JP2005055817A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform appropriate processing based upon the result of the detection by a detecting means, in an image forming apparatus having the detection means which is on when paper is present in a specific part of a paper conveyance path and when a cover covering the paper conveyance path is open. <P>SOLUTION: A laser printer (image forming apparatus) has the sensor which is on when paper is present in the specific part of the paper conveyance path and when the fixing cover covering the paper conveyance path is open. When the sensor is on at a point in time that the power source of the printer is turned on (S110:Y), display informing that a jam has occurred is shown (S120). In addition, when a printing operation does not take place, display informing that the fixing cover is open is shown (S150, S230) if the sensor is turned on during the stop of a conveying motor (S140:Y, S220:Y), whereas display informing that a jam has occurred is shown (S190) if the sensor is turned on during the drive of the conveying motor (S180:Y). When the printing operation takes place, on the other hand, whether a jam has occurred or not is determined based on the result of detection by the sensor (S260). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including a detecting unit that detects whether a sheet is present at a specific position in a sheet conveyance path and when a cover that covers the sheet conveyance path is open.

Some conventional image forming apparatuses include a detection unit that detects whether a sheet is present at a specific position in the sheet conveyance path and when a cover that covers the sheet conveyance path is open.
For example, Patent Document 1 discloses an image forming apparatus having the following configuration.

That is, the image forming apparatus includes a fixing cover that covers a fixing unit that thermally fixes a toner image transferred onto a sheet, and a fixing portion is fixed to a central portion of a rotating shaft that is rotatably supported by the fixing cover. A paper discharge actuator that rotates when the paper passing through the section contacts is provided, and a light shielding member that rotates together with the paper discharge actuator is provided at the end of the rotating shaft. When the sheet is not present in the fixing unit, the light interrupting member blocks the light interrupting path of the photo interrupter, thereby turning off the photo interrupter detection result. On the other hand, when the paper passes through the fixing unit, the paper discharge actuator is pushed up by the paper, and the light shielding member is moved accordingly to open the light incident path of the photo interrupter, so that the photo interrupter detection result is turned on. become. In addition, when the fixing cover is opened, the rotating shaft supported by the fixing cover moves, and the light shielding member also moves in accordance therewith to open the light interrupting path of the photo interrupter. Turn on.
Japanese Patent Laid-Open No. 6-171794 (page 3, FIGS. 1 to 3)

  In the image forming apparatus having the above-described configuration, when the detection result of the photo interrupter is on, the sheet is present in the fixing unit and the fixing cover is opened. It can be judged that there is. However, there has been no technique for appropriately determining which of these states.

  The present invention has been made in view of these problems, and includes a detection unit that is in a detection state when a sheet is present at a specific position of the sheet conveyance path and when a cover covering the sheet conveyance path is open. An object of the image forming apparatus is to perform an appropriate process based on a detection result of a detection unit.

  An image forming apparatus according to claim 1, wherein the image forming apparatus is configured to perform a printing operation of printing an image on a sheet while performing a conveying operation of conveying the sheet along a sheet conveying path. Detecting means for detecting whether a sheet is present at a specific position in the sheet conveyance path and when a cover covering the sheet conveyance path is open. Further, the apparatus includes a determination unit that determines whether or not a jam has occurred in the paper conveyance path and whether the cover is open or closed based on the detection result of the detection unit. The determination means determines whether or not a jam has occurred in the paper conveyance path based on the detection result of the detection means in a state where the printing operation (the operation of printing an image on the paper while performing the conveyance operation) is performed. In a state where the printing operation is not performed, it is determined according to the operation state of the image forming apparatus whether the detection state of the detection means indicates the occurrence of a jam in the paper conveyance path or the cover open state. .

  Therefore, according to the image forming apparatus, it is possible to perform appropriate processing based on the detection result of the detection unit. In other words, the cause of the detection means being in the detection state when the printing operation is not being performed may be a case where a jam occurs in the paper conveyance path or a case where the cover is opened. It is possible to make an appropriate determination by determining whether there is an image according to the operating state of the image forming apparatus.

Here, examples of the operation state of the image forming apparatus referred to by the determination unit include the state of the conveyance operation.
That is, in the image forming apparatus according to the second aspect, in the apparatus according to the first aspect, when the determination unit is in a state where the printing operation is not performed, the detection unit is in the detection state while the conveyance operation is performed. In this case, it is determined that the detected state indicates the occurrence of a jam in the paper conveyance path.

  Even if the printing operation is not performed, if the paper remains for some reason in the paper transport path, it is possible that the paper is transported by performing the transport operation. The presence of the sheet is detected by the detecting means when the sheet passes through a specific position on the conveyance path. For this reason, when the detection unit is in the detection state while the transport operation is being performed, it is highly likely that the detection state indicates the occurrence of a jam in the paper transport path. Therefore, according to the present image forming apparatus, it is possible to appropriately determine the content detected by the detection means.

  According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the determination unit detects the state in which the conveying operation is not performed when the printing operation is not performed. It is characterized by determining that the detected state indicates the open state of the cover when the state is reached.

  When the transport operation is not performed, it is unlikely that the paper will pass through a specific position on the paper transport path, so if the detection means enters the detection state when the transport operation is not performed, The detection state is likely to indicate the open state of the cover. Therefore, according to the image forming apparatus, it is possible to more appropriately determine the content detected by the detection unit.

  By the way, when the detection unit is in a detection state when the power of the image forming apparatus is turned on, there is a sheet at a specific position (when a jam occurs in the sheet conveyance path) and Any of the cases where the cover is in the open state is considered.

  Therefore, according to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the determination means is in a detection state when the power of the image forming apparatus is turned on. If it is, it is determined that the detected state indicates the occurrence of a jam in the paper transport path.

  According to the image forming apparatus, it is possible to prompt the user to take appropriate measures. In other words, when a jam occurs in the paper transport path, the user can be encouraged to take appropriate measures, and even when the cover is open, the user can remove jams in the paper transport path. This is because by prompting confirmation of occurrence, it is possible to indirectly confirm the state of the cover.

