JP2005231773A - Paper feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder that improves paper feeding stability, by removing an effect of mechanical vibration included in a detection signal from a top face detecting means for detecting paper top face and by controlling the position of the paper top face for detecting the position of the paper top face. <P>SOLUTION: The paper feeder is disposed in an image forming device and feeds paper one by one from loaded paper to a paper conveying means. The paper feeder has the top face detecting means for detecting the top face of the loaded paper and a control means for recognizing the top face detection information when the output level of the top face detecting means changes from L to H or from H to L and then the output level does not change in a preset time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet feeding device that separates sheets one by one from stacked sheets and sends them to a sheet conveying unit in an image forming apparatus.

  In recent years, in the development of image forming apparatuses such as copiers and printers, it has become important to achieve high speed and to minimize the installation area. However, in general, when the image forming apparatus is reduced in size, there is a problem that the operation of each unit housed inside affects the operation of other units. In particular, mutual influences related to heat, vibration, and electromagnetic induction are large.

  With regard to vibration, specific cycle or intermittent vibration is generated by the operation of mechanical movement elements such as motors and other driving means, gears and other power transmission means, moving optical systems, rollers, belts, fans and the like. .

  Various detection means are attached inside the image forming apparatus, and some of these are detection means that electrically take in mechanical displacement. In such a detection means, since a movable member (actuator) that moves in response to a mechanical displacement or force is affected by vibration, it is necessary to devise measures to prevent this influence.

  In an image forming apparatus such as a copying machine or a printer, a toner image formed on a photoconductor is transferred onto a sheet as a transfer material by a transfer unit. The sheets are taken out one by one from a plurality of sheets stacked and stored in a sheet cassette or a sheet tray by a sheet feeding device, conveyed by a sheet conveying unit, and provided in the vicinity of the photosensitive member. Then, the tip is abutted by the registration roller and is sent out toward the photoconductor in accordance with the position of the toner image formed on the photoconductor.

  The paper feeding device is provided with an upper surface detecting means for detecting the height position of the upper surface on the upper surface of the stacked paper, and the upper surface position is set when the stacked paper is fed one by one to the paper transport path. The upper surface detection signal used for the control for always maintaining a certain range is obtained. As a result of considering the characteristics of various types of paper used, the upper surface detecting means is provided with a pressing member that applies a slight pressure to the upper surface of the paper as an actuator and optically detects the displacement of the pressing member. There are many cases.

  If the pressure of the pressing member is too strong, the upper surface of the stacked paper will be deformed by the pressing and cause a jam at the time of feeding, and if it is too weak, it will easily vibrate due to the mechanical operation of various means in the image forming apparatus. Thus, an erroneous signal is generated in the optical sensor that optically detects the displacement of the pressing member.

In order to cope with such inconvenience, there is also a proposal that the detection signal is captured only at a specific time based on the operation of a predetermined means and is not captured at other times (for example, , See Patent Document 1). In addition, a method of prohibiting the capture of a detection signal during the operation of a specific unit that greatly affects the upper surface detection unit, for example, during the operation of a sheet feeding device or a sheet transport unit is widely adopted. However, the detection restriction of the detection signal as described above may miss the detection timing. If the detection timing is delayed, paper feeding is performed at an inappropriate position on the upper surface of the paper, causing jamming, and in some cases, the upper surface of the paper may rise too much and come into contact with an upper member.
Japanese Patent Application Laid-Open No. 9-77312 (page 2, right column, page 3, left column)

  The present invention has been made in view of the above situation, and an object of the present invention is to eliminate the influence of mechanical vibration included in the detection signal from the upper surface detecting means for detecting the upper surface of the paper, and to always maintain the upper surface of the paper. An object of the present invention is to provide a sheet feeding device having high sheet feeding stability by performing sheet upper surface position control for detecting the position.

