JPH06219588A - Image former - Google Patents

Abstract

PURPOSE:To make proper conveying froce always importable to a slip roll pair in common with both automatic turnover and manual paper feeding operations in an image former that is able to perform both of them. CONSTITUTION:A sheet being fed by a paper feed roll 3 from a paper feed cassette 1 and turned over of both sides by a turnover guide 3, and small-sized cardboard manually inserted by a manual feeding table via a manual inlet port 14 both are conveyed up to a standby roll pair 7 by a common slip roll pair 6. A driven roll 6b of the paired slip rolls 6 is supported by one end of a support member 11 supported free of rotation by a device body, pressure contact force is imparted to these paired slip rolls 6 by a tension spring 12 installed in space between this support member 11 and the manual feeding table 5. Accordingly, this manual feeding table 5 is free of rotation between a manual paper feeding position and a storage position, and at the time of existing in this storage position, the pressure contacting force of the paired slip rolls 6 by the tensile spring 12 becomes weakened to that for thin paper but at the time of existing in the manual feeding position, it comes strong for that of thick paper the other way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer or a copying machine, and more particularly to a function of reversing a sheet on which an image is to be formed and a thick sheet smaller than the sheet. The present invention relates to an image forming apparatus having both a manual sheet feeding function.

[0002]

2. Description of the Related Art FIG. 7 shows the overall configuration of a conventional image forming apparatus (here, a printer is shown as an example). This apparatus includes a sheet feeding cassette 1 as a detachable sheet storage unit in the apparatus main body, a sheet feeding roll 2 as a sheet feeding unit for sequentially feeding the sheets stacked and stored in the sheet feeding cassette 1, A reversing guide 3 is provided as a conveyance guide that guides the fed sheet while reversing it, and a manual feed for introducing a thick sheet such as a postcard smaller than the above-mentioned sheet into the apparatus by a manual feeding operation. An inlet 4 and a rotatable manual feed stand 5 for guiding the small-sized sheet to the manual inlet 4 are provided. The sheet that is inverted and conveyed by the inversion guide 3 and the manual feed inlet 4
Papers that are manually fed in from the above are conveyed by a common slip roll pair 6 to a standby roll pair 7 as a standby means, and once they are on standby, they are transferred to the image forming unit 8 at a predetermined timing. Re-transported. The slip roll pair 6 conveys the paper so as to abut against the standby roll pair 7, and after the paper abuts against the standby roll pair 7, the paper does not convey and continues to rotate in sliding contact with the paper surface. It is a roll pair including a roll 6a and a driven roll 6b.

The image forming section 8 includes a photosensitive drum 8a rotatable in the direction of arrow A, a charger 8b for uniformly charging the entire peripheral surface of the photosensitive drum 8a, and a charged photosensitive drum 8a.
a print head 8c that forms an electrostatic latent image by exposing the surface a to an image based on image information; a developing device 8d that develops the electrostatic latent image with toner to form a toner image on the surface of the photosensitive drum 8a; It has a transfer device 8e for transferring the toner image onto the sheet conveyed through the roll pair 7, a cleaner 8f for collecting the untransferred toner remaining on the surface of the photosensitive drum 8a after the transfer, and the like. The sheet having the toner image on the surface thereof is fixed by the image forming section 8 by passing through the fixing device 9, and then discharged to the outside of the apparatus.

As described above, as the apparatus main body sheet feeding section,
It is common practice to employ a structure in which the paper is fed by the paper feed roll 2 and then reversed by the reversing guide 3 to convey the paper, because this makes it possible to downsize the apparatus. Further, for the thick paper such as postcards in which the reverse feeding is not preferable, the manual feed-in port 4 is provided as described above,
In many cases, for example, a manual feed stand 5 is rotatably mounted in the vicinity thereof. In such a case, since the paper (thin paper) that has been inverted and conveyed or the paper (thick paper) that has been manually inserted is conveyed to the standby roll pair 7, the slip roll pair 6 common to both papers is used. It is preferable in terms of reducing the number of parts, and is currently in practical use.