On the other hand, whether or not a jam has occurred in the paper conveyance path in a state in which the printing operation is being performed can be determined, for example, as in claim 5.
That is, an image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein when the determination unit performs the printing operation, the detection result of the detection unit is a sheet of paper by the printing operation. It is characterized in that it is determined that a jam has occurred when the detection result is different from the detection result that should be obtained when the sheet is normally conveyed along the conveyance path.

  While the printing operation is being performed, the presence of the paper is detected by the detection means when the paper passes through a specific position on the paper conveyance path. However, if a jam occurs, the presence of the paper may not be detected. Conversely, a detection result such as the presence of the paper being detected for a long time is obtained. For this reason, according to the image forming apparatus, the detection result by the detection unit in a state where the printing operation is performed is the detection result by the detection unit that should be obtained when the paper is normally conveyed by the printing operation. By comparing, occurrence of jam can be accurately determined.

  Next, an image forming apparatus according to a sixth aspect includes a conveying unit that performs a conveying operation for conveying the sheet along the sheet conveying path, and a case where the sheet exists at a specific position on the sheet conveying path and the sheet. A detection unit that is in a detection state when the cover that covers the conveyance path is open, and a processing unit that performs specific processing based on a detection result by the detection unit are provided. In this apparatus, the processing means performs the specific processing by assuming that the detection state of the detection means indicates the presence of the sheet at the specific position when the transport operation is performed, and performs the transport operation. If not, it is assumed that the detection state of the detection means indicates the open state of the cover, and specific processing is performed.

  When the paper is transported by the transport operation of the transport means, its presence is detected when the paper passes through a specific position on the paper transport path, so the detection state of the detection means when the transport operation is being performed Is likely to indicate the presence of a sheet at a specific position in the sheet conveyance path. On the other hand, in the state where the transport operation by the transport means is not performed, it is unlikely that the paper will pass a specific position on the paper transport path, so the detection state of the detection means when the transport operation is not performed is covered. There is a high possibility that this indicates an open state. Therefore, according to the image forming apparatus, it is possible to perform appropriate processing based on the detection result of the detection unit.

  By the way, when the detection unit is in a detection state when the power of the image forming apparatus is turned on, there is a sheet at a specific position (when a jam occurs in the sheet conveyance path) and Any of the cases where the cover is in the open state is considered.

  Therefore, in the image forming apparatus according to claim 7, in the apparatus according to claim 6, when the processing unit is in a detection state when the power of the image forming apparatus is turned on, It is characterized in that a specific process is performed assuming that the detection state indicates the presence of a sheet at a specific position.

  According to the image forming apparatus, it is possible to prompt the user to take appropriate measures. In other words, when a sheet is present at a specific position, it is possible to prompt the user to take an appropriate action, and even when the cover is open, the user is notified of the presence of the sheet at the specific position. This is because the confirmation of the cover state or the like can be performed indirectly by prompting confirmation.

  The image forming apparatus according to claim 8 is the apparatus according to claim 6 or 7, wherein the processing unit prints an image on the sheet while conveying the sheet supplied to the sheet conveying path by the conveying operation of the conveying unit. In a state in which the printing operation to be performed is not performed, when the detection unit is in a detection state in a state in which the transport operation is performed, the occurrence of a jam is notified as a specific process.

  In a state where the printing operation is not performed, it is conceivable that the sheet passes through a specific position on the sheet conveyance path by the conveyance operation when the sheet remains in the sheet conveyance path. Therefore, according to the present image forming apparatus, it is possible to prompt the user to take an appropriate measure by notifying the occurrence of a jam.

  The image forming apparatus according to claim 9 is the apparatus according to any one of claims 6 to 8, wherein the processing unit conveys the sheet supplied to the sheet conveyance path by the conveyance operation of the conveyance unit. In a state where a printing operation for printing an image is being performed, the detection result by the detection unit is different from the detection result by the detection unit that should be obtained when the paper is normally conveyed along the paper conveyance path by the printing operation. In some cases, the notification of the occurrence of a jam is performed as a specific process.

  While the printing operation is being performed, the presence of the paper is detected by the detection means when the paper passes through a specific position on the paper conveyance path. However, if a jam occurs, the presence of the paper may not be detected. Conversely, a detection result such as the presence of the paper being detected for a long time is obtained. For this reason, according to the image forming apparatus, the detection result by the detection unit in a state where the printing operation is performed is the detection result by the detection unit that should be obtained when the paper is normally conveyed by the printing operation. By comparing, it is possible to accurately determine the occurrence of a jam and prompt the user to take appropriate measures.

  Next, an image forming apparatus according to a tenth aspect is the apparatus according to any one of the first to ninth aspects, wherein the sheet transported along the sheet transport path is passed between the two rotating members in pressure contact. A fixing device that fixes the image transferred onto the sheet to the sheet, and a contact pressure adjusting lever that adjusts the contact pressure between the two rotating members. In this apparatus, the cover covers the sheet conveyance path formed between the two rotating members, and the two contact pressure adjusting levers are moved along with the movement of the cover from the closed position to the open position. It moves to the side where the contact pressure between rotating members becomes low.

  According to this image forming apparatus, since the user moves the cover from the closed position to the open position (opens the cover), the contact pressure between the two rotating members of the fixing device is lowered. It is possible to easily perform processing when a jam occurs.

  Next, an image forming apparatus according to an eleventh aspect is the apparatus according to any one of the first to ninth aspects, wherein the sheet conveyed along the sheet conveyance path is passed between the two rotating members in pressure contact. The fixing device for fixing the image transferred on the sheet to the sheet, the contact pressure adjusting lever for adjusting the contact pressure between the two rotating members, and the cover on the exterior member of the image forming apparatus. And an opening / closing member that opens and closes an opening formed at a position. And in this apparatus, a cover covers the paper conveyance path formed between two rotation members. Further, in this apparatus, the opening / closing member moves the cover to the closed position side as the opening / closing member moves from the open position to the closed position, and the contact pressure adjusting lever is set to have a high contact pressure between the two rotating members. Move to the side.

