 6 from this state, first, the jam handling cover 40 is opened from the closed position indicated by the two-dot chain line in FIG. 6 to the position indicated by the solid line. Accordingly, the stopper pin 52 biased by the spring slides from the first position to the second position (solid line position) in conjunction with the opening of the jam processing cover 40. Then, when the stopper pin 52 moves from the first position to the second position, the lock lever 63 can be operated from the lock position to the release position. When the jam processing cover 40 is not opened, the stopper pin 52 is set at the first position. Therefore, the stopper pin 52 prevents the lock lever 63 from swinging, and the lock lever 63 is released from the lock position. Cannot be set.
[0029]
That is, in this printer, unless the jam processing cover 40 is opened, the lock lever 63 cannot be turned to the release position, and as a result, the process unit 6 cannot be extracted from the apparatus frame 27. As a result, when the final transfer roll 4 is in pressure contact with the second intermediate transfer drum 3, the second intermediate transfer drum 3 cannot be pulled out together with the process unit 6, and the user can remove the final transfer roll 4 and the second intermediate transfer drum from each other. An erroneous operation such as replacement of the process unit 6 without releasing the pressure contact state with the drum 3 can be avoided.
[0030]
As shown in FIG. 4, a peripheral wall 28 of the apparatus frame 27 is provided between the stopper mechanism 50 and the lock lever 63 of the process unit 6, and the connecting piece 65 of the lock lever 63 is connected to the peripheral wall 28. The stopper lock member 53 of the stopper mechanism 50 is engaged through the opened slit-shaped opening 29. That is, when the lock lever 63 is set to the lock position, the connecting piece 65 is inserted into the opening 29 of the peripheral wall 28. Therefore, in the state where the lock lever 63 is set to the lock position, even if the process unit 6 is to be extracted from the apparatus frame 27, the connecting piece 65 interferes with the peripheral wall 28, and the process unit 6 cannot be extracted. It is in a state. As a result, the user needs to rotate the lock lever 63 toward the release position until the connecting piece 65 comes out of the opening 29 of the peripheral wall 28 after opening the jam handling cover 40, and a reliable operation procedure without erroneous operation. Is secured.
[0031]
On the other hand, when replacing the process unit 6 pulled out from the apparatus frame 27 and mounting the replaced process unit 6 on the apparatus frame 27, first, the process unit 6 is pushed into the apparatus frame 27 and then the lock lever 63 is pressed. Needs to be rotated from the release position to the lock position. As a result, the process unit 6 is positioned at a predetermined position of the apparatus frame 27. Further, when the lock lever 63 is set to the lock position, the stopper lock member 53 of the stopper mechanism 50 is lifted by the connecting piece 65 at the tip of the lock lever 63, whereby the jam processing cover 40 can be closed. When the process unit 6 is only pushed into the apparatus frame 27 and the lock lever 63 is still set to the release position, the stopper lock member 53 is moved from the second position of the stopper pin 52 (solid line position in FIG. 6) to the first position. Since the movement to the position (two-dot chain line position) is locked, the stopper pin 52 is in a state protruding from the left end of the device frame 27, and the jam processing cover 40 and the stopper pin 52 interfere with each other. The jam handling cover 40 cannot be closed.
[0032]
That is, in this printer, unless the lock lever 63 of the process unit 6 is set to the lock position, the jam processing cover 40 cannot be closed, and the replacement operation of the process unit 6 cannot be completed. Accordingly, unless the second intermediate transfer drum 3 is positioned at a predetermined position in the apparatus frame 27, the final transfer roll 4 is not pressed against the second intermediate transfer drum 3, and the user can replace the process unit 6 correctly. It is possible to avoid a trouble that the final transfer roll 4 and the second intermediate transfer drum 3 are in pressure contact with each other in a state where it is not performed.
[0033]
Further, since the connecting piece 65 of the lock lever 63 engages with the stopper mechanism 50 through the opening 29 formed in the peripheral wall 28 of the apparatus frame 27, before the process unit 6 is completely pushed into the apparatus frame 27. When the lock lever 63 is rotated at this stage, the connecting piece 65 interferes with the peripheral wall 28. Therefore, in order to rotate the lock lever 63 to the lock position, it is necessary to push the process unit 6 completely to the back of the apparatus frame 27, and in this respect as well, it is possible to prevent a user's erroneous operation.
[0034]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the image forming unit can be attached to and detached from the apparatus frame on the condition that the transfer member is set at the retracted position separated from the image carrier. Therefore, it is possible to completely prevent a user's erroneous operation when attaching / detaching the image forming unit to / from the apparatus frame, and the user can attach / detach the image forming unit with a simple operation.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of a color laser beam printer to which the present invention is applied.
FIG. 2 is a perspective view showing a state in which a process unit is extracted from an apparatus frame.
FIG. 3 is a schematic diagram illustrating a state where a jam processing cover of the printer illustrated in FIG. 1 is opened.
FIG. 4 is a perspective view showing a state in which a process unit is mounted on the apparatus frame.
FIG. 5 is a perspective view showing a stopper mechanism.
FIG. 6 is a diagram illustrating an operational relationship between a lock lever and a stopper mechanism of a process unit.
[Explanation of symbols]
1Y, 1M, 1K, 1C ... photosensitive drum, 2 ... first intermediate transfer drum, 3 ... second intermediate transfer drum (image carrier), 4 ... final transfer roll (transfer member), 6 ... process unit (image formation) Unit), 27 ... device frame, 40 ... jam handling cover, 52 ... stopper pin (stopper member), 53 ... stopper lock member, 63 ... lock lever

