JP2002012342A - Paper guide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the drifting of paper to be carried through a carriage path by using a simple mechanism. SOLUTION: The carriage path is provided with a first detecting element 20 for detecting the paper at its end, a guide member 21 freely set in and out of the carriage path for preventing the drifting the paper, and a second detecting element 22 for detecting the passage of the paper at its rear end, in sequence along the direction of carriage. Each of the detecting elements 20, 22 and the guide ember 21 are connected to each other via a link member 31. When the first detecting element 20 detects that the paper exists, the guide member 21 is in set-out attitude. When the paper passes through the guide member 21 within a paper size, the guide member 21 is changed into set-in attitude. The guide member 21 out of the paper size remains in set-out attitude, with resultant contact with the side end of the paper to restrict the drifting of the paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet guide device for guiding a sheet so as not to be skewed when the sheet is conveyed in a sheet conveying path in an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine in which these are integrated, an image is formed on a sheet while conveying the sheet. The paper is transported in the transport path by transport rollers, belts, and the like.If the paper is skewed at this time, image transfer deviation and fixing deviation occur, or the skewed paper is caught on other members. Paper jams and stacking failures of the discharged paper. Therefore,
In order to prevent the paper from being skewed, the above problem is solved by adjusting the load of a spring for pressing the transport roller against the paper, setting the roller diameter, and the like to adjust the balance of the paper transport.

Further, a guide member is provided for a sheet to be conveyed, and a side edge of the sheet is regulated, thereby preventing oblique feeding. For example, Japanese Patent Application Laid-Open No. Hei 9-71328 discloses that a guide member movable in the width direction of a sheet is provided, and the guide member is fixed at a position corresponding to the sheet size to restrict the oblique feeding of the sheet.

[0004]

As described above, it is not easy to set according to the change due to the type of paper by adjusting and setting the transport rollers, and it is not easy to set at the design and development stage. The process is complicated and difficult, and time-consuming, so too costly. In addition, due to variations in the manufacture and mounting of the transport rollers, or differences in the types of paper such as paper quality and paper thickness, the specifications may not be as set, and the oblique feeding of the paper cannot be reliably prevented.

When a guide member is used, it can be easily moved when it is placed on a paper feed cassette or a manual feed tray. However, when it is placed on a transport path, the guide member is positioned according to the sheet size. Must be, and manually difficult.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a paper guide device which can prevent a sheet conveyed in a conveyance path of an image forming apparatus from being inclined by a simple mechanism.

[0007]

Means for Solving the Problems According to the present invention, a guide member is provided so as to be able to protrude and retract in a conveying path on which a sheet is conveyed so as to prevent the sheet from being skewed. Accordingly, the guide member is set in a protruding posture in which the guide member protrudes into the conveyance path so as to contact the side edge of the sheet. The guide members may be arranged at positions corresponding to the respective paper sizes.

Here, the posture of the guide member is switched in accordance with the presence or absence of a sheet. When there is a sheet, the guide member is set in a retracted posture retracted from the transport path so as not to hinder the advance of the sheet. Then, the guide member located at the side end of the sheet is set in a protruding posture to prevent the sheet from advancing in an oblique direction.

[0009] Specifically, a transport path on which a sheet is transported is:
A first detecting element for detecting the leading edge of the sheet, a guide member which can freely move in and out of the conveying path to prevent the sheet from being skewed, and a second detecting element for detecting passage of the trailing end of the sheet in the conveying direction. The guide members are provided in this order along with the operation of each detection element, and the guide members are moved in and out in conjunction with the operation of each detection element.

When each detecting element detects the presence of a sheet, the guide member is set to the protruding posture, and when each detecting element detects the absence of the sheet, the guide member is set to the retracted posture. Also, the guide member is
When it is in the protruding position, it is movably supported so as to change to the immersing position by the load of the sheet. That is, the guide member is urged in a projecting direction by a spring, and the urging force of the spring is set so as to project into the conveyance path when there is no load, and to retreat when a sheet load is applied. Therefore, the posture of the guide member can be switched by a simple mechanism.

As described above, the first detecting element detects the presence of the sheet, so that the system for regulating the conveyance of the sheet is prepared. When the sheet passes through the guide member, the guide member within the sheet size is immersed. Be in a posture and do not disturb the paper advance. The guide member outside the sheet size is in a protruding posture and comes into contact with the side edge of the sheet, restricting the movement of the sheet in an oblique direction, thereby preventing the oblique feeding.