  In this image forming apparatus, when the user moves the opening / closing member from the open position to the closed position (closes the opening / closing member), the cover is moved to the closed position side and the contact pressure between the two rotating members increases. . Therefore, according to this image forming apparatus, the opening / closing member is closed with the cover open, or the opening / closing member is closed while the contact pressure adjusting lever is on the side for reducing the contact pressure between the two rotating members. Can be prevented.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
In the present embodiment, a laser printer will be described as an example of the image forming apparatus of the present invention.

FIG. 1 is a perspective view illustrating an appearance of a laser printer 1 according to the present embodiment.
As shown in the figure, the laser printer 1 has a box-shaped main body case (corresponding to the exterior member of the present invention) 2, and an operation panel 3 is disposed on the upper surface of the main body case 2. The operation panel 3 is provided with a liquid crystal display 3a as a display unit so that the operating state of the laser printer 1 is displayed. In addition, the operation panel 3 is provided with operation switches 3b for performing input operations such as printing start and printing stop, and various operations are performed by performing input operations from these operation switches 3b. It has become.

  A paper feed cassette 4 is disposed below the main body case 2. The paper feed cassette 4 can store a plurality of sheets (recording sheets) and is detachably attached to the main body case 2.

  Further, a cover release button 8 is disposed on the upper surface of the main body case 2, and the engagement state between the main body case 2 and the front cover 7 is released when the cover release button 8 is pressed. .

Next, the internal configuration of the laser printer 1 will be described.
FIG. 2 is a cross-sectional view of the laser printer 1.
As shown in the figure, in the present laser printer 1, a paper feed cassette 4 is disposed below the main body case 2, and a support plate 11 urged upward by a spring (not shown) is provided therein. ing.

Above the support plate 11, a supply roller 13 is provided for separating sheets stacked on the support plate 11 one by one and supplying them to the image forming unit 5 described later.
Then, on the sheet conveyance path from the supply roller 13 to the image forming unit 5, conveyance rollers 15 and 17, and a registration roller 19 that locks the leading edge of the sheet by appropriately stopping and correcting skew of the sheet, Are sequentially arranged.

  The front cover 7 includes a multipurpose tray 23. A multi-purpose side paper feed roller 24 and a multi-purpose side paper feed pad for feeding paper stacked on the multi-purpose tray 23 are provided on the paper transport path from the multi-purpose tray 23 to the image forming unit 5. The multi-purpose sheet feeding pad 24a is pressed toward the multi-purpose sheet feeding roller 24 by a spring (not shown) disposed opposite to each other and disposed on the back side of the multi-purpose sheet feeding pad 24a. Yes. The sheets stacked on the multi-purpose tray 23 are fed one by one after being sandwiched between the multi-purpose side feed roller 24 and the multi-purpose side feed pad 24a by the rotation of the multi-purpose side feed roller 24. The

The image forming unit 5 includes a process cartridge 25 in which a photosensitive drum 27 and a developing roller 28 are incorporated, and a transfer roller 29 disposed to face the photosensitive drum 27.
On the downstream side of the image forming unit 5 (the right side in FIG. 2), a fixing device 33 including a heating roller 35 and a pressure roller 37 which are two rotary members mainly in pressure contact with each other via a conveyance belt 31 is provided. It has been.

  Further, on the downstream side of the fixing device 33, three pairs of paper discharge rollers 39, 40, and 41 are disposed along the paper conveyance path, and the main body case 2 is discharged from the paper discharge roller 41 on the most downstream side. A paper discharge tray 6 for receiving the paper to be printed is provided. Each of the paper discharge rollers 39, 40, and 41 includes a drive roller that rotates by receiving a drive from a later-described transport motor 72 (FIG. 9), and a driven roller that rotates by receiving the rotational force of the drive roller. ing.

  Further, a rear tray 42 for opening and closing an opening 2a formed at a position facing the fixing device 33 in the main body case 2 is provided on the back surface of the laser printer 1 (right side in FIG. 2). When the rear tray 42 is opened, the paper from the fixing device 33 is discharged to the rear tray 42 by the paper discharge roller 39.

  On the other hand, a scanner unit 44 that scans and exposes the photosensitive drum 27 with laser light L is disposed at a position between the paper discharge tray 6 and the process cartridge 25. The scanner unit 44 includes various optical elements such as a polygon mirror 45 that is rotated by a motor (not shown) for the purpose of scanning laser light emitted from a laser diode (not shown). Has been placed.

  The process cartridge 25 is attached to and detached from the upper part of the main body case 2 in the directions of arrows A and B with the front cover 7 rotated and moved downward. The process cartridge 25 is rotatably provided with a photosensitive drum 27 having a photosensitive layer on its surface, and further includes a charging roller (not shown) for uniformly charging the surface of the photosensitive drum 27, and the charged photosensitive drum 27. And a developing roller 28 for supplying toner to the surface.

  An electrostatic latent image is formed on the surface of the photosensitive drum 27 charged by the charging roller by the laser light L incident from the scanner unit 44. Subsequently, the developing roller 28 supplies toner as a developer to the surface of the photosensitive drum 27, whereby the electrostatic latent image is developed on the photosensitive drum 27, and a toner image (visible image) is formed.

Here, a printing operation performed to print an image on a sheet in the laser printer 1 will be described.
The paper taken out from the paper feed cassette 4 by the supply roller 13 is sent to the registration roller 19 by the rotation operation of the transport rollers 15 and 17, where the skew of the paper is corrected.

  Thereafter, when the sheet is sent to the image forming unit 5, the toner (attached to the photosensitive drum 27) is transferred when passing between the photosensitive drum 27 and the transfer roller 29, so that an image (toner image) is formed on the sheet. It is formed.

  The sheet having the toner image transferred thereon is conveyed to the fixing device 33 by the conveying belt 31, and is heated by the heating roller 35 when passing between the heating roller 35 and the pressure roller 37 in the fixing device 33. As a result, the image transferred onto the paper is fixed on the paper.

