JP2006232430A - Separation mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separation mechanism capable of eliminating an idle turning section of a pickup roller and accurately obtaining a conveying amount and a conveying timing by a relative inexpensive constitution also using a rachet. <P>SOLUTION: The separation mechanism draws paper from a bundle of papers set in a paper piling up part, separates them in every one sheet and conveying them in a downstream and is provided with the pickup roller 7 for firstly drawing the paper. The separation mechanism realizing function freely enabling rotation in a normal direction even in the state driving is not applied to the pickup roller 7 by the rachet and is provided with mechanisms 57, 56 for removing backlash of the rachet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a separation mechanism of an original processing apparatus in an image recording processing apparatus such as a copying machine.

  In the separation mechanism, a one-way clutch is conventionally used for the pickup roller and other rollers upstream of the reading unit, and the document is pulled by the downstream conveying means, so that the trailing edge of the document comes out of the pickup roller and other rollers. Jitter due to instantaneous shock is prevented. In addition, a one-way clutch having a relatively high cost is used for the rotation (see, for example, Patent Document 1).

JP-A-6-169369

  An image forming apparatus such as a copying machine, a facsimile machine, or a printer has a paper feeding unit for calling up paper for transferring an image from a stacking unit, separating the paper one by one, and feeding the paper. Some image forming apparatuses such as copying machines and facsimile machines and image reading apparatuses such as scanners include an automatic document feeder (ADF) for conveying a document to a reading position for reading an image. A paper feeding unit is provided for recalling and feeding originals one by one from a bundle of originals set on the original stacking unit. Most of such paper feeding units include a pickup roller for calling a document first. In the following, a case will be described as a representative example in which the paper feed unit calls, separates and feeds the originals one by one from the original bundle using the ADF.

  After the pickup roller is acted and the original is called from the original bundle, the pressure and driving of the pickup roller are released so that the conveyance by the downstream conveyance means is not hindered, and the pickup roller can freely rotate in the conveyance direction. In most cases, such functions are provided. Thus, even if the document may come into contact with the pickup roller during conveyance by the downstream conveyance means, the pickup roller does not become a conveyance load. The function can be easily realized by using a one-way clutch, for example, but the cost of parts of the one-way clutch is slightly high. In addition, the one-way clutch is often integrated with the pickup roller, and when the pickup roller is replaced due to wear of the rubber part, the one-way clutch that has not reached the end of its service life will also be replaced at the same time, resulting in higher running costs. . Therefore, a ratchet may be used to obtain the function mainly for cost reduction. However, while the one-way clutch has almost no backlash, the ratchet has a certain amount of backlash. May occur. Usually, the idling section is very small, and there is no particular problem, but it is desirable that there is no idling section in terms of function even if the parts cost is low.

  The present invention has been made paying attention to the above circumstances, and the purpose thereof is to eliminate the idling section of the pick-up roller, and to carry a desired amount of transport with a relatively inexpensive configuration using a ratchet. It is another object of the present invention to provide a separation mechanism capable of obtaining the conveyance timing.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a separation mechanism that calls a sheet from a sheet bundle set in a sheet stacking unit, separates the sheets one by one, and conveys the sheets downstream in the conveying direction. In the separation mechanism that has a pickup roller for calling the paper first, and that allows the forward rotation freely even in a state where the pickup roller is not driven, the ratchet realizes the function. A mechanism for removing the backlash of the ratchet is provided.

  The invention described in claim 2 is the invention described in claim 1, wherein the backlash is removed by pressing the teeth of the ratchet on the pickup roller side and the teeth of the ratchet on the driving side against each other, and the pressing is performed. An elastic member for obtaining a force is provided as a separate part.

  The invention described in claim 3 is the invention described in claim 1, wherein the backlash is removed by pressing the teeth of the ratchet on the pickup roller side and the teeth of the ratchet on the driving side against each other, and the pressing is performed. The elastic member for obtaining the force is integrated with the drive side ratchet.