When the trailing edge of the sheet passes through the first detecting element, the first detecting element detects the absence of the sheet, but the second detecting element detects the presence of the sheet. As a result, it is possible to prevent the sheet being fed obliquely from being fed. When the trailing end of the sheet passes through the guide member, the load of the sheet on the guide member is removed, and the guide member is in the protruding posture. At this time, since it is not necessary to regulate the conveyance of the sheet, the guide member may be in the protruding posture. When the trailing edge of the sheet has passed through the second detection element, the second detection element detects the absence of the sheet, the guide member assumes the immersion posture, and retreats from the transport path.

[0013]

FIG. 1 shows a schematic configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention. First, image information in the image forming apparatus is obtained by, for example, reading a document image by an image reading device or transmitting the image from a terminal device on a network such as a personal computer. Then, based on the print request, a laser beam is emitted from the optical unit 1 to the photoconductor 2 according to the image information, and an electrostatic latent image is formed on the photoconductor 2. The electrostatic latent image is developed and visualized by the developer supplied from the developing device 3. The toner image in which the image information is visualized in this way is transferred onto the sheet by applying a transfer voltage from the back of the sheet by the transfer device 4. When the sheet passes through the fixing device 5, the unfixed toner is melted in a bath by heat and fixed to the sheet to fix the toner image. Thereafter, the paper is discharged to the paper discharge tray 6. In the figure, reference numeral 7 denotes a cleaning device.

On the other hand, when a print request is made,
The paper size is determined based on the relationship between the image size and the magnification set at the time of the print request, the paper cassette 8 containing the paper of the paper size is selected, and the paper is supplied from here. Alternatively, paper can be placed on the manual feed tray 9 and supplied, and both can be selected, and the user may select it when a print request is made.

The sheet thus selected is fed by pickup rollers 10 and 11, and is conveyed to idle roller 12 by a conveying roller (not shown). At this time, the sheet is temporarily stopped by the idle roller 12, and the leading edge of the sheet and the leading edge of the image are aligned and transported again in synchronization with the timing of image formation on the photosensitive member 2. The toner image is transferred from the photoreceptor 2 onto the sheet after passing between the photoreceptor 2 and the transfer device 4, and the sheet is transported to the fixing device 5 by a transport belt (not shown). While the sheet is being conveyed by the fixing roller of the fixing device 5, the toner image is fixed on the sheet, and is discharged to the discharge tray 6 by a discharge roller (not shown).

Therefore, the transport path for transporting the paper is between the paper feed cassette 8 and the idle roller 12, between the manual feed tray 9 and the idle roller 12, between the idle roller 12 and the transfer device 4, and the transfer path. It is formed between the device 4 and the fixing device 5 and between the fixing device 5 and the sheet discharge tray 6. Each transport path is constituted by a guide plate 13, and a roller, a notch hole formed in the guide plate 13,
A belt or the like is provided so as to face the transport path, and the paper can be transported.

When a sheet is conveyed through the conveyance path, when the size of the sheet requested to be printed is small, that is, when the width in the direction orthogonal to the direction of travel of the sheet is small, the sheet is likely to be skewed. Therefore, a sheet guide device is provided in the transport path to prevent the sheet from being skewed.

As shown in FIG. 2, the paper guiding device includes a first detecting element 20 for detecting the leading edge of the paper, a guide member 21 which can be moved into and out of the transport path to prevent the paper from being skewed, and Second detection element 22 for detecting the passage of the trailing edge of the sheet
And interlocking means for switching between a protruding posture in which the guide member 21 protrudes into the transport path and a retracted attitude in which the guide member 21 is retracted from the transport path in conjunction with the operation of each of the detection elements 20 and 22.

A first hole 23, a center hole 24, and a second hole 25 are formed in the guide plate 13 of the transport path in order from the upstream side in the transport direction, and the first detecting element 20 is moved from the first hole 23 into the transport path. Similarly, the second detection element 22 is disposed in the second hole 25, and the guide member 21 is disposed so as to protrude and retract from the center hole 24.

The first detecting element 20 comprises a lever rotatably supported around a support shaft 26 provided on a frame of the image forming apparatus, and is mounted so as to protrude in a direction opposite to the conveying direction. Therefore, the leading end is formed in a mountain shape so that the conveyed sheet is not caught. Similarly, the second detecting element 22 also includes a lever rotatably supported around the support shaft 27.