  Thereafter, the paper on which the image is printed is discharged to a paper discharge tray 6 provided on the upper surface of the main body case 2 by the rotation operation (conveyance operation) of the three pairs of paper discharge rollers 39 to 41. In the state where the rear tray 42 is opened, the sheet on which the image is fixed is discharged to the rear tray 42 by the rotation operation of the discharge roller 39.

Next, the configuration of the fixing device 33 will be described with reference to FIGS.
3 to 8 are sectional views of the fixing device 33.
As shown in FIG. 3A, the fixing device 33 includes the heating roller 35 and the pressure roller 37 described above, a fixing cover (corresponding to a cover of the present invention) 50, and a fixing frame 33a that supports them. The lower end of the fixing cover 50 is pivotally supported by the fixing frame 33a, and is configured to be movable between an open position shown in FIG. 3A and an open position shown in FIG. 3B. Has been.

  The fixing cover 50 is used in the closed position shown in FIG. 3A in a normal state (for example, during a printing operation). In this state, even when the rear tray 42 is opened, the sheet conveyance path formed between the heating roller 35 and the pressure roller 37 is covered with the fixing cover 50, and the user opens the sheet. Even if a hand is inserted from the portion 2a, the heating roller 35 and the pressure roller 37 cannot be touched.

  However, the user can open the fixing cover 50 in the direction of arrow E as shown in FIG. 3B when the rear tray 42 is opened. As a result, the sheet conveyance path formed between the heating roller 35 and the pressure roller 37 can be visually recognized through the opening 2a, and the jam processing in the fixing device 33 can be performed from the back surface of the laser printer 1. it can.

  Here, among the discharge rollers 39 (FIG. 2) described above, the driving roller 39a is supported by the fixing cover 50, and the driven roller 39b is supported by the fixing frame 33a. Therefore, in the state where the fixing cover 50 is closed (FIG. 3A), the driving roller 39a and the driven roller 39b are arranged at positions where they are in contact with each other, but the fixing cover 50 is opened (FIG. 3). In (b)), the driving roller 39a and the driven roller 39b are disposed at positions separated from each other.

  By the way, the fixing cover 50 is provided with a swinging member 52 that is used to detect the open state of the fixing cover 50 and the presence of the paper transported through the paper transport path. The swing member 52 is supported by the fixing cover 50 so as to be swingable about the rotation shaft 53.

  The fixing frame 33a has a light emitting portion and a light receiving portion so that the lower end portion 52a of the swinging member 52 is sandwiched from both sides in the axial direction of the rotating shaft 53 in a state where the fixing cover 50 is closed (FIG. 3A). And a sensor (photo interrupter) 54 is provided.

For this reason, as shown in FIG. 3A, when the fixing cover 50 is closed, the lower end portion 52a of the swinging member 52 is in a position for blocking between the light emitting portion and the light receiving portion of the sensor 54. .
On the other hand, when the fixing cover 50 is opened, as the fixing cover 50 moves from the closed position to the open position (moving in the direction of arrow E), the position of the rotary shaft 53 that supports the swing member 52 also moves. As shown in FIG. 3B, the portion of the swing member 52 below the rotation shaft 53 abuts on a rib 42 a that constitutes a part of the rear tray 42 and its movement is restricted. Thus, when the fixing cover 50 is opened, the swinging member 52 is tilted in the same direction as the fixing cover 50, and the lower end 52a of the swinging member 52 is located between the light emitting unit and the light receiving unit of the sensor 54. It will be a position that does not block the gap.

  Further, in a state in which the fixing cover 50 is closed (FIG. 3A), the sheet conveyed through between the heating roller 35 and the pressure roller 37 passes between the driving roller 39a and the driven roller 39b. When passing, the upper end portion 52b of the swinging member 52 is pushed by the sheet, so that the swinging member 52 is tilted in the direction of arrow C (the direction rotating clockwise in the drawing) as shown in FIG. It becomes the state. As a result, as in the case where the fixing cover 50 is opened, the lower end portion 52a of the swinging member 52 is positioned so as not to block between the light emitting portion and the light receiving portion of the sensor 54.

  That is, normally, the detection result of the sensor 54 is turned off by the lower end 52a of the swinging member 52 blocking the light emitting portion and the light receiving portion of the sensor 54, but the fixing cover 50 is opened. If the sheet is present at a position between the driving roller 39a and the driven roller 39b, the lower end 52a of the swing member 52 does not block between the light emitting portion and the light receiving portion of the sensor 54. As a result, the detection result of the sensor 54 is turned on. Thus, the single sensor 54 detects the open state of the fixing cover 50 and the presence of paper at the position where the paper discharge roller 39 is provided.

On the other hand, as shown in FIG. 5, the fixing device 33 includes an urging support member 56, a spring 57, and a nip release lever 58.
The urging support member 56 is a member that rotatably supports the pressure roller 37, and the urging support member 56 itself is supported by a rotation shaft 56a fixed to the fixing frame 33a so as to be rotatable. The spring 57 has a lower end fixed to the fixing frame 33a and an upper end in contact with the lower surface of the plate portion 56b formed on the opposite side of the urging support member 56 from the rotation shaft 56a. It is energizing upward. By this urging force, the urging support member 56 is urged in the direction of rotating counterclockwise in FIG. 5 around the rotation shaft 56 a, and the pressure roller 37 is pressed against the heating roller 35. The urging support members 56 are respectively provided at both end positions along the axial direction of the pressure roller 37.

  The nip release lever 58 is supported by the fixing frame 33a so as to be rotatable about the rotation shaft 58a. The nip release lever 58 has its handle 58b pulled down by the user in the clockwise direction shown in FIG. 5, so that the protrusion 58c formed at the other end of the plate portion 56b of the urging support member. It abuts on the upper surface and acts to push down the plate portion 56b against the urging force of the spring 57. When the nip release lever 58 is pulled down to the position shown in FIG. 5B (hereinafter referred to as “release position”), the upward urging force by the spring 57 is suppressed by the rotating shaft 58a, and the user can Even if the hand is released from the nip release lever 58, the nip release lever 58 is maintained in this release position.

