JP2003118911A - Sheet discharge mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a counter-smear mechanism reducing feed resistance. SOLUTION: The mechanism includes two lines of paper discharge rollers; a first guide member serving as a member for guiding a transverse end of a sheet between the paper discharge rollers and being movable between a first position where it protrudes into a sheet feed path to guide the sheet end upwards and a second position where it moves back from the sheet feed path; and a second guide member by which the sheet end guided upwards by the first guide member is guided further upwards at a position downstream of the first guide member along feed direction to curve the sheet inwards in its transverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and in particular, when a sheet after recording is discharged, disturbance or stain (hereinafter referred to as smear) of a recorded image due to rubbing between discharged sheets is prevented. Sheet discharge mechanism.

[0002]

2. Description of the Related Art An image forming apparatus using an ink jet recording system includes a plain paper as a recording medium or a sheet coated with an ink receiving layer which positively receives ink in advance (paper for exclusive use of ink jet (coated paper, glossy paper, Since it can print on various media such as glossy film, OHP sheet, etc.) at high density and at high speed, it is widely used as a printing device such as a printer, a facsimile, and a copying machine.

However, the ink used in the ink jet recording system uses water as a main solvent, and plain paper or the like having no ink receiving layer that positively receives the ink is continuously discharged. When rubbing between sheets occurs, smear may occur due to unfixed ink.

As a means for solving such a problem, a member for guiding the left and right end portions of the paper near the paper discharge roller is used to bend the paper in a concave shape to give a waist, thereby removing the discharged sheet. A mechanism that prevents the leading edge from sagging, rubbing against the surface of the previously discharged sheet, disturbing the unfixed image portion, and preventing unfixed ink from transferring to the transport path surface of the discharged sheet is provided. Japanese Patent Laid-Open No. 08-0406
20 and the like.

Such a conventional sheet discharging mechanism will be described with reference to FIG. In FIG. 8, the sheet S fed from the sheet feeding unit 51 is conveyed by the conveying roller 52 to the recording unit 5.
The sheet S, which has been conveyed to No. 3, and on which the recording has been performed, is discharged to the discharge tray 58 via the first discharge roller pair 54 and the second discharge roller pair 55. Further, a spring-biased guide member 56 is provided between the first paper ejection roller 54 and the second paper ejection roller 55 and near both ends in the width direction of the ejected sheet, as shown in FIG. By providing a concave curve in the width direction of the sheet, the sheet is provided with a waist and the sheet is ejected without hanging down. In addition, thick sheets and strong sheets (glossy paper, glossy film, O
HP sheet, etc.) is used, it is difficult to lift the left and right end portions of the sheet to bend the sheet into a concave shape, and when it is attempted to forcibly give a concave curvature, it causes considerable conveyance resistance. turn into. Therefore, when such a seat is used, the spring bias of the guide member 56 loses the rigidity of the seat, and FIG.
By retreating from the transport path as shown in (4), the concave curve is not applied. Moreover, many such thick or highly rigid sheets have an ink receiving layer, and because of their originally good ink fixing properties, many sheets do not require smear countermeasures. Further, even if it does not have an ink receiving layer, it can be supported by two rows of paper ejection roller pairs of the first paper ejection roller pair 54 and the second paper ejection roller pair 55,
The sheet can be held without hanging down.

[0006]

However, in such a conventional technique, a sheet having a weak stiffness (plain paper, etc.) is used.
In order to impart a concave curve in the width direction and prevent the tip from hanging down, it is necessary to secure a certain projection height of the guide member from the paper transport path. At this time, in the case of a thick sheet or a strong sheet, the spring bias of the guide member loses to the waist of the sheet, and the amount of protrusion of the guide member from the conveyance path decreases to the side where As the amount of compression increases (in the case of a compression spring), its urging force increases. As a result, the sliding load between the guide member and the back surface of the thick sheet becomes large, and the conveyance accuracy is disturbed, and the lifting force of the sheet end portion by the guide member causes the recording portion located upstream of the first-row paper ejection roller. And the distance between the recording means and the sheet is narrowed, which causes image disturbance and contact between the recording means and the sheet.

Therefore, in order to solve the above-mentioned problems, an object of the present invention is to impart a concave curve in the width direction to a sheet having a weak stiffness (plain paper, etc.) by a guide member.
Provide a conveyance path with reduced conveyance resistance by preventing the tip from hanging down and by ejecting a thick sheet or a strong sheet without going through the guide member. It is in.

[0008]

In order to achieve the above object, the sheet discharging mechanism of the present invention comprises a first sheet discharging roller downstream from the recording section in the sheet conveying direction, and is driven by being pressed against the sheet discharging roller. It has a rotating spur, a second paper discharge roller further downstream in the transport direction, and a spur that is pressed against and similarly driven by the paper discharge roller, and is discharged between the first paper discharge roller and the second paper discharge roller. It is placed near the width direction edge of the sheet to be printed,
A member that projects into the sheet transport path and guides the edge of the sheet upward from the sheet transport path. The first position that projects into the sheet transport path and guides the sheet edge upward and from the sheet transport path A first guide member that is movable in the retracted second position; a spring member that causes the first guide member to project into the sheet conveyance path by an elastic member such as a spring; The end portion of the sheet guided upward by the guide member is guided further upward between the first and second paper discharge rollers or in the same row as the second paper discharge roller, and the sheet is curved in a concave shape in the width direction. It is characterized in that it has a second guide member.

That is, the technical contents of the present invention can solve the above problems by providing the following constitutions.

(1) As a means for ejecting a sheet from the recording section, a first sheet discharge roller is provided downstream of the recording section in the sheet conveying direction, and a rotary member that is pressed against the sheet discharge roller and is driven to rotate.
Further, a second paper discharge roller is provided downstream in the conveying direction, and a rotary body that is pressed against the second paper discharge roller and is driven to rotate, and the sheet to be discharged is between the first paper discharge roller and the second paper discharge roller. A member that is disposed near the widthwise end portion of the sheet and that guides the end portion of the sheet upward from the sheet conveyance path, and that protrudes into the sheet conveyance path and that guides the sheet end portion upward; A first guide member movable between a second position retracted from the transport path and a first guide member downstream of the guide member in the transport direction, between the first and second paper discharge rollers or in substantially the same row as the second paper discharge roller. The sheet discharging mechanism further includes a second guide member that further guides the end portion of the sheet guided upward by the guide member upward and bends the sheet in a concave shape in the width direction.

(2) The first guide member is urged by an elastic means such as a spring from the second position retracted from the sheet conveying path toward the first position protruding into the sheet conveying path. The sheet discharge mechanism according to (1) above.

(3) As a means for ejecting a sheet from the recording section, a first sheet discharge roller is provided downstream of the recording section in the sheet conveying direction, and a rotary member which is pressed against the sheet discharge roller and is driven to rotate.
Further, a second paper discharge roller is provided downstream in the conveying direction, and a rotary body that is pressed against the second paper discharge roller and is driven to rotate, and the sheet to be discharged is between the first paper discharge roller and the second paper discharge roller. A first guide surface that is disposed in the vicinity of the width direction end portion of the sheet and that guides the end portion of the sheet upward from the sheet conveying path;
A second guide member that guides the end portion of the sheet guided upward by the first guide surface further upward in the conveying direction downstream of the guide surface and bends the sheet into a concave shape in the width direction. A sheet discharging mechanism, further comprising a guide member movable between a first position where the first guide surface projects into the sheet conveying path and a second position retracted from the sheet conveying path.

(4) The guide member is moved by an elastic means such as a spring from a second position where the first guide surface of the guide member is retracted from the sheet conveying path toward a first position where the first guide surface projects into the sheet conveying path. The sheet discharging mechanism according to (3) above, which is biased.

(5) In the above-mentioned (3), the guide member is provided with a gap through which the paper can pass in the height direction of the first guide surface and the second guide surface. Sheet discharge mechanism.

[0015]

DETAILED DESCRIPTION OF THE INVENTION

[0016]

[First Embodiment] An embodiment of a sheet discharging mechanism of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram of the overall configuration of an image forming apparatus according to an embodiment of the present invention, and FIGS. 2 to 5 are explanatory diagrams of a discharge mechanism section.

First, with reference to FIG. 1, the overall structure of the image forming apparatus of the present invention will be described from the upstream side in the conveying direction of the recording sheet S. A plurality of recording sheets S are stacked on the paper feed tray 1, and the uppermost one is separated and fed by the paper feed roller 2 driven and rotated by a drive unit (not shown) and the separation claw (not shown), and the conveyance unit The sheet S is conveyed to the recording position by the drive roller 3a which is driven and rotated, and the pinch roller 3b which presses the sheet S against the transport roller 3a and is driven to rotate.

The recording unit 4 discharges ink onto the sheet S conveyed by the conveying unit 3 by an ink jet recording system to perform recording, and includes a guide shaft 4a extending in the width direction of the recording sheet S and a guide rail 4b. A recording head 4d is mounted on a carriage 4c that can reciprocate along the carriage 4c. The recording head 4d is driven so as to be synchronized with the reciprocating motion of the carriage 4c, and ink drops are generated in accordance with an image signal by a platen 4e. Is ejected onto the sheet S on which is supported for recording. Further, the recording head 4d is integrated with an ink tank for storing ink on the upper part thereof, and the recording head 4d includes the carriage 4c.
It is detachably attached to.

Next, the sheet S recorded at the recording position
Is a sheet discharging means 5, 6, that is, a first discharging roller 5a which is driven to rotate, a spur 5b which is driven to rotate by pressing the sheet S against the first discharging roller 5a, and a second which is similarly driven to rotate.
The sheet is discharged onto the sheet discharge tray 7 by the sheet discharge roller 6a and the spur 6b.

Here, the spurs 5b and 6b refer to rotating bodies which have a small contact area with the sheet S and which do not disturb the ink image even when they come into contact with the ink in the unfixed state.

In the sheet S thus discharged onto the discharge tray 7 by the discharging means 5 and 6, when the rear end of the sheet is recorded, the portion supporting the sheet S is Although there are two rows of paper ejecting means 5 and 6, printing has already finished,
The leading edge of the sheet S discharged from the sheet discharging means 6, particularly plain paper having low rigidity, hangs down by its own weight, and is discharged while rubbing the ink image surface of the sheet S first discharged onto the sheet discharging tray 7. It is printed on paper and disturbs the image.

Therefore, in the embodiment of the present invention, the sheet S to be discharged is arranged near the widthwise end of the sheet S between the sheet discharging means 5 and 6 so that the leading edge of the sheet S does not hang down, and the sheet conveying path is provided. A first position for guiding the end portion of the sheet upward from the sheet conveying path with the guide member protruding inward;
A guide member 8 movable between a second position retracted from the sheet transport path, a spring member 9 that causes the guide member to project into the sheet transport path by an elastic member such as a spring, and a downstream side of the guide member in the transport direction. Then, the end portion of the sheet S guided upward by the guide member 8 is guided further upward between the first and second paper discharge rollers 5a and 6a or in substantially the same row as the second paper discharge roller 6a, By the second guide member 10 that bends the sheet in a concave shape in the width direction, the sheet S is provided with a waist so that the leading end does not hang down.
The sheet S is discharged and stacked without rubbing the image surface of the previously discharged sheet.

In the present embodiment, sheets of various sizes are supported, for example, A4 size and B5.
It corresponds to size, A5 size, official postcards, etc. Further, the sheet S is conveyed on the basis of one side with respect to the sheet conveying path of the image forming apparatus.
As shown in FIG. 3, the sheet is conveyed toward the sheet discharge port with the right end as a reference.

Next, the first and second guide members 8 and 10 described above will be described in detail. As shown in FIGS. 2 and 3, the first guide member 8 is located between the first paper discharge roller 5a and the second paper discharge roller 6a, and gradually increases from the upstream side to the downstream side in the sheet conveying direction. It has a wedge shape and is rotatably supported at the rotation center 8b at the upstream end. Also, in the width direction of the device,
2 near both ends of A4 size which is the maximum size of this device
They are arranged at various positions, and each of them is biased by a spring member 9 toward the side where the sheet S is lifted. The second guide member 10 is located downstream of the first guide member 8 in the transport direction and above the apex portion of the guide member 8 in the apparatus height direction with a space therebetween, and the first guide member 10 is provided. The guide surface 10a of the sheet S is provided downstream of the extension of the surface 8a that guides the sheet S in the sheet conveying direction.

The positional relationship between the first and second paper discharge rollers 5 and 6 will be described. The first discharge roller pair 5 is shown in FIG.
As shown in FIG. 3, the width of the second discharge roller pair 6 corresponds to the width of A4 size which is the maximum size of the apparatus.
As shown in FIG. 2 and FIG. 4, the left and right ends are arranged with a constant distance from the first and second guide members 8 and 9.

Here, taking a sheet having low rigidity, for example, A4 size plain paper Sp as an example, the first and second sheets at the time of discharging the sheet
The movements of the guide members 8 and 10 and the behavior of the plain paper Sp will be described with reference to FIGS. 2, 3, and 4. The plain paper Sp on which recording has been completed in the recording unit is conveyed by the first paper discharge roller pair 5, and the leading end of the plain paper Sp is guided by the guide surface 8a of the first guide member 8.
And the left and right ends thereof are lifted upward. At this time, the first guide member 8 is biased by the spring member 9, but since the plain paper Sp has low rigidity, it is held without changing its height. Therefore, both ends of the plain paper Sp are guided by the guide surface 10a of the second guide member 10, and the second paper discharge roller pair 6 keeps the plain paper Sp at the height of the sheet conveying path. It is possible to bend the plain paper Sp in a concave shape in the width direction to give the waist. Therefore, it is possible to discharge and stack the plain paper Sp without causing the leading end of the plain paper Sp to hang down and without rubbing the image surface of the previously discharged sheet.

Although the A4 size has been described here, when the size is smaller than the A4 size such as A5 and B5, as shown in FIG. 2, one of the guide members on the left and right in the device width direction has the reference side. Although only the guide member of will work, since the size is small, it is possible to give the seat a sufficient waist simply by lifting one end and bending it.
It is possible to obtain the same effect as A4 size plain paper.

Next, with reference to FIG. 5, when the rigid high sheet Sc (glossy paper, glossy film, OHP sheet, etc.) is used, the first and second guide members 8 and 10 at the time of discharging the sheet will be described. And the behavior of the highly rigid sheet Sc will be described. The plain paper Sp that has been recorded in the recording unit is the first
The sheet S is conveyed by the pair of sheet discharge rollers 5 and its tip comes into contact with the guide surface 8 a of the first guide member 8.
Since sheet c has a high rigidity, the spring member 9 urging the guide member 8 loses the rigidity of the sheet Sc and is pushed down to the second position retracted from the transport path. Therefore, both ends of the sheet Sc pass below the second guide member 10 and are not curved in a concave shape in the sheet width direction.
The paper is discharged by the paper discharge roller pair 6. At this time, in the case of a thick sheet or a stiff sheet, the rigidity of the sheet itself is high, and therefore the first sheet discharge roller pair 5 and the second sheet discharge roller pair 5 and the second sheet discharge sheet are not necessary even if the sheet is not curved. By supporting the two pairs of discharge rollers of the roller pair 6, the leading end of the sheet can be held without hanging down.

Moreover, since the height of the first guide member itself is set low, the conveyance resistance received by the sheet Sc from the first guide member 8 pushed down to the second position retracted from the conveyance path is sufficient. weak. Therefore, the conveyance accuracy is not disturbed, and the sheet end lifting force by the guide member does not reach the recording portion upstream of the first paper discharge roller.

[0030]

[Second Embodiment] FIG. 6 is an explanatory view of a discharge mechanism portion showing a second embodiment of the present invention. The same members as those in the first embodiment are designated by the same reference numerals, and a duplicate description will be omitted.
In the first embodiment, the first guide member 8 and the second guide member 10 are composed of different members, but in the second embodiment, as shown in FIG. 12 and is biased by a spring member 13 so as to project into the conveyance path. The guide surface 12a of the guide member plays the same role as the guide surface 8a of the first guide member 8 of the first embodiment, and the guide surface 12b of the second guide member 10 of the first embodiment.
Plays the same role as the guide surface 10a. Also guide surface 1
A portion 12d connecting the portions 2a and 12b is formed outside the maximum paper size which the recording apparatus is supposed to use in advance. Since the arrangement and the like are the same as those in the first embodiment, the description thereof will be omitted.

Here, taking a low-rigidity sheet, for example, A4 size plain paper Sp as an example, the movement of the guide member 12 and the behavior of the plain paper Sp when the paper is discharged will be described with reference to FIGS. 3 and 5. . The plain paper Sp on which recording has been completed in the recording unit is conveyed by the first paper discharge roller pair 5, its leading end is guided by the guide surface 12a of the guide member 12, and its left and right ends are lifted upward. At this time, the guide member 12 is biased by the spring member 13, but since the plain paper Sp has low rigidity, it is held without changing the first height shown in FIG. Therefore, both ends of the plain paper Sp are further guided by the guide surfaces 12b, and the second paper discharge roller pair 6 keeps the plain paper Sp at the height of the sheet conveying path, so that the plain paper Sp is width-wise. It becomes possible to give a waist by curving into a concave shape. Therefore, it is possible to discharge and stack the plain paper Sp without causing the leading end of the plain paper Sp to hang down and without rubbing the image surface of the previously discharged sheet.

Although the A4 size has been described here, when the size is smaller than the A4 size such as A5 and B5, as shown in FIG. 2, one of the guide members on the left and right in the device width direction has the reference side. Although only the guide member of will work, since the size is small, it is possible to give the seat a sufficient waist simply by lifting one end and bending it.
It is possible to obtain the same effect as A4 size plain paper.

Next, with reference to FIG. 7, in the case where a sheet Sc having high rigidity (glossy paper, glossy film, OHP sheet, etc.) is used, the movement of the guide member 12 at the time of discharging the sheet, and the sheet having a strong stiffness The behavior of Sc will be described. The plain paper Sp on which recording has been completed in the recording unit is the first paper discharge roller pair 5
Is conveyed, and its leading end abuts on the guide surface 12a of the guide member 12. Here, since the sheet Sc has a high rigidity, the spring member 1 urging the guide member 12 is urged.
3 loses the rigidity of the sheet Sc, and the guide surface 12a is pushed down to the second position retracted from the transport path. After that, the front end of the sheet Sc passes through the gap 12c formed between the guide surfaces 12a and 12b, and is discharged by the second paper discharge roller pair 6 without being curved concavely in the sheet width direction. At this time, since the sheet itself has a high rigidity, the sheet is supported by two rows of the first sheet discharge roller pair 5 and the second sheet discharge roller pair 6 even if the sheet is not curved. By doing so, the seat can be held without hanging down.

Moreover, since the height of the guide surface 12a itself is set low, the conveyance resistance received by the sheet from the guide surface 12a pushed down to the second position retracted from the conveyance path is also sufficiently weak. Therefore, there are irregularities in conveyance accuracy,
The lifting force of the sheet end portion by the guide member does not spread to the recording portion upstream of the first row sheet ejection rollers.

[0035]

According to the sheet discharging mechanism of the present invention, a first sheet discharging roller is provided downstream of the recording section in the sheet conveying direction, a spur which is pressed against the sheet discharging roller and is driven to rotate, and a second sheet discharging roller is further provided downstream in the sheet conveying direction. A discharge roller and a spur that is pressed against the discharge roller and is driven to rotate are also provided. The first discharge roller and the second discharge roller are provided.
A first guide member arranged between the discharge rollers near the width direction of the discharged sheet and configured to guide the end portion of the sheet upward from the sheet conveyance path by a guide member protruding into the sheet conveyance path.
Position, a first guide member movable to a second position retracted from the sheet conveying path, a spring member that causes the guide member to project into the sheet conveying path by an elastic member such as a spring, and the guide member. At the downstream side in the conveying direction, the end portion of the sheet guided upward by the guide member is guided further upward between the first and second sheet discharging rollers or in substantially the same row as the second sheet discharging roller, and the sheet width is increased. By having a second guide member that bends in a concave shape in the direction, it is possible to lift the edge of the sheet and impart a concave curvature to the sheet in the case of a weak sheet, so the sheet to be discharged It is possible to prevent the leading edge of the sheet from hanging down and rubbing the unfixed ink on the previously discharged sheet.

