JP4657874B2 - Paper feeder - Google Patents

Description

  The present invention relates to a sheet feeding device, and more particularly, to a sheet feeding device that feeds a document to a document reading unit in an image forming apparatus such as a copying machine.

  FIG. 5 is a conceptual diagram of a conventional paper feeder, and is described in Japanese Patent Application Laid-Open No. 2004-107060 (Patent Document 1). In FIG. 5, the paper 100 placed on the paper placement table 31 is picked by the pick roller 32 in a state where an appropriate pressing force is applied by the pickup arm 33. At this time, the sheets 100 are separated one by one from the lower side by the pick roller 32 and the separation pad 34. The picked paper 100 is further transported by the pick roller 32 to feed rollers 35 and 36 provided on the downstream side of the paper feed path, transported to the reading position R by the feed rollers 35 and 36, and discharged rollers 37 and 38. It is discharged by.

In the example shown in FIG. 5, the pick roller 32 is in contact with the lower surface of the paper 100, but the vertical positions of the pick roller 32 and the separation pad 34 are reversed so that the pick roller 32 contacts the upper surface of the paper 100. Some are in contact.
Japanese Patent Laying-Open No. 2004-107060 (paragraph numbers 0011 and 0012, FIG. 2)

  The separation pad 34 disclosed in Patent Document 1 is provided to prevent double feeding. However, when the final paper is fed, the separation pad 34 is loaded with this double feed prevention pad, which may cause a paper feed failure depending on the type of paper. For this reason, a contrivance is required for the setting so that the relationship between the sheet feeding force and the frictional force between the separation pad 34 matches.

  Although not shown, a sensor for detecting whether or not there is paper is provided, and the paper is picked by the pick roller 32 until the sensor detects that there is no paper. The response is slowed down for the purpose. For this reason, even if the paper runs out, the pick roller 32 and the separation pad 34 are rubbed.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a paper feeding device that makes it easy to feed the final paper, has a setting margin, and can achieve a long life.

The present invention is a paper feeding device that feeds paper one by one from a paper storage means for storing a plurality of papers, and a roller for feeding the paper stored in the paper storage means, A contact plate for pressing the paper of the paper storage means against the roller, and a sheet of paper stored in the paper storage means is left , a sensor for detecting prior to the paper feed of paper by the roller, when the paper feed, is contacted with the roller abutment plate, depending on the paper is detected to have become one remaining by the sensor, the And a control means for releasing the contact between the contact plate and the roller after the paper is fed .

  Specifically, the sensor is an ultrasonic sensor including a transmission unit and a reception unit that are arranged to face each other with paper interposed therebetween.

Preferably, according to the paper is detected to have become one remaining by sensor, by rotating the abutment plate under the control of the control means includes a drive means to separate from the roller.

  Preferably, a pad is disposed on the contact plate so as to face the roller.

  Further, it includes a paper detection means for detecting whether or not there is paper in the paper storage means, and the control means detects that the paper detection means is present, and the sensor detects that the remaining paper is one sheet. In response to this, the contact between the roller and the contact plate is released.

  According to the present invention, when the paper is fed, the roller and the contact plate are brought into contact with each other, and the contact between the contact plate and the roller is detected when the sensor detects that the remaining sheet is one sheet. Is released so that the final paper can be easily fed, the likelihood of setting is increased, and a longer life can be achieved.

  FIG. 1 is a schematic sectional view of a sheet feeding device according to an embodiment of the present invention. In FIG. 1, the paper feeding device 1 is provided with a paper placing table 2 as a paper storage unit, and the papers placed on the paper placing table 2 are sequentially taken into the inside. An ultrasonic sensor transmission unit 3 and an ultrasonic sensor reception unit 4 are provided to face each other at the front end portion of the paper mounting table 2. The ultrasonic sensor transmission unit 3 and the ultrasonic sensor reception unit 4 detect whether or not there is one remaining sheet placed on the sheet placing table 2.