  When the plate portion 56b is pushed downward in this manner, the urging support member 56 moves in the arrow D direction (the direction rotating clockwise in the drawing) around the rotation shaft 56a. As a result, the contact pressure between the heating roller 35 and the pressure roller 37 is reduced (the nip width is reduced). For this reason, for example, when printing on an envelope, printing can be performed in a state where the nip release lever 58 is lowered to the release position and the contact pressure is reduced. Further, in this case, the rear tray 42 is opened, and the envelope is discharged from the discharge roller 39 to the rear tray 42, so that the paper is conveyed through the curved sheet conveyance path by the discharge rollers 39 to 41. This can prevent the envelope from being wrinkled. The nip release lever 58 is also provided at both end positions along the axial direction of the pressure roller 37, similarly to the urging support member 56. That is, in order to reduce the contact pressure between the heating roller 35 and the pressure roller 37, the user needs to perform an operation of pulling down the two nip release levers 58 provided in the fixing device 33.

  Incidentally, the nip release lever 58 is pushed down to the release position also when the fixing cover 50 is opened. That is, when the user performs an operation to open the fixing cover 50 in a state where the nip release lever 58 is in the position shown in FIG. 5A (hereinafter referred to as “biasing position”), FIG. ), As the fixing cover 50 moves from the closed position to the open position (moving in the direction of arrow E), the fixing cover 50 comes into contact with the handle 58b of the nip release lever 58, and the nip release lever 58 Moves together with the fixing cover 50. For this reason, when the user handles a jam occurring in the fixing device 33, the user only has to open the fixing cover 50 by putting his hand through the opening 2a. The urging position is moved to the release position.

  On the other hand, in the laser printer 1, when the user performs an operation to close the rear tray 42 with the fixing cover 50 opened, the fixing cover 50 is closed along with the movement of the rear tray 42. The nip release lever 58 is moved from the release position to the urging position.

Here, the operation in the process of moving the rear tray 42 from the open position to the closed position will be described.
First, when the rear tray 42 is moved from the fully open position to the position shown in FIG. 6, the contact member 42 b that constitutes a part of the rear tray 42 and the fixing cover 50 come into contact with each other at a position indicated by an arrow F. For this reason, when the rear tray 42 further moves to the closed position side (arrow G direction), the fixing cover 50 also moves to the closed position side (arrow G direction) accordingly. Here, the other end of the spring 60 whose one end is fixed to the fixing frame 33 a is fixed to the lower end portion of the fixing cover 50, and when the fixing cover 50 is closed to a position, thereafter, the force of the spring 60 is used. The lower end is pulled and automatically moved to the closed position. For this reason, when the rear tray 42 further moves from the position shown in FIG. 6 to the closed position side to some extent, the fixing cover 50 is automatically moved to the closed position by the force of the spring 60.

  Thereafter, when the rear tray 42 moves to the position shown in FIG. 7, the contact member 42 c constituting a part of the rear tray and the nip release lever 58 come into contact at a position indicated by an arrow H. For this reason, when the rear tray 42 further moves to the closed position side (arrow G direction), the nip release lever 58 also moves to the biasing position side (arrow G direction). Here, when the nip release lever 58 moves to a certain position, the nip release lever 58 is automatically moved to the urging position by the upward urging force of the spring 57 (FIG. 5). Therefore, when the rear tray 42 further moves from the position shown in FIG. 7 to the closed position side to some extent, the nip release lever 58 automatically moves to the biased position by the force of the spring 57.

Therefore, when the rear tray 42 is moved to the fully closed position, as shown in FIG. 8, the fixing cover 50 is closed, and the nip release lever 58 is in the urging position.
Next, the electrical configuration of the laser printer 1 will be described.

FIG. 9 is a block diagram showing an electrical configuration of the laser printer 1. Only the configuration particularly related to the main processing (FIG. 10) described later will be described here.
As shown in the figure, the laser printer 1 includes a known CPU, ROM and RAM, the sensor 54, the liquid crystal display 3a and the operation switch 3b, the heater 70 built in the heating roller 35, the driving roller 39a, and the like. And a transport motor 72 that performs a rotation operation (transport operation).

  Next, main processing performed by the CPU will be described with reference to the flowchart of FIG. This main process is started when the laser printer 1 is turned on.

  When this main process is started, it is first determined in S110 whether or not the sensor 54 is on. That is, the detection result of the sensor 54 at the time when the power of the laser printer 1 is turned on is determined.

  If it is determined in S110 that the sensor 54 is on, the process proceeds to S120, and a jam occurrence display process for displaying on the liquid crystal display 3a that a jam has occurred is performed. As described above, when the sensor 54 is turned on (in a detection state) at the time when the power of the laser printer 1 is turned on, the on state of the sensor 54 indicates the presence of paper in the paper discharge roller 39. It is determined that a jam has occurred. That is, as the cause of the sensor 54 being turned on when the power is turned on, any of the possibility of jamming and the case where the fixing cover 50 is opened can be considered, but jamming has occurred. This is because the user can be made aware of the open state of the fixing cover 50 even if the fixing cover 50 is open. The jam occurrence display process is performed when it is detected that the jam process is completed (for example, when the sensor 54 is turned off, or in addition, when an input operation indicating the completion of the jam process is performed from the operation switch 3b). Etc.) and the process proceeds to the next process (S130).

On the other hand, if it is determined in S110 that the sensor 54 is not turned on, the process proceeds to S130 as it is.
In S <b> 130, the heater 70 built in the heating roller 35 is turned on as a warm-up operation for heating the heating roller 35.