  According to the separation mechanism of the present invention, it is possible to eliminate the idling section of the pickup roller, and it is possible to obtain the intended conveyance amount and conveyance timing with a relatively inexpensive configuration using a ratchet.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The present invention relates to a sheet feeding device in general that includes a pickup roller for calling a sheet first, in a separation mechanism that calls sheets from a sheet bundle set in a sheet stacking unit, separates the sheets one by one, and conveys them downstream. However, in the following embodiments, an automatic document feeder (hereinafter referred to as ADF) used for an apparatus that reads an image to be read while conveying the document to be read to a fixed reading unit and conveying the document at a predetermined speed. Will be described. The basic configuration, operation, and action will be described with reference to a cross-sectional view of the apparatus (FIG. 1) and a control block diagram (FIGS. 2 and 3).

  A document setting unit A for setting a document bundle to be read, a separation feeding unit B for separating and feeding the documents one by one from the set document bundle, a function of performing a primary abutting and alignment of the fed documents, A resist portion C that pulls out and conveys the subsequent document, a turn portion D that turns the conveyed document and conveys the document surface toward the reading side (downward), and displays a surface image of the document from below the contact glass. A first reading conveyance unit E for reading, a second reading conveyance unit F for reading a back side image of a document after reading, a paper discharge unit G for discharging a document whose front and back have been read out of the apparatus, and a document after reading is completed Stack unit H for loading and holding, drive units 101 to 105 for driving these transport operations, and a controller unit 100 for controlling a series of operations.

  The original bundle 1 to be read is set on the original table 2 including the movable original table 3 with the original surface facing upward. Further, the width direction of the document bundle 1 is positioned in a direction perpendicular to the conveyance direction by a side guide (not shown). The document set is detected by the set filler 4 and the set sensor 5 and transmitted to the main body control unit 111 by the I / F 107. Further, the document length detection sensor 30 or 31 provided on the document table surface (a reflection type sensor or an actuator type sensor capable of detecting even one document is used) can be used to approximate the length of the document in the conveyance direction. Determined. (At least a sensor arrangement that can determine whether the document size is vertical or horizontal is required.)

  The movable document table 3 can be moved up and down in the directions a and b shown in the figure by a bottom plate raising motor 105. When the set filler 4 and the set sensor 5 detect that a document has been set, the bottom plate raising motor 105 is moved. The movable original table 3 is raised so that the uppermost surface of the original bundle contacts with the pickup roller 7 by normal rotation. The pickup roller 7 is moved by the pickup motor 101 in the c and d directions shown in the drawing by the cam mechanism, and the movable table 3 is lifted and pushed by the upper surface of the original on the movable table 3 to rise in the c direction, and the table lift detection sensor 8. The upper limit can be detected.

  When the print key is pressed from the main body operation unit 108 and a document feed signal is transmitted from the main body control unit 111 to the ADF control unit 100 via the I / F 107, the pickup roller 7 is rotated by the forward rotation of the paper feed motor 102. Is rotated to pick up several (ideally one) originals on the original table 2. The rotation direction is a direction in which the uppermost document is conveyed to the sheet feeding port. The paper feeding belt 9 is driven in the paper feeding direction by the normal rotation of the paper feeding motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feeding by the normal rotation of the 102 to separate the uppermost document from the original document below it. Thus, only the uppermost document can be fed. More specifically, the reverse roller 10 is in contact with the paper feeding belt 9 at a predetermined pressure, and when the paper is in direct contact with the paper feeding belt 9 or through a single document, the reverse roller 10 rotates. Therefore, when two or more originals enter between the paper feeding belt 9 and the reverse roller 10, the revolving force is set to be lower than the torque of the torque limiter. The roller 10 rotates in the clockwise direction, which is the original driving direction, and pushes back an excess original, thereby preventing double feeding.