  Further, a forward feed roller 5 and a lift plate 6 as a contact plate are provided at the tip. The lift plate 6 feeds the paper by bringing it into contact with the forward feed roller 5 so that the force is transmitted by pushing up the leading end of the paper placed on the paper placement table 2 during paper feeding. It is driven by the plunger. When the paper on the paper placing table 2 runs out, the lift plate 6 is lowered to make it easier to set paper again. A pad 7 is affixed to the lift plate 6, and when two sheets of paper are stacked and fed as the final sheet, only the upper sheet is fed by the forward feed roller 5, and the lower sheet is fed. It is easy to slip on the pad 7.

  In the vicinity of the lift plate 6, a set switch 8 is provided as paper detection means. The set switch 8 detects whether or not paper is set. The set switch 8 is constituted by a reflection type photo sensor, a photo interrupter, or the like. A paper feed roller 9 and a separation roller 10 are provided on the downstream side of the paper feed path of the forward feed roller 5. The forward feeding roller 5 and the paper feeding roller 9 rotate in the same direction as indicated by the arrows in FIG. 1, and even if a plurality of sheets are fed from the forward feeding roller 5, the paper feeding roller 9 And the separation roller 10, and the paper is fed one by one. When two sheets are stacked as the final sheet from the advance roller 5 and are fed to the sheet supply roller 9 and the separation roller 10, only the upper sheet is in contact with the advance roller 5 and the lower sheet Slips on the pad 7, so only the upper paper is fed.

  FIG. 2 is a block diagram of the sheet feeding device shown in FIG. 1, and FIG. 3 is a diagram showing a waveform diagram in which the ultrasonic sensor receiving unit receives ultrasonic waves transmitted from the ultrasonic sensor transmitting unit.

  In FIG. 2, a set switch 8, an ultrasonic sensor transmission unit 3, an ultrasonic sensor reception unit 4, a motor 11, and a plunger 12 are connected to the control unit 21. The motor 11 rotates the forward feed roller 5, the paper feed roller 9, and the separation roller 10 shown in FIG. 1, and the plunger 12 raises and lowers the lift plate 6 shown in FIG.

  When one sheet of paper exists between the ultrasonic sensor transmitter 3 and the ultrasonic sensor receiver 4 as shown in FIG. 3 (A), the ultrasonic sensor receiver as shown in FIG. 3 (B). In 4, an ultrasonic wave from the ultrasonic sensor transmitter 3 is received and a received waveform appears. However, when two or more sheets of paper overlap each other as shown in FIG. 3C, no received waveform appears in the output of the ultrasonic sensor receiver 4 as shown in FIG. Further, when the thickness of the paper is equal to or greater than a predetermined thickness as shown in FIG. 3E, a slight output waveform appears in the output of the ultrasonic sensor receiver 4 as shown in FIG. Therefore, if the output waveform of the ultrasonic sensor receiver 4 is a waveform as shown in FIG. 3B, it can be determined that the paper on the paper placing table 2 is the final paper.

  FIG. 4 is a flowchart for explaining the operation of the sheet feeding device according to the embodiment of the present invention.

  When a plurality of sheets of paper are placed on the paper placement table 2, the set switch 8 is depressed by the weight of the paper and is turned on. In addition, since a plurality of sheets of paper are placed on the paper placement table 2, no received waveform appears in the ultrasonic sensor receiver 4 as shown in FIG. Further, the lift plate 6 is pushed up by the plunger 12 so as to contact the forward feed roller 5, and the pad 7 is in contact with the forward feed roller 5.

  The control unit 21 determines whether or not the set switch 8 is ON in a step (abbreviated as SP in the drawing) SP1 shown in FIG. If the set switch 8 is ON, it is determined in step SP2 whether there is an output from the ultrasonic sensor receiver 4. If there is no output from the ultrasonic sensor receiver 4, it is determined that there are a plurality of sheets on the sheet placing table 2, and a normal sheet feeding process is performed in step SP4. That is, the pad 7 is brought into contact with the forward feeding roller 5 and is fed one by one from the top among a plurality of sheets. Steps SP1, SP2 and SP4 are repeated, and the paper on the paper mounting table 2 is fed one by one by the forward feeding roller 5, and the paper is separated by the paper feeding roller 9 and the separation roller 10, and only one sheet is fed. To feed.