Subsequently, in S140, it is determined whether or not the sensor 54 is on.
If it is determined in S140 that the sensor 54 is on, the process proceeds to S150, and a cover open state display process for displaying on the liquid crystal display 3a that the fixing cover 50 is open is performed. As described above, when the sensor 54 is turned on before driving the conveyance motor 72 in S170 described later, the on state of the sensor 54 is regarded as indicating the open state of the fixing cover 50. This is because it is unlikely that the passage of the paper has been detected by the sensor 54 when the transport motor 72 is stopped, and it is highly likely that the fixing cover 50 is open. During the cover open state display process, the heater 70 is turned off. In addition, the cover open state display process is performed when it is detected that the fixing cover 50 is closed (for example, when the sensor 54 is turned off, or in addition, an input operation indicating completion of the closing operation of the fixing cover 50 is performed). And the process proceeds to the next process (S160).

On the other hand, if it is determined in S140 that the sensor 54 is not turned on, the process proceeds to S160 as it is.
In S160, it is determined whether or not the temperature of the heating roller 35 has increased to a predetermined temperature.

  If it is determined in S160 that the temperature has not risen to the predetermined temperature, the process returns to S140, and if it is determined that the temperature has risen to the predetermined temperature, the process proceeds to S170. That is, when the heating roller 35 rises to a predetermined temperature, the process proceeds to S170.

In S170, the drive of the conveyance motor 72 is started as initialization operation. As a result, the drive roller 39a and the like rotate.
Subsequently, in S180, it is determined whether or not the sensor 54 is on. That is, it is determined whether or not the sensor 54 is turned on while the transport motor 72 is being driven.

  If it is determined in S180 that the sensor 54 is on, the process proceeds to S190, and similarly to S120, a jam occurrence display process for displaying on the liquid crystal display 3a that a jam has occurred is performed. As described above, when the sensor 54 is turned on during the driving of the transport motor 72 as the initialization operation, it is assumed that the on state of the sensor indicates the presence of the paper in the paper discharge roller 39, and a jam occurs. It comes to judge that it is doing. This is because even when the printing operation is not performed, if the sheet remains for some reason in the sheet conveyance path, the sheet is conveyed by driving the conveyance motor 72 and the sensor 54 is turned on. This is because there is a high possibility that it indicates the presence of paper. During the jam occurrence display process, the heater 70 is turned off and the transport motor 72 is stopped. Further, the jam occurrence display process is terminated when it is detected that the jam process is completed, as in S120, and the process proceeds to the next process (S200).

On the other hand, if it is determined in S180 that the sensor 54 is off, the process proceeds to S200 as it is.
In S200, it is determined whether or not the driving time of the conveyance motor 72 after starting the driving of the conveyance motor 72 in S170 has reached a predetermined time (for example, 6 seconds) determined in advance.

  If it is determined in S200 that the predetermined time has not been reached, the process returns to S180, and if it is determined that the predetermined time has been reached, the process proceeds to S210. That is, when the driving time of the transport motor 72 reaches a predetermined time, the process proceeds to S210.

  In S210, the driving of the transport motor 72 is stopped. As a result, the initialization operation is completed, and a standby state is entered in which it waits until it receives a print start command as an image print request from a personal computer (not shown).

In S220, it is determined whether or not the sensor 54 is on. That is, it is determined whether or not the sensor 54 is turned on during the standby state.
If it is determined in S220 that the sensor 54 is on, the process proceeds to S230, and similarly to S150, a cover open state display process for displaying on the liquid crystal display 3a that the fixing cover 50 is open is performed. . As described above, when the sensor 54 is turned on during the standby state, the on state of the sensor 54 is regarded as indicating the open state of the fixing cover 50. As described above, it is unlikely that the passage of the sheet is detected by the sensor 54 when the conveyance motor 72 is stopped, and it is highly likely that the fixing cover 50 is open. It is. During the cover open state display process, the heater 70 is turned off. The cover open state display process is terminated when it is detected that the fixing cover 50 is closed, as in S150, and the process proceeds to the next process (S240).

On the other hand, if it is determined in S220 that the sensor 54 is not turned on, the process proceeds to S240 as it is.
In S240, it is determined whether or not a print start command is received from a personal computer (not shown).

If it is determined in S240 that the print start command has not been received, the process returns to S220. That is, it waits until it receives a print start command.
On the other hand, if it is determined in S240 that a print start command has been received, the process proceeds to S250, and a printing operation for printing an image on paper is started. In this printing operation, the transport motor 72 is driven to transport the paper.

  Subsequently, in S260, based on the detection result of the sensor 54, it is determined whether or not a jam has occurred. In other words, during the printing operation, the ON state of the sensor 54 is regarded as indicating the presence of the paper in the paper discharge roller 39. This is because if the sensor 54 is turned on during the printing operation, the possibility of detecting the passage of the sheet is considered to be extremely high.

Here, a specific method for determining whether or not a jam has occurred will be described.
When the sheet is normally conveyed by the printing operation, the sensor 54 is turned on when the leading end of the sheet passes the position of the upper end portion 52b of the swinging member 52, and then the trailing end of the sheet is the swinging member. When passing the position of the upper end portion 52b of the sensor 52, the sensor 54 is turned off. Therefore, an elapsed time after a sensor (not shown) that detects the passage of the paper in the vicinity of the registration roller 19 detects the passage of the leading edge of the paper is measured, and the detection result of the sensor 54 with respect to this elapsed time is detected by the printing operation. It is determined that a jam has occurred when the detection result is different from the detection result that should be detected by the sensor 54 when the sheet is normally conveyed along the conveyance path. For this reason, not only the case where the jam occurs and the sensor 54 does not turn on before the leading edge of the sheet passes the position of the upper end portion 52 b of the swinging member 52, but also the leading end of the sheet is the upper end portion 52 b of the swinging member 52. Even when the jam occurs and the sensor 54 continues to be turned on after the sheet passes the position and before the trailing edge of the sheet passes the position of the upper end portion 52b of the swing member 52, the jam can be detected.

  If it is determined in S260 that a jam has occurred, the process proceeds to S270, and a jam occurrence display process for displaying on the liquid crystal display 3a that a jam has occurred is performed as in S120 and S190. During the jam occurrence display process, the heater 70 is turned off and the printing operation is stopped. Further, the jam occurrence display process is terminated when it is detected that the jam process is completed, similarly to S120 and S190, and the process proceeds to the next process (S280).

