JP4578726B2 - Image forming machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming machine such as an electrostatic printing machine (printer), a copying machine, or a facsimile machine.
[0002]
[Prior art]
In an image forming machine such as an electrostatic printer, a copying machine, or a facsimile, when a sheet member, which may be plain paper, is transported through a predetermined transport path in a housing, a toner image is transferred onto the sheet member, and then The toner image is fixed on the sheet member, thus forming an image on the sheet member. In many cases, images are formed not only on one side of a sheet member but also on both sides. The image forming machine is provided with a receiving unit together with a discharging unit, and a sheet member on which an image is formed on at least one side is discharged from the housing by the discharging unit and placed on the receiving unit. Usually, the discharge means is composed of a discharge roller pair, and the sheet member is discharged in a tangential direction at the nip portion of the discharge roller pair. The receiving means has a mounting surface that extends below the discharge path of the sheet member, and hence the tangent at the nip portion of the discharge roller pair.
[0003]
When a large number of sheet members are stacked on the mounting surface of the receiving means, the thickness of the sheet member layer increases, and the upper surface of the sheet member layer is near the nip portion of the discharge roller pair, the discharge roller pair For example, the discharged sheet member may collide with the sheet member layer on the receiving means or may enter between the sheet member layers, and the discharge as required may be damaged. Therefore, a full load detecting means for detecting when the thickness of the sheet member layer placed on the receiving means exceeds a predetermined value is also provided. A typical example of such full load detection means is a swivel that extends upstream of the nip portion of the discharge roller pair and above the nip portion of the discharge roller pair in parallel with the central axis of the discharge roller pair as viewed in the discharge direction of the sheet member. It has a detection arm mounted so as to be rotatable about an axis. The detection arm is pivotable between the lowest position and the highest position, and is biased to the lowest position by its own weight or by the action of an appropriate biasing means. In the lowest position, the detection end of the detection arm is positioned below the upper surface of the sheet member layer when the thickness of the sheet member layer placed on the placement surface of the receiving means reaches the predetermined value. To do. When the sheet member is discharged by the action of the discharge roller pair, the sheet member comes into contact with the detection arm and pivots it upward from the discharge path. When the sheet member passes the detection arm, the detection arm is at the lowest position. It is made to move toward recovery. When the thickness of the sheet member layer on the mounting surface of the receiving means reaches the predetermined value, the detection end of the detection arm is slightly above the lowest position even if the discharged sheet material passes through the detection arm. Accordingly, it is detected that the layer thickness of the sheet member layer has reached the predetermined value, that is, that the sheet member is fully loaded on the mounting surface of the receiving means. When it is detected that the sheet member is full, the discharge of the sheet member from the housing is prohibited.
[0004]
[Problems to be solved by the invention]
In the image forming machine of the above-described form, as is well known to those skilled in the art, one side of the sheet member is heated when the toner image is fixed on the sheet member, or the sheet member is conveyed through a curved conveyance path. For example, the sheet member discharged from the housing is often curled. When the sheet member is curled upward, that is, its front edge is curled upward, the discharged sheet member tends not to be placed on the placement surface of the receiving means as required. Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-11765, in the conventional image forming machine, the curl correction for correcting the curling of the sheet member upstream of the discharge roller pair as viewed in the discharge direction of the sheet member. Means were arranged. However, such a curl correcting means is considerably complicated and bulky, thus increasing the manufacturing cost of the image forming machine and hindering the downsizing of the image forming machine.
[0005]
The present invention has been made in view of the above-mentioned facts, and its main technical problem is to improve the image forming machine of the above-described form from the housing without significantly increasing the manufacturing cost and increasing the bulk. In the case where the sheet member to be discharged is curled upward, the curling can be appropriately corrected.
[0006]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors limit the uppermost position of the detection arm of the full load detection means so that even when the detection arm is brought to the uppermost position, at least a part of the detection arm interferes with the discharge path of the sheet member. When the sheet member is curled upward, the main technical problem can be achieved by correcting the upward curl by acting on the sheet member to which the detection arm is discharged. I found out that I can do it.
[0007]
That is, according to the present invention, as an image forming machine that achieves the main technical problem, a housing, a discharge means for discharging a sheet member having an image formed on at least one side from the housing, and the discharge means A receiving means for receiving the sheet member discharged from the housing; and a full load detecting means for detecting when the thickness of the sheet member layer placed on the receiving means exceeds a predetermined value. Has a mounting surface extending below the discharge path of the sheet member discharged from the discharge means, and the full load detection means is an image forming machine having a detection arm.