The guide member 21 is supported so as to move up and down with respect to the frame, and a tension spring 30 is interposed between the lower end of the guide member 21 and the frame to urge the guide member 21 downward. That is, in the initial state, the guide member 21 is held in the retracted posture by the urging force of the extension spring 30. Further, the leading end surface of the guide member 21 protruding into the transport path is formed into a curved surface having a large curvature so as not to obstruct the passage of the sheet.

Each of the detecting elements 20 and 22 and the guide member 21 are connected via a link member 31, respectively. The link member 31 is formed integrally with the ends of the detection elements 20 and 22, and one end of the link member 31 is attached to the center shaft 32 held by the guide member 21. The guide member 21 has a vertically elongated through hole 3
The center shaft 32 is inserted through the through hole 33, and the compression spring 3 is attached to the top surface of the through hole 33.
4 suspends the central shaft 32. As a result, the center shaft 32 and the guide member 21 can move up and down relatively.

The link member 31 and the compression spring 34 constitute an interlocking means, and as shown in FIG.
When each of the detecting elements 20 and 22 detects the presence of a sheet, the guide member 21 is set to the protruding posture, and when it is detected that there is no sheet, the guide member 21 is set to the immersion posture. That is, when the detection elements 20 and 22 detect the presence of a sheet, the detection elements 20 and 22 are pressed by the sheet and rotate downward, and the link member 31 also rotates in the same direction. The shaft 32 is raised, and the guide member 21 is lifted to be in a protruding posture. When there is no paper, the detecting elements 20 and 22 project into the transport path, one end of the link member 31 is at a lowered position, and the guide member 21 is biased by the tension spring 30.
Is held in an immersive position.

Here, the guide member 21 is urged in a projecting direction by a compression spring 34 when in the projecting position, but can move up and down with respect to the center shaft 32.
By the way, when the paper passes above the guide member 21 and the guide member 21 protrudes into the conveyance path, the advance of the paper is prevented. What is necessary is just to make it an immersive posture so that it may not become. Therefore, the urging force of the spring 34 is
When a load is applied to the sheet, the sheet is set so as to be retracted from the transport path to be in the immersion posture. Therefore, when the sheet passes over the guide member 21, the guide member 21 descends due to the load, and does not hinder the advance of the sheet.

Then, the plurality of guide members 21 are
As shown in (1), they are arranged in parallel in the transport path in parallel with the transport direction according to the paper size. A fixed guide member 35 corresponding to one side end of the sheet is fixed to the guide plate 13. With the fixed guide member 35 as a reference position, the fixed guide member 35 corresponds to the length and width of each sheet size such as a postcard size, a B5 size, an A4 size, and the like. Guide members 21 are arranged at the respective positions. At this time, the length of the side surface of the fixed guide member 35 and the inner surface of the guide member 21 facing the fixed guide member 35 have a length corresponding to the paper size, and the other side end of the paper comes in contact with the inner surface of the guide member 21. It is possible. In addition, each detection element 2
Reference numerals 0 and 22 are arranged on the inner surface side of the guide member 21, that is, closer to the fixed guide member 35 than the guide member 21.

The paper guide device is provided between the pickup rollers 10 and 11 and the idle roller 12, but is provided between the idle roller 12 and the transfer device 4.
It is installed between the transfer device 4 and the fixing device 5 and between the fixing device 5 and the paper discharge roller. Alternatively, it may be installed in at least one of the above locations.

In the arrangement of the guide members 21, the fixed guide member 35 is set as a reference position with reference to one side of the sheet, but a pair of guide members 21 is set for each sheet size with reference to the center of the sheet. They may be arranged at predetermined intervals. The detection elements 20 and 22 are arranged at positions within the sheet size for each sheet size so that the detection elements 20 and 22 can always contact the sheet, and the guide member 21 is arranged at a position outside the sheet size.

Next, the behavior when the conveyed sheet passes through the sheet guide device will be described. For example, FIG.
The guide member 21 is arranged as shown in FIG. This is a case where the guide member 21 is installed with reference to the center of the sheet, and the guide member 21 is arranged so as to contact both side edges of the sheet. First, in the initial state before the paper is conveyed, as shown in FIG. 7A, each of the detection elements 20 and 22 protrudes into the conveyance path, and the guide member 21 is in the immersion posture.

