JP2005263389A - Paper feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, holding back a lift base plate in a proper height position for picking up paper. <P>SOLUTION: In this paper feeder, in order to prevent the lift base plate from being lifted more than needed by vibration of a support frame after the movement of paper to the proper height position for picking up, it is determined whether or not the rising angle of the lift elevating plate is varied according to whether or not the paper is located in the proper height position, and the current rising angle of the lift elevating plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a paper feeding device that feeds an image forming apparatus such as a printer, a copying machine, or a multifunction peripheral.

  The paper feeding device of the image forming apparatus is configured to be able to transport sheets one by one to a transfer unit formed by a photosensitive drum, a transfer roller, or the like when requested by the image forming apparatus. As shown in FIG. 5, the paper feeding device 100 is housed in the paper feeding cassette 110, the storage sensor 107 that detects whether or not the paper feeding cassette 110 is stored in the image forming apparatus, and the paper feeding cassette 110. A paper feed mechanism that enables the fed paper to be fed.

  The sheet feeding mechanism includes a pickup roller 104, a position detecting unit 111 that detects whether or not the sheet stored in the sheet feeding cassette 110 is positioned at an appropriate height position suitable for the pickup of the pickup roller 104, and the appropriateness A lift motor 105 that moves the paper to a height position, a rotary shaft 103 that transmits the rotational force of the lift motor 105, and an angle changing unit 113 that controls the lift motor 105 are provided.

  The sheet feeding cassette 110 is fixed at one end to the lift bottom plate 101 on which the sheet bundle S is placed and the rotating shaft 103 that rotates in conjunction with the lift motor 105, and the rising angle changes when the rotating shaft 103 rotates. A lift elevating plate 102 that pushes the lift bottom plate 101 toward the pickup roller 104 at the other end is provided.

  The rotary shaft 103 and the motor shaft of the lift motor 105 are configured to mesh with each other when the paper feed cassette 110 is stored in the image forming apparatus. Therefore, only when the paper feed cassette 110 is housed in the image forming apparatus, the rotational force of the lift motor 105 is transmitted to the rotary shaft 103, and the paper feed cassette 110 is external to the image forming apparatus for replenishing paper. When it is pulled out, the rotational force of the lift motor 105 is not transmitted to the rotating shaft 103. Therefore, when the paper feed cassette 110 is pulled out, the rotary shaft 103 and the lift motor 105 are not engaged with each other, so that the lift elevating plate 102 is fed by the weight of the lift bottom plate 101 and the paper bundle S. Has fallen to the bottom.

  When the storage cassette 107 detects that the paper feed cassette 110 is housed in the image forming apparatus from a state in which the paper feed cassette 110 is pulled out by a user or the like, the angle changing unit 113 The lift bottom plate 101 is pushed up by driving 105 to increase the rising angle of the lift lifting plate 102. When the sheet bundle S reaches the appropriate height position where the pickup roller 104 is pushed up with an appropriate force by this pushing up, the position detecting means 111 detects that the sheet has been raised to the appropriate height position.

  For example, as described in Japanese Patent Application Laid-Open No. 9-110188, detection of whether or not the sheet has risen to an appropriate height position is performed by using a transmission type optical sensor 210 shown in FIG. This is performed depending on whether or not the front end portion 212 of 211 has shielded the optical path of the optical sensor 210. Hereinafter, the distal end portion 212 is referred to as a light shielding portion 212.

  The support frame 211 is rotatably attached to the housing 213 of the image forming apparatus. As described above, when the lift bottom plate 101 is pushed up, the pickup roller 104 is pushed up from below by the sheet bundle S placed on the lift bottom plate 101, and the support frame 211 has the housing 213 as the center of rotation. Rotate upward in FIG. When the support frame 211 rotates by a predetermined angle, the light shielding part 212 is positioned at a position where the light emitted from the optical sensor 210 can be shielded.

  When the light emitted from the optical sensor 210 is blocked, the position detection unit 111 detects that the paper has been raised to an appropriate height position. When the position detecting unit 111 detects that the sheet has been raised to an appropriate height position, the angle changing unit 113 stops the lift motor 105.