The said subject is achieved by achieving the following items.
(1) A paper feeding device that is provided in the image forming apparatus and feeds paper one by one from the stacked paper to the paper transporting means,
Upper surface detection means for detecting the upper surface of the stacked paper;
Control means for recognizing the upper surface detection information when the output level does not change within a preset time after the output level of the upper surface detection means has changed from L to H or from H to L. A paper feeding device.
(2) A paper feeding device that is provided in the image forming apparatus and feeds paper one by one from the stacked paper to the paper transporting means,
Upper surface detection means for detecting the upper surface of the stacked paper;
The output level of the upper surface detecting means is captured at a set cycle, and when the captured output level changes from L to H or from H to L, the captured output level changes within a preset time. And a control means for recognizing the upper surface detection information when it is not.
(3) The sheet feeding device according to (1) or (2), wherein a different set time is set in the control means in correspondence with the operation timing of the image forming apparatus or the sheet feeding device. .
(4) The upper surface detecting means is
A member whose one end rotates about an axis and whose other end presses the upper surface of the stacked paper;
The sheet feeding device according to any one of (1) to (3), including an optical sensor that detects a displacement of the member.

  According to the first aspect of the invention, since the upper surface detection signal from the upper surface detection means is recognized as valid upper surface detection information only when it has not changed for the set set time or more, mechanical vibration that occurs in a short time is recognized. The influence of is removed.

  According to the invention of claim 2, since the upper surface detection level of the upper surface detection means is recognized as valid upper surface detection information only when it has not been changed by a plurality of samplings executed within the set set time, The effects of mechanical vibrations that occur in a short time are eliminated.

  According to the invention of claim 3, the set time of claim 1 or claim 2 can be set in correspondence with the characteristic of vibration induced by the operation of each means in the image forming apparatus.

  According to the fourth aspect, the upper surface detecting means used in the paper feeding device according to the first to third aspects can be configured to be adapted to the upper surface detection.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an image forming apparatus G.

  The image forming apparatus G is a digital copying machine, and includes an automatic document feeder 1, a reading unit 2, a writing unit 3, an image forming unit 4, a fixing unit 5, a reverse discharge unit 6, a refeed unit 7, The paper transport unit 8, the paper feeding device 9, the control unit C, and the like are included.

  The automatic document feeder 1 sends the documents D placed on the document table 10 to the document transport path 11 one by one and discharges them to the document discharge table 12. The image surface of the document D being conveyed is read by the reading unit 2 at the document reading position 13. When scanning images on both sides of the document D, the document D that has been scanned on the first surface is reversed by the reversing means 14 and sent again to the document transport path 11 to read the second surface, and the document is discharged. The paper is discharged onto the paper board 12.

  The reading unit 2 includes a light source 21, a first mirror unit 22, a second mirror unit 23, an imaging lens 24, a CCD 25, and the like. The original image information, which is optical information, is converted into electrical information. The converted document image information is subjected to processing such as A / D conversion, shading correction, and compression, and is stored in the memory M of the control means C.

  The writing unit 3 is a scanning optical system composed of a laser light source, a cylindrical lens, an Fθ lens, a mirror, a polygon, and the like, and forms an image with a laser beam that changes in accordance with image information read from the memory M. The surface of the photoconductor 41 of the means 4 is scanned to form a latent image on the surface of the photoconductor 41.

  The image forming unit 4 develops the latent image formed on the surface of the photoconductor 41 with the developing unit 42 and visualizes it as a toner image. The toner image is transferred to the paper P sent out by the registration roller 81 by the transfer means 43. After the toner image has been transferred, the surface of the photosensitive member is subjected to the removal of residual toner by the cleaning unit 44 and is charged by the charging unit 45 to be used for the next latent image formation.

  The fixing unit 5 fixes the toner image on the paper P by heating and pressurizing the paper P carrying the toner image by the heat roller 51 and the pressure roller 52 that are arranged to face each other.

  The paper P on which image fixing has been completed is discharged onto a paper discharge tray 56 by a paper discharge roller 55.

  When the paper P is reversed and discharged, the paper P is guided downward by the paper discharge guide 57, the rear end of the paper P is sandwiched between the reverse rollers 61 of the reversing means, and the paper P is reversed to the discharge rollers 55. Send it out.

  When image formation is performed on both sides of the paper P, the paper P is sent to the paper refeeding means 7 by the paper discharge guide 57 and a plurality of rollers, and the paper P is reversed by the reversing roller 71 of the paper refeeding means 7. The paper is again sent to the paper conveying means 8.

  The sheet conveying means 8 conveys the sheet P sent from the sheet feeding device 9 through a sheet conveying path composed of a plurality of rollers and a guide member, and abuts the leading end of the sheet P against the registration roller 81. Then, the toner image is sent out toward the photosensitive member 41 to receive the toner image.