Claims (7)

In an image forming apparatus configured to insert a recording sheet between an image carrier and a transfer member in contact with each other, and to transfer a toner image formed on the image carrier to the recording sheet,
The transfer member is provided so as to be detachable from the image carrier, while the image carrier is mounted on an image forming unit that is detachable from the apparatus frame.
The image forming unit is configured to be allowed to be attached to and detached from the apparatus frame on the condition that the transfer member is set at a retracted position separated from the image carrier .
The image forming unit is provided with a lock lever for positioning and fixing the unit to the operating position,
The apparatus frame is provided with a jam processing cover for jamming the recording sheet, and is linked to the closing of the jam processing cover, and is set to the first position when closed and to the second position when opened. Provided with a stopper member,
When the jamming cover is moved from the open position to the closed position when the lock lever is not in the fixed position for fixing the image forming unit, the stopper member is restricted from moving from the second position to the first position, and An image forming apparatus, wherein the jam treatment cover and the stopper member interfere with each other to prevent the cover from being closed .   2. The image forming apparatus according to claim 1, wherein the lock lever can be operated from the lock position to the release position on condition that the transfer member is set at the retracted position.   3. The image forming apparatus according to claim 2, wherein the transfer member can be set to a pressure contact position with the image carrier on condition that the lock lever is set to the lock position. The transfer member is mounted on a jam processing cover that can be freely opened and closed with respect to the apparatus frame, and is configured to be set to the retracted position or the contact position in accordance with the opening and closing of the jam processing cover.
4. The image forming apparatus according to claim 3, wherein the stopper member set at the first position is configured to lock the lock lever of the image forming unit at the lock position. The device frame is provided with a stopper lock member for locking the movement of the stopper member from the second position to the first position,
5. The image forming apparatus according to claim 4, wherein the stopper lock member is retracted from the locking position of the stopper member in conjunction with a setting change from the unlocked position of the lock lever of the image forming unit to the locked position.   The apparatus frame is covered with a part of the lock lever with respect to a direction in which the image forming unit is attached to or detached from the apparatus frame in a state where the lock lever of the image forming unit is set to a lock position. The image forming apparatus according to any one of 2 to 5.   7. The stopper member and the stopper lock member are surrounded by a peripheral wall, and the lock lever is engaged with the stopper lock member through an opening formed in the peripheral wall. Image forming apparatus.

Images