When the sheet is transported to the transfer unit and the sheet bundle S becomes thin, the amount of pushing up the sheet bundle S with respect to the pickup roller 104 becomes small. Therefore, when a certain number of sheets are fed, the light emitted from the optical sensor 210 is emitted. The light shielding unit 212 is not shielded from light. When the light is no longer blocked, the position detection unit 111 detects that the sheet is not positioned at the proper height position. When it is detected that the sheet is not positioned at the appropriate height position, the angle changing unit 113 detects the lift bottom plate until the detecting unit 111 detects again that the sheet has been raised to the appropriate height position. 101 is raised.
JP-A-9-110188

  As described above, since the support frame 211 that supports the pickup roller 104 is rotatably attached to the image forming apparatus, when the image forming apparatus vibrates or is picked up by the pickup roller 104 by an external force. When the sheet is bent and the force to return the sheet to the original state is transmitted to the support frame 211 via the pickup roller 104, the support frame 211 may rotate upward. If the support frame 211 rotates upward when the light shielding unit 212 is positioned to shield the light emitted from the optical sensor 210, the light emitted from the optical sensor 210 is not shielded.

  As described above, when the light is no longer blocked, the position detecting unit 111 detects that the sheet is not positioned at an appropriate height, and the angle changing unit 113 raises the lift bottom plate 101. When the reason why the light is not blocked is not the paper feed but the rotation of the support frame 211 due to the vibration of the image forming apparatus or the like, when the lift bottom plate 101 is pushed up, the paper moves above the appropriate height position, The pick-up roller 104 is pushed up with a force more than necessary, and the paper pick-up is not normally performed. Further, when the sheet bundle S moves upward from the proper height position, when the sheet feeding cassette 100 is pulled out, the lift bottom plate 101 and the sheet bundle S are caught by the housing of the image forming apparatus, and the sheet feeding cassette 100 cannot be pulled out. Sometimes things happen.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of restraining a lift bottom plate at an appropriate height position of a paper pickup.

  In the paper feeding device of the present invention, after the paper moves to the proper height position of the pickup, the paper is positioned at the proper height position in order to prevent the lift bottom plate from rising more than necessary due to the vibration of the support frame. It is determined whether or not the rising angle of the lift lifting plate is to be changed based on whether or not the lift lift plate is lifted.

  Since one end of the lift lifting plate is fixed to the lift roller 103 and fixed to the shaft of the lift motor 105, the lift roller 103 does not move easily unless the lift motor 105 rotates. The lift lifting plate hardly vibrates even if the image forming apparatus vibrates or a force that causes the bent sheet to return to the original state is generated because the weight is pressed down. Therefore, the rising angle of the lift lifting plate is hardly affected by the vibration of the image forming apparatus and the force that the bent sheet tries to return to the original state.

  The rising angle of the lift elevating plate when the sheet is positioned at the proper height position can be predicted in advance from the positional relationship among the pickup roller, the lift bottom plate, and the lift elevating plate. Therefore, even if it is detected that the paper is not positioned at the appropriate height position, when the current rising angle of the lift lift plate is an angle at which it can be predicted that the paper is positioned at the appropriate height position, It can be determined that the paper is no longer positioned at the appropriate height position due to the vibration. In this case, the paper feeder does not change the rising angle of the lift lifting plate.

  Since the vibration of the support frame is settled after a certain period of time, if it is detected that the sheet is not positioned at the appropriate height for a certain period of time, the sheet bundle is thinned because the sheet is conveyed to the transfer unit. It can be determined that the sheet is no longer positioned at the proper height position. Accordingly, when such a state continues for a certain period of time, the sheet feeding device increases the rising angle of the lift lifting plate.