  The sheet feeding device 9 includes a first sheet feeding unit 91 having a small capacity tray, a second sheet feeding unit 92 having a large capacity tray, and a third sheet feeding unit 93. Each of the paper feeding units has feed rollers 916, 926, and 936 that feed the paper P placed on each tray to the paper transport unit 8 one by one. The second paper feed unit 92 and the third paper feed unit 93 are provided with upper surface detection means 920 and 930 for detecting the upper surface position of the stacked paper, and based on the upper surface detection signal from the detection means. The control means C moves the bottom of the tray on which the paper P is stacked up and down.

  FIG. 2 is a block diagram showing the control relationship of the image forming apparatus G in the present embodiment.

  The control means C is a computer system including a CPU, an arithmetic unit, a memory M, an input / output I / F, communication means, a drive circuit, and the like. Control of each means is performed by executing a program stored in the memory M in advance. In the present invention, the control means of the paper feeder 9 is included in the control means C. Further, in this drawing, the description of blocks unnecessary for the description of the present embodiment is omitted.

  FIG. 3 is a diagram schematically showing the vicinity of the upper surface detecting means 930 of the third paper feeding means 93.

  The upper surface detection means 930 includes a rotation shaft 931, an actuator 932 that can rotate around the rotation shaft 931, and a transmission type optical sensor 933 that optically detects a hole 934 formed in the actuator 932. Yes. As shown in the drawing, the actuator 932 is in contact with the upper surface of the stacked paper P and presses the paper P lightly.

  Note that the actuator 932 may be provided with a roller in a portion in contact with the upper surface of the paper P. Further, the method of optically detecting the position of the actuator 932 is not limited to the above example, and an appropriate method can be adopted.

  The sheets P stacked on the bottom plate 935 of the tray of the third sheet feeding means 93 and maintained at a certain upper surface position are stopped one by one by the rotation of the feed roller 936 whose drive is controlled by the control means C. It is sent out to the sheet conveying means 8 in the direction of arrow a. When transport of the paper P is started by the transport rollers 82 and 83 of the paper transport unit 8, the feed roller 936 moves upward so as not to hinder the transport of the paper P by the paper transport unit 8.

  When the paper P placed on the top is sequentially sent out, the position where the actuator 932 is in contact with the paper P is gradually lowered, and the hole of the actuator 932 is detected by the optical sensor 933. Upon receiving the detection signal from the optical sensor 933, the control means C drives a tray driving means (not shown) that moves the tray bottom plate 935 up and down to raise the tray, and the hole is detected again by the optical sensor 933. When it runs out, it stops raising the tray.

  The output of the optical sensor 933 is a binary output of a high level (H) and a low level (L). In this description, H is output and detected when the upper surface is being detected. It is assumed that L is output when there is no state, but it is also possible to configure the upper surface detection means 930 with the reverse logic.

  However, in the upper surface detection means 930 as described above, when the actuator 932 vibrates, the output level of the optical sensor 933 may show fluctuations due to the vibration of the actuator 932 as shown in FIG. . This vibration is caused by the operation of various means provided in the image forming apparatus G, for example, a drive means such as a motor, a power transmission means such as a gear, a mechanical element such as a moving optical system, a roller, a belt, and a fan. Caused by the operation of In particular, the upper surface detection unit 930 is affected by the operation of the adjacent paper transport unit 8 and the accompanying vibration of the paper P being fed.

  The simplest method for removing this influence is to prevent the control means C from accepting the signal from the optical sensor 933 while the paper P is being transported by the paper transporting means 8. Since the control for always maintaining the upper surface at the optimum position is interrupted, the upper surface is lowered too much, or the upper surface becomes too higher than the predetermined position due to a delay in stopping the raising of the bottom plate 935 of the tray. May cause inconvenience.

  The present invention measures the level fluctuation period of the optical sensor 933 due to the vibration of the actuator 932, provides a set time longer than the obtained period, and within the set time when the level of the optical sensor 933 fluctuates. Again, when the level of the optical sensor 933 fluctuates, it is determined that the level fluctuates due to the influence of vibration. When there is no level fluctuation of the optical sensor 933 within the set time, it is determined that the level fluctuates due to fluctuation of the upper surface position. Is.