[0005]

In the image forming apparatus having the slip roll pair 6 common to the reverse feed and the manual feed like the above-mentioned image forming apparatus, the slip roll pair 6 includes the drive roll 6a and the driven roll 6b. The pressure contact force of is always set to be constant. Therefore, even though the paper entry path to the slip roll pair 6 is different between reverse paper feeding and manual paper feeding, the paper feeding function is always the same, and the paper feeding function has the following problems. It was That is, when the pressure contact force of the slip roll pair 6 is set weakly for thin paper (that is, for reverse paper feed), the thick paper fed by hand slips and is not correctly conveyed to the standby roll pair 7,
There was a problem that the image accuracy was disturbed. On the other hand, when the pressure contact force of the slip roll pair 6 is set strongly for thick paper (that is, for manual paper feed), the paper fed reversely is unreasonably applied and the paper is bent. Occurred.

In view of the above conventional problems, it is an object of the present invention to provide an image forming apparatus capable of always providing an appropriate transporting force to a slip roll pair common to reverse sheet feeding and manual sheet feeding. And

[0007]

In order to achieve the above-mentioned object, the present invention has a sheet feeding means for feeding sheets stacked in a sheet storage section and a sheet reversing the sheets fed by the sheet feeding means. The conveyance guide and the sheet that has been inverted and conveyed by the conveyance guide are conveyed so as to contact the standby unit, and after the sheet contacts the standby unit, the sheet slides in contact with the sheet surface without being conveyed and rotates. A pair of slip rolls that continue to rotate, a support member that movably supports the device main body in a direction of pressing the slip roll pair and a direction of separating the pair of slip rolls, and a biasing force that engages the support member and presses the pair of slip rolls. And a biasing member that is provided on the side of the main body of the apparatus, and introduces a manual sheet of a predetermined width, which is smaller than the sheet width that can be fed by the sheet feeding unit, via the slip roll pair. Mouth and hand A manual feed stand, which is provided in the vicinity of the paper feed port and is movable between a manual paper feed position used to guide the manual paper and an unused storage position, is engaged with the support member or the biasing member. An engaging means for moving the support member so that the pressing force of the slip roll pair by the biasing member when the manual feed table is at the manual feed position is higher than the pressing force when the slip roll pair is at the storage position. It is characterized by having.

[0008]

[Operation] When performing reverse paper feeding, the manual feed stand is moved to the storage position. When the manual feed tray is in the storage position, the pressure contact force of the slip roll pair by the biasing member is set weakly for reverse sheet feeding, and an appropriate conveying force for thin sheets can be obtained.

When performing manual paper feeding, the manual feeding stand is moved to the manual paper feeding position. Then, along with the movement, the supporting member supporting the slip roll pair is moved by the engagement means, so that the pressure contact force of the slip roll pair is set to a strong value for manual paper feeding, and as a result, An appropriate conveying force for the paper can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a paper feed unit and its vicinity in an image forming apparatus according to an embodiment of the present invention.
FIG. 6 is a diagram for explaining the operation of each member according to the movement of the manual feed stand in the present embodiment. The same members as those shown in FIG. 7 are designated by the same reference numerals.

In this embodiment, similar to the one shown in FIG. 7, a method is used in which the sheet is fed upside down after being fed in a cassette, and a manual sheet feeding function for thick paper is provided. Is assumed. That is, a paper feed cassette 1 as a paper storage unit, a paper feed roll 2 as a paper feed unit, and a reversal guide 3 as a conveyance guide for reversing the fed paper to convey it are provided. It is provided with a manual feed-in port 4 for manually inserting a small-sized thick paper and a manual feed stand 5 provided in the vicinity of the manual feed-in port 4, and a sheet reversely fed by the reversing guide 3 and The sheet manually fed from the manual feed inlet 4 is configured to be conveyed by a common slip roll pair 6 (driving roll 6a and driven roll 6b) to a standby roll pair 7 as a standby unit. ing. It should be noted that the configuration after the standby roll pair 7, that is, the configuration of the image forming unit, the fixing device, and the like, may be the same as that shown in FIG.