  In the paper feeding device of the present invention, the image forming apparatus vibrates due to whether or not the paper is positioned at an appropriate height position, and a force to return the bent paper to its original state is generated. However, the rising angle of the lift lifting plate is changed based on the rising angle of the lift lifting plate that hardly vibrates. For this reason, it is possible to prevent the sheet from moving upward from the appropriate height position, so that it is possible to prevent a situation in which the pickup is not normally performed or the sheet feeding cassette cannot be pulled out.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a paper feeding device 100 according to the present invention. Components common to the conventional paper feeding device will be described with the same reference numerals as those used in the background art.

  As shown in FIG. 1, the paper feeding device 100 is the same as the conventional paper feeding device 100 shown in FIG. 5, and whether or not the paper feeding cassette 110 and the paper feeding cassette 110 are stored in the image forming apparatus. A storage sensor 107 to detect, and a paper feed mechanism that enables the paper stored in the paper feed cassette 110 to be fed.

  The sheet feeder 100 of the present invention includes an angle detection unit 112 that detects the rising angle of the lift lifting plate 102 that the conventional sheet feeder 100 does not have. The angle changing unit 113 changes the rising angle of the lift elevating plate 102 based on whether the sheet feeding operation is being performed and the detection results of the position detecting unit 111 and the angle detecting unit 112.

  When the sheet feeding cassette 110 pulled out is stored in the image forming apparatus by a user or the like and this storage is detected by the storage sensor 107, the angle changing unit 113 detects the detection result of the position detecting unit 111. Is recognized (FIG. 2, S201 → S202). The angle changing unit 113 does not drive the lift motor 105 regardless of the detection result of the angle detecting unit 112 when the position detecting unit 111 detects that the sheet is rising to an appropriate height position. (FIG. 2, S202 → S203).

  As described in the background art, when the paper feed cassette 110 is pulled out, the lift elevating plate 102 is in a state of falling to the bottom of the paper feed cassette 110, so that the paper feed cassette is accommodated. At this point, the paper is not positioned at the proper height. Therefore, immediately after the storage of the paper cassette 110 is detected by the storage sensor 107, the angle changing unit 113 lifts until the position detection unit 111 detects that the sheet is positioned at the appropriate height position. The lift 105 is raised by driving the motor 105 (FIG. 2, S202 → S204).

  The angle changing unit 113 raises the lift bottom plate 101 until the position detecting unit 111 detects that the sheet has been raised to an appropriate height position, so that the sheet is picked up normally. Based on the detection result of the position detector 111, it is monitored whether or not the sheet is positioned at an appropriate height position. Once it is detected that the paper has been raised to the appropriate height position, if the position detecting means 111 detects that the paper is not located at the appropriate height position (FIG. 2, S205 NO), the angle change is performed. The means 113 acquires the detection result of the angle changing means 112 if the paper feeding operation is not in progress (NO in S206 in FIG. 2). The angle changing unit 113 determines whether or not the acquired detection result is the rising angle of the lift lifting plate 102 when the sheet is positioned at an appropriate height (S207 in FIG. 2).

  In the present embodiment, the rising angle of the angle detecting means 112 is detected using a lift lifting plate 102 having a hole in the center as shown in FIG. 4 and an optical sensor 301 that emits light in the horizontal direction. it can. The angle during the sheet feeding operation of the lift lifting plate 102 is as shown in FIG. 3A when the maximum thickness sheet bundle S on which the lift bottom plate 101 can be placed is placed on the lift bottom plate 101. The rising angle (hereinafter referred to as “minimum rising angle”) of the lift lifting plate 102 when the uppermost sheet of the sheet bundle S is positioned at the appropriate height position, and the sheet as shown in FIG. When the bundle S is not placed, the lift roller 104 is pushed up by the lift bottom plate 101 so that the light of the optical sensor 210 is blocked by the light blocking portion 212 (hereinafter referred to as “maximum”). It is an angle between “rise angle”. When the rising angle of the lift lifting plate 102 is an angle between the maximum rising angle and the minimum rising angle, the light from the optical sensor 301 is transmitted through the hole opened in the center of the lift lifting plate 102. For example, the sensor 301 is installed in a paper feed cassette.