  For example, in the image forming apparatus G used in the experiment, the gear used to drive the roller used in the paper transport unit 8 is a source of vibration of 50 Hz, and the gear rotates. The actuator 932 of the upper surface detection means 930 was vibrated when the operation was in progress. The level fluctuation from the optical sensor 933 due to this vibration is as shown in FIG. In this case, a level fluctuation with a period t1 = 10 ms is output by vibration of 50 Hz. Therefore, if the set time T1 is set such that T1 = 15 ms, it is determined that it is not the upper surface detection information when the level change occurs within 15 ms after the first level change (t0) occurs. Further, as shown in FIG. 4B, when there is no level change within the set time T1, it is determined that the upper surface detection information.

  By obtaining the detection information in this way, it is possible to always detect the upper surface, and more accurate upper surface position control is possible.

  FIG. 5 is a flowchart showing the flow of the upper surface detection signal determination means which is a program for performing the above-described control.

  When the output level of the optical sensor 933 fluctuates from H to L or from L to H, the control means C detects that the level has fluctuated from the rise or fall of the level signal (step S1). When level fluctuation is detected, T1 which is a preset time is set in a soft timer (T) created as a program (step S2). When the setting is completed, the timer starts measuring time (step S3). If the level fluctuation signal from the optical sensor 933 is detected while the timer (T) is measuring time (step S4: Y), the level fluctuation detected in step S1 is detected by the upper surface detection. If the level fluctuation signal from the optical sensor 933 is not detected while the timer (T) reaches the set time T1 without being recognized as information (step S5: N, step S6: Y), step The level fluctuation detected in S1 is recognized as the upper surface detection information.

  In the above example, the 933 level fluctuation of the optical sensor is taken as an interrupt signal to the control means C, and the upper surface detection signal determination means which is a program for obtaining the upper surface detection information is activated. The timer interrupt function of the optical sensor 933 may periodically fetch the level of the optical sensor 933, and the upper surface detection information determination means may be activated when the fetched level varies.

  In the above-described example, the influence of the vibration of the actuator 932 due to the conveyance of the paper P has been described. However, other influences, for example, the reciprocating motion of the optical system and the one that affects the vibration of the actuator 932 are specified. May be provided with a specific set time effective only at a specific timing related to the operation based on the result of vibration measurement. In this case, a step for confirming the operation status of each unit of the image forming apparatus G or the operation status of the sheet feeding device is provided between steps S1 and S2 in the flowchart of FIG. A corresponding set time may be selected and set in the timer (T) from a plurality of set times provided in advance as a table according to the operation status.

1 is a schematic diagram of an image forming apparatus. 2 is a block diagram illustrating a control relationship of the image forming apparatus. FIG. It is a figure which shows the vicinity of an upper surface detection means. It is a figure which shows the level fluctuation | variation of an optical sensor, and setting time. It is a flowchart which shows the flow of a process of an upper surface detection signal determination means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Reading means 3 Writing means 4 Image forming means 5 Fixing means 6 Reverse discharge means 7 Refeed means 8 Paper transport means 9 Paper feed device 93 Third paper feed means 930 Upper surface detection means 931 Rotating shaft 932 Actuator 933 Optical sensor 934 Hole 935 Bottom plate 936 Feeding roller C Control means G Image forming apparatus D Document P Paper T1 Setting time

Claims (4)

A paper feeding device that is provided in an image forming apparatus and feeds paper one by one from a stacked paper to a paper transport unit,
Upper surface detecting means for detecting the upper surface of the stacked paper;
Control means for recognizing the upper surface detection information when the output level does not change within a preset time after the output level of the upper surface detection means has changed from L to H or from H to L. A paper feeding device. A paper feeding device that is provided in an image forming apparatus and feeds paper one by one from a stacked paper to a paper transport unit,
Upper surface detecting means for detecting the upper surface of the stacked paper;
The output level of the upper surface detection means is captured at a set cycle, and when the captured output level changes from L to H or from H to L, the captured output level changes within a preset set time. And a control means for recognizing the upper surface detection information when it is not. The sheet feeding device according to claim 1, wherein a different set time is set in the control unit in accordance with an operation timing of the image forming apparatus or the sheet feeding device. The upper surface detection means is
A member whose one end rotates about an axis and whose other end presses the upper surface of the stacked paper;
The sheet feeding device according to claim 1, further comprising an optical sensor that detects a displacement of the member.

Images