In the present embodiment having the above-mentioned structure, when the manual feed tray 5 is used for manual paper feed and the manual paper feed position (the position shown in FIGS. 1 and 2C) is not used. So that it can be moved to and from the storage position (the position shown in FIG. 2 (a)), it is rotatably supported on the main body of the apparatus about the support shaft 5a in the direction of arrow B, and as shown below. 5
It is characterized in that the pressure contact force of the slip roll pair 6 is made variable by the rotation of.

As means for varying the pressure contact force of the slip roll pair 6, first, the driven roll 6b of the slip roll pair 6 is rotatably supported by one end of an arm-shaped support member 11, and the driven roll 6b is also supported. In order to be movable in a direction in which it is pressed against the drive roll 6a and a direction in which it is separated from the drive roll 6a, a structure is provided in which the support body 11 is rotatably supported in the direction of arrow C about the support shaft 11a at the other end. is there. Further, the hooks 5 are provided at predetermined positions on the manual feed stand 5 and the support member 11, respectively.
b and 11b are provided, and one end and the other end of the tension spring 12 as a biasing member are hooked to the hooking portions 5b and 11b, respectively, so that the driven roll 6b is pressed against the drive roll 6a via the support member 11. It is configured to bias in the direction.

Here, the hooking portion 5b as an engaging means for engaging with the tension spring 12 rotates around the support shaft 5a as the manual feed stand 5 rotates, but the arrangement of the hooking portion 5b is not limited to this. The installed position is a position where the pressure contact force of the slip roll pair 6 due to the biasing force of the tension spring 12 becomes stronger when the manual feed table 5 is at the manual feed position than at the stored position. Along with the above-mentioned rotation, when the hooking portion 5b is on the line a connecting the support shaft 5a and the hooking portion 11b, it moves upward and downward with respect to the dead point, so that the manual feed tray 5 can be moved. Is set to a position where it is biased toward the storage position and the manual feed position. That is, the manual feed stand 5
2A is in the storage position as shown in FIG. 2A, the hook portion 5b is positioned above the line a, and in this state, the urging force of the tension spring 12 causes the support member 11 to move. A relatively weak pressure contact force (this pressure contact force is referred to as F ₁ ) is applied to the slip roll pair 6 via the slip roll pair 6 and the manual feed stand 5 is biased in a direction to be held at the storage position. On the other hand, the manual stand 5 is shown in FIG.
As shown in FIG. 3, when the manual feed position is set, the hook portion 5b is located below the line a and the tension spring 12
Is in a more extended state than in the storage position, and in this state, the biasing force of the tension spring 12 exerts on the slip roll pair 6 via the support member 11 a larger pressure contact force than in the storage position ( Let this pressure contact force be F _2.
2 > F ₁ ) and urge the manual feed stand 5 in a direction to hold it at the manual feed position.

The main operation in each paper feed mode in the image forming apparatus having the above-mentioned configuration will be described below with reference to FIG. First, when feeding paper from the paper feed cassette 1, the manual feed stand 5 is set to the storage position as shown in FIG. Then, for example, a cassette sheet feed mode is set by a switch (not shown) or the like that engages with the manual feed stand 5. In this case, the hook portion 5b is located above the line a as described above, and the biasing force of the tension spring 12 in this state applies a relatively weak pressure contact force F ₁ to the slip roll pair 6. This pressure contact force F ₁ is applied to the reversing guide 3 after the cassette is fed.
Optimal pressure contact force for thin paper that has been reversed and conveyed.

On the other hand, when performing manual paper feed using the manual feed stand 5, the manual feed stand 5 is rotated from the above-mentioned storage position to the manual feed position, and the state shown in FIG. After that, as shown in FIG. 2C, the manual feed stand 5 is set at the paper feed position. Then, the switch (not shown) and the manual feed stand 5 are disengaged, and the cassette paper feed mode is switched to the manual paper feed mode. In this case, the hooking portion 5b is located below the line a as described above, and the tension spring 12 is further stretched, and the biasing force of the tension spring 12 in this state strengthens the slip roll pair 6. The pressure contact force F ₂ (> F ₁ ) of is given. The pressure contact force F ₂ is an optimum pressure contact force for a small-sized thick sheet that is manually inserted by using the manual feed stand 5.