  In step SP1, the set switch 8 is turned on, and when the ultrasonic sensor receiver 4 outputs a received waveform as shown in FIG. 3B in step SP2, one sheet that is the final sheet is detected. In step SP3, the plunger 12 is driven and the lift plate 6 is pulled down. Thereby, the pad 7 in contact with the forward feed roller 5 is separated from the forward feed roller 5. Since the lift plate 6 is separated from the forward feed roller 5, the feeding of the one sheet as the final sheet is not hindered by the pad 7, so that jamming can be prevented. Further, since the pad 7 is separated from the forward feed roller 5, the wear of the two due to contact with the forward feed roller 5 rotating the pad 7 can be reduced, so that the lifetime can be extended.

  When it is determined in step SP1 that the set switch 8 is OFF, in step SP5, the motor 11 is stopped to stop the rotation of the forward feed roller 5, and the paper feed end process is performed.

  In the above-described embodiment, the ultrasonic sensor detects that there is only one sheet remaining. However, the present invention is not limited to this, and other sensors that detect the amount of transmitted light may be used. Good.

  In the above-described embodiment, the lift plate 6 is brought into contact with or separated from the forward feed roller 5. However, the lift plate 6 is fixed and the forward feed roller 5 is moved to the lift plate. You may comprise so that 6 may contact | abut or leave | separate.

  Further, in the embodiment shown in FIG. 1, the paper feed mechanism in which the forward feed roller 5 is in contact with the upper surface of the paper has been described. However, as shown in FIG. 5, a paper feed mechanism in contact with the lower surface of the paper may be used. Good.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a schematic sectional drawing of the paper feeder of one Embodiment of this invention. FIG. 2 is a block diagram of the paper feeding device shown in FIG. 1. It is a figure which shows the transmission part of an ultrasonic sensor, a receiving part, and a waveform diagram. It is a flowchart for demonstrating operation | movement of the paper feeder of one Embodiment of this invention. It is a conceptual diagram of the conventional paper feeder.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Paper feeder, 2 Paper mounting stand, 3 Ultrasonic sensor transmission part, 4 Ultrasonic sensor receiving part, 5 Forward feed roller, 6 Lift board, 7 Pad, 8 Sensor switch, 9 Paper feed roller, 10 Separation roller, 11 Motor, 12 plunger, 21 control unit.

Claims (5)

A paper feeding device that feeds paper one by one from a paper storage means for storing a plurality of papers,
A roller for feeding the paper stored in the paper storage means;
A contact plate that is rotatably provided so as to be in contact with or separated from the roller, and that presses the paper of the paper storage means against the roller;
A sensor for detecting before the paper stored in the paper storage means is one sheet before the paper is fed by the roller ;
When the paper is fed, the roller and the contact plate are brought into contact with each other, and the contact plate is fed after feeding the paper in response to the sensor detecting that the remaining paper is one sheet. and control means for releasing the contact between the roller and the sheet feeder.   The sheet feeding device according to claim 1, wherein the sensor is an ultrasonic sensor including a transmission unit and a reception unit that are arranged to face each other with the paper interposed therebetween. Depending on the paper is detected to have become one remaining by the previous SL sensor, by rotating the abutment plate under the control of said control means includes a drive means away from the roller, according to claim 1 Or the sheet feeding device described in 2.   The sheet feeding device according to claim 1, wherein a pad is disposed on the contact plate at a position facing the roller. Including paper detection means for detecting whether or not there is paper in the paper storage means,
The control means detects the presence of paper by the paper detection means, and the contact between the roller and the contact plate is detected when the sensor detects that the remaining paper is one sheet. The sheet feeding device according to claim 1, wherein the sheet feeding device is released.

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