When the sheet is conveyed and its leading end contacts the first detection element 20, the presence of the sheet is detected, and FIG.
As shown in (b), the first detection element 20 descends. In conjunction with this, the guide member 21 rises and assumes a protruding posture. At this time, the second detection element 22 also descends as the central axis 32 rises. Note that the detection element 2 outside the paper size
Since the sheet does not come into contact with 0, the guide member 21 is held in the immersion posture.

As shown in FIG. 6, when the conveyed sheet passes above the guide member 21 in the protruding position,
The paper travels over the smooth upper surface of the guide member 21 without being caught on the paper. And the guide member 21
Is pushed down by the load of the sheet as shown in FIG. Since the guide member 21 only descends with respect to the central axis 32 and the central axis 32 does not move, the respective detection elements 20 and 22 remain lowered.

At this time, among the guide members 21 arranged at the respective positions A, B, C and D in FIG. 5, the guide members 21 arranged at the positions B and C within the sheet size are And descends so as not to obstruct the passage of the sheet as shown in FIG. On the other hand, since the paper does not contact the guide members 21 arranged at the positions A and D outside the paper size, as shown in FIG.
Is held in the protruding position until the sheet passes through the second detection element 22. However, since the sheet is in contact with each of the detection elements 20 and 22, the detection elements 20 and 22 are lowered.

Therefore, when the sheet passes through the sheet guide device, the side end of the sheet comes into contact with the protruding guide member 21 and is guided in the transport direction without shifting from the reference position. Therefore, when the sheet is conveyed obliquely, the guide member 21 restricts the advance in the oblique direction, thereby preventing the oblique feeding.

Then, the sheet is further conveyed, and FIG.
As shown in (a), when the trailing edge of the sheet passes through the first detecting element 20, the load of the sheet applied to the first detecting element 20 disappears, but the load of the sheet is still applied to the second detecting element 22. ing. Therefore, the second detection element 22 maintains the lowered state, the central axis 32 does not move, and the first detection element 20 does not move up. The paper is further conveyed, and FIG.
As shown in (b), when the trailing edge of the sheet passes through the guide member 21, the load of the sheet on the guide member 21 disappears, and the guide member 21 is moved with respect to the center shaft 32 by the urging force of the compression spring 34. It moves to a protruding posture.

When the trailing edge of the sheet passes through the second detection element 22, the absence of the sheet is detected, and as shown in FIG. 8C, the load on the second detection element 22 is removed.
The second detection element 22 rises so as to protrude into the transport path. Accordingly, the central shaft 32 moves down, the first detecting element 20 moves up, and the guide member 21 moves down to the immersion posture.

As described above, the first member is sandwiched between the guide members 21.
By disposing the detecting element 20 and the second detecting element 22, even if the trailing end of the sheet passes through the first detecting element 20 and detects the absence of the sheet, the second detecting element 22 detects the presence of the sheet. Therefore, the immersion posture of the guide member 21 can be maintained. Here, when the first detection element 20 detects that there is no paper, the paper is still passing above the guide member 21, but when the guide member 21 changes from the immersion posture to the protruding posture, the paper is lifted, There is a problem in that the guide member 21 that is in contact with the side edge of the paper and restricts the paper does not come into contact, and the effect of the restriction is lost. However, even if the first detection element 20 detects that there is no paper, the second detection element 22 detects that there is paper, so that the guide member 2
1 is not switched, and the above problem does not occur.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. For example, a detection element for detecting the presence / absence of a sheet is provided independently of the guide member, and is disposed upstream and downstream in the sheet conveyance direction with the guide member interposed therebetween. A moving means for projecting inward is provided. As the moving means, the guide member may be moved up and down by a motor, a solenoid or the like, and the timing of the up and down movement is the same as in the above embodiment.

Instead of providing a guide member for each paper size, one guide member may be moved by a well-known linear moving mechanism in a direction perpendicular to the transport direction. The number of guide members can be reduced by moving the guide members according to the paper size based on an output signal from a size detector for detecting the paper size or a print request of the image forming apparatus. In this case, the guide member and the first and second detection elements may be moved as one unit.

When the image forming apparatus has a double-sided printing function, an intermediate tray is provided. Therefore, a sheet guide device may be provided in a transport path between the fixing device and the intermediate tray. Further, the paper is not limited to the paper for printing, and may be a document, and a paper guide device may be provided in a transport path of an image reading apparatus that automatically transports the document.