Therefore, according to the present embodiment, the magnitude of the pressure contact force of the slip roll pair 6 can be switched according to the opening / closing of the manual feed stand 5, so that thin paper can be used during cassette paper feed (reverse paper feed). Optimum conveyance force is obtained, and when manually feeding, it is possible to obtain the optimum conveyance force for small size thick paper, and as a result, problems such as poor paper conveyance and bending that have occurred in the past are brilliant. Can be resolved.

Next, FIG. 3 shows another embodiment of the present invention.
In the above embodiment, the hooking portion 5b provided on the manual feed stand 5 is adopted as the engaging means for engaging with the tension spring 12, but in the present embodiment, the engaging means for engaging with the support member 11 is adopted. There is. That is, one end of the tension spring 12 is
In the same manner as the above-mentioned one, the other end is hooked on the support member 11, and the other end is hooked on the main body of the apparatus.
c is provided and a convex portion 5c is provided on the manual feed table 5, and the concave portion 11c and the convex portion 5c are engaged with each other when the manual feed table 5 is set at the manual feed position as shown in FIG. 3C. By doing so, the convex portion 5c serves as an engagement means that engages with the support member 11. Here, as shown in FIG. 3 (a), when the concave portion 11c and the convex portion 5c are disengaged by setting the manual feed stand 5 to the storage position, the slip roll pair is driven by the urging force of the tension spring 12. A relatively weak pressure contact force F ₁ for thin paper is applied to the sheet 6, and the concave portion 11c and the convex portion 5c are engaged by setting the manual feed stand 5 to the manual feed position as shown in FIG. 3 (c). If matched, convex part 5c
Becomes a state in which the concave portion 11c is slightly pushed upward, and the support member 11 is urged in a counterclockwise direction about the support shaft 11a. As a result, the slip roll pair 6 has a strong press contact force F ₂ (for thick paper). > F ₁ ) is given. In this way, it is possible to obtain the same effect as the above embodiment.

An example of the manual feed stand 5 suitable for use in each of the above embodiments is shown in FIGS. The manual feed tray 5 is for manually feeding paper of a postcard size or smaller, and the maximum usable paper width d (FIG. 4) is about 120 mm which is the width of the postcard. The manual feed table 5 is a paper loading table 21 that is rotatably attached to the apparatus main body between a storage position and a manual paper feeding position, and a paper guide that can slide symmetrically on the paper loading table 21. The pair of guide members 22 and 23 and the film-shaped tape member 2 as a connecting member which is provided on the back surface side of the sheet placement table 21 and moves the guide members 22 and 23 in conjunction with each other.
It is composed of 4, 25 and the like. Guide members 22, 23
As shown in FIG. 6, the guide member main bodies 22a and 23a arranged on the sheet placing table 21 and the guide member main body 22 integrally formed with the guide member main bodies 22a and 23a.
a and 23 a, which are made up of support members 22 b and 23 b for supporting the paper loading table 21 from the back side of the paper loading table 21,
It is assembled so as to be slidable along the slit 21a provided in the. As shown in FIG. 5, the tape members 24 and 25 are provided with supporting members 22b and 23b via pulleys 26 and 27 provided near the ends of the slit 21a, respectively.
The tape member 24 is bridged from one side to the other, that is, the hole provided at one end of the tape member 24 is hooked on the projection 22c of the support member 22b and the hole provided at the other end is projected from the support member 23b. The hole provided at one end of the tape member 25 is engaged with the protrusion 23d of the support member 23b, and the hole provided at the other end is engaged with the protrusion 22d of the support member 22b. ing.