  The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is further fed by the paper feeding belt 9, and the leading edge is detected by the abutting sensor 11 and further abuts against the pull-out roller 12 stopped. . After that, a predetermined amount of distance is sent from the detection of the abutting sensor 11, and as a result, the paper feed motor 102 is stopped while being pressed against the pull-out roller 12 with a predetermined amount of deflection. The drive of the paper feed belt 9 is stopped.

  At this time, when the leading end of the document detects the abutting sensor 11, the pickup roller 7 rotates the pickup motor 101 to retract the pickup roller 7 from the top surface of the document and sends the document only by the conveying force of the paper feed belt. By such an operation, the leading edge of the document enters the nip between the pair of upper and lower rollers of the pull-out roller 12, and the leading edge is aligned (skew correction). The pull-out roller 12 has the skew correction function and is a roller for conveying the skew-corrected document after separation to the intermediate roller 14 and is driven by the reverse rotation of the paper feed motor 102.

  At this time (at the time of reverse rotation of the paper feed motor 102), the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven. A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction orthogonal to the transport direction of the document transported by the pull-out roller 12. The length of the document in the conveying direction is detected from the motor pulse by reading the leading edge and the trailing edge of the document with the butting sensor 11.

  When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set higher than the transport speed at the read transport section E. The processing time for sending the document to the reading unit is shortened. When the leading edge of the document is detected by the reading entrance sensor 15, at the same time as decelerating is started in order to make the document conveyance speed the same as the reading conveyance speed before the document leading edge enters the nip between the upper and lower roller pairs of the reading inlet roller 16, The reading motor 103 is driven forward to drive the reading inlet roller 16, the reading outlet roller 23, and the CIS outlet roller 27.

  When the registration sensor 17 detects the leading edge of the document, the registration sensor 17 decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20, and transmits a registration stop signal to the main body control unit 111 via the I / F 107. Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is transported at an increased speed so as to rise to a predetermined transport speed until the leading end of the document reaches the reading position.

  At the timing when the leading edge of the document detected by the pulse count of the reading motor reaches the reading section, the gate signal indicating the effective image area in the sub-scanning direction on the first surface is sent to the main body control section 111 by the first reading section. Sent until is removed. In the case of single-sided document reading, the document that has passed through the reading conveyance unit E is conveyed to the paper discharge unit G through the second reading unit. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise.

  In addition, the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 24 reduces the discharge motor drive speed immediately before the trailing edge of the document comes out of the nip of the pair of upper and lower rollers of the discharge roller 28 to discharge the document. Control is performed so that the document discharged onto the tray 29 does not jump out. In the case of double-sided document reading, DF control is performed on the second reading unit 25 at the timing when the document leading edge reaches the second reading unit 25 by the pulse count of the reading motor after the document discharge sensor 24 detects the document leading end. A gate signal indicating an effective image area in the sub-scanning direction is transmitted from the unit 100 until the trailing edge of the original passes through the reading unit. The second reading roller 26 serves as a reference white part for acquiring shading data in the second reading unit 25 as well as suppressing the floating of the original in the second reading unit.

  As shown in FIG. 3, the second reading unit 25 includes a light source unit 200, a sensor chip 201, an A / D converter 203, an image processing unit 204, a frame memory 205, and output control. A circuit 206 and an I / F circuit 207 are provided.

Hereinafter, a case where the present invention is applied to the ADF as described above will be described.
First, FIG. 4 is a right side view of the vicinity of the pickup roller 7 of the conventional ADF separation and feeding unit B. A one-way clutch 54 is press-fitted into the pickup roller 7, and both ends are passed through a pickup roller shaft 51 supported by bearings 52. The timing pulley 51a is fixed to the pickup roller shaft 51 and rotates integrally. Drive is transmitted to the timing pulley 51 a and the pickup roller shaft 51 by the timing belt 53, and the pickup roller 7 rotates through the one-way clutch 54.