[0039]

As is apparent from the above description, according to the present invention, by providing the guide member for switching the posture depending on the presence or absence of the sheet, the guide member located at the side end of the sheet size projects into the conveyance path. As a result, the sheet is prevented from traveling in the oblique direction, and the sheet can be prevented from being fed obliquely.

Therefore, the paper can be transported in a straight state along the transport direction, and problems such as image transfer deviation and fixing deviation, paper jam due to oblique feeding, and defective stacking of discharged paper can be prevented. can do.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIGS. 2A and 2B show a paper guide device, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is a diagram illustrating a state of a paper guide device when paper presence is detected.

FIG. 4 is a diagram showing an arrangement of guide members.

FIG. 5 is a plan view of the paper guide device before the paper passes.

FIG. 6 is a plan view of a paper guide device during paper passage.

FIGS. 7A and 7B are diagrams for explaining the behavior of the paper guide device with the advance of the paper, where FIG. 7A is the initial state, FIG. 7B is when the first detection element detects the leading edge of the paper, and FIG. Diagram showing when paper passes through a guide member

FIGS. 8A and 8B are diagrams for explaining the behavior of the paper guide device with the advance of the paper, wherein FIG. 8A shows when the rear end of the paper has passed the first detection element, and FIG. (C) shows a state in which the trailing edge of the sheet has passed through the second detection element.

FIG. 9 is a diagram illustrating a state of a guide member outside a sheet size.

[Explanation of symbols]

 Reference Signs List 20 first detecting element 21 guide member 22 first detecting element 30 tension spring 31 link member 32 center axis 34 compression spring P paper

Continuing on the front page (72) Inventor Yasumasa Morimoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Nobuyuki Kimoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F term (reference) 3F048 AA01 AB01 BA20 CB03 CC03 CC04 DB01 EB21 EB31 3F101 FA06 FB04 FE01 FE11 LA01 LB03 3F102 AA01 AB01 BA02 BB04 CB01 DA05 EA03 FA03

Claims (7)

[Claims] 1. A moving means for protruding and retracting a guide member in a conveying path on which a sheet is conveyed so as to prevent the sheet from being obliquely fed, and for projecting the guide member into the conveying path according to the sheet size. A paper guide device, comprising: 2. The paper guide device according to claim 1, wherein a plurality of guide members are used according to the paper size, and each guide member is arranged at a position corresponding to each paper size. 3. A first detecting element for detecting a leading edge of a sheet, a guide member which is capable of protruding and retracting in the conveying path to prevent the sheet from being skewed, on a conveying path along which the sheet is conveyed, and A sheet guide device, comprising: a second detection element for detecting the passage of the end; and interlocking means for interlocking the guide member depending on the presence or absence of a sheet, in conjunction with the operation of each detection element. 4. An interlocking means, wherein when each of the detecting elements detects the presence of a sheet, the guide member has a protruding position in which the guide member protrudes into the conveyance path, and when the absence of a sheet is detected, the guide member is retracted from the conveyance path. 4. The apparatus according to claim 3, wherein the guide member is movably supported so that the guide member changes to a retracted posture by a load of the sheet when the guide member is in the protruded posture.
Paper guide device according to the above. 5. Each detecting element is supported so as to be movable depending on the presence or absence of a sheet, and the interlocking means is constituted by a pair of link members connecting each detecting element and the guide member, respectively. When the presence of paper is detected, the guide member assumes a protruding posture in conjunction with the movement, and when the first detection element detects the absence of paper and the second detection element detects presence of paper, the guide member protrudes. The paper guide device according to claim 3, wherein the guide member is brought into a retracted posture in conjunction with the movement when the second detection element detects that there is no paper. 6. The sheet guide device according to claim 3, wherein each guide member is arranged at a position corresponding to the sheet size so as to be able to contact a side edge of the sheet to be conveyed. 7. A sheet placement section for feeding a sheet, an idle roller for conveying the sheet to the photoconductor at a predetermined timing, a transfer section for transferring an image formed on the photoconductor to the sheet, and an image on the sheet. An image forming apparatus comprising: a fixing unit for fixing the paper; and a storage unit for storing the sheet after the fixing, and a conveyance path from the sheet placement unit to the storage unit via the idle roller, the transfer unit, and the fixing unit. The sheet guide device according to claim 1, wherein the sheet guide unit is disposed between the sheet placement unit and the idle roller, between the idle roller and the transfer unit, between the transfer unit and the fixing unit, and between the fixing unit and the storage unit. An image forming apparatus, wherein the image forming apparatus is installed in at least one of the following.