On the other hand, if it is determined in S260 that a jam has not occurred, the process proceeds to S280 as it is.
In S280, it is determined whether the printing operation is completed.

If it is determined in S280 that the printing operation has not been completed, the process returns to S260.
On the other hand, if it is determined in S280 that the printing operation is completed, the process returns to S220 and enters a standby state.

As described above, in the laser printer 1, during the printing operation, it is determined whether or not a jam has occurred based on the detection result of the sensor 54.
On the other hand, during the non-printing operation, it is determined based on the state of the laser printer 1 when the sensor 54 is turned on whether the jam occurs or the fixing cover 50 is open. Specifically, if the sensor 54 is turned on when the laser printer 1 is turned on, it is determined that a jam has occurred. Further, when the sensor 54 is turned on while the power of the laser printer 1 is on, if the sensor 54 is turned on while the conveyance motor 72 is being driven, it is determined that a jam has occurred, and the conveyance motor 72 If the sensor 54 is turned on during the stop, it is determined that the fixing cover 50 has been opened.

  In the laser printer 1 of the above embodiment, the supply roller 13, the conveyance rollers 15 and 17, the registration roller 19, the image forming unit 5, the conveyance belt 31, the fixing device 33, and the paper discharge rollers 39 to 41 are included in the image of the present invention. The sensor 54 corresponds to the forming means, the detection means of the present invention, and the processing of S110, S120, S140, S150, S180, S190, S220, S230, S260, and S270 in the main processing (FIG. 10) is the main processing. This corresponds to the determination means of the invention. Further, the driving roller 39a corresponds to the conveying unit of the present invention, and the processes of S120, S150, S190, S230, S260, and S270 in the main process correspond to the processing unit of the present invention. The nip release lever 58 corresponds to the contact pressure adjusting lever of the present invention, and the rear tray 42 corresponds to the opening / closing member of the present invention.

  As described above, in the laser printer 1 of the present embodiment, during the printing operation, it is assumed that the ON state of the sensor 54 indicates the presence of the paper in the paper discharge roller 39, and the jam is based on the detection result of the sensor 54. It is determined whether or not the error occurred. Further, during the non-printing operation, if the sensor 54 is turned on while the transport motor 72 is being driven, it is considered that the on state of the sensor 54 indicates the presence of paper in the paper discharge roller 39, and a jam has occurred. If the sensor 54 is turned on while the transport motor 72 is stopped, the on state of the sensor 54 is regarded as indicating the open state of the fixing cover 50. Therefore, according to the laser printer 1, the operation of the laser printer 1 is adopted while adopting a low-cost configuration in which the common sensor 54 detects the open state of the fixing cover 50 and the presence of the paper in the paper discharge roller 39. It is possible to make an appropriate determination according to the state, and to prompt the user to take an appropriate treatment.

  In the laser printer 1, when the sensor 54 is turned on when the laser printer 1 is turned on, the fact that a jam has occurred is displayed on the liquid crystal display 3a. Therefore, according to the laser printer 1, the sensor 54 is turned on when the power is turned on regardless of whether a jam occurs or the fixing cover 50 is open. Treatment can be performed.

  Further, in this laser printer 1, it is considered that the ON state of the sensor 54 during the printing operation indicates the presence of the paper in the paper discharge roller 39, and the detection result of the sensor 54 is normally conveyed by the printing operation. In this case, a jam is detected by comparing with a detection result that should be detected by the sensor 54. For this reason, according to the laser printer 1, the common sensor 54 detects the open state of the fixing cover 50 and the presence of the paper in the paper discharge roller 39, and reliably jams occurring in various patterns. Can be detected.

  On the other hand, in the laser printer 1, the driven roller 39b is supported by the fixing frame 33a, but the driving roller 39a is supported by the fixing cover 50, and the fixing cover 50 is opened (FIG. 3B). The driving roller 39a and the driven roller 39b are disposed at positions separated from each other. For this reason, according to the present laser printer 1, it is possible to improve the jam handling performance when a jam occurs in the fixing device 33. That is, assuming that not only the driven roller 39b but also the driving roller 39a is supported by the fixing frame 33a, the position of the driving roller 39a does not change even when the fixing cover 50 is opened. When carrying out jam processing with a hand in hand, the drive roller 39a becomes in the way, making jam processing difficult. On the other hand, in the configuration in which the driving roller 39a moves together with the fixing cover 50 as in the case of the laser printer 1, it is possible to secure a wide working space for jamming and to improve visibility. .

  Further, the laser printer 1 is configured such that when the fixing cover 50 is opened, the nip release lever 58 is pushed down to the release position. Therefore, according to the laser printer 1, the user needs to perform a troublesome operation such as opening the fixing cover 50 after lowering the two nip release levers 58 when performing the jam processing in the fixing device 33. In addition, the two nip release levers 58 can be simultaneously pushed down by a simple operation by simply opening the fixing cover 50. Further, when the nip release lever 58 is pushed down, the contact pressure between the heating roller 35 and the pressure roller 37 is lowered, so that the sheet can be easily pulled out and jamming can be easily performed.

  Further, in the laser printer 1, the fixing cover 50 is closed by closing the rear tray 42, and the nip release lever 58 is in the urging position. Therefore, according to the laser printer 1, the user does not have to perform a troublesome operation such as closing the fixing cover 50, lifting the two nip release levers 58 to the urging position, and further closing the rear tray 42. The operability can be improved, and forgetting to close the fixing cover 50 and forgetting to return the nip release lever 58 can be prevented.

As mentioned above, although one Embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form.
For example, in the laser printer 1 of the above embodiment, the transport motor 72 is driven for a predetermined time as the initialization operation, but the present invention can also be applied to an apparatus that does not perform such initialization operation. As the main process in this case, for example, the contents of the main process (FIG. 10) of the above-described embodiment may be such that the processes from S170 to S210 are not performed.