  The reason for installing the optical sensor 301 in this way is that when the light of the optical sensor 301 is transmitted, it can be considered that the uppermost sheet of the sheet bundle S is positioned at an appropriate height position. .

  When the rising angle detected by the angle detection unit 112 is between two angles, the angle changing unit 113 regards the top sheet of the sheet bundle S as being positioned at an appropriate height position. The lift motor 105 is not driven (YES in FIG. 2, S207).

  On the other hand, when the rising angle detected by the angle detection unit 112 is not between two angles, the angle changing unit 113 considers that the top sheet of the sheet bundle S is not positioned at an appropriate height position. The lift motor 105 is driven, and the lift bottom plate 101 is raised until the position detecting unit 111 detects again that the sheet has been raised to the proper height position (FIG. 2, S207 → S208).

  During the sheet feeding operation, the thickness of the sheet bundle S decreases due to sheet feeding, so whether the sheet is not positioned at the appropriate height position is the decrease in the thickness of the sheet bundle S or the vibration of the support frame 211. It is necessary to judge. If the angle changing unit 113 detects that the sheet is not positioned at the appropriate height position during the paper feeding operation, the position detecting unit 111 does not position the sheet at the appropriate height position. Is detected (FIG. 2, S209). As described above, the detection result of the position detection unit 111 for a certain period of time is that the shaking of the support frame 211 due to vibration or the like stops after a certain period of time. This is because it is possible to determine whether the cause of the sheet not being positioned at this position is the vibration of the support frame 211 or the paper feed.

  When the position detecting means 111 detects that the paper is not positioned at the proper height position for a certain time or more, it is determined that the paper is not positioned at the proper height position because the paper is decreased by the paper feeding operation, and the angle The changing means 113 drives the lift motor 105 to raise the lift bottom plate 101 (FIG. 2, S209 → S208).

  On the other hand, when the position detection unit 111 detects that the paper is positioned at an appropriate height position within a predetermined time, the cause of the paper not being positioned at the appropriate height position is vibration of the support frame 211 or the like. Therefore, the angle changing means 113 does not drive the lift roller 105 (FIG. 2, S209 → S210).

  As described above, the angle changing unit 113 keeps the sheet at an appropriate height position based on the detection results of the position detecting unit 111 and the angle detecting unit 112 until the paper feeding cassette is pulled out again by the user or the like. (FIG. 2, S210).

The rising angle of the angle detection means 112 can be detected by using a known motor that outputs a signal corresponding to the rotation angle of the lift motor 105.

1 is a functional block diagram of an image forming apparatus. The schematic diagram of the operation panel until a storage destination and a reading system are determined. The figure which shows that the rising angle when the paper is located at an appropriate height position differs depending on the thickness of the paper bundle. The schematic diagram of the lift raising / lowering board of this Embodiment. The conceptual diagram of the conventional paper feeder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Paper feeder 101 Lift bottom plate 102 Lift raising / lowering plate 103 Rotating shaft 104 Pickup roller 105 Lift motor 107 Storage sensor 108 Rotating shaft 110 Paper feeding cassette 111 Position detecting means 112 Angle detecting means 113 Angle changing means 210 302 Optical sensor 211 Support frame 212 Shading unit 213 housing

Claims (3)

A pickup roller to pick up the paper,
A lift elevating plate that raises the lift bottom plate on which the paper is placed by rising;
Position detecting means for detecting whether or not the sheet is positioned at an appropriate height position;
Angle detecting means for detecting the rising angle of the lift lifting plate;
A sheet feeding apparatus comprising: an angle changing unit configured to change a rising angle of the lift lifting plate based on detection results of the position detecting unit and the angle detecting unit. Measuring means for measuring a period during which the position detecting means detects that the paper is not located at the appropriate height position;
The sheet feeding device according to claim 1, wherein the angle changing unit changes the rising angle based on a detection result of the position detecting unit and the angle detecting unit and a length of a measured period. The sheet feeding device according to claim 2, wherein the angle changing unit changes the rising angle based on a detection result of the angle detecting unit when the sheet feeding operation is not being performed.

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