The detection arm of the full load detecting means is movable between a lowermost position and an uppermost position, and when the detection arm is positioned at the lowermost position, the detection end of the detection arm is placed on the mounting surface. Even when the thickness of the placed sheet member layer reaches the predetermined value, it is positioned below the upper surface of the sheet member layer and the detection arm is positioned at the uppermost position. There is provided an image forming machine characterized in that at least a part of the sheet member interferes with a discharge path of the sheet member, and the detection arm has a curl correcting function for the sheet member discharged by the discharge means.
[0008]
In a preferred embodiment, the discharge means comprises a pair of discharge rollers, and the discharge path of the sheet member extends in a tangential direction at the nip portion of the pair of discharge rollers. The detection arm of the full load detection means is mounted so as to be rotatable about a turning axis extending parallel to the central axis direction of the discharge roller pair on the upstream side of the discharge roller pair as viewed in the discharge direction of the sheet member. At least the distal end portion of the detection arm extends while being inclined downward toward the downstream in the discharge direction of the sheet member at both the lowermost position and the uppermost position.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS A preferred embodiment of an image forming machine configured according to the invention will be described below with reference to the accompanying drawings.
[0010]
Referring to FIGS. 1 and 2, a preferred embodiment of an image forming machine configured according to the present invention has a housing 2 having a substantially rectangular parallelepiped shape as a whole. On the upper surface of the housing 2, in the central region excluding both sides in the width direction (direction perpendicular to the paper surface in FIG. 2), the upper wall extends substantially horizontally from the front edge to the substantially middle portion in the front-rear direction, and then the rear end A mounting surface 4 is formed extending slightly inclined downward toward the part. The mounting surface 4 constitutes a receiving means for receiving the sheet member discharged from the housing 2. An upright wall 6 extending substantially vertically upward from the rear end of the mounting surface 4 is also disposed on the upper surface of the housing 2, and a discharge port 8 extending in the width direction is formed in the upright wall 6. ing. Discharge means comprising four discharge roller pairs 10 is disposed at the discharge port 8. More specifically, a rotating shaft 12 extending in the width direction is rotatably mounted in the housing 2 adjacent to the discharge port 8, and four such rotating shafts 12 are appropriately spaced in the width direction. The driving roller 14 is fixed. Further, a short shaft (not shown) extending in the width direction corresponding to each of the four drive rollers 14 is fixed in the housing 2, and the driven roller 16 of each of the short shafts is freely rotatable. It is attached to. The rotating shaft 12 is connected to an electric motor (not shown), and when the rotating shaft 12 is rotationally driven in the direction indicated by the arrow 18 by the electric motor, the driving roller 14 is driven and the driven roller 16 is driven. .
[0011]
Although not shown, a plurality of sheet members, which may be plain paper, are accommodated in the housing 2 in a stacked state, and each of the sheet members is conveyed through a conveyance path defined in the housing 2. The toner image is transferred and fixed on at least one side of the sheet member. Then, the sheet member having the fixed toner image is conveyed to the discharge roller pair 10 constituting the discharge means, and discharged onto the placement surface 4 through the discharge opening 8 by the action of the discharge roller pair 10. As shown by a two-dot chain line arrow 20 in FIG. 2, the discharge roller pair 10 sends the sheet member in the tangential direction of the driving roller 14 and the driven roller 16 at the nip portion between the driving roller 14 and the driven roller 16. Accordingly, the mounting surface 4 constituting the receiving means extends below the discharge path of the sheet member.
[0012]
As understood by referring to FIG. 2, the sheet member discharged from the discharge port 8 is received and stacked on the mounting surface 4, but the layer thickness of the sheet member layer on the mounting surface 4 Is excessively large, the sheet member newly discharged from the discharge port 8 may collide with the sheet member layer on the mounting surface 4 or may enter between the sheet members. Therefore, a full load detecting means 22 is provided for detecting when the thickness of the sheet member layer on the mounting surface 4 exceeds a predetermined value and stopping the operation of the image forming machine. Continuing with reference to FIG. 3 in conjunction with FIGS. 1 and 2, the full load detection means 22 in the illustrated embodiment includes a detection member 24 that is conveniently molded integrally from a suitable synthetic resin. Yes. The detection member 24 has a shaft portion 26 extending in the width direction. A detection arm 28 is formed at the center of the shaft portion 26. The detection arm 28 has a proximal end portion 30 and a distal end portion 32 bent downward at an angle of about 30 degrees with respect to the proximal end portion 30. A detection protrusion 33 protruding upward is formed on the upper surface of the base end portion 30. A projecting piece 34 is formed at one end of the shaft portion 26 so as to project in the discharge direction of the sheet member. Such a detection member 24 is rotatably mounted so that the shaft portion 26 extends in the housing 2 along the discharge port 8. As clearly shown in FIG. 2, the shaft 26 advantageously extends upstream of the discharge roller pair 10 and somewhat above the nip portion of the discharge roller pair 10.