  The present invention can be applied not only to a laser printer but also to a copying machine, a facsimile machine, and other image forming apparatuses.

It is a perspective view showing the external appearance of a laser printer. It is sectional drawing of a laser printer. FIG. 3 is a cross-sectional view of a fixing device for explaining an open / closed state of a fixing cover. It is sectional drawing of the fixing device for demonstrating a motion of a rocking | swiveling member. It is sectional drawing of the fixing device for demonstrating a motion of a nip release lever. FIG. 6 is a cross-sectional view of the fixing device for explaining a contact position between the rear tray and the fixing device. FIG. 4 is a cross-sectional view of a fixing device for explaining a contact position between a rear tray and a nip release lever. FIG. 6 is a cross-sectional view of the fixing device with the rear tray closed. It is a block diagram showing the electric constitution of a laser printer. It is a flowchart of a main process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser printer, 2 ... Main body case, 2a ... Opening part, 3 ... Operation panel, 3a ... Liquid crystal display, 3b ... Operation switch, 5 ... Image forming part, 6 ... Discharge tray, 13 ... Supply roller, 15, 17 DESCRIPTION OF SYMBOLS ... Conveyance roller, 19 ... Registration roller, 25 ... Process cartridge, 27 ... Photosensitive drum, 28 ... Development roller, 29 ... Transfer roller, 31 ... Conveyance belt, 33 ... Fixing device, 33a ... Fixing frame, 35 ... Heating roller, 37 ... pressure roller, 39, 40, 41 ... discharge roller, 39a ... drive roller, 39b ... driven roller, 42 ... rear tray, 50 ... fixing cover, 52 ... swing member, 54 ... sensor, 58 ... nip release lever, 74 ... Sensor

Claims (11)

An image forming means for performing a printing operation for printing an image on the paper while performing a transport operation for transporting the paper along the paper transport path;
Detection means that is in a detection state when a sheet is present at a specific position of the sheet conveyance path and when a cover covering the sheet conveyance path is open;
In an image forming apparatus comprising:
Based on a detection result by the detection means, comprising a determination means for determining whether or not a jam has occurred in the paper transport path and an open / closed state of the cover;
The determination unit determines whether or not a jam has occurred in the paper transport path based on a detection result of the detection unit in a state where the printing operation is performed, and in a state where the printing operation is not performed, Determining whether the detection state of the detection means indicates the occurrence of a jam in the paper transport path or the open state of the cover according to the operation state of the image forming apparatus;
An image forming apparatus. The image forming apparatus according to claim 1.
In the state where the printing operation is not performed, the determination unit is configured to detect a jam in the paper transport path when the detection unit is in a detection state while the transport operation is performed. To determine that
An image forming apparatus. The image forming apparatus according to claim 1, wherein:
In the state where the printing operation is not performed, the determination unit indicates that the detection state indicates an open state of the cover when the detection unit is in a detection state when the conveyance operation is not performed. Judging that
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The determination unit determines that the detection state indicates the occurrence of a jam in the sheet conveyance path when the detection unit is in a detection state when the image forming apparatus is turned on. about,
An image forming apparatus. 5. The image forming apparatus according to claim 1, wherein:
In the state in which the printing operation is performed, the determination unit is configured to detect the detection result obtained by the detection unit when the sheet is normally conveyed along the sheet conveyance path by the printing operation. If it is different from the detection result by the means, it is determined that a jam has occurred,
An image forming apparatus. A transport means for performing a transport operation for transporting the paper along the paper transport path;
Detection means that is in a detection state when a sheet is present at a specific position of the sheet conveyance path and when a cover covering the sheet conveyance path is open;
Processing means for performing specific processing based on a detection result by the detection means;
An image forming apparatus comprising:
In the state where the transport operation is being performed, the processing unit regards the detection state of the detection unit as indicating the presence of a sheet at the specific position, performs the specific process, and performs the transport operation. In the state that is not, the detection state of the detection means is regarded as indicating the open state of the cover, the specific processing is performed,
An image forming apparatus. The image forming apparatus according to claim 6.
If the detection unit is in a detection state at the time when the image forming apparatus is turned on, the processing unit regards the detection state as indicating the presence of a sheet at the specific position. Perform certain processing,
An image forming apparatus. The image forming apparatus according to claim 6 or 7,
The processing means is in a state in which the transport operation is performed in a state in which the paper supplied to the paper transport path is transported by the transport operation of the transport means and a printing operation for printing an image on the paper is not performed. When the detection means is in a detection state, the occurrence of a jam is notified as the specific process,
An image forming apparatus. The image forming apparatus according to claim 6, wherein:
In a state in which a printing operation for printing an image on the paper while the paper supplied to the paper conveyance path is conveyed by the conveyance operation of the conveyance unit is performed, the detection result of the processing unit Informing the occurrence of a jam as the specific process when the detection result is different from the detection result by the detection means that should be obtained when the paper is normally transported along the paper transport path by a printing operation;
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 9,
A fixing device for fixing the image transferred onto the paper by passing the paper conveyed along the paper conveyance path between the two rotating members in pressure contact;
A contact pressure adjusting lever for adjusting a contact pressure between the two rotating members;
With
The cover covers a sheet conveyance path formed between the two rotating members, and the contact pressure adjusting lever is moved to the two rotating members as the cover moves from the closed position to the open position. Moving to the side where the contact pressure between
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 9,
A fixing device for fixing the image transferred onto the paper by passing the paper conveyed along the paper conveyance path between the two rotating members in pressure contact;
A contact pressure adjusting lever for adjusting a contact pressure between the two rotating members;
An opening and closing member for opening and closing an opening formed at a position facing the cover in the exterior member of the image forming apparatus;
With
The cover covers a paper conveyance path formed between the two rotating members,
The opening / closing member moves the cover to the closed position side with the movement of the opening / closing member from the open position to the closed position, and the contact pressure adjusting lever is on the side where the contact pressure between the two rotating members is increased. Moving to,
An image forming apparatus.

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