When the guide member 22 is to be moved outward in the manual feed table 5 having such a structure, as shown by an arrow in FIG. 5A, the other guide member is inserted via the tape member 25. 23, a movement to move the guide member 22 to the outside is generated, which in turn causes a movement to move the guide member 22 to the outside via the tape member 24. 23
Move in conjunction with each other and move outward. The same can be said for the case where the other guide member 23 is to be moved outward. Further, when the guide member 22 is to be moved inward, as shown by the arrow in FIG. 5B, the other guide member 2 is inserted via the tape member 24.
A movement for moving the guide member 22 inward is generated, and this movement in turn causes a movement for moving the guide member 22 inward via the tape member 25. As a whole, the two guide members 22, 23 interlocks and moves inward. The same applies to the case where the other guide member 23 is moved inward.
In this way, the two guide members 22 and 23 are interlocked with each other and move symmetrically, so that the manually fed sheet can be guided into the apparatus while being restricted to the central position on the sheet placing table 21.

According to the manual feed table 5 having such a structure, particularly when the tape members 24 and 25 are simply hung from one of the support members 22b and 23b to the other at the time of assembling, the conventional manual feed table 1 There is no need for the troublesome operation of hooking two long belt-shaped members in a single turn, and there is an advantage that the assembly work becomes very easy.

The present invention is not limited to the printer device shown in FIG. 7, but may be used for other image forming such as a copying machine or a facsimile device as long as it has both the reverse paper feeding function and the manual paper feeding function. It is also applicable to devices.

[0023]

According to the present invention, since the magnitude of the pressure contact force of the slip roll pair can be switched according to the movement of the manual feed stand, it is possible to obtain the optimum conveying force for thin sheets during reverse sheet feeding. It is possible to obtain the optimum feeding force for small and thick papers by manual feeding, and therefore, regardless of reverse feeding and manual feeding, there is no problem such as defective feeding or bending of the paper, and it is always stable. A transfer capacity can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a sheet feeding unit and its vicinity in an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of each member according to the movement of the manual feed stand in the embodiment shown in FIG. 1, (a)
Shows the state when the manual feed tray is at the storage position, (b) shows the state when the manual feed tray is at an intermediate position between the storage position and the manual feed paper feed position, and (c) shows the manual feed tray where the manual paper feed feeds. Shows the state when in the position.

FIG. 3 is a diagram for explaining the operation of each member according to the movement of the manual feed stand in the image forming apparatus of another embodiment of the present invention, and FIG. 3A is a state when the manual feed stand is at the storage position. FIG. 7B shows a state when the manual feed tray is at an intermediate position between the storage position and the manual paper feed position, and FIG. 7C shows a state when the manual feed stand is at the manual paper feed position.

FIG. 4 is a perspective view showing an example of a manual feed stand.

5A and 5B are views of the manual feed table shown in FIG. 4 as viewed from the back side, FIG. 5A showing a movement when the guide member is moved to the outside, and FIG. 5B a case where the guide member is moved to the inside. Shows the movement of.

6 is an exploded view of the manual feed stand shown in FIG. 4. FIG.

FIG. 7 is an overall view of a conventional image forming apparatus.

[Explanation of symbols]

 1 Paper feed cassette 2 Paper feed roll 3 Reversing guide 4 Manual feed inlet 5 Manual feed stand 5a Support shaft 5b Locking part 5c Convex part 6 Slip roll pair 7 Standby roll pair 11 Support member 12 Tension spring

Claims (1)

[Claims] 1. A paper feed unit for feeding paper stacked in a paper storage unit, a conveyance guide for reversing the paper fed by the paper feed unit, and an inverted conveyance by the conveyance guide. A sheet is conveyed so as to contact the standby means, and after the sheet comes into contact with the standby means, the slip roll pair is kept in sliding contact with the surface of the sheet without being conveyed, and the slip roll pair continues to rotate. And a support member that is movably supported in the apparatus main body in a separating direction, an urging member that engages with the support member and urges the slip roll pair in a pressure contacting direction, A manual paper feed opening for introducing a manual paper of a predetermined width smaller than the paper width that can be fed by the paper feed means through a slip roll pair, and a manual paper feed provided near the manual paper feed opening. Guide A manual feed stand that is movable between a manual feed position used for storing and a storage position that is not used, and when the manual feed stand engages with the support member or the biasing member and the manual feed stand is at the manual feed position. An image forming apparatus, comprising: an engaging unit that moves the support member so that a pressure contact force of the slip roll pair by the biasing member is higher than a pressure contact force at the storage position.