[0013]
It is important that the detection member 24 constituting the full load detection means 22 is rotatably mounted between a lowermost position indicated by a solid line in FIG. 2 and an uppermost position indicated by a two-dot chain line 24A in FIG. When the detection member 24 reaches the lowermost position shown by a solid line in FIG. 2, the lower surface of the base end portion 30 of the detection arm 28 is conveyed to the guide wall 35 (the discharge port 8) extending in the housing 2 toward the discharge port 8. 2 is prevented from further rotating in the counterclockwise direction in FIG. 2 beyond the lowermost position. On the other hand, when the detection member 24 reaches the uppermost position indicated by a two-dot chain line 24A in FIG. 2, the upper edge of the protruding piece 34 formed at one end of the shaft portion 26 as shown by the two-dot chain line in FIG. The detection member 24 is prevented from further rotating in the clockwise direction in FIG. 2 beyond the uppermost position by coming into contact with the lower end of the rib 38 that hangs downward from the upper surface wall on one side. The detection member 24 is biased to the lowest position shown by a solid line in FIG. 2 when the sheet member does not act on the detection arm 28 due to its own center of gravity. If desired, an appropriate spring member that elastically biases the detection member 28 to the lowest position can be provided.
[0014]
When the detection member 24 is positioned at the lowest position, the detection arm 28 has a base end portion 30 that protrudes substantially horizontally beyond the nip portion of the discharge roller pair 10 and a tip end portion 32 thereof. It extends downward beyond the discharge path of the sheet member discharged by the discharge roller pair 10, that is, the discharge path indicated by a two-dot chain line arrow 20 in FIG. 2.
The detection end 40 of the detection arm 28 has an upper surface (indicated by a two-dot chain line 36 in FIG. 2) when the layer thickness of the sheet member received on the mounting surface 4 reaches a predetermined value, that is, a full load detection value. It is important to be positioned below the plane shown). On the other hand, when the detection member 24 is positioned at the uppermost position 24A, the detection arm 28 has its base end portion 30 extending obliquely upwardly toward the downstream in the sheet discharging direction, and its distal end portion 32. Extends downwardly in the discharge direction of the sheet member. In the image forming machine configured according to the present invention, it is important that at least a part of the detection arm 28 interferes with the discharge path indicated by the two-dot chain line arrow 20 even when the detection member 24 is brought to the uppermost position. . In the illustrated embodiment, even if the detection member 24 is brought to the uppermost position, the distal end portion 32 of the detection arm 28 extends downward beyond the discharge path indicated by the two-dot chain line arrow 20, and the distal end portion 32 of the detection arm 28. Interferes with the discharge path indicated by the two-dot chain line arrow 20.
[0015]
The operation of the full load detecting means 22 as described above will be summarized. When the number of sheet members mounted on the mounting surface 4 is sufficiently small, the detection is performed when the sheet members are not discharged through the discharge port 8. The member 24 is positioned at the lowest position indicated by a solid line in FIG. 2, and the upper surface of the sheet member layer on the mounting surface 4 is positioned below the detection end 40 of the detection arm 28. When the sheet member is discharged through the discharge port 8, the sheet member acts on the distal end portion 32 of the detection arm 28, whereby the detection member 24 is rotated to the uppermost position indicated by a two-dot chain line 24A in FIG. When the detection member 24 is rotated to the uppermost position, as described above, the lower edge of the rib 38 where the upper edge of the protruding piece 34 formed at one end of the shaft portion 26 hangs downward from the upper surface wall at one side portion of the housing 2. 2 and the detection member 24 is prevented from further rotating in the clockwise direction in FIG. 2 beyond the uppermost position. Even when the detection member 24 is rotated to the uppermost position, the distal end portion 32 of the detection arm 28 continues to interfere with the discharge path indicated by the two-dot chain line arrow 20. Therefore, as shown by a two-dot chain line 42 in FIG. 2, when the discharged sheet member is curled upward, that is, its front edge is curled upward, the sheet is caused by the interference of the tip 32 of the detection arm 28. The member is forced downward, and the curling of the sheet member is corrected. On the other hand, in the case of a highly rigid sheet member that does not easily curl, the detection end 40, which is the tip of the detection arm 28, can hardly correct the sheet member downward, and is close to the discharge path indicated by the two-dot chain line 20. Although the detection member 24 tends to be displaced upward, the detection member 24 is damaged due to deformation caused by twisting about the shaft portion 26 by molding the detection member 24 from a synthetic resin that can be elastically deformed relatively easily. This can be avoided sufficiently reliably.