  Another conventional configuration is shown in FIG. In this case, the pickup roller shaft 51 and the timing pulley 55 are separate, and when driving is transmitted by the timing belt 53, only the timing pulley 55 rotates and the pickup roller shaft 51 does not rotate. The convex portion provided on the timing pulley 55 meshes with the concave portion of the ratchet 56, and the teeth of the ratchet 56 mesh with the teeth of the pickup roller 7, whereby driving is transmitted to the pickup roller 7. FIG. 5B is a diagram of the ratchet 56 alone. In this case, as in the case of using the one-way clutch 54 shown in FIG. 4, the pickup roller 7 can always rotate in the forward direction, that is, the pickup roller 7 does not become a load on the downstream conveying means. However, in the case of FIG. 5, there is a backlash corresponding to the pitch of the teeth of the ratchet 56, and a corresponding idling section of the pickup roller 7 is generated.

  Next, an embodiment of the present invention is shown in FIG. FIG. 6A shows an example in which an elastic body 57 such as a spring washer is added to the configuration of FIG. By the elastic body 57, the ratchet 56 is always biased weakly in the direction of the pickup roller 7, and the teeth of the ratchet 56 are always engaged. Therefore, backlash can be removed. FIG. 6B shows an example of an elastic body.

  Next, another embodiment of the present invention is shown in FIG. The ratchet 58 has an elastic portion 58 a integrated with the ratchet 58. The elastic portion 58a may be, for example, a thin plate spring bonded thereto, or a claw having elasticity formed integrally with a resin ratchet 58.

  As described above, in this embodiment, since the mechanism for removing the backlash of the ratchet of the pick-up roller is provided, the idling section of the pick-up roller can be eliminated and transported as intended with a relatively inexpensive configuration using the ratchet. Quantity and transport timing can be obtained.

  Further, in the present embodiment, since the pressurization of the mechanism for removing the backlash of the ratchet of the pickup roller is obtained by a separate elastic member, the above effect in the existing configuration can be easily obtained.

  Further, in this embodiment, the elastic member that obtains the pressurization of the mechanism for removing the backlash of the ratchet of the pickup roller is integrated with the drive side ratchet, so that the above-described effect can be obtained with the simplest and cheapest configuration. it can.

1 is a cross-sectional view of an automatic document feeder to which a separation mechanism according to an embodiment of the present invention is applied. FIG. 2 is a control block diagram of the automatic document feeder of FIG. 1. FIG. 2 is a control block diagram of the automatic document feeder of FIG. 1. FIG. 6 is a right side view of the vicinity of a pickup roller of a conventional ADF separation feeding unit. (A) is a figure which shows another conventional structure of the drive system of a pickup roller, (b) is a figure of the ratchet single-piece | unit of (a). (A) is a figure which shows an example at the time of adding an elastic body like a spring washer, for example to the structure of FIG. 5, (b) is a figure of an elastic body. It is a figure which shows another Example of this invention.

Explanation of symbols

7 Pickup roller 56 Ratchet 57 Elastic body

Claims (3)

A separation mechanism that recalls sheets one by one from a bundle of sheets set in a sheet stacking unit and separates the sheets one by one and conveys them downstream in the conveyance direction. In the separation mechanism that realizes the function that allows forward rotation freely even in a state where the drive is not applied, by the ratchet,
A separation mechanism comprising a mechanism for removing backlash of a ratchet.   2. The elastic member for removing the backlash by pressing the teeth of the ratchet on the pickup roller side and the teeth of the ratchet on the driving side against each other and obtaining the pressing force is provided as a separate part. Separation mechanism. The backlash is removed by pressing the teeth of the ratchet on the pickup roller side and the teeth of the drive side ratchet against each other, and the elastic member for obtaining the pressing force is integrated with the driving side ratchet. The separation mechanism according to claim 1.

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