Further, in the case of a sheet such as a thick paper, since the rigidity of the sheet itself is strong, the spring member urging the first guide member loses the rigidity of the sheet, and the first guide member is conveyed by the conveying path. It is pushed down to the second position where it retracts from.
Therefore, the sheet is discharged horizontally, and the height itself of the first guide member is set low, so that the sheet is conveyed by the first guide member pushed down to the second position retracted from the conveying path. Because the resistance is weak enough,
The conveyance accuracy is not disturbed, and the sheet edge lifting force by the guide member does not reach the recording portion upstream of the first-row sheet discharge rollers.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a perspective view of a paper discharge mechanism unit according to the first embodiment of the present invention.

FIG. 3 is a side view of a paper discharge mechanism unit according to the first embodiment of the present invention when a sheet having low rigidity is conveyed.

FIG. 4 is a front view of a paper discharge mechanism unit according to the first embodiment of the present invention when a highly rigid sheet is conveyed.

FIG. 5 is a side view of a paper discharge mechanism unit in the first embodiment of the present invention when a highly rigid sheet is conveyed.

FIG. 6 is a perspective view of a paper discharge mechanism section according to the second embodiment of the present invention.

FIG. 7 is a side view of a paper discharge mechanism unit according to the second embodiment of the present invention when a highly rigid sheet is conveyed.

FIG. 8 is an overall configuration diagram of a conventional example

FIG. 9 is a perspective view of a paper discharge mechanism in a conventional example.

FIG. 10 is a side view of a paper discharge mechanism unit in a conventional example when a highly rigid sheet is conveyed.

[Explanation of symbols]

1 Paper tray 2 paper feed rollers 3 transportation means 5 First paper discharging means 6 Second paper ejection means 7 Output tray 8 First guide member 10 Second guide member 12 Guide member

Claims (5)

[Claims] 1. As a means for ejecting a sheet from a recording section, a first sheet discharge roller is provided downstream of the recording section in the sheet conveying direction, and a rotating body which is pressed against the sheet discharge roller and is driven to rotate.
Further, a second paper discharge roller is provided downstream in the conveying direction, and a rotary body that is pressed against the second paper discharge roller and is driven to rotate, and the sheet to be discharged is between the first paper discharge roller and the second paper discharge roller. A member that is disposed near the widthwise end portion of the sheet and that guides the end portion of the sheet upward from the sheet conveyance path, and that protrudes into the sheet conveyance path and that guides the sheet end portion upward; A first guide member movable between a second position retracted from the transport path and a first guide member downstream of the guide member in the transport direction, between the first and second paper discharge rollers or in substantially the same row as the second paper discharge roller. The sheet discharging mechanism further includes a second guide member that further guides the end portion of the sheet guided upward by the guide member upward and bends the sheet in a concave shape in the width direction. 2. The first guide member is urged by an elastic means such as a spring from a second position retracted from the sheet conveying path toward a first position protruding into the sheet conveying path. The sheet ejection mechanism according to claim 1, wherein: 3. As a means for discharging a sheet from a recording section, a first sheet discharge roller is provided downstream of the recording section in the sheet conveying direction, and a rotating body that is pressed against the sheet discharge roller and is driven to rotate.
Further, a second paper discharge roller is provided downstream in the conveying direction, and a rotary body that is pressed against the second paper discharge roller and is driven to rotate, and the sheet to be discharged is between the first paper discharge roller and the second paper discharge roller. A first guide surface that is disposed in the vicinity of the width direction end portion of the sheet and that guides the end portion of the sheet upward from the sheet conveying path;
A second guide member that guides the end portion of the sheet guided upward by the first guide surface further upward in the conveying direction downstream of the guide surface and bends the sheet into a concave shape in the width direction. A sheet discharging mechanism, further comprising a guide member movable between a first position where the first guide surface projects into the sheet conveying path and a second position retracted from the sheet conveying path. 4. The guide member is attached by an elastic means such as a spring from a second position where the first guide surface of the guide member is retracted from the sheet conveying path to a first position direction where it projects into the sheet conveying path. The sheet ejection mechanism according to claim 3, wherein the sheet ejection mechanism is biased. 5. The guide member according to claim 3, wherein a gap through which paper can pass is provided in a height direction of the first guide surface and the second guide surface of the guide member. Sheet ejection mechanism.