[0016]
When a considerable number of sheet members are received on the mounting surface 4 and the upper surface of the sheet member layer is above the detection end 40 of the detection arm 28 at the lowest position, the detection member 28 is counterclockwise in FIG. Is prevented by the sheet member layer. Then, when the thickness of the sheet member layer on the mounting surface 4 reaches a predetermined value, that is, the full load detection value, and the upper surface of the sheet member layer reaches the position indicated by a two-dot chain line 36 in FIG. Even when the sheet member is not discharged through the outlet 8, it does not fall below the position indicated by the two-dot chain line 24B in FIG. 2 (rotated counterclockwise in FIG. 2). In the housing 2, a micro switch for detecting a detected protrusion 33 protruding upward from the base end portion 30 of the detection arm 28 only when the detection arm 28 is positioned below the two-dot chain line 24 b in FIG. 2. A detector (not shown) that can be constructed from is provided. Therefore, when the thickness of the sheet member layer on the mounting surface 4 is equal to or smaller than the predetermined value, the detector detects the detected protrusion 33 after the discharge of the sheet member is completed. When the thickness of the sheet member layer exceeds a predetermined value, the detector does not detect the detected protrusion 33 even when the discharge of the sheet member is completed. In this case, the operation of the image forming machine is prohibited, and warning means (not shown) such as a warning lamp or a warning buzzer for warning the operator that the sheet member is fully loaded on the mounting surface 4 ) Is activated.
[0017]
【The invention's effect】
In the image forming machine configured in accordance with the present invention, a part of the detection arm of the full load detection means interferes with the sheet member to exhibit the curl correction function, and therefore involves a considerable increase in manufacturing cost and an increase in bulk. If the sheet member discharged from the housing is curled upward, the curl can be corrected appropriately.
[Brief description of the drawings]
FIG. 1 is a simplified perspective view showing an upper half of an image forming machine configured according to the present invention.
2 is a partial cross-sectional view showing the vicinity of a discharge port of a sheet member in the image forming machine of FIG.
3 is a perspective view showing a detection member constituting full load detection means in the image forming machine of FIG. 1;
[Explanation of symbols]
2: Housing 4: Mounting surface (receiving means)
8: Discharge port 10: Discharge roller pair (discharge means)
20: Sheet member discharge path 22: Full load detection means 24: Detection member 28: Detection arm

Claims (3)

A housing, a discharging means for discharging the sheet member having an image formed on at least one side thereof from the housing, a receiving means for receiving the sheet member discharged from the housing by the discharging means, and mounted on the receiving means; A full load detecting means for detecting when the thickness of the sheet member layer exceeds a predetermined value, and the receiving means is mounted under the discharge path of the sheet member discharged from the discharge means In an image forming machine having a surface and the full load detection means has a detection arm,
The detection arm of the full load detecting means is movable between a lowermost position and an uppermost position, and when the detection arm is positioned at the lowermost position, the detection end of the detection arm is placed on the mounting surface. Even when the thickness of the placed sheet member layer reaches the predetermined value, it is positioned below the upper surface of the sheet member layer and the detection arm is positioned at the uppermost position. An image forming machine, wherein at least a part of the sheet member interferes with a discharge path of the sheet member, and the detection arm has a curl correction function for the sheet member discharged by the discharge unit. The image forming apparatus according to claim 1, wherein the discharge unit includes a pair of discharge rollers, and the discharge path of the sheet member extends in a tangential direction at a nip portion of the pair of discharge rollers. The detection arm of the full load detection means is mounted so as to be rotatable about a turning axis extending parallel to the central axis direction of the discharge roller pair on the upstream side of the discharge roller pair as viewed in the discharge direction of the sheet member. 3. The image forming machine according to claim 2, wherein at least a front end portion of the detection arm extends while being inclined downward toward the downstream side in the discharge direction of the sheet member at both the lowermost position and